Title of Invention	A FUEL-INJECTION DEVICE FOR INTERNAL-COMBUSTION ENGINES
Abstract	A fuel-injection device for intemal-combustion engines, with a fuel high-pressure pump (1) which feeds fuel out of a low-pressure space (3) via a feed conduit (5) into a high-pressure collecting space (7) which is connected via high-pressure conduits (9) to the individual injection valves (11) projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an outward-opening injection-valve member (17), which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve (11), the injection valve member (17) being loaded constantly by the injection pressure in the opening direction counter to a closing force, characterized in that in the injection valve (11) a control pressure space (39, 33) is provided, which is contiguous with a pressure surface (43, 69, 85) arranged on the injection valve member (17) and is supplied with pressure medium from the high-pressure collecting space via a high pressure conduit (47) and the pressure of which is capable of being adjusted in a controlled manner, so as to vary the closing force on the injection valve member by means of at least one control valve (49, 55, 79) which is inserted into the high-pressure conduit and/or into a relief conduit (53, 73) and which is controlled by the control means.

Title of Invention

A FUEL-INJECTION DEVICE FOR INTERNAL-COMBUSTION ENGINES

Abstract

A fuel-injection device for intemal-combustion engines, with a fuel high-pressure pump (1) which feeds fuel out of a low-pressure space (3) via a feed conduit (5) into a high-pressure collecting space (7) which is connected via high-pressure conduits (9) to the individual injection valves (11) projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an outward-opening injection-valve member (17), which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve (11), the injection valve member (17) being loaded constantly by the injection pressure in the opening direction counter to a closing force, characterized in that in the injection valve (11) a control pressure space (39, 33) is provided, which is contiguous with a pressure surface (43, 69, 85) arranged on the injection valve member (17) and is supplied with pressure medium from the high-pressure collecting space via a high pressure conduit (47) and the pressure of which is capable of being adjusted in a controlled manner, so as to vary the closing force on the injection valve member by means of at least one control valve (49, 55, 79) which is inserted into the high-pressure conduit and/or into a relief conduit (53, 73) and which is controlled by the control means.

