Hydraulic Drive Unit

Abstract

To provide a hydraulic drive device capable of suppressing shortage of a flow rate of a working fluid to be supplied to hydraulic apparatuses in simultaneously driving two or more hydraulic apparatuses.SOLUTION: A hydraulic drive device drives a plurality of hydraulic apparatuses including at least first to third hydraulic apparatuses by supplying a working fluid thereto, and includes: a plurality of pumps including at least a first pump connected to the first hydraulic apparatus and a second pump connected to the second hydraulic apparatus; a confluence passage connected to the plurality of pumps for merging the working fluids discharged from the plurality of pumps; a flow rate control valve connected to the confluence passage and the third hydraulic apparatus, and controlling the flow rate of the working fluid flowing from the confluence passage to the third hydraulic apparatus by adjusting an opening according to an input flow rate control signal; and a pressure compensation valve disposed at a third hydraulic apparatus side with respect to a confluence point where the working fluids are merged in the confluence passage, and keeping front-rear differential pressure of the flow rate control valve at a prescribed pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydraulic drive device that drives a plurality of hydraulic devices by supplying hydraulic fluid to each of the hydraulic devices. [Background technology]

[0002] There are known hydraulic drive systems that use a single pump to drive multiple hydraulic devices, such as cylinders and motors. For example, Patent Document 1 discloses a hydraulic drive system such as this. In the hydraulic drive system disclosed in Patent Document 1, a directional control valve and a pressure compensation valve are provided for each hydraulic device. Therefore, the hydraulic drive system allows pressurized oil to flow to each hydraulic device at a flow rate that corresponds to the opening of the flow control valve, regardless of the load on the hydraulic device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-156355 Summary of the Invention [Problem to be solved by the invention]

[0004] The hydraulic drive system of Patent Document 1 uses one pump to drive multiple hydraulic devices, which presents the following problem: When two hydraulic devices are driven simultaneously, the pump discharge flow rate may be insufficient to meet the total flow rate required for each of the hydraulic devices. In this case, the supply flow rate to the hydraulic device with the largest load will be particularly insufficient.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic drive device that can prevent the flow rate of hydraulic fluid supplied to hydraulic devices from becoming insufficient when two hydraulic devices are driven simultaneously. [Means for solving the problem]

[0006] The hydraulic drive device of the present invention is a hydraulic drive device that supplies hydraulic fluid to each of a plurality of hydraulic devices including at least first to third hydraulic devices to drive them, and is equipped with a plurality of pumps including at least a first pump connected to the first hydraulic device and a second pump connected to the second hydraulic device, a junction passage connected to the plurality of pumps and for merging hydraulic fluid discharged from each of the plurality of pumps, a flow control valve connected to the junction passage and the third hydraulic device and controlling the flow rate of hydraulic fluid flowing from the junction passage to the third hydraulic device by adjusting its opening in accordance with an input flow control signal, and a pressure compensation valve provided in the junction passage on the third hydraulic device side of the junction point where the hydraulic fluids merge, and for maintaining a predetermined differential pressure across the flow control valve.

[0007] According to the present invention, a pressure compensation valve and a flow control valve are provided on the third hydraulic device side of the junction point of the junction passage. Therefore, hydraulic fluid discharged from each pump can be joined and guided to the third hydraulic device via the pressure compensation valve and the flow control valve. For example, even when hydraulic fluid is supplied from the first pump to the first hydraulic device to simultaneously drive the first and third hydraulic devices, a sufficient flow rate of hydraulic fluid can be guided to the third hydraulic device. Therefore, when the first and third hydraulic devices are simultaneously driven, a shortage of hydraulic fluid supplied to the third hydraulic device can be prevented. Similarly, when the second and third hydraulic devices are simultaneously driven, a shortage of hydraulic fluid supplied to the third hydraulic device can be prevented.

