Fluid pressure actuated device

Abstract

A fluid pressure driving device is provided. A hydraulic driving device (110) of the present embodiment is provided with a main pump (15) and a single pressure gauge (11). The main pump is a swash plate type variable displacement type and split type hydraulic pump that controls the discharge flow rate of the first working oil and the discharge flow rate of the second working oil that are discharged to a plurality of pressure oil supply paths, the first pressure oil supply path (120) and the second pressure oil supply path (121), using one swash plate (23). The pressure gauge (11) measures the intermediate pressure of the discharged fluid at the merging point (123a) between the first pressure oil supply path (120) and the second pressure oil supply path (121). The discharge flow path is controlled based on the pressure value measured by the pressure gauge (11).

Description

Technical Field

[0001] This invention relates to a fluid pressure driven device. Background Technology

[0002] Pumps used as hydraulic drive devices for construction machinery include so-called diverter pumps with multiple (e.g., 2) ejection ports (see, for example, Patent Document 1).

[0003] However, from the perspective of saving fuel consumption, construction machinery (especially mini excavators) always requires precise control of the pump absorption horsepower of the flow divider pump. As a solution, the following approach is conceived: to precisely control the pump absorption horsepower of the flow divider pump by, for example, electronically digitizing the hydraulic drive device of Patent Document 1.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-61795 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, to make the hydraulic drive unit in the prior art electronic, a pressure gauge would need to be installed at each injection port of the working oil. Therefore, multiple pressure gauges are required, making it difficult to control the cost of the hydraulic drive unit. Consequently, this hydraulic drive unit is not preferred for mini excavators that require inexpensive devices.

[0009] The present invention provides a fluid pressure drive device that can accurately control the pump absorption horsepower of, for example, a split-flow pump and can suppress costs.

[0010] Solution for solving the problem

[0011] One aspect of the fluid pressure drive device of the present invention includes: a fluid pressure pump that uses a ramp to control the ejection flow rate of ejected fluid ejected into a plurality of ejection flow paths; a single pressure detection unit that detects the intermediate pressure of the ejected fluid at the confluence of the plurality of ejection flow paths; and a control unit that controls the ejection flow rate based on the pressure value detected by the pressure detection unit.

[0012] With this configuration, the flow rate of the ejected fluid into multiple ejection paths can be controlled using a single ramp of, for example, a flow divider pump, and the pressure of the ejected fluid at the confluence of the multiple ejection paths can be detected using a single pressure sensor. Therefore, multiple pressure sensors are unnecessary, reducing the cost of the fluid pressure drive device.

[0013] Furthermore, by detecting the pressure of the ejected fluid at the confluence of multiple ejection flow paths, the average pressure is calculated based on the detected pressure value. Moreover, the pump absorption torque can be calculated by aligning the ramp angle, which corresponds to the stroke volume, with the average pressure. Therefore, the maximum pump absorption horsepower can be determined based on the calculated pump absorption torque and, for example, the external environment and engine rotation speed. Consequently, the ejection flow rate can be controlled to the maximum pump absorption horsepower determined by the control unit based on the determined maximum pump absorption horsepower and the ramp angle calculated based on, for example, the average pressure. Thus, by digitizing the hydraulic drive unit, the pump absorption horsepower of the split-flow pump can be controlled with high precision.

[0014] In the above structure, the fluid pump may also include: a cylinder for drawing in and ejecting fluid; and a valve plate for branching the ejected fluid ejected from the cylinder into the plurality of ejection paths.

[0015] In the above structure, the valve plate may also have multiple outlets communicating with each of the plurality of ejection flow paths, and the intermediate pressure may be obtained from the passage that connects the plurality of outlets.

[0016] In the above structure, the fluid pump may also have a housing that houses the cylinder and the valve plate, and the intermediate pressure is obtained from a passage that connects the discharge passages of the housing.

[0017] Another aspect of the fluid pressure drive device of the present invention includes: a fluid pressure pump that uses a ramp to control the ejection flow rate of ejected fluid ejected into a plurality of ejection flow paths; a single pressure detection unit that alternately detects any one of the pressures of the ejected fluid ejected into the plurality of ejection flow paths; and a control unit that controls the ejection flow rate based on the pressure value detected by the pressure detection unit.

[0018] With this configuration, the flow rate of the ejected fluid injected into multiple ejection paths can be controlled using, for example, a swashplate of a flow divider pump, and any one of the pressures of the ejected fluid injected into each of the multiple ejection paths can be detected alternately. Therefore, multiple pressure detection units are unnecessary, reducing the cost of the fluid pressure drive device.

[0019] Furthermore, by alternately detecting the pressure of any one of the ejected fluids injected into multiple ejection paths, the average pressure is calculated based on the detected pressure values. Moreover, the pump absorption torque can be calculated by aligning the swashplate angle, which corresponds to the stroke volume, with the average pressure. Therefore, based on the calculated pump absorption torque, the maximum pump absorption horsepower can be determined according to factors such as the external environment and engine rotation speed. Consequently, based on the determined maximum pump absorption horsepower and the swashplate angle derived from factors such as the average pressure, the ejection flow rate can be controlled to the maximum pump absorption horsepower determined by the control unit. Thus, by digitizing the hydraulic drive unit, the pump absorption horsepower of the split-flow pump can be controlled with high precision.

[0020] In the above structure, the control unit may control the inclined plate based on an average pressure, which is calculated from the pressure detected alternately by the pressure detection unit.

[0021] In the above structure, the pressure of each of the ejected fluids ejected into the plurality of ejection flow paths may also be the high-pressure side piston pressure obtained from the inclined plate side.

[0022] In the above structure, the fluid pump may also include: a cylinder having a cylinder chamber; and a piston movably disposed in the cylinder chamber, which performs fluid intake into the cylinder chamber and fluid ejection from the cylinder chamber, and obtains the high-pressure side piston pressure from the inclined plate via the piston.

[0023] In the above structure, the control unit may determine the maximum absorption horsepower of the pump based on the pressure value detected by the pressure detection unit, and the fluid pressure drive device may include a solenoid valve that is controlled based on the maximum absorption horsepower of the pump.

[0024] In the above structure, the control unit may determine the swashplate angle based on the pump's maximum absorption horsepower, and the solenoid valve may control the swashplate based on the swashplate angle.

[0025] Another aspect of the fluid pressure drive device of the present invention includes: a fluid pressure pump that uses a ramp to control the ejection flow rate of ejected fluid ejected into a plurality of ejection flow paths; a single pressure detection unit that detects the intermediate pressure of the ejected fluid at the confluence of the plurality of ejection flow paths; a control unit that determines the ramp angle based on the pressure value detected by the pressure detection unit; and a solenoid valve that controls the ramp based on the ramp angle.

[0026] With this configuration, the flow rate of the ejected fluid into multiple ejection paths can be controlled using a single ramp of, for example, a flow divider pump, while the pressure of the ejected fluid at the confluence of the multiple ejection paths can be detected using a single pressure sensor. Therefore, multiple pressure sensors are unnecessary, reducing the cost of the fluid pressure drive device.

[0027] Furthermore, by detecting the pressure of the ejected fluid at the confluence of multiple ejection flow paths, the average pressure is calculated based on the detected pressure value. Moreover, the pump absorption torque can be calculated by aligning the ramp angle, which corresponds to the stroke volume, with the average pressure. Therefore, based on the calculated pump absorption torque, the maximum pump absorption horsepower can be determined according to factors such as the external environment and engine rotation speed. Consequently, based on the determined maximum pump absorption horsepower and the ramp angle derived from factors such as the average pressure, the ejection flow rate can be controlled to the maximum pump absorption horsepower determined by the control unit. Thus, by digitizing the hydraulic drive unit, the pump absorption horsepower of the split-flow pump can be controlled with high precision.

