Hydraulic pump system and control device

Abstract

The oil pressure pump system includes: an oil pressure pump capable of changing the discharge flow rate; a regulator device for adjusting the discharge flow rate of the oil pressure pump; an operating device having an operating tool; a lock switching input unit for releasing the locked state of the operating tool; a relief valve for adjusting the discharge pressure of the oil pressure pump by changing its opening area; and a control device for controlling the operation of the relief valve; when the control device satisfies a specified operating condition, the control device reduces the opening area of the relief valve to increase the discharge pressure of the oil pressure pump, and after the control device increases the discharge pressure of the oil pressure pump, the regulator device increases the discharge flow rate. The operating condition includes releasing the locked state of the operating tool through the lock switching input unit.

Description

Technical Field

[0001] The present invention relates to an oil pump system capable of adjusting the discharge flow rate of an adjustable oil pump. Background Art

[0002] In construction machinery and the like, there is an oil pump system capable of changing the discharge flow rate of an oil pump according to the driving state of an oil pressure actuator or the like. As an example of an oil pump system, for example, a technique as described in Patent Document 1 is known. In the oil pump system of Patent Document 1, a variable capacity type oil pump is provided, and the tilt angle of a swash plate is changed according to the driving state of an oil pressure actuator or the like, that is, the discharge flow rate of the oil pump is changed.

[0003] Prior Art Documents:

[0004] Patent Documents:

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-179199. Summary of the Invention

[0006] Problems to be Solved by the Invention:

[0007] In the oil pump system described in Patent Document 1, the tilt angle is changed by the pressure of the working oil discharged from the oil pump, that is, the discharge pressure. Therefore, sufficient rocking force cannot be obtained to change the tilt angle in a state where the discharge pressure of the oil pump is low. Therefore, it is necessary to wait for the discharge pressure to rise, and the followability of the discharge flow rate to the operation of the operating tool is low.

[0008] Therefore, an object of the present invention is to provide an oil pump system and a control device capable of further improving the followability of the discharge flow rate to the operation of an operating tool.

[0009] Means for Solving the Problems:

[0010] The oil pump system of the first invention includes: an oil pump capable of changing the discharge flow rate; a regulator device for adjusting the discharge flow rate of the oil pump; an operating device having an operating tool; a lock switching input unit for switching the locked state of the operating tool; a relief valve for adjusting the discharge pressure of the oil pump by changing its opening area; and a control device for controlling the operation of the relief valve; when a predetermined operating condition is satisfied, the control device reduces the opening area of the relief valve to increase the discharge pressure of the oil pump, and the regulator device increases the discharge flow rate of the oil pump after the control device increases the discharge pressure of the oil pump, and the operating condition includes releasing the locked state of the operating tool through the lock switching input unit.

[0011] According to the present invention, when the lock of the operating tool is released, the discharge pressure rises, so sufficient rocking force can be obtained to change the tilt angle when operating the operating tool. Therefore, the followability of the discharge flow rate to the operation amount is improved.

[0012] The control device of the second invention controls the operations of the regulator device and the unloading valve. Among them, the regulator device increases the discharge flow rate according to the boost of the discharge pressure of a variable displacement type hydraulic pump whose discharge flow rate can be changed. The unloading valve adjusts the discharge pressure of the hydraulic pump by changing its opening area, and switches the locked state of the operating tool according to the operation of the lock switching input part. When the specified operating conditions are met, the opening area of the unloading valve is reduced to increase the discharge pressure of the hydraulic pump. The operating conditions include releasing the locked state of the operating tool through the lock switching input part.

[0013] According to the second invention, when the lock of the operating tool is released, the discharge pressure rises. Therefore, sufficient rocking force can be obtained to change the tilt angle when operating the operating tool. As a result, the followability of the discharge flow rate to the operation amount is improved.

[0014] Advantages of the invention:

[0015] According to the first and second inventions, the followability of the discharge flow rate to the operation of the operating tool can be further improved.