[0008] Furthermore, according to the present invention, the pressure compensation valve and the flow control valve are provided closer to the third hydraulic device than the junction point of the junction passage, so the number of pressure compensation valves and flow control valves can be reduced, thereby reducing the number of parts in the hydraulic drive device. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent the flow rate of the hydraulic fluid supplied to the hydraulic devices from becoming insufficient when two hydraulic devices are driven simultaneously. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a circuit diagram showing a hydraulic circuit of a hydraulic drive system according to a first embodiment of the present invention. [Figure 2] 2 is a circuit diagram showing the flow of hydraulic fluid in the hydraulic circuit of FIG. 1. FIG. [Figure 3] FIG. 5 is a circuit diagram showing a hydraulic circuit of a hydraulic drive unit according to a second embodiment of the present invention. [Figure 4] FIG. 6 is a circuit diagram showing a hydraulic circuit of another hydraulic drive device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, hydraulic drive units 1, 1A according to first and second embodiments of the present invention will be described with reference to the drawings. Note that the concepts of directions used in the following description are used for the convenience of explanation and do not limit the orientation of the configuration of the invention to those directions. Furthermore, the hydraulic drive units 1, 1A described below are merely one embodiment of the present invention. Therefore, the present invention is not limited to the embodiment, and additions, deletions, and modifications are possible within the scope of the invention.

[0012] First Embodiment The hydraulic drive unit 1 shown in FIG. 1 is provided in a vehicle or the like including a plurality of hydraulic devices (for example, hydraulic cylinders and hydraulic motors), for example, a construction vehicle such as a hydraulic shovel and an industrial vehicle such as a lift (neither of which are shown). In this embodiment, the hydraulic drive unit 1 is provided in a hydraulic shovel. Note that the hydraulic drive unit 1 is not limited to vehicles or the like, and may be a hydraulic robot or the like. A hydraulic shovel can perform various tasks by operating, for example, a traveling device, a revolving body, a boom, an arm, an attachment, and the like. More specifically, the hydraulic shovel is provided with a plurality of hydraulic devices 2 to 4 including first to third hydraulic devices 2 to 4 shown in FIG. 1. The plurality of hydraulic devices 2 to 4 are hydraulic cylinders or hydraulic motors. In this embodiment, the plurality of hydraulic devices 2 to 4 includes six hydraulic devices 2 to 4, for example, left and right traveling motors, a revolving motor, a boom cylinder, an arm cylinder, and an attachment cylinder. For convenience of explanation, hydraulic devices other than the three first to third hydraulic devices 2-4 are omitted in FIG. 1. Each of the first and second hydraulic devices 2, 3 is, for example, a left or right travel motor, a swing motor, a boom cylinder, or an arm cylinder. The third hydraulic device 4 is, for example, a hydraulic device for an attachment. The hydraulic device for an attachment is, for example, a drill motor, a grapple cylinder, or a tilt cylinder. However, the hydraulic device for an attachment may also be a hydraulic cylinder or hydraulic motor used for purposes other than the motors and cylinders described above. In a hydraulic excavator, the traveling gear, the swing body, the boom, the arm, and the attachment can each be operated by supplying hydraulic fluid (e.g., oil, water, etc.) to each of the hydraulic devices 2-4. This allows the hydraulic excavator to perform a variety of tasks.

[0013] <Hydraulic drive unit> The hydraulic drive unit 1 includes a plurality of pumps 11L, 11R, a multiple control valve block 12, and a control valve block 13. In this embodiment, the hydraulic drive unit 1 includes two pumps 11L, 11R. The hydraulic drive unit 1 controls the flow of hydraulic fluid to a plurality of hydraulic devices 2 to 4. More specifically, the hydraulic drive unit 1 controls the direction and flow rate of the hydraulic fluid flowing to the plurality of hydraulic devices 2 to 4.

[0014] <Pump> The two pumps 11L, 11R are rotationally driven by a drive source (e.g., an engine or an electric motor) not shown. As a result, each of the two pumps 11L, 11R discharges hydraulic fluid. The two pumps 11L, 11R are, for example, variable displacement swash plate pumps. However, the two pumps 11L, 11R may also be bent-axis pumps or fixed displacement pumps.

