Title of Invention

"DRIVE DEVICE FOR A DUAL-CYLINDER SLURRY PUMP AND METHOD FOR OPERATING SAID PUMP"

Abstract

The invention relates to a method for operating a drive device for a dual-cylinder slurry pump and to a drive device for a dual-cylinder slurry pump, comprising two drive cylinders that are actuated by means of a fluid (1, 2), said cylinders alternately charging a common delivery line with slurry, in particular concrete, via a pipe switch (RW), in particular indirectly by means of driven delivery cylinders (FR, FL). According to the invention, the pipe switch is likewise actuated by means of a fluid using an actuatorcylinder (SZ) and as early as the final displacement of the piston of each drive cylinder in its stroke, prior to said piston reaching its final position, at least part of the fluid stream that is provided to actuate the drive cylinder is used to actuate the actuator cylinder.

Full Text

Drive Device for a Dual-Cylinder Slurry Pump and Method for Operating Said Pump The present invention relates to a method for operating a dual-cylinder slum' pump and a drive device for a dual-cylinder slum1 pump in accordance with the generic pan of claim 1 and the generic part of claim 8. Dual-cylinder slurry pumps are used, for example, to pump concrete. For this, the concrete is pumped over substantial heights and distances, e.g., via corresponding distributing masts. In such dua]-cylinder slum pumps, the deliver}' cylinders are connected via a switch, especially a pipe switch, to a common delivers line, with the switch alternately connecting the one or the other delivery cylinder to the delivery line, such that overall the flow of slum1 or concrete is virtually continuous. However, the unavoidable changes of connection between the delivery cylinders to the common delivery1 line by means of the switch create brief interruptions in delivery during the switching operations. This may be seen for example in the block diagram of Fig. 2, which shows an hydraulic drive for a dual-cylinder slurry pump with a pipe switch. This is a block diagram of a so-called single-circuit system in which the drive cylinders 1,2 of the delivery cylinders FR, FL and the actuator cylinder SZ of the pipe switch are supplied with hydraulic oil by means of one supply device only or in which the working pressure is generated. This sole supply device has two pumps PI and P2. which are connected via oil lines LI and L2 to the switching block 3, which, depending on the operating status, makes the oil delivered by pumps PI and P2 available to the drive cylinder 1 or the drive cylinder 2 for the delivery cylinders FR and FL via lines L4 or, via further lines L4a, to the actuator or swiveling cylinder SZ of the pipe switch RW. However, relatively long switching operations occur here because it is only after a stroke of the drive cylinder 1 or 2 that the control block 3 switches such that the full pump capacity of the pumps PI and P2 is made available to the actuator or swiveling cylinder SZ. Only after the pipe switch has swivelled due to actuation of the actuator or swiveling cylinder SZ is the full pump capacity of the pumps PI and P2 then made available again to the drive cylinders 1 or 2 by switching in the control block 3. It is known from the prior art that such long switching times can be avoided with a so-called dual-circuit system (see Fig. 3) in which the pumps PI and P2 are provided separately for the drive cylinders 1 and 2 of the delivery cylinders FR and FL on one hand, and for the actuator or swiveling cylinder SZ of the pipe switch RW on the other. Thus, a so-called dual-circuit system has two independent pump devices, each having at least one pump PI and P2. This means it is possible to actuate the delivery cylinders and the actuator cylinder(s) in parallel time to shorten the interruption in pumping. However, the disadvantage here is the need for two separate pump devices, with pump PI especially needing a design large enough to provide the necessary hydraulic volume flow to operate drive cylinders 1 and 2. It is therefore the object of the present invention to ensure rapid switching of the switch for connecting the two deliver}' cylinders to the common delivery line, while minimizing the outlay on switching and the outlay on the hydraulic drive of the drive or delivery cylinders and of the actuator cylinder for the switch. This object is solved by a method and a drive device having the characteristics of claims 1 and 8. Advantageous embodiments are the object of the dependent claims. The invention draws on the knowledge that when a fluid, especially an hydraulic oil, is used to drive the drive cylinders or deliver)' cylinders of a dual-cylinder slurry pump, full drive power is no longer needed toward the end of the piston displacement, that is at the end of a stroke. Armed with this knowledge, it