[0028] Another aspect of the fluid pressure drive device of the present invention includes: a fluid pressure pump that uses a ramp to control the ejection flow rate of ejected fluid ejected into a plurality of ejection flow paths; a single pressure detection unit that alternately detects any one of the pressures of the ejected fluid ejected into the plurality of ejection flow paths; a control unit that determines the ramp angle based on the pressure value detected by the pressure detection unit; and a solenoid valve that controls the ramp based on the ramp angle.

[0029] With this configuration, the flow rate of the ejected fluid injected into multiple ejection paths can be controlled using, for example, a swashplate of a flow divider pump, and any one of the pressures of the ejected fluid injected into each of the multiple ejection paths can be detected alternately. Therefore, multiple pressure detection units are unnecessary, reducing the cost of the fluid pressure drive device.

[0030] Furthermore, by alternately detecting the pressure of any one of the ejected fluids injected into multiple ejection paths, the average pressure can be calculated based on the detected pressure values, and the pump absorption torque can be calculated by aligning the ramp angle, which corresponds to the stroke volume, with the average pressure. Therefore, based on the calculated pump absorption torque, the maximum pump absorption horsepower can be determined according to factors such as the external environment and engine rotation speed. Consequently, based on the determined maximum pump absorption horsepower and the ramp angle derived from factors such as the average pressure, the ejection flow rate can be controlled to the maximum pump absorption horsepower determined by the control unit. Thus, by digitizing the hydraulic drive unit, the pump absorption horsepower of the split-flow pump can be controlled with high precision.

[0031] The effects of the invention

[0032] According to the aforementioned fluid pressure drive device, the pump absorption horsepower of, for example, a split-type pump can be controlled with high precision, thereby reducing costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the construction machinery in the first embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram showing the hydraulic drive device of the construction machinery according to the first embodiment of the present invention.

[0035] Figure 3 This is a structural diagram showing a portion of the pump unit in the first embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram showing the end face of the cylinder body in the first embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram showing the first end face of the valve plate on the cylinder side in the first embodiment of the present invention.

[0038] Figure 6 This is an enlarged cross-sectional view of the main part of the hydraulic drive device according to the second embodiment of the present invention.

[0039] Figure 7 This is a schematic diagram showing the hydraulic drive device according to the third embodiment of the present invention.

[0040] Figure 8 This is an enlarged cross-sectional view of the main part of the hydraulic drive device according to the third embodiment of the present invention.

[0041] Figure 9 This is a schematic diagram showing the end face of the cylinder body in the third embodiment of the present invention.

[0042] Figure 10 This is a schematic diagram showing the first end face of the valve plate on the cylinder side in the third embodiment of the present invention.

[0043] Figure 11 This is a schematic diagram showing the main parts of the hydraulic drive device according to the fourth embodiment of the present invention.

[0044] Figure 12 It is a perspective view formed by disassembling the front flange and the inclined plate in the fourth embodiment.

[0045] Figure 13 This is a side view of the front flange and the inclined plate in the fourth embodiment.

[0046] Explanation of reference numerals in the attached figures

[0047] 11. Pressure gauge (pressure detection unit); 12. Control unit; 13. Electromagnetic proportional valve (solenoid valve); 15. Main pump (fluid pump); 22. Cylinder body (an example of the cylinder of the claim); 23. Inclined plate; 43b. Outer peripheral side outlet (outlet); 43c. Inner peripheral side outlet (outlet); 44a, 44b. Third connecting path, fourth connecting path (ejection flow path, discharge passage); 68. Cylinder chamber; 71. Piston; 110, 140, 150, 160. Hydraulic Drive unit (fluid pressure drive unit); 120, first pressure oil supply path (ejection flow path); 121, second pressure oil supply path (ejection flow path); 123, metering connection path; 123a, merging part; 141, metering connection path (passage connecting multiple outlets of the valve plate; passage connecting various discharge passages of the housing); P1, P2, ejection pressure; P1, P2, intermediate pressure (pressure after merging); P1, P2, ejection pressure (high pressure side piston pressure). Detailed Implementation

[0048] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0049] [First Implementation]

[0050] <Construction Machinery>

[0051] Figure 1 This is a schematic diagram of the construction machinery 100 in the first embodiment.

[0052] like Figure 1 As shown, the construction machinery 100 is, for example, a hydraulic excavator. The construction machinery 100 includes a rotating body 101 and a traveling body 102. The rotating body 101 rotates on top of the traveling body 102. The rotating body 101 includes a hydraulic drive device (an example of the fluid pressure drive device of the claim) 110.

[0053] The slewing body 101 includes a cab 103, a boom 104, a stick 105, and a bucket 106. The cab 103 supports an operator riding in the slewing body 101. One end of the boom 104 is connected to the main body of the slewing body 101. The boom 104 swings relative to the main body of the slewing body 101. One end of the stick 105 is connected to the other end (top) of the boom 104 on the opposite side of the main body of the slewing body 101. The stick 105 swings relative to the boom 104. The bucket 106 is connected to the other end (top) of the stick 105 on the opposite side of the boom 104. The bucket 106 swings relative to the stick 105.

[0054] The hydraulic drive unit 110 is located, for example, inside the cab 103. Working oil (working fluid) supplied from the hydraulic drive unit 110 drives the cab 103, boom 104, stick 105, and bucket 106.

[0055] <Hydraulic drive unit>

[0056] Figure 2 This is a schematic diagram of the hydraulic drive unit 110 of the construction machinery 100.

[0057] like Figure 2 As shown, the hydraulic drive unit 110 includes a power source 1, a pump unit 2, multiple actuators 3a to 3d, a control valve 4, multiple pilot valves 5a to 5d, and a torque control unit 6.

[0058] The torque control unit 6 includes a pressure gauge (an example of the pressure detection unit of the claim) 11, a control unit 12, an electromagnetic proportional valve (an example of the electromagnetic valve of the claim) 13, and a swashplate control actuator 14.

[0059] Power source 1 is, for example, a diesel engine (hereinafter referred to as engine 1).

[0060] <Pump Unit>

[0061] Figure 3 This is a structural diagram showing a portion of the section pump unit 2. Figure 3 The section shown along the axial direction represents only the main pump 15. Figure 3 In order to make the explanation easier to understand, the scale of each component has been appropriately changed.

[0062] like Figure 2 , Figure 3 As shown, pump unit 2 is a so-called hydraulic pump that draws in and injects working oil. Pump unit 2 has an integrated main pump (an example of the fluid pressure pump of the claims) 15 and a pilot pump 16 as an auxiliary pump. The main pump 15 and the pilot pump 16 are connected in series with the drive shaft 18 of the engine 1 and are driven by the engine 1.

[0063] <Main Pump>

[0064] The main pump 15 is a so-called swashplate-type variable capacity and diverter type hydraulic pump. The main pump 15 mainly comprises a main housing 20, a shaft 21, a cylinder (an example of the cylinder of the claim) 22, and a swashplate 23. The shaft 21 rotates about a central axis C relative to the main housing 20. The cylinder 22 is housed within the main housing 20 and fixed to the shaft 21. The swashplate 23 is housed within the main housing 20 and rotates relative to the main housing 20, thereby controlling the discharge rate of working oil from the main pump 15.

[0065] In the following description, the direction parallel to the central axis C of shaft 21 is called the axial direction, the direction of rotation of shaft 21 is called the circumferential direction, and the radial direction of shaft 21 is simply referred to as the radial direction.

[0066] The main housing 20 includes: a box-shaped housing body 25 having an opening 25a; and a front flange 26 that blocks the opening 25a of the housing body 25.

[0067] The housing body 25 has a bottom wall 28 on the side opposite to the opening 25a. The cylinder 22 is disposed on the inner surface 28a side of the bottom wall 28. The pilot pump 16 is mounted on the outer surface 28b of the bottom wall 28.

[0068] A rotating shaft through hole 29 is formed in the bottom wall 28 in such a way that it extends through the thickness of the bottom wall 28, through which the shaft 21 can pass. A rotatable bearing 31 supporting one end of the shaft 21 is provided near the inner surface 28a of the bottom wall 28 (on the side opposite to the opening 25a). The bottom wall 28 is the wall portion of the housing body 25 located on the central axis C of the shaft 21.

