JP2009085398A - Hydraulic drive device for work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic drive device for a work machine capable of reducing line resistance when returning the minimum flow amount from a hydraulic pump to a tank during the time when an actuator is not operated, and capable of improving suction performance of other hydraulic pump. <P>SOLUTION: The hydraulic drive device for work machine is provided in a hydraulic shovel having variable capacity type hydraulic pumps 10 and 11, a boom cylinder 7 to be driven by the pressure oil of the hydraulic pump 10 and an arm cylinder 8 to be driven by the pressure oil of the hydraulic pump 11, and has a first communication line 19 capable of supplying the pressure oil of the hydraulic pump 10 to a suction side of the hydraulic pump 11, a second communication line 20 capable of supplying the pressure oil of the hydraulic pump 11 to a suction side of the hydraulic pump 10, a first selector valve 21 provided in the first communication line 19 and a second selector valve 22 provided in the second communication line 20. When the boom cylinder 7 is not being operated, the first selector valve 21 is operated to be opened so as to open the first communication line 19, and when the arm cylinder 8 is not being operated, the second selector valve 22 is operated to be closed to open the first communication line 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic drive device for a work machine that is provided in a work machine such as a hydraulic excavator and includes a plurality of actuators and a plurality of hydraulic pumps that supply pressure oil that drives the actuators.

  There exists a thing shown by patent document 1 as this type of prior art. This prior art is provided in a work machine such as an earthwork vehicle, and includes a plurality of hydraulic pumps, a plurality of actuators such as a hydraulic cylinder device and a power cylinder driven by pressure oil discharged from these hydraulic pumps, and a hydraulic pump. And a directional control valve such as a main valve and a steering valve for controlling the flow of pressure oil supplied to each of the actuators.

In this prior art, when the hydraulic cylinder device is not operated when the earthwork vehicle is running, that is, when the actuator is not operated, the low pressure unload valve is operated and the operation discharged from the main pump, that is, the hydraulic pump. The entire amount of oil is returned to the tank.
Japanese Patent No. 3217248

  In the above-described prior art, when the actuator is not operated, a predetermined minimum flow rate is returned from the hydraulic pump to the tank via the low pressure unload valve. At this time, the low pressure unload valve is set. A relatively large line resistance corresponding to the pressure is generated, and a pump driving torque corresponding to the large line resistance is required. For this reason, there is a problem that energy loss increases. In this prior art, no special consideration is given to the suction performance of the hydraulic pump. When the suction performance of the hydraulic pump is deteriorated, there is a problem that the durability of the hydraulic pump is deteriorated by cavitation and the life of the hydraulic pump is shortened.

  The present invention has been made from the above-described prior art, and its purpose is to reduce the pipe resistance when returning a predetermined minimum flow rate from a predetermined hydraulic pump to the tank when the actuator is not operated. Another object of the present invention is to provide a hydraulic drive device for a work machine that can improve the suction performance of another hydraulic pump different from a predetermined hydraulic pump.

  In order to achieve this object, the present invention includes a plurality of hydraulic pumps, a plurality of actuators driven by pressure oil discharged from these hydraulic pumps, and a plurality of actuators from the hydraulic pumps. And a plurality of directional control valves for controlling the flow of pressure oil supplied to the hydraulic drive device, wherein the pressure oil discharged from a predetermined hydraulic pump among the plurality of hydraulic pumps is supplied to the predetermined hydraulic pump. A connecting pipe that can be supplied to the suction side of another hydraulic pump different from the hydraulic pump of the above, and a predetermined one of the actuators provided in the connecting pipe and operated by pressure oil discharged from the predetermined hydraulic pump An open / close valve that opens the communication line when the actuator stops operating and closes the communication line when the predetermined actuator operates. It is characterized in that was.

  In the present invention configured as described above, when the predetermined actuator that is operated by the pressure oil discharged from the predetermined hydraulic pump is operated, that is, when the operation is performed, the communication conduit is closed by the closing operation of the on-off valve. Thereby, the pressure oil from the predetermined hydraulic pump is supplied to the predetermined actuator via the corresponding directional control valve, and a desired work can be performed through the operation of the predetermined actuator.

  Further, when the operation of the predetermined actuator is stopped, that is, when it is not operated, the on-off valve is opened and the communication line is opened, and a predetermined minimum flow rate from the predetermined hydraulic pump is set to other values via this connection line. Supplied to the suction side of the hydraulic pump. At this time, since the connecting pipe is connected to the suction side of another hydraulic pump, the pressure is as low as the tank pressure, and the pipe resistance of the connecting pipe can be reduced. Thereby, the drive torque of a predetermined hydraulic pump can be suppressed small. Further, as described above, when the predetermined actuator is not operated, the minimum flow rate from the predetermined hydraulic pump is supplied to the suction side of the other hydraulic pump so that the suction performance of the other hydraulic pump is improved. Can be made. Thereby, the load of the other hydraulic pump can be reduced, and the excellent durability of the other hydraulic pump can be secured.

