Hydraulic control device

Abstract

A hydraulic control device that can reduce electrical energy consumption and noise while suppressing an increase in the number of parts is provided. [Solution] A hydraulic control device 10 having a variable displacement oil pump 11 driven by an electric motor 32, comprising oil passages 31, 79 through which oil is discharged from the variable displacement oil pump 11, a manual valve 65 for connecting and disconnecting the oil passages 31, 79, a swash plate 22 for changing the oil discharge rate of the variable displacement oil pump 111, a first control cylinder 16 for increasing the oil discharge rate of the variable displacement pump 11, a second control cylinder 17 for decreasing the oil discharge rate of the variable displacement pump 11, a control valve 19 for opening and closing the oil passage leading to the second control cylinder 17, and a solenoid valve 83 for supplying oil to the second control cylinder 17, and the solenoid valve 83 can change the amount of oil supplied.

Description

[Technical Field]

[0001] The present disclosure relates to a hydraulic control device capable of controlling the discharge amount of a variable displacement oil pump. [Background technology]

[0002] An example of a hydraulic control device capable of controlling the discharge rate of a variable displacement oil pump is described in Patent Document 1. The centralized hydraulic supply system described in Patent Document 1 is a centralized hydraulic supply system that supplies a constant hydraulic pressure to hydraulic systems that drive hydraulically driven deck machinery, cargo oil pumps, ballast pumps, etc. used on ships or oil tankers.

[0003] The centralized hydraulic supply system described in Patent Document 1 aims to provide a centralized hydraulic supply system that reduces noise, saves energy, is easy to control, is highly reliable, and is inexpensive. The centralized hydraulic supply system described in Patent Document 1 is equipped with one variable displacement pump and multiple fixed displacement pumps, and is also provided with a regulator and a pressure sensor that automatically starts and stops the variable displacement pumps. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 57-127870 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present application recognized that the centralized hydraulic supply system described in Patent Document 1 has a problem in that, in order to save energy and reduce noise, it is provided with one variable displacement pump and multiple fixed displacement pumps, which increases the number of parts.

[0006] An object of the present disclosure is to provide a hydraulic control device that can save electrical energy and reduce noise while suppressing an increase in the number of parts. [Means for solving the problem]

[0007] This embodiment relates to a hydraulic control device having a variable displacement oil pump driven by the rotational force of an electric motor and discharging oil to be supplied to an oil-requiring device, the hydraulic control device including: a first oil passage through which oil is discharged from the variable displacement oil pump; a second oil passage connected to the first oil passage and supplying the oil discharged to the first oil passage to the oil-requiring device; a switching valve connecting and disconnecting the first oil passage and the second oil passage; an operating member provided in the variable displacement oil pump and operable to change the oil discharge amount; a first operating force applying mechanism operated by the hydraulic pressure of the oil discharged from the variable displacement oil pump and applying an operating force to the operating member in a direction to increase the oil discharge amount of the variable displacement pump; and a second operating force applying mechanism operated by the hydraulic pressure of a first hydraulic chamber and applying an operating force to the operating member in a direction to decrease the oil discharge amount of the variable displacement pump. a second operating force imparting mechanism that imparts oil to the first hydraulic chamber; a third oil passage that sends a portion of the oil in the first oil passage to the first hydraulic chamber; and a control valve that opens and closes the third oil passage, wherein the control valve is configured to be switchable between a first state in which the first oil passage and the second oil passage are connected by the switching valve and the third oil passage is closed when the oil pressure in the first oil passage is below a predetermined oil pressure, and a second state in which the first oil passage and the second oil passage are blocked by the opening / closing valve and the third oil passage is opened when the oil pressure in the first oil passage is equal to or higher than the predetermined oil pressure; and wherein the control valve is configured to be switchable between a first ... connected by the switching valve and the third oil passage is opened when the oil pressure in the first oil passage is equal to or higher than the predetermined oil pressure; and wherein the control valve is configured to be switchable between a first state in which the first oil passage and the second oil passage are connected by the switching valve and the third oil passage is opened when the oil pressure in the first oil passage is equal to or higher than the predetermined oil pressure; and wherein the control valve is configured to be switchable between a first state in which the first oil passage and the second oil passage are blocked by the opening / closing valve and the third oil passage is opened; and wherein the control valve is configured to be switchable between a first state in which the first oil passage and the second oil passage are connected by the switching valve and the third oil passage is opened when the oil pressure in the first oil passage is equal to or higher than the predetermined oil pressure; and wherein the control valve is configured to be switchable between a first state in which the first oil passage and the second oil passage are connected by the switching valve and the third oil passage is [Effects of the Invention]

[0008] According to this embodiment, it is possible to provide a hydraulic control device that can reduce electrical energy consumption and noise while suppressing an increase in the number of parts. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram showing the configuration of a hydraulic control device. [Figure 2] FIG. 2 is an enlarged view of a first circuit section included in the hydraulic control device. [Figure 3] 3 is an enlarged view showing a first example of a third circuit section included in the hydraulic control device. FIG. [Figure 4] FIG. 4 is a graph showing an example of a change over time in the value of a current supplied to an electric motor. [Figure 5] FIG. 10 is an enlarged view showing a specific example 2 of the third circuit section. DETAILED DESCRIPTION OF THE INVENTION

[0010] (overview) Hereinafter, an embodiment of the hydraulic control device will be described with reference to the drawings. In the drawings for explaining the embodiment of the hydraulic control device, the same parts are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0011] The hydraulic control device 10 shown in FIG. 1 is configured to supply oil discharged from a variable displacement oil pump 11 to an oil-requiring device 12. The hydraulic control device 10 has a first circuit section 13, a second circuit section 14, a third circuit section 15, and an electric motor 32. The first circuit section 13 controls the flow rate of oil discharged from the variable displacement oil pump 11, i.e., the oil discharge amount. The second circuit section 14 is configured to supply oil discharged from the first circuit section 13 to the oil-requiring device 12. The third circuit section 15 controls the first circuit section 13. The oil-requiring device 12 may be any of a hydraulically driven marine device, such as a windlass, a winch, a jack-up device, etc. The oil-requiring device 12 has a hydraulically operated operating element, such as a rotating element, a reciprocating element, etc.