[0069] On the bottom wall 28, a first suction path 32, a first discharge path 33a, and a second discharge path 33b are formed radially on both sides, separated by the shaft 21. The first suction path 32 communicates with a suction port 32a formed on the first side 28c of the bottom wall 28. The suction port 32a communicates with the tank 35. The first suction path 32 extends within the bottom wall 28 in such a way that the opening area gradually decreases from the first side 28c toward the shaft 21.

[0070] An O-ring groove 38 is formed on the outer surface 28b of the bottom wall 28 in a manner that surrounds the through hole 29 of the rotating shaft and the second communication path 37. An O-ring 39 is installed and fixed in the O-ring groove 38. The O-ring 39 ensures a tight seal between the main housing 20 and the gear housing 81 of the pilot pump 16 (described later).

[0071] Based on this structure, the working oil is drawn from tank 35 into the first suction path 32 via suction port 32a. The working oil drawn into the first suction path 32 flows into the first connecting path 36 and the second connecting path 37.

[0072] At the outlet of the first discharge path 33a, a first ejection port 41 is formed on a second side 28d, located opposite the first side 28c of the bottom wall 28 and separated by shaft 21. Similarly, at the outlet of the second discharge path 33b, a second ejection port 42 is formed on a second side 28d, located opposite the first side 28c of the bottom wall 28 and separated by shaft 21. The first ejection port 41 and the second ejection port 42 are connected to actuators 3a to 3d via control valves 4 and the like.

[0073] The first discharge path 33a and the second discharge path 33b extend from the second side 28d toward the shaft 21 within the bottom wall 28. A third connecting path (an example of the ejection flow path or discharge passage of the claim) 44a is formed at the shaft 21-side end of the first discharge path 33a, connecting the first discharge path 33a to the inner surface 28a of the bottom wall 28. The third connecting path 44a connects the first discharge path 33a to the outer peripheral discharge port 43b of the valve plate 43, which will be described later.

[0074] A fourth connecting path (an example of the ejection flow path or discharge passage of the claim) 44b is formed at the end of the second discharge path 33b on the side near the shaft 21, connecting the second discharge path 33b and the inner surface 28a of the bottom wall 28. The fourth connecting path 44b connects the second discharge path 33b and the inner peripheral discharge port 43c of the valve plate 43 described later.

[0075] A through hole 46 is formed in the front flange 26 through which the shaft 21 can pass. A bearing 47, which supports the other end of the shaft 21 and allows it to rotate freely, is provided in the through hole 46. An oil seal 48 is provided in the portion of the through hole 46 located on the side opposite to the housing body 25 (outside the front flange 26) to the bearing 47.

[0076] Used to fix the main pump 15 to the rotating body 101 (see reference) Figure 1 The two mounting plates 49 are integrally formed with the front flange 26. The two mounting plates 49 are arranged on both sides radially apart from the shaft 21. The mounting plates 49 extend radially outward.

[0077] Shaft 21 is stepped. Shaft 21 includes a rotating shaft body 51, a first bearing portion 52, a transmission shaft 53, a second bearing portion 54, and a connecting shaft 55, all arranged coaxially. The rotating shaft body 51 is disposed within the main housing 20. The first bearing portion 52 is integrally formed with the end of the rotating shaft body 51 on the side facing the bottom wall 28 of the housing body 25. The transmission shaft 53 is integrally formed with the end of the first bearing portion 52 on the side opposite to the rotating shaft body 51. The second bearing portion 54 is integrally formed with the end of the rotating shaft body 51 on the side facing the front flange 26. The connecting shaft 55 is integrally formed with the end of the second bearing portion 54 on the side opposite to the rotating shaft body 51.

[0078] A second spline 51a is formed on the rotating shaft body 51. The cylinder body 22 engages with the second spline 51a of the rotating shaft body 51. The shaft diameter of the first bearing portion 52 is smaller than the shaft diameter of the rotating shaft body 51. The first bearing portion 52 is rotatably supported by a bearing 31 on the bottom wall 28.

[0079] The transmission shaft 53 transmits the rotational force of the shaft 21 to the pilot pump 16. The shaft diameter of the transmission shaft 53 is smaller than the shaft diameter of the first bearing portion 52. The transmission shaft 53 protrudes towards the pilot pump 16 via the bearing 31. The transmission shaft 53 is disposed within the rotating shaft through hole 29 of the bottom wall 28. A cylindrical coupling 57 is fitted onto the outer circumferential surface of the transmission shaft 53. The coupling 57 rotates integrally with the transmission shaft 53. The pilot pump 16 side of the coupling 57 protrudes towards the pilot pump 16 relative to the bottom wall 28. The protruding portion of the coupling 57 on the pilot pump 16 side is connected to the pilot pump 16.

[0080] The shaft diameter of the second bearing portion 54 is larger than that of the first bearing portion 52. The second bearing portion 54 is rotatably supported on the bearing 47 of the front flange 26.

[0081] The connecting shaft 55 is connected to the drive shaft 18 of the engine 1. The shaft diameter of the connecting shaft 55 is smaller than the shaft diameter of the second bearing portion 54. The top end of the connecting shaft 55 protrudes outward from the front flange 26 via the bearing 47. The oil seal 48 prevents working oil from flowing out from the inside and prevents foreign objects from entering between the top end of the connecting shaft 55 and the front flange 26. A first spline 55a is formed at the top end of the connecting shaft 55. The drive shaft 18 and shaft 21 of the engine 1 are connected by the first spline 55a.

[0082] Figure 4 This is a schematic diagram showing the end face 22A of the end portion 22a in the cylinder block 22.

[0083] like Figure 3 and Figure 4 As shown, the cylinder body 22 is cylindrical. A through hole 61 is formed in the radial center of the cylinder body 22, into which a shaft 21 can be inserted or pressed. A spline 61a is formed on the inner wall surface of the through hole 61. The spline 61a engages with the second spline 51a of the rotating shaft body 51. The shaft 21 and the cylinder body 22 rotate integrally by means of the splines 61a and 51a. The cylinder body 22 is axially supported by the hydrostatic pressure of the working oil between it and the valve plate 43 (described later).

[0084] On the cylinder body 22, a recess 63 is formed around the shaft 21 between the axial center of the through hole 61 and the end 22a on the side of the bottom wall 28. A through hole 64, axially penetrating the cylinder body 22, is formed on a portion of the inner wall surface between the axial center of the through hole 61 and the front flange 26 side. A spring 65 and seat rings 66a and 66b are housed in the recess 63. A connecting member 67 is housed in the through hole 64 in a manner that allows axial movement.

[0085] A plurality of cylinder chambers 68 are formed on the cylinder block 22 in a manner surrounding the shaft 21. The plurality of cylinder chambers 68 are arranged at equal intervals along a predetermined pitch circle concentric with the central axis C. The cylinder chambers 68 are formed as bottomed cylindrical shapes extending axially. The front flange 26 side of the cylinder chamber 68 is open, and the bottom wall 28 side of the cylinder chamber 68 is closed. At the end 22a of the cylinder block 22, at positions corresponding to each cylinder chamber 68, an outer peripheral communication hole 69a or an inner peripheral communication hole 69b is formed to communicate between each cylinder chamber 68 and the outside of the cylinder block 22.

[0086] Figure 5 This is a schematic diagram showing the end face (first end face) 43A of the valve plate 43 on the side near the cylinder body 22.

[0087] like Figures 3-5 As shown, the valve plate 43 is formed in the shape of a circular plate. The valve plate 43 is disposed between the end face 22A of the end 22a of the cylinder body 22 and the inner surface 28a of the bottom wall 28 of the housing body 25. The valve plate 43 is fixed to the bottom wall 28 of the housing body 25. Even when the cylinder body 22 and the shaft 21 rotate about the central axis C, the valve plate 43 remains stationary relative to the housing body 25.

