JP6218363B2 - Hydrostatic drive system - Google Patents

Description

  The present invention is a hydrostatic drive system, and is provided with a pump capable of adjusting a pressure-feed volume for supplying a pressure medium to at least one consumer, and the pump-feed volume adjusting device of the pump uses a setting signal. In relation to the hydraulic return signal, which is controlled in the direction of pumping volume increase and detects the over-pumped volume flow of the pump, it is controlled in the direction of pumping volume decrease to obtain the return signal Therefore, the present invention relates to a type in which a circulating pressure compensator for generating a hydraulic return signal is provided at a return signal generation position.

  In this type of drive system, the pumping volume of the pump is adjusted to the volumetric flow demand required by the controlled consumer, so that the consumer is predetermined at the control valve with little energy loss. Can be driven by different movement speeds. Such drive systems are used to control hydraulic consumers in self-propelled work machines such as excavators or premises vehicles.

  In known load-sensing drive systems where the pump is operated in an open circuit and is provided with a corresponding control valve for controlling the consumer, the pumping volume of the pump is the maximum load pressure of the consumer being controlled. And it is adjusted by the adjustment pressure difference. When controlling the control valve or valves, the defined open cross section is adjusted in each control valve. The pump moves in the direction of increasing pumping volume until the regulated maximum load pressure of the controlled consumer increases the pump's pumping pressure by a regulated pressure differential above the controlled consumer's maximum load pressure. Let The pump thus supplies the volumetric flow demand required by the corresponding open cross section of the control valve from the controlled consumer.

  Based on the adjustment of the pumping volume of the pump in relation to the maximum load pressure of the consumer to be controlled, however, the action of the pumping volume adjustment is delayed in time and thus the introduction of movement by the control of the corresponding control valve and There is a considerable time delay between the start of exercise of the consumer. This is because the load pressure that controls the pump is only generated after the control valve has been switched to the open position. Such a delay is perceived by the operator as a slight dynamic behavior of the drive system.

  In order to avoid the above drawbacks, in the drive system of the type described at the beginning, the pumping volume adjusting device of the adjusting pump capable of adjusting the pumping amount is controlled in the direction of increasing the pumping volume by the setting signal. A hydraulic return signal acts to adjust the pump's pumping volume to perfectly match the desired pumping flow demand of the consumer to be controlled, and this return signal exceeds the pump's consumer demand. In association with this return signal, the pump volume controller is controlled in the direction of pump volume reduction. In order to generate a hydraulic return signal, a circulating pressure compensator is provided which is controlled by the pumping pressure of the pump and the load pressure of the consumer, this circulating pressure compensator being at the control edge a hydraulic return signal. Give birth. In this case, the circulation pressure compensator may be arranged in a branch line connecting the pressure feed line with the container, and at the return signal generation position formed as a through-flow position, on the downstream side of the circulation pressure compensator in the branch line. In a throttling device that is arranged and formed as a damming nozzle, a damming pressure (Staudruck) is generated as a hydraulic return signal.

  A drive system of the type mentioned at the outset is known on the basis of DE102008038381A1 and DE102008038382A1. In DE102008038381A1, the pump can control or adjust the pumping volume in an electrohydraulic manner. The hydraulic pressure return signal for loading the pumping volume control device in the direction of decreasing the pumping volume includes a circulating pressure compensator arranged in a branch pipe connecting the pump feeding pipe to the container, and a circulating pressure compensator of the circulating pressure compensator. It is generated in a throttling device arranged as a damming nozzle and arranged in the branch line on the downstream side.

  In order to control the pumping amount of the pump, DE 102008038381A1 is provided with a regulating pressure valve which controls the load due to the regulating pressure on the regulating piston device which is operatively connected to the pumping volume regulating device of the pump. The regulating pressure valve is formed as an electrically controllable pressure reducing valve, and this pressure reducing valve increases the pumping amount of the pump in the direction of decreasing the regulated pressure by an electric control signal forming a setting signal, and The hydraulic pressure return signal is operated in the direction of increasing the adjustment pressure for the purpose of reducing the pumping amount against the electric control signal. Due to the regulating pressure generated by the regulating pressure valve, the regulating piston device is loaded in the direction of reducing the pumping volume, so that the pumping volume of the pump can be adjusted perfectly to the pumping flow demand required by the consumer. .

  In DE102008038382A1, which does not require a regulating pressure valve to control the pumping volume adjusting device of the pump, the pumping volume of the pump is controlled or adjusted mechanically. The adjusting piston device, which is operatively connected to the pumping volume adjusting member of the pump, is always loaded in the direction of the pumping volume increase by a hydraulic adjusting pressure or spring as a setting signal. In the direction of reduced pumping, the adjusting piston device is loaded with a hydraulic return signal.