[0012] (Explanation of the first circuit section) 2, the first circuit section 13 has a variable displacement oil pump 11, a first control cylinder 16, a second control cylinder 17, a relief valve 18, a first control valve 19, and a second control valve 20. The variable displacement oil pump 11 is, for example, an axial piston pump, and has an input shaft 21, a swash plate 22, pistons, a cylinder block, an intake port 23, a discharge port 24, an exhaust port 25, etc. The input shaft 21 is connected to the electric motor 32 shown in FIG. 1 so as to be able to transmit power, and a cylinder is attached to the input shaft 21.

[0013] The electric motor 32 is a power source that rotates when supplied with electric power (electrical energy). The electric motor 32 can control a predetermined rotation speed per minute, for example, within a range of 1200 [min-1] to 1800 [min-1]. The predetermined rotation speed per minute of the electric motor 32 is fixed to a constant rotation speed according to the amount of oil required by the oil-requiring device 12, i.e., the target oil pressure. Furthermore, multiple pistons are movably provided within the cylinder. The intake port 23 is connected to an oil tank 27 via an oil passage 26. Oil is stored in the oil tank 27.

[0014] The discharge port 25 is connected to the oil tank 27 via oil passages 28 and 29. The discharge port 24 is connected to an oil passage 31. When the input shaft 21 is rotated by the rotational force of the electric motor 32, the cylinder rotates and the piston moves back and forth, causing the variable displacement oil pump 11 to suck oil from the oil tank 27 through the suction port 23 and discharge the sucked oil from the discharge port 24 to the oil passage 31. The variable displacement oil pump 11 discharges excess oil that has been sucked in and not discharged to the discharge port 24 from the discharge port 25 to the oil passage 28.

[0015] The swash plate 22 is configured so that its inclination angle can be changed. Assuming that the rotational speed of the input shaft 21 is constant, the greater the inclination angle of the swash plate 22, the longer the stroke of the pistons' reciprocating movement. This increases the displacement of the variable displacement oil pump 11, i.e., the amount of oil discharged from the discharge port 24. When the inclination angle of the swash plate 22 is at its minimum angle, e.g., zero degrees, the pistons do not move even when the input shaft 21 rotates, and no oil is discharged from the discharge port 24. The maximum discharge amount of the variable displacement oil pump 11, i.e., the maximum discharge pressure, depends on the maximum inclination angle of the swash plate 22.

[0016] The first control cylinder 16 and the second control cylinder 17 are provided to change the inclination angle of the swash plate 22. The first control cylinder 16 has a reciprocating piston 33, a hydraulic chamber 34 that generates pressure to bias the piston 33, and a spring 35 provided in the hydraulic chamber 34. The hydraulic chamber 34 is connected to the hydraulic passage 31 by an oil passage 36. Therefore, the hydraulic pressure in the oil passage 31 is transmitted to the hydraulic chamber 34. The piston 33 is operated by the biasing force of the spring 35 and a biasing force corresponding to the pressure in the hydraulic chamber 34.

[0017] The second control cylinder 17 has a reciprocating piston 37 and a hydraulic chamber 38 that generates pressure to urge the piston 37. The area of ​​the piston 37 that receives the hydraulic pressure from the hydraulic chamber 38 exceeds the area of ​​the piston 33 that receives the hydraulic pressure from the hydraulic chamber 34. The hydraulic chamber 38 is connected to oil passages 39 and 40. The oil passage 40 is connected to the third circuit portion 15. The operating forces of the pistons 33 and 37 are both transmitted to the swash plate 22. When the hydraulic pressure in the hydraulic chamber 38 increases and the piston 37 operates, the inclination angle of the swash plate 22 decreases.

[0018] When the operating force applied to the swash plate 22 from the piston 33 of the first control cylinder 16 exceeds the operating force applied to the swash plate 22 from the piston 37 of the second control cylinder 17, the inclination angle of the swash plate 22 increases. In other words, the amount of oil discharged from the variable displacement oil pump 11 increases. When the operating force applied to the swash plate 22 from the piston 33 of the first control cylinder 16 is less than the operating force applied to the swash plate 22 from the piston 37 of the second control cylinder 17, the inclination angle of the swash plate 22 decreases. In the variable displacement oil pump 11, the amount of oil discharged decreases as the inclination angle of the swash plate 22 decreases.

[0019] The first control valve 19 has a spool, a spring 101 that biases the spool, ports 42, 43, 44, 53, and 54, and a feedback port 41. The feedback port 41 and port 42 are connected to an oil passage 45. The oil passage 45 is connected to an oil passage 31. The ports 43 and 54 are connected to an oil passage 29 via an oil passage 55. The port 53 is connected to an oil passage 52. A biasing force corresponding to the oil pressure at the feedback port 41 and a biasing force of the spring 101 are applied to the spool of the first control valve 19 in opposite directions.

[0020] When the spool is operated, the first control valve 19 switches between a first state and a second state. The first control valve 19 is in the first state when the oil pressure in the oil passage 31, specifically the oil pressure at the feedback port 41, is lower than a first predetermined oil pressure. When the first control valve 19 is in the first state, the ports 53 and 54 are connected, the ports 53 and 42 are blocked, and the ports 43 and 44 are connected.

[0021] The first control valve 19 is in the second state when the hydraulic pressure at the feedback port 41 is equal to or higher than a first predetermined hydraulic pressure. When the first control valve 19 is in the second state, the ports 53 and 42 are connected, the ports 53 and 54 are blocked, and the ports 43 and 44 are blocked.

[0022] The second control valve 20 has a spool, a spring 102 that biases the spool, ports 47, 48, 49, and 50, and a feedback port 46. The feedback port 46 is connected to an oil passage 45. The port 47 is also connected to the oil passage 45 via an oil passage 51. The ports 48 and 49 are connected to an oil passage 52. The port 50 is connected to an oil passage 39. The biasing force corresponding to the oil pressure at the feedback port 46 and the biasing force of the spring 102 are applied to the spool of the second control valve 20 in opposite directions.

