Title of Invention	VALVE DEVICE HAVING A SOFT START FUNCTION
Abstract	Abstract of the Disclosure A valve means (6) has a softstart valve (21). The softstart valve (21) possesses a principal valve, which is able to be switched over between a home position, a softstart position and a working position. For switching over into the softstart position and into the working position there is a pilot valve, which supplies a fluid pilot signal. This signal is directly supplied to the principal valve (24) and, for switching over into the working position additionally indirectly by way of a switch over valve (26), whose operational state is governed by the secondary pressure obtaining in a secondary duct (2). Figure 2.

Title of Invention

VALVE DEVICE HAVING A SOFT START FUNCTION

Abstract

Abstract of the Disclosure A valve means (6) has a softstart valve (21). The softstart valve (21) possesses a principal valve, which is able to be switched over between a home position, a softstart position and a working position. For switching over into the softstart position and into the working position there is a pilot valve, which supplies a fluid pilot signal. This signal is directly supplied to the principal valve (24) and, for switching over into the working position additionally indirectly by way of a switch over valve (26), whose operational state is governed by the secondary pressure obtaining in a secondary duct (2). Figure 2.

Full Text	-- VALVE DEVICE HAVING A SOFT START FUNCTION -- The invention relates to a valve means with a softstart function that is to say a function rendering possible a gradual and not abrupt build up of pressure on the secondary side. The German patent publication DE 91 05 458 Ul discloses such a valve means, which has a softstart valve made up of several individual valves. A shut off valve designed as a valve with two positions is placed on the connection between a primary duct connected with a pressure source and a secondary duct connected with the loads to be supplied and may close the connection (home position) or open it (working position). Switching over into the working position is caused within a certain period of time after operation of a pilot valve which is placed on a softstart duct bypassing the main valve which furthermore has a choke means. By way of a branch from the softstart duct moreover the secondary pressure obtaining in the secondary duct is switched to the main valve as a control pressure effective toward the working position. As from the activation of the pilot valve the secondary duct is supplied via the softstart duct in a choked manner with pressure medium from the primary duct. Accordingly in the secondary duct there is a gradual increase in pressure. When the secondary pressure has reached a predetermined level the main valve switches over into the working position with the result that then the main valve is supplied via the larger flow cross section of the main valve until the secondary pressure finally reaches the level of the primary pressure. In the known valve means it is possible for a brief drop in pressure, due to pressure fluctuations, in the secondary duct to cause the main valve to switch over into the home position so that the system is accordingly back in the softstart mode for some time. This may entail substantial impairments in function, because the connected loads cannot be supplied with the necessary amount of fluid for a short time. Furthermore a relatively large size of pilot valve is required in order to ensure the greater flow rate which may in some circumstances be required even in the softstart phase, something which all in all means large dimensions of the softstart valve. A softstart device disclosed in the German patent publication DE 20 2004 015 468 Ul is similarly designed, A shut-off valve is able to be switched over by the gradually increasing secondary pressure from a shut home position into an open working position. The build up of pressure on the secondary side is predetermined by a choke means placed on a softstart duct bypassing the shut off valve. The device is started by the simultaneous operation of two further valve means placed on the duct, by which furthermore venting of the softstart device is possible. The US patent 5,669,422 discloses a softstart valve with a valve able to be switched over between three positions. The switching over from the home position into a softstart position is caused by a pilot valve. Switching over from the softstart position into a working position is entailed by the gradually increasing secondary pressure which as from the softstart position continuously acts on the principal valve. One object of the present invention is to provide a valve means, having a reliably operating but nevertheless compactly dimensioned softstart means. This object is achieved with a valve means having a softstart valve comprising the following features: - a principal valve able to be switched over between a home position, a softstart position and a working position, and which in the home position separates a secondary duct from a primary duct conducting pressure medium subject to a primary pressure, which in the softstart position joins the secondary duct, via a softstart duct containing choke means, with the primary-duct and which in the working position by bypassing the choke means opens a connection between the secondary duct and the primary duct - a pilot valve provided for influencing the switching position of the principal valve, on whose operation a fluid pilot signal is generated acting on a first actuating face of the principal valve in order to switch over the principal valve out of the home position and into the softstart position, - and a switch over valve able to be operated by the secondary pressure obtaining in the secondary duct, which valve at a predetermined level of the secondary pressure switches over the fluid pilot signal, produced by the pilot valve to a second actuating face of the principal valve in order to switch over the principal valve out of the softstart position into the working position. The principal valve of the softstart valve is accordingly designed in the form of an at least three position valve, which in addition to the home position and the working position may also assume a softstart position responsible for the softstart phase. While in the prior art the softstart fluid flow is conducted through the pilot valve bypassing the principal valve, in accordance with the invention it flows through the principal valve without recjuiring any direct control by the pilot valve. The preferably electrically operated pilot valve is responsible for the diverse switching positions of the principal valve in conjunction with the additional switching over valve. The fluid signal valve produced by the pilot valve switches the principal valve into the softstart position. When after a certain period of time the secondary pressure has reached the switch over threshold, it then causes such an actuation of the switch over valve that the fluid pilot signal is applied to a further actuating face so that the principal valve is switched over from the soffcstart position into the working position ensuring a higher flow rate. The switch over valve is preferably fluid-operated, the secondary pressure being applied to it directly as a control pressure. The switch over valve may in this case be for instance operate as a sort of pressure bridge. As an alternative a merely indirect activation of the switch over valve by the secondary pressure would be possible by employing an electrically activated switch over valve, whose switch over signal is generated with the aid of a pressure sensor or pressure switch responsive to the secondary pressure. The latter feature renders possible a particularly simple variation of the switch over threshold. Since the secondary pressure itself does not act directly as an actuating pressure on the principal valve, there is a pilot signal leading to uncoupling from the pilot signal supplying the switch over force for the principal valve. Accordingly a circuit arrangement is possible in which pressure fluctuations occurring in the working position in the primary duct and/or of the secondary duct do not affect the switching position of the principal valve. This renders possible trouble-free operation until the pilot valve is turned off. Further advantageous developments of the invention are defined in the dependent claims. It is convenient to so design the principal valve that in its home position it entails the pressure relief in the secondary duct, that is to say in a pneumatic application a venting of the secondary duct. The pressure relief by way of the principal valve makes unnecessary the use of separate venting valve or venting through the pilot valve. The choke means responsible for the speed of a pressure build-up in the secondary duct are preferably adjustable. For instance, the choke means can comprise a choke screw screwed into the Valve housing to an adjustable degree. The principal valve, the pilot valve and the switch over valve are preferably combined together as a subassembly constituting the softstart valve. This provides for a simplification of handling during installation and removal. The pilot valve will more particularly be a solenoid valve. Other electrically activated valves are nevertheless able to be employed, as for example piezoelectric valves or electrostatic valves. It is convenient for the two actuating faces of the principal valve to face in the same direction. The switch over from the home position into the softstart position and from the softstart position into the working position occurs in this case with the same direction of switch over movement; such movement preferably being linear. Preferably the principal valve possesses a main valve member able to be positioned in a corresponding number of switching positions to set its switching positions, more particularly in the form of a valve spool. For switching over the first and the second actuating face cooperate together with the main valve member in a driving manner. While the second actuating face responsible for switching over into the working position is preferably arranged stationarily on the main valve member, the first actuating face, responsible for the switching over into the softstart position, is preferably provided on an actuating element separate from the main valve member. This actuating element is so uncoupled from the main valve member that the latter may be switched over without entraining the actuating element into the working position. Therefore while during switching over from the home position into the softstart position preferably both actuating faces are shifted jointly, during switching over into the working position the first actuating element lags behind and the second actuating face moves away from it. The reason for the above mentioned timing is conveniently the presence of an abutment face arranged in the path of motion of the actuating element, which defines the softstart position. The actuating element is preferably designed in the form of an actuating piston. Alternatively however a design in the form of an actuating diaphragm would also be possible. Preferably the principal valve member is biased by a preferably mechanical return spring means into the home position. Following switching over into the