  Further, the present invention is the above invention, wherein the plurality of hydraulic pumps include a first hydraulic pump and a second hydraulic pump, and the communication conduit is discharged from the first hydraulic pump which is the predetermined hydraulic pump. A first connecting pipe that can supply the pressurized oil to the suction side of the second hydraulic pump that is the other hydraulic pump, and the pressure oil of the second hydraulic pump that is the predetermined hydraulic pump. A second communication pipe that can be supplied to the suction side of the first hydraulic pump, which is a hydraulic pump, wherein the on-off valve is a first on-off valve provided in the first communication pipe, and the second communication pipe. It consists of the 2nd on-off valve provided in the path.

  In the present invention configured as described above, when the predetermined actuator that is operated by the pressure oil discharged from the first hydraulic pump is not operated, the first on-off valve is opened to open the first communication pipe. A minimum flow rate is supplied from the first hydraulic pump to the suction side of the second hydraulic pump via the connecting pipe. As a result, the driving torque of the first hydraulic pump can be kept small, and the suction performance of the second hydraulic pump can be improved.

  Conversely, when the predetermined actuator that is operated by the pressure oil discharged from the second hydraulic pump is not operated, the second on-off valve opens to open the second connection line, and the second connection line is opened. Thus, the minimum flow rate is supplied from the second hydraulic pump to the suction side of the first hydraulic pump. As a result, the driving torque of the second hydraulic pump can be kept small, and the suction performance of the first hydraulic pump can be improved.

  When the non-operation of the predetermined actuator operated by the pressure oil discharged from the first hydraulic pump and the non-operation of the predetermined actuator operated by the pressure oil discharged from the second hydraulic pump are performed simultaneously, the above-described operation Is implemented in combination.

  When the predetermined actuator operated by the pressure oil discharged from the first hydraulic pump is operated, the first connecting pipe is closed by the closing operation of the first on-off valve, and the pressure oil from the first hydraulic pump corresponds. It is supplied to a predetermined actuator via a directional control valve, and a desired operation can be performed by operating the predetermined actuator. Similarly, when a predetermined actuator operated by the pressure oil discharged from the second hydraulic pump is operated, the second connecting pipe is closed by the closing operation of the second on-off valve, and the pressure oil from the second hydraulic pump corresponds. It is supplied to a predetermined actuator via a directional control valve, and a desired operation can be performed by operating the predetermined actuator.

  The present invention is characterized in that, in the above invention, the on-off valve is arranged at a connection point between the discharge line of the predetermined hydraulic pump and the communication line.

  In the present invention configured as described above, when the predetermined actuator operated by the pressure oil discharged from the predetermined hydraulic pump is not operated, the minimum flow rate from the predetermined hydraulic pump is reduced by the opening operation of the on-off valve. It is immediately supplied to the suction side of another hydraulic pump via a discharge line, an on-off valve, and a communication line. Thereby, the pressure oil of a predetermined hydraulic pump can be rapidly supplied to the suction side of another hydraulic pump.

  Further, the present invention is the above invention, wherein the plurality of hydraulic pumps include a first hydraulic pump and a second hydraulic pump, and the communication pipe line is one of the first hydraulic pump and the second hydraulic pump. One connecting conduit capable of supplying pressure oil supplied from one predetermined hydraulic pump to the suction side of the other hydraulic pump as the other of the first hydraulic pump and the second hydraulic pump And the on-off valve is composed of one on-off valve provided in the one communication line.

  In the present invention configured as above, the on-off valve opens when the predetermined actuator that is operated by the pressure oil discharged from the predetermined hydraulic pump that is one of the first hydraulic pump and the second hydraulic pump is not operated. Then, the communication line is opened, and the predetermined minimum flow rate from the predetermined hydraulic pump through this communication line is sucked in the other hydraulic pump which is the other of the first hydraulic pump and the second hydraulic pump. Supplied to the side. When operating a predetermined actuator that is operated by pressure oil discharged from a predetermined hydraulic pump that is one of the first hydraulic pump and the second hydraulic pump, the on-off valve is closed to close the communication line, The pressure oil from the hydraulic pump is supplied to a predetermined actuator via the corresponding directional control valve.

  Further, the present invention is the above invention, wherein the plurality of hydraulic pumps include a first hydraulic pump, a second hydraulic pump, and a third hydraulic pump, and the communication conduit is discharged from the first hydraulic pump. A first connection pipe capable of supplying pressure oil to the suction side of the third hydraulic pump, and a second connection pipe capable of supplying pressure oil discharged from the second hydraulic pump to the suction side of the third hydraulic pump. And the on-off valve is composed of a first on-off valve provided in the first communication pipe and a second on-off valve provided in the second communication pipe.