is possible to use the superfluous drive power to shorten the switching time in such a way that the superfluous drive power can already be used for the actuation of the switch, especially for the drive of a swiveling or actuator cylinder for a pipe switch. Consequently, it is no longer necessary to wait for the stroke in the drive or deliver)' cylinder to finish, but rather the switching operation and thus the actuation of the pipe switch can be initiated already before the end of a stroke, For this purpose, the invention provides for monitoring or determining the position of the piston in the drive cylinder or delivery cylinder, and for locating it, at least in a certain position shortly before it reaches the final position, such that, starting with this information, some of the fluid volume flow, preferably hydraulic oil volume flow, can be made available for actuation of the actuator or swiveling cylinder of the switch. The device employed for the determination may be of a mechanical, electrical or hydraulic type, with the last-mentioned especially suitable when overall control over the drive proceeds largely by means of a fluid or hydraulic oil. In that case, it is a simple matter to use corresponding switching valves that are activated via known hydraulic control lines. Further, in a preferred embodiment, a corresponding device for locating the piston position of the actuator cylinder of the pipe switch may be provided in order that this information may be used for the switching operation. Preferably, the hydraulic switch may be constructed such that two pump devices are used for providing a corresponding fluid stream or operating pressure, which said pump devices, in a manner comparable to the dual-circuit system, are used primarily independently for the drive of the drive cylinders on one hand and for the drive of the actuator or swiveling cylinder for the switch on the other. On account of the idea of the invention, namely that the drive power for the drive or deliver)' cylinder no longer has to be 100% shortly before the necessary switching operation of the switch, the two independent pump devices may be combined with each other in a manner such that, during the stroke of the drive cylinder or the delivery cylinder, the second pump device makes its capacity available for the drive or deliver}' cylinder, whereas, short!)' before the switching operation, the second pump device is used exclusively for actuation of the actuator or swiveling cylinder of the switch. In this way, it is possible to use the pump or pump capacity of the drive effectively - and to use components of lower capacity. Preferably, the drive is designed such that the operating pressure, especially of the second pump device, is available at the actuator or swiveling cylinder during the entire operation. Diversion of the fluid volume flow may be realized simply by a corresponding switching valve, so that the overall switching outlay can be kept very low. Although the device is described below using the example of an hydraulic drive with hydraulic oil as fluid, it goes without saying that the invention is also feasible with other suitable fluids and corresponding devices for pressure generation and/or fluid delivery. Further advantages, characteristics and features of the present invention are apparent from the following details description of an embodiment using the enclosed drawings. The drawings show in purely schematic form Fig. 1 a block diagram of the drive device of the invention; Fig. 2 a block diagram of a known single-circuit system; and in Fig. 3 a block diagram of a known dual-circuit system. Fig. I shows a block diagram of an hydraulic drive of a dual-cylinder slurry pump with a first drive cylinder 1 and a second drive cylinder 2, which are connected via the corresponding pistons to a first deliver)' cylinder FR and a second delivery cylinder FL. The delivery cylinders FL and FR are connected via a pipe switch RW to a common delivery line, such that alternating strokes of the delivery cylinders FL and FR provide almost continuous pump capacity for the slurry. For this purpose, the pipe switch RW must be brought via an actuator or swiveling cylinder SZ into a connecting position such that it alternates between the first delivery cylinder FR and common delivery line and the second delivery cylinder FL and common deliver)' line, The hydraulic drive is supplied by two pump devices PI and P2, each of which may have one or more pumps connected in parallel. The block diagram shows only one pump for each pump device. The pump devices Pi and P2 are connected via the supply lines LI and L2 to the control block 3 in which the switching valves 3.1 and 3.2 are accommodated, which in turn are connected to hydraulic lines L4 and L4a. For mutual connection between the supply lines LI and L2. a link line with switching