softstart position the return spring means is compressed to a certain degree, the degree of compression being further increased until the working position is reached. After deactivation of the pilot valve the return spring means ensures a return in the principal valve member into the home position. The action of the pilot pressure on the first actuating face preferably takes place directly via a pilot control duct under the control of the pilot valve. The action on the second actuating face preferably best takes place via a switch over duct branching off from the pilot control duct, the switch over valve being placed on the switching over duct and being able to shut or open the switching over duct. The switch over valve preferably comprises a moving switch over valve member. The same is controlled and operated on the basis of the secondary pressure. Direct actuation, if required, by the secondary pressure may for example be performed using a tapping duct, which is connected to the secondary duct or the part of the softstart duct extending between the secondary duct and the choke means. The valve means may consist exclusively of the softstart valve. The softstart valve can be operated as a separate valve and for example also as a switching on valve within a so-called servicing device employed for conditioning the compressed air. In the case of a particularly advantageous design the valve means in addition to the softstart valve comprises a fluid distributor bearing the softstart valve and which is furthermore fitted with several control valves which are supplied from a distributor feed duct of the fluid distributor jointly with the pressure medium. The softstart valve is in this case so installed that its secondary duct communicates with the distributor feed duct and accordingly a controlled build up of pressure may take place in the distributor feed duct. in this case the primary duct may be joined with a distributor supply duct opening at the outer face of the fluid distributor, by way of which the connection with the primary pressure source may take place. Nevertheless there is the possibility of additionally connecting the pressure source directly with a corresponding opening of the primary duct on the softstart valve. In the following the invention will be described with reference to the accompanying drawings. Figure 1 is a perspective representation of a preferred embodiment with the valve means in accordance ■ with the invention fitted with a softstart valve. Figure 2 shows the valve means of figure 1 with the softstart valve in a cross section taken on the line II - II, the principal valve being illustrated on just assuming the home position. Figure 3 is a representation similar to that of figure 2, in which the principal valve is depicted on assuming the softstart position. Figure 4 is a representation like that of figure 2, the principal valve being shown on assuming the working position. In figures 2 through 4 the ducts extending within the softstart valve are partly represented only as dotted or continuous lines for the sake of presenting a better overall view. The continuous lines in this case represent duct currently under pressure. The valve means in the drawing generally referenced 6 is in the form of a valve cluster comprising an integral or, preferably, modular fluid distributor 7, which is fitted with several electrically operated control valves 8. The control valves 8 are seated on component mounting face, covered by them in the drawing, at which ducts open which extend in the fluid distributor 7, such ducts being joined with ducts, not illustratedin detail, of the control valves 8 in a known fashion. The ducts extending in the fluid distributor 7 include a distributor feed duct 12 extending along the fluid distributor 7 and also two parallel first and , respectively, second distributor relief ducts 13 and 14. These ducts 12, 13 and 14 are connected for fluid flow in the region of the above mentioned component mounting faces with each of the control valves 8. The distributor relief ducts 13 and 14 are venting ducts in the case of operation with compressed air. From each component mounting site there extends a first and a second distributor power duct 15 and 16 able to be joined to loads, which are not illustrated, which are for example drives to be operated by fluid power. The action of fluid in the distributor power ducts 15 and 16 is set by the control valves 8 which are able to be controlled by a merely diagrammatically indicated electrical signal transmission means 17 extending in the fluid distributor 7. The fluid distributor 7 is provided with at least one softstart valve 21 in addition to the control valves 8. Its preferred design is more particularly indicated in figures 2 through 4. It is conveniently mounted in a preferably removable manner on a component mounting site 18 located externally on the fluid distributor 7. However direct integration in the fluid distributor 7 would be possible as well. The component mounting site 18 for the softstart valve 21 conveniently adjoins the row of juxtaposed component mounting sites for the control valves 8, more particularly in a common plane. On the component mounting site 18 for the softstart valve 21 there is a similar configuration of openings of the ducts extending in the fluid distributor 7, i.e. similar to the component mounting sites for the control valves 8. Accordingly the component mounting site 18 may be selectively employed for mounting a softstart valve 21 or with at least one control valve 8. In the case of need there may be an intermediate adapter. In the case of mounting a softstart valve 21 the one distributor power duct 15 will function as a distributor supply duct 22, via which the pressure medium required for the operation of the valve means can be supplied from outside. The distributor supply duct 22 terminates at the side, which is opposite to the component mounting site 18, with a feed opening 2 3 on a readily accessible outer face of the fluid distributor 7. At this feed opening 23 a fluid line may be connected using suitable attachment means to provide a connection with a pressure source, which supplies the said pressure medium. The supplied pressure medium is at a pressure as set by the pressure source or a pressure regulator placed downstream from same, such pressure following being named the primary pressure. Given a suitable design of the softstart valve 21 it would also be possible the other distributor power duct 16 to be employed as an alternative or in addition as a distributor supply duct 22. With the aid of the softstart valve 21 on putting the valve means 6 into operation it is possible to provide for a slow and gentle build up of pressure in the distributor feed duct 12 supplying the control valves 8. The distributor feed duct 12 is not supplied directly via a connection opening in a conventional manner from an outer face of the fluid distributor 7, but from the distributor supply duct 22 via the softstart valve 21. The softstart valve 21 is functionally divided up into several individual valves, which nevertheless are collected together as a subassembly which may be handled as a single part. The softstart valve 21 comprises for this purpose a principal valve 24, a pilot valve 25 and a switch over valve 26. The softstart valve 21 is activated by the pilot valve 25, which on the one hand can act directly and on the other hand may act indirectly (via the intermediately placed switch over valve) for fluid flow on the principal valve 24 in order to set one of in all three possible switching positions of the principal valve 24. The pilot valve 25 is of the type able to be electrically operated and possesses an electrical interface 27 via which it may be supplied with the necessary electrical actuating signals. As a departure from the working example with the electrical supply of the pilot valve 25 independent of the electrical signal transmission means, the pilot valve 25 may be connected in a modification of the invention also with the electrical signal transmission means 17. The principal valve 24 possesses an elongated housing 28 in which a.n elongated cavity is formed defining a valve member space 32 is formed. The valve member space 32 contains an elongated principal valve member 33 sliding in the direction of its longitudinal axis 21 linearly. On the basis of the resulting switch over movement 34 indicated by the double arrow the principal valve member 33 and accordingly the principal valve 24 may be switched over between three in all switching positions to be explained below. The principal valve member 33 is more particularly designed like a valve spool. Owing to the sealing means 35 arranged in the valve member space 32 in a manner fixed in relation to the housing, and for example in the form of annular sealing elements arranged with an axial clearance between them, and coaxially surrounding the principal valve member 33, the valve member space 32 is divided up into several sequentially placed portions 36a, 36b and 36c, from each of which respectively one valve duct extends through the valve housing. These valve ducts comprise a primary duct 1 communicating with the distributor supply duct 22, a secondary duct 2 communicating with the distributor feed duct 12 and a softstart duct 3 connected within the valve housing 23 with the secondary duct 2. The connection with the distributor supply duct 22 and the distributor feed duct 12 is produced because the primary duct 1 and the secondary duct 2 open at an installation face 37 externally arranged on the valve housing 28, at which the softstart valve 21 is arranged on the component mounting face 18. The duct openings on the installation face 18 are so distributed that they are in line with the correct correspondence with the openings of the distributor ducts. The first portion 36a, communicating with the primary duct l of the valve member space 32 lies axially between the second portion 36b, communicating with the secondary duct 2 and the third portion 36c with the softstart duct 3. Choke means 38 are placed of the softstart duct 3. They delimit the flow of fluid through the softstart duct 3 in accordance with the predetermined intensity of choking. Preferably they are adjustable as regards the intensity of choking so that the rate of flow in the softstart duct 3 may be varied. In the particular example the choke means 3 8 have a choke screw 38a accessible from an outer face of the valve housing 28. The length portion lying within the portions 36a, 36b and 36c of the principal valve member 33 constitutes a control portion 42 cooperating with the sealing means 35. It is stepped along its length and comprises altematingly arranged regions with a larger and smaller diameter. Dependent on whether a region with a larger or smaller diameter is axially aligned with the sealing elements, the respective regions, arranged axially on either side of the corresponding sealing element, of the valve member space 32 of the valve member space 32 will be connected together or separated as regards fluid flow. Adjoining the control portion 32 on. the side of the third portion 36c there is a drive portion 43 of the principal valve member 33. This is engaged by a return spring means 44, which biases the principal valve member 33 toward a home position as indicated in figure 2. The return spring means 44 is