[0023] The second control valve 20 switches between a first state and a second state when the spool is operated. The second control valve 20 is in the first state when the oil pressure in the oil passage 31, specifically, the oil pressure at the feedback port 46, is less than a first predetermined oil pressure. When the second control valve 20 is in the first state, the port 50 and the port 48 are connected, and the port 50 and the port 47 are blocked. When the oil pressure at the feedback port 46 is equal to or greater than the first predetermined oil pressure, the second control valve 20 is in the second state. When the second control valve 20 is in the second state, the port 50 and the port 47 are connected, and the port 50 and the port 48 are blocked.

[0024] When the first control valve 19 and the second control valve 20 are both in the first state, the hydraulic chamber 38 is connected to the hydraulic line 29 via the hydraulic lines 39, 52, and 55. When at least one of the first control valve 19 or the second control valve 20 is in the second state, the hydraulic chamber 38 is blocked from the hydraulic line 29. The first predetermined hydraulic pressure is determined according to the spring constant of the spring 101 of the first control valve 19 and the spring constant of the spring 102 of the second control valve 20. The spring constant of the spring 101 and the spring constant of the spring 102 are set to be the same.

[0025] The relief valve 18 has a spool, a spring 56 that biases the spool, ports 57 and 58, and a feedback port 59. The port 57 is connected to the oil passage 29 via an oil passage 60. The port 58 is connected to the port 44 via an oil passage 61. The port 58 is also connected to the feedback port 59 via an oil passage 62. The spring 56 is interposed between the spool and the piston 37 of the second control cylinder 17.

[0026] (Explanation of the second circuit section) The second circuit portion 14 has a relief valve 63, a check valve 64, a manual valve 65, etc. The relief valve 63 is provided to suppress an increase in oil pressure in the oil passage 31. The relief valve 63 has a spool, a spring 66, ports 67 and 68, and a feedback port 69. The port 67 is connected to the oil passage 31. The port 67 is connected to the feedback port 69 via an oil passage 70. The port 68 is connected to the oil tank 27 via an oil passage 71.

[0027] The inlet of check valve 64 is connected to oil passage 31, and the outlet of check valve 64 is connected to oil passage 72. Check valve 64 is opened in the direction in which oil is supplied from oil passage 31 to oil passage 72, and is closed in the direction in which oil flows back from oil passage 72 to oil passage 31. Check valve 64 is opened when the oil pressure in oil passage 72 is lower than the oil pressure in oil passage 31. Check valve 64 is closed when the oil pressure in oil passage 72 is equal to or higher than the oil pressure in oil passage 31.

[0028] The manual valve 65 is provided to switch the oil supply state to the oil-requiring device 12. The manual valve 65 has a reciprocating spool, a plunger 65A connected to the spool, an inlet port 74, supply ports 75 and 76, and a discharge port 77. An operating lever 73 is attached to the plunger 65A. When the operating lever 73 is manually operated by an operator, the spool moves, switching the oil supply state to the oil-requiring device 12. The operating lever 73 has three operating positions, for example, a first operating position, a neutral position, and a second operating position. A proximity switch 100 is also provided to detect whether the operating lever 73 is in the neutral position. The proximity switch 100 is a non-contact sensor that outputs a signal corresponding to, for example, the strength of a high-frequency magnetic field.

[0029] The inlet port 74 is connected to the oil passage 72. The discharge port 77 is connected to the oil passage 78. The supply port 75 is connected to the oil-requiring device 12 via an oil passage 79. The supply port 76 is connected to the oil-requiring device 12 via an oil passage 80. The oil passages 79 and 80 are arranged in parallel between the manual valve 65 and the oil-requiring device 12. In addition, a pressure gauge 81 is provided to detect and display the oil pressure in the oil passage 31. The operator can visually check the pressure gauge 81.

[0030] When the operating lever 73 is in the first operating position, the manual valve 65 is held in a first operating state. When the manual valve 65 is held in the first operating state, the inlet port 74 is connected to the supply port 75, and the discharge port 77 is connected to the supply port 76. Furthermore, when the manual valve 65 is held in the first operating state, the amount of oil supplied from the inlet port 74 to the supply port 75 is continuously adjustable.

[0031] When the operating lever 73 is in the second operating position, the manual valve 65 is held in a second operating state. When the manual valve 65 is held in the second operating state, the inlet port 74 is connected to the supply port 76, and the discharge port 77 is connected to the supply port 75. When the manual valve 65 is held in the second operating state, the amount of oil supplied from the inlet port 74 to the supply port 76 is continuously adjustable.

[0032] When the operating lever 73 is in the neutral position, the manual valve 65 is held in the neutral state. When the manual valve 65 is held in the neutral state, the inlet port 74 and the discharge port 77 are connected, and the supply port 75 and the supply port 76 are blocked. Therefore, the oil in the oil passage 72 is discharged to the oil passage 78 via the inlet port 74 and the discharge port 77. Furthermore, oil is not supplied to the oil-requiring device 12.

[0033] (Example 1 of the third circuit section) 3 shows a first specific example of the third circuit portion 15. The third circuit portion 15 may have a pressure reducing valve 82 and a solenoid valve 83. The pressure reducing valve 82 has a spool, a spring, an input port 84, an output port 85, a discharge port 86, and a feedback port 87. The input port 84 is connected to an oil passage 88, and the oil passage 88 is connected to a discharge port 90 of a variable displacement oil pump 89.

[0034] An intake port 91 of the variable displacement oil pump 89 is connected to the oil tank 27. The variable displacement oil pump 89 is driven by an electric motor 92 to draw oil from the oil tank 27 and discharge the drawn oil into an oil passage 88. The rotation speed of the electric motor 92 is controlled to be constant.

[0035] An output port 85 of the pressure reducing valve 82 is connected to an oil passage 93. The oil passage 93 is connected to a feedback port 87 via an oil passage 94. The discharge port 86 is connected to the oil tank 27 via an oil passage 97.