  In the drive system of the type mentioned at the outset, various embodiments of the pumping amount adjustment and various control embodiments of the pumping amount adjusting device, in turn, of various adjusting devices for adjusting the pumping amount of the pump. Embodiments are used, for example, electrohydraulic adjustment aspects such as in DE102008038381A1, or mechanical hydraulic adjustment aspects as in DE102008038382A1, in which various adjustment pressure levels are used. In this case, a high adjustment cost or effort is required to adapt the hydraulic return signal.

  Furthermore, in certain operating conditions, it is not desired to reduce the pumping amount of the pump with a hydraulic return signal. As such an operating state, for example, a case where the consumer exercises that the operator suddenly or vibrates is performed with quick and plural speed changes of the consumer. In the case of consumer motion as described above, a hydraulic return signal that detects the volume flow of an over-pumped pump exceeding the demand of the consumer and reduces the pumping volume of the pump. The dynamism or dynamic performance is reduced, which in turn reduces the dynamic performance of the drive system.

DE102008038381A1 DE102008038382A1

  Therefore, an object of the present invention is to provide a drive system that can eliminate the above-mentioned drawbacks in the drive system of the type described at the beginning.

  In order to solve this problem, in the configuration of the present invention, a pressure limiting device is disposed in a return signal line for guiding a hydraulic return signal and / or a shut-off device for the hydraulic return signal is provided. Is provided.

  Limiting the height of the hydraulic return signal in a simple manner and adjusting the selected control of the pumped volume regulator to the regulated pressure level in a simple manner by means of a pressure limiting device arranged in the return signal line It becomes possible. This makes it possible to easily adapt the hydraulic return signal to the pressure level of the control of the pumping volume adjusting device. As a result, the pumping amount control mode according to the present invention can be adapted to various control modes of the pumping amount adjusting device. And in a wide variety of embodiments of regulating devices having different regulating pressure levels, they can be easily and flexibly incorporated or used.

  The shut-off device according to the invention for the hydraulic return signal makes it possible to simply interrupt the hydraulic return signal that is generated in the circulating pressure compensator and reduces the pumping volume of the pump, and thus the hydraulic return signal. A decrease in the pumping amount of the pump based on the signal can be avoided. Such a shut-off device can therefore easily avoid an inconvenient reduction in pump pumping capacity by shutting off the hydraulic return signal for certain consumer movements, for example vibrations in the consumer, It is possible to improve the dynamic performance of the controlled consumer and thus the drive system dynamic performance in certain operating conditions.

  In a particularly advantageous embodiment of the invention, the shut-off device is formed by a shut-off valve arranged in a return signal line for conducting a hydraulic return signal. The shut-off valve in the return signal line can easily interrupt the hydraulic return signal generated in the circulating pressure compensator, which reduces the pumping volume of the pump, and thus the pump return signal due to the hydraulic return signal. The decrease in the pumping volume can be blocked.

  In an advantageous manner with regard to the simple construction, the shut-off valve has a connection position in which the return signal line leading to the pumping volume control device is opened and a shut-off position in which the return signal line is cut off. For example, such a two-position valve, which is a switching valve having a simple structure, can easily connect / cut off a hydraulic return signal for controlling the pumping amount of the pump.

  In another aspect of the present invention, at the shut-off position of the shut-off valve, the branch portion of the return signal conduit that leads to the pressure-feeding volume adjusting device is released to the container. The release signal of the adjusting device for the return signal can be easily released, so that the setting signal for adjusting the pumping amount of the pump becomes decisive, so that the pump is loaded in the direction of increasing the pumping volume and set A pre-adjusted pumping stream corresponding to the signal is supplied.

  In another advantageous embodiment of the invention, the shut-off valve can be operated between a connection position and a shut-off position using an operating device, in particular a switching magnet. The shut-off valve can be operated, for example, hydraulic, electrohydraulic or direct electric. The direct electrical operation of the shut-off valve by the switching magnet makes it possible to operate the shut-off valve easily and inexpensively.

  In another aspect of the invention, the return signal line is released into the container using a damming nozzle. Such a damming nozzle allows the volume flow to flow out of the return signal line into the container, and at this time, the selection of the damming nozzle can change and adjust the volume flow flowing out of the container. The pressure gradient of the hydraulic return signal in the return signal line can be influenced.