[0016] Referring to the accompanying specification drawings, the above objects, other objects, features and advantages of the present invention will be clarified based on the following detailed description of the preferred embodiments. Description of the drawings

[0017] Figure 1 shows the hydraulic circuit of the hydraulic pump systems of the first and second embodiments;

[0018] Figure 2 is a graph showing the change of various state values over time in the hydraulic pump system of the first embodiment;

[0019] Figure 3 is a graph showing the change of various state values over time in the hydraulic pump system of the second embodiment. Detailed implementation manners

[0020] Hereinafter, the hydraulic pump systems 1 and 1A of the first and second embodiments related to the present invention will be described with reference to the specification drawings. In addition, the hydraulic pump systems 1 and 1A described below are only one embodiment of the present invention. Therefore, the present invention is not limited to the embodiments, and additions, deletions, and changes can be made without departing from the spirit of the invention.

[0021] [First embodiment]

[0022] In construction machinery such as hydraulic excavators, in order to drive hydraulic actuators (not shown) such as hydraulic cylinders and hydraulic motors, it is equipped with Figure 1The oil pressure drive system 2 shown. The oil pressure drive system 2 includes: an oil pressure pump system 1 and a direction control valve 3. The oil pressure pump system 1 includes: an oil pressure pump 11, a regulator device 13, an unloading valve 14, a control device 15, an operation device 16, and a lock switching input unit 17. The oil pressure pump 11 is rotationally driven by the engine E and discharges the working fluid. The oil pressure pump 11 is connected to the oil pressure actuator through the direction control valve 3, and the direction control valve 3 switches the direction and flow rate of the working fluid flowing in the oil pressure actuator. That is, the direction control valve 3 has a spool 3a, and the spool 3a cuts off between the oil pressure pump 11 and the oil pressure actuator at the neutral position. Also, the spool 3a can change the direction and flow rate of the working oil by moving from the neutral position, and by operating the spool 3a, the oil pressure actuator can operate at a required speed.

[0023] In addition, the oil pressure pump 11 can change the discharge capacity, and in this embodiment, it is a variable capacity type swash plate pump. That is, the oil pressure pump 11 has a swash plate 11a, and the discharge capacity can be changed by changing its tilt angle. Also, a regulator device 13 is provided on the swash plate 11a. In addition, the oil pressure pump 11 is not limited to a swash plate pump and can be a swash shaft pump. The regulator device 13 changes the tilt angle of the swash plate 11a to adjust the discharge capacity, and has a servo piston 21, a regulating valve 22, and a flow control proportional valve 23.

[0024] The servo piston 21 is connected to the swash plate 11a and changes the tilt angle of the swash plate 11a by moving in the axial direction thereof. More specifically, the servo piston 21 has two pressure receiving portions. The first pressure receiving portion formed on the small diameter receives the discharge pressure introduced into the first pressure receiving chamber 13a, and the second pressure receiving portion formed on the large diameter receives the control pressure introduced into the second pressure receiving chamber 13b. By the pressure acting on the first pressure receiving chamber 13a, the swash plate 11a swings toward the side where the tilt becomes larger, and by the pressure acting on the second pressure receiving chamber 13b, the swash plate 11a swings toward the side where it becomes smaller. Moreover, the servo piston 21 moves to the position where the forces acting on each pressure receiving portion are balanced. In this way, the position of the servo piston 21 can be adjusted by changing the control pressure, and the discharge flow rate can be increased or decreased. And, a regulating valve 22 is connected to the second pressure receiving chamber 13b to adjust the control pressure.

[0025] The regulating valve 22 has a spool 22a, a sleeve 22b, and a flow control piston 22c, and the control pressure is adjusted by moving the spool 22a. More specifically, a flow control proportional valve 23 is provided on the regulating valve 22. The flow control proportional valve 23 uses the discharge pressure of the oil pressure pump 11 as the primary pressure and outputs a secondary pressure corresponding to the command signal input thereto, that is, the working pressure. The working pressure acts on the spool 22a through the flow control piston 22c, and the spool 22a moves in the direction of increasing flow rate ( Figure 1 to the left direction, with the position of the spool 22a of Figure 1 being the right position) and the direction of decreasing flow rate ( Figure 1 to the right direction, with the position of the spool 22a of Figure 1The position of the spool 22a is moved to the left position). Further, when the spool 22a moves in the flow rate increasing direction, the second pressure receiving chamber 13b is connected to the storage tank 18, and the control pressure decreases. By this, the servo piston 21 moves toward the second pressure receiving chamber 13b side, and the tilt of the swash plate 11a increases, that is, the discharge amount increases. On the other hand, when the spool 22a moves in the flow rate decreasing direction, the second pressure receiving chamber 13b is connected to the discharge port 11b of the oil pressure pump 11, and the control pressure rises. By this, the servo piston 21 moves toward the first pressure receiving chamber 13a side, and the tilt of the swash plate 11a decreases, that is, the discharge amount decreases.