[0088] On the valve plate 43, a supply port 43a is formed in a manner that extends through the thickness direction of the valve plate 43 and communicates with each of the outer peripheral communication holes 69a and each of the inner peripheral communication holes 69b of the cylinder body 22. The shape of the supply port 43a is, for example, formed as an arc-shaped elongated hole within a predetermined angle range around the central axis C.

[0089] The first communication path 36 formed by each cylinder chamber 68 and the housing body 25 is connected by the supply port 43a of the valve plate 43 and the outer peripheral communication hole 69a or inner peripheral communication hole 69b of the cylinder body 22.

[0090] The valve plate 43 has: a plurality of outer peripheral outlets (an example of the outlets in the claim) 43b, which communicate with each outer peripheral connecting hole 69a of the cylinder body 22; and a plurality of inner peripheral outlets (an example of the outlets in the claim) 43c, which communicate with each inner peripheral connecting hole 69b of the cylinder body 22 and are located radially inward of the outer peripheral outlets 43b. Each connecting hole 69a, 69b is formed to extend through the valve plate 43 in the thickness direction. The outer peripheral outlets 43b and inner peripheral outlets 43c are each formed, for example, as elongated arc-shaped holes within a predetermined angle range around the central axis C.

[0091] Multiple peripheral outlets 43b are formed on the first end face 43A on a first segment circle concentric with the central axis C. The multiple peripheral outlets 43b are formed on the first end face 43A to communicate with the arc-shaped peripheral recess 45a formed on the first segment circle.

[0092] Multiple inner peripheral side outlets 43c are formed on the first end face 43A on a second segment circle that is smaller than the first segment circle concentric with the central axis C. The multiple inner peripheral side outlets 43c are formed on the first end face 43A to communicate with the arc-shaped inner peripheral side recess 45b formed on the second segment circle.

[0093] The diameter of the first pitch circle is closer to the diameter of the predetermined pitch circle for the plurality of cylinder chambers 68 of the cylinder block 22 than the diameter of the second pitch circle. The diameter of the first pitch circle is, for example, set to be slightly smaller than the diameter of the predetermined pitch circle for the plurality of cylinder chambers 68.

[0094] Each cylinder chamber 68 and the third communication path 44a formed in the housing body 25 are connected via the outer peripheral outlet 43b of the valve plate 43 and the outer peripheral communication hole 69a of the cylinder body 22.

[0095] Each cylinder chamber 68 and the fourth communication path 44b formed in the housing body 25 are connected via the inner peripheral side outlet 43c of the valve plate 43 and the inner peripheral side communication hole 69b of the cylinder body 22.

[0096] The valve plate 43 is fixed to the housing body 25. Therefore, each cylinder chamber 68 switches between a state where working oil is supplied from the first suction path 32 via the valve plate 43 and a state where working oil is sprayed into the first discharge path 33a or the second discharge path 33b, depending on the rotation state of the cylinder body 22.

[0097] The piston 71 is housed in each of the cylinder chambers 68 of the cylinder body 22, so that as the shaft 21 and the cylinder body 22 rotate, the piston 71 rotates in a manner that revolves around the central axis C of the shaft 21.

[0098] The piston 71 has an integrally formed spherical protrusion 72 at the end near the front flange 26. A recess 73 is formed inside the piston 71 to collect working oil from the cylinder chamber 68. The reciprocating motion of the piston 71 is related to the supply and discharge of working oil relative to the cylinder chamber 68.

[0099] As the piston 71 is pulled out of the cylinder chamber 68, working oil is supplied into the cylinder chamber 68 from the first intake path 32 via the first communication path 36 and the supply port 43a.

[0100] As the piston 71 enters the cylinder chamber 68, working oil is discharged from the cylinder chamber 68 through the outer peripheral side connecting hole 69a, the outer peripheral side discharge port 43b, the third connecting path 44a, and the first discharge path 33a. Additionally, working oil is discharged from the cylinder chamber 68 through the inner peripheral side connecting hole 69b, the inner peripheral side discharge port 43c, the fourth connecting path 44b, and the second discharge path 33b.

[0101] The spring 65 housed in the recess 63 of the cylinder body 22 is, for example, a coil spring. The spring 65 is compressed between two races 66a and 66b housed in the recess 63. The spring 65 utilizes elastic force to generate a force in the direction of extension. The force of the spring 65 is transmitted to the connecting member 67 via one of the races 66a and 66b. The force of the spring 65 is transmitted to the pushing member 75 via the connecting member 67. The pushing member 75 engages with the outer peripheral surface of the rotating shaft body 51 at a position closer to the front flange 26 than the connecting member 67.

[0102] A ramp 23 is disposed on the inner surface 26a of the front flange 26 on the side near the housing body 25. The ramp 23 is tiltable relative to the front flange 26. By tilting the ramp 23 relative to the front flange 26, the axial displacement of each piston 71 is restricted. A through hole 76 for a shaft 21 to pass through is formed in the radial center of the ramp 23. The ramp 23 has a flat sliding surface 23a on the cylinder body 22 side.

[0103] Multiple sliding shoes 77 movable on the sliding surface 23a are mounted on the protrusion 72 of the piston 71. A spherical recess 77a is formed on the side of the sliding shoe 77 that receives the protrusion 72, corresponding to the shape of the protrusion 72. The protrusion 72 of the piston 71 is embedded in the inner wall surface of the recess 77a. The sliding shoe 77 is connected to the protrusion 72 of the piston 71 in a manner that allows it to rotate relative to the protrusion 72 of the piston 71.

[0104] The shoe retaining member 78 integrally holds each shoe 77. The pushing member 75 contacts the shoe retaining member 78 and pushes the shoe retaining member 78 toward the inclined plate 23. The shoe 77 moves in a manner that follows the sliding surface 23a of the inclined plate 23. The inclined plate angle of the inclined plate 23 is controlled by the inclined plate control actuator 14 (see reference). Figure 2 )control.

[0105] As described above, the main pump 15 includes: a single swashplate 23 that controls the amount of working oil injected from the cylinder 22; and a valve plate 43 that branches the working oil injected from the cylinder 22 into multiple portions. The amount of working oil injected from the first injection port 41 and the second injection port 42 of the main pump 15 is controlled by the single swashplate 23.

[0106] That is, the main pump 15 is controlled by using the swashplate control actuator 14 to change the swashplate angle of a single swashplate 23, thereby changing the push-out amount (push-out volume) and causing the ejection flow rate from the first ejection port 41 and the second ejection port 42 to change.

[0107] <Pilot Pump>

[0108] A first connecting path 36 is formed at the end of the first suction path 32 on the side near the shaft 21, connecting the first suction path 32 and the inner surface 28a of the bottom wall 28. The first connecting path 36 connects the first suction path 32 and the supply port 43a of the valve plate 43.

[0109] A second connecting path 37 is formed at the end of the first suction path 32 on the side near the shaft 21, connecting the first suction path 32 and the outer surface 28b of the bottom wall 28. The second connecting path 37 connects the first suction path 32 and the second suction path 82 of the pilot pump 16, which will be described later.

[0110] The pilot pump 16 is, for example, a gear pump, which includes a gear housing 81 and a drive gear and a driven gear (not shown).

[0111] A cuboid gear housing 81 is disposed on the outer surface 28b of the bottom wall 28 of the main housing 20. A second intake path 82 is formed on the wall surface 81a of the gear housing 81 that overlaps with the main housing 20, communicating with the second communication path 37 of the main housing 20. The second intake path 82 connects the inside and outside of the wall surface 81a of the gear housing 81.

[0112] On the wall surface 81a of the gear housing 81, a coupling through hole 83 is formed at a position corresponding to the rotating shaft through hole 29 of the main housing 20. The end of the coupling 57 on the side of the pilot pump 16 protrudes into the gear housing 81 through the coupling through hole 83.

[0113] The first side wall 81b of the gear housing 81 faces the same direction as the first side wall 28c of the main housing 20, which has an intake port 32a. The second side wall 81c faces the same direction as the second side wall 28d of the main housing 20, which has an outlet with a first discharge path 33a and an outlet with a second discharge path 33b.