  In a particularly advantageous embodiment of the invention, the pump is pre-adjusted to a predetermined pumping volume, in particular a maximum pumping volume, using a setting signal in the signal line. With this configuration, the pump is adjusted to the pumping volume defined by the setting signal, preferably the maximum pumping volume, by means of a corresponding constant or non-changeable setting signal, whereby the pump is set to a predetermined pumping volume. Stream, preferably a maximum pumping stream. If the consumer does not completely receive the pumping flow supplied by the pump, a hydraulic return signal is generated in the circulating pressure compensator, which reduces the pump pumping volume by reducing the pump pumping volume. Is matched to consumer demand, and excess volume flow not received by the consumer is limited and reduced.

  If the pump is pre-adjusted to a predetermined pumping volume using a setting signal in the signal line, the setting signal can be adjusted using a setting valve, in particular using an electrically adjustable signal. This is particularly advantageous. In this way, the pumping volume adjusted by the setting signal sets the volume flow of the pump and limits the volume flow. By changing and adjusting the setting signal, the volume flow limit of the pump can be easily adjusted and matched to the drive output of the drive machine that drives the pump, for example.

  Other advantages and details of the invention are described in detail below for the illustrated embodiments.

1 is a circuit diagram showing a first embodiment of a hydrostatic drive system according to the present invention. FIG. It is a circuit diagram which shows 2nd Embodiment of the hydrostatic drive system by this invention. It is a circuit diagram which shows 3rd Embodiment of the hydrostatic drive system by this invention.

  FIG. 1 shows a load sensing adjustable drive system 1 according to the invention. The drive system 1 is used, for example, in a self-propelled work machine, such as an excavator or a yard transport vehicle.

  The drive system 1 has a pump 2 with adjustable pumping volume, which is operated in an open circuit and is drivingly coupled to a drive machine 3 such as an internal combustion engine for driving. The pump 2 is connected to the container 5 via the pipe line 4 on the suction side, and pumps the pressure medium through the pressure feed line 6.

  In order to control one or a plurality of consumer machines V, one respective control valve 7 is provided which is formed as a direction switching valve having a throttling action at an intermediate position.

  The control valve 7 is connected to the pressure supply line 6, the container line 9, and the pressure medium lines 8 a and 8 b leading to the consumer V, respectively. When the control valve 7 is operated, the control valve 7 controls the connection between the pressure medium pipes 8a and 8b leading to the consumer V and the pressure feed pipe 6 and the container pipe 9 at the corresponding control positions 7a and 7b. In connection with the control signal in the lines 7c, 7d, the defined open cross section from the pressure line 6 to the pressure medium line 8a; 8b is opened. The control valve 7 may be provided with a pressure compensator (Druckwaage) (not shown) for controlling the movement speed of the consumer V independently of the load pressure.

  In order to control the control valve 7, an electronic control device 80 is provided, and this electronic control device 80 is operatively connected to a setting device (Vorgabeeinrichtung) 81, which is a joystick, for example, on the input side. For its operation, the control valve 7 has a corresponding electrical operating device, such as a magnet, which is connected to the electronic control device 80 on the output side. Instead of an electric operation device, it is also possible to operate the control valve 7 by hydraulic pressure. In this case, in order to generate a control pressure that presses the control valve 7, an electrically controllable control pressure valve is provided. These control pressure valves are connected to the electronic control unit 80 on the output side.

  The pump 2 is configured as a pump capable of adjusting the pumping amount, and the pumping volume of the pump can be adjusted by using the pumping volume adjusting device 10. For this purpose, an adjustment piston device 11 is provided, this adjustment piston device 11 having an adjustment piston 13 arranged in an adjustment cylinder 12, this adjustment piston 13 being a pumping volume of the pumping volume adjusting device 10. The pumping volume adjusting member S is, for example, a swash plate capable of adjusting the inclination of a pump formed as an axial piston pump in the swash plate structure type.

  The adjusting piston device 11 has an adjusting pressure chamber 14, which presses the pumping volume adjusting device 10 in the direction of the maximum pumping volume. The adjusting piston device 11 has another adjusting pressure chamber 15 that presses the pumping volume adjusting device 10 in the direction of the minimum pumping volume. The adjustment piston 13 can be pressed in the direction of the maximum pumping volume by using a spring F disposed in the adjustment pressure chamber 14. In the direction of the minimum pumping volume, the adjusting piston 13 can be pressed by the adjusting pressure in the adjusting pressure chamber 15 of the adjusting piston device 11. For this purpose, the regulating pressure chamber 15 is connected to a regulating pressure line 16.