preferably in the form of a compression spring means, which preferably coaxially surrounds the drive portion 43. At the one end it bears - on the right end in the drawing - against the valve housing 28b and at the other end - on the left in the drawing - against the principal valve member 33. Accordingly the principal valve member 33 is constantly urged by the spring force to the left in the drawing. While performing its switch over movement 43 the principal valve member may be selectively positioned in the home position as in figure 2, in the softstart position depicted in figure 3 or in the working position illustrated in figure4. These positions differ as regards different placement in circuit of the valve means 2 and 3 by the control portion 42. In the home position depicted in figure 2 the secondary duct is separated from the adjacent primary duct 1. The primary duct 1 conducts, just like the distributor feed duct 22 constantly communicating with it, a pressure medium subject to the primary pressure. It is an advantage if the secondary duct 2 is joined in the home position with a relief duct 4 of the principal valve 33. If the pressure medium is compressed air, as is the case with the working example, the relief duct 4 will constitute a venting duct opening at the outer face of the valve housing 28, such relief duct being connected with a muffler 45 if desired. It is convenient for the relief duct 4 to open as a coaxial extension of the valve member space 32 at a terminal side of the valve housing 28. Alternatively or in addition there is also the possibility to extend the relief duct as far as the installation face 37 so that it communicates with one of the distributor relief ducts 13 or 14 and an additional or exclusive relief of pressure may take place via the fluid distributor 2. The primary duct 1 is also separated from the softstart duct 3 in the home position. In the softstart position the secondary duct 2 is exclusively connected via the softstart duct 3 and accordingly via the choke means 38, with the primary duct 1. The connection is opened between the first and the third portion 36a and 36c. A direct connection between the primary duct 1 and the secondary duct 2 bypassing the softstart duct 3 does not exist. The secondary duct 2 is furthermore separated from the relief duct 4 as well. Finally in the working position depicted in figure 4 there is a direct connection between the primary duct 1 and the secondary duct 2, bypassing the choke means 38 and accordingly the softstart duct 3, via the directly connected first and second portions 36a and 36b of the valve member space 32. It is however possible to keep the connection via the softstart duct 3 as a parallel connection in addition, as is the case in the working embodiment. Via the direct connection a higher fluid flow rate between the primary duct 1 and the secondary duct 2 is possible than via the softstart duct 3. The relief duct 4 is still separated from all other valve ducts. The principal valve 24 has a first (46) and a second (47) actuating face, which respectively cooperate with the principal valve member 33. The first actuating face 46 is located on an actuating element 48 which is independent of the principal valve member 33 and which in the working example is like an actuating piston that is received axially following the drive portion 43 of the principal valve member 33 in the valve member space 32. The first actuating face 46 faces axially away from the principal valve member 33 and to the left in the drawing. The actuating element 48 is accommodated in a receiving chamber 52 (formed by the terminal portions of the valve member space 32) and able to slide in the direction of the longitudinal axis 31 of the principal valve member 33. It makes sealing contact with the peripheral wall thereof. The terminal faces of the accommodating chamber 52 constitute a first abutment face 53 facing the principal valve member 33 and an oppositely orientated second abutment face 54 for the actuating element 48, which delimits its setting displacement. In lieu of the actuating piston the actuating element 48 could for example also be designed in the form of an actuating diaphragm. The second actuating face 47 is arranged on the principal valve member 33 in an axially fixed fashion. Therefore it partakes in every linear movement of the principal valve member 3. It faces in the same direction as the first actuating face 46, i. e. in the present case away from the control portion 42. It is preferred for the second actuating face 47 to be fixedly arranged on the terminal face, facing the actuating element 48, of the principal valve member 33. In the working embodiment this is the case. When the principal valve member 33 is linearly shifted, its terminal portion, which has the second actuating element 47, may enter the receiving chamber 52 (figure 2). Furthermore the principal valve member 33 may assume the positions illustrated in figures 3 and 4 in which it comes completely out of the receiving chamber 52 and its terminal portion having the second actuating face 47 is located in a length portion 55 adjoining the accommodating chamber 52, the cross section of the chamber 32 being smaller than that of the accommodating chamber 52. Accordingly the second actuating face 47 is preferably smaller than the first actuating face 46. As long as the principal valve member 33 extends into the accommodating chamber 52 a transmission of force orientated in the direction of the switching movement 32 is possible between the principal valve member and the actuating element 48. These two parts however only loosely engage each other so that only thrust setting forces may be transmitted. On the other hand this provides the possibility for the principal valve member 33 being shifted clear of the actuating element 48 and moving away from it, there being a simultaneous change in the distance between the two actuating faces 46 and 47. In any case the principal valve member 33 possesses a working face 56 facing the actuating element 48 and more particularly constituted by the terminal face of the principal valve member 33, such face 56 being able to be acted on mechanically by the actuating element 48. The above mentioned return spring means 44 is located between, on the one hand, the two actuating faces 46 and 47 on the other hand the control portion 42 on the drive portion 43 of the principal valve member 33. For simplification of assembly of the return spring means 44 the principal valve member 33 may be made in several parts. Preferably at its terminal portion nearer the actuating element 4 8 it has a clipped on and more particularly swaged on and sleeve-like head piece 57 against which the return spring means 44 may bear and which with the aid of an annular seal 58 borne by it is able slide in the length portion 55 in the valve member space 32. The head piece 57 can have at least one portion of the second actuating face 47. The actuating element 48 divides up the accommodating chamber 52 into a first actuating chamber 62 on the side opposite to the principal valve member 33 and a second actuating chamber 63 lying on the side facing the principal valve member 33. The first actuating chamber 62 is separated from the actuating element 48 by the first abutment face 53. The second actuating chamber 63 possesses, axially opposite the actuating element 48, a rigid limiting wall, constituted by the second abutment face 54, and furthermore an axially moving delimiting wall, which is formed by the principal valve member 33 and respectively its second actuating face 47. Given a suitable position of the principal valve member 33 accordingly the second actuating chamber 63 may extend a little into the length portion 55, as is illustrated in figure 4. A fluid pilot duct 64 branching off the second portion 36b (which is connected with the primary duct 1) of the valve member space 32 opens at the other end into the first actuating chamber 62 . The pilot valve 65 is placed, on this pilot duct 64 so that the pilot duct 64 is divided up into a pilot feed duct 64a communicating with the primary duct l and a pilot power duct 64b communicating with the first actuating chamber 62. The pilot valve 25 is more particularly a 3/2 directional valve in a position to join the pilot power duct 64b either with the pilot feed duct 64a or with a pilot venting duct 65 serving for pressure relief. The latter can open directly into the atmosphere via the housing of the pilot valve 25, as is the case with the working example of the invention. Nevertheless it is possible to provide for venting by way of a distributor venting duct extending in the fluid distributor 7. The switch over valve 6 comprises a preferably linearly moving switch over valve member 67 able to move in the direction of the double arrow 66. A preferably mechanical spring means 68 produces a resilient force biasing the switch over valve member 67 toward a home position as depicted in figures 2 and 3. The starting position is set by the engagement of the switch over valve member 67 on an abutment face 72 on the housing. In lieu of the mechanical spring means 68 it would also be possible to employ a pneumatic spring means, and more particularly an air spring means. In common with the housing portion surrounding the switch over valve member 67 axially delimits a control chamber 73, which is continuously connected with the secondary duct 2 via a tapping duct 74, which extends through the softstart valve 21. This connection may be direct or via a port of the tapping duct 74 to the duct part, extending between the choke means 34 and the secondary duct 2, of the associated duct 3. Accordingly the current secondary pressure continuously obtains in the control chamber 73. This pressure exerts a switching over Fu opposing the force of the spring means 68. The switch over valve 68 may control the fluid flow through a switching over duct 75 by way of which the pilot power duct 64b is joined with the second actuating chamber 63. In the initial position of the switch over valve member 67 the connection is interrupted. If the switch over valve member 67 shifted by a sufficient switch over force F0 into the switch over position illustrated in figure 4, the fluid passage through the switch over duct 75 is open. A typical manner of operation of the valve means 6 is as follows. Let it be assumed that the pilot valve 25 is deactivated and the principal valve member 33 is in the home position. Accordingly the secondary duct 2 and the distributor feed duct 12 connected with it is free of pressure, via the feed opening 23 pressure medium at a primary pressure is supplied, which is also present in the pilot feed duct 64a. The two actuating chambers 62 and 63 are vented via the pilot valve 25. This home state is depicted in figure 2. For switching on the valve means 6 the pilot valve 25 is operated by the supply of an electrical control signal. The pilot valve 25 opens the passage through the pilot duct 64 so that a fluid pilot signal, corresponding to the primary pressure, is fed to the first actuating chamber 62 to act on the actuating face 46. Owing to the resulting setting force the actuating element 48 is shifted until it abuts the second abutment face 54, it entraining the principal valve member 33 and overcoming the spring force of the return spring means 44. When the actuating element 48 