Full Text	The invention relates to a fuel-injection device for internal-combustion engines according to the pre-characterizing clause of Patent Claim 1. In a fuel-injection device of this type known from the specialist periodical ATZ/MTZ, special issue on 'Motor und Umwelt' [Engines and the Environment] 1992, pages 28 to 30, a high-pressure pump feeds fuel out of a low-pressure space into a high-pressure collecting space (common-rail) and builds up there a fuel high-pressure level which is available for injection irrespective of the engine speed. High-pressure conduits corresponding to the number of injection points lead off from the high-pressure collect¬ing space to the individual injection valves projecting into the combustion space of the internal-combustion engine to be supplied, the high-pressure conduits opening onto this pressure space which loads the valve member in the opening direction. In this case, the control of the opening-stroke movement of the valve members of the injection valves designed as "inward-opening injection nozzles" takes place by means of a 3/2-way valve inserted into a part conduit which branches off from the high-pressure conduit and which opens into a control space loading the valve member in the closing direction. At the same time, that pressure application surface on the valve member of the injection valve which acts in the closing direction is larger than the pressure surface acting in the opening direction, so that, when the control space is loaded with high pressure, the valve member is kept pressed onto its valve seat. When inj ection is to take place, the 3/2-way valve connects the control space to a fuel tank, so that the pressure In the control space expands into the tank and the opening force applied to the valve member is then sufficient to lift off the valve member from the seat, so that fuel can be injected via the injection orifices. To close the injection valve, the control space is connected once again to the high-pressure conduit. At the same time, to shape the injec¬tion flow, a throttle is inserted into the connecting conduit between the 3/2-way valve and control spacie, and for a rapid closing of the valve member at the end of injection a non-return valve opening in the direction of the control space is used. In this case, however, the known fuel-injection device has the disadvantage that it is not possible to have variable injection cross-sections by means of the injec¬tion valves used. This leads, particularly at a low engine speed and load, as a result of the very high injection pressure in the high-pressure collecting space, to very short injection times which have an adverse effect on the fuel treatment in the combustion space and consequently on the quality of combustion. Moreover, the use of a complicated 3/2-way valve for controlling the injection operation is very expensive, so that the production of the known fuel-injection device involves a high outlay and is cost-intensive. Advantages of the invention In contrast to this, the advantage of the fuel• injection device according to the invention for internal-combustion engines, having the characterizing features of Patent Claim 1, is that the known common-rail injection system can be improved to the effect that the advantages of the constantly available high injection pressure can be utilized logically by means of a variable injection cross-section on the injection valve. This is made possible in an advantageous way by the use of an injec¬tion valve having an outward-opening valve member, via the adjustable opening stroke of which a variable injection cross-section can be controlled. The injection valve of the outward-opening type can, in this case, be controllable continuously, for which purpose an annular gap openable in dependence on. the valve-member stroke and located between the closing head and the valve seat forms the injection cross-section. Preferably, the injection cross-section is to be con¬trolled by means of a slide valve which precedes the sealing cross-section and which, in its valve member, has, for example, a plurality of geometrically exactly defined injection orifices, via the arrangement of which injection cross-sections can be set precisely in depend¬ence on the opening stroke during their emergence from overlap with the housing. In this case, these injection orifices are preferably formed by two injection-hole rows which are located axially one above the other and which are opened in succession during the opening stroke of the valve member. It is thereby possible in a constructively simple way, by means of a specific valve-member stroke, to open only the lower injection-hole row located near the combustion space and thus, for example, initially open only half the injection cross-section. At the same time, control possibilities are provided on the valve member, allowing the valve member to wait in this specific Intermediate position. Alternatively, however, it is also possible to provide even more injection-hole rows and specific waiting positions of the valve member. In this case, the said injection holes have the advantage over the annular gap that the jet direction and the jet shape of the fuel to be injected can be set more effectively. The described opening of only a reduced Injection cross-section, preferadsly 50%, has the advantage, particularly at low engine speeds and in the part-load range of the internal-combustion engine to be supplied, that, despite a high injection pressure, the Injection time can be set at the optimum value for favourable fuel treatment. Thus, on the fuel-injection device according to the Invention, the fuel injection can be adapted to the optimum to the respective operating points of the internal-ccinbustion engine by the combination of a variable injection pressure and variable injection cross-section, along with a freely selectable moment of injection. In this case, the variation in the injection pressure takes place in a knovm way by a pressure regula¬tion of the high-pressure collecting space. A further advantage is achieved by the use of a simple 2/2-way valve for controlling the injection operation on the injection valve, the said 2/2-way valve at the same time preferably being actuated by an electromagnet. Alternatively to thie, however, mechanical, hydraulic or pneumatic actuations or the 3/2-way valves known from the prior art are also possible. In this case, the closing force applied to the valve member of the Injection valve can be formed by a spring force or the high pressure in the injection system, the most diverse control concepts on the 2/2-way valve being possible for this purpose. Thus, for example, the solenoid valve can keep the 2/2-way valve currentlessly open or closed, so that, in the closed state of the injection valve, a return space receiving the end of the valve member located on the combustion-space side is pressureless or pressure-loaded. The intermediate stop keeping the valve member in a specific position opening only the lower injection-hole row can advantageously be designed as a hydraulic stop (closed bore) or as a □lechanical stop {activation of a second spring) . When the system pressure is used as a closing force, it is par¬ticularly advantageous to have on the valve member a tiydraulically adjustable closing piston, via the hydraulically adjustable axial extent of which a continu¬ously adjustable stroke distance of the valve member Is possible. At the same time, the fuel high pressure in the injection system or the position of the 2/2-way valve can De used as a control variable for the opening-stroke novement of the valve member. In the event, the various control concepts have different advantages in dependence on the preconditions on the interaal-combustion engine to be supplied, which is why only four design possibilities are explained although their features are interchangeable and can be combined with one another. Accordingly, the present invention provides a fuel-injection device for internal-combustion engines, with a fuel high-pressure pump which feeds fuel out of a low-pressure space via a feed conduit into a high-pressure collecting space which is connected via hi^-pressure conduits to the individual injection valves projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an oirtward-opening injection-valve member, which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve, the injection valve member being loaded constantly by the injection pressure in the opening direction counter to a closing force, ::iiaracterized in that in the injection valve a control pressure space is provided, which s contiguous with a pressure surface arranged on the injection valve member and is lupplied with pressure medium from the high-pressure collecting space via a high iressure conduit and the pressure of which is capable of being adjusted in a controlled maimer, so as to vary th& closing force on the injection valve member by means of at ;ast one control valve which is inserted into tlie high-pressure conduit and/or into a ;lief conduit and which is controlled by the control means . Further advantages and advantageous embodiments of the subject of the ivention can be taken from the description, with reference to the accompanying awin^ and the Patent claims. Four exemplary embodiments of the fuel-injection device according to the invention for internal-combustion engines are represented in the drawing and are explained in more detail below- Figure 1 shows a first exemplary embodiment with a hydraulic closing force on the valve member of the injection valve and with a currentlessly open 2/2-way solenoid valve. Figure 2 shows an enlarged sectional representation of the injection valve from Figure 1 in the region of the injection orifices. Figure 3 shows a second exemplary embodiment with a hydraulic closing force on the valve member, with a currentlessly closed 2/2-way valve and with a hydraulically adjustable closing piston, Figure 4 shows a third exemplary embodiment, in which the closing force is applied by a closing spring, with a 2/2-way solenoid valve currentlessly open, and Figure 5 shows a fourth exemplary embodiment, in which the 2/2-way solenoid valve is currentlessly closed and the closing force is generated by a 2-spring arrangement. Description of the exemplary embodiments The first exemplary embodiment of the fuel-injection device for internal-combustion engines, which is represented diagrammatically in Figure 1, has a fuel high-pressure pump 1 which feeds fuel out of a low-pressure space 3, preferably the fuel tank, via a feed conduit 5 into a high-pressure collecting space 7. High-pressure conduits 9 corresponding to the number of injection points lead off from this high-pressure collecting space 7 to the individual injection valves 11 projecting into the combustion space of the internal- combustion engine to be supplied. The injection valves 11 lave a valve body 13, with a central bore 15, in which is juided axially a piston-shaped valve member 17 having, at Lts end located on the combustion-space aide, a closing lead 19 proj ecting out of the bore 15 and forming a ralve-closing member. At the same time, the closing head .9, shown enlarged in Figure 2, has, on its side facing :he valve body 13, a sealing face 21 which forms a lealing edge and by means of which it cooperates with a -alve-seat face 23 arranged on that end face of the valve ody 13 located on the combustion-space side. The closing ead 19 projects with a cross-section enlarged relative o the piston shank of the valve member 17 Into a part of idened diameter of the bore 15 and thus limits, with its nd face 25 facing away from the combustion space, a ressure space 27 which Is formed In the bore and which xtends via an annular gap 29 between the wall of the ore 15 and the valve-member shank as far as a fuel ciflow duct 32 in the valve body 13. In this case, the alarged cross-section on the closing head 19 is prefer- sly formed by a sleeve 26 which Is fastened to the Losing head 19 and which sealingly slides axially on the ill of the bora 15. Provided in this sleeve 26 forming movable valve slide are preferably two rows, located dally one above the other, of injection orifices Lnjection-hole rows) 28 which are arranged In such a way lat, during the emergence of the valve member 17 from be bore 15, a first lower row located near the combus- Lon space is opened first after a specific idle stroke, illst the second upper row comes out of overlap with the are wall of the valve body 13 only during the further live-member stroke. Moreover, recesses 30 between the lve member 17 and sleeve 25 are provided for supplying lel from the annular gap 29 to the injection orifices I. be annular gap 29 is limited, in the direction facing may from the closing head 19, by a housing web 31, in wich the diameter of the bore 15 decreases in such a way cnac cue valve member 17 is sealingly guided allde-diaplaceably. This housing web 31 has adjoining it in the direction facing away from the combustion space a back¬space 3 3 which is formed by a renewed increase in diameter of the bore 15 and into which that end of the valve member 17 facing away from the combustion space projects and which is closed by means of a housing