  The illustrated pumping volume adjusting device 10 can be controlled in an electrohydraulic manner. For this purpose, a regulating pressure valve 20 that can be operated electrically, for example, a pressure reducing valve, is arranged in the regulating pressure line 16. The control pressure valve 20 is connected on the input side to a control pressure source 17 of the drive system 1, for example, a supply pump or a control pressure pump. However, it is also possible to connect the input side of the regulating pressure valve 20 to the pumping line 6 of the pump. The adjusting pressure chamber 14 provided with the spring F of the adjusting piston device 11 is released toward the container 5.

  The electronic control device 80 is further connected on the output side with a regulating pressure valve 20 formed as a regulating pressure valve that can be electrically controlled. In this case, the electronic control device 80 forms a setting device by corresponding control of the control pressure valve 20 (in this case, a corresponding control pressure is generated in the control pressure line 16). The volume adjusting device 10 is loaded in the direction of increasing the pumping volume, for example in connection with a control signal for operating the control valve 7 and thus in connection with a control signal for operating the consumer V, thereby The pump 2 supplies a predetermined pumping amount and a pre-adjusted pumping flow under the control of the adjusting pressure valve 20.

  The pump 2 is loaded in a direction to reduce the pumping volume by a hydraulic return signal that is detected from the pump 2 and detects an excessive volume flow exceeding the demand of the consumer V. In order to generate a hydraulic return signal, a circulation pressure compensator (Umlaufdruckwaage) 31 is arranged in the branch line 30 branched from the pressure feed line 6, and this circulation pressure compensator 31 is branched on the input side. Connected to the conduit 30 and on the output side is connected to a return signal conduit 32 for guiding a hydraulic return signal.

  The circulation pressure compensator 31 has a blocking position 31a for cutting off the connection between the branch pipe 30 and the return signal pipe 32, and a through-flow position 31b for connecting the branch pipe 30 and the return signal pipe 32. The through-flow position 31b forms a return signal generation position 31b. The circulating pressure compensator 31 is pressed toward the shut-off position 31a by the maximum load pressure of the controlled consumer V and the spring device 33, and is pressed toward the return signal generation position 31b by the pumping pressure of the pump 2. Has been. For this purpose, a load pressure transmission line 34 for guiding the maximum load pressure of the consumer V to be controlled is connected to the control surface of the circulating pressure compensator 31 that acts toward the shut-off position 31a. A control line 35 branched from the pressure feed line 6 or the branch line 30 is connected to a control surface of the circulation pressure compensator 31 that acts toward the return signal generation position 31b. The circulation pressure compensator 31 is advantageously formed as a control valve having a throttling action in the intermediate position.

  In the pressure-feed volume adjusting device 10 of FIG. 1, a return signal line 32 for guiding a hydraulic return signal is led to supply a pressure medium to the control pressure valve 20 of the pressure-feed volume adjusting device 10. The hydraulic return signal acts against the electrical control signal in the regulating pressure valve 20 to increase the regulating pressure in the regulating pressure line 16, thereby causing the pumping volume adjusting device 10 to resist the spring F and the pump. In order to reduce the pumping volume in relation to the excessively pumped volume flow, the pumped volume of the pump 2 is pushed towards the minimum pumping volume, to the volume flow demand required by the controlled consumer V And adjusted. In connection with the hydraulic return signal, the pumping volume control device 10 is thereby controlled in a direction to reduce the pumping amount of the pump 2, so that the pumping flow pumped by the pump 2 is controlled by the controlled consumer V. It can be perfectly adjusted to the required demand.

  The return signal line 32 can be released to the container 5 via a damming nozzle (Stauduese) 60. For example, a damming nozzle 60 that is a throttle is disposed in a branch line 61 that leads from the return signal line 32 to the container 5. The blocking nozzle 60 can be used to influence the pressure gradient of the hydraulic return signal produced by the volume flow flowing out of the return signal line 32 into the container 5.

  In the drive system 1 of FIG. 1, according to the present invention, a pressure limiting device 50 is disposed in the return signal line 32 led to the pumping volume adjusting device 10, and the return signal line 32 is provided by the pressure limiting device 50. The height of the hydraulic return signal guided inside can be limited and possibly adjusted. The pressure limiting device 50 is formed as a pressure limiting valve, and is arranged in a branch line 51 branched from the return signal line 32 and leading to the container 5.

  Furthermore, according to the invention in FIG. 1, a shut-off device 70 is provided for a hydraulic return signal that reduces the pumping amount of the pump 2.

