Pressure compensated valve

Abstract

In order to realize the improvement of responsiveness, a throttle passage (226) which is always communicated with the pump port (111) is formed in a spool portion (220) of a valve body (20), a supply pressure communication passage (124), (114), (125) which is closed by the spool portion (220) to block the communication between the throttle passage (226) and a load pressure chamber (221) in a case where the pump port (111) is closed by the spool portion (220) using the force of a load pressure spring (225) between the pump port (111) and a cylinder port (112), on the other hand, is provided in a housing (10), and the communication between the throttle passage (226) and the load pressure chamber (221) is performed via a throttle hole (229) in a case where the spool portion (220) is moved by a prescribed stroke in an opening direction, a delivery pressure chamber (223) which presses the spool portion (220) in a closing direction in a case where the internal pressure is increased is provided between the spool portion (220) and the housing (10), and a delivery pressure passage (213) which is always communicated between the delivery pressure chamber and the cylinder port (112) is connected to the delivery pressure chamber (223).

Description

Technical Field

[0001] This invention relates to a pressure compensation valve used in a drive circuit that actuates multiple fluid pressure actuators. Background Technology

[0002] For example, in a drive circuit that uses a single hydraulic pump to operate multiple hydraulic actuators, a pressure compensation valve is sandwiched between the hydraulic pump and each hydraulic actuator. As such a pressure compensation valve, for example, the pressure compensation valve described in Patent Document 1 is provided. This pressure compensation valve is configured such that, through the appropriate movement of a movable sleeve provided on the outer periphery of the valve body, it selects the high-pressure side of its own outlet port pressure (the load pressure of the corresponding hydraulic actuator) and the control pressure from other pressure compensation valves, and applies the selected high-pressure side pressure as the back pressure of the valve body. According to the drive circuit equipped with the pressure compensation valve, even when the load pressures of multiple hydraulic actuators are different, it is possible to prevent oil from being supplied only to the hydraulic actuator with the low load pressure side.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-205502 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, when multiple hydraulic actuators are operated simultaneously, the load pressure of each actuator may vary. In this case, in the pressure compensation valve described above, the back pressure applied to the valve body does not change without the movement of the movable sleeve, so it may not be the preferred option considering the responsiveness of the valve body. In particular, if a high load pressure is suddenly generated on a hydraulic actuator with a low load pressure due to interference or other factors, it is difficult to close the valve body immediately, which may lead to problems such as applying high load pressure to the pressure supply source.

[0008] In view of the above-mentioned actual situation, the present invention aims to provide a pressure compensation valve that can achieve improved responsiveness.

[0009] Solution for solving the problem

[0010] To achieve the above objectives, the pressure compensation valve of the present invention comprises: a housing having an inlet port and an outlet port; a valve body for opening and closing between the inlet port and the outlet port; and a load pressure spring sandwiched between the housing and the valve body, applying force to the valve body in a closing direction; a load pressure chamber provided between the valve body and the housing, which presses against the valve body in a closing direction when the internal pressure increases; the pressure compensation valve controls the supply of fluid from the inlet port to the outlet port based on the supply pressure of fluid applied to the inlet port and the control pressure applied to the load pressure chamber; characterized in that the valve body comprises: a poppet portion that allows fluid to flow from the inlet port to the outlet port, and on the other hand, blocks fluid from flowing from the outlet port to the inlet port; and a slide valve portion that is slidably disposed on the housing with its base end facing the load pressure chamber; the front of the slide valve portion... The end is held in contact with the lifting valve by the force of the load pressure spring. A throttling passage is provided on the slide valve in such a way that it is always connected to the inlet port and has a sliding opening between it and the housing. A supply pressure connection passage is provided in the housing. When the lifting valve closes the inlet port and the outlet port by the force of the load pressure spring, the supply pressure connection passage is closed by the slide valve, blocking the throttling passage from the load pressure chamber. On the other hand, when the slide valve moves a predetermined stroke in the opening direction, the supply pressure connection passage connects the throttling passage to the load pressure chamber. An outlet pressure chamber is provided between the lifting valve and the housing. When the internal pressure of the outlet pressure chamber increases, it presses the lifting valve in the closing direction. An outlet pressure passage is connected to the outlet pressure chamber, always connecting the outlet pressure chamber to the outlet port.