  In the present invention configured as described above, when the predetermined actuator that is operated by the pressure oil discharged from the first hydraulic pump is not operated, the first on-off valve is opened and the first connecting pipe is opened. A minimum flow rate is supplied from the first hydraulic pump to the suction side of the third hydraulic pump via one communication line. As a result, the driving torque of the first hydraulic pump can be kept small, and the suction performance of the third hydraulic pump can be improved.

  Further, when the predetermined actuator that is operated by the pressure oil discharged from the second hydraulic pump is not operated, the second on-off valve is opened to open the second connection line, and the second connection line is opened through the second connection line. A minimum flow rate is supplied from the second hydraulic pump to the suction side of the third hydraulic pump. As a result, the driving torque of the second hydraulic pump can be kept small, and the suction performance of the third hydraulic pump can be improved.

  When the non-operation of the predetermined actuator operated by the pressure oil discharged from the first hydraulic pump and the non-operation of the predetermined actuator operated by the pressure oil discharged from the second hydraulic pump are performed simultaneously, the above-described operation Is implemented in combination.

  When the predetermined actuator operated by the pressure oil discharged from the first hydraulic pump is operated, the first connecting pipe is closed by the closing operation of the first on-off valve, and the pressure oil from the first hydraulic pump corresponds. It is supplied to a predetermined actuator via a directional control valve, and a desired operation can be performed by operating the predetermined actuator. Similarly, when a predetermined actuator operated by the pressure oil discharged from the second hydraulic pump is operated, the second connecting pipe is closed by the closing operation of the second on-off valve, and the pressure oil from the second hydraulic pump corresponds. It is supplied to a predetermined actuator via a directional control valve, and a desired operation can be performed by operating the predetermined actuator.

  The present invention provides a communication line that can supply pressure oil discharged from a predetermined hydraulic pump among a plurality of hydraulic pumps to a suction side of another hydraulic pump different from the predetermined hydraulic pump, and the communication line. And an opening / closing valve that opens the communication line when the predetermined actuator is operated by the pressure oil discharged from the predetermined hydraulic pump and closes the communication line when the predetermined actuator is operated. Therefore, when the operation of a predetermined actuator that is operated by pressure oil discharged from a predetermined hydraulic pump is stopped, that is, when it is not operated, the open / close valve is opened to open the communication line. The pressure can be reduced to the same level, and the pipe resistance when returning the predetermined minimum flow rate from the predetermined hydraulic pump to the tank can be reduced. Thereby, the drive torque of a predetermined hydraulic pump can be suppressed small, and an energy loss can be reduced compared with the past. Further, when the predetermined actuator is not operated, the minimum hydraulic flow is supplied from the predetermined hydraulic pump to the suction side of the other hydraulic pump so that the suction performance of the other hydraulic pump is improved. be able to. As a result, the cavitation of other hydraulic pumps can be reduced as compared with the prior art, so that the excellent durability of the other hydraulic pumps can be ensured and the life of the other hydraulic pumps can be extended.

  The best mode for carrying out the hydraulic drive device for a work machine according to the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a side view showing a hydraulic excavator cited as an example of a working machine provided with a hydraulic drive device according to the present invention, and FIG. 2 is a hydraulic pressure showing a first embodiment of the hydraulic drive device provided in the hydraulic excavator shown in FIG. FIG. 3 is a hydraulic circuit diagram showing the operation of the first embodiment shown in FIG.

  The working machine provided with the first embodiment of the hydraulic drive device according to the present invention is, for example, a hydraulic excavator shown in FIG. 1, and the hydraulic excavator includes a traveling body 1 and a swiveling body disposed on the traveling body 1. 2 and a front work machine 3 that is attached to the swivel body 2 so as to be pivotable in the vertical direction and that performs excavation work or the like. The front work machine 3 includes a boom 4 attached to the revolving structure 2, an arm 5 attached to the tip of the boom 4, and a bucket 6 attached to the tip of the arm 5. Further, a boom cylinder 7 for operating the boom 4, an arm cylinder 8 for operating the arm 5, and a bucket cylinder 9 for operating the bucket 6 are included.