[0036] The pressure reducing valve 82 has a function of preventing the pressure of the oil supplied from the oil passage 88 to the oil passage 93 from exceeding a predetermined value. For example, when the pressure in the oil passage 93 is below the predetermined value, the input port 84 and the output port 85 are connected, and the discharge port 86 is closed. Therefore, the oil in the oil passage 88 is supplied to the oil passage 93.

[0037] When the pressure in oil passage 93 is equal to or higher than a predetermined value, the input port 84 and the output port 85 are blocked, the input port 84 and the discharge port 86 are connected, and the output port 85 is closed. Therefore, the oil in oil passage 88 is returned to the oil tank 27 via oil passage 97, and the oil pressure in oil passage 93 is prevented from exceeding a predetermined value.

[0038] The solenoid valve 83 has a spool, an electromagnetic coil, an input port 95, an output port 96, and a spring 98. The output port 96 is connected to the oil passage 40. In other words, the first control valve 19, the second control valve 20, and the solenoid valve 83 are connected in parallel to each other across the hydraulic chamber 38. The input port 95 is connected to the oil passage 93. The solenoid valve 83 can switch between supplying power to the electromagnetic coil (ON) and cutting off power to the electromagnetic coil (OFF). When the solenoid valve 83 is OFF, the spool is stopped in the standby position by the biasing force of the spring 98. Therefore, the input port 95 and the output port 96 are cut off, and oil in the oil passage 93 is not supplied to the oil passage 40.

[0039] When the solenoid valve 83 is turned on, a magnetic attractive force is generated, causing the spool to move against the biasing force of the spring 98, connecting the input port 95 and the output port 96. Therefore, oil in the oil passage 93 is supplied to the oil passage 40.

[0040] The solenoid valve 83 can be continuously switched on and off. The solenoid valve 83 can also linearly control the ratio of on time to off time within a predetermined period of time, i.e., the duty ratio. A controller 99 is provided to control the duty ratio of the solenoid valve 83. The controller 99 may be implemented by a computer having an input device 99A, a processor 99B, a main memory device 99C, an auxiliary memory device 99D, a communication device 99E, etc. The input device 99A is a device operated by an operator, and may be implemented by an operation panel, operation buttons, operation switches, etc.

[0041] The processor 99B may be configured, for example, by a central processing unit (CPU) in which an arithmetic unit (arithmetic circuit) and a control unit (control circuit) are integrated. The processor 99B is communicatively connected to the input device 99A, main memory device 99C, auxiliary memory device 99D, communication device 99E, etc. via a communication bus. The main memory device 99C may be realized, for example, by RAM (Random Access Memory). The main memory device 99C functions as a work area and buffer area for storing programs, data, instructions, etc. when the processor 99B processes and executes the programs, data, instructions, etc. retrieved from the auxiliary memory device 99D. The main memory device 99C is a non-transitory storage medium.

[0042] The auxiliary storage device 99D is a non-transitory storage medium that stores non-transitory programs, information, and data operated by the processor 99B. The communication device 99E may be configured, for example, by a communication circuit, a communication cable, a communication antenna, a communication port, etc. The communication device 99E is connected to a current circuit 130 that controls the supply of electricity to the solenoid valves 83, 120. When the program is executed, the processor 99D may determine whether the operating lever 73 is stopped in the neutral position by processing a signal output from the proximity switch 100. The processor 99D may output a control signal to control the current circuit 130 based on the result of determining whether the operating lever 73 is stopped in the neutral position.

[0043] An operator can operate the input device 99A. Operation information input by operating the input device 99A is input to the processor 99B, and the processor 99B can control the duty ratio of the solenoid valve 83. Data and information for controlling the duty ratio of the solenoid valve 83 are stored in the auxiliary storage device 99D.

[0044] The controller 99 may process the signal from the proximity switch 100 and control the duty ratio of the solenoid valve 83 based on data and information stored in memory. The controller 99 may optionally control the duty ratio of the solenoid valve 83 within a range of 0% to 100% by PWM (Pulse Width Modulation) control of a switch circuit connected to the electromagnetic coil of the solenoid valve 83. Assuming that the oil discharge amount of the variable displacement oil pump 89 is constant, as the duty ratio of the solenoid valve 83 increases, the amount of oil supplied from the oil passage 93 to the oil passage 40 increases.

[0045] For example, when the controller 99 controls the duty ratio of the solenoid valve 83 to 100%, the amount of oil supplied from the oil passage 93 to the oil passage 40 is maximized. When the controller 99 controls the duty ratio of the solenoid valve 83 to 0%, the amount of oil supplied from the oil passage 93 to the oil passage 40 is minimized.

[0046] (Example of hydraulic control device functions) (1) Overview An example of the function of the hydraulic control device 10 is as follows. When the electric motor 32 rotates at a predetermined rotational speed, the variable displacement oil pump 11 is driven by the rotational force of the electric motor 32. When the variable displacement oil pump 11 is driven, oil from the oil tank 27 is sucked into the variable displacement oil pump 11 via the oil passage 26, and the oil is discharged from the variable displacement oil pump 11 to the oil passage 31. Of the amount of oil sucked into the variable displacement oil pump 11, the amount of oil in excess of the amount of oil discharged to the oil passage 31 is discharged from the outlet port 25 to the oil passage 28. The oil discharged to the oil passage 28 is returned to the oil tank 27 through the oil passage 29.

[0047] When oil is discharged from variable displacement oil pump 11 to oil passage 31, check valve 64 opens and oil in oil passage 31 is supplied to oil passage 72. When manual valve 65 is held in the first operating state, inlet port 74 is connected to supply port 75, and discharge port 77 is connected to supply port 76. Therefore, the oil supplied to oil passage 72 is supplied to oil-requiring device 12 through oil passage 79. In addition, oil in oil passage 80 is discharged to oil passage 78.

[0048] When the manual valve 65 is held in the second operating state, the inlet port 74 is connected to the supply port 76, and the discharge port 77 is connected to the supply port 75. Therefore, the oil supplied to the oil passage 72 is supplied to the oil-requiring device 12 through the oil passage 80. In addition, the oil in the oil passage 79 is discharged to the oil passage 78.