cover 35. At the same time, the valve member has^ at its end facing away from the combustion space, a. closing piston 37 which forms an actuating part and which slides seal¬ingly on the wall of the backspace 33 and thus divides the latter into a lower part space located on the combustion-space side and forming a return space 39 and an upper part space facing away from the combustion space and forming a relief space 41, the lower annular end face of the closing piston 37 located on the combustion-space side forming a pressure application surface 43 of the valve member 17 in the closing direction, the said pressure application surface being larger than the end face 25 acting in the opening direction and located on the closing head 19. To supply fuel to the injection valve 11 and to control the opening-stroke movement of the outward-opening valve member 17, the high-pressure conduit 9 branches, near the injection valve 11, into two part conduits, of which a first part conduit 45 opens in an unthrottled manner into the fuel inflow duct 32 and further into the pressure space 27 and a second part conduit 47 opens into the return space 39 of the backspace 33, the second part conduit 47 being closable by means of a 2/2-way valve 49 inserted therein and controllable by means of an electromagnet. To relieve the upper relief space 41 of the backspace 33 of pressure, a relief conduit 51 leads off from the latter into the low-pressure space 3. To control the opening-stroke movement, a spill conduit 53 leads off from the lower return space 39 and opens into the backspace 33 in such a way that it cannot be closed by the closing piston 37 during its stroke movement/ and into which is inaerted a control solenoid valve 55 which is designed as a 2/2-way valve and which opens the spill conduit 53 into the low-pressure space 3 or closes it and can, at the same time, be used for a plurality of injection valves. Furthermore, a throttle conduit 59 containing a res¬triction 57 leads off from the return space 39 into the low-pressure space 3, the mouth of the said throttle conduit being arranged in the return space 39 in such a way that, after a specific opening-stroke distance has been covered, it can be closed by the closing piston 37, this opening-stroke position of the valve member 17 then corresponding to the opening of the lower injection-hole row. To limit the maximnjm opening-stroke distance of the valve member 17, a stop sleeve 61 is inserted into the return space 39, the upper annular face of which stop sleeve forms a stop cooperating with the pressure surface 43 of the closing piston 37, the said stop sleeve having passage orifices for the second part conduit 47 and for the spill conduit 53. The first exemplary embodiment represented in Figures 1 and 2 works as follows. In the closed state of the injection valve 11, the 2/2-way valve 49 is open (electromagnet currentless), so that the fuel high pressure built up by the high-pressure pump 1 in the high-pressure collecting space 7 continues into the return space 39 of the backspace 33. The high pres¬sure applied to the pressure surface 43 of the closing piston 37 keeps the valve member 17 pressed with its sealing face 21 onto the valve-seat face 23. To open the injection valve 11, the 2/2-way valve 49 (live) breaks the connection between the backspace 33 and the high-pressure collecting space 7. The high pressure in the lower return space 39 is reduced via the throttle conduit 59, this operation and therefore the opening-stroke trend of the valve member 17 being capable of being set via the throttle 57. With the reduction of the closing force acting on the valve member 17, the opening pressure prevailing in the pressure space 27 and acting on the valve member 17 via the face 25 is now sufficient to lift off the valve member 17 from the valve seat 23 and to expose the injection orifices 28. At the same time, the valve member 17 is initially displaced only until the closing piston 37 closes the throttle conduit 59 and the now closed lower return space 39 forms a hydraulic stop, in this position the lower injection-hole row being opened. If the opening stroke of the valve member 17 is to be continued, the control valve 55 opens the spill conduit 53 and the pressure in the lower return apace 3 9 is expanded into the low-pressure space 3, so that the valve member 17 can cover i ts maximum opening distance, until the closing piston 37 comes to bear on the stop sleeve 61, and at the same time also opens the second upper injection-hole row of the injection, orifices 28. If the valve member 17 is to be prevented from waiting in the intermediate position, it is possible, by an immediate opening of the spill conduit 53, to execute a rapid maximum opening stroke. For a renewed closing of the injection valve 11, the 2/2-way valve is opened again, so that, with the spill conduit 53 now closed, the fuel high pressure builds up once again in the lower return space 39 and displaces the valve member 17 back onto its valve seat 23. The second exemplary embodiment represented in Figure 3 differs from the first only in the type of control of the opening-stroke movement of the valve member, which is why this description deals only with these components, identical components being designated in a similar way to the first exemplary embodiment. In this case, a restriction 63 is inserted into the second part conduit 47 branching off from the high-pressure conduit 9 and opening into the lower return space 39. Moreover, a control conduit 65 leads off from :he return space 39, the said control conduit opening Lnto the low-pressure space 3 and being closable by means of the electromagnetically controlled 2/2-way valve 49 now inserted therei In Figure 3, the closing piston 37 is of two-part design, an upper piston part 67 which faces away from the combus¬tion space being fixedly connected to that end of the valve member 17 projecting into the backspace 33, and a lower piston part 69 which faces the combustion space being guided axially diaplaceably on the valve-member shank. The space enclosed between the piston parts 67, 69 forma a setting space 71 which can be filled with fuel via a fuel conduit 73 fed from the low-pressure space 3 and having a non-return valve 75 opening in the direction of the setting space 71 and which can be relieved into bhe low-pressure space 3 via a part conduit 77 which pranches off from the fuel conduit 73 and which can be opened by means of a control valve 79. A compression spring 61 clamped between the piston parts 57, 69 displaces the piston parts 67, 69 into their unitlal position when the backspace 33 is relieved, the second exemplary embodiment represented in Figure 3 borks as follows. with the injection valve 11 closed, the 2/2-way valve 49 nserted into the control conduit 65 is closed {current-ess} , so that the fuel high pressure builds up in the eturn space 39 via the second part conduit 47 and loads he lower piston part 69 in the closing direction of the alve member 17. At the same time, depending on the illing of the setting space 71, this closing force is ransmitted directly or via a hydraulic cushion to the pper piston part 67 fixed to the valve member, so that he valve member 17 is held against the valve seat 23. or opening the injection valve 11, the 2/2-waY valve 49 live) opens, so that the pressure in the return space 3 9 xpands into the low-pressure space 3. As a result of tiis, the pressure in the pressure space 27 acting on the alve member 17 in the opening direction is sufficient to ift off the valve member 17 from its seat 23, this pening-stroke movement continuing until the lower piston art 69 comes to bear on the stop sleeve 61. A variable broke control of the valve member, particularly a iiting of the valve member 17 in the position in which only the lower injection-hole row ia opened, is achieved by means of a specific filling of the setting space 71, for which purpose this hydraulic volume is filled up completely via the fuel conduit 73 for a minimum stroke and is correspondingly emptied via the control valve 79 for a maximum stroke, intermediate positions also being possible as result of a suitable filling of the setting space 71. The closing of the injection valve 11 takes place by means of a renewed closing of the 2/2-way valve 49, with the result that the closing pressure builds up again in the return space 39 of the backspace 33 and the valve member 17 is moved back onto its valve seat 23. The third exemplary embodiment represented in Figure 4 differs from the preceding exemplary embodiments in the type of closing force which is applied to the valve member 17 and which is generated here by means of a spring force. For this purpose, there is arranged in the backspace 33 a valve spring 83 which is clamped between a spring plate 85 located at that end of the valve member 17 facing away from the combustion space and an annular shoulder 87 limiting the backspace 33 on the combustion-space side and which keeps the valve member 17 in bearing contact on the valve seat 23 counter to the fuel high pressure prevailing in the pressure space 27 and loading the valve member 17 in the opening direction. In this case, a relief conduit 51 leads off from the backspace 33, the said relief conduit opening into the low-pressure space 3 and being closable via the 2/2-way valve 49 inserted therein. Moreover, between the backspace 33 and 2/2-way iralve 49, the second part conduit 47 forming a connecting =onduit between the high-pressure conduit 9 and the sackspace 33 opens into the relief conduit 51, a restric- ;ion 57 being inserted in the second part conduit 47 in -.he third exemplary embodiment of the fuel-injection levice according to the invention. :he third exemplary embodiment represented in Figure 4 rorks as follows. With the injection valve 11 in the closed state, the 2/2-way valve 49 arranged in the relief conduit 51 or in the second part conduit 47 is open (currentless) , so that no fuel high pressure can build up in the backspace 33 and the valve spring 83 keeps the valve member 17 on the valve seat 23 coimter to the fuel high pressure prevail¬ing in the pressure space 27 and acting on the valve member 17 in the opening direction. For opening the injection valve 11/ the 2/2-way valve 49 closes the pressure-relieving connection, between the backspace 33 and low-pressure space 3, so that the fuel high pressure of the injection system builds up in the backspace 33 via the second part conduit 47. At the same time, the result¬ant pressure force in the opening direction of the valve member 17, which is now applied to the valve-member part projecting into the backspace 33, in conjunction with the pressure force prevailing in the pressure space 27, is higher than the return force of the valve spring 83, so that the valve member 17 is lifted off from the valve seat 23 and exposee the injection orifices. A waiting of the valve member 17 in a position, in which only the lower injecticn-bole row is initially opened, can be achieved, for example, via a progressive characteristic of the valve spring 83 or a specific idle stroke, the fuel high pressure of the high-pressure collecting space being used as a control pressure. For closing the injection valve at the end of the injec¬tion operation, the 2/2-way valve 49 once again opens the relief conduit 51 into the low-pressure space 3, so that the fuel high pressure in the backspace 33 expands rapidly and the valve spring 83 moves the valve member 17 back onto the valve seat 23. In the fourth exemplary embodiment represented in Figure 5, the second part conduit 47 starting from the ligh-pressure conduit 9 opens directly into the backspace 33, the second part conduit 47 being cloeable by means of -he 2/2-way valve inserted therein. The pressure relief 3f the backspace 33 takes place by means of the relief ;onduit 51 which leads off from the latter into the low-pressure space 3 and which, in the fourth exemplary embodiment, has a restriction 57. The closing or return force on the valve member 17 is generated via a 2-spring arrangement, for which purpose an annular step 89 is provided on the shank part of the valve member, the said shank part projecting into the backspace 33, between the spring plate 85 arranged at the end located on the combustion-space side and the annular shoulder 87 limiting the backspace 33. In this case, a first valve spring 91 is clamped between the spring plate 85 and the annular step 89 and a second valve spring 93 is clamped between the annular step 89 and the annular shoulder S"? fixed to the housing, the spring rigidity of the first valve spring 91 being lower than that of the second valve spring 93. For setting the pre-stroke movement of the valve member 17 executed counter to the force of the first valve spring 91, in the exemplary embodiment described there is fastened to the spring-side annular end face of the spring plate 85 a sleeve 95, of which the end face facing away from the spring plate 85 bears on the annular step 89 after the execution of a pre-stroke movement and which then, cutting out the first valve spring 91, makes a rigid connection between the spring plate 85 and annular step 89, so that, during the further opening stroke, only the