  In the illustrated embodiment, the shut-off device 70 is formed by a shut-off valve 71 arranged in the return signal line 32 leading to the regulating pressure valve 20, and this shut-off valve 71 has a connection position 71a. In 71a, the return signal line 32 is opened. The shut-off valve 71 further has a shut-off position 71b where the return signal conduit 32 is shut off. In order to cancel the load of the control pressure valve 20 due to the hydraulic return signal at the shut-off position 71b, and thus to stop the reduction in the pumping amount of the pump 2 caused by the hydraulic return signal, the shut-off valve 71 is The branch part of the return signal line 32 that is connected to the pressure release line 72 that leads to the container 5 and that leads to the regulating pressure valve 20 is connected to the pressure release line 72 at this blocking position 71b. The pressure is released to the container 5. Further, at the blocking position 71b, the branch portion of the return signal line 32 from the circulating pressure compensator 31 is blocked. At the connection position 71a, the pressure release pipe 72 is blocked.

  The shut-off valve 71 is formed as a switching valve in the illustrated embodiment. The shutoff valve 71 can be operated between the connection position 71a and the shutoff position 71b by using the operating device 75. In the illustrated embodiment, the shut-off valve 71 can be operated electrically. In this case, the operating device 75 is provided with a switching magnet. The operating device 75 is preferably operatively connected to the electronic control device 80 for control purposes.

  The pressure limiting device 50 shown in FIG. 1 is disposed on the downstream side of the shut-off device 70, and thus between the shut-off device 70 and the regulating pressure valve 20.

  FIG. 2 shows a second embodiment of the present invention. In the embodiment of FIG. 2, the same members are denoted by the same reference numerals.

  The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in the configuration and control of a pressure-feed volume adjusting device 10 formed in a mechanical hydraulic manner as shown.

  The adjusting piston 13 of the adjusting piston device 11 can always be pressed in the direction of increasing the pumping volume using a setting device formed as a spring F.

  In addition to or as an alternative to the spring F, the adjusting piston 13 of the adjusting piston device 11 may always be pressed in the direction of increasing the pumping volume by the adjusting pressure forming the setting device. For this purpose, an adjustment pressure line 16 is connected to the control pressure chamber 14 of the adjustment piston device 11 in which the spring F is similarly arranged and acts in the direction of increasing the pumping volume. Without the intervention of a regulating pressure valve, it may be connected to a control pressure source 17, for example the control pressure pump or supply pump of the drive system 1 and / or the pressure feed line 6 of the pump 2. As in the illustrated embodiment, when the regulating pressure line 16 is connected to the pumping line 6 and the control pressure source 17 of the pump 2, a selection valve device 18 formed as a shuttle valve, for example, may be provided. The selection valve device 18 is connected to the control pressure source 17 and the branch pipe branching from the pressure feed pipe 6 of the pump 2 on the input side, and is connected to the control pressure pipe 16 on the output side. The pump 2 in FIG. 2 is adjusted in advance to the maximum pumping amount by the spring F or the adjusting pressure in the adjusting pressure chamber 14.

  In the pumping volume adjusting device 10 of FIG. 2, the return signal line 32 that guides the hydraulic return signal generated in the circulating pressure compensator 31 is a control that acts in the direction of reducing the pumping volume of the adjusting piston device 11. It is led to the pressure chamber 15.

  Similar to the embodiment of FIG. 1, in FIG. 2, the return signal line 32 can be released to the container 5 via a damming nozzle 60 arranged in the branch line 61 that leads to the container 5.

  Further, in FIG. 2, corresponding to FIG. 1, a shut-off device 70 for a hydraulic return signal that reduces the pumping amount of the pump 2 is provided, and this shut-off device 70 leads to the control pressure chamber 15. The pump 2 which is arranged in the return signal line 32 and eliminates the load on the adjustment pressure chamber 15 of the adjustment piston device 11 due to the hydraulic return signal at the shut-off position 71b, and consequently is generated by the hydraulic return signal. The reduction of the pumping amount can be achieved.

  Corresponding to FIG. 1, a pressure limiting device 50 is arranged in the return signal line 32, and the pressure limiting device 50 limits the height of the hydraulic return signal guided in the return signal line 32. Yes, and possibly adjustable. In FIG. 2, the pressure limiting device 50 is disposed on the upstream side of the shut-off device 70, and as a result, is disposed between the shut-off device 70 and the circulation pressure compensator 31.

  FIG. 3 shows still another embodiment of the present invention, in which the same members are denoted by the same reference numerals.