  In the first embodiment of the present invention, as shown in FIG. 2, a plurality of hydraulic pumps provided in a hydraulic excavator, for example, a first hydraulic pump 10 that is a variable displacement hydraulic pump driven by an engine (not shown), a second hydraulic pump. A pump 11 and a pilot pump 12 are provided. A predetermined actuator of the plurality of actuators provided in the hydraulic excavator, for example, the boom cylinder 7 described above is driven by the pressure oil discharged from the first hydraulic pump 10, and another predetermined actuator, for example, the arm cylinder described above. 8 is driven by pressure oil discharged from the second hydraulic pump 11. A boom directional control valve 15 for controlling the flow of pressure oil supplied from the first hydraulic pump 10 to the boom cylinder 7 is arranged in the main pipeline of the first hydraulic pump 10, and the main pipeline of the second hydraulic pump 11. An arm direction control valve 16 that controls the flow of pressure oil supplied from the second hydraulic pump 11 to the arm cylinder 8 is disposed in the path.

  Also, a boom operation device 17 for switching the boom direction control valve 15 and an arm operation device 18 for switching the arm direction control valve 16 are provided. For example, the displacement of the first hydraulic pump 10 described above is controlled in proportion to the operation of the boom operation device 17, and the second hydraulic pump 11 is operated by the arm operation device 18. The displacement volume is controlled in proportion to. That is, the displacement of the first hydraulic pumps 10 and 11 is controlled by positive control. In a state where the boom operation device 17 and the arm operation device 18 are held neutral, the displacement volume of the first hydraulic pumps 10 and 11 becomes a predetermined minimum volume, and the minimum flow rate corresponding to the minimum volume is the first hydraulic pressure. The pumps 10 and 11 are discharged. It is also possible to adopt a configuration in which the displacement of the first hydraulic pumps 10 and 11 is controlled by negative control.

  In the first embodiment, in particular, the hydraulic oil discharged from a predetermined hydraulic pump among the plurality of hydraulic pumps, that is, the first hydraulic pump 10 and the second hydraulic pump 11, is different from the predetermined hydraulic pump. A connecting line that can be supplied to the suction side of the pump, and the above-mentioned connecting line that is provided in this connecting line and that is operated by pressure oil discharged from a predetermined hydraulic pump is stopped. An open / close valve is provided that opens and closes the communication pipe line when a predetermined actuator is operated.

  For example, one end of the connecting pipe described above is connected to the main pipe of the first hydraulic pump 10, and the other end is connected to the suction pipe of the second hydraulic pump 11, and constitutes a predetermined hydraulic pump. The first connecting pipe 19 that can supply the pressure oil discharged from the second hydraulic pump 11 constituting the other hydraulic pump to the suction side, one end is connected to the main pipe of the second hydraulic pump 11, and the other end Is connected to the suction line of the first hydraulic pump 10 and the pressure oil of the second hydraulic pump 11 constituting the predetermined hydraulic pump can be supplied to the suction side of the first hydraulic pump 10 constituting the other hydraulic pump. It consists of two connecting lines 20.

  The on-off valve described above includes, for example, a first on-off valve 21 provided in the middle of the first communication pipe 19 and a second on-off valve 22 provided in the middle of the second communication pipe 21. The first on-off valve 21 and the second on-off valve 22 are constituted by, for example, hydraulically operated on-off valves that are switched by a pilot pressure that is a secondary pressure of the pressure oil discharged from the pilot pump 12.

  In the first embodiment configured as described above, for example, when the boom operation device 17 is operated, the boom direction control valve 15 is switched, the first on-off valve 21 is closed, and the first communication pipe 19 is closed. It is done. As a result, the pressure oil discharged from the first hydraulic pump 10 is supplied to the boom cylinder 7 via the main line and the boom direction control valve 15. Accordingly, the boom cylinder 7 is operated, and the boom 4 shown in FIG. 1 is rotated to perform a desired work via the boom 4.

  Further, when the arm operating device 18 is operated, the arm direction control valve 16 is switched, and the second on-off valve 22 is closed to close the second communication conduit 20. As a result, the pressure oil discharged from the second hydraulic pump 11 is supplied to the arm cylinder 8 via the main conduit and the arm direction control valve 16. Accordingly, the arm cylinder 8 is operated, and the arm 5 shown in FIG. 1 is rotated to perform a desired operation via the arm 5. When both the boom operation device 17 and the arm operation device 18 are operated, the above-described operations are performed in combination. By this combined operation, earth and sand excavation work and the like are performed.

  Further, for example, when the arm operating device 18 is operated to operate the arm cylinder 8 as described above and the arm operating device 18 is returned to the neutral position, the arm direction control valve 16 returns to the neutral position. Then, the supply of the pressure oil from the second hydraulic pump 11 to the arm cylinder 8 is stopped, the operation of the arm cylinder 8 is stopped, and the spring force of the second on-off valve 22 is changed to the pilot pressure as shown in FIG. The second on-off valve 22 is switched to the open position. Accordingly, the second communication pipe 20 is opened, and a predetermined minimum flow rate is transferred from the second hydraulic pump 11 to the suction side of the first hydraulic pump 10 via the second communication pipe 20 and the second on-off valve 22. Supplied to join.