[0026] Further, a sleeve 22b interlocked with the servo piston 21 is externally mounted on the spool 22a. The sleeve 22b moves to a position where the thrust of the oil pressure in the second pressure receiving chamber 13b and the thrust of the oil pressure in the first pressure receiving chamber 13a are balanced (relative position corresponding to the spool 22a). In detail, the aforementioned control pressure is the pressure at the middle part of two series throttle parts (not shown) on the passage connecting the discharge port 11b of the oil pressure pump 11 to the storage tank 18. Thus, the servo piston 21 stops at the position corresponding to the spool 22a. In this way, the regulating valve 22 can move the spool 22a to a position corresponding to the command signal input to the flow control proportional valve 23, and change the discharge flow rate of the oil pressure pump 11 to a flow rate corresponding to the command signal.

[0027] As described above, the oil pressure pump system 1 configured as such includes a relief valve 14. The relief valve 14 is connected to the discharge port 11b of the oil pressure pump 11 in a form juxtaposed with the direction control valve 3, and is also connected to the storage tank 18. The relief valve 14 discharges the working oil of the flow rate to the storage tank 18 to unload the oil pressure pump 11, and also has the following functions. That is, in the present embodiment, an electromagnetic proportional valve 19 is provided on the relief valve 14. The electromagnetic proportional valve 19 outputs a pilot pressure according to the command signal input thereto, and the relief valve 14 changes the opening area according to the pilot pressure. By this, the working oil of the flow rate corresponding to the opening area of the relief valve 14 is discharged to the storage tank 18, and the discharge pressure of the oil pressure pump 11 is adjusted. The relief valve 14 having such a function is electrically connected to the control device 15.

[0028] The control device 15 is electrically connected to the direction control valve 3 and the flow control proportional valve 23 in addition to the electromagnetic proportional valve 19 of the relief valve 14, and outputs command signals to these valves 3, 19, 23 to control their operations. Further, the control device 15 is electrically connected to the operation device 16 and the lock switching input unit 17. The operation device 16 is used to operate the oil pressure actuator, which is an electric joystick in the present embodiment. In addition, the operation device 16 is not limited to the electric joystick, and may be a pilot operation valve, and is used in combination with a pressure sensor capable of obtaining the output pressure.

[0029] The operating device 16 has an operating lever 16a as an operating tool, and the control device 15 moves the spool 3a of the direction control valve 3 from the neutral position according to the operation amount of the operating lever 16a. By this, the hydraulic actuator operates according to the operation amount of the operating lever 16a. Also, the control device 15 outputs a pilot pressure corresponding to the operation amount of the operating lever 16a from the electromagnetic proportional valve 19 to close the unloading valve 14 or reduce the opening area. By this, the discharge pressure of the hydraulic pump 11 rises, and the first pressure receiving chamber 13a rises in pressure, so the discharge flow rate of the hydraulic pump 11 increases.

[0030] Also, the lock switching input unit 17 is a device for selecting whether the function of the operating device 16 is in a locked state, and in this embodiment, it is a lever or the like. In addition, the lock switching input unit 17 is not limited to a lever and may be a changeover switch or the like. When the lock switching input unit 17 is operated, the control device 15 switches the ON (open) and OFF (closed) of the locked state. When the locked state is ON, the control device 15 invalidates the operation of the operating lever 16a and maintains the spool 3a of the direction control valve 3 at the neutral position regardless of the operation amount of the operating lever 16a. On the other hand, when the locked state is OFF, the control device 15 enables the operation of the operating lever 16a and moves the spool 3a of the direction control valve 3 according to the operation amount of the operating lever 16a.