reaches the second abutment face 54, the principal valve member 33 will be in the. softstart position depicted in figure 3. The switch over valve member 67 in the initial position will then keep the second actuating chamber 64 separate from the pilot duct 64. Starting with the switching over into the softstart position there comes a softstart phase lasting a certain time. It is characterized in that via the opened softstart duct 3 a choked flow of pressure medium will enter the secondary duct 2 so that the secondary pressure therein will gradually increase. The gradient of such pressure increase may be controlled by setting the choke means 38. Via the tapping duct 74 the current secondary pressure will also obtain in the control chamber 73 of the switch over valve 26. with the increase in the secondary pressure the switching over force Fu will also increase, this having no effect as long as the threshold value set by the spring means 68 is not reached. When this threshold value is reached the softstart phase will end. The switching over force Fu is now sufficient to shift the switch over valve member 62 into the switch over setting illustrated in figure 4, this meaning that the fluid pilot signal will, via the now opened switching over duct 75, also take effect in the second actuating chamber 63 and therefore at the second actuating face 47. As a consequence of this the principal valve member 33 will be further shifted into the working position as illustrated in figure 4, the actuating element 48 then not moving any further. Since the cross section of the length portion 55 is smaller than that of the first actuating chamber 62, a differential force will act at the actuating element 4 8 holding same in engagement with the second abutment face 54. Owing to the switching over into the working position the secondary duct 2 is supplied with pressure medium via the large cross section opened by the principal valve member 63 with the result that the secondary pressure promptly reaches the level of the primary pressure. In the working embodiment the pressure obtaining in the secondary duct 2 is immediately switched to the switch over valve 26 as the control pressure providing the switching over force. Alternatively there is nevertheless the possibility of designing the switch over valve 26 to be electrically operated, the electrical switch over being generated with the cooperation of a pressure sensor or pressure sensor, which is responsive to the secondary pressure. In order to return to the home position only the pilot valve 25 is to be turned off so that the pilot working duct 64b" is vented. The return spring means 44 then shifts the main valve member 33 back into the home position. The spring means 68 is preferably made adjustable as regards its spring force. For this purpose a rotatable head 76 or some other suitable manual control may be present. One advantage of the above described valve design lies in the lack of sensitivity as regards pressure fluctuations in the primary duct 1 or the secondary duct 2. Should owing to a pressure drop the switching over force Fu drop so far that the switch over valve 26 goes over into the initial position, this will be without effect on the working position of the main valve member 13, seeing that the pilot fluid present in the second actuating chamber 63 remains captive and can not escape. The valve means 6 may be operated both with a gaseous and also with a liquid medium. Preferably compressed air comes into question. Claims 1. A valve means having a softstart function comprising: a softstart valve (21) having the following features: - a principal valve (24) able to be switched over between a home position, a softstart position and a working position, said principal valve in the home position separates a secondary duct (2) from a primary duct (1) conducting pressure medium subject to a primary pressure, said principal valve in the softstart position connects the secondary duct (2) via a softstart duct (3) containing a choke means (38), with the primary duct (1), and said principal valve in the working position by bypassing the choke means (38) opens a connection between the secondary duct (2) and the primary duct (1), - a pilot valve (25) provided for influencing the switching position of the principal valve (24), on whose operation a fluid pilot signal is generated acting on a first actuating face {46} of the principal valve (24) in order to switch over the principal valve (24) out of the home position and into the softstart position, - and a switch over valve (26) able to be operated by the secondary pressure obtaining in the secondary duct (2), which valve at a predetermined level of the secondary pressure switches over the fluid pilot signal, produced by the pilot valve (25) to a second actuating face (47) of the principal valve (24) in order to switch over the principal valve (24) out of the softstart position into the working position. 2. The valve means in accordance with claim 1, characterized in that the secondary duct (2) is connected with a relief duct (4) in the home position of the principal valve (24) . 3. The valve means in accordance with claim 1 or with claim 2, characterized in that the choke means (38) are designed to be adjustable as regards choking intensity. 4. The valve means in accordance with any one of the claims 1 through 3, characterized in that the principal valve (24), the pilot valve (25) and the switch over valve (26) are combined together as a single subassembly. 5. The valve means in accordance with any one of the claims 1 through 4, characterized in that the pilot valve (25) is a solenoid valve. 6. The valve means in accordance with any one of the claims 1 through 5, characterized in that the two actuating faces {46 and 47) face in the same direction. 7. The valve means in accordance with any one of the claims 1 through 6, characterized in that the three switching positions of the principal valve (24) are set by corresponding switching positions of a movable principal valve member (33), the first and the second actuating face (46 and 47) being each designed to cooperate in a driving manner with the principal valve member (33). 8. The valve means in accordance with claim 7, characterized in that the first actuating face (46) is formed on an actuating element (48), formed separately from the principal valve member (33), such actuating element (48) on being acted upon by the fluid pilot signal being able to be shifted as far as abutting on an engagement face (54) with a simultaneous entrainment of the principal valve member (33) wherein said engagement face is setting the softstart position, the principal valve member (33) being shifted away from the actuating element (48) when it is subsequently moved on further as far as the working position by the action of fluid on the second actuating face (47). 3. The valve means in accordance with claim 8, characterized in that the actuating element (48) is arranged axially following the linearly sliding principal valve member (33) and loosely engages the principal valve member (33) in a fashion only allowing transmittal of thrust forces. 10. The valve means in accordance with claim 8 or with claim 9, characterized in that the actuating element (48) is piston-like in configuration. 11. The valve means in accordance with any one of the claims 7 through 10, characterized in that the second actuating face (47) is arranged fixedly on the main valve member (33) . 12. The valve means in accordance with claim 11 in conjunction with any one of the claims 8 through 10, characterized in that the second actuating face (47) moves away from the first actuating face (46) when the principal valve (24) is switched over out of the softstart position into the working position. 13. The valve means in accordance with any one of the claims 7 through 12, characterized by a return spring means (44) biasing the principal valve member (33) into the home position. 14. The valve means in accordance with claim 13, characterized in that the return spring means (44) is arranged coaxially on the principal valve member (33) axially between on the one hand the two actuating faces (46 and 47) and on the other hand the control portion (42) of the principal valve member (33) which is setting the switching positions. 15. The valve means in accordance with any one of the claims 7 through 14, characterized in that the first actuating face (46) delimits a first actuating chamber (62) which communicates with a pilot duct (64) supplying the fluid pilot signal and controlled by the pilot valve (25). 16. The valve means in accordance with any one of the claims 7 through 15, characterized in that the second actuating face (47) delimits a second actuating chamber (63), which communicates with a switch over duct (75) which communicates with a pilot duct {64} supplying the fluid pilot signal and is controlled by the pilot valve (25) and in which the switch over valve (26) is placed. 17. The valve means in accordance with a.ny one of the claims 1 through 16, characterized in that the switch over valve (26) comprises a switch over valve member (67) biased by a spring force toward a starting position and biased in the opposite direction by a switch over force which depends on the secondary pressure present in the secondary duct (2). 18. The valve means in accordance with claim 17, characterized in that the switch over valve member (67) governs the passage of fluid through a switch over duct (75), which on the one end is acted upon by the fluid pilot signal of the pilot valve and on the other end leads to the second actuating face (47) with the result that the passage of fluid is prevented in the starting position of the switch over valve member (67) and is opened when the switch over valve member (67) is shifted into a switch over position owing to reaching a secondary pressure of a predetermined level. 19. The valve means in accordance with claim 17 or claim 18, characterized in that the spring force is provided by mechanical spring means (68), which more especially are able to be adjusted as regards their force. 20. The valve means in accordance with any one of the claims 1 through 19, characterized in that the secondary pressure obtaining in the secondary duct (2) is directly switched to the switch over valve (26) as a control pressure serving for producing the switch over force. 21. The valve means in accordance with any one of the claims 1 through 20, characterized by a fluid distributor (7) fitted with several control valves (8), which has a distributor feed duct (12) and at least one distributor relief duct (13 and 14}, which are respectively connected with the control valves (8) for fluid flow, the secondary duct (2) being connected with the distributor feed duct (12) and the primary duct (1) being connected with a distributor supply duct (22) opening at an outer face of the fluid distributor (7) . 22. The valve means in accordance claim 21, characterized in that the fluid distributor (7) possesses several component mounting sites, from which respectively two distributor power ducts (15 and 16) extend, which pass through the fluid distributor (7), and said component mounting sites at least in part being able to be selectively fitted with a control valve (8) or with a softstart valve (21), wherein in the case of a component mounting site being fitted with a softstart valve