[0114] like Figure 2 and Figure 3 As shown, a third discharge path (not shown) is formed on the second side wall 81c of the gear housing 81. The third discharge path of the gear housing 81 opens on the second side wall 81c. The outlet of the third discharge path of the gear housing 81, the outlet of the first discharge path 33a of the main housing 20, and the outlet of the second discharge path 33b are formed on the second side wall 81c and the second side surface 28d facing the same direction. A third ejection port 59 is formed at the outlet of the third discharge path. That is, the third ejection port 59 is arranged in the same direction as the first ejection port 41 and the second ejection port 42.

[0115] The drive gear and driven gear of the pilot pump 16 are rotatably supported within the gear housing 81 and mesh with each other. The drive gear is connected to a coupling 57 protruding from the main housing 20 via a coupling through-hole 83. The rotational force of the shaft 21 in the main pump 15 is transmitted to the drive gear via the coupling 57. The driven gear meshes with the drive gear and therefore rotates synchronously with it.

[0116] like Figure 1 , Figure 2 As shown, a plurality of actuators 3a to 3d are connected to the first ejection port 41 and the second ejection port 42 via control valves 4, etc. The plurality of actuators 3a to 3d are driven by a first working oil (a first pressure oil, an example of the ejection fluid of the claim) ejected from the first ejection port 41 of the main pump 15 and a second working oil (a second pressure oil, an example of the ejection fluid of the claim) ejected from the second ejection port 42.

[0117] Actuator 3a is, for example, a hydraulic motor that rotates the slewing body 101. Actuator 3b is, for example, a hydraulic cylinder that swings the boom 104. Actuator 3c is, for example, a hydraulic cylinder that swings the stick 105. Actuator 3d is, for example, a hydraulic cylinder that swings the bucket 106.

[0118] Control valve 4 is connected to the first ejection port 41 and the second ejection port 42 of the main pump 15 via a first pressure oil supply path (an example of the ejection flow path of the claim) 120 and a second pressure oil supply path (an example of the ejection flow path of the claim) 121. Control valve 4 incorporates a plurality of neutral-opening flow control valves 15a to 15d. The plurality of flow control valves 15a to 15d control the flow rates of the first and second working oil supplied from the first ejection port 41 and the second ejection port 42 to the plurality of actuators 3a to 3d.

[0119] Multiple pilot valves 5a to 5d are connected to the third discharge port 59 of the pilot pump 16 via the third pressure oil supply path 122. The multiple pilot valves 5a to 5d use the third working oil (third pressure oil) ejected from the third discharge port 59 of the pilot pump 16 to generate the operating pilot pressure for controlling the multiple flow control valves 15a to 15d.

[0120] Multiple pilot valves 5a to 5d are equipped with operating levers (not shown). The multiple pilot valves 5a to 5d are selectively operated according to the operating direction of each operating lever, so that the third pressure oil (the ejection pressure of the pilot pump 16) in the third pressure oil supply path 122 is used as the initial pressure to generate a pilot pressure corresponding to the operating amount of the operating lever.

[0121] The pilot pressure is output to the corresponding flow control valves 15a to 15d in the control valve 4 via the pilot oil circuit, so as to perform the switching operation of the flow control valves 15a to 15d.

[0122] When the bucket 106 is oscillated by the hydraulic cylinder of actuator 3d, for example, the second working pressure (second pressure oil) guided from the second ejection port 42 of the main pump 15 to the second pressure oil supply path 121 is transmitted to actuator 3d. On the other hand, the first working pressure (first pressure oil) guided from the first ejection port 41 of the main pump 15 to the first pressure oil supply path 120 is returned to tank 35.

[0123] The first pressure oil supply path 120 and the second pressure oil supply path 121 are connected by a metering connection path 123. The metering connection path 123 has a first throttling orifice 124 at its connection to the first pressure oil supply path 120 and a second throttling orifice 125 at its connection to the second pressure oil supply path 121. A single pressure gauge 11 is connected to the portion of the metering connection path 123 between the first throttling orifice 124 and the second throttling orifice 125 via a pressure metering path 126. A third throttling orifice 132 is provided in the pressure metering path 126. Alternatively, the third throttling orifice 132 may not be provided in the pressure metering path 126.

[0124] First working oil is ejected from the first ejection port 41 of the main pump 15 into the first pressure oil supply path 120, and second working oil is ejected from the second ejection port 42 of the main pump 15 into the second pressure oil supply path 121. The first working oil is guided through the first throttling orifice 124 of the metering connection path 123 to the confluence portion 123a of the metering connection path 123 (an example of the confluence portion of the claim). The second working oil is guided through the second throttling orifice 125 of the metering connection path 123 to the confluence portion 123a of the metering connection path 123.

[0125] The first working oil and the second working oil merge at the confluence point 123a. After merging, the first working oil and the second working oil are guided to the pressure gauge 11 of the torque control unit 6 via the pressure metering path 126.

[0126] <Torque Control Unit>

[0127] The pressure gauge 11, control unit 12, electromagnetic proportional valve 13, and swashplate control actuator 14 constituting the torque control unit 6 will be described below.

[0128] After merging at the confluence point 123a, the first and second working oils are guided to the pressure measurement path 126. The pressure gauge 11 measures (an example of the detection according to the claim) the pressure of the merged first and second working oils (an example of the pressure after merging according to the claim) as a pressure value. Hereinafter, the pressure of the merged first and second working oils is sometimes referred to as the "intermediate pressure". The pressure value measured by the pressure gauge 11 is transmitted to the control unit 12 as an electrical signal.

[0129] In the first embodiment, a pressure sensing unit is exemplified by a device that mechanically measures pressure (i.e., pressure gauge 11), but it is not limited to this. As other examples, a pressure sensing unit such as a pressure sensor that electrically measures pressure using a strain gauge may also be used.

[0130] The control unit 12 calculates the average pressure based on the transmitted pressure value, and calculates the pump absorption torque based on the average pressure. Furthermore, based on the calculated pump absorption torque, the control unit 12 determines the pump's maximum absorption horsepower (i.e., the swashplate angle of the swashplate 23) according to factors such as the external environment and the rotational speed of the engine 1. Additionally, the control unit 12 transmits the determined swashplate angle of the swashplate 23 as an electrical signal to the solenoid proportional valve 13.

[0131] The electromagnetic proportional valve 13 operates the swashplate control actuator 14 based on the swashplate angle of the swashplate 23 determined by the control unit 12.

[0132] Specifically, the input port 127 of the electromagnetic proportional valve 13 is connected to the third pressure oil supply path 122 via the first pilot passage 128, and the output port 129 is connected to the swashplate control actuator 14 via the second pilot passage 130. The third working oil ejected from the pilot pump 16 is transmitted to the input port 127 via the third pressure oil supply path 122 and the first pilot passage 128.

[0133] In addition, the electromagnetic proportional valve 13 operates, thereby transmitting the third working oil (pilot oil) delivered to the input port 127 from the output port 129 to the swashplate control actuator 14 via the second pilot passage 130.

[0134] The electromagnetic proportional valve 13 operates based on the swashplate angle of the swashplate 23 determined by the control unit 12, thereby enabling the transmission of pilot oil from the third working oil ejected from the pilot pump 16 to the swashplate control actuator 14.

[0135] The swashplate control actuator 14 operates based on pilot oil transmitted from the electromagnetic proportional valve 13, such as a piston forward and backward control cylinder (not shown). When the swashplate control actuator 14 operates, the swashplate 23 is controlled to the swashplate angle determined by the control unit 12.

[0136] <Operation of the hydraulic drive unit>

[0137] Next, the operation of the hydraulic drive device 110 will be explained.

[0138] First working oil is ejected from the first ejection port 41 of the main pump 15 into the first pressure oil supply path 120, and the ejected first working oil passes through the first throttle orifice 124. In addition, second working oil is ejected from the second ejection port 42 of the main pump 15 into the second pressure oil supply path 121, and the ejected second working oil passes through the second throttle orifice 125.