valve 6 is provided, such thai hydraulic oil, which in the supply line LI is pumped through the first pump device PL can be pumped into the second supply line L2. However, the switching valve 6 especially ensures that hydraulic oil. which is pumped from the second pump device P2 in the supply line L2. can pass into the first supply line LI to maintain a sufficient oil flow to actuate the drive cylinders 1 and 2. Switching valve 3.2 then makes the hydraulic oil in the supply line LI alternately available to the first drive cylinder 1 and the second drive cylinder 2 via the supply lines L4 in order that the delivery cylinders FR and FL may be actuated via said drive cylinders. The oil returns via line L9. Switching valves VFR and VFL for controlling the alternating stroke displacement of the drive cylinders 1 and 2 are provided at drive cylinders 1 and 2. Because of the alternating stroke displacement of the drive cylinders 1 and 2, these are coupled hydraulically to each other via the control lines SL5, SL6, SL7 and SL9. The switching valves VFR and VFL additionally form so-called proximity switches by means of which the piston position in the drive cylinders 1 and 2 can be determined. Simultaneously, through the corresponding positions of the piston in the drive cylinders 1 and 2, the control lines SL8 and SLID connected to the switching valves VFR and VFL are pressurized accordingly, which in turn correspondingly drive the switching valves 3.1 and 3.2 in the control block 3. or the switching valve 6. This occurs in a manner such that, during a change of deliver)' stroke from the delivery cylinder FR to the deliver)' cylinder FL or vice versa, the pipe switch has to be actuated accordingly by the actuator or swiveling cylinder SZ. For this purpose, switching valve 3.1 supplies the actuator cylinder SZ with corresponding hydraulic oil or pressure through the second pump device P2 and the supply lines L2 and L4a. To obtain the fastest possible switching, before attainment of the respective final stroke position of the drive cylinder 1 or 2 triggered by the hydraulic signals by means of the control lines SL8 and SLID, the switching valve 3.1 and the switching valve 6 are correspondingly switched via the switching valve 6. For this, the switching valve 6 blocks the connecting line between the supply lines LI and L2 such that oil can no longer flow from the supply line L2 into the supply line LI and thus supply the drive cylinders 1 and 2. Instead, the full pump capacity of the second pump device P2 is made available to the swiveling cylinder SZ. with the switching valve VSZ for controlling the actuator or swiveling cylinder SZ also being actuated through the corresponding hydraulic control lines SL18 and SL19, or sending corresponding control signals to the switching valve 6. The use of the switching valve 6 enables the oil volume flow, which is normally also used by the pump device P2 to actuate the drive cylinders 1 and 2 and which is no longer absolutely necessary in the final displacement of the respective drive cylinders 1 and 2, to be used earlier to actuate the actuator cylinder such that an interruption to the pumping of the slurry pump is reduced. Moreover, since the second pump device P2 is directly connected via the supply line L2 to the switching valve 3.1 or via the hydraulic lines L4a to the swiveling or actuator cylinder SZ, the operating pressure of the second pump device P2 is immediately available to the swiveling cylinder SZ during the entire operation. The embodiment shown is thus an advantageous combination of a single-circuit and a dual-circuit system in which the pump capacity of the second pump device is variably used both for the actuation of the drive cylinders 1 and 2 and of the swiveling or actuator cylinder SZ. Especially al the end of a piston displacement, when the full pump capacity of the pump devices down to the final position is not necessary for the actuation of the drive cylinder, the advantageous possibility thereby rises of making some of the oil volume flow available for the actuation of the actuator or swiveling cylinder of the pipe switch in order that any interruption of the pump flow may be shortened to a minimum. MODIFIED CLAIMS [received by the International Office on August 24, 2005 (08.24.2005); orginal claims 1-13 replaced by modified claims 1-16] WITH EXPLANATION WE CLAIM: 1. Method for operating a dual-cylinder slurry pump, preferably for conveying concrete, com- prising two alternately actuated delivery cylinders (FL, FR), which charge a common delivery line with slurry via a switch (RW), wherein the delivery cylinders (FR, FL) are actuated via a drive cylinder (1, 2) by means of a fluid and the switch (RW) is actuated via an actuator cylinder also by means of a fluid, wherein a first pump device (P1) is provided, whose fluid volume flow is provided by means of a first supply line (L1) primarily to the drive cylinders (1,2) and a second pump device (P2), whose fluid volume flow is provided by means of a second supply line (L2) primarily to the actuator cylinder (SZ), characterized by the fact that, during the piston stroke of a drive cylinder (1,2), at least some of the fluid volume flow of the second pump device (P2) transfers to the fluid volume flow of the first pump device (P1) for the drive cylinders (1,2). 