Full Text

-- VALVE DEVICE HAVING A SOFT START FUNCTION --
The invention relates to a valve means with a softstart function that is to say a function rendering possible a gradual and not abrupt build up of pressure on the secondary side.
The German patent publication DE 91 05 458 Ul discloses such a valve means, which has a softstart valve made up of several individual valves. A shut off valve designed as a valve with two positions is placed on the connection between a primary duct connected with a pressure source and a secondary duct connected with the loads to be supplied and may close the connection (home position) or open it (working position). Switching over into the working position is caused within a certain period of time after operation of a pilot valve which is placed on a softstart duct bypassing the main valve which furthermore has a choke means. By way of a branch from the softstart duct moreover the secondary pressure obtaining in the secondary duct is switched to the main valve as a control pressure effective toward the working position.
As from the activation of the pilot valve the secondary duct is supplied via the softstart duct in a choked manner with pressure medium from the primary duct. Accordingly in the secondary duct there is a gradual increase in pressure. When the secondary pressure has reached a predetermined level the main valve switches over into the working position with the result that then the main valve is supplied via the larger flow cross section of the main valve until the secondary pressure finally reaches the level of the primary pressure.
In the known valve means it is possible for a brief drop in pressure, due to pressure fluctuations, in the secondary duct to cause the main valve to switch over into the home position so that the system is accordingly back in the softstart mode for some time. This may entail substantial

impairments in function, because the connected loads cannot be supplied with the necessary amount of fluid for a short time. Furthermore a relatively large size of pilot valve is required in order to ensure the greater flow rate which may in some circumstances be required even in the softstart phase, something which all in all means large dimensions of the softstart valve.
A softstart device disclosed in the German patent publication DE 20 2004 015 468 Ul is similarly designed, A shut-off valve is able to be switched over by the gradually increasing secondary pressure from a shut home position into an open working position. The build up of pressure on the secondary side is predetermined by a choke means placed on a softstart duct bypassing the shut off valve. The device is started by the simultaneous operation of two further valve means placed on the duct, by which furthermore venting of the softstart device is possible.
The US patent 5,669,422 discloses a softstart valve with a valve able to be switched over between three positions. The switching over from the home position into a softstart position is caused by a pilot valve. Switching over from the softstart position into a working position is entailed by the gradually increasing secondary pressure which as from the softstart position continuously acts on the principal valve.
One object of the present invention is to provide a valve means, having a reliably operating but nevertheless compactly dimensioned softstart means.
This object is achieved with a valve means having a softstart valve comprising the following features:
- a principal valve able to be switched over between a home position, a softstart position and a working position, and which in the home position separates a secondary duct from a primary duct conducting pressure medium subject to a primary pressure, which in the softstart position joins the secondary duct, via a

softstart duct containing choke means, with the primary-duct and which in the working position by bypassing the choke means opens a connection between the secondary duct and the primary duct
- a pilot valve provided for influencing the switching position of the principal valve, on whose operation a fluid pilot signal is generated acting on a first actuating face of the principal valve in order to switch over the principal valve out of the home position and into the softstart position,
- and a switch over valve able to be operated by the secondary pressure obtaining in the secondary duct, which valve at a predetermined level of the secondary pressure switches over the fluid pilot signal, produced by the pilot valve to a second actuating face of the principal valve in order to switch over the principal valve out of the softstart position into the working position.
The principal valve of the softstart valve is accordingly designed in the form of an at least three position valve, which in addition to the home position and the working position may also assume a softstart position responsible for the softstart phase. While in the prior art the softstart fluid flow is conducted through the pilot valve bypassing the principal valve, in accordance with the invention it flows through the principal valve without recjuiring any direct control by the pilot valve. The preferably electrically operated pilot valve is responsible for the diverse switching positions of the principal valve in conjunction with the additional switching over valve. The fluid signal valve produced by the pilot valve switches the principal valve into the softstart position. When after a certain period of time the secondary pressure has reached the switch over threshold, it then causes such an actuation of the switch over valve that the fluid pilot signal is applied to a further actuating face

so that the principal valve is switched over from the soffcstart position into the working position ensuring a higher flow rate.
The switch over valve is preferably fluid-operated, the secondary pressure being applied to it directly as a control pressure. The switch over valve may in this case be for instance operate as a sort of pressure bridge. As an alternative a merely indirect activation of the switch over valve by the secondary pressure would be possible by employing an electrically activated switch over valve, whose switch over signal is generated with the aid of a pressure sensor or pressure switch responsive to the secondary pressure. The latter feature renders possible a particularly simple variation of the switch over threshold.
Since the secondary pressure itself does not act directly as an actuating pressure on the principal valve, there is a pilot signal leading to uncoupling from the pilot signal supplying the switch over force for the principal valve. Accordingly a circuit arrangement is possible in which pressure fluctuations occurring in the working position in the primary duct and/or of the secondary duct do not affect the switching position of the principal valve. This renders possible trouble-free operation until the pilot valve is turned off.
Further advantageous developments of the invention are defined in the dependent claims.
It is convenient to so design the principal valve that in its home position it entails the pressure relief in the secondary duct, that is to say in a pneumatic application a venting of the secondary duct. The pressure relief by way of the principal valve makes unnecessary the use of separate venting valve or venting through the pilot valve.
The choke means responsible for the speed of a pressure build-up in the secondary duct are preferably adjustable. For

instance, the choke means can comprise a choke screw screwed into the Valve housing to an adjustable degree.
The principal valve, the pilot valve and the switch over valve are preferably combined together as a subassembly constituting the softstart valve. This provides for a simplification of handling during installation and removal.
The pilot valve will more particularly be a solenoid valve. Other electrically activated valves are nevertheless able to be employed, as for example piezoelectric valves or electrostatic valves.
It is convenient for the two actuating faces of the principal valve to face in the same direction. The switch over from the home position into the softstart position and from the softstart position into the working position occurs in this case with the same direction of switch over movement; such movement preferably being linear.
Preferably the principal valve possesses a main valve member able to be positioned in a corresponding number of switching positions to set its switching positions, more particularly in the form of a valve spool. For switching over the first and the second actuating face cooperate together with the main valve member in a driving manner.
While the second actuating face responsible for switching over into the working position is preferably arranged stationarily on the main valve member, the first actuating face, responsible for the switching over into the softstart position, is preferably provided on an actuating element separate from the main valve member. This actuating element is so uncoupled from the main valve member that the latter may be switched over without entraining the actuating element into the working position. Therefore while during switching over from the home position into the softstart position preferably both actuating faces are shifted jointly, during switching over into the working position the first actuating element lags behind and the second actuating face moves away from it.

The reason for the above mentioned timing is conveniently the presence of an abutment face arranged in the path of motion of the actuating element, which defines the softstart position.
The actuating element is preferably designed in the form of an actuating piston. Alternatively however a design in the form of an actuating diaphragm would also be possible.
Preferably the principal valve member is biased by a preferably mechanical return spring means into the home position. Following switching over into the softstart position the return spring means is compressed to a certain degree, the degree of compression being further increased until the working position is reached. After deactivation of the pilot valve the return spring means ensures a return in the principal valve member into the home position.
The action of the pilot pressure on the first actuating face preferably takes place directly via a pilot control duct under the control of the pilot valve. The action on the second actuating face preferably best takes place via a switch over duct branching off from the pilot control duct, the switch over valve being placed on the switching over duct and being able to shut or open the switching over duct.
The switch over valve preferably comprises a moving switch over valve member. The same is controlled and operated on the basis of the secondary pressure. Direct actuation, if required, by the secondary pressure may for example be performed using a tapping duct, which is connected to the secondary duct or the part of the softstart duct extending between the secondary duct and the choke means.
The valve means may consist exclusively of the softstart valve. The softstart valve can be operated as a separate valve and for example also as a switching on valve within a so-called servicing device employed for conditioning the compressed air.