  Similarly, although not shown, when the boom operating device 17 is operated to operate the boom cylinder 7 and the boom operating device 17 is returned to the neutral position, the boom direction control valve 15 is returned to the neutral position. Thus, the supply of pressure oil from the first hydraulic pump 10 to the boom cylinder 7 is stopped, the operation of the boom cylinder 7 is stopped, and the spring force of the first on-off valve 21 shown in FIG. The first opening / closing valve 21 is switched to the open position. Accordingly, the first communication pipe 19 is opened, and a predetermined minimum flow rate is transferred from the first hydraulic pump 10 to the suction side of the second hydraulic pump 11 via the first communication pipe 19 and the first on-off valve 21. Supplied to join.

  When both the boom operating device 17 and the arm operating device 18 are returned to neutral from the state where the boom 4 and the arm 5 are combined, that is, when the boom cylinder 7 and the arm cylinder 8 are not operated, the above-described operation is performed. Operations are performed in combination.

  In the first embodiment configured as described above, when the predetermined hydraulic pump, for example, the predetermined hydraulic actuator discharged from the first hydraulic pump 10, that is, the boom cylinder 7 is not operated, the first on-off valve is operated as described above. The first connecting pipe 19 is opened by opening the valve 21, and the minimum flow rate is supplied from the first hydraulic pump 10 to the suction side of the second hydraulic pump 11 through the first connecting pipe 19. At this time, since the first communication pipe 19 is connected to the suction side of another hydraulic pump, that is, the second hydraulic pump 11, the pressure is as low as the tank pressure. The pipe line resistance of the path 19 can be reduced. Thereby, the drive torque of the 1st hydraulic pump 10 can be restrained small, and an energy loss can be made small. Further, as described above, since the minimum flow rate from the first hydraulic pump 10 is supplied to the suction side of the second hydraulic pump 11 when the boom cylinder 7 is not operated, the second hydraulic pump 11 The suction performance can be improved. Thereby, since cavitation of the second hydraulic pump 11 can be reduced, the excellent durability of the second hydraulic pump 11 can be ensured, and the life of the second hydraulic pump 11 can be extended.

  In addition, when the predetermined actuator operated by the pressure oil discharged from the predetermined hydraulic pump, for example, the second hydraulic pump 11, that is, when the arm cylinder 8 is not operated, the second on-off valve 22 is opened as described above and the second communication is performed. The pipe line 20 is opened, and the minimum flow rate is supplied from the second hydraulic pump 11 to the suction side of the first hydraulic pump 10 via the second communication pipe line 20. At this time, the second communication pipe 20 is connected to the suction side of another hydraulic pump, that is, the first hydraulic pump 10, so that the pressure is as low as the tank pressure. The pipe resistance of the path 20 can be reduced. Thereby, the drive torque of the 2nd hydraulic pump 11 can be restrained small, and an energy loss can be made small. Further, as described above, since the minimum flow rate from the second hydraulic pump 11 is supplied to the suction side of the first hydraulic pump 10 when the arm cylinder 8 is not operated, the first hydraulic pump 10 The suction performance can be improved. Thereby, since cavitation of the first hydraulic pump 10 can be reduced, the excellent durability of the first hydraulic pump 10 can be ensured, and the life of the first hydraulic pump 10 can be extended.

[Second Embodiment]
FIG. 4 is a hydraulic circuit diagram showing a second embodiment of the hydraulic drive apparatus according to the present invention. In the second embodiment, the pressure oil of the first hydraulic pump 10 guided through the first connecting pipe 19 connecting the main pipe of the first hydraulic pump 10 and the suction pipe of the second hydraulic pump 11 is purified. Pressure oil of the second hydraulic pump 11 guided through the second connection pipe 20 that connects the first suction filter 23, the main pipe of the second hydraulic pump 11, and the suction pipe of the first hydraulic pump 10. And a second suction filter 24 for purification. The first suction filter 23 is disposed, for example, in the first connecting pipe 19 portion located downstream of the first on-off valve 21, and the second suction filter 24 is, for example, a second one located downstream of the second on-off valve 22. 2 It is arrange | positioned in 20 connecting pipe line parts. Other configurations are the same as those of the first embodiment described above.

  In the second embodiment configured as described above, the same effect as that of the first embodiment described above can be obtained. In addition, when the boom cylinder 7 or the arm cylinder 8 forming the predetermined actuator is not operated, the first hydraulic pump Foreign matter such as metal wear powder of pressure oil supplied from the second hydraulic pump 11 to the suction side of the second hydraulic pump 11 or from the second hydraulic pump 11 to the suction side of the first hydraulic pump 10 may be removed from the first suction filter 23 or the second suction filter 23. It is removed by the suction filter 24. Therefore, it is possible to supply clean pressure oil to the second hydraulic pump 11 constituting another hydraulic pump or the suction side of the first hydraulic pump 10, and the second hydraulic pump 11 and the first hydraulic pump 10 are connected to each other. Further, it is possible to protect the foreign matter contained in the pressure oil from being damaged.