[0011] Invention Effects

[0012] According to the present invention, the pressure at its own outlet port and the high-pressure side of the control pressure from other pressure compensation valves are selected based on the position of the valve body and applied to the load pressure chamber, thus providing an advantage in terms of valve body responsiveness. Furthermore, in the event of a sharp increase in pressure at the outlet port while the valve body is open, this pressure is applied to the outlet pressure chamber through the outlet pressure passage, causing the valve section to immediately move in the closing direction. Therefore, even when a fluid pressure actuator that is low relative to the load pressure rapidly generates a high load pressure, problems such as the application of this high load pressure to the pressure supply source are avoided. Attached Figure Description

[0013] Figure 1This is a diagram showing a hydraulic drive circuit that uses a pressure compensation valve as an embodiment of the present invention.

[0014] Figure 2 It means Figure 1 A cross-sectional view of the structure of a pressure compensation valve.

[0015] Figure 3 Is Figure 2 A cross-sectional view of the pressure compensation valve in the state where the valve body is initially open.

[0016] Figure 4 Is Figure 2 A cross-sectional view of the pressure compensation valve after the valve body is open and the flow path is connected to the load pressure chamber.

[0017] Figure 5 It is the lifting valve section from Figure 4 The diagram shows a cross-sectional view of the state after the current state is turned off. Detailed Implementation

[0018] Hereinafter, preferred embodiments of the pressure compensation valve of the present invention will be described in detail with reference to the accompanying drawings.

[0019] Figure 1 This diagram illustrates a hydraulic drive circuit employing a pressure compensation valve as an embodiment of the present invention. The hydraulic drive circuit illustrated here is used to actuate two hydraulic cylinder actuators 2A and 2B via a single hydraulic pump 1. The hydraulic pump 1 is a variable-capacity pump equipped with a capacity setting unit 3 that varies the discharge volume according to an applied control pressure. The hydraulic cylinder actuators 2A and 2B are compound actuators that operate by selectively supplying oil to the rod chamber 2a and the bottom chamber 2b. A directional switching valve 4 and a pressure compensation valve 5 are respectively provided between the hydraulic pump 1 and the hydraulic cylinder actuators 2A and 2B. The directional switching valve 4 is respectively sandwiched between the hydraulic pump 1 and the hydraulic cylinder actuator 2A and between the hydraulic pump 1 and the hydraulic cylinder actuator 2B, selectively connecting the hydraulic pump 1 to the rod chamber 2a and the bottom chamber 2b of the hydraulic cylinder actuators 2A and 2B. The pressure compensation valve 5 is sandwiched between the directional switching valve 4 and the hydraulic pump 1, controlling the oil supply to each hydraulic cylinder actuator 2A and 2B. The structure of the pressure compensation valve 5 will be described in detail below, along with the characteristic features of the invention. It should be noted that the structure of the pressure compensation valve 5 is common to both hydraulic cylinder actuators 2A and 2B; therefore, the structure of the pressure compensation valve 5 connected to hydraulic cylinder actuator 2A will be described below.

[0020] Figure 2 This is a diagram showing the specific structure of the pressure compensation valve 5. As shown in the figure, the pressure compensation valve 5 of this embodiment is configured to include a housing 10 and a valve body 20.

[0021] The housing 10 includes: a housing body 110 having a pump port (inlet port) 111 and a cylinder port (outlet port) 112, and having a guide hole 113 configured to communicate the pump port 111 and the cylinder port 112; and a plug 120 fitted into the guide hole 113 of the housing body 110.

[0022] like Figure 1 As shown, the pump port 111 of the housing body 110 is connected to the discharge port 1a of the hydraulic pump 1 via a branch supply passage 6. The cylinder port 112 is connected to the input port 4a of the directional switching valve 4 via a supply passage. Figure 2 As shown, the guide hole 113 is formed to communicate with the pump port 111 via the cylinder port 112 from the outer surface of the housing body 110. The portion of the guide hole 113 from the outer surface of the housing body 110 to the cylinder port 112 has a substantially constant inner diameter. In the portion of the guide hole 113 from the cylinder port 112 to the pump port 111, a tapered valve seat 113a is formed such that the inner diameter gradually decreases towards the pump port 111. An internal thread groove 113b is formed in the portion of the guide hole 113 near the outer surface of the housing body 110.