[0049] When the manual valve 65 is switched between the first operating state and the second operating state, the operating state of the operating member in the oil-requiring device 12, for example, the rotation direction of the rotating element, is reversed. Also, the operating state of the operating member in the oil-requiring device 12, for example, the operating direction of the reciprocating element, is reversed.

[0050] When the manual valve 65 is held in the neutral state, the inlet port 74 and the discharge port 77 are connected, and the supply port 75 and the supply port 76 are closed. Therefore, oil is not supplied from the oil passage 72 to the oil-requiring device 12, and the operating members of the oil-requiring device 12 are stopped.

[0051] (2) Example of manual valve in first or second operating state When the operating lever 73 is stopped at the first operating position or the second operating position, the controller 99 controls the duty ratio of the solenoid valve 83 to 0%. Therefore, the spool of the solenoid valve 83 is pushed to a stop by the biasing force of the spring 98, and the input port 95 and the output port 96 are blocked. Therefore, the oil in the oil passage 93 is not supplied to the hydraulic chamber 38 via the oil passage 40.

[0052] The action and operation of the first circuit section 13 and the second circuit section 14 when the operating lever 73 is stopped in the neutral position and the manual valve 65 is held in the first operating state or the second operating state will be specifically explained. When the amount of oil supplied to the oil-requiring device 12 is less than the amount of oil required by the oil-requiring device 12, the check valve 64 is opened and the oil in the oil passage 31 is supplied to the oil passage 72. As a result, the oil pressure in the oil passage 31 decreases or is held approximately constant.

[0053] On the other hand, if the amount of oil supplied to the oil-requiring device 12 is equal to or greater than the amount of oil required by the oil-requiring device 12, the oil pressure in the oil passage 31 will rise. The amount of oil supplied to the oil-requiring device 12 is the amount of oil per predetermined time. The amount of oil required by the oil-requiring device 12 is the amount of oil per predetermined time.

[0054] When the oil pressure in oil passage 31 is equal to or lower than a second predetermined oil pressure, the spool of relief valve 63 blocks port 67 and port 68. Therefore, the oil in oil passage 31 is not discharged to oil passage 71, and the oil pressure in oil passage 31 increases. When the oil pressure in oil passage 31 exceeds the second predetermined oil pressure, the spool of relief valve 63 is operated by the oil pressure at feedback port 69, and port 67 and port 68 are connected. Therefore, the oil in oil passage 31 is discharged to oil passage 71 through ports 67 and 68 and returned to the oil tank 27.

[0055] Therefore, an increase in the oil pressure in the oil passage 31 is suppressed. The second predetermined oil pressure is higher than the first predetermined oil pressure and is determined depending on the durability and strength of the elements and parts that make up the hydraulic control device 10. The second predetermined oil pressure can be changed by changing the spring constant of the spring 66. As the spring constant of the spring 66 increases, the second predetermined oil pressure increases.

[0056] A portion of the oil in oil passage 31 is sent to hydraulic chamber 34 through oil passage 36 shown in Figure 2. Piston 33 of first control cylinder 16 is biased leftward in Figure 2 by the biasing force of spring 35 and a biasing force corresponding to the pressure in hydraulic chamber 34. A portion of the oil in oil passage 31 is sent to feedback ports 41, 46 via oil passage 45. The hydraulic pressures at feedback ports 41, 46 are the same.

[0057] When the amount of oil supplied to the oil-requiring device 12 is less than the amount of oil required by the oil-requiring device 12, the hydraulic pressure in the oil passage 31 is equal to or less than the second predetermined hydraulic pressure. Therefore, the spool of the first control valve 19 is operated by the biasing force of the spring 101 against the hydraulic pressure of the feedback port 41. Therefore, the ports 53 and 54 are connected, the port 42 is closed, and the ports 43 and 44 are connected. Furthermore, the spool of the second control valve 20 is operated by the biasing force of the spring 102 against the hydraulic pressure of the feedback port 46. Therefore, the ports 48 and 50 are connected, and the port 47 is closed.

[0058] As a result, oil in the hydraulic chamber 38 of the second control cylinder 17 is discharged to the oil passage 29 via the oil passages 39, 52, and 55. In other words, the hydraulic pressure in the hydraulic chamber 38 drops. Therefore, the piston 37 is urged rightward in FIG. 2 by the urging force of the first control cylinder 16 and the urging force of the spring 56 acting on the swash plate 22. In this way, the inclination angle of the swash plate 22 is increased and maintained at a predetermined angle. In other words, the discharge rate of the variable displacement oil pump 11 increases and is maintained at a predetermined rate.

[0059] Meanwhile, a portion of the oil passing through oil passage 29 is sent to relief valve 18 via oil passage 55, ports 43 and 44, and oil passage 61. Here, when the oil pressure at feedback port 59 is equal to or lower than a predetermined pressure, relief valve 18 blocks port 58 from port 57. Therefore, the oil in oil passage 61 is not discharged to oil passage 60. When the oil pressure at feedback port 59 exceeds the predetermined pressure, relief valve 18 connects port 58 to port 57. Therefore, the oil in oil passage 61 is discharged to oil passage 60. In addition, spring 56 is compressed, and the biasing force to the right in FIG. 2 that is applied from spring 56 to piston 37 increases.

[0060] Furthermore, the pressure in hydraulic chamber 34 is higher than the pressure in hydraulic chamber 38, and a biasing force corresponding to the biasing forces of springs 35 and 56 is applied to piston 37. As a result, piston 37 is moved rightward in FIG. 2, and the discharge rate of variable displacement oil pump 11 increases and is maintained at a predetermined rate.