[0015] <Multiple control valve block> The multiple control valve block 12 includes a plurality of directional control valves 21, 22, including the first directional control valve 21 and the second directional control valve 22 shown in FIG. 1. Furthermore, a first pump passage 23L and a second pump passage 23R are formed in the multiple control valve block 12. The multiple control valve block 12 is connected to a plurality of hydraulic devices 2, 3, excluding the third hydraulic device 4. In other words, the multiple control valve block 12 is connected to a plurality of hydraulic devices 2, 3, including the first hydraulic device 2 and the second hydraulic device 3 shown in FIG. 1. The multiple control valve block 12 controls the flow of hydraulic fluid discharged from each of the pumps 11L, 11R to the plurality of hydraulic devices 2, 3.

[0016] The first pump passage 23L is connected to the first pump 11L. The working fluid discharged from the first pump 11L flows through the first pump passage 23L. The second pump passage 23R is connected to the second pump passage 23R. The working fluid discharged from the second pump 11R flows through the second pump passage 23R.

[0017] At least one of the plurality of directional control valves 21, 22 is provided for each of the plurality of hydraulic devices 2, 3. Therefore, the multiple control valve block 12 includes the same or more number of directional control valves 21, 22 as the plurality of hydraulic devices 2, 3. The plurality of directional control valves 21, 22 are connected to the corresponding hydraulic devices 2, 3. The plurality of directional control valves 21, 22 are also connected to either the first pump passage 23L or the second pump passage 23R. More specifically, the plurality of directional control valves 21, 22 are connected to the pump passages 23L, 23R in parallel with other directional control valves (not shown) connected to the same pump passages 23L, 23R. Each of the plurality of directional control valves 21, 22 controls the direction and flow rate of the hydraulic fluid flowing to the corresponding hydraulic device 2, 4. Each of the multiple directional control valves 21, 22 has the same configuration, except that the hydraulic devices 2, 3 to which they are connected are different and that they are connected to either the pump passages 23L, 23R. Therefore, the following description will be given taking the first directional control valve 21 and the second directional control valve 22 included in the multiple directional control valves 21, 22 as examples, and illustrations and descriptions of the other directional control valves will be omitted.

[0018] A first direction control valve 21, which is an example of a first control valve, is provided between the first pump 11L and the first hydraulic device 2. The first direction control valve 21 controls the flow rate of hydraulic fluid flowing from the first pump 11L to the first hydraulic device 2. The first direction control valve 21 also switches the direction of hydraulic fluid flowing from the first pump 11L to the first hydraulic device 2. More specifically, the first direction control valve 21 is, for example, a spool valve, and is connected to a first pump passage 23L, a tank 24, and the first hydraulic device 2. The first direction control valve 21 switches the connection destination of each of the two ports 2a, 2b of the first hydraulic device 2 between the first pump passage 23L and the tank 24 in response to an input first signal, thereby switching the direction of hydraulic fluid flowing to the first hydraulic device 2. The first directional control valve 21 controls the flow rate of the hydraulic fluid flowing through the first hydraulic device 2 by changing its opening in response to an input first signal. The first signal is a signal output from a control device or operating device (not shown), and is a pressure signal such as a pilot pressure, or an electric signal. The same applies to the second signal and flow rate control signal described below.

[0019] A second direction control valve 22, which is an example of a second control valve, is provided between the second pump 11R and the second hydraulic device 3. The second direction control valve 22 switches the direction of hydraulic fluid flowing from the second pump 11R to the second hydraulic device 3. Furthermore, the second direction control valve 22 controls the flow rate of hydraulic fluid flowing from the second pump 11R to the second hydraulic device 3. More specifically, the second direction control valve 22 is, for example, a spool valve, and is connected to the first pump passage 23L, the tank 24, and the second hydraulic device 3. The second direction control valve 22 switches the connection destination of each of the two ports 3a, 3b of the second hydraulic device 3 between the first pump passage 23L and the tank 24 in response to an input second signal, thereby switching the direction of hydraulic fluid flowing to the second hydraulic device 3. The second direction control valve 22 controls the flow rate of the hydraulic fluid flowing through the second hydraulic device 3 by changing the opening degree in response to the second signal input thereto.