2. Method as claimed in claim 1, whereinthe fluid volume flow in the second supply line to the swiveling cylinder (L2) or a part thereof can transfer into the first supply line to the drive cylinders (L1) via a link line in which a switching device is installed. 3. Method as claimed in claim 1 or claim 2, wherein the fluid volume flow in the first supply line (L1) is made alternately available to the first drive cylinder (1) or the second drive cylinder (2) by a switching valve (3.2). 4. Method as claimed in any of the previous claims, wherein just before the final position of a drive cylinder (1,2) is reached, the switching device blocks the link line between the supply lines (L1) and (L2), such that fluid volume flow can no longer transfer from the second supply line (L2) into the first supply line (L1). 5. Method as claimed in any of the previous claims, wherein the final piston position in the drive cylinders (1, 2) is determined by means of a proximity switch, in order that the switching device may be driven accordingly. 6. Method as claimed in any of the previous claims, wherein the fluid volume stream is generated by l or 2 pump devices (P1, P2) each with one or more pumps. 7. Method as claimed in any of the previous claims, wherein the fluid is hydraulic oil. 8. Method as claimed in any of the previous claims, wherein the drive cylinders (1,2), the actuating cylinder (SZ) and/or the switching valves needed for operation are controlled hydrauli-cally. 9. Dual-cylinder slurry pump comprising a drive device with two drive cylinders (1, 2) that are actuated by means of a fluid, said cylinders alternately charging a common delivery line with slurry, especially concrete, via a switch (RW), especially a pipe switch, especially indirectly via driven delivery cylinders (FR, FL), with the pipe switch also being actuated via an actuating cylinder (SZ) by means of a fluid, especially for performing the method in accordance with any of the previous claims, with a first pump device (P1) by means of which the fluid is provided via a first supply line (L1) under working pressure primarily to the drive cylinders (1, 2) and with a second pump device (P2) by means of which the fluid is provided via a second supply line (L2) under working pressure primarily to drive the actuating cylinder (SZ), wherein a determination device (VFR, VFL) for locating at least one piston position of each drive cylinder is provided, the determination device (VFR, VFL) is designed such that the piston position in the final displacement region is determined before the final position of the stroke is reached, characterized by the fact that, a link line is provided between said first and second supply lines (L1, L2) for mutually connecting them, installed in which a switching device (6) for diverting at least part of the fluid stream generated by at least one pump device (P1, P2), in such a way that fluid from said first supply line (L1) can pass over in said second supply line (L2) and that during a stroke of one drive cylinder (1, 2) fluid can pass over from said second supply line (L2) in said first supply line (L1), wherein said switching device (6) is actuated by determination of the piston position by means of said determination device (VFR, VFL). 10. Dual-cylinder slurry pump as claimed in claim 9, wherein the fluid is hydraulic oil. 11. Dual-cylinder slurry pump as claimed in claim 9 or claim 10, wherein the determination device (VFR, VFL) has one or more mechanical, electrical or hydraulic sensors for deter mining the piston position.

Documents:

6879-delnp-2006-Abstract-(21-04-2011).pdf

6879-delnp-2006-abstract.pdf

6879-delnp-2006-Claims-(21-04-2011).pdf

6879-delnp-2006-claims.pdf

6879-DELNP-2006-Correspondence Others-(04-11-2011).pdf

6879-delnp-2006-Correspondence-Others-(04-04-2011).pdf

6879-delnp-2006-Correspondence-Others-(21-04-2011).pdf

6879-delnp-2006-correspondence-others-1.pdf

6879-delnp-2006-correspondence-others.pdf

6879-delnp-2006-description (complete).pdf

6879-delnp-2006-drawings.pdf

6879-delnp-2006-form-1.pdf

6879-delnp-2006-form-18.pdf

6879-delnp-2006-form-2.pdf

6879-delnp-2006-Form-3-(04-04-2011).pdf

6879-delnp-2006-form-3.pdf

6879-delnp-2006-form-5.pdf

6879-delnp-2006-gpa.pdf

6879-delnp-2006-pct-search report.pdf

6879-DELNP-2006-Petition-137-(04-11-2011).pdf

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