[0031] In the hydraulic pump system 1 configured as described above, in the neutral state where the operating lever 16a is in the neutral position, the control device 15 stops the output of the flow control proportional valve 23 and introduces the discharge pressure into the second pressure receiving chamber 13b. By this, the servo piston 21 moves toward the first pressure receiving chamber 13a side, and the discharge flow rate of the hydraulic pump 11 becomes the minimum flow rate. In addition, in the neutral state and when the locked state is ON (that is, when the working conditions described later are not satisfied), the control device 15 makes the opening area of the unloading valve 14 a prescribed first opening area (for example, an opening area of 80% or more of the maximum opening area), which is the maximum opening area in this embodiment, and makes the hydraulic pump 11 in the unloading state. By this, the control device 15 reduces the power loss in the hydraulic pump system 1. Moreover, when the locked state is switched from ON to OFF and the operating lever 16a is operated as shown in Figure 2 shown, the control device 15 performs the following processing. Also, Figure 2 In the vertical axes of the respective graphs shown, the lock state, the operation amount of the operating lever 16a, the opening area of the unloading valve 14, the discharge pressure of the hydraulic pump 11, and the discharge flow rate of the hydraulic pump 11 are shown in order from the top, and the horizontal axis represents the elapsed time. The same applies to the respective graphs of Figure 3 described later.

[0032] That is, when the control device 15 satisfies the specified operating conditions, that is, when the locked state is switched to OFF (i.e., the locked state is released), the unloading valve 14 is put into the standby state. Here, the standby state means that the electromagnetic proportional valve 19 is operated and the opening area of the unloading valve 14 is closed to a specified second opening area (see Figure 2 at the time t11). Further, the second opening area is an area such that the discharge pressure of the oil pressure pump 11 is, for example, 0.6 MPa or more and 5.0 MPa or less, specifically 1% or more and less than 30% of the maximum opening area, and in this embodiment, it is 5% of the maximum opening area. By being in the standby state, the discharge pressure of the oil pressure pump 11 can be increased, and the pressurized working fluid can be introduced into the first pressure receiving chamber 13a. By means of this, sufficient rocking force can be obtained when the operation lever 16a is operated to change the tilt angle of the swash plate 11a of the oil pressure pump 11, and the followability of the discharge flow rate of the oil pressure pump 11 to the operation amount can be improved.

[0033] Also, when the operation lever 16a is operated in a state where the operating conditions are satisfied, when the operation amount of the operation lever 16a exceeds a first specified amount (see Figure 2 at the time t12), the control device 15 increases the output of the electromagnetic proportional valve 19 according to the operation amount, and further reduces the opening area of the unloading valve 14. Therefore, the discharge flow rate corresponding to the operation amount is discharged from the oil pressure pump 11. Moreover, after the operation amount exceeds a second specified amount (see Figure 2 at the time t13) and reaches a third operation amount (see Figure 2 at the time t14), the control device 15 completely closes the unloading valve 14. Further, the second specified amount is the operation amount at which the direction control valve 3 opens and starts supplying the working oil to the oil pressure actuator.

[0034] In this way, by starting to close the unloading valve 14 at the first specified amount where the operation amount is less than the second specified amount, the discharge flow rate can be increased rapidly.

[0035] [Second Embodiment]

[0036] The oil pressure pump system 1A of the second embodiment has the same structure as the oil pressure pump system 1 of the first embodiment, and the processing performed by the control device 15A is different. Therefore, regarding the oil pressure pump system 1A of the second embodiment, mainly the processing performed by the control device 15A will be described, and the same reference numerals as those of the structure of the oil pressure pump system 1 of the first embodiment are used for the structure and the description is omitted.

[0037] In the oil pressure pump system 1A, the operating conditions include operating the operation lever 16a and the operation amount being equal to or more than the first specified amount. After the locked state is switched to OFF as shown in Figure 3 (see Figure 3At time t21), the control device 15A also maintains the opening area of the unloading valve 14 at the maximum opening area. By doing so, power loss in the oil pressure pump system 1A can be suppressed. After that, when the operating lever 16a is operated and the operation amount becomes the first specified amount, the control device 15A places the unloading valve 14 in a standby state (see Figure 3 at time t22). After that, when the operation amount further increases, the unloading valve 14 is gradually closed further according to the operation amount (see Figure 3 at time t23 for reference), and when the operation amount exceeds the second specified amount (see Figure 3 at time t23) and reaches the third operation amount (see Figure 3 at time t24), the control device 15A completely closes the unloading valve 14.