[0020] <Control valve block> The control valve block 13 includes a junction passage 31, a flow control valve 32, and a pressure compensation valve 33. The control valve block 13 also includes a plurality of check valves (two check valves in this embodiment) 34L, 34R. The control valve block 13 is connected to the two pump passages 23L, 23R and the third hydraulic device 4. The control valve block 13 joins the hydraulic fluids discharged from the pumps 11L, 11R and causes them to flow to the third hydraulic device 4. The control valve block 13 then controls the flow of the hydraulic fluid flowing to the third hydraulic device 4.

[0021] The junction passage 31 is connected to the two pumps 11L, 11R. More specifically, the junction passage 31 is connected to the first pump passage 23L and the second pump passage 23R. The junction passage 31 is connected to the two pumps 11L, 11R via the passages 23L, 23R. The junction passage 31 joins the hydraulic fluids discharged from the two pumps 11L, 11R at a junction point 31a. More specifically, the junction passage 31 has a first connection portion 31b, a second connection portion 31c, and a junction portion 31d. The first connection portion 31b is connected to the first pump passage 23L, and the second connection portion 31c is connected to the second pump passage 23R. The junction portion 31d is connected to the first connection portion 31b and the second connection portion 31c at the junction point 31a. Then, the hydraulic fluid flowing through the first connecting portion 31b and the second connecting portion 31c joins at the joining point 31a and flows into the joining portion 31d.

[0022] The flow control valve 32 is connected to the junction passage 31 and the third hydraulic device 4. More specifically, the flow control valve 32 is connected to the junction portion 31d of the junction passage 31 and is connected to the two pumps 11L, 11R via the junction passage 31. The flow control valve 32 controls the flow of the hydraulic fluid that has joined in the junction passage 31 to the third hydraulic device 4. More specifically, the flow control valve 32 adjusts its opening in response to an input flow control signal to control the flow rate of the hydraulic fluid that flows from the junction passage 31 to the third hydraulic device 4. Furthermore, the flow control valve 32 switches the direction of the hydraulic fluid that flows from the junction passage 31 to the third hydraulic device 4 in response to the input flow control signal. More specifically, the flow control valve 32 is connected to the junction passage 31, the tank 24, and two ports 4a, 4b of the third hydraulic device 4. The flow control valve 32 switches the direction of the hydraulic fluid flowing to the third hydraulic device 4 by switching the connection destinations of the two ports 4a, 4b of the third hydraulic device 4 between the junction passage 31 and the tank 24, respectively. The flow control valve 32 also controls the flow rate of the hydraulic fluid flowing to the third hydraulic device 4 by changing its opening in response to an input flow control signal.

[0023] The pressure compensating valve 33 is provided closer to the third hydraulic device 4 than the junction 31a. In this embodiment, the pressure compensating valve 33 is disposed between the junction 31a and the flow control valve 32. That is, the pressure compensating valve 33 is disposed at the junction portion 31d of the junction passage 31. The pressure compensating valve 33 maintains the differential pressure across the flow control valve 32 at a predetermined pressure. More specifically, the pressure compensating valve 33 receives pressures across the flow control valve 32 in opposing directions, thereby adjusting the aperture of the junction portion 31d so that the differential pressure across the flow control valve 32 becomes the predetermined pressure. As a result, the flow control valve 32 can flow hydraulic fluid to the flow control valve 32 at a flow rate corresponding to the aperture of the flow control valve 32, regardless of the load on the third hydraulic device 4. That is, the flow control valve 32 can flow hydraulic fluid to the third hydraulic device 4 at a flow rate corresponding to the input flow control signal.

[0024] The two check valves 34L, 34R are provided in the junction passage 31 between the junction point 31a and each of the two pumps 11L, 11R. That is, the two check valves 34L, 34R are interposed between the first connection portion 31b and the second connection portion 31c of the junction passage 31. The two check valves 34L, 34R allow the flow of hydraulic fluid from the connected pumps 11L, 11R to the junction point 31a, and prevent the flow of hydraulic fluid in the opposite direction (i.e., from the junction point 31a to the pumps 11L, 11R).