  The embodiment of FIG. 3 differs from the embodiment of FIGS. 1 and 2 in the configuration and control of the pumping volume adjusting device 10 formed with the adjusting pressure valve 20 that is pilot-controlled as shown in FIG. is there.

  In FIG. 3, the adjustment pressure chamber 14 of the adjustment piston device 11 is connected to an adjustment pressure line 16, and the adjustment pressure line 16 is formed by using, for example, two shut-off valves that are check valves. 18 is connected to the pressure feed line 6 and / or the control pressure source 17 of the pump 2. In addition to or as an alternative to the load of the regulating pressure chamber 14 through the regulating pressure line 16, i.e. the supply of the pressure medium to the regulating pressure chamber 14, a spring device may be arranged in the regulating pressure chamber 14. Presses the pumping volume adjusting device 10 in the direction of the maximum pumping volume.

  The adjustment pressure valve 20 for controlling the load of the adjustment pressure chamber 15 of the adjustment piston device 11, that is, the supply of the pressure medium to the adjustment pressure chamber 15, is connected to the adjustment pressure line 16 on the input side in FIG.

  The regulating pressure valve 20 has a first control position 20a that acts in the direction of decreasing the pumping volume, and a second control position 20b that acts in the direction of increasing the pumping volume. For this purpose, the control pressure valve 20 is connected to a pressure relief line 21 that leads to the container 5. The control pressure chamber 15 is connected to the control pressure line 16 at the first control position 20a. When the adjustment pressure in the adjustment pressure chambers 14 and 15 is the same at the first control position 20a, the adjustment piston device 11 receives the pressure receiving areas of the adjustment pressure chambers 14 and 15 of the adjustment piston device 11 formed as a stepped piston. Based on the difference, the adjustment pressure in the adjustment pressure chamber 15 is pressed to the right in the direction of decreasing the pumping volume as viewed in FIG. The adjusting pressure chamber 15 is connected to the container 5 at the second control position 20b. Due to the adjustment pressure in the control pressure chamber 14, this causes the adjustment piston device 11 to be pressed to the left in the second control position 20b in the direction of increasing the pumping volume in FIG. The regulating pressure valve 20 is formed as a longitudinal slide valve having a throttling action at an intermediate position, and may include a blocking position 20c between the control positions 20a and 20b.

  The control slider of the adjustment pressure valve 20 is pressed toward the first control position 20 a by using the spring device 22. In order to operate the control slider of the regulating pressure valve 20 toward the second control position 20b, a control surface 23 is provided, and this control surface 23 is connected to a pilot control line 25. The regulating pressure valve 20 is formed as a regulating valve in the illustrated embodiment, and the control slider is arranged in a movable sleeve which is connected to the regulating piston device 11 or the pressure feed via a mechanical coupling device 26. The volume adjusting device 10 is operatively coupled.

  The pump 2 of FIG. 3 can be loaded in the direction of increasing the pumping amount using a hydraulic setting signal (Vorgabesignal). For this purpose, a signal line 27 for guiding the setting signal can be connected to the pilot control line 25. In the embodiment shown, the signal line 27 is connected to the regulating pressure line 16 via an electrically controllable setting valve 28. In the illustrated embodiment, the setting valve 28 is formed by a pressure regulating valve that can be electrically adjusted using a proportional magnet 29, and from this pressure regulating valve 16 to a signal line 27. Accordingly, a corresponding set pressure can be generated as a hydraulic set signal. Depending on the height of the setting signal, the regulated pumping volume of the pump 2 can be set by corresponding control of the regulating pressure valve 20, so that the pump 2 pumps a predetermined volume flow as a volume flow limit value. The setting signal advantageously has the maximum pumping volume when the pump 2 is present in the pilot control line 25, i.e. when the regulating pressure valve 20 is pressed towards the second control position 20b. It is configured to be adjusted in advance.

  In FIG. 3, the control pressure valve 20 is formed as a control pressure valve 20 that is pilot-controlled. In this case, a pilot control valve 40 that is controlled by a hydraulic return signal in the return signal line 32 is provided. The load or press of the control surface 23 of the control pressure valve 20 by the valve 40, and hence the load or press of the control pressure valve 20 toward the second control position 20b is determined by a setting signal for reducing the pumping amount of the pump 2. In connection with the hydraulic return signal, it can be over-controlled.