[0139] The first working oil and the second working oil merge at the confluence point 123a between the first throttling orifice 124 and the second throttling orifice 125 in the metering connection path 123. The merged working oil is then transmitted to the pressure gauge 11 via the pressure metering path 126. The pressure gauge 11 is used to detect the intermediate pressures P1 and P2 of the merged first and second working oils.

[0140] The intermediate pressure P1 is the intermediate pressure of the first working oil as the main component in the first and second working oils after merging.

[0141] The intermediate pressure P2 is the intermediate pressure of the first working oil and the second working oil after merging, with the second working oil as the main component.

[0142] The pressure waveforms of intermediate pressure P1 and intermediate pressure P2 change regularly.

[0143] The intermediate pressures P1 and P2 detected by the pressure gauge 11 are electrically transmitted to the control unit 12.

[0144] In the control unit 12, the average pressure Pm = (P1 + P2) / 2 is calculated based on the intermediate pressures P1 and P2 measured by the pressure gauge 11, and the intermediate pressures (P1 and P2) are averaged.

[0145] When the following settings are made,

[0146] That is, the pump absorbs torque: the torque used to drive the main pump 15.

[0147] V1: The opening amount of the first ejection port 41 of the main pump 15

[0148] V2: The amount of thrust at the second ejection port 42 of the main pump 15

[0149] η: Efficiency

[0150] Based on the calculated average pressure Pm, the pump absorption torque is calculated as Pm×(V1+V2) / (2π×η).

[0151] Based on the calculated pump absorption torque, the sloping angle of the sloping plate 23 is determined to be V1 + V2. Furthermore, the control unit 12 determines the maximum pump absorption horsepower based on the external environment and the rotational speed of the engine 1.

[0152] The control unit 12 transmits an electrical signal to the electromagnetic proportional valve 13 based on the information determined by the control unit 12. The electromagnetic proportional valve 13 operates based on the transmitted electrical signal. As the electromagnetic proportional valve 13 operates, the pilot oil injected from the pilot pump 16 is transmitted to the swashplate control actuator 14 based on the swashplate angle of the swashplate 23 determined by the control unit 12.

[0153] The swashplate control actuator 14 operates based on pilot oil transmitted from the solenoid proportional valve 13, causing a piston (not shown) to move forward and backward. As the swashplate control actuator 14 operates, the swashplate 23 is controlled to the swashplate angle determined by the control unit 12. Thus, by using the solenoid proportional valve 13 to control the swashplate angle of the swashplate 23, precise control is possible for functions such as horsepower control, full horsepower control, air conditioning control, and other horsepower reduction controls.

[0154] As explained above, in the hydraulic drive device 110 according to the first embodiment, the main pump 15 is a split-flow pump, which branches the working oil ejected from the cylinder 22 into multiple working oils, namely a first working oil and a second working oil, using a valve plate 43. The multiple first and second working oils branched by the valve plate 43 are then combined, and the intermediate pressures P1 and P2 of the combined first and second working oils can be measured using a single pressure gauge 11. Therefore, multiple pressure gauges are unnecessary, reducing the cost of the hydraulic drive device 110.

[0155] Furthermore, by using a single pressure gauge 11 to measure the intermediate pressures P1 and P2 of the first and second working oils after merging, for example, the control unit 12 calculates the average pressure based on the measured pressure values. Moreover, the control unit 12 can calculate the pump absorption torque by aligning the swashplate angle, which corresponds to the stroke volume, with the average pressure. Therefore, the control unit 12 can determine the pump's maximum absorption horsepower (i.e., the swashplate angle of the swashplate 23) based on the calculated pump absorption torque and, for example, the external environment and the rotational speed of the engine 1.

[0156] Therefore, the ejection flow rate can be controlled to the maximum pump absorption horsepower determined by the control unit 12, and based on the swashplate angle calculated from, for example, the average pressure. Thus, by providing an electromagnetic proportional valve 13 in the torque control unit 6, the swashplate angle of the swashplate 23 can be electronically controlled, and the pump absorption horsepower of the split-type main pump 15 can be controlled with high precision.

[0157] The intermediate pressures P1 and P2 of the working oil after merging change regularly. Therefore, by using pressure gauge 11 to detect the intermediate pressures P1 and P2, the rotational speed of the main pump 15 can be detected based on the peak values ​​in the pressure waveforms of the intermediate pressures P1 and P2.

[0158] In the first embodiment described above, an example of branching the working oil sprayed from the cylinder 22 into a first working oil and a second working oil using the valve plate 43 was given, but the embodiment is not limited to this. As another example, the working oil sprayed from the cylinder 22 may be branched into three or more working oils using the valve plate 43.

[0159] The following is based on Figures 6 to 13 The hydraulic drive devices 140, 150, and 160 of the second to fourth embodiments are described. In the second to fourth embodiments, components that are the same as or similar to the hydraulic drive device 110 of the first embodiment are labeled with the same reference numerals, and detailed descriptions are omitted.

[0160] [Second Implementation]

[0161] Figure 6 This is an enlarged cross-sectional view of the main part of the hydraulic drive device 140 of the second embodiment (an example of the fluid pressure drive device of the claim).

[0162] like Figure 2 and Figure 6 As shown, the hydraulic drive unit 140 has a metering connection path 141 (an example of the passage connecting the multiple outlets of the valve plate and the various discharge passages of the housing) 141 on the bottom wall 28 of the housing body 25. The metering connection path 141 is connected to a single pressure gauge 11 via a pressure metering path 142.

[0163] Specifically, a third connecting path 44a and a fourth connecting path 44b are formed on the bottom wall 28 of the housing body 25. A first working oil branching off from the valve plate 43 is guided into the third connecting path 44a. A second working oil branching off from the valve plate 43 is guided into the fourth connecting path 44b.

[0164] The middle of the third connecting path 44a and the middle of the fourth connecting path 44b are connected by the metering connecting path 141. That is, the outer peripheral discharge outlet 43b and the inner peripheral discharge outlet 43c are connected by the metering connecting path 141 via the third connecting path 44a and the fourth connecting path 44b.

[0165] The metering connection path 141 extends radially. In the metering connection path 141, a first throttling orifice 143 is provided at the location connecting to the third connection path 44a, and a second throttling orifice 144 is provided at the location connecting to the third connection path 44a. A single pressure gauge 11 is connected to the portion of the metering connection path 141 located between the first throttling orifice 143 and the second throttling orifice 144 via a pressure metering path 142. A third throttling orifice 145 is provided in the pressure metering path 142. Alternatively, the third throttling orifice 145 may not be provided in the pressure metering path 142.

[0166] As explained above, the hydraulic drive device 140 according to the second embodiment, and Figure 2 Similarly, in the hydraulic drive device 110 of the first embodiment shown, the working oil sprayed from the cylinder 22 is branched into multiple working oils, namely a first working oil and a second working oil, by means of a valve plate 43. By means of the valve plate 43, the multiple first working oils and second working oils are branched into a single flow, and the intermediate pressure (P1, P2) of the combined first working oil and second working oil can be measured by a single pressure gauge 11.

[0167] Therefore, for example, the control unit 12 can calculate the average pressure based on the measured pressure value, and the control unit 12 can calculate the pump absorption torque based on the average pressure. As a result, the control unit 12 can determine the pump's maximum absorption horsepower (i.e., the swashplate angle of the swashplate 23) based on the calculated pump absorption torque and, for example, the external environment and the rotational speed of the engine 1.

[0168] Therefore, based on the maximum pump absorption horsepower determined by the control unit 12, the swashplate control actuator 14 can be operated using, for example, an electromagnetic proportional valve 13, to control the swashplate 23 to the swashplate angle determined by the control unit 12, thereby controlling the ejection flow rate. Thus, by providing an electromagnetic proportional valve 13 in the torque control unit 6, the swashplate angle of the swashplate 23 can be electronically controlled, enabling precise control of the pump absorption horsepower of the split-type main pump 15.