[0023] The plug 120 has: a cylindrical insertion portion 121 having an outer diameter that engages with a guide hole 113 in the housing body 110; and a larger diameter flange portion 122 disposed at the base end of the insertion portion 121. An external thread 121a is provided in the insertion portion 121 near the outer periphery of the flange portion 122. The axial dimension of the insertion portion 121 is set to be shorter than the length of the guide hole 113. The plug 120 is installed in the housing body 110 with the flange portion 122 abutting against the outer surface by inserting the front end of the insertion portion 121 into the guide hole 113 and screwing the external thread 121a into the internal thread groove 113b of the guide hole 113. As can be seen from the drawings, the front end face of the insertion portion 121 terminates near the front side of the cylinder port 112.

[0024] The insertion portion 121 of the plug 120 described above is provided with a slide valve hole 123, a first passage 124, and a second passage 125. The slide valve hole 123 is a circularly shaped opening formed along the axis of the insertion portion 121 from the end face of the insertion portion 121, and is configured to have a constant inner diameter. The inner diameter of the slide valve hole 123 is set to be the same as, or smaller than, the inner diameter of the portion 113c in the guide hole 113 that opens at the pump port 111. The first passage 124 and the second passage 125 are small-diameter holes formed in a manner that extends from the outer peripheral surface of the insertion portion 121 to the inner peripheral surface of the slide valve hole 123. The first passage 124 extends radially at approximately a right angle to the axis of the insertion portion 121 and is formed in the portion of the insertion portion 121 closer to the front end of the external thread 121a. In the illustrated example, a plurality of first passages 124 are formed radially. The second passage 125 extends obliquely from the outer peripheral surface of the insertion portion 121 toward the center, gradually becoming the base end side, and is uniquely formed in the insertion portion 121 such that the opening on the outer peripheral surface is located between the first passage 124 and the external thread 121a. The first passage 124 and the second passage 125 are interconnected via a load pressure port 114 located in the housing body 110, which is further forward than the internal thread groove 113b. The load pressure port 114 is an annular space formed at the point when the insertion portion 121 of the plug 120 is fitted into the guide hole 113 by providing a recess on the inner peripheral surface of the guide hole 113. Figure 1 As shown, the load pressure port 114 is interconnected with the load pressure port 114 of the pressure compensation valve 5 located in another hydraulic cylinder actuator 2B via the load pressure passage 7. Furthermore, the load pressure passage 7 is connected to the capacity setting unit 3 of the hydraulic pump 1 and communicates with the tank T via the tank throttling section n. It should be noted that... Figure 2 In the attached drawings, reference numerals R1 and R2 are oil seals located between the guide hole 113 of the housing body 110 and the insertion part 121 of the plug 120.

[0025] The valve body 20 opens and closes the connection between the pump port 111 and the cylinder port 112 by operating relative to the housing 10. In this embodiment, the valve body 20 is configured to include a lifting valve section 210, a spool valve section 220, and a load checking spring 230.

[0026] The lifting valve section 210 allows oil to be supplied from the pump port 111 to the cylinder port 112, while preventing oil from flowing from the cylinder port 112 to the pump port 111. In this embodiment, a lifting valve section 210 with a cylindrical base end that fits into the guide hole 113 and a tapered front end that contacts the surface of the valve seat 113a is used. This lifting valve section 210 can be slidably fitted into the guide hole 113 via its base end and can move along its axis with the guide hole 113 as a guide. That is, the dimension of the lifting valve section 210 along its axis is set in such a way that even when it is in contact with the valve seat 113a, a gap is generated between it and the front end of the plug 120, and it can be moved to a state separated from the valve seat 113a by moving along the axis of the guide hole 113. The lifting valve section 210 has a fitting hole 211, an inlet hole 212, and a pressure outlet passage 213.