  For this purpose, the pilot control valve 40 is connected to a signal line 27 that guides the setting signal, a pilot control line 25 that leads to the control surface 23 of the regulating pressure valve 20, and a pressure relief line 41 that leads to the container 5. The pilot control valve 40 has a first control position 40a, and the signal line 27 is connected to the pilot control line 25 in the first control position 40a. In the first control position 40a, the pressure release line 41 is further blocked. Further, the pilot control valve 40 has a second control position 40 b where the pilot control line 25 is connected to the pressure relief line 21. The signal line 27 is cut off at the second control position 40b. In the illustrated embodiment, the pilot control valve 40 is formed as a control valve having a throttling action at an intermediate position, for example a longitudinal slide valve.

  The pilot control valve 40 is pressed in the direction of the first control position 40a using the spring device 42. Depending on the hydraulic return signal guided in the return signal line 32, the pilot control valve 40 is pressed in the direction of the second control position 40b. Has been.

  The pump 2 in which the pumping amount is pilot controlled in an electrohydraulic manner according to the invention shown in FIG. 3 is generated in the signal line 27 by the setting valve 28 during the corresponding electric control of the setting valve 28. In order to obtain the maximum swivel angle of the swash plate of the pump formed as an axial piston pump, for example, in the swash plate structure type, in advance by the hydraulic setting signal to the prescribed pumping amount, preferably to the maximum pumping amount. Regulated, this setting signal presses the regulating pressure valve 20 toward the second control position 20b when the pilot control valve 40 occupies the first control position 40a. At this time, if the pumping flow supplied from the pump 2 is not received by the consumer V of the drive system 1, the circulating pressure compensator 31 resists the force of the spring 33 by the pumping pressure of the pump 2 and is singular. Alternatively, in the case of a plurality of controlled consumers V, the load signal is pressed in the direction of the return signal generation position 31b against the load pressure in the load pressure transmission line 34, and the return signal line 32 is pressed at the return signal generation position 31b. A hydraulic return signal is generated at. The pilot control valve 40 controlled by the hydraulic pressure return signal is pressed toward the second control position 40b by the generated hydraulic pressure return signal, and at this time, the pilot control pipe leading to the pressure release line 41 is obtained. Via an additional signal path in path 25, the setting signal for loading the regulating pressure valve 20 towards its second control position at its control surface 23 is released and thus reduced, so that the regulating pressure valve 20 is spring-loaded. The device 22 is pressed toward the first control position 20a, and the pumping volume adjusting device 10 is pressed in the direction of decreasing the pumping amount at the first control position 20a, for example, the swash plate is turned back. As a result, the pump 2 that has been adjusted to the pumping amount that has been adjusted in advance by the setting signal in the signal line 27 by the pilot control valve 40 that is controlled in relation to the hydraulic return signal is pumped by the hydraulic return signal. Can be over-controlled for reduction. The pumped volume flow supplied from the pump 2 pre-adjusted to a predetermined pumping amount can thereby be weakened and reduced in connection with the pumped flow demand of the consumer V. And this can reduce and limit the excess volume flow that exceeds the demand of the consumer V and is pumped by the pump 2.

  Similar to the embodiment of FIGS. 1 and 2, in FIG. 3, the return signal line 32 can also be released to the container 5 using a damming nozzle 60 disposed in the branch line 61 leading to the container 5. .

  Further, in FIG. 3, corresponding to FIGS. 1 and 2, a shut-off device 70 for a hydraulic return signal for reducing the pumping volume of the pump 2 is provided, and this shut-off device 70 is connected to the pilot control valve 40. At the shut-off position 71b, the control of the pilot control valve 40 by the hydraulic return signal is stopped, that is, the pressure medium that has been pressing the pilot control valve 40 is released in the pressure release pipe. The pressure can be released to the container 5 through the path 72. In this case, the pilot control valve 40 is pressed toward the first control position 40a by the spring device 42, so that the return turning of the pump 2 caused by the hydraulic return signal is interrupted.

  In accordance with FIGS. 1 and 2, a pressure limiting device 50 is provided in the return signal line 32, and the pressure limiting device 50 is used to transmit a hydraulic return signal guided in the return signal line 32. The height can be limited and, in some cases, adjustable.

  In FIG. 3, the electronic control device for controlling the setting valve 28 and the shutoff device 70 or the control valve 7 is not shown.

  The present invention has a series of advantages.

  With the pressure limiting device 50 disposed in the return signal line 32 and the damming nozzle 60 disposed in the return signal line 32, the pressure feed amount control device according to the present invention has various adjustment levels. The various control forms and configuration forms of the pumping amount adjusting device 10 can be incorporated flexibly and easily. The pressure level of the hydraulic return signal in the return signal line 32 and the pressure level of the adjusting pressure in the adjusting pressure line 16 are possible in this case until the maximum pump pressure is reached.