[0169] Furthermore, the intermediate pressures P1 and P2 of the first and second working oils after merging can be measured using a single pressure gauge 11. Therefore, it is unnecessary to have multiple pressure gauges, and similarly to the hydraulic drive device 110 of the first embodiment, the cost of the hydraulic drive device 140 can be reduced.

[0170] Furthermore, by providing a metering communication path 141 on the bottom wall 28 of the housing body 25, it is not necessary to provide a metering communication path 123 outside the main pump 15 as in the hydraulic drive device 110 of the first embodiment. As a result, the structure of the hydraulic drive device 140 can be simplified, thereby achieving a more compact hydraulic drive device 140.

[0171] [Third Implementation]

[0172] Figure 7 This is a schematic diagram of a hydraulic drive device 150 according to the third embodiment (an example of the fluid pressure drive device of the claims). Figure 8 This is an enlarged cross-sectional view of the main part of the hydraulic drive unit 150.

[0173] Figure 9 This is a schematic diagram showing the end face 22A of the end 22a of the cylinder block 22. Figure 10This is a schematic diagram showing the end face (first end face) 43A of the valve plate 43 on the side near the cylinder body 22.

[0174] like Figures 7-10 As shown, the hydraulic drive unit 150 has a single pressure gauge 11 connected to the cylinder chamber 68 of the cylinder body 22 via a pressure metering path 152. A throttle orifice 153 is provided in the pressure metering path 152. Figure 7 For ease of understanding of the structure, the throttle orifice 153 is shown outside the main pump 15. The throttle orifice 153 may not be provided in the pressure metering path 152.

[0175] Specifically, the outer peripheral connecting hole 69a of the end 22a of the cylinder block 22 extends radially inward to form an outer peripheral connecting hole 69a1. Additionally, the inner peripheral connecting hole 69b of the end 22a extends radially outward to form an inner peripheral connecting hole 69b1. The outer peripheral connecting hole 69a1 and the inner peripheral connecting hole 69b1 are formed to overlap each other in the circumferential direction.

[0176] In the third embodiment, an example is described where one peripheral connecting hole selected from a plurality of peripheral connecting holes 69a is formed as a peripheral connecting hole 69a1, and one inner peripheral connecting hole selected from a plurality of inner peripheral connecting holes 69b is formed as an inner peripheral connecting hole 69b1, but this is not a limitation. As another example, for instance, the plurality of peripheral connecting holes 69a may be formed as a peripheral connecting hole 69a1, and the plurality of inner peripheral connecting holes 69b may be formed as an inner peripheral connecting hole 69b1.

[0177] Additionally, a valve plate connecting hole 151 extends through the valve plate 43 in the axial direction. The valve plate connecting hole 151 is formed radially between the outer peripheral discharge port 43b and the inner peripheral discharge port 43c. The valve plate connecting hole 151 is formed to overlap with the outer peripheral connecting hole 69a1 and the inner peripheral connecting hole 69b1 in the circumferential direction.

[0178] The first and second working oils, branched from valve plate 43, are regularly guided from the outer peripheral connecting hole 69a1 and the inner peripheral connecting hole 69b1 to the valve plate connecting hole 151. Consequently, regularly varying ejection pressures P1 and P2 are generated in the valve plate connecting hole 151. A single pressure gauge 11 is connected to this valve plate connecting hole 151 via a pressure metering path 152. Thus, the pressure gauge 11 can alternately (separately) and regularly measure the ejection pressure P1 of the first working oil and the ejection pressure P2 of the second working oil.

[0179] As explained above, according to the hydraulic drive device 150 of the third embodiment, the injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, which are branched into multiple parts by the valve plate 43, can be measured using a single pressure gauge 11. Therefore, similar to the hydraulic drive device 110 of the first embodiment, the control unit 12 can calculate the average pressure based on the measured injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, and the control unit 12 can calculate the pump absorption torque based on the average pressure. As a result, the control unit 12 can determine the maximum pump absorption horsepower (i.e., the swashplate angle of the swashplate 23) based on the calculated pump absorption torque and, for example, the external environment and the rotational speed of the engine 1.

[0180] Therefore, based on the maximum pump absorption horsepower determined by the control unit 12, the swashplate control actuator 14 can be operated using, for example, an electromagnetic proportional valve 13, to control the swashplate 23 to the swashplate angle determined by the control unit 12, thereby controlling the ejection flow rate. Thus, by providing an electromagnetic proportional valve 13 in the torque control unit 6, the swashplate angle of the swashplate 23 can be electronically controlled, enabling precise control of the maximum pump absorption horsepower of the split-type main pump 15.

[0181] Furthermore, a single pressure gauge 11 can be used to measure the injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, which are branched into multiple parts by the valve plate 43. As a result, it is not necessary to have multiple pressure gauges, and similarly to the hydraulic drive device 110 of the first embodiment, the cost of the hydraulic drive device 150 can be reduced.

[0182] Furthermore, the outer peripheral connecting hole 69a1, the inner peripheral connecting hole 69b1, and the pressure metering path 152 are formed inside the main pump 15. As a result, compared to the structure of the hydraulic drive device 110 in the first embodiment, the structure of the hydraulic drive device 150 can be simplified, thereby achieving a more compact hydraulic drive device 150.

[0183] [Fourth Implementation]

[0184] Figure 11 This is a schematic diagram of a hydraulic drive device 160 according to the fourth embodiment (an example of the fluid pressure drive device of the claims). Figure 12 It is a three-dimensional diagram formed by dissecting the front flange 26 and the inclined plate 23. Figure 13 This is a side view of the front flange 26 and the inclined plate 23.

[0185] like Figures 11-13As shown, in the hydraulic drive unit 160, a single pressure gauge 11 is connected to a recess 73 inside the piston 71 via a first pressure metering path 161 and a second pressure metering path 163. A first throttling orifice 164 is provided in the first pressure metering path 161. Additionally, a second throttling orifice 165 is provided in the second pressure metering path 163. Figure 12 In order to facilitate understanding of the structure, the second flow orifice 165 is shown on the outside of the main pump 15 for convenience.

[0186] A throttling orifice may be provided in either the first pressure metering path 161 or the second pressure metering path 163. Alternatively, no throttling orifice may be provided in either the first pressure metering path 161 or the second pressure metering path 163.

[0187] Specifically, a recess 73 is formed inside the piston 71 to accumulate working oil in the cylinder chamber 68. Furthermore, a protrusion 72 of the piston 71 has a protrusion communication hole 72a that communicates with the recess 73. Also, a slipper 77 has a slipper communication hole 77b that communicates with the protrusion communication hole 72a. The slipper communication hole 77b opens into the sliding surface 23a of the inclined plate 23.

[0188] As the cylinder 22 and shaft 21 rotate together around the central axis C, the piston 71 is regularly pulled out of the cylinder chamber 68 and enters the cylinder chamber 68.

[0189] As piston 71 enters cylinder chamber 68, the working oil in cylinder chamber 68 branches into first working oil at outer peripheral discharge port 43b (i.e., valve plate 43) via outer peripheral connecting hole 69a, and is discharged via third connecting path 44a and first discharge path 33a. Additionally, the working oil in cylinder chamber 68 also branches through inner peripheral connecting hole 69b (see...) Figure 4 The oil branched into a second working oil at the inner peripheral side outlet 43c (i.e., valve plate 43), and was discharged via the fourth connecting path 44b and the second discharge path 33b.

[0190] The injection pressure of the first working oil (an example of the high-pressure side piston pressure of the claim) P1 and the injection pressure of the second working oil (an example of the high-pressure side piston pressure of the claim) P2 are regularly transmitted from the recess 73 in the piston 71 to the slipper connecting hole 77b via the protrusion connecting hole 72a.

