Pressure compensation valve

Abstract

To provide a pressure compensation valve for improving responsiveness.SOLUTION: In a spool part 220 of a valve element 20, a throttle passage 226 is formed which is normally communicated with a pump port 111. In a case 10, supply pressure communication passages 124, 114, 125 are provided which are closed by the spool part 220 to cut off a space between the throttle passage 226 and a load pressure chamber 221 when a poppet part 210 closes a space between the pump port 111 and a cylinder port 112 with energizing force of a load pressure spring 225, but on the other hand which communicate the throttle passage 226 with the load pressure chamber 221 via a throttle hole 229 when the spool part 220 is moved a predetermined stroke in the opening direction. Between the poppet part 210 and the case 10, a delivery pressure chamber 223 is provided for pressing the poppet part 210 in the closing direction when an internal pressure is increased. To the delivery pressure chamber 223, a delivery pressure passage 213 is connected which is normally communicated with the cylinder port 112.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pressure compensation valve applied to a drive circuit for operating a plurality of fluid pressure actuators.

Background Art

[0002] For example, in a drive circuit that operates a plurality of hydraulic actuators with a single hydraulic pump, a pressure compensation valve is interposed between the hydraulic pump and each hydraulic actuator. As this type of pressure compensation valve, for example, the one described in Patent Document 1 is provided. This pressure compensation valve is configured such that a movable sleeve provided on the outer peripheral portion of the valve body operates appropriately, and the high-pressure side between the pressure of its outlet port (the load pressure of the corresponding hydraulic actuator) and the control pressure from another pressure compensation valve is selected, and the selected high-pressure side pressure is applied as the back pressure of the valve body. According to the drive circuit provided with the pressure compensation valve, it is possible to prevent a situation where oil is supplied only to the hydraulic actuator on the low load pressure side even when the load pressures of the plurality of hydraulic actuators are different from each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when a plurality of hydraulic actuators are operated simultaneously, the load pressure of each hydraulic actuator can change. In this case, in the pressure compensation valve described above, since the back pressure applied to the valve body does not change without the operation of the movable sleeve, it is not necessarily preferable in consideration of the responsiveness of the valve body. In particular, when a suddenly high load pressure occurs with respect to a hydraulic actuator having a low load pressure due to the influence of disturbance or the like, it is difficult to immediately close the valve body, and there is a concern that problems such as a high load pressure being applied to the pressure supply source may occur.

[0005] In view of the above circumstances, an object of the present invention is to provide a pressure compensation valve capable of improving responsiveness.

Means for Solving the Problems

[0006] To achieve the above object, the pressure compensation valve according to the present invention includes a case having an introduction port and a discharge port, a valve body that opens and closes between the introduction port and the discharge port, and a load pressure spring that is interposed between the case and the valve body and biases the valve body in a closing direction. A load pressure chamber is provided between the valve body and the case to press the valve body in a closing direction when the internal pressure increases. The pressure compensation valve controls the supply of fluid from the introduction port to the discharge port based on the supply pressure of the fluid applied to the introduction port and the control pressure applied to the load pressure chamber. The valve body includes a poppet portion that allows the flow of fluid from the introduction port to the discharge port while blocking the flow of fluid from the discharge port to the introduction port, and a spool portion that is slidably disposed in the case with the base end portion facing the load pressure chamber. The tip of the spool portion is maintained in contact with the poppet portion by the biasing force of the load pressure spring. A throttle passage is provided in the spool portion so as to always communicate with the introduction port and open at the sliding portion with the case. In the case, when the poppet portion closes between the introduction port and the discharge port by the biasing force of the load pressure spring, the throttle passage is blocked by the spool portion to cut off the connection between the throttle passage and the load pressure chamber. On the other hand, when the spool portion moves a predetermined stroke in the opening direction, a supply pressure communication passage is provided to connect the throttle passage and the load pressure chamber. A discharge pressure chamber is provided between the poppet portion and the case to press the poppet portion in a closing direction when the internal pressure increases. A discharge pressure passage that always communicates with the discharge port is connected to the discharge pressure chamber, which is characterized in that.