[0025] <Installation of control valve block to multiple control valve block> The control valve block 13 is configured as a separate body from the multiple control valve block 12. The control valve block 13 is attached to the multiple control valve block 12. The control valve block 13 and its attachment to the multiple control valve block 12 will be described in more detail below.

[0026] The multiple control valve block 12 includes a first block body 41. The first pump passage 23L and the second pump passage 23R are formed in the first block body 41. The plurality of directional control valves 21, 22 have spools 21a, 22a, respectively. The plurality of directional control valves 21, 22 are configured by movably inserting the spools 21a, 22a into the first block body 41.

[0027] The control valve block 13 includes a second block body 42. The junction passage 31 is formed in the second block body 42. The flow control valve 32 has a spool 32a. The flow control valve 32 is configured by movably inserting the spool 32a into the second block body 42. The pressure compensating valve 33 also has a spool 33a. The pressure compensating valve 33 is configured by movably inserting the spool 33a into the second block body 42. The second block body 42 is fastened to the first block body 41 so as to connect the junction passage 31 to the two pump passages 23L, 23R. In this way, the control valve block 13 is attached to the multiple control valve block 12.

[0028] <Operation of the hydraulic drive unit> In the hydraulic drive unit 1, when the first hydraulic device 2 and the third hydraulic device 4 are driven simultaneously, a first signal and a flow rate control signal are input to the first directional control valve 21 and the flow rate control valve 32, respectively. Then, the hydraulic fluid discharged from the first pump 11L is supplied to the first hydraulic device 2 in a direction according to the first signal by the first directional control valve 21. In addition, the flow rate of the hydraulic fluid supplied from the first pump 11L to the first hydraulic device 2 is controlled by the first directional control valve 21 according to the first signal.

[0029] The flow control valve 32 causes the hydraulic fluid discharged from the two pumps 11L, 11R and joined in the joining passage 31 to flow to the third hydraulic device 4 in a direction corresponding to the flow control signal (see the solid line in FIG. 2). The joined hydraulic fluid is supplied to the third hydraulic device 4 by the flow control valve 32 at a flow rate corresponding to the flow control signal. More specifically, in the hydraulic drive unit 1, the pressures before and after the flow control valve 32 act on the pressure compensating valve 33 so as to oppose each other (see the dotted lines A and B in FIG. 2). As a result, the differential pressure before and after the flow control valve 32 is maintained at a predetermined pressure by the pressure compensating valve 33. Therefore, the hydraulic fluid can be caused to flow to the third hydraulic device 4 at a flow rate corresponding to the opening of the flow control valve 32. In other words, in the hydraulic drive unit 1, the hydraulic fluid can be caused to flow to the third hydraulic device 4 at a flow rate corresponding to the flow control signal. Therefore, when the hydraulic drive unit 1 simultaneously drives the first and third hydraulic devices 2, 4, it can move the third hydraulic device 4 at a speed corresponding to the flow rate control signal regardless of the load on the third hydraulic device 4. The same applies when simultaneously driving the second and third hydraulic devices 3, 4 and when simultaneously driving the first to third hydraulic devices 2-4. That is, in these cases as well, the hydraulic fluids discharged from the two pumps 11L, 11R can be joined in the joining passage 31, so it is possible to move the third hydraulic device 4 at a speed corresponding to the flow rate control signal regardless of the load on the third hydraulic device 4.

[0030] In the hydraulic drive unit 1 of this embodiment, a pressure compensation valve 33 and a flow control valve 32 are provided on the second hydraulic device 3 side of the junction point 31a of the junction passage 31. Therefore, the hydraulic fluids discharged from the pumps 11L and 11R can be joined and guided to the third hydraulic device 4 via the pressure compensation valve 33 and the flow control valve 32. As a result, even when hydraulic fluid is supplied from the first pump 11L to the first hydraulic device 2 to simultaneously drive the first hydraulic device 2 and the third hydraulic device 4, a sufficient flow rate of hydraulic fluid can be guided to the third hydraulic device 4. Therefore, when the first hydraulic device 2 and the third hydraulic device 4 are simultaneously driven, a shortage of hydraulic fluid supplied to the third hydraulic device 4 can be prevented. Similarly, when the second hydraulic device 3 and the third hydraulic device 4 are simultaneously driven, and when the first to third hydraulic devices 2 to 4 are simultaneously driven, a shortage of hydraulic fluid supplied to the third hydraulic device 4 can be prevented.