[0191] A first pressure metering path 161 and a metering recess 162 are provided on the inclined plate 23. The metering recess 162 is formed recessed towards the sliding surface 23a on the curved surface 23b of the inclined plate 23. The curved surface 23b is formed in a curved shape so as to slide along the inner surface 26a of the front flange 26. Thus, the inclined plate 23 is provided in a manner that allows it to tilt relative to the inner surface 26a of the front flange 26. The metering recess 162 communicates with the slipper communication hole 77b via the first pressure metering path 161. In addition, the metering recess 162 opens relatively large towards the inner surface 26a of the front flange 26, for example, in a rectangular shape.

[0192] A second pressure metering path 163 is formed on the front flange 26. One end of the second pressure metering path 163 communicates with the opening of the metering recess 162. The opening of the metering recess 162 is formed to be larger along the curved surface 23b. Therefore, within the range of the inclination of the inclined plate 23 relative to the inner surface 26a of the front flange 26, the communication between one end of the second pressure metering path 163 and the opening of the metering recess 162 is ensured. The other end of the second pressure metering path 163 is connected to a single pressure gauge 11.

[0193] That is, the pressure gauge 11 is connected to the recess 73 in the piston 71 via the second pressure measurement path 163, the measurement recess 162, the first pressure measurement path 161, the slipper connecting hole 77b, and the protrusion connecting hole 72a. Thus, the pressure gauge 11 can alternately (respectively) and regularly measure the injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil in the recess 73.

[0194] As explained above, according to the hydraulic drive device 160 of the fourth embodiment, the injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, which are branched into multiple parts by the valve plate 43, can be measured using a single pressure gauge 11. Therefore, similar to the hydraulic drive device 110 of the first embodiment, the control unit 12 can calculate the average pressure based on the measured injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, and the control unit 12 can calculate the pump absorption torque based on the average pressure. Thus, the control unit 12 can determine the maximum pump absorption horsepower (i.e., the swashplate angle of the swashplate 23) based on the calculated pump absorption torque and, for example, the external environment and the rotational speed of the engine 1.

[0195] As a result, the pump flow rate can be controlled by operating the swashplate control actuator 14 using, for example, an electromagnetic proportional valve 13, based on the maximum pump absorption horsepower determined by the control unit 12, thereby controlling the swashplate 23 to the swashplate angle determined by the control unit 12. Thus, by providing an electromagnetic proportional valve 13 in the torque control unit 6, the swashplate angle of the swashplate 23 can be electronically controlled, and the pump absorption horsepower of the split-type main pump 15 can be controlled with high precision.

[0196] Furthermore, a single pressure gauge 11 can be used to measure the injection pressure P1 of the first working oil and the injection pressure P2 of the second working oil, which are branched into multiple parts by the valve plate 43. As a result, it is not necessary to have multiple pressure gauges, and similarly to the hydraulic drive device 110 of the first embodiment, the cost of the hydraulic drive device 160 can be reduced.

[0197] Furthermore, the first pressure metering path 161, the metering recess 162, and the second pressure metering path 163 are formed inside the main pump 15. As a result, compared to the structure of the hydraulic drive device 110 in the first embodiment, the structure of the hydraulic drive device 160 can be simplified, thereby achieving a more compact hydraulic drive device 160.

[0198] This invention is not limited to the embodiments described above, but includes various modifications to the embodiments described above without departing from the spirit of this invention.

[0199] For example, in the above embodiment, the case where the construction machinery 100 is a hydraulic excavator has been described. However, it is not limited to this, and the above-described hydraulic drive devices 110, 140, 150, and 160 can be used in a wide variety of construction machinery.

[0200] Furthermore, in the embodiments described above, hydraulic drive devices 110, 140, 150, and 160 are exemplified as fluid pressure drive devices, but the embodiments are not limited to this. The above-described structure can be adopted in a wide variety of fluid pressure drive devices that utilize fluid pressure for propulsion.

[0201] Furthermore, in the above embodiment, the electromagnetic proportional valve 13 is exemplified as a solenoid valve, but the solenoid valve is not limited to an electromagnetic proportional valve. Various types of solenoid valves can be used.

[0202] Furthermore, in the above embodiment, an example was described in which the maximum absorbable horsepower of the pump is determined based on the pressure value measured by the pressure gauge 11 (i.e., the swashplate angle of the swashplate 23), and the swashplate angle of the swashplate 23 is controlled by the electromagnetic proportional valve 13, but this is not a limitation. As another example, the electromagnetic proportional valve 13 can also be used to control the engine.

[0203] Furthermore, in the above embodiment, a control cylinder is exemplified as the swashplate control actuator 14, but it is not limited to this. Any actuator that controls the swashplate angle of the swashplate 23 using an electrical signal from the control unit 12 is acceptable.

[0204] Industrial availability

[0205] According to the aforementioned fluid pressure drive device, the pump absorption horsepower of, for example, a split-type pump can be controlled with high precision, thereby reducing costs.

Claims

1. A fluid pressure driven device, comprising: A fluid pressure pump that uses a swashplate to control the flow rate of the ejected fluid into multiple ejection paths; A single pressure sensing unit alternately detects any one of the pressures of the ejected fluids sprayed into the plurality of ejection flow paths; and The control unit controls the ejection flow rate based on the pressure value detected by the pressure detection unit. The fluid pump includes: A cylinder, which has multiple cylinder chambers; A piston, which is movably disposed within the cylinder chamber, performs the intake of fluid into the cylinder chamber and the ejection of fluid from the cylinder chamber; as well as A valve plate that branches the ejected fluid from the cylinder into the plurality of ejection paths. The cylinder has a plurality of cylinder communication holes that connect each of the cylinder chambers to one of the plurality of ejection flow paths. The valve plate has: Multiple discharge ports, each connected to one of the multiple ejection flow paths corresponding to the multiple cylinder communication holes; and The valve plate communication hole communicates independently with the cylinder communication hole relative to each of the aforementioned discharge ports. The pressure detection unit detects the pressure in the valve plate communication hole.

2. The fluid pressure drive device according to claim 1, wherein, The control unit controls the inclined plate based on an average pressure, which is calculated from the pressure detected alternately by the pressure detection unit.

3. The fluid pressure drive device according to claim 1 or 2, wherein, The control unit determines the pump's maximum absorption horsepower based on the pressure value detected by the pressure detection unit. The fluid pressure drive device is equipped with a solenoid valve that is controlled based on the maximum absorption horsepower of the pump.

4. The fluid pressure drive device according to claim 3, wherein, The control unit determines the angle of the swashplate based on the maximum absorption horsepower of the pump. The solenoid valve controls the inclined plate based on the inclined plate angle.

5. A fluid pressure driven device, comprising: A fluid pressure pump that uses a swashplate to control the flow rate of the ejected fluid into multiple ejection paths; A single pressure sensing unit alternately detects any one of the pressures of the ejected fluids sprayed into the plurality of ejection flow paths; and The control unit controls the ejection flow rate based on the pressure value detected by the pressure detection unit. The pressure of each of the ejected fluids ejected into the plurality of ejection flow paths is the high-pressure side piston pressure obtained from the inclined plate side. The fluid pump includes: A cylinder, which has a cylinder chamber; and A piston, which is freely movable within the cylinder chamber, performs the intake of fluid into the cylinder chamber and the ejection of fluid from the cylinder chamber. A metering path communicating with the cylinder chamber is formed by the piston and the inclined plate. The high-pressure side piston pressure is obtained from the inclined plate via the piston.

6. The fluid pressure drive device according to claim 5, wherein, The control unit controls the inclined plate based on an average pressure, which is calculated from the pressure detected alternately by the pressure detection unit.

7. The fluid pressure drive device according to claim 5 or 6, wherein, The control unit determines the pump's maximum absorption horsepower based on the pressure value detected by the pressure detection unit. The fluid pressure drive device is equipped with a solenoid valve that is controlled based on the maximum absorption horsepower of the pump.

8. The fluid pressure drive device according to claim 7, wherein, The control unit determines the angle of the swashplate based on the maximum absorption horsepower of the pump. The solenoid valve controls the inclined plate based on the inclined plate angle.

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