[0061] If the amount of oil supplied to the oil-requiring device 12 is equal to or greater than the amount of oil required by the oil-requiring device 12, the hydraulic pressure in the oil passage 31 exceeds a predetermined pressure. As a result, the spool of the first control valve 19 is operated by the hydraulic pressure of the feedback port 41 against the biasing force of the spring 101. Therefore, the ports 53 and 42 are connected, the port 54 is closed, and the ports 43 and 44 are blocked. In addition, the spool of the second control valve 20 is operated by the hydraulic pressure of the feedback port 46 against the biasing force of the spring 102. Therefore, the ports 47 and 50 are connected, and the port 48 is closed.

[0062] As a result, oil in the oil passage 45 is supplied to the hydraulic chamber 38 via the oil passages 52 and 39, and the hydraulic pressure in the hydraulic chamber 38 increases. Here, the biasing force applied to the piston 37 in accordance with the hydraulic pressure in the hydraulic chamber 38 exceeds the biasing force of the first control cylinder 16 and the biasing force of the spring 56 applied to the swash plate 22. Therefore, the piston 37 is biased to the right in FIG. 2, and the inclination angle of the swash plate 22 is reduced and maintained at a predetermined angle. In other words, the discharge rate of the variable displacement oil pump 11 is reduced and maintained at a predetermined rate.

[0063] As described above, the operating states of the first control valve 19 and the second control valve 20 are switched in response to changes in the oil pressure in the oil passage 31, and the oil pressure in the oil pressure chamber 38 changes. As a result, the inclination angle of the swash plate 22 increases or decreases, and the discharge rate of the variable displacement oil pump 11 automatically changes, i.e., increases or decreases.

[0064] Furthermore, whether the manual valve 65 is in the first operating state or the second operating state, if the amount of oil supplied to the oil-requiring device 12 exceeds the amount of oil required by the oil-requiring device 12, the oil pressure in the oil passage 72 will be equal to or greater than the oil pressure in the oil passage 31, and the check valve 64 will be closed.

[0065] Furthermore, when the manual valve 65 is in the first operating state or the second operating state, if the port 43 and the port 44 are connected and the amount of oil discharged from the outlet 25 to the oil passage 28 increases, the amount of oil sent to the oil passage 61 increases. Then, if the oil pressure at the feedback port 59 exceeds a predetermined pressure, the spool of the relief valve 18 operates, connecting the port 58 and the port 57. Therefore, the oil in the oil passage 61 is sent to the oil passage 29 via the oil passage 60, and an increase in the oil pressure in the oil passage 61 is suppressed. Furthermore, if the oil pressure at the feedback port 59 exceeds the predetermined pressure and the spool of the relief valve 18 operates, the biasing force applied to the piston 37 by the spring 56 increases.

[0066] Therefore, the pressure in the hydraulic chamber 38 increases, which is necessary to operate the piston 37 so as to reduce the discharge rate of the variable displacement oil pump 11. In other words, in a situation where the discharge rate of the variable displacement oil pump 11 has been reduced to the extent that the hydraulic pressure at the feedback port 59 exceeds a predetermined pressure and the spool of the relief valve 18 operates, it is possible to reliably prevent the amount of oil discharged from the variable displacement oil pump 11 from decreasing further.

[0067] (3) Example of manual valve in neutral state Examples of when the manual valve 65 is held in the neutral state include when the stopped electric motor 32 is rotated, when the operating lever 73 is changed from the first operating position to the neutral position while the electric motor 32 is rotating, and when the operating lever 73 is changed from the second operating position to the neutral position while the electric motor 32 is rotating.

[0068] When the manual valve 65 is held in the neutral position, both the supply port 75 and the supply port 76 are closed, and the inlet port 74 and the discharge port 77 are connected. Therefore, oil is not supplied from the oil passage 72 to the oil-requiring device 12, and the operating members of the oil-requiring device 12 are stopped. In addition, the oil in the oil passage 72 is sent to the oil passage 78 via the inlet port 74 and the discharge port 77.

[0069] Furthermore, when the manual valve 65 is held in a neutral state and the oil pressure in the oil passage 31 exceeds the first predetermined oil pressure, the action and operation of the first circuit section 13 and the action and operation of the relief valve 63 are basically the same as those described above.

[0070] Furthermore, when the operating lever 73 is stopped in the neutral position, the controller 99 can control the duty ratio of the solenoid valve 83 to a value higher than 0%. When the controller 99 controls the duty ratio of the solenoid valve 83 to a value higher than 0%, the spool of the solenoid valve 83 operates against the biasing force of the spring 98, and the input port 95 and the output port 96 are connected.

[0071] As a result, oil discharged from the variable displacement oil pump 89 to the oil passage 88 is supplied to the hydraulic chamber 38 via the oil passage 93 and the oil passage 40. Then, the hydraulic pressure of the oil supplied from the oil passage 45 through the oil passage 39 and the hydraulic pressure of the oil supplied via the oil passage 40 are both transmitted to the hydraulic chamber 38, and the hydraulic pressure of the hydraulic chamber 38 increases. Here, the first hydraulic pressure of the hydraulic chamber 38 when the operating lever 73 is stopped at the neutral position is higher than the second hydraulic pressure when the operating lever 73 is stopped at the first operating position or the second operating position and oil from the oil passage 45 is supplied to the hydraulic chamber 38.

[0072] As a result, when the control lever 73 is stopped in the neutral position, the inclination angle θ1 of the swash plate 22 shown in FIG. 2 is reduced from the inclination angle θ2 of the swash plate 22 when the control lever 73 is stopped in the first or second operation position and oil in the oil passage 45 is supplied to the hydraulic chamber 38. In other words, the oil discharge rate of the variable displacement oil pump 11 when the control lever 73 is stopped in the neutral position is reduced from the oil discharge rate of the variable displacement oil pump 11 when the control lever 73 is stopped in the first or second operation position. For example, by controlling the duty ratio of the solenoid valve 83, the oil discharge rate of the variable displacement oil pump 11 when the control lever 73 is stopped in the neutral position can be adjusted within a range of 0% to 10% of the maximum oil discharge rate of 100%.