second valve spring 93 takes effect. This waiting in an intermediate position 3an alternatively also be achieved without a sleeve 95, Ln which case both valve springs are effective during the remaining s troke■ The fourth exemplary embodiment represented in Figure 5 torka as follows- iith the injection valve 11 closed, the 2/2-way valve 49 .nserted into the conduit 47 is closed (currentlees), so :hat the backspace 33 is relieved to a specific pressure -^ia the relief conduit 51 containing a specific throttle 17. In this case/ the valve member 17 is kept in bearing lontact on the valve seat 23 coxinter to the pressure in he pressure space 27 by the force of the valve springs 1, 93. If injection is to take place, the 2/2-way valve opens, so that the fuel high pressure of the inj ection system builds up in the backspace 33 and, as described with regard to Figure 4, moves the valve member 17 in the opening direction. A pre-stroke until the sleeve 95 comes to bear on the annular step 89 ia first executed counter to the lower spring force of the first valve spring 91, the said pre-stroke being sufficient to open the lower injection-hole row on the valve member 17. The valve member 17 can be kept in this position by the timed activation of the 2/2-way valve 49 in order to maintain a constant pressure in the backspace 33. If the total injection cross-section on the valve member 17 is to be opened, the supply of pressure into the backspace 33 is not interrupted, so that the fuel pressure in the back¬space 33 rises in such a way that the valve member 17 is displaced further, counter to the force of the second valve spring 17, into a position in which the second upper injection-hole row is also opened. for the subsequent closing of the injection valve 11, the 2/2-way valve 49 is closed once again, so that the high pressure in the backspace 33 is expanded into the low-pressure space 3 via the relief conduit 51 and the valve springs 91, 93 move the valve member 17 back onto its leat 23. :n all the alternative versions, the actuation of the 2/2-way control valves 49 takes place by means of an lectromagnet which is activated by an electronic control nit (not shown), the control unit processing in a known may a multiplicity of operating parameters of the nternal-combustion engine to be supplied. It ia thus possible in a constructively simple ay to combine the advantages of a "common-rail" injec-ion system with the advantages of an injection valve of he outward-opening type, so that, in addition to a reely selectEQile variable start of injection and end o£ njection and, a variable injection pressure, a variable ejection cross-section can also be set freely over the itire characteristic map of the internal-combustion igine to be supplied, this fuel-injection device being controllable in a simple way by means of a 2/2-way valve. WE CLAIM: 1. A fuel-injection device for intemal-combustion engines, with a fuel high-pressure pump (1) which feeds fuel out of a low-pressure space (3) via a feed conduit (5) into a high-pressure collecting space (7) which is connected via high-pressure conduits (9) to the individual injection valves (11) projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an outward-opening injection-valve member (17), which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve (11), the injection valve member (17) being loaded constantly by the injection pressure in the opening direction counter to a closing force, characterized in that in the injection valve (11) a control pressure space (39, 33) is provided, which is contiguous with a pressure surface (43, 69, 85) arranged on the injection valve member (17) and is supplied with pressure medium from the high-pressure collecting space via a high pressure conduit (47) and the pressure of which is capable of being adjusted in a controlled manner, so as to vary the closing force on the injection valve member by means of at least one control valve (49, 55, 79) which is inserted into the high-pressure conduit and/or into a relief conduit (53, 73) and which is controlled by the control means. 2. The fuel-injection device according to claim 1, wherein the valve member (17) has a valve shank which is guided through a bore (15) of a valve body (13) of the injection valve (11) and which has, at its end located on the combustion-space side, a closing head (19) which projects out of the bore (15) and forms a valve-closing member and which, on its side facing the valve body (13), has a sealing face (21) which forms a sealing edge and by means of which it cooperates with a valve-seat face (23) arranged on that end face of the valve body (13) located on the combustion- space side, and with a pressure space (27) which is connected to the high-pressure conduit_ (9) and is arranged between the shank of the valve member (17) and the wall of the bore (15) and which is limited towards the combustion space by the closing head (19), there being arranged on the valve member (17) an axially pointing pressure surface (25) limited between the valve seat (23) and the valve shank. 3. The fuel-injection device according to claim 2, wherein the injection cross-section on the injection valve (11) is controlled by a slide-valve arrangement, the movable slide part of which is adjusted together with the valve member (17) and the orifice cross-section of which, forming the injection cross-section, is located upstream of the valve seat (23). 4. The fuel-injection device according to claim 3, wherein the injection cross-section is opened only after the execution of a specific stroke of the valve member (17) in the opening direction. -■* 5. The fuel-injection device according to claim 3, wherein part of the valve member (17) is designed as the movable slide part which is guided in the bore (15) in the region of the closing head (19) and which has two rows, located axiaily one above the other, of injection orifices (28) which are distributed over its circumference and which, starting from the pressure space (27), are arranged in such a way that, during the opening-stroke movement of the valve member (17), the outlet orifices of the injection orifices (28) offset axiaily relative to one another can be opened towards the combustion space in succession as a result of emergence from overlap with the bore (15) at the control edge formed by the valve-seat face (23). 6. The fuei-injection device according to claim 2, wherein the valve member (17) is connected, at its end facing away from the combustion space, to an actuating part which limits, in the valve body (13), a backspace (33) connectable to the high-pressure conduit (9), the opening movement and/or closing movement of the valve member (17) being controllable by the control valve at least in operative connection via the high-pressure filling or high-pressure relief of the said backspace. 7. The fuel-injection device according to claim 1, wherein the control valve controlling the opening and closing movement of the injection valve (11) and located in the high-pressure conduit is designed as an electrically controlled directional valve (49). 8- The fuel-injection device according to claim 1, wherein the electrically controlled directional valve (49) is a solenoid valve. 9. The fuel-injection device according to claim 6, wherein the injection valve (11) is connected to the high-pressure collecting space (7) via two part conduits, of which a first part conduit (45) constantly connects the pressure space (27), formed between the valve member (17) and bore (15) and acting on the valve member (17) in the opening direction, to the high- pressure collecting space (7) and a second part conduit (47) opens into a return space (39) separated from the pressure space (27), the filling of this return space (39) with fuel which is under high pressure being controllable by means of the control valve designed as an electrically controlled directional valve (49). 10. The fuel-injection device according to claim 9, wherein the actuating part of the valve member (17) has a closing piston (37), of which the end face located on the combustion-space side has a pressure application surface (43), via which the valve member (17), can be loaded in the closing direction and which is larger than the pressure surface (25) acting in the opening direction and located on the valve member (17), the closing piston (37) sliding sealingly on the wall of the backspace (33) and thus dividing the latter, in the valve body (13), into an upper relieved relief space (39, 41) facing away from the combustion space and the lower return space (39) facing the combustion space. 11. The fuel-injection device according to claim 10, wherein the electrically controlled directional valve (49) is inserted into the second part conduit (47) of the high-pressure conduit (9). 12. The iuel-injection device according to claim 11, the directional valve (49) is designed as a 2/2-way valve, and the return space (39) is constantly connected to the low-pressure space (3) via a throttle conduit (59) containing a throttle (57). 13. The fuel-injection device according to claim 10, wherein a spill conduit (53) which cannot be closed by the closing piston (37) during its stroke movement leads off from the return space (39) into the low-pressure space (3) and can be opened and closed by means of an electrically controlled valve (55), 14. The fuel-injection device according to claim 12, wherein the throttle conduit (59) from the return space (39) into the low-pressure space (3) is closed by the closing piston (37) after an opening-stroke distance of the valve member (17), opening the lower row of injection orifices (28) on the combustion-space side has been covered. 15. The fuel-injection device according to claim 10, wherein there is provided in the return space (39) a stroke stop (61), onto which the closing piston (37) comes to bear with its pressure application surface (43) after the execution of a maximum opening-stroke movement. 16. The fuel-injection device according to claim 10, wherein a restriction (63) is arranged in the second part conduit (47) to the high-pressure conduit (9), and in that spill conduit (65) leads off from the return space (39) into the low- pressure space (3) where a directional valve (49) is arranged in the spill conduit (65), said spill conduit (65) can be closed by the directional valve (49) controlling the opening and closing movement of the valve member (17). 17. The fuel-injection device accordmg to claim 15, wherein the axial length of the closing piston (37) in the direction of the lower return space (39) can be varied. 18. The fuel-injection device according to claim 17, wherein the closing piston (37) is formed from two piston parts, of which an upper piston part (67) facing away from the combustion space is fixedly connected to the valve member (17) and a lower piston part (69) facing the combustion space is guided axially displaceably on the shank of the valve member (17), there being enclosed between the piston parts (67, 69) a setting space (71), from which a fuel conduit (73) operable by an electrically controlled valve (79) leads off into the low-pressure space (3), and with a compression spring (81) clamped between the piston parts (67,69) and located in the setting space (71). 19. The fuel-injection device according to claim 9, wherein the shank of the valve member (17) is sealingly guided in a part of the bore (15) which limits the backspace (33), and in that the valve member (17) has, at its end facing away from the combustion space and penetrating into the backspace (33), a spring plate (85), between which and an annular shoulder (87) formed at the transition of the bore (15) into the backspace (33) is clamped a valve spring (83) which loads the valve member (17) in the closing direction. ^ 20. The foel-injection device according to claim 19, wherein a restriction (57) is provided in the second part conduit (47), and in that a relief conduit (51) into the low-pressure space (3) branches off from the second part conduit (47), from the backspace (33), into which relief conduit (51) is inserted an electrically controlled directional valve (49) controlling the opening movement of the valve member (17). 21. The fuel-injection device according to claim 9, wherein the valve member (17) has, at its end facing away from the combustion space, a spring plate (85), between which and that wall of the backspace (33) formed by an annular shoulder (87) of the bore (15) in the valve body (13) is clamped a valve-spring arrangement which is formed from two springs (91, 93) and which load the valve member (17) in the closing direction and take effect in succession during the opening-stroke movement of the valve member (17). 22. The fuel-injection device according to claim 19 or 21, wherein the directional valve (49) controlling the opening movement of the injection valve (11) is inserted into the second part conduit (47) opening into the backspace (33), and in that a relief conduit (51) into the low-pressure space (3), the said relief conduit containing a restriction (57), leads off from the backspace (33). 23. A fuel-injection device for internal-combustion engines substantially as herein described with reference to the accompanying drawings.