[0027] The fitting hole 211 opens only on the base end face of the cylindrical portion formed in the lifting valve section 210, has a circular cross-section with a constant inner diameter, and is formed along the axis of the lifting valve section 210. The inner diameter of the fitting hole 211 is smaller than the inner diameter of the slide valve hole 123 provided in the plug 120. One end of the inlet hole 212 opens on the front end face of the lifting valve section 210, and the other end opens in the fitting hole 211. Multiple inlet holes 212 are formed at equal intervals on a circumference centered on the axis of the lifting valve section 210. These inlet holes 212 function in such a way that even when the lifting valve section 210 abuts against the valve seat 113a, that is, when the lifting valve section 210 closes the cylinder port 112 and the pump port 111, the pump port 111 remains connected. The pressure outlet passage 213 is a groove-shaped cut extending along the axis of the outer peripheral surface of the lifting valve section 210, and multiple such cuts are formed on the outer peripheral surface of the lifting valve section 210. These pressure outlet passages 213 function in such a way that the space between the cylinder port 112 and the portion of the guide hole 113 located on the side closer to the base end of the lifting valve section 210 is always connected.

[0028] The slide valve portion 220 is formed as a cylindrical shape with a circular cross-section. The base end of the slide valve portion 220 forms a load pressure chamber 221 between itself and the slide valve portion 220 by engaging with the slide valve hole 123 of the plug 120. The diameter of the front end of the slide valve portion 220 is smaller than that of the base end, and it is slidably engaged with the engagement hole 211 of the lifting valve portion 210. Although not explicitly shown in the figure, the gap between the engagement hole 211 and the front end of the slide valve portion 220 is set to be larger than the gap between the slide valve hole 123 and the base end of the slide valve portion 220, and larger than the gap between the guide hole 113 and the lifting valve portion 210.

[0029] The foremost portion of the slide valve section 220 has an outer diameter smaller than that of the fitting hole 211, forming a communication chamber 222 between it and the lifting valve section 210. This communication chamber 222 remains in communication with the inlet hole 212 of the lifting valve section 210 even when the front end face of the slide valve section 220 is in contact with the lifting valve section 210. Furthermore, an annular pressure outlet chamber 223 is formed between the front end of the slide valve section 220 and the guide hole 113 between the plug 120 and the lifting valve section 210. This pressure outlet chamber 223 remains in communication with the cylinder port 112 via the aforementioned pressure outlet passage 213. Regarding the slide valve section 220, its axial dimension is set to be shorter than the distance from the fitting hole 211 of the lifting valve section 210, which abuts against the valve seat 113a, to the base end face of the slide valve hole 123, allowing it to move axially between them. However, the slide valve 220 is pressed by the load pressure spring 225 located in the load pressure chamber 221, and is maintained in a state where the front end face is always in contact with the lifting valve 210.

[0030] Additionally, a throttling passage 226 is provided in the slide valve section 220. The throttling passage 226 is configured to have an internal passage 227, an annular passage 228, and a throttling orifice 229. The internal passage 227 is a straight line formed along the axial portion of the slide valve section 220 and is configured to have a relatively large diameter. The base end of the internal passage 227 is closed, while the front end of the internal passage 227 communicates with the communication chamber 222 via a plurality of radially connected holes 227a. The annular passage 228 is formed in an annular shape on the outer peripheral surface of the slide valve section 220, in a portion that engages with the slide valve hole 123 of the plug 120, and is formed between the slide valve section 220 and the plug 120. This annular passage 228 is formed at a position further forward than the first passage 124 provided in the plug 120 when the lifting valve section 210 abuts against the valve seat 113a and the front end face of the slide valve section 220 abuts against the lifting valve section 210. When the slide valve portion 220 moves from this state towards the base end, before the base end of the slide valve portion 220 abuts against the plug 120, the annular passage 228 and the first passage 124 are opposite each other and can communicate with each other. The diameter of the throttling orifice 229 is smaller than that of the inner passage 227, and it has an inner diameter larger than that of the can throttling portion n. It is uniquely formed in the slide valve portion 220 when it is communicating between the annular passage 228 and the inner passage 227. In the figure, reference numeral R3 is a sealing unit provided between the slide valve portion 220 and the plug 120, and reference numeral R4 is a sealing unit provided between the slide valve portion 220 and the lifting valve portion 210. As these sealing units R3 and R4, for example, a sealing unit composed of an O-ring and a ring made of PTFE (polytetrafluoroethylene) can be used.