[0073] Therefore, when the operating lever 73 is stopped in the neutral position, the power consumed by the electric motor 32 is reduced compared to the power consumed by the electric motor 32 when the operating lever 73 is stopped in the first operating position or the second operating position. Fig. 4 shows an example of the change over time in the value of the current supplied to the electric motor 32. Fig. 4 shows a current value A1 when the operating lever 73 is stopped in the neutral position, and a current value A2 when the oil discharge rate of the variable displacement oil pump 11 is at its maximum. The current value A1 is lower than the current value A2, and there is a difference of a predetermined value X1 between them.

[0074] In addition, when the operating lever 73 is stopped in the neutral position, the noise generated by the variable displacement oil pump 11 is reduced compared to the noise generated by the variable displacement oil pump 11 when the operating lever 73 is stopped in the first operating position or the second operating position.

[0075] Furthermore, the temperature of the variable displacement oil pump 11 when the operating lever 73 is stopped in the neutral position can be kept lower than the temperature of the variable displacement oil pump 11 when the operating lever 73 is stopped in the first operating position or the second operating position.

[0076] Furthermore, the controller 99 determines whether the operating lever 73 is stopped in the neutral position by processing the signal output from the proximity switch 100. In other words, the controller 99 can indirectly determine whether the manual valve 65 connects or disconnects the oil passage 31 from the oil passage 79. Therefore, when the manual valve 65 disconnects the oil passage 31 from the oil passage 79, the oil discharge amount of the variable displacement oil pump 11 is reduced.

[0077] Furthermore, both pistons 33, 37 can be operated by the hydraulic pressure of the oil discharged from the variable displacement oil pump 11. This eliminates the need for a dedicated actuator to operate the pistons 33, 37. Also, a single variable displacement oil pump 89 is provided that discharges the oil supplied to the hydraulic chamber 38 via the solenoid valve 83. This prevents an increase in the number of parts in the hydraulic control device 10 and also prevents the structure from becoming complicated.

[0078] Furthermore, the oil discharged from the variable displacement oil pump 89 is supplied to the hydraulic chamber 38. Therefore, when the operating lever 73 is in the neutral position, the existing hydraulic chamber 38 can be used to reduce the amount of oil discharged from the variable displacement oil pump 11. This prevents the structure of the hydraulic control device 10 from becoming complicated.

[0079] (Example 2 of the third circuit section) 5 shows a second specific example of the third circuit unit 15. The third circuit unit 15 may have a solenoid valve 120, a relief valve 121, and a check valve 122. The solenoid valve 120 has a spool, an electromagnetic coil, an input port 103, an output port 104, a drain port 105, and a spring 106. The input port 103 is connected to the oil passage 88, and the output port 104 is connected to the oil passage 110. The drain port 105 is connected to the oil tank 27 via the oil passage 97.

[0080] Also provided is an oil pump 107 driven by the electric motor 92, and the oil pump 107 has an intake port 108 and an outlet port 109. The intake port 108 is connected to the oil tank 27. The outlet port 109 is connected to the oil passage 88. The rotation speed of the electric motor 92 is controlled to a constant value by a controller 99 shown in FIG. 1. When the electric motor 92 rotates, the oil pump 107 draws oil from the oil tank 27 through the intake port 108 and discharges the oil from the outlet port 109 to the oil passage 88.

[0081] The controller 99 controls the supply of power (ON) to the electromagnetic coil of the solenoid valve 120 and the interruption of power (OFF) to the electromagnetic coil. The solenoid valve 120 can be continuously switched ON and OFF. The solenoid valve 120 can also linearly control the ratio of ON time to OFF time within a given period of time, i.e., the duty ratio. The auxiliary storage device 99D stores information and data for controlling the solenoid valve 120.

[0082] When the solenoid valve 120 is turned off, the spool is stopped at the standby position by the biasing force of the spring 106. As a result, the input port 103 and the drain port 105 are connected, and the output port 104 is blocked. Therefore, the oil in the oil passage 88 is returned to the oil tank 27 via the input port 103 and the drain port 105.

[0083] When the solenoid valve 120 is turned on, a magnetic attractive force is generated, causing the spool to move against the biasing force of the spring 106, connecting the input port 103 to the output port 104. Also, the drain port 105 is closed. Therefore, oil in the oil passage 88 is supplied to the oil passage 110.

[0084] The relief valve 121 has a spool, a spring 111, ports 112 and 113, and a feedback port 114. The port 112 is connected to the oil passage 110. The port 112 is connected to the feedback port 114 by an oil passage 115. The port 113 is connected to the oil tank 27 via an oil passage 97.

[0085] When the pressure in oil passage 110 is lower than a predetermined value, relief valve 121 closes port 112 and port 113. When the pressure in oil passage 110 is equal to or higher than a predetermined value, relief valve 121 connects port 112 and port 113. As a result, oil in oil passage 110 is discharged to oil passage 97 through ports 112 and 113. This suppresses an increase in oil pressure in oil passage 110.

[0086] The controller 99 may arbitrarily control the duty ratio of the solenoid valve 120 within a range of 0% to 100% by PWM (Pulse Width Modulation) control of a switch circuit connected to the electromagnetic coil of the solenoid valve 120. Assuming that the oil discharge amount of the oil pump 107 is constant, as the duty ratio of the solenoid valve 120 increases, the amount of oil supplied from the oil passage 88 to the oil passage 110 increases.

[0087] When the controller 99 controls the duty ratio of the solenoid valve 120 to 0%, the output port 104 is closed and the amount of oil supplied from the oil passage 88 to the oil passage 110 is minimized.

[0088] The inlet of check valve 122 is connected to oil passage 110, and the outlet of check valve 122 is connected to oil passage 40. Check valve 122 is open in the direction in which oil is supplied from oil passage 110 to oil passage 40, and is closed in the direction in which oil flows back from oil passage 40 to oil passage 110. Check valve 122 is open when the oil pressure in oil passage 40 is lower than the oil pressure in oil passage 110. Check valve 122 is closed when the oil pressure in oil passage 40 is equal to or higher than the oil pressure in oil passage 110.

[0089] 1. Also, when the third circuit section 15 shown in FIG. 4 is provided as the third circuit section 15 shown in FIG. 1, the same effects as those described above can be obtained.