Full Text

The invention relates to a fuel-injection device for internal-combustion engines according to the pre-characterizing clause of Patent Claim 1. In a fuel-injection device of this type known from the specialist periodical ATZ/MTZ, special issue on 'Motor und Umwelt' [Engines and the Environment] 1992, pages 28 to 30, a high-pressure pump feeds fuel out of a low-pressure space into a high-pressure collecting space (common-rail) and builds up there a fuel high-pressure level which is available for injection irrespective of the engine speed. High-pressure conduits corresponding to the number of injection points lead off from the high-pressure collect¬ing space to the individual injection valves projecting into the combustion space of the internal-combustion engine to be supplied, the high-pressure conduits opening onto this pressure space which loads the valve member in the opening direction. In this case, the control of the opening-stroke movement of the valve members of the injection valves designed as "inward-opening injection nozzles" takes place by means of a 3/2-way valve inserted into a part conduit which branches off from the high-pressure conduit and which opens into a control space loading the valve member in the closing direction. At the same time, that pressure application surface on the valve member of the injection valve which acts in the closing direction is larger than the pressure surface acting in the opening direction, so that, when the control space is loaded with high pressure, the valve member is kept pressed onto its valve seat. When inj ection is to take place, the 3/2-way valve connects the control space to a

fuel tank, so that the pressure In the control space expands into the tank and the opening force applied to the valve member is then sufficient to lift off the valve member from the seat, so that fuel can be injected via the injection orifices. To close the injection valve, the control space is connected once again to the high-pressure conduit. At the same time, to shape the injec¬tion flow, a throttle is inserted into the connecting conduit between the 3/2-way valve and control spacie, and for a rapid closing of the valve member at the end of injection a non-return valve opening in the direction of the control space is used.
In this case, however, the known fuel-injection device has the disadvantage that it is not possible to have variable injection cross-sections by means of the injec¬tion valves used.
This leads, particularly at a low engine speed and load, as a result of the very high injection pressure in the high-pressure collecting space, to very short injection times which have an adverse effect on the fuel treatment in the combustion space and consequently on the quality of combustion.
Moreover, the use of a complicated 3/2-way valve for controlling the injection operation is very expensive, so that the production of the known fuel-injection device involves a high outlay and is cost-intensive.
Advantages of the invention
In contrast to this, the advantage of the fuel• injection device according to the invention for internal-combustion engines, having the characterizing features of Patent Claim 1, is that the known common-rail injection system can be improved to the effect that the advantages of the constantly available high injection pressure can be utilized logically by means of a variable injection cross-section on the injection valve. This is made possible in an advantageous way by the use of an injec¬tion valve having an outward-opening valve member, via the adjustable opening stroke of which a variable

injection cross-section can be controlled. The injection valve of the outward-opening type can, in this case, be controllable continuously, for which purpose an annular gap openable in dependence on. the valve-member stroke and located between the closing head and the valve seat forms the injection cross-section. Preferably, the injection cross-section is to be con¬trolled by means of a slide valve which precedes the sealing cross-section and which, in its valve member, has, for example, a plurality of geometrically exactly defined injection orifices, via the arrangement of which injection cross-sections can be set precisely in depend¬ence on the opening stroke during their emergence from overlap with the housing. In this case, these injection orifices are preferably formed by two injection-hole rows which are located axially one above the other and which are opened in succession during the opening stroke of the valve member. It is thereby possible in a constructively simple way, by means of a specific valve-member stroke, to open only the lower injection-hole row located near the combustion space and thus, for example, initially open only half the injection cross-section. At the same time, control possibilities are provided on the valve member, allowing the valve member to wait in this specific Intermediate position. Alternatively, however, it is also possible to provide even more injection-hole rows and specific waiting positions of the valve member. In this case, the said injection holes have the advantage over the annular gap that the jet direction and the jet shape of the fuel to be injected can be set more effectively.
The described opening of only a reduced Injection cross-section, preferadsly 50%, has the advantage, particularly at low engine speeds and in the part-load range of the internal-combustion engine to be supplied, that, despite a high injection pressure, the Injection time can be set at the optimum value for favourable fuel treatment. Thus, on the fuel-injection device according to the Invention, the fuel injection can be adapted to the

optimum to the respective operating points of the internal-ccinbustion engine by the combination of a variable injection pressure and variable injection cross-section, along with a freely selectable moment of injection. In this case, the variation in the injection pressure takes place in a knovm way by a pressure regula¬tion of the high-pressure collecting space. A further advantage is achieved by the use of a simple 2/2-way valve for controlling the injection operation on the injection valve, the said 2/2-way valve at the same time preferably being actuated by an electromagnet. Alternatively to thie, however, mechanical, hydraulic or pneumatic actuations or the 3/2-way valves known from the prior art are also possible.
In this case, the closing force applied to the valve member of the Injection valve can be formed by a spring force or the high pressure in the injection system, the most diverse control concepts on the 2/2-way valve being possible for this purpose. Thus, for example, the solenoid valve can keep the 2/2-way valve currentlessly open or closed, so that, in the closed state of the injection valve, a return space receiving the end of the valve member located on the combustion-space side is pressureless or pressure-loaded. The intermediate stop keeping the valve member in a specific position opening only the lower injection-hole row can advantageously be designed as a hydraulic stop (closed bore) or as a □lechanical stop {activation of a second spring) . When the system pressure is used as a closing force, it is par¬ticularly advantageous to have on the valve member a tiydraulically adjustable closing piston, via the hydraulically adjustable axial extent of which a continu¬ously adjustable stroke distance of the valve member Is possible. At the same time, the fuel high pressure in the injection system or the position of the 2/2-way valve can De used as a control variable for the opening-stroke novement of the valve member.
In the event, the various control concepts have different advantages in dependence on the preconditions on the

interaal-combustion engine to be supplied, which is why only four design possibilities are explained although their features are interchangeable and can be combined with one another.
Accordingly, the present invention provides a fuel-injection device for internal-combustion engines, with a fuel high-pressure pump which feeds fuel out of a low-pressure space via a feed conduit into a high-pressure collecting space which is connected via hi^-pressure conduits to the individual injection valves projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an oirtward-opening injection-valve member, which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve, the injection valve member being loaded constantly by the injection pressure in the opening direction counter to a closing force, ::iiaracterized in that in the injection valve a control pressure space is provided, which s contiguous with a pressure surface arranged on the injection valve member and is lupplied with pressure medium from the high-pressure collecting space via a high iressure conduit and the pressure of which is capable of being adjusted in a controlled maimer, so as to vary th& closing force on the injection valve member by means of at ;ast one control valve which is inserted into tlie high-pressure conduit and/or into a ;lief conduit and which is controlled by the control means .
Further advantages and advantageous embodiments of the subject of the ivention can be taken from the description, with reference to the accompanying awin^ and the Patent claims.

Four exemplary embodiments of the fuel-injection device according to the invention for internal-combustion engines are represented in the drawing and are explained in more detail below-
Figure 1 shows a first exemplary embodiment with a hydraulic closing force on the valve member of the injection valve and with a currentlessly open 2/2-way solenoid valve. Figure 2 shows an enlarged sectional representation of the injection valve from Figure 1 in the region of the injection orifices. Figure 3 shows a second exemplary embodiment with a hydraulic closing force on the valve member, with a currentlessly closed 2/2-way valve and with a hydraulically adjustable closing piston, Figure 4 shows a third exemplary embodiment, in which the closing force is applied by a closing spring, with a 2/2-way solenoid valve currentlessly open, and Figure 5 shows a fourth exemplary embodiment, in which the 2/2-way solenoid valve is currentlessly closed and the closing force is generated by a 2-spring arrangement.
Description of the exemplary embodiments
The first exemplary embodiment of the fuel-injection device for internal-combustion engines, which is represented diagrammatically in Figure 1, has a fuel high-pressure pump 1 which feeds fuel out of a low-pressure space 3, preferably the fuel tank, via a feed conduit 5 into a high-pressure collecting space 7. High-pressure conduits 9 corresponding to the number of injection points lead off from this high-pressure collecting space 7 to the individual injection valves 11