[Third Embodiment]
FIG. 5 is a hydraulic circuit diagram showing a third embodiment of the hydraulic drive apparatus according to the present invention. In the third embodiment, a first on-off valve 21 is arranged at a connection point between the discharge conduit 10a of the first hydraulic pump 10 constituting the predetermined hydraulic pump and the first communication conduit 19, A second on-off valve 22 is arranged at a connection point between the discharge line 11 a of the second hydraulic pump 11 constituting the hydraulic pump and the second communication line 20. Other configurations are the same as those of the first embodiment described above.

  The third embodiment configured as described above can obtain the same effects as those of the first embodiment described above, and can be operated by pressure oil discharged from the first hydraulic pump 10 constituting the predetermined hydraulic pump. When the boom cylinder 7 constituting the actuator is not operated, the minimum flow rate from the first hydraulic pump 10 is reduced by the opening operation of the first on-off valve 21, so that the discharge conduit 10 a, the first on-off valve 21, and the first It is immediately supplied to the suction side of the second hydraulic pump 11 via the connecting pipe 19. Thereby, the pressure oil of the 1st hydraulic pump 10 can be rapidly supplied to the suction side of the 2nd hydraulic pump 11, and the outstanding responsiveness can be ensured.

  Similarly, when the arm cylinder 8 that constitutes a predetermined actuator that is operated by pressure oil discharged from the second hydraulic pump 11 that constitutes the predetermined hydraulic pump is not operated, the second on-off valve 22 opens to open the second hydraulic pressure. The minimum flow rate is immediately supplied from the pump 11 to the suction side of the first hydraulic pump 10 via the discharge line 11 a of the second hydraulic pump 11, the second on-off valve 22, and the second communication line 20. Thereby, the pressure oil of the 2nd hydraulic pump 11 can be rapidly supplied to the suction side of the 1st hydraulic pump 10, and the outstanding responsiveness can be ensured.

[Fourth Embodiment]
FIG. 6 is a hydraulic circuit diagram showing a fourth embodiment of the hydraulic drive apparatus according to the present invention. In the fourth embodiment, for example, the first communication pipeline 19 and the first on-off valve 21 are excluded from the configuration of the first embodiment described above. That is, it has one connecting line 20A that connects the main line of the second hydraulic pump 11 and the suction line of the first hydraulic pump 10, and one on-off valve 22A provided in the connecting line 20A. It has a configuration. Other configurations are the same as those of the first embodiment described above.

  The fourth embodiment configured as described above can obtain the operation and effects excluding the operation and effects obtained by providing the first communication pipe line 19 and the first on-off valve 21 in the first embodiment described above. That is, when the arm operation device 18 is returned to neutral from the state where the arm operation device 18 is operated to operate the arm cylinder 8 as described above, the arm direction control valve 16 returns to the neutral position. Thus, the supply of pressure oil from the second hydraulic pump 11 to the arm cylinder 8 is stopped, the operation of the arm cylinder 8 is stopped, and the spring force of the on-off valve 22A becomes larger than the force by the pilot pressure. The second on-off valve 22 is switched to the open position. Accordingly, the communication line 20A is opened, and a predetermined minimum flow rate is supplied from the second hydraulic pump 11 so as to join the suction side of the first hydraulic pump 10 via the connection line 20A and the on-off valve 22A. The As a result, the driving torque of the second hydraulic pump 11 can be kept small, energy loss can be reduced, and the suction performance of the first hydraulic pump 10 can be improved. The durability can be ensured and the life of the first hydraulic pump 10 can be extended.

  In the fourth embodiment, the first connecting pipe 19 and the first on-off valve 21 are excluded from the configuration of the first embodiment. On the contrary, the configuration of the first embodiment is used. Alternatively, the second communication pipe line 20 and the second on-off valve 22 may be omitted.

[Fifth Embodiment]
FIG. 7 is a hydraulic circuit diagram showing a fifth embodiment of the hydraulic drive apparatus according to the present invention. The fifth embodiment includes a boom operation device 17A having an electric lever and an arm operation device 18A having an electric lever, and an operation signal from the boom operation device 17A or an operation signal from the arm operation device 18A. A controller 25 is provided for inputting and outputting a signal for switching the electromagnetically operated boom direction control valve 15A or a signal for switching the electromagnetically operated arm direction control valve 16A. In addition, the first on-off valve 21B provided in the first communication line 19 that connects the main line of the first hydraulic pump 10 and the suction line of the second hydraulic pump 11, and the main line and the second line of the second hydraulic pump 11 are connected. 1 Each of the second on-off valves 22B provided in the second communication line 20 that connects the suction line of the hydraulic pump 10 is output from the controller 25 in accordance with the operation of the boom operation device 17A and the arm operation device 18A. It consists of an electromagnetically operated on-off valve that can be switched by a signal. Other configurations are the same as those of the first embodiment described above.