[0090] (Other explanations) An example of the technical meaning of the matters described in this embodiment is as follows: The hydraulic control device 10 is an example of a hydraulic control device. The electric motor 32 is an example of an electric motor. The variable displacement oil pump 11 is an example of a variable displacement oil pump. The swash plate 22 is an example of an operating member. The oil passage 31 is an example of a first oil passage. The oil passages 79 and 80 are an example of a second oil passage. The manual valve 65 is an example of a switching valve. The first control cylinder 16 is an example of a first operating force imparting mechanism. The second control cylinder 17 is an example of a second operating force imparting mechanism. The hydraulic chamber 38 is an example of a first hydraulic chamber. The first predetermined hydraulic pressure is an example of a predetermined hydraulic pressure.

[0091] The hydraulic chamber 34 is an example of a second hydraulic chamber. Ports 42, 53 and ports 47, 50 are an example of a third oil passage. The first control valve 19 and the second control valve 20 are both spool valves and are an example of a control valve. The solenoid valve 83 is an example of an oil supply mechanism. The operating lever 73 is an example of an operating member. The controller 99 is an example of a controller. The piston 33 is an example of a first piston. The piston 37 is an example of a second piston. The variable displacement oil pump 89 and the oil pump 107 are examples of an auxiliary oil pump. The input port 95 and the output ports 96, 104 are an example of a fourth oil passage. The proximity switch 100 is an example of a sensor.

[0092] This embodiment is not limited to those disclosed using the drawings, and various modifications are possible without departing from the spirit of the present invention. For example, the operating member may be any member that can be operated by an operator, including an operating lever, an operating button, an operating switch, an operating knob, etc. The oil passage is a path through which oil flows, including an oil passage, a passage, an opening, a port, etc. The sensor that detects the operating state of the operating member and outputs a signal may be either a non-contact sensor or a contact sensor. Non-contact sensors include proximity switches, laser sensors, color sensors, eddy current displacement sensors, etc. The contact sensor has a contact that comes into contact with an object. [Industrial Applicability]

[0093] The present disclosure can be used as a hydraulic control device capable of controlling the discharge amount of a variable displacement oil pump. [Explanation of symbols]

[0094] 10...hydraulic control device, 11,89...variable displacement oil pump, 16...first control cylinder, 17...second control cylinder, 19,20...control valve, 22...swash plate, 31,79,80...oil passage, 65...manual valve, 32...electric motor, 33,37...piston, 34,38...hydraulic chamber, 42,47,50,53...port, 73...operating lever, 83...solenoid valve, 95...input port, 96,104...output port, 99...controller, 107...oil pump

Claims

1. a variable displacement oil pump that is driven by the rotational force of the electric motor and discharges oil to be supplied to an oil-requiring device; A hydraulic control device having a first oil passage through which oil is discharged from the variable displacement oil pump; a second oil passage connected to the first oil passage and supplying oil discharged into the first oil passage to the oil-requiring device; a switching valve that connects and disconnects the first oil passage and the second oil passage; an operating member provided in the variable displacement oil pump and operable to change the oil discharge amount; a first operating force applying mechanism that is operated by the hydraulic pressure of the oil discharged from the variable displacement oil pump and applies an operating force to the operating member in a direction that increases the oil discharge amount of the variable displacement oil pump; a second operating force applying mechanism that is operated by the hydraulic pressure of the first hydraulic chamber and applies an operating force to the operating member in a direction that reduces the amount of oil discharged from the variable displacement oil pump; a third oil passage that sends a portion of the oil in the first oil passage to the first hydraulic chamber; a control valve that opens and closes the third oil passage; and The control valve a first state in which the first oil passage and the second oil passage are connected by the switching valve, and the third oil passage is closed when the oil pressure of the first oil passage is lower than a predetermined oil pressure; a second state in which the first oil passage and the second oil passage are blocked by the switching valve and the third oil passage is opened when the oil pressure in the first oil passage is equal to or higher than a predetermined oil pressure; The configuration allows switching between an oil supply mechanism capable of supplying oil to the first hydraulic chamber and arranged in parallel with the control valve; The hydraulic control device is configured such that the oil supply mechanism can change the amount of oil supplied to the first hydraulic chamber when the first oil passage and the second oil passage are blocked by the switching valve.

2. 2. The hydraulic control device according to claim 1, the oil supply mechanism is a solenoid valve that changes the amount of oil supplied to the first hydraulic chamber when a duty ratio of supplied power is changed; an operating member that is operated by an operator to change the state of the switching valve; a sensor that detects the operation state of the operation member and outputs a signal; a controller that processes a signal output from the sensor to determine whether the switching valve connects or disconnects the first oil passage and the second oil passage; and The controller is configured to control a duty ratio of power supplied to the solenoid valve.

3. 3. The hydraulic control device according to claim 2, The first operating force imparting mechanism includes: A second hydraulic chamber; a first piston operated by hydraulic pressure in a second hydraulic chamber; and the second operating force imparting mechanism has a second piston operated by hydraulic pressure in the first hydraulic chamber, The control valve is configured to be operated by the hydraulic pressure of the oil discharged from the variable displacement oil pump to open and close the third oil passage.

4. 4. The hydraulic control device according to claim 3, an auxiliary oil pump that discharges oil to be supplied to the first hydraulic chamber; a fourth oil passage that supplies oil discharged from the auxiliary oil pump to the first hydraulic chamber; is further provided, The hydraulic control device is configured so that the solenoid valve opens and closes the fourth oil passage.

5. 4. The hydraulic control device according to claim 3, When the control valve is in a second state in which it opens the third oil passage, a portion of the oil in the first oil passage is supplied to the first hydraulic chamber, increasing the oil pressure in the first hydraulic chamber, which is then applied from the second piston to the operating member, and increasing the operating force in a direction that reduces the oil discharge amount of the variable displacement oil pump.

6. 2. The hydraulic control device according to claim 1, a hydraulic control device including an electric motor that is supplied with electricity to rotate and drive the variable displacement oil pump;

Images