  Improved dynamics of the drive system 1 by using the shut-off valve 71 in certain operating conditions by operating on the shut-off position 71b and thus by interrupting the hydraulic return signal that causes a reduction in the pump 2 pumping volume. Performance can be obtained. By preventing the pump 2 from reducing the pumping amount when the shut-off valve 71 occupies the shut-off position 71b, significantly improved dynamic performance of the drive system 1 can be obtained during certain consumer movements. . Such a consumer motion is, for example, a rapid and multiple speed change of the consumer V, and the occurrence of vibration in the consumer V is desired due to such a speed change. If the work machine formed as an excavator is equipped with a drive system according to the present invention, such vibrations may be desired in the consumer machine V that controls the excavator, and the excavator is adjusted by this vibration. Can be emptied.

  In the context of the pressure limiting device 50, the damming nozzle 60 and / or the shut-off device 70, this gives rise to advantages with regard to the simple adaptability of the drive system 1 and the slight energy consumption of the drive system 1.

  DESCRIPTION OF SYMBOLS 1 Drive system, 2 Pump, 3 Drive machine, 4 Pipe line, 5 Container, 6 Pressure feed line, 7 Control valve, 7a, 7b Control position, 7c, 7d Control line, 8a, 8b Pressure medium pipe, 9 Container pipe 10 control volume control device, 11 control piston device, 12 control cylinder, 13 control piston, 14, 15 control pressure chamber, 16 control pressure line, 17 control pressure source, 18 selection valve device, 20 control pressure valve, 20a first Control position, 20b second control position, 20c cutoff position, 21 pressure relief line, 22 spring device, 23 control surface, 25 pilot control line, 26 coupling device, 27 signal line, 28 setting valve, 29 proportional magnet 30 branch pipe line, 31 circulating pressure compensator, 31a cutoff position, 31b return signal generation position, 32 Return signal line, 33 spring device, 34 load pressure transmission line, 35 control line, 40 pilot control valve, 40a first control position, 40b second control position, 41 pressure relief line, 42 spring device, 50 Pressure limiting device, 51 branch pipe, 60 damming nozzle, 61 branch pipe, 70 shutoff device, 71 shutoff valve, 71a connection position, 71b shutoff position, 72 pressure relief pipe, 75 operation device, 80 electronic control device, 81 Setting device, F spring, S pumping volume adjustment member, V consumer

Claims (7)

A hydrostatic drive system is provided with a pump capable of adjusting the pressure-feed volume for supplying a pressure medium to at least one consumer, and the pump-feed volume adjusting device of the pump uses a setting signal to increase the pump-feed volume. In relation to the hydraulic return signal, which is controlled in the direction of the pump and to detect the over-pumped volume flow of the pump, and is controlled in the direction of pumping volume reduction, the return to obtain the return signal In the type in which a circulating pressure compensator for generating a hydraulic return signal is provided at the signal generation position, a return signal line (32) for guiding the hydraulic return signal is provided for the hydraulic return signal. A shut-off device (70) is provided, and the shut-off device (70) is formed by a shut-off valve (71) disposed in a return signal line (32) for guiding a hydraulic return signal. The valve (71) is being returned Shi signal line (32) is open, the connection position to reduce the pumping volume of the pump and (71a), the return signal line (32) is interrupted, the delivery amount of the pump The pressure-feeding volume adjusting device (10) is electrically controlled by an electrically operable adjusting pressure valve (20) connected to a control pressure source (17). Hydrostatic drive system, characterized in that it is hydraulically controllable and the return signal line (32) supplies pressure medium to the regulating pressure valve (20) .   The hydrostatic drive system according to claim 1, wherein a pressure limiting device (50) is arranged in the return signal line (32) for guiding the hydraulic return signal.   2. The branch portion of the return signal pipe line (32) leading to the pressure feeding volume adjusting device (10) is released to the container (5) at the shut-off position (71 b) of the shut-off valve (71). 2. The hydrostatic drive system according to 2.   The hydrostatic valve according to any one of claims 1 to 3, wherein the shut-off valve (71) is operable between the connection position (71a) and the shut-off position (71b) using the operating device (75). Drive system.   5. The hydrostatic drive system according to claim 1, wherein the return signal line (32) is released to the container (5) by using a damming nozzle (60).   The hydrostatic drive system according to any one of claims 1 to 5, wherein the pump (2) is preliminarily adjusted to a predetermined pumping volume using a setting signal in the signal line.   7. The hydrostatic drive system according to claim 1, wherein the setting signal is adjustable using a setting valve (28).

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