projecting into the combustion space of the internal-
combustion engine to be supplied. The injection valves 11
lave a valve body 13, with a central bore 15, in which is
juided axially a piston-shaped valve member 17 having, at
Lts end located on the combustion-space aide, a closing
lead 19 proj ecting out of the bore 15 and forming a
ralve-closing member. At the same time, the closing head
.9, shown enlarged in Figure 2, has, on its side facing
:he valve body 13, a sealing face 21 which forms a
lealing edge and by means of which it cooperates with a
-alve-seat face 23 arranged on that end face of the valve
ody 13 located on the combustion-space side. The closing
ead 19 projects with a cross-section enlarged relative
o the piston shank of the valve member 17 Into a part of
idened diameter of the bore 15 and thus limits, with its
nd face 25 facing away from the combustion space, a
ressure space 27 which Is formed In the bore and which
xtends via an annular gap 29 between the wall of the
ore 15 and the valve-member shank as far as a fuel
ciflow duct 32 in the valve body 13. In this case, the
alarged cross-section on the closing head 19 is prefer-
sly formed by a sleeve 26 which Is fastened to the
Losing head 19 and which sealingly slides axially on the
ill of the bora 15. Provided in this sleeve 26 forming
movable valve slide are preferably two rows, located
dally one above the other, of injection orifices
Lnjection-hole rows) 28 which are arranged In such a way
lat, during the emergence of the valve member 17 from
be bore 15, a first lower row located near the combus-
Lon space is opened first after a specific idle stroke,
illst the second upper row comes out of overlap with the
are wall of the valve body 13 only during the further
live-member stroke. Moreover, recesses 30 between the
lve member 17 and sleeve 25 are provided for supplying
lel from the annular gap 29 to the injection orifices
I.
be annular gap 29 is limited, in the direction facing may from the closing head 19, by a housing web 31, in wich the diameter of the bore 15 decreases in such a way

cnac cue valve member 17 is sealingly guided allde-diaplaceably. This housing web 31 has adjoining it in the direction facing away from the combustion space a back¬space 3 3 which is formed by a renewed increase in diameter of the bore 15 and into which that end of the valve member 17 facing away from the combustion space projects and which is closed by means of a housing cover 35. At the same time, the valve member has^ at its end facing away from the combustion space, a. closing piston 37 which forms an actuating part and which slides seal¬ingly on the wall of the backspace 33 and thus divides the latter into a lower part space located on the combustion-space side and forming a return space 39 and an upper part space facing away from the combustion space and forming a relief space 41, the lower annular end face of the closing piston 37 located on the combustion-space side forming a pressure application surface 43 of the valve member 17 in the closing direction, the said pressure application surface being larger than the end face 25 acting in the opening direction and located on the closing head 19.
To supply fuel to the injection valve 11 and to control the opening-stroke movement of the outward-opening valve member 17, the high-pressure conduit 9 branches, near the injection valve 11, into two part conduits, of which a first part conduit 45 opens in an unthrottled manner into the fuel inflow duct 32 and further into the pressure space 27 and a second part conduit 47 opens into the return space 39 of the backspace 33, the second part conduit 47 being closable by means of a 2/2-way valve 49 inserted therein and controllable by means of an electromagnet.
To relieve the upper relief space 41 of the backspace 33 of pressure, a relief conduit 51 leads off from the latter into the low-pressure space 3.
To control the opening-stroke movement, a spill conduit 53 leads off from the lower return space 39 and opens into the backspace 33 in such a way that it cannot be closed by the closing piston 37 during its stroke

movement/ and into which is inaerted a control solenoid valve 55 which is designed as a 2/2-way valve and which opens the spill conduit 53 into the low-pressure space 3 or closes it and can, at the same time, be used for a plurality of injection valves.
Furthermore, a throttle conduit 59 containing a res¬triction 57 leads off from the return space 39 into the low-pressure space 3, the mouth of the said throttle conduit being arranged in the return space 39 in such a way that, after a specific opening-stroke distance has been covered, it can be closed by the closing piston 37, this opening-stroke position of the valve member 17 then corresponding to the opening of the lower injection-hole row.
To limit the maximnjm opening-stroke distance of the valve member 17, a stop sleeve 61 is inserted into the return space 39, the upper annular face of which stop sleeve forms a stop cooperating with the pressure surface 43 of the closing piston 37, the said stop sleeve having passage orifices for the second part conduit 47 and for the spill conduit 53.
The first exemplary embodiment represented in Figures 1 and 2 works as follows.
In the closed state of the injection valve 11, the 2/2-way valve 49 is open (electromagnet currentless), so that the fuel high pressure built up by the high-pressure pump 1 in the high-pressure collecting space 7 continues into the return space 39 of the backspace 33. The high pres¬sure applied to the pressure surface 43 of the closing piston 37 keeps the valve member 17 pressed with its sealing face 21 onto the valve-seat face 23. To open the injection valve 11, the 2/2-way valve 49 (live) breaks the connection between the backspace 33 and the high-pressure collecting space 7. The high pressure in the lower return space 39 is reduced via the throttle conduit 59, this operation and therefore the opening-stroke trend of the valve member 17 being capable of being set via the throttle 57. With the reduction of the closing force acting on the valve member 17, the opening

pressure prevailing in the pressure space 27 and acting on the valve member 17 via the face 25 is now sufficient to lift off the valve member 17 from the valve seat 23 and to expose the injection orifices 28.
At the same time, the valve member 17 is initially displaced only until the closing piston 37 closes the throttle conduit 59 and the now closed lower return space 39 forms a hydraulic stop, in this position the lower injection-hole row being opened. If the opening stroke of the valve member 17 is to be continued, the control valve 55 opens the spill conduit 53 and the pressure in the lower return apace 3 9 is expanded into the low-pressure space 3, so that the valve member 17 can cover i ts maximum opening distance, until the closing piston 37 comes to bear on the stop sleeve 61, and at the same time also opens the second upper injection-hole row of the injection, orifices 28. If the valve member 17 is to be prevented from waiting in the intermediate position, it is possible, by an immediate opening of the spill conduit 53, to execute a rapid maximum opening stroke. For a renewed closing of the injection valve 11, the 2/2-way valve is opened again, so that, with the spill conduit 53 now closed, the fuel high pressure builds up once again in the lower return space 39 and displaces the valve member 17 back onto its valve seat 23.
The second exemplary embodiment represented in Figure 3 differs from the first only in the type of control of the opening-stroke movement of the valve member, which is why this description deals only with these components, identical components being designated in a similar way to the first exemplary embodiment. In this case, a restriction 63 is inserted into the second part conduit 47 branching off from the high-pressure conduit 9 and opening into the lower return space 39. Moreover, a control conduit 65 leads off from :he return space 39, the said control conduit opening Lnto the low-pressure space 3 and being closable by means of the electromagnetically controlled 2/2-way valve 49 now inserted therei

In Figure 3, the closing piston 37 is of two-part design, an upper piston part 67 which faces away from the combus¬tion space being fixedly connected to that end of the valve member 17 projecting into the backspace 33, and a lower piston part 69 which faces the combustion space being guided axially diaplaceably on the valve-member shank. The space enclosed between the piston parts 67, 69 forma a setting space 71 which can be filled with fuel via a fuel conduit 73 fed from the low-pressure space 3 and having a non-return valve 75 opening in the direction of the setting space 71 and which can be relieved into bhe low-pressure space 3 via a part conduit 77 which pranches off from the fuel conduit 73 and which can be opened by means of a control valve 79.
A compression spring 61 clamped between the piston parts 57, 69 displaces the piston parts 67, 69 into their unitlal position when the backspace 33 is relieved, the second exemplary embodiment represented in Figure 3 borks as follows.
with the injection valve 11 closed, the 2/2-way valve 49 nserted into the control conduit 65 is closed {current-ess} , so that the fuel high pressure builds up in the eturn space 39 via the second part conduit 47 and loads he lower piston part 69 in the closing direction of the alve member 17. At the same time, depending on the illing of the setting space 71, this closing force is ransmitted directly or via a hydraulic cushion to the pper piston part 67 fixed to the valve member, so that he valve member 17 is held against the valve seat 23. or opening the injection valve 11, the 2/2-waY valve 49 live) opens, so that the pressure in the return space 3 9 xpands into the low-pressure space 3. As a result of tiis, the pressure in the pressure space 27 acting on the alve member 17 in the opening direction is sufficient to ift off the valve member 17 from its seat 23, this pening-stroke movement continuing until the lower piston art 69 comes to bear on the stop sleeve 61. A variable broke control of the valve member, particularly a iiting of the valve member 17 in the position in which