  In the fifth embodiment configured as described above, the first on-off valve 21B is opened in response to the neutral return of the boom operation device 17a or the arm operation device 18A, and the first communication conduit 19 is opened, or The second on-off valve 22B is opened to open the second communication conduit 20, and the same effect as that of the first embodiment described above can be obtained.

[Sixth Embodiment]
FIG. 8 is a hydraulic circuit diagram showing a sixth embodiment of the hydraulic drive apparatus according to the present invention. The sixth embodiment includes a third hydraulic pump 26 in addition to the first hydraulic pump 10 and the second hydraulic pump 11. In addition, an actuator that is operated by the pressure oil discharged from the third hydraulic pump 26, for example, a special attachment cylinder 27, and an attachment that controls the flow of the pressure oil supplied from the third hydraulic pump 26 to the special attachment cylinder 27. And a directional control valve 28 and an attachment operating device 29 that is connected to the pilot pump 12 and switches the directional control valve 28 for attachment.

  In the sixth embodiment, the connecting pipe can supply the pressure oil discharged from the first hydraulic pump 10 constituting the predetermined hydraulic pump to the suction side of the third hydraulic pump 26 constituting the other hydraulic pump. 19A of 1st connection pipes, and the 2nd connection pipe which can supply the pressure oil discharged from the 2nd hydraulic pump 11 which comprises a predetermined hydraulic pump to the suction side of the 3rd hydraulic pump 26 which comprises another hydraulic pump 20A. The first connection pipe 19 is provided with a first on-off valve 21 equivalent to the above-described first embodiment, and the second connection pipe 20 is provided with a second on-off valve equivalent to the above-described first embodiment. 22 is provided. Other configurations are the same as those of the first embodiment described above.

  In the sixth embodiment configured as described above, for example, instead of the bucket 6 of the hydraulic excavator shown in FIG. 1, a special attachment such as a gripping device or a pile driving machine is attached, and the operation of the attachment operation device 29 is performed. Accordingly, the attachment direction control valve 28 is switched, and the pressure oil discharged from the third hydraulic pump 26 is supplied to the special attachment cylinder 27 via the attachment direction control valve 28, and the special attachment cylinder 27 is Operate. Thereby, a desired work by a special attachment can be performed.

  Further, when the predetermined actuator that is operated by the pressure oil discharged from the first hydraulic pump 10, that is, the boom cylinder 7 is not operated, the first on-off valve 21 opens and the first communication pipe 19 </ b> A is opened. A minimum flow rate is supplied from the first hydraulic pump 10 to the suction side of the third hydraulic pump 26 via the first communication line 19A. As a result, the driving torque of the first hydraulic pump 10 can be kept small, and the suction performance of the third hydraulic pump 26 can be improved.

  Further, when the predetermined actuator that is operated by the pressure oil discharged from the second hydraulic pump 11, that is, the arm cylinder 8 is not operated, the second on-off valve 21 is opened to open the third communication line 20 </ b> A. The minimum flow rate is supplied from the second hydraulic pump 11 to the suction side of the third hydraulic pump 26 via the second communication pipe 20A. As a result, the driving torque of the second hydraulic pump 11 can be kept small, and the suction performance of the third hydraulic pump 26 can be improved.

  The non-operation of a predetermined actuator that is operated by pressure oil discharged from the first hydraulic pump 10, that is, the boom cylinder 15, and the predetermined actuator that is operated by pressure oil discharged from the second hydraulic pump 11, that is, the arm cylinder 16 When the non-operation is performed at the same time, the above-described operation is performed in combination.

  As in the first embodiment described above, when the boom cylinder 7 is operated by the pressure oil discharged from the first hydraulic pump 10, the first connecting pipe 19A is closed by the closing operation of the first on-off valve 21. Thus, the pressure oil from the first hydraulic pump 10 is supplied to the boom cylinder 7 via the boom direction control valve 15, and a desired operation by driving the boom 4 can be performed. Similarly, when the arm cylinder 8 is operated by the pressure oil discharged from the second hydraulic pump 11, the second connecting pipe 20 </ b> A is closed by the closing operation of the second on-off valve 22, and the pressure oil from the second hydraulic pump 10 is closed. Is supplied to the arm cylinder 8 via the arm direction control valve 16, and a desired operation by driving the arm 5 can be performed.