In the case of a particularly advantageous design the valve means in addition to the softstart valve comprises a fluid distributor bearing the softstart valve and which is furthermore fitted with several control valves which are supplied from a distributor feed duct of the fluid distributor jointly with the pressure medium. The softstart valve is in this case so installed that its secondary duct communicates with the distributor feed duct and accordingly a controlled build up of pressure may take place in the distributor feed duct. in this case the primary duct may be joined with a distributor supply duct opening at the outer face of the fluid distributor, by way of which the connection with the primary pressure source may take place. Nevertheless there is the possibility of additionally connecting the pressure source directly with a corresponding opening of the primary duct on the softstart valve.
In the following the invention will be described with reference to the accompanying drawings.
Figure 1 is a perspective representation of a preferred embodiment with the valve means in accordance ■ with the invention fitted with a softstart valve. Figure 2 shows the valve means of figure 1 with the
softstart valve in a cross section taken on the line II - II, the principal valve being illustrated on just assuming the home position. Figure 3 is a representation similar to that of figure 2, in which the principal valve is depicted on assuming the softstart position. Figure 4 is a representation like that of figure 2, the principal valve being shown on assuming the working position. In figures 2 through 4 the ducts extending within the softstart valve are partly represented only as dotted or continuous lines for the sake of presenting a better overall

view. The continuous lines in this case represent duct currently under pressure.
The valve means in the drawing generally referenced 6 is in the form of a valve cluster comprising an integral or, preferably, modular fluid distributor 7, which is fitted with several electrically operated control valves 8.
The control valves 8 are seated on component mounting face, covered by them in the drawing, at which ducts open which extend in the fluid distributor 7, such ducts being joined with ducts, not illustratedin detail, of the control valves 8 in a known fashion.
The ducts extending in the fluid distributor 7 include a distributor feed duct 12 extending along the fluid distributor 7 and also two parallel first and , respectively, second distributor relief ducts 13 and 14. These ducts 12, 13 and 14 are connected for fluid flow in the region of the above mentioned component mounting faces with each of the control valves 8. The distributor relief ducts 13 and 14 are venting ducts in the case of operation with compressed air.
From each component mounting site there extends a first and a second distributor power duct 15 and 16 able to be joined to loads, which are not illustrated, which are for example drives to be operated by fluid power. The action of fluid in the distributor power ducts 15 and 16 is set by the control valves 8 which are able to be controlled by a merely diagrammatically indicated electrical signal transmission means 17 extending in the fluid distributor 7.
The fluid distributor 7 is provided with at least one softstart valve 21 in addition to the control valves 8. Its preferred design is more particularly indicated in figures 2 through 4. It is conveniently mounted in a preferably removable manner on a component mounting site 18 located externally on the fluid distributor 7. However direct integration in the fluid distributor 7 would be possible as well.

The component mounting site 18 for the softstart valve 21 conveniently adjoins the row of juxtaposed component mounting sites for the control valves 8, more particularly in a common plane.
On the component mounting site 18 for the softstart valve 21 there is a similar configuration of openings of the ducts extending in the fluid distributor 7, i.e. similar to the component mounting sites for the control valves 8. Accordingly the component mounting site 18 may be selectively employed for mounting a softstart valve 21 or with at least one control valve 8. In the case of need there may be an intermediate adapter.
In the case of mounting a softstart valve 21 the one distributor power duct 15 will function as a distributor supply duct 22, via which the pressure medium required for the operation of the valve means can be supplied from outside. The distributor supply duct 22 terminates at the side, which is opposite to the component mounting site 18, with a feed opening 2 3 on a readily accessible outer face of the fluid distributor 7. At this feed opening 23 a fluid line may be connected using suitable attachment means to provide a connection with a pressure source, which supplies the said pressure medium. The supplied pressure medium is at a pressure as set by the pressure source or a pressure regulator placed downstream from same, such pressure following being named the primary pressure.
Given a suitable design of the softstart valve 21 it would also be possible the other distributor power duct 16 to be employed as an alternative or in addition as a distributor supply duct 22.
With the aid of the softstart valve 21 on putting the valve means 6 into operation it is possible to provide for a slow and gentle build up of pressure in the distributor feed duct 12 supplying the control valves 8. The distributor feed duct 12 is not supplied directly via a connection opening in a

conventional manner from an outer face of the fluid distributor 7, but from the distributor supply duct 22 via the softstart valve 21.
The softstart valve 21 is functionally divided up into several individual valves, which nevertheless are collected together as a subassembly which may be handled as a single part. The softstart valve 21 comprises for this purpose a principal valve 24, a pilot valve 25 and a switch over valve 26.
The softstart valve 21 is activated by the pilot valve 25, which on the one hand can act directly and on the other hand may act indirectly (via the intermediately placed switch over valve) for fluid flow on the principal valve 24 in order to set one of in all three possible switching positions of the principal valve 24. The pilot valve 25 is of the type able to be electrically operated and possesses an electrical interface 27 via which it may be supplied with the necessary electrical actuating signals. As a departure from the working example with the electrical supply of the pilot valve 25 independent of the electrical signal transmission means, the pilot valve 25 may be connected in a modification of the invention also with the electrical signal transmission means 17.
The principal valve 24 possesses an elongated housing 28 in which a.n elongated cavity is formed defining a valve member space 32 is formed. The valve member space 32 contains an elongated principal valve member 33 sliding in the direction of its longitudinal axis 21 linearly. On the basis of the resulting switch over movement 34 indicated by the double arrow the principal valve member 33 and accordingly the principal valve 24 may be switched over between three in all switching positions to be explained below. The principal valve member 33 is more particularly designed like a valve spool.
Owing to the sealing means 35 arranged in the valve member space 32 in a manner fixed in relation to the housing,

and for example in the form of annular sealing elements arranged with an axial clearance between them, and coaxially surrounding the principal valve member 33, the valve member space 32 is divided up into several sequentially placed portions 36a, 36b and 36c, from each of which respectively one valve duct extends through the valve housing. These valve ducts comprise a primary duct 1 communicating with the distributor supply duct 22, a secondary duct 2 communicating with the distributor feed duct 12 and a softstart duct 3 connected within the valve housing 23 with the secondary duct 2. The connection with the distributor supply duct 22 and the distributor feed duct 12 is produced because the primary duct 1 and the secondary duct 2 open at an installation face 37 externally arranged on the valve housing 28, at which the softstart valve 21 is arranged on the component mounting face 18. The duct openings on the installation face 18 are so distributed that they are in line with the correct correspondence with the openings of the distributor ducts.
The first portion 36a, communicating with the primary duct l of the valve member space 32 lies axially between the second portion 36b, communicating with the secondary duct 2 and the third portion 36c with the softstart duct 3.
Choke means 38 are placed of the softstart duct 3. They delimit the flow of fluid through the softstart duct 3 in accordance with the predetermined intensity of choking. Preferably they are adjustable as regards the intensity of choking so that the rate of flow in the softstart duct 3 may be varied.
In the particular example the choke means 3 8 have a choke screw 38a accessible from an outer face of the valve housing 28.
The length portion lying within the portions 36a, 36b and 36c of the principal valve member 33 constitutes a control portion 42 cooperating with the sealing means 35. It is stepped along its length and comprises altematingly arranged

regions with a larger and smaller diameter. Dependent on whether a region with a larger or smaller diameter is axially aligned with the sealing elements, the respective regions, arranged axially on either side of the corresponding sealing element, of the valve member space 32 of the valve member space 32 will be connected together or separated as regards fluid flow.
Adjoining the control portion 32 on. the side of the third portion 36c there is a drive portion 43 of the principal valve member 33. This is engaged by a return spring means 44, which biases the principal valve member 33 toward a home position as indicated in figure 2.
The return spring means 44 is preferably in the form of a compression spring means, which preferably coaxially surrounds the drive portion 43. At the one end it bears - on the right end in the drawing - against the valve housing 28b and at the other end - on the left in the drawing - against the principal valve member 33. Accordingly the principal valve member 33 is constantly urged by the spring force to the left in the drawing.
While performing its switch over movement 43 the principal valve member may be selectively positioned in the home position as in figure 2, in the softstart position depicted in figure 3 or in the working position illustrated in figure4. These positions differ as regards different placement in circuit of the valve means 2 and 3 by the control portion 42.
In the home position depicted in figure 2 the secondary duct is separated from the adjacent primary duct 1. The primary duct 1 conducts, just like the distributor feed duct 22 constantly communicating with it, a pressure medium subject to the primary pressure.
It is an advantage if the secondary duct 2 is joined in the home position with a relief duct 4 of the principal valve 33. If the pressure medium is compressed air, as is the case

with the working example, the relief duct 4 will constitute a venting duct opening at the outer face of the valve housing 28, such relief duct being connected with a muffler 45 if desired.
It is convenient for the relief duct 4 to open as a coaxial extension of the valve member space 32 at a terminal side of the valve housing 28. Alternatively or in addition there is also the possibility to extend the relief duct as far as the installation face 37 so that it communicates with one of the distributor relief ducts 13 or 14 and an additional or exclusive relief of pressure may take place via the fluid distributor 2.
The primary duct 1 is also separated from the softstart duct 3 in the home position.
In the softstart position the secondary duct 2 is exclusively connected via the softstart duct 3 and accordingly via the choke means 38, with the primary duct 1. The connection is opened between the first and the third portion 36a and 36c. A direct connection between the primary duct 1 and the secondary duct 2 bypassing the softstart duct 3 does not exist. The secondary duct 2 is furthermore separated from the relief duct 4 as well.
Finally in the working position depicted in figure 4 there is a direct connection between the primary duct 1 and the secondary duct 2, bypassing the choke means 38 and accordingly the softstart duct 3, via the directly connected first and second portions 36a and 36b of the valve member space 32. It is however possible to keep the connection via the softstart duct 3 as a parallel connection in addition, as is the case in the working embodiment. Via the direct connection a higher fluid flow rate between the primary duct 1 and the secondary duct 2 is possible than via the softstart duct 3.
The relief duct 4 is still separated from all other valve ducts.