[0038] The oil pressure pump system 1A configured in this way, in addition to reducing power loss before the operation of the operating lever 16a as described above, exhibits the same effects as the oil pressure pump system 1 of the first embodiment.

[0039] [Other Embodiments]

[0040] In the oil pressure pump systems 1 and 1A of this embodiment, the unloading valve 14 is connected to the oil pressure pump 11 in a form juxtaposed with the direction control valve 3, but it is not necessary to be connected in this way. For example, when the direction control valve 3 has a central bypass passage, the unloading valve 14 can be interposed on the downstream side of the direction control valve 3 in this central bypass passage, and the same effects can be achieved if there is a valve independent of the direction control valve 3 and capable of boosting the discharge pressure of the oil pressure pump 11 (that is, a valve capable of reducing the passage area). Also, the structure of the regulator device 13 is not limited to the aforementioned structure, and it can be a structure capable of adjusting the discharge flow rate using the discharge pressure of the oil pressure pump 11.

[0041] Also, in the oil pressure pump systems 1 and 1A of this embodiment, the second opening area of the unloading valve 14 is a fixed value, but the second opening area can also be changed according to the rotational speed of the oil pressure pump 11. That is, it can also be that the control device 15 acquires the rotational speed of the oil pressure pump 11 and changes the second opening area accordingly.

[0042] Based on the above description, for those skilled in the art, many improvements and other embodiments of the present invention become clear. Therefore, the above description should only be interpreted as illustrative and is provided for the purpose of teaching those skilled in the art the best mode of implementing the present invention. As long as the spirit of the present invention is not departed from, the details of its specific structure and / or function can be substantially changed.

[0043] Symbol Explanation:

[0044] 1, 1A Oil pressure pump system

[0045] 11 Oil pressure pump

[0046] 13 Regulator device

[0047] 14 Unloading valve

[0048] 15, 15A Control device

[0049] 16 Operating device

[0050] 16a Operating lever (operating tool)

[0051] 17 Locking switching input section.

Claims

1. An oil pressure pump system, comprising: An oil pressure pump capable of changing the discharge flow rate; A regulator device for adjusting the discharge flow rate of the oil pressure pump; An operating device having an operating tool; A lock switching input unit for switching the locked state of the operating tool; A relief valve for adjusting the discharge pressure of the oil pressure pump by changing its opening area; And A control device for controlling the operation of the relief valve; When the control device satisfies the specified operating conditions, the opening area of the relief valve is reduced to increase the discharge pressure of the oil pressure pump, After the control device increases the discharge pressure of the oil pressure pump, the regulator device increases the discharge flow rate of the oil pressure pump according to the increase in the discharge pressure of the oil pressure pump, The operating conditions include releasing the locked state of the operating tool through the lock switching input unit.

2. The oil pressure pump system according to claim 1, wherein The operating conditions further include that the operation amount of the operating tool is equal to or more than a specified amount.

3. The oil pressure pump system according to claim 1 or 2, wherein When the operating tool is operated in a state where the control device satisfies the operating conditions, the control device reduces the opening area of the relief valve according to the operation amount of the operating tool.

4. The oil pressure pump system according to claim 1 or 2, wherein When the control device does not satisfy the operating conditions, the control device makes the opening area of the relief valve maximum.

5. A control device, Control the regulator device and the operation of the unloading valve, where The regulator device increases the discharge flow rate according to the increase in the discharge pressure of a variable displacement type oil pressure pump capable of changing the discharge flow rate, and the relief valve adjusts the discharge pressure of the oil pressure pump by changing its opening area, Switches the locked state of the operating tool according to the operation of the lock switching input unit, When the specified operating conditions are satisfied, the opening area of the relief valve is reduced to increase the discharge pressure of the oil pressure pump, and then the regulator device increases the discharge flow rate of the oil pressure pump according to the increase in the discharge pressure of the oil pressure pump; The operating conditions include releasing the locked state of the operating tool through the lock switching input unit.

6. The control device according to claim 5, wherein The operating conditions further include that the operation amount of the operating tool is equal to or more than a specified amount.

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