It is a side view which shows the hydraulic excavator mentioned as an example of the working machine with which the hydraulic drive device which concerns on this invention is provided. FIG. 2 is a hydraulic circuit diagram showing a first embodiment of a hydraulic drive device provided in the hydraulic excavator shown in FIG. 1. FIG. 3 is a hydraulic circuit diagram showing an operation of the first embodiment shown in FIG. 2. It is a hydraulic circuit diagram which shows 2nd Embodiment of the hydraulic drive device which concerns on this invention. FIG. 5 is a hydraulic circuit diagram showing a third embodiment of a hydraulic drive device according to the present invention. It is a hydraulic circuit diagram which shows 4th Embodiment of the hydraulic drive device which concerns on this invention. FIG. 9 is a hydraulic circuit diagram showing a fifth embodiment of a hydraulic drive device according to the present invention. It is a hydraulic circuit diagram which shows 6th Embodiment of the hydraulic drive device which concerns on this invention.

Explanation of symbols

3 Front working machine 4 Boom 5 Arm 7 Boom cylinder (predetermined actuator)
8 Arm cylinder (predetermined actuator)
9 Bucket cylinder 10 First hydraulic pump (predetermined hydraulic pump) (other hydraulic pump)
10a Discharge line 11 Second hydraulic pump (predetermined hydraulic pump) (other hydraulic pump)
11a Discharge pipe 12 Pilot pump 15 Boom direction control valve 15A Boom direction control valve 16 Arm direction control valve 16A Arm direction control valve 17 Boom operation device 17A Boom operation device 18 Arm operation device 18A Arm operation Device 19 First connection line 19A First connection line 20 Second connection line 20A Second connection line 21 First on-off valve 21B First on-off valve 22 Second on-off valve 22A Second on-off valve 22B Second on-off valve 23 First Suction Filter 24 Second Suction Filter 25 Controller 26 Third Hydraulic Pump (Other Hydraulic Pump)
27 Cylinder for special attachment 28 Direction control valve for attachment 29 Operating device for attachment

Claims (5)

A plurality of hydraulic pumps provided in the work machine, a plurality of actuators driven by pressure oil discharged from these hydraulic pumps, and a plurality of pressure oils supplied to each of the actuators from the hydraulic pump. In a hydraulic drive device for a work machine provided with a directional control valve,
A connecting line capable of supplying pressure oil discharged from a predetermined hydraulic pump of the plurality of hydraulic pumps to a suction side of another hydraulic pump different from the predetermined hydraulic pump;
The communication pipe is opened when the operation of the predetermined actuator among the actuators provided by the pressure oil discharged from the predetermined hydraulic pump is stopped, and the operation of the predetermined actuator is performed. A hydraulic drive device for a working machine, comprising: an opening / closing valve for closing the communication pipe. In the invention of claim 1,
The plurality of hydraulic pumps includes a first hydraulic pump and a second hydraulic pump,
A first communication line capable of supplying pressure oil discharged from the first hydraulic pump as the predetermined hydraulic pump to a suction side of the second hydraulic pump as the other hydraulic pump; The second hydraulic pump that is the predetermined hydraulic pump comprises a second connecting pipe that can supply pressure oil to the suction side of the first hydraulic pump that is the other hydraulic pump,
The hydraulic drive device for a working machine, wherein the on-off valve includes a first on-off valve provided in the first communication pipe and a second on-off valve provided in the second communication pipe. In the invention of claim 1,
A hydraulic drive device for a working machine, wherein the on-off valve is arranged at a connection point between the discharge line of the predetermined hydraulic pump and the communication line. In the invention of claim 1,
The plurality of hydraulic pumps includes a first hydraulic pump and a second hydraulic pump,
The connecting line is configured to supply pressure oil supplied from the predetermined hydraulic pump, which is one of the first hydraulic pump and the second hydraulic pump, to the first hydraulic pump and the second hydraulic pump. It consists of one connecting pipe that can be supplied to the suction side of the other hydraulic pump that is the other,
The hydraulic drive device for a working machine, wherein the on-off valve is composed of one on-off valve provided in the one communication pipe. In the invention of claim 1,
The plurality of hydraulic pumps include a first hydraulic pump, a second hydraulic pump, and a third hydraulic pump,
The communication pipe is capable of supplying the pressure oil discharged from the first hydraulic pump to the suction side of the third hydraulic pump, and the pressure oil discharged from the second hydraulic pump is the above. A second connecting pipe that can be supplied to the suction side of the third hydraulic pump;
The hydraulic drive device for a working machine, wherein the on-off valve includes a first on-off valve provided in the first communication pipe and a second on-off valve provided in the second communication pipe.

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