The principal valve 24 has a first (46) and a second (47) actuating face, which respectively cooperate with the principal valve member 33.
The first actuating face 46 is located on an actuating element 48 which is independent of the principal valve member 33 and which in the working example is like an actuating piston that is received axially following the drive portion 43 of the principal valve member 33 in the valve member space 32. The first actuating face 46 faces axially away from the principal valve member 33 and to the left in the drawing.
The actuating element 48 is accommodated in a receiving chamber 52 (formed by the terminal portions of the valve member space 32) and able to slide in the direction of the longitudinal axis 31 of the principal valve member 33. It makes sealing contact with the peripheral wall thereof. The terminal faces of the accommodating chamber 52 constitute a first abutment face 53 facing the principal valve member 33 and an oppositely orientated second abutment face 54 for the actuating element 48, which delimits its setting displacement.
In lieu of the actuating piston the actuating element 48 could for example also be designed in the form of an actuating diaphragm.
The second actuating face 47 is arranged on the principal valve member 33 in an axially fixed fashion. Therefore it partakes in every linear movement of the principal valve member 3. It faces in the same direction as the first actuating face 46, i. e. in the present case away from the control portion 42.
It is preferred for the second actuating face 47 to be fixedly arranged on the terminal face, facing the actuating element 48, of the principal valve member 33. In the working embodiment this is the case.
When the principal valve member 33 is linearly shifted, its terminal portion, which has the second actuating element 47, may enter the receiving chamber 52 (figure 2).

Furthermore the principal valve member 33 may assume the positions illustrated in figures 3 and 4 in which it comes completely out of the receiving chamber 52 and its terminal portion having the second actuating face 47 is located in a length portion 55 adjoining the accommodating chamber 52, the cross section of the chamber 32 being smaller than that of the accommodating chamber 52. Accordingly the second actuating face 47 is preferably smaller than the first actuating face 46.
As long as the principal valve member 33 extends into the accommodating chamber 52 a transmission of force orientated in the direction of the switching movement 32 is possible between the principal valve member and the actuating element 48. These two parts however only loosely engage each other so that only thrust setting forces may be transmitted. On the other hand this provides the possibility for the principal valve member 33 being shifted clear of the actuating element 48 and moving away from it, there being a simultaneous change in the distance between the two actuating faces 46 and 47.
In any case the principal valve member 33 possesses a working face 56 facing the actuating element 48 and more particularly constituted by the terminal face of the principal valve member 33, such face 56 being able to be acted on mechanically by the actuating element 48. The above mentioned return spring means 44 is located between, on the one hand, the two actuating faces 46 and 47 on the other hand the control portion 42 on the drive portion 43 of the principal valve member 33.
For simplification of assembly of the return spring means 44 the principal valve member 33 may be made in several parts. Preferably at its terminal portion nearer the actuating element 4 8 it has a clipped on and more particularly swaged on and sleeve-like head piece 57 against which the return spring means 44 may bear and which with the aid of an annular seal 58 borne by it is able slide in the length portion 55 in the

valve member space 32. The head piece 57 can have at least one portion of the second actuating face 47.
The actuating element 48 divides up the accommodating chamber 52 into a first actuating chamber 62 on the side opposite to the principal valve member 33 and a second actuating chamber 63 lying on the side facing the principal valve member 33. The first actuating chamber 62 is separated from the actuating element 48 by the first abutment face 53. The second actuating chamber 63 possesses, axially opposite the actuating element 48, a rigid limiting wall, constituted by the second abutment face 54, and furthermore an axially moving delimiting wall, which is formed by the principal valve member 33 and respectively its second actuating face 47. Given a suitable position of the principal valve member 33 accordingly the second actuating chamber 63 may extend a little into the length portion 55, as is illustrated in figure 4.
A fluid pilot duct 64 branching off the second portion 36b (which is connected with the primary duct 1) of the valve member space 32 opens at the other end into the first actuating chamber 62 . The pilot valve 65 is placed, on this pilot duct 64 so that the pilot duct 64 is divided up into a pilot feed duct 64a communicating with the primary duct l and a pilot power duct 64b communicating with the first actuating chamber 62.
The pilot valve 25 is more particularly a 3/2 directional valve in a position to join the pilot power duct 64b either with the pilot feed duct 64a or with a pilot venting duct 65 serving for pressure relief. The latter can open directly into the atmosphere via the housing of the pilot valve 25, as is the case with the working example of the invention. Nevertheless it is possible to provide for venting by way of a distributor venting duct extending in the fluid distributor 7.
The switch over valve 6 comprises a preferably linearly moving switch over valve member 67 able to move in the

direction of the double arrow 66. A preferably mechanical spring means 68 produces a resilient force biasing the switch over valve member 67 toward a home position as depicted in figures 2 and 3. The starting position is set by the engagement of the switch over valve member 67 on an abutment face 72 on the housing. In lieu of the mechanical spring means 68 it would also be possible to employ a pneumatic spring means, and more particularly an air spring means.
In common with the housing portion surrounding the switch over valve member 67 axially delimits a control chamber 73, which is continuously connected with the secondary duct 2 via a tapping duct 74, which extends through the softstart valve 21. This connection may be direct or via a port of the tapping duct 74 to the duct part, extending between the choke means 34 and the secondary duct 2, of the associated duct 3. Accordingly the current secondary pressure continuously obtains in the control chamber 73. This pressure exerts a switching over Fu opposing the force of the spring means 68.
The switch over valve 68 may control the fluid flow through a switching over duct 75 by way of which the pilot power duct 64b is joined with the second actuating chamber 63. In the initial position of the switch over valve member 67 the connection is interrupted. If the switch over valve member 67 shifted by a sufficient switch over force F0 into the switch over position illustrated in figure 4, the fluid passage through the switch over duct 75 is open.
A typical manner of operation of the valve means 6 is as follows.
Let it be assumed that the pilot valve 25 is deactivated and the principal valve member 33 is in the home position. Accordingly the secondary duct 2 and the distributor feed duct 12 connected with it is free of pressure, via the feed opening 23 pressure medium at a primary pressure is supplied, which is also present in the pilot feed duct 64a. The two

actuating chambers 62 and 63 are vented via the pilot valve 25. This home state is depicted in figure 2.
For switching on the valve means 6 the pilot valve 25 is operated by the supply of an electrical control signal. The pilot valve 25 opens the passage through the pilot duct 64 so that a fluid pilot signal, corresponding to the primary pressure, is fed to the first actuating chamber 62 to act on the actuating face 46. Owing to the resulting setting force the actuating element 48 is shifted until it abuts the second abutment face 54, it entraining the principal valve member 33 and overcoming the spring force of the return spring means 44. When the actuating element 48 reaches the second abutment face 54, the principal valve member 33 will be in the. softstart position depicted in figure 3.
The switch over valve member 67 in the initial position will then keep the second actuating chamber 64 separate from the pilot duct 64.
Starting with the switching over into the softstart position there comes a softstart phase lasting a certain time. It is characterized in that via the opened softstart duct 3 a choked flow of pressure medium will enter the secondary duct 2 so that the secondary pressure therein will gradually increase. The gradient of such pressure increase may be controlled by setting the choke means 38.
Via the tapping duct 74 the current secondary pressure will also obtain in the control chamber 73 of the switch over valve 26. with the increase in the secondary pressure the switching over force Fu will also increase, this having no effect as long as the threshold value set by the spring means 68 is not reached.
When this threshold value is reached the softstart phase will end. The switching over force Fu is now sufficient to shift the switch over valve member 62 into the switch over setting illustrated in figure 4, this meaning that the fluid pilot signal will, via the now opened switching over duct 75,