[0031] The load check spring 230 is sandwiched between the lifting valve section 210 and the slide valve section 220 in the outlet pressure chamber 223, thereby preventing the lifting valve section 210 from moving accidentally when the cylinder port 112 becomes negative pressure and vibration is applied to the housing body 110. In this embodiment, the load check spring 230 is used, and the set load is set to be smaller than that of the load pressure spring 225.

[0032] In the pressure compensation valve 5 configured as described above, such as Figure 2 As shown, when pump port 111 is closed by the lifting valve section 210, the throttling passage 226 and pump port 111 are also in a state of mutual communication via the inlet hole 212, the connecting chamber 222, and the connecting hole 227a. However, in this state, the throttling hole 229 is closed by the insertion section 121, thus blocking the connection between the load pressure chamber 221 and the throttling passage 226. As a result, as Figure 1 As shown, the load pressure chamber 221 becomes the tank pressure through the second passage 125, the load pressure port 114, and the load pressure passage 7. In other words, in Figure 2 In the shown state, the force that moves the valve body 20 in the closing direction is generated solely by the force of the load pressure spring 225, and the valve body 20 moves in the opening direction without overcoming the pressure of the load pressure chamber 221. Therefore, even considering the influence of the hemodynamic force due to the fluid flow when the lifting valve section 210 begins to open, it is possible to achieve the desired opening pressure during the lower supply pressure phase at the pump port 111. Figure 3 Moving the valve body 20 in the opening direction as shown reduces the horsepower loss of the hydraulic pump 1.

[0033] from Figure 3 The valve body 20 moves in the opening direction as shown in the diagram. Figure 4 As shown, when the annular passage 228 is positioned opposite the first passage 124, the throttling passage 226 communicates with the load pressure chamber 221 via the first passage 124, the load pressure port 114, and the second passage 125. As described above, the throttling passage 226 communicates with the pump port 111 via the connecting hole 227a, the connecting chamber 222, and the inlet hole 212. Therefore, in Figure 4 In the indicated state, the supply pressure of pump port 111 is applied to load pressure chamber 221, and the force generated by the pressure in load pressure chamber 221 and the force of load pressure spring 225 act in the direction of closing valve body 20. Thus, by balancing the force based on the supply pressure of pump port 111 (load pressure of hydraulic cylinder actuator 2A) with the force based on the pressure in load pressure chamber 221 and the force of load pressure spring 225, valve body 20 is properly actuated, controlling the flow rate of oil supplied to hydraulic cylinder actuator 2A.

[0034] Here, in Figure 1In the hydraulic drive circuit shown, the load pressure ports 114 of the two pressure compensation valves 5 are interconnected via the load pressure passage 7. Therefore, when the hydraulic cylinder actuators 2A and 2B perform a combined operation, a high-pressure supply pressure (load pressure) is applied to the load pressure chambers 221 of the two pressure compensation valves 5. In other words, in the pressure compensation valve 5 with a low-pressure supply pressure, the valve body 20 moves towards the closing direction using the high-pressure supply pressure applied to the load pressure chamber 221 via the load pressure port 114 and the second passage 125, thereby blocking the connection between the load pressure chamber 221 and the throttling passage 226. Therefore, even when the load pressures of the multiple hydraulic cylinder actuators 2A and 2B are different, it is possible to prevent oil from being supplied only to the hydraulic cylinder actuator with the low load pressure. Furthermore, since the load pressure chamber 221 is supplied via the load pressure port 114 and the second passage 125, no component that operates midway is required, thus providing an advantage in terms of responsiveness.

[0035] Furthermore, when the hydraulic cylinder actuators 2A and 2B perform a combined operation, if the load pressure reverses due to interference or other factors—in other words, if the load pressure of the hydraulic cylinder actuator on the low load pressure side rises sharply—the pressure at the high-pressure cylinder port 112 is applied to the outlet pressure chamber 223 through the outlet pressure passage 213. As a result, the lifting valve 210 immediately moves in the closing direction, blocking the connection between the cylinder port 112 and the pump port 111. Therefore, it is possible to prevent the application of high load pressure to the hydraulic pump 1.

[0036] It should be noted that in the above embodiment, the load check spring 230 is sandwiched between the lifting valve section 210 and the slide valve section 220, but it is not necessarily necessary to provide the load check spring 230. In addition, as the pressure outlet passage 213, an example is shown that it is only provided in the lifting valve section 210, but the pressure outlet passage can also be provided in the housing body 110 in such a way that the cylinder port 112 and the pressure outlet chamber 223 are always connected, or the pressure outlet passage can be provided in both the lifting valve section 210 and the housing body 110.

[0037] Explanation of reference numerals in the attached figures:

[0038] 5. Pressure compensating valve

[0039] 10. Shell

[0040] 20 Valve body

[0041] 110 Shell Body

[0042] 111 Pump Port

[0043] 112 cylinder port

[0044] 113 guide hole

[0045] 114 Load Pressure Port

[0046] 120 plug

[0047] 124 First Pathway

[0048] 125 Second Pathway

[0049] 210 Lifting Valve Section

[0050] 213 Derivation Pressure Path

[0051] 220 slide valve section

[0052] 221 Load Pressure Chamber

[0053] 223 Exhaust Pressure Chamber

[0054] 225 load compression spring

[0055] 226 sections of circulation road

[0056] 227 Internal Pathway

[0057] 228 Circular Pathway

[0058] 229 throttling orifice.

Claims

1. A pressure compensating valve, comprising: The housing has an inlet port and an outlet port; Valve body, which opens and closes between the inlet port and the outlet port; and A load-bearing pressure spring, clamped between the housing and the valve body, applies a force to the valve body in the closing direction. A load pressure chamber is provided between the valve body and the housing. When the internal pressure of the load pressure chamber increases, it presses in the direction of closing the valve body. The pressure compensation valve controls the fluid supply from the inlet port to the outlet port based on the supply pressure of the fluid applied to the inlet port and the control pressure applied to the load pressure chamber. Its features are, The valve body includes: The valve is actuated to allow fluid to flow from the inlet port to the outlet port, and conversely, to block fluid flow from the outlet port to the inlet port; and A slide valve portion is slidably disposed on the housing with its base end facing the load pressure chamber. The front end of the slide valve is held in contact with the lifting valve by the force of the load pressure spring. A throttling passage is provided on the slide valve section in such a way that it is always in communication with the inlet port and has an opening in the sliding portion between it and the housing. A supply pressure connection passage is provided in the housing. When the lifting valve is closed by the force of the load pressure spring, the supply pressure connection passage is blocked by the slide valve, thus blocking the throttling passage from the load pressure chamber. On the other hand, when the slide valve has moved a predetermined stroke in the opening direction, the supply pressure connection passage connects the throttling passage with the load pressure chamber. A pressure outlet chamber is provided between the lifting valve and the housing. When the internal pressure of the pressure outlet chamber increases, it presses the lifting valve toward the closing direction. A pressure outlet passage is connected to the pressure outlet chamber to keep the pressure outlet chamber connected to the pressure outlet port.

2. The pressure compensation valve according to claim 1, characterized in that, The housing includes: The housing body has the inlet port and the outlet port, and has a guide hole for supporting the lifting valve section as movable; as well as A plug, which is fitted into a guide hole in the housing body, forms the load pressure chamber between the plug and the slide valve portion. The supply pressure connection path has: A load pressure port is disposed between the plug and the housing body; The first passage has one end connected to the load pressure port and the other end open in the sliding portion of the plug that slides with the slide valve. as well as The second passage connects the load pressure port to the load pressure chamber. The first passage is positioned to communicate with the throttling passage when the slide valve has moved a predetermined stroke in the opening direction.

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