[0031] Furthermore, in the hydraulic drive unit 1 of this embodiment, the pressure compensating valve 33 and the flow control valve 32 are provided closer to the third hydraulic device 4 than the junction 31a of the junction passage 31, so it is possible to reduce the number of pressure compensating valves 33 and flow control valves 32. To explain in more detail, as in the hydraulic drive unit 1 of this embodiment, it is sufficient to provide only one pressure compensating valve 33 and one flow control valve 32 for the third hydraulic device 4, and it is not necessary to provide a pressure compensating valve 33 and a flow control valve 32 for each of the pumps 11L, 11R. Therefore, the number of parts of the hydraulic drive unit 1 can be reduced.

[0032] Furthermore, in the hydraulic drive unit 1 of this embodiment, check valves 34L, 34R are provided between the junction 31a and each of the pumps 11L, 11R in the junction passage 31. This makes it possible to prevent backflow of the hydraulic fluid to each of the pumps 11L, 11R.

[0033] Furthermore, in the hydraulic drive system 1 of this embodiment, the control valve block 13 is separate from the multiple control valve block 12. Therefore, the control valve block 13 can be retrofitted to an existing multiple control valve block 12. The hydraulic drive system 1 can be easily manufactured.

[0034] Second Embodiment The hydraulic drive system 1A of the second embodiment is similar in configuration to the hydraulic drive system 1 of the first embodiment. Therefore, the configuration of the hydraulic drive system 1A of the second embodiment will be mainly described in terms of differences from the hydraulic drive system 1 of the first embodiment, and the same components will be assigned the same reference numerals and descriptions thereof will be omitted.

[0035] As shown in Fig. 3, the hydraulic drive unit 1A of the second embodiment includes three pumps 11L, 11R, and 11M, a multiple control valve block 12A, and a control valve block 13A. The third pump 11M is configured similarly to the first and second pumps 11L and 11R. That is, the third pump 11M discharges hydraulic fluid by being rotationally driven by a drive source (not shown). Note that the first to third pumps 11L, 11R, and 11M do not necessarily have to be configured similarly.

[0036] The multiple control valve block 12A includes a plurality of directional control valves. The illustration of the directional control valves is omitted in FIG. 3 . The multiple control valve block 12A further includes a third pump passage 23M in addition to the first and second pump passages 23L and 23R. The third pump passage 23M is connected to the third pump 11M. Each of the directional control valves is connected to one of the first to third pump passages 23L, 23R, and 23M. Each of the directional control valves is connected to a passage 23L, 23R, or 23M in parallel with the other directional control valves connected to the same passage 23L, 23R, or 23M.

[0037] The control valve block 13A includes a junction passage 31A, a flow control valve 32, a pressure compensation valve 33, and three check valves 34L, 34R, and 34M. The junction passage 31A is also connected to the third pump 11M via the third pump passage 23M. The junction passage 31A joins the hydraulic fluids discharged from the three pumps 11L, 11R, and 11M at a junction point 31a. The check valve 34M is provided between the junction point 31a and the third pump 11M (i.e., at the third connection portion 31e). The check valve 34M allows hydraulic fluid to flow from the third pump 11M to the junction point 31a and prevents hydraulic fluid from flowing in the reverse direction.

[0038] The hydraulic drive system 1A of the second embodiment has the same effects as the hydraulic drive system 1 of the first embodiment.

[0039] <Other embodiments> The hydraulic drive units 1, 1A of the first and second embodiments may be provided with four or more pumps, and may have five or fewer or seven or more directional control valves. Furthermore, in the hydraulic drive units 1, 1A of the first and second embodiments, the pressure compensating valve 33 may be provided between the flow control valve 32 and the second hydraulic device 3. Furthermore, in the hydraulic drive units 1, 1A of the first and second embodiments, a pressure compensating valve may be provided for each of the plurality of directional control valves. Furthermore, in the hydraulic drive units 1, 1A, the plurality of directional control valves 21, 22 may be center-open spool valves that open and close the pump passages 23L, 23R.