also take effect in the second actuating chamber 63 and therefore at the second actuating face 47. As a consequence of this the principal valve member 33 will be further shifted into the working position as illustrated in figure 4, the actuating element 48 then not moving any further. Since the cross section of the length portion 55 is smaller than that of the first actuating chamber 62, a differential force will act at the actuating element 4 8 holding same in engagement with the second abutment face 54.
Owing to the switching over into the working position the secondary duct 2 is supplied with pressure medium via the large cross section opened by the principal valve member 63 with the result that the secondary pressure promptly reaches the level of the primary pressure.
In the working embodiment the pressure obtaining in the secondary duct 2 is immediately switched to the switch over valve 26 as the control pressure providing the switching over force. Alternatively there is nevertheless the possibility of designing the switch over valve 26 to be electrically operated, the electrical switch over being generated with the cooperation of a pressure sensor or pressure sensor, which is responsive to the secondary pressure.
In order to return to the home position only the pilot valve 25 is to be turned off so that the pilot working duct 64b" is vented. The return spring means 44 then shifts the main valve member 33 back into the home position.
The spring means 68 is preferably made adjustable as regards its spring force. For this purpose a rotatable head 76 or some other suitable manual control may be present.
One advantage of the above described valve design lies in the lack of sensitivity as regards pressure fluctuations in the primary duct 1 or the secondary duct 2. Should owing to a pressure drop the switching over force Fu drop so far that the switch over valve 26 goes over into the initial position, this will be without effect on the working position of the main

valve member 13, seeing that the pilot fluid present in the
second actuating chamber 63 remains captive and can not
escape.
The valve means 6 may be operated both with a gaseous and also
with a liquid medium. Preferably compressed air comes into
question.

Claims
1. A valve means having a softstart function comprising: a softstart valve (21) having the following features:
- a principal valve (24) able to be switched over between
a home position, a softstart position and a working
position, said principal valve in the home position
separates a secondary duct (2) from a primary duct (1)
conducting pressure medium subject to a primary
pressure, said principal valve in the softstart position
connects the secondary duct (2) via a softstart duct (3)
containing a choke means (38), with the primary duct
(1), and said principal valve in the working position by bypassing the choke means (38) opens a connection between the secondary duct (2) and the primary duct (1),
- a pilot valve (25) provided for influencing the switching position of the principal valve (24), on whose operation a fluid pilot signal is generated acting on a first actuating face {46} of the principal valve (24) in order to switch over the principal valve (24) out of the home position and into the softstart position,
- and a switch over valve (26) able to be operated by the secondary pressure obtaining in the secondary duct (2), which valve at a predetermined level of the secondary pressure switches over the fluid pilot signal, produced by the pilot valve (25) to a second actuating face (47) of the principal valve (24) in order to switch over the principal valve (24) out of the softstart position into the working position.

2. The valve means in accordance with claim 1, characterized in that the secondary duct (2) is connected with a relief duct (4) in the home position of the principal valve (24) .
3. The valve means in accordance with claim 1 or with claim 2, characterized in that the choke means (38) are designed to be adjustable as regards choking intensity.
4. The valve means in accordance with any one of the claims 1 through 3, characterized in that the principal valve (24), the pilot valve (25) and the switch over valve (26) are combined together as a single subassembly.
5. The valve means in accordance with any one of the claims 1 through 4, characterized in that the pilot valve (25) is a solenoid valve.
6. The valve means in accordance with any one of the claims 1 through 5, characterized in that the two actuating faces {46 and 47) face in the same direction.
7. The valve means in accordance with any one of the claims 1 through 6, characterized in that the three switching positions of the principal valve (24) are set by corresponding switching positions of a movable principal valve member (33), the first and the second actuating face (46 and 47) being each designed to cooperate in a driving manner with the principal valve member (33).
8. The valve means in accordance with claim 7, characterized in that the first actuating face (46) is formed on an actuating element (48), formed separately from the principal valve member (33), such actuating element (48) on

being acted upon by the fluid pilot signal being able to be shifted as far as abutting on an engagement face (54) with a simultaneous entrainment of the principal valve member (33) wherein said engagement face is setting the softstart position, the principal valve member (33) being shifted away from the actuating element (48) when it is subsequently moved on further as far as the working position by the action of fluid on the second actuating face (47).
3. The valve means in accordance with claim 8, characterized in that the actuating element (48) is arranged axially following the linearly sliding principal valve member (33) and loosely engages the principal valve member (33) in a fashion only allowing transmittal of thrust forces.
10. The valve means in accordance with claim 8 or with claim 9, characterized in that the actuating element (48) is piston-like in configuration.
11. The valve means in accordance with any one of the claims 7 through 10, characterized in that the second actuating face (47) is arranged fixedly on the main valve member (33) .
12. The valve means in accordance with claim 11 in conjunction with any one of the claims 8 through 10, characterized in that the second actuating face (47) moves away from the first actuating face (46) when the principal valve (24) is switched over out of the softstart position into the working position.
13. The valve means in accordance with any one of the claims 7 through 12, characterized by a return spring means (44) biasing the principal valve member (33) into the home
position.

14. The valve means in accordance with claim 13, characterized in that the return spring means (44) is arranged coaxially on the principal valve member (33) axially between on the one hand the two actuating faces (46 and 47) and on the other hand the control portion (42) of the principal valve member (33) which is setting the switching positions.
15. The valve means in accordance with any one of the claims 7 through 14, characterized in that the first actuating face (46) delimits a first actuating chamber (62) which communicates with a pilot duct (64) supplying the fluid pilot signal and controlled by the pilot valve (25).
16. The valve means in accordance with any one of the claims 7 through 15, characterized in that the second actuating face (47) delimits a second actuating chamber (63), which communicates with a switch over duct (75) which communicates with a pilot duct {64} supplying the fluid pilot signal and is controlled by the pilot valve (25) and in which the switch over valve (26) is placed.
17. The valve means in accordance with a.ny one of the claims 1 through 16, characterized in that the switch over valve (26) comprises a switch over valve member (67) biased by a spring force toward a starting position and biased in the opposite direction by a switch over force which depends on the secondary pressure present in the secondary duct (2).
18. The valve means in accordance with claim 17, characterized in that the switch over valve member (67) governs the passage of fluid through a switch over duct (75), which on the one end is acted upon by the fluid pilot signal of the pilot valve and on the other end leads to the second actuating face (47) with the result that the passage of fluid

is prevented in the starting position of the switch over valve member (67) and is opened when the switch over valve member (67) is shifted into a switch over position owing to reaching a secondary pressure of a predetermined level.
19. The valve means in accordance with claim 17 or claim 18, characterized in that the spring force is provided by mechanical spring means (68), which more especially are able to be adjusted as regards their force.
20. The valve means in accordance with any one of the claims 1 through 19, characterized in that the secondary pressure obtaining in the secondary duct (2) is directly switched to the switch over valve (26) as a control pressure serving for producing the switch over force.
21. The valve means in accordance with any one of the claims 1 through 20, characterized by a fluid distributor (7) fitted with several control valves (8), which has a distributor feed duct (12) and at least one distributor relief duct (13 and 14}, which are respectively connected with the control valves (8) for fluid flow, the secondary duct (2) being connected with the distributor feed duct (12) and the primary duct (1) being connected with a distributor supply duct (22) opening at an outer face of the fluid distributor
(7) .
22. The valve means in accordance claim 21, characterized
in that the fluid distributor (7) possesses several component
mounting sites, from which respectively two distributor power
ducts (15 and 16) extend, which pass through the fluid
distributor (7), and said component mounting sites at least in
part being able to be selectively fitted with a control valve
(8) or with a softstart valve (21), wherein in the case of a
component mounting site being fitted with a softstart valve

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=KNfeLn6cYOwlvYJT4W8IUQ==&loc=egcICQiyoj82NGgGrC5ChA==

« Previous Patent

Next Patent »

Patent Number

271431

Indian Patent Application Number

1730/CHENP/2009

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

22-Feb-2016

Date of Filing

27-Mar-2009

Name of Patentee

FESTO AG & CO.KG

Applicant Address

RUITER STRASSE 82, 73734 ESSLINGEN,

Inventors:

#	Inventor's Name	Inventor's Address
1	BRENNER, JAKOB,	BAUMREUTE 34, D-73730 ESSLINGEN,
2	BOGDANOLWICZ, GRZEGORZ,	IN DEN STEINEN 17/5, 73760 OSTFIDERN,

PCT International Classification Number

F15B 11/068

PCT International Application Number

PCT/EP07/06832

PCT International Filing date

2007-08-02

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102006046450.8	2006-09-29	Germany