only the lower injection-hole row ia opened, is achieved by means of a specific filling of the setting space 71, for which purpose this hydraulic volume is filled up completely via the fuel conduit 73 for a minimum stroke and is correspondingly emptied via the control valve 79 for a maximum stroke, intermediate positions also being possible as result of a suitable filling of the setting space 71.
The closing of the injection valve 11 takes place by means of a renewed closing of the 2/2-way valve 49, with the result that the closing pressure builds up again in the return space 39 of the backspace 33 and the valve member 17 is moved back onto its valve seat 23.
The third exemplary embodiment represented in Figure 4 differs from the preceding exemplary embodiments in the type of closing force which is applied to the valve member 17 and which is generated here by means of a spring force.
For this purpose, there is arranged in the backspace 33
a valve spring 83 which is clamped between a spring plate
85 located at that end of the valve member 17 facing away
from the combustion space and an annular shoulder 87
limiting the backspace 33 on the combustion-space side
and which keeps the valve member 17 in bearing contact on
the valve seat 23 counter to the fuel high pressure
prevailing in the pressure space 27 and loading the valve
member 17 in the opening direction. In this case, a
relief conduit 51 leads off from the backspace 33, the
said relief conduit opening into the low-pressure space
3 and being closable via the 2/2-way valve 49 inserted
therein. Moreover, between the backspace 33 and 2/2-way
iralve 49, the second part conduit 47 forming a connecting
=onduit between the high-pressure conduit 9 and the
sackspace 33 opens into the relief conduit 51, a restric-
;ion 57 being inserted in the second part conduit 47 in
-.he third exemplary embodiment of the fuel-injection
levice according to the invention.
:he third exemplary embodiment represented in Figure 4 rorks as follows.

With the injection valve 11 in the closed state, the 2/2-way valve 49 arranged in the relief conduit 51 or in the second part conduit 47 is open (currentless) , so that no fuel high pressure can build up in the backspace 33 and the valve spring 83 keeps the valve member 17 on the valve seat 23 coimter to the fuel high pressure prevail¬ing in the pressure space 27 and acting on the valve member 17 in the opening direction. For opening the injection valve 11/ the 2/2-way valve 49 closes the pressure-relieving connection, between the backspace 33 and low-pressure space 3, so that the fuel high pressure of the injection system builds up in the backspace 33 via the second part conduit 47. At the same time, the result¬ant pressure force in the opening direction of the valve member 17, which is now applied to the valve-member part projecting into the backspace 33, in conjunction with the pressure force prevailing in the pressure space 27, is higher than the return force of the valve spring 83, so that the valve member 17 is lifted off from the valve seat 23 and exposee the injection orifices. A waiting of the valve member 17 in a position, in which only the lower injecticn-bole row is initially opened, can be achieved, for example, via a progressive characteristic of the valve spring 83 or a specific idle stroke, the fuel high pressure of the high-pressure collecting space being used as a control pressure.
For closing the injection valve at the end of the injec¬tion operation, the 2/2-way valve 49 once again opens the relief conduit 51 into the low-pressure space 3, so that the fuel high pressure in the backspace 33 expands rapidly and the valve spring 83 moves the valve member 17 back onto the valve seat 23.
In the fourth exemplary embodiment represented in Figure 5, the second part conduit 47 starting from the ligh-pressure conduit 9 opens directly into the backspace 33, the second part conduit 47 being cloeable by means of -he 2/2-way valve inserted therein. The pressure relief 3f the backspace 33 takes place by means of the relief ;onduit 51 which leads off from the latter into the

low-pressure space 3 and which, in the fourth exemplary embodiment, has a restriction 57.
The closing or return force on the valve member 17 is generated via a 2-spring arrangement, for which purpose an annular step 89 is provided on the shank part of the valve member, the said shank part projecting into the backspace 33, between the spring plate 85 arranged at the end located on the combustion-space side and the annular shoulder 87 limiting the backspace 33. In this case, a first valve spring 91 is clamped between the spring plate 85 and the annular step 89 and a second valve spring 93 is clamped between the annular step 89 and the annular shoulder S"? fixed to the housing, the spring rigidity of the first valve spring 91 being lower than that of the second valve spring 93. For setting the pre-stroke movement of the valve member 17 executed counter to the force of the first valve spring 91, in the exemplary embodiment described there is fastened to the spring-side annular end face of the spring plate 85 a sleeve 95, of which the end face facing away from the spring plate 85 bears on the annular step 89 after the execution of a pre-stroke movement and which then, cutting out the first valve spring 91, makes a rigid connection between the spring plate 85 and annular step 89, so that, during the further opening stroke, only the second valve spring 93 takes effect. This waiting in an intermediate position 3an alternatively also be achieved without a sleeve 95, Ln which case both valve springs are effective during the remaining s troke■
The fourth exemplary embodiment represented in Figure 5 torka as follows-
iith the injection valve 11 closed, the 2/2-way valve 49 .nserted into the conduit 47 is closed (currentlees), so :hat the backspace 33 is relieved to a specific pressure -^ia the relief conduit 51 containing a specific throttle 17. In this case/ the valve member 17 is kept in bearing lontact on the valve seat 23 coxinter to the pressure in he pressure space 27 by the force of the valve springs 1, 93. If injection is to take place, the 2/2-way valve

opens, so that the fuel high pressure of the inj ection system builds up in the backspace 33 and, as described with regard to Figure 4, moves the valve member 17 in the opening direction. A pre-stroke until the sleeve 95 comes to bear on the annular step 89 ia first executed counter to the lower spring force of the first valve spring 91, the said pre-stroke being sufficient to open the lower injection-hole row on the valve member 17. The valve member 17 can be kept in this position by the timed activation of the 2/2-way valve 49 in order to maintain a constant pressure in the backspace 33. If the total injection cross-section on the valve member 17 is to be opened, the supply of pressure into the backspace 33 is not interrupted, so that the fuel pressure in the back¬space 33 rises in such a way that the valve member 17 is displaced further, counter to the force of the second valve spring 17, into a position in which the second upper injection-hole row is also opened.
for the subsequent closing of the injection valve 11, the 2/2-way valve 49 is closed once again, so that the high pressure in the backspace 33 is expanded into the low-pressure space 3 via the relief conduit 51 and the valve springs 91, 93 move the valve member 17 back onto its leat 23.
:n all the alternative versions, the actuation of the 2/2-way control valves 49 takes place by means of an lectromagnet which is activated by an electronic control nit (not shown), the control unit processing in a known may a multiplicity of operating parameters of the nternal-combustion engine to be supplied.
It ia thus possible in a constructively simple ay to combine the advantages of a "common-rail" injec-ion system with the advantages of an injection valve of he outward-opening type, so that, in addition to a reely selectEQile variable start of injection and end o£ njection and, a variable injection pressure, a variable ejection cross-section can also be set freely over the itire characteristic map of the internal-combustion igine to be supplied, this fuel-injection device being

controllable in a simple way by means of a 2/2-way valve.

WE CLAIM:
1. A fuel-injection device for intemal-combustion engines, with a fuel high-pressure pump (1) which feeds fuel out of a low-pressure space (3) via a feed conduit (5) into a high-pressure collecting space (7) which is connected via high-pressure conduits (9) to the individual injection valves (11) projecting into the combustion space of the internal-combustion engine to be supplied, the injection valves having an outward-opening injection-valve member (17), which executes controllable opening strokes in the direction of the combustion space by an actuating means controlled by a control means and at the same time opens a variable injection cross section on the injection valve (11), the injection valve member (17) being loaded constantly by the injection pressure in the opening direction counter to a closing force, characterized in that in the injection valve (11) a control pressure space (39, 33) is provided, which is contiguous with a pressure surface (43, 69, 85) arranged on the injection valve member (17) and is supplied with pressure medium from the high-pressure collecting space via a high pressure conduit (47) and the pressure of which is capable of being adjusted in a controlled manner, so as to vary the closing force on the injection valve member by means of at least one control valve (49, 55, 79) which is inserted into the high-pressure conduit and/or into a relief conduit (53, 73) and which is controlled by
the control means.
2. The fuel-injection device according to claim 1, wherein the valve member
(17) has a valve shank which is guided through a bore (15) of a valve body (13) of the
injection valve (11) and which has, at its end located on the combustion-space side, a
closing head (19) which projects out of the bore (15) and forms a valve-closing
member and which, on its side facing the valve body (13), has a sealing face (21)
which forms a sealing edge and by means of which it cooperates with a valve-seat
face (23) arranged on that end face of the valve body (13) located on the combustion-
space side, and with a pressure space (27) which is connected to the high-pressure
conduit_

(9) and is arranged between the shank of the valve member (17) and the wall of the bore (15) and which is limited towards the combustion space by the closing head (19), there being arranged on the valve member (17) an axially pointing pressure surface (25) limited between the valve seat (23) and the valve shank.
3. The fuel-injection device according to claim 2, wherein the injection cross-section on the injection valve (11) is controlled by a slide-valve arrangement, the movable slide part of which is adjusted together with the valve member (17) and the orifice cross-section of which, forming the injection cross-section, is located upstream of the valve seat (23).
4. The fuel-injection device according to claim 3, wherein the injection cross-section is opened only after the execution of a specific stroke of the valve member (17) in the opening direction.
-■*
5. The fuel-injection device according to claim 3, wherein part of the
valve member (17) is designed as the movable slide part which is guided in
the bore (15) in the region of the closing head (19) and which has two rows,
located axiaily one above the other, of injection orifices (28) which are
distributed over its circumference and which, starting from the pressure
space (27), are arranged in such a way that, during the opening-stroke
movement of the valve member (17), the outlet orifices of the injection
orifices (28) offset axiaily relative to one another can be opened towards the
combustion space in succession as a result of emergence from overlap with
the bore (15) at the control edge formed by the valve-seat face (23).