[0040] Furthermore, a hydraulic drive unit 1B of another embodiment may be configured as follows. That is, each of the pumps 11L, 11R, and 11M may be connected to another hydraulic device 5 via another junction passage 31B as shown in FIG. 4 . The aforementioned flow control valve 32B and pressure compensation valve 33B are connected to the other junction passage 31B. That is, the other hydraulic device 5, flow control valve 32B, and pressure compensation valve 33B are connected to each of the pumps 11L, 11R, and 11M in parallel with the aforementioned hydraulic device 4, flow control valve 32, and pressure compensation valve 33. Here, the other junction passage 31B is a passage different from the aforementioned junction passage 31A. The other hydraulic device 5 is a hydraulic device different from the first to third hydraulic devices 2 to 4. The other flow control valve 32B and pressure compensation valve 33B are valves different from the flow control valve 32 and pressure compensation valve 33.

[0041] More specifically, separate pump passages 23BL, 23BR, and 23BM branch off from each of the pump passages 23L, 23R, and 23M. A check valve 34BL, 34BR, and 34BM is provided in each of the branched pump passages 23BL, 23BR, and 23BM. A separate junction passage 31B is connected to each of the branched pump passages 23BL, 23BR, and 23BM. A separate pressure compensation valve 33B is provided in the separate junction passage 31B on the side of the junction point 31Ba toward another hydraulic device 5, and the separate junction passage 31B is further connected to another hydraulic device 5 via a separate flow control valve 32B. The hydraulic drive unit 1B of this embodiment also achieves the same effects as the hydraulic drive units 1 and 1A of the first and second embodiments. [Explanation of symbols]

[0042] 1, 1A, 1B Hydraulic drive unit 2. First hydraulic equipment 3. Second hydraulic equipment 4. Third hydraulic equipment 5. Hydraulic equipment 11L First Pump 11R Second Pump 11M 3rd pump 12,12A Multiple control valve block 13,13A Control valve block 21 First directional control valve (first control valve) 22 Second directional control valve (second control valve) 31,31A Merging passage 31a Confluence 32, 32B Flow control valve 33,33B Pressure compensation valve 34L Check valve 34M Check valve 34R check valve

Claims

[Claim 1] A hydraulic drive device that supplies hydraulic fluid to each of a plurality of hydraulic devices including at least first to third hydraulic devices to drive the devices, a plurality of pumps including at least a first pump connected to the first hydraulic device and a second pump connected to the second hydraulic device; a confluence passage connected to the plurality of pumps and confluences hydraulic fluids discharged from the plurality of pumps; a flow control valve connected to the junction passage and the third hydraulic device, the flow control valve adjusting an opening degree in response to an input flow control signal to control the flow rate of hydraulic fluid flowing from the junction passage to the third hydraulic device; a pressure compensation valve that is provided in the junction passage on the third hydraulic device side of a junction point where the hydraulic fluids join, and that maintains a differential pressure before and after the flow control valve at a predetermined pressure; a plurality of check valves provided in the junction passage between the junction point and each of the plurality of pumps, the check valves allowing the flow of hydraulic fluid from each of the pumps to the junction point and preventing the flow of hydraulic fluid in the reverse direction; a multiple control valve block including: a first control valve provided between the first pump and the first hydraulic device, for controlling the flow rate of hydraulic fluid flowing from the first pump to the first hydraulic device; and a second control valve provided between the second pump and the second hydraulic device, for controlling the flow rate of hydraulic fluid flowing from the second pump to the second hydraulic device; a control valve block including the junction passage, the flow control valve, and the pressure compensation valve, the junction passage has a first connection portion connected to the first pump and a second connection portion connected to the first connection portion and the second pump, the plurality of check valves include two check valves interposed in the first connecting portion and two check valves interposed in the second connecting portion, the check valve is interposed in each of the first connection portion and the second connection portion, The hydraulic drive device, wherein the control valve block is separate from the multiple control valve block and attached to the multiple control valve block, and includes the two check valves.

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