Effect of the Invention

[0007] According to the present invention, since the high-pressure side between the pressure of its own lead-out port and the control pressure from another pressure compensation valve is selected according to the position of the valve body and applied to the load pressure chamber, it is advantageous in terms of the responsiveness of the valve body. Further, when the pressure of the lead-out port suddenly increases with the valve body in the open state, this pressure is applied to the lead-out pressure chamber through the lead-out pressure passage, and only the poppet part moves in the closing direction immediately. Therefore, even when a suddenly high load pressure occurs in a fluid pressure actuator with a low load pressure, there is no risk of problems such as this high load pressure being applied to the pressure supply source.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, a preferred embodiment of the pressure compensation valve according to the present invention will be described in detail with reference to the accompanying drawings.

[0010] Figure 1 shows a hydraulic drive circuit to which a pressure compensation valve according to an embodiment of the present invention is applied. The hydraulic drive circuit illustrated here is for operating two hydraulic cylinder actuators 2A and 2B by a single hydraulic pump 1. The hydraulic pump 1 is a variable displacement type provided with a capacity setting unit 3 that changes the discharge amount according to a given control pressure. The hydraulic cylinder actuators 2A and 2B are double-acting types that operate by selectively supplying oil to the rod chamber 2a and the bottom chamber 2b. A direction switching valve 4 and a pressure compensation valve 5 are provided between the hydraulic pump 1 and the hydraulic cylinder actuators 2A and 2B, respectively. The direction switching valve 4 is interposed between the hydraulic pump 1 and the hydraulic cylinder actuator 2A and between the hydraulic pump 1 and the hydraulic cylinder actuator 2B, respectively, and selectively connects 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 interposed between the direction switching valve 4 and the hydraulic pump 1 and controls the supply of oil to the respective hydraulic cylinder actuators 2A and 2B. Hereinafter, the configuration of the pressure compensation valve 5 will be described in detail, and the characteristic parts of the present invention will also be described. Note that since the configuration of the pressure compensation valve 5 is common to the two hydraulic cylinder actuators 2A and 2B, the one connected to the hydraulic cylinder actuator 2A will be described below.

[0011] Figure 2 shows the specific structure of the pressure compensation valve 5. As shown in the figure, the pressure compensation valve 5 of the present embodiment includes a case 10 and a valve body 20.

[0012] The case 10 includes a case body 110 having a pump port (introduction port) 111 and a cylinder port (discharge port) 112, and a guide hole 113 provided to communicate the pump port 111 and the cylinder port 112, and a plug 120 attached to the guide hole 113 of the case body 110.

[0013] As shown in Fig. 1, the pump port 111 of the case body 110 is connected to the discharge port 1a of the hydraulic pump 1 via the branch supply passage 6. The cylinder port 112 is connected to the input port 4a of the direction switching valve 4 via the supply passage. As shown in Fig. 2, the guide hole 113 is formed so as to communicate from the outer surface of the case body 110 through the cylinder port 112 to the pump port 111. The portion of the guide hole 113 that communicates from the outer surface of the case body 110 to the cylinder port 112 has a substantially constant inner diameter. A tapered valve seat 113a is formed in the portion of the guide hole 113 from the cylinder port 112 to the pump port 111 such that the inner diameter gradually decreases toward the pump port 111. A female screw groove 113b is formed in the portion of the guide hole 113 close to the outer surface of the case body 110.

[0014] The plug 120 has a columnar insertion portion 121 having an outer diameter that fits into the guide hole 113 of the case body 110, and a large-diameter flange portion 122 provided at the base end portion of the insertion portion 121. A male screw 121a is provided on the outer peripheral portion of the insertion portion 121 close to the flange portion 122. The dimension along the axis of the insertion portion 121 is set to be shorter than that of the guide hole 113. This plug 120 is attached to the case body 110 in a state where the flange portion 122 abuts against the outer surface by inserting the tip end portion of the insertion portion 121 into the guide hole 113 and screwing the male screw 121a into the female screw groove 113b of the guide hole 113. As is clear from the figure, the tip end surface of the insertion portion 121 terminates on the front side of the cylinder port 112.

[0015] In the insertion portion 121 of the above-described plug 120, a spool hole 123, a first passage 124, and a second passage 125 are provided. The spool hole 123 is a cavity having a circular cross-section 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 this spool hole 123 is set to be the same as or smaller than the inner diameter of the portion 113c that opens to the pump port 111 in the guide hole 113. The first passage 124 and the second passage 125 are small-diameter holes formed so as to penetrate between the outer peripheral surface of the insertion portion 121 and the inner peripheral surface of the spool hole 123. The first passage 124 extends along the radial direction so as to be substantially perpendicular to the axis of the insertion portion 121 and is formed in a portion of the insertion portion 121 that is on the tip side of the male screw 121a. In the illustrated example, a plurality of first passages 124 are formed radially. The second passage 125 extends while inclining so as to gradually become the base end side toward the center from the outer peripheral surface of the insertion portion 121, and is formed only in the insertion portion 121 such that the opening on the outer peripheral surface is located between the first passage 124 and the male screw 121a. These first passage 124 and second passage 125 communicate with each other via a load pressure port 114 provided in a portion of the case body 110 that is on the tip side of the female screw groove 113b. The load pressure port 114 is an annular cavity formed when the insertion portion 121 of the plug 120 is fitted into the guide hole 113 by providing a recess in the inner peripheral surface of the guide hole 113. As shown in FIG. 1, this load pressure port 114 communicates with the load pressure port 114 of a pressure compensation valve 5 provided in another hydraulic cylinder actuator 2B through a load pressure passage 7. Further, 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 a tank throttle n. Note that the reference numerals R1 and R2 in FIG. 2 are oil seals provided between the guide hole 113 of the case body 110 and the insertion portion 121 of the plug 120, respectively.

[0016] The valve body 20 operates with respect to the case 10 to open and close the space between the pump port 111 and the cylinder port 112. In the present embodiment, the valve body 20 is configured to include a poppet portion 210, a spool portion 220, and a load check spring 230.

[0017] The poppet portion 210 allows the supply of oil from the pump port 111 to the cylinder port 112 while blocking the flow of oil from the cylinder port 112 to the pump port 111. In the present embodiment, a poppet portion 210 having a cylindrical shape with a base end portion fitted into the guide hole 113 and a tapered shape configured to be in surface contact with the valve seat 113a at the tip portion is applied. This poppet portion 210 is slidably fitted into the guide hole 113 via the base end portion and can move along its axis with the guide hole 113 as a guide. That is, the dimension along the axis of the poppet portion 210 is set such that a gap is formed between the tip portion of the plug 120 even when in contact with the valve seat 113a, and it can move to a state separated from the valve seat 113a by moving along the axis of the guide hole 113. The poppet portion 210 is formed with a fitting hole 211, an introduction hole 212, and a derivation pressure passage 213.

[0018] The fitting hole 211 opens only at the base end surface of the portion formed in a columnar shape in the poppet portion 210, has a circular cross-section with a constant inner diameter, and is formed along the axis of the poppet portion 210. The inner diameter of the fitting hole 211 is configured to be smaller than the inner diameter of the spool hole 123 provided in the plug 120. The introduction hole 212 has one end opening at the tip end surface of the poppet portion 210 and the other end opening at the fitting hole 211, and a plurality of them are formed at equal intervals on the circumference centered on the axis of the poppet portion 210. These introduction holes 212 function to always communicate between the pump port 111 and the fitting hole 211 even when the poppet portion 210 is in contact with the valve seat 113a, that is, when the poppet portion 210 closes the space between the cylinder port 112 and the pump port 111. The pressure derivation passage 213 is a groove-shaped notch extending along the axis formed on the outer peripheral surface of the poppet portion 210, and a plurality of them are formed on the outer peripheral surface of the poppet portion 210. These pressure derivation passages 213 function to always communicate between the cylinder port 112 and the space of the portion located on the base end side of the poppet portion 210 in the guide hole 113.

[0019] The spool portion 220 has a columnar shape with a circular cross-section. The base end portion of the spool portion 220 is fitted into the spool hole 123 of the plug 120 to form a load pressure chamber 221 between the spool portion 220. The tip end portion of the spool portion 220 has a smaller diameter than the base end portion and is slidably fitted into the fitting hole 211 of the poppet portion 210. Although not shown in the figure, the gap between the fitting hole 211 and the tip end portion of the spool portion 220 is set to be larger than the gap between the spool hole 123 and the base end portion of the spool portion 220 and also larger than the gap between the guide hole 113 and the poppet portion 210.

[0020] The portion of the spool part 220 that is the most distal end is configured to have an outer diameter smaller than that of the fitting hole 211, and a communication chamber 222 is formed between the poppet part 210. This communication chamber 222 is always in communication with the introduction hole 212 of the poppet part 210 even when the distal end face of the spool part 220 is in contact with the poppet part 210. Also, an annular discharge pressure chamber 223 is formed between the distal end part of the spool part 220 and the guide hole 113 between the plug 120 and the poppet part 210. This discharge pressure chamber 223 is always in a state of being in communication with the cylinder port 112 by the above-described discharge pressure passage 213. The dimension of the spool part 220 along the axis is set shorter than the distance from the fitting hole 211 of the poppet part 210 that is in contact with the valve seat 113a to the base end face of the spool hole 123, and it is possible to move along the axis between these. However, the spool part 220 is pressed by a load pressure spring 225 provided in the load pressure chamber 221, and the distal end face is always maintained in a state of being in contact with the poppet part 210.

[0021] In addition, the spool portion 220 is provided with a throttle passage 226. The throttle passage 226 is configured to include an internal passage 227, an annular passage 228, and a throttle hole 229. The internal passage 227 is linear and formed at the axial center portion of the spool portion 220, and is configured to have a relatively large diameter. While the base end portion of the internal passage 227 is closed, the tip end portion of the internal passage 227 communicates with the communication chamber 222 through a plurality of communication holes 227a along the radial direction. The annular passage 228 is annular and provided at a portion of the outer peripheral surface of the spool portion 220 that is fitted into the spool hole 123 of the plug 120, and is formed between the spool portion 220 and the plug 120. This annular passage 228 is formed at a position on the tip end portion side of the first passage 124 provided in the plug 120 when the poppet portion 210 abuts against the valve seat 113a and the tip end surface of the spool portion 220 abuts against the poppet portion 210. When the spool portion 220 moves toward the base end side from this state, before the base end portion of the spool portion 220 abuts against the plug 120, the annular passage 228 faces the first passage 124 and can communicate with each other. The throttle hole 229 has an inner diameter smaller than that of the internal passage 227 and larger than that of the tank throttle n, and is the only one formed in the spool portion 220 in a state of communicating between the annular passage 228 and the internal passage 227. Reference numeral R3 in the figure is a seal unit provided between the spool portion 220 and the plug 120, and reference numeral R4 is a seal unit provided between the spool portion 220 and the poppet portion 210. As these seal units R3 and R4, for example, a combination of an O-ring and a ring made of PTFE (polytetrafluoroethylene) can be applied.

[0022] The load check spring 230 is interposed between the poppet portion 210 and the spool portion 220 in the derivation pressure chamber 223 to prevent the poppet portion 210 from moving inadvertently when the cylinder port 112 becomes negative pressure or when vibration is applied to the case body 110. In the present embodiment, a load check spring 230 having a set load smaller than that of the load pressure spring 225 is applied.

[0023] In the pressure compensation valve 5 configured as described above, as shown in FIG. 2, even when the pump port 111 is closed by the poppet portion 210, the space between the throttle passage 226 and the pump port 111 is in a state of being communicated with each other through the introduction hole 212, the communication chamber 222, and the communication hole 227a. However, in this state, since the throttle hole 229 is blocked by the insertion portion 121, the load pressure chamber 221 and the throttle passage 226 are blocked from each other. As a result, as shown in FIG. 1, 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. That is, in the state shown in FIG. 2, as the force for operating the valve body 20 in the closing direction, only the biasing force of the load pressure spring 225 acts, and the valve body 20 moves in the opening direction without resisting the pressure in the load pressure chamber 221. Therefore, even considering the influence of the flow force acting due to the fluid flow when the poppet portion 210 starts to open, at a stage where the supply pressure of the pump port 111 is low, as shown in FIG. 3, the valve body 20 can be moved in the opening direction, and it becomes possible to reduce the horsepower loss of the hydraulic pump 1.

[0024] When the movement of the valve body 20 in the opening direction progresses from the state shown in FIG. 3 and the annular passage 228 reaches a position facing the first passage 124 as shown in FIG. 4, the throttle passage 226 communicates with the load pressure chamber 221 through the first passage 124, the load pressure port 114, and the second passage 125. As described above, the throttle passage 226 is communicated with the pump port 111 through the communication hole 227a, the communication chamber 222, and the introduction hole 212. Therefore, in the state shown in FIG. 4, the supply pressure of the pump port 111 is applied to the load pressure chamber 221, and the biasing force due to the pressure in this load pressure chamber 221 and the biasing force of the load pressure spring 225 act on the valve body 20 in the closing direction. As a result, the valve body 20 operates appropriately based on the balance between the biasing force due to the supply pressure of the pump port 111 (the load pressure of the hydraulic cylinder actuator 2A), the biasing force due to the pressure in the load pressure chamber 221, and the biasing force of the load pressure spring 225, and the flow rate of the oil supplied to the hydraulic cylinder actuator 2A is controlled.

[0025] Here, in the hydraulic drive circuit shown in FIG. 1, the load pressure ports 114 of the two pressure compensation valves 5 communicate with each other through the load pressure passage 7. Therefore, when the hydraulic cylinder actuators 2A and 2B are operating in a compound manner, the high-pressure supply pressure (load pressure) is applied to the load pressure chambers 221 of the two pressure compensation valves 5. That is, in the pressure compensation valve 5 on the low-pressure side of the supply pressure, the valve body 20 moves in the closing direction by the high-pressure supply pressure applied to the load pressure chamber 221 through the load pressure port 114 and the second passage 125. Along with this, the space between the load pressure chamber 221 and the throttle passage 226 is blocked. Therefore, even when the load pressures of the plurality of hydraulic cylinder actuators 2A and 2B are different from each other, it is possible to prevent a situation where oil is supplied only to the hydraulic cylinder actuator on the low load pressure side. Moreover, since the supply pressure is applied to the load pressure chamber 221 through the load pressure port 114 and the second passage 125 and no operating member is required in the middle, it is also advantageous in terms of responsiveness.

[0026] Furthermore, when the hydraulic cylinder actuators 2A and 2B are operating in a compound manner and the load pressure is reversed due to the influence of disturbances or the like, that is, when the load pressure of the hydraulic cylinder actuator on the low load pressure side suddenly increases, the pressure of the high-pressure cylinder port 112 is applied to the derived pressure chamber 223 through the derived pressure passage 213. As a result, the poppet part 210 immediately moves in the closing direction, and the space between the cylinder port 112 and the pump port 111 is blocked, so that a situation where a high load pressure is applied to the hydraulic pump 1 can be prevented.

[0027] In the above-described embodiment, the load check spring 230 is interposed between the poppet part 210 and the spool part 220, but it is not always necessary to provide the load check spring 230. Also, although the derived pressure passage 213 is illustrated as being provided only in the poppet part 210, the derived pressure passage may be provided in the case body 110 so that the cylinder port 112 and the derived pressure chamber 223 are always in communication, or the derived pressure passage may be provided in both the poppet part 210 and the case body 110.

Description of Symbols

[0028] 5 Pressure compensation valve 10 Case 20 Valve body 110 Case body 111 Pump port 112 Cylinder port 113 Guide hole 114 Load pressure port 120 Plug 124 First passage 125 Second passage 210 Poppet part 213 Derived pressure passage 220 Spool part 221 Load pressure chamber 223 Derived pressure chamber 225 Load pressure spring 226 Throttle passage 227 Internal passage 228 Annular passage 229 Throttle hole

Claims

1. A pressure compensating valve having a case with 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 interposed between the case and the valve body for biasing the valve body in a closing direction. A load pressure chamber is provided between the valve body and the case for pressing the valve body in a closing direction when the internal pressure increases. The pressure compensating valve controls the supply of fluid 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, wherein the valve body includes a poppet portion that allows fluid to flow from the inlet port to the outlet port while blocking fluid flow from the outlet port to the inlet port, and a spool portion slidably disposed in the case with its base end facing the load pressure chamber. The tip of the spool portion is maintained in contact with the poppet portion by the biasing force of the load pressure spring, a throttle passage is provided in the spool portion that is always in communication with the inlet port and opens at the sliding portion with the case, in the case, when the poppet portion closes between the inlet port and the outlet port by the biasing force of the load pressure spring, the spool portion blocks the throttle passage from communicating with the load pressure chamber. On the other hand, when the spool portion moves a predetermined stroke in the opening direction, a supply pressure communication passage is provided to communicate the throttle passage with the load pressure chamber, a discharge pressure chamber is provided between the poppet portion and the case for pressing the poppet portion in a closing direction when the internal pressure increases. A discharge pressure passage that is always in communication with the outlet port is connected to the discharge pressure chamber. The pressure compensating valve is characterized by this.

2. The case includes a case body having the inlet port and the outlet port and a guide hole for movably supporting the poppet portion, and a plug mounted in the guide hole of the case body and forming the load pressure chamber between the plug and the spool portion, the supply pressure communication passage includes a load pressure port provided between the plug and the case body, a first passage having one end communicating with the load pressure port and the other end opening at the sliding portion with the spool portion in the plug, and a second passage communicating between the load pressure port and the load pressure chamber. The pressure compensation valve according to claim 1, wherein the first passage is provided at a position where it communicates with the throttle passage when the spool portion moves a predetermined stroke in the opening direction.

Images