6. The fuei-injection device according to claim 2, wherein the valve
member (17) is connected, at its end facing away from the combustion
space, to an actuating part which limits, in the valve body (13), a backspace
(33) connectable to the high-pressure conduit (9), the opening movement
and/or closing movement of the valve member (17) being controllable by the
control valve at least in operative connection via the high-pressure filling or
high-pressure relief of the said backspace.
7. The fuel-injection device according to claim 1, wherein the control
valve controlling the opening and closing movement of the injection valve
(11) and located in the high-pressure conduit is designed as an electrically
controlled directional valve (49).
8- The fuel-injection device according to claim 1, wherein the electrically controlled directional valve (49) is a solenoid valve.
9. The fuel-injection device according to claim 6, wherein the
injection valve (11) is connected to the high-pressure collecting space (7) via
two part conduits, of which a first part conduit (45) constantly connects the
pressure space (27), formed between the valve member (17) and bore (15)
and acting on the valve member (17) in the opening direction, to the high-
pressure collecting space (7) and a second part conduit (47) opens into a
return space (39) separated from the pressure space (27), the filling of this
return space (39) with fuel which is under high pressure being controllable
by means of the control valve designed as an electrically controlled
directional valve (49).

10. The fuel-injection device according to claim 9, wherein the actuating part of the valve member (17) has a closing piston (37), of which the end face located on the combustion-space side has a pressure application surface (43), via which the valve member (17), can be loaded in the closing direction and which is larger than the pressure surface (25) acting in the opening direction and located on the valve member (17), the closing piston (37) sliding sealingly on the wall of the backspace (33) and thus dividing the latter, in the valve body (13), into an upper relieved relief space (39, 41) facing away from the combustion space and the lower return space (39) facing the combustion space.
11. The fuel-injection device according to claim 10, wherein the electrically controlled directional valve (49) is inserted into the second part conduit (47) of the high-pressure conduit (9).
12. The iuel-injection device according to claim 11, the directional
valve (49) is designed as a 2/2-way valve, and the return space (39) is
constantly connected to the low-pressure space (3) via a throttle conduit (59)
containing a throttle (57).
13. The fuel-injection device according to claim 10, wherein a spill
conduit (53) which cannot be closed by the closing piston (37) during its
stroke movement leads off from the return space (39) into the low-pressure
space (3) and can be opened and closed by means of an electrically
controlled valve (55),

14. The fuel-injection device according to claim 12, wherein the throttle
conduit (59) from the return space (39) into the low-pressure space (3) is closed
by the closing piston (37) after an opening-stroke distance of the valve member
(17), opening the lower row of injection orifices (28) on the combustion-space
side has been covered.
15. The fuel-injection device according to claim 10, wherein there is
provided in the return space (39) a stroke stop (61), onto which the closing
piston (37) comes to bear with its pressure application surface (43) after the
execution of a maximum opening-stroke movement.
16. The fuel-injection device according to claim 10, wherein a restriction
(63) is arranged in the second part conduit (47) to the high-pressure conduit (9),
and in that spill conduit (65) leads off from the return space (39) into the low-
pressure space (3) where a directional valve (49) is arranged in the spill conduit
(65), said spill conduit (65) can be closed by the directional valve (49)
controlling the opening and closing movement of the valve member (17).
17. The fuel-injection device accordmg to claim 15, wherein the axial
length of the closing piston (37) in the direction of the lower return space (39)
can be varied.
18. The fuel-injection device according to claim 17, wherein the closing
piston (37) is formed from two piston parts, of which an upper piston

part (67) facing away from the combustion space is fixedly connected to the valve member (17) and a lower piston part (69) facing the combustion space is guided axially displaceably on the shank of the valve member (17), there being enclosed between the piston parts (67, 69) a setting space (71), from which a fuel conduit (73) operable by an electrically controlled valve (79) leads off into the low-pressure space (3), and with a compression spring (81) clamped between the piston parts (67,69) and located in the setting space (71).
19. The fuel-injection device according to claim 9, wherein the shank of the valve member (17) is sealingly guided in a part of the bore (15) which limits the backspace (33), and in that the valve member (17) has, at its end facing away from the combustion space and penetrating into the backspace (33), a spring plate (85), between which and an annular shoulder (87) formed at the transition of the bore (15) into the backspace (33) is clamped a valve spring (83) which loads the valve member (17) in the closing direction.
^ 20. The foel-injection device according to claim 19, wherein a restriction
(57) is provided in the second part conduit (47), and in that a relief conduit (51)
into the low-pressure space (3) branches off from the second part conduit (47),
from the backspace (33), into which relief conduit (51) is inserted an electrically
controlled directional valve (49) controlling the opening movement of the valve
member (17).

21. The fuel-injection device according to claim 9, wherein the valve
member (17) has, at its end facing away from the combustion space, a spring
plate (85), between which and that wall of the backspace (33) formed by an
annular shoulder (87) of the bore (15) in the valve body (13) is clamped a
valve-spring arrangement which is formed from two springs (91, 93) and
which load the valve member (17) in the closing direction and take effect in
succession during the opening-stroke movement of the valve member (17).
22. The fuel-injection device according to claim 19 or 21, wherein the
directional valve (49) controlling the opening movement of the injection
valve (11) is inserted into the second part conduit (47) opening into the
backspace (33), and in that a relief conduit (51) into the low-pressure space
(3), the said relief conduit containing a restriction (57), leads off from the
backspace (33).
23. A fuel-injection device for internal-combustion engines
substantially as herein described with reference to the accompanying
drawings.

Documents:

1469-mas-95 abstract.jpg

1469-mas-95 abstract.pdf

1469-mas-95 claims.pdf

1469-mas-95 correspondence others.pdf

1469-mas-95 correspondence po.pdf

1469-mas-95 description (complete).pdf

1469-mas-95 drawings.pdf

1469-mas-95 form-1.pdf

1469-mas-95 form-26.pdf

1469-mas-95 form-4.pdf

1469-mas-95 form-9.pdf

1469-mas-95 petition.pdf

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Patent Number

193140

Indian Patent Application Number

1469/MAS/1995

PG Journal Number

35/2005

Publication Date

16-Sep-2005

Grant Date

10-May-2005

Date of Filing

14-Nov-1995

Name of Patentee

ROBERT BOSCH GMBH

Applicant Address

POSTFACH 30 02 20, 70442 STUTTGART FEDERAL

Inventors:

#	Inventor's Name	Inventor's Address
1	DETLEV POTZ	HERDWEG 100, 70193 STUTTGART
2	NESTOR RODRIGUEZ-AMAYA	DENNERSTR. 70, 70372 STUTTGART
3	GUENTER LEWENTZ	HIRSCHSTR. 27, 71282 HEMMINGEN,
4	RALF MAIER	FRANZ-CZISCH-STR. 17, 73529 SCHWAEBISCH GMUEND
5	STEFAN KAMPMANN	PANORAMASTR. 9,70839 GERLINGEN
6	UWE GORDON	DAIMLERSTR. 18,71706 MARKGROENINGEN
7	ANDREAS KREH	DEIDESHEIMER STR. 61, 70499 STUTTGART

PCT International Classification Number

F02M45/12

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA