valve

Abstract

Provided is a valve in which a spool smoothly operates.　This valve 1 comprises: a housing 2; a spool 3 which has a throttle port 34a, is disposed in the housing in an axially movable manner, and partitions the housing 2 into a first chamber S1 and a second chamber S2; and a biasing means 4 for biasing the spool 3 toward the first chamber S1 side in the axial direction, wherein the spool 3 operates in the axial direction due to a pressure difference between the first chamber S1 and the second chamber S2, and the biasing means 4 is disposed further toward the first chamber S1 side or the second chamber side S2 than the throttle port 34a.

Description

[Technical Field]

[0001] The present invention relates to a valve, for example, a valve that controls the flow rate of a fluid flowing between a primary chamber and a secondary chamber. [Background technology]

[0002] Valves, used to control working fluids in various industrial fields, consist of a valve seat and a valve body that can move toward and away from the valve seat. By adjusting the valve opening, the pressure and flow rate of the working fluid can be controlled. Among such valves, spool valves are known, in which a spool moves parallel to the opening of the valve seat.

[0003] The spool valve described in Patent Document 1 comprises a valve body, a cylindrical spool, a check spring, and a pressure compensation spring. The cylindrical spool is axially movable within the valve body. The cylindrical spool also has a partition wall, which divides the spool into a check spring chamber and a pressure compensation spring chamber on both sides of the axial direction. A check spring is placed in the check spring chamber, and a pressure compensation spring is placed in the pressure compensation spring chamber, and the cylindrical spool is balanced in a neutral position.

[0004] Furthermore, the valve body is provided with a first flow path extending from the first port and connecting a check spring chamber and a flow rate setting throttle valve, a second flow path connecting a pressure compensation spring chamber and a second port, and a third flow path connecting the throttle valve and the pressure compensation spring chamber. The cylindrical spool is provided with an inlet / outlet hole corresponding to the third flow path and a throttle hole corresponding to the second flow path.

[0005] When fluid flows from the first port into the first flow path, the fluid flows out to the second port through the throttle valve, third flow path, inlet / outlet hole, pressure compensation spring chamber, throttle hole, and second flow path. At this time, the cylindrical spool moves axially according to the pressure difference between the check spring chamber and the pressure compensation spring chamber, adjusting the opening of the throttle hole. This makes it possible to maintain a constant flow rate to the second port even if there are fluctuations in the pressure difference between the check spring chamber and the pressure compensation spring chamber.

[0006] On the other hand, when fluid flows from the second port into the second flow path, the cylindrical spool moves towards the check spring chamber, and the inlet / outlet hole and the check spring chamber are directly connected. As a result, the fluid flows out to the first port through the second flow path, the throttling hole, the pressure compensation spring chamber, the inlet / outlet hole, and the check spring chamber. At this time, the inlet / outlet hole is fully open and in communication with the check spring chamber, so the flow rate to the first port is not restricted. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Microfilm of Utility Model Application No. 62-25137 (Utility Model Application No. 4-7415) (Page 2, Figure 1) [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in a spool valve like the one described in Patent Document 1, the pressure compensation spring is positioned so as to cross the inlet / outlet hole and throttling hole, which are provided radially through the cylindrical spool. This raises concerns that the fluid flow entering and exiting the inlet / outlet hole and throttling hole may be obstructed by the pressure compensation spring, or that the pressure compensation spring may be deformed in the bending direction due to the fluid flow.

[0009] This invention was made in view of these problems, and aims to provide a valve in which the spool operates smoothly. [Means for solving the problem]

[0010] To solve the above problems, the valve of the present invention is: The device comprises a housing, a spool having an aperture port and positioned axially movable within the housing to separate a primary chamber and a secondary chamber of the housing, and a biasing means for biasing the spool axially toward the primary chamber. The spool is a valve that moves axially due to the pressure difference between the primary chamber and the secondary chamber, The biasing means is located on the primary chamber side or the secondary chamber side of the aperture port. This prevents the fluid flow out of the spool's throttling port from being obstructed by the biasing mechanism. Furthermore, it prevents the biasing mechanism from deforming radially due to the fluid flowing out of the spool's throttling port. Therefore, there is no need to select the biasing mechanism based on fluid requirements, and the biasing mechanism can be freely designed.

[0011] The spool may have a stepped portion formed thereon, which contacts the end of the biasing means. According to this, a portion of the biasing mechanism can be superimposed on the spool in the axial direction, which ensures that the flow of fluid out of the throttle port is not obstructed by the biasing mechanism, and also shortens the axial dimension of the valve.

[0012] The stepped portion may be provided on the inner circumferential surface of the spool. According to this, since the biasing mechanism can be placed inside the spool, a large outer surface area of ​​the spool guided by the inner surface of the housing can be secured.

[0013] The spool is further provided with an on / off port for switching the communication state between the primary chamber and the secondary chamber. The biasing means may be located on the secondary chamber side of the opening / closing port. This design avoids interference between the fluid flowing through the opening / closing port and the biasing mechanism. The flow rate adjustment mechanism and the opening / closing mechanism can be integrated and compactly constructed using a single spool.

[0014] The spool has a primary chamber biasing means that biases it axially toward the secondary chamber side, The throttling port and the primary chamber may be connected by a flow path that bypasses the primary chamber-side biasing member. According to this, it is possible to avoid interference between the fluid flowing between the throttle port and the primary chamber and the primary chamber side biasing means.

Brief Description of the Drawings

[0015] [Figure 1] It is a longitudinal sectional view showing the valve in Embodiment 1 of the present invention. [Figure 2] It is a diagram showing the valve with hydraulic symbols. [Figure 3] It is a longitudinal sectional view showing the state of the valve in the control flow rate flow. [Figure 4] It is an enlarged schematic view showing the displacement amount X. [Figure 5] It is a graph showing the relationship between the differential pressure before and after and the flow rate. [Figure 6] It is a longitudinal sectional view showing the state of the valve in the free flow rate flow. [Figure 7] It is a longitudinal sectional view showing the valve in Embodiment 2 of the present invention.

Mode for Carrying Out the Invention

[0016] A mode for carrying out the valve according to the present invention will be described below based on examples. In addition, the examples will be described by taking a flow control valve as an example.

Examples

[0017] The flow control valve according to Embodiment 1 will be described with reference to FIGS. 1 to 6. Hereinafter, the left side of the paper surface of FIG. 1 will be described as the left side of the flow control valve, and the right side of the paper surface of FIG. 1 will be described as the right side of the flow control valve. Further, the left side of the flow control valve will be described as the primary chamber side, and the right side of the flow control valve will be described as the secondary chamber side.

[0018] As shown in FIG. 1, the flow control valve 1 is a spool type flow control valve and is incorporated in a hydraulic circuit. In addition, the flow control valve 1 is used by being attached to the mounting hole of the valve housing on the device side.

[0019] The flow control valve 1 mainly consists of a housing 2, a flow control spool 3 (hereinafter simply referred to as spool 3), a flow control spring 4 as a biasing member, a check spring 5 as a primary chamber side biasing member, and a plug 6.

[0020] Housing 2 is composed of a first cylindrical member 21 and a second cylindrical member 22.

[0021] The first cylindrical member 21 has a through hole 21a that penetrates in the axial direction, and an annular projection 21b that protrudes in an annular shape toward the inner diameter at approximately the axial center. Specifically, a recess 21c that opens to the left is provided to the left of the annular projection 21b of the first cylindrical member 21, and a recess 21d that opens to the right is provided to the right of the annular projection 21b.

[0022] The second cylindrical member 22 is sealed to the left side of the first cylindrical member 21 by screwing, and the plug 6 is sealed to the right side by screwing.

[0023] The second cylindrical member 22 has a small diameter portion 22a, a large diameter portion 22b, and a threaded portion 22c.

[0024] The small-diameter portion 22a has a smaller diameter than the through-hole 21a of the first cylindrical member 21 and is inserted into the through-hole 21a from the left side.

[0025] Furthermore, the large-diameter portion 22b has a larger diameter than the through-hole 21a, and by contacting the left end face 21e of the first cylindrical member 21, the second cylindrical member 22 is positioned in the insertion direction.

[0026] The threaded portion 22c is designed to be screwed into a female threaded portion provided on the inner circumferential surface of the first cylindrical member 21.

[0027] More specifically, the second cylindrical member 22 has an O-ring 7 positioned at the corner formed by the large-diameter portion 22b and the threaded portion 22c, and the O-ring 7 seals the gap between the first cylindrical member 21 and the second cylindrical member 22. The plug 6 also has an O-ring 10 positioned at the corner formed by the large-diameter portion 6b and the threaded portion 6c, and the O-ring 10 seals the gap between the first cylindrical member 21 and the plug 6. Furthermore, the second cylindrical member 22 has an O-ring 8 positioned in an annular groove formed at the right end of the small-diameter portion 22a that is open in the outward direction, and the O-ring 8 seals the space between the outer circumferential surface of the right end of the small-diameter portion 22a and the inner circumferential surface of the annular protrusion 21b.

[0028] An annular space 23 is formed between the outer circumferential surface of the small-diameter portion 22a, which is sandwiched between the O-rings 7 and 8, and the inner circumferential surface of the first cylindrical member 21.

[0029] Between the small-diameter portion 22a and the threaded portion 22c, a partition wall 22d is formed that divides the internal space of the second cylindrical member 22 on both axial sides. A through hole 22j is formed in the center of the partition wall 22d, penetrating in the axial direction.

[0030] A primary chamber S1 is formed inside the portion of the second cylindrical member 22 to the left of the partition wall 22d. The primary chamber S1 is in communication with the primary side inlet 22h, which opens on the left side of the second cylindrical member 22.

[0031] Furthermore, multiple communication holes 22e are formed circumferentially near the outer diameter side of the partition wall 22d in the second cylindrical member 22, connecting the space 23 and the primary chamber S1. The space 23 and the communication holes 22e constitute a flow path that connects the throttling port 34a (described later) and the primary chamber S1.

[0032] Furthermore, the small-diameter portion 22a is provided with a first annular groove 22f and an orifice 221, and a second annular groove 22g and a hole 222.

[0033] The first annular groove 22f and the second annular groove 22g are grooves that open to the inner diameter side of the small diameter portion 22a and are spaced apart in the axial direction.

[0034] The orifice 221 is provided to connect the first annular groove 22f on the right side with the space 23.

[0035] The hole 222 is provided so as to connect the second annular groove 22g on the left side with the space 23.

[0036] The spool 3 is positioned to slide axially inside the small-diameter portion 22a.

[0037] The spool 3 is a cylindrical body, and a partition wall 31 is formed on the left side of the spool 3, dividing its internal space into axial sections on both sides.

[0038] The spool 3 has a recess 32 that opens to the left, formed by the cylindrical portion 3A to the left of the partition wall 31 and the partition wall 31, and a recess 33 that opens to the right, formed by the cylindrical portion 3B to the right of the partition wall 31 and the partition wall 31.

[0039] A check spring chamber 9, where the check spring 5 (described later) is located, is formed by the recess 32 of the spool 3 and the recess formed by the small-diameter portion 22a and partition wall 22d of the second cylindrical member 22. The check spring chamber 9 is in communication with the primary chamber S1 through the through hole 22j.

[0040] Part 3B has a thickened section 34 on the left side and a thinned section 35 on the right side. The outer surfaces of the thickened section 34 and the thinned section 35 are flat and continuous. The inner surface of the thickened section 34 is located on the inner diameter side than the inner surface of the thinned section 35. The right end of the thickened section 34 is a stepped section 36 that protrudes on the inner diameter side than the thinned section 35.

[0041] Multiple diaphragm ports 34a and multiple opening / closing ports 34b are provided in the circumferential direction on the thickened portion 34.

[0042] Furthermore, the recess 33 of the spool 3 and the recess 21d of the first cylindrical member 21 constitute a secondary chamber S2. The secondary chamber S2 is in communication with the secondary side outlet inlet 6a, which is provided through the plug 6.

[0043] Referring to Figure 2, the throttling port 34a of the spool 3, the first annular groove 22f and orifice 221 of the second cylindrical member 22 constitute the flow rate adjustment mechanism V1. In addition, the opening / closing port 34b of the spool 3, the second annular groove 22g and hole 222 of the second cylindrical member 22 constitute the opening / closing mechanism V2.

[0044] Returning to Figure 1, the flow control spring 4 is a coil spring and is positioned between the stepped portion 36 of the spool 3 and the plug 6. That is, the flow control spring 4 biases the spool 3 toward the left.

[0045] The check spring 5 is a coil spring and is positioned between the check spring chamber 9, in other words, between the partition wall 31 of the spool 3 and the partition wall 22d of the second cylindrical member 22. That is, the check spring 5 biases the spool 3 toward the right.

[0046] When no oil is flowing through the flow control valve 1, the spool 3 is positioned in the neutral position by the biasing force of the flow control spring 4 and the check spring 5 (see Figure 1). In the neutral position of the spool 3, the throttling port 34a is fully open and in communication with the first annular groove 22f, and the opening / closing port 34b is not in communication with the second annular groove 22g. The flow control spring 4 and the check spring 5 are balanced by a biasing force F1.

[0047] Next, the operation of the flow control valve 1 will be explained.

[0048] First, the operation of the flow control valve 1 in a controlled flow rate where oil flows in from the primary inlet 22h and flows out to the secondary outlet 6a will be explained using Figure 3.

[0049] Oil flowing in from the primary inlet 22h flows out to the secondary outlet 6a through the primary chamber S1, the communication hole 22e, the space 23, the orifice 221, the first annular groove 22f, the throttling port 34a, and the secondary chamber S2.

[0050] At this time, the pressure in the primary chamber S1 is slightly higher than the pressure in the secondary chamber S2, and the spool 3 is in equilibrium in the state shown in Figure 4, which is a displacement of X to the right from the state where no oil is flowing. At this time, the opening / closing port 34b is closed by the small diameter portion 22a of the second cylindrical member 22. Also, in Figure 4, the throttling port 34a in the state where no oil is flowing is shown with a dashed line. Of the two dashed lines indicating the displacement X, the left one is the meridian passing through the center of the throttling port 34a in the state where no oil is flowing, and the right one is the meridian passing through the center of the throttling port 34a after the spool 3 has been displaced to the right.

[0051] Here, let S be the cross-sectional area of ​​spool 3, K1 be the spring constant of flow control spring 4, and K2 be the spring constant of check spring 5. Also, if Q is the flow rate through orifice 221, M is the cross-sectional area of ​​orifice 221, P1 is the pressure before inflow into orifice 221, and P2 is the pressure after inflow, then equation (1) below holds true from the orifice equation. Q = C·M·√(P1-P2), where C is a constant. (1)

[0052] Furthermore, if the opening area of ​​the throttling port 34a is N and the pressure in the secondary chamber S2 is P3, then equation (2) below holds, similar to equation (1). Q = C·N·√(P2-P3), where C is a constant. (2)

[0053] Therefore, from equations (1) and (2), equation (3) below can be derived. Q = C·(M·N / √(M) 2 +N 2 ))·√(P1-P3) (3)

[0054] Furthermore, it is assumed that the force equilibrium equation (4) below holds true in the axial direction of spool 3. P1·S+(F1-K2·X)=P3·S+(F1+K1·X) ∴ P1-P3=(K1+K2)·X / S (4)

[0055] If, from this state, a flow rate Qe exceeding the flow rate Q flows through the orifice 221, the value of the differential pressure (P1-P3) in equation (3) will also increase. However, as the value of the differential pressure (P1-P3) in equation (4) increases, the value of the displacement X will also increase.

[0056] As shown in Figure 4, as the displacement X increases, the opening area N of the throttling port 34a decreases. As a result, from equation (3), (M·N / √(M 2 +N 2 As the value of )) decreases, the oil flow is restricted, causing the flow rate Qe to decrease, and ultimately the flow rate balances out at a point where the value of Q and the differential pressure (P1-P3) across the orifice 221 and the restricting port 34a remain constant.

[0057] In other words, if a flow rate exceeding the flow rate Q attempts to pass through the orifice 221, the spool 3 activates to prevent the flow from exceeding a certain flow rate Q.

[0058] Therefore, if we represent this on a graph, Q1 represents a certain constant flow rate, and P1-P3 represents a constant differential pressure. X This results in Figure 5.

[0059] Next, the operation of the flow control valve 1 in a free flow scenario where oil flows in from the secondary outlet 6a and out to the primary outlet 22h will be explained using Figure 6.

[0060] Oil flowing in from the secondary outlet 6a branches off from the secondary chamber S2 to the on / off port 34b or the throttling port 34a. Oil flowing into the on / off port 34b flows into space 23 through the flow paths of the second annular groove 22g and hole 222. Oil flowing into the throttling port 34a flows into space 23 through the flow paths of the first annular groove 22f and orifice 221. Oil flowing into space 23 flows out to the primary outlet 22h through the communication hole 22e and primary chamber S1.

[0061] Let the flow rate of the oil flowing into the secondary side inlet / outlet 6a be Q’, the pressure in the secondary chamber S2 be P1’, and the pressure in the primary chamber S1 be P3’. The spool 3 is in balance when it is displaced by a displacement amount Y to the left from the state where no oil is flowing. At this time, the following force balance equation (5) holds in the axial direction of the spool 3. P1’·S+(F1-K1·Y)=P3’·S+(F1+K2·Y) ∴ P1’-P3’=(K1+K2)·Y / S (5)

[0062] Also, let the flow rate flowing through the throttle port 34a be Q1’, the flow rate flowing through the on-off port 34b be Q2’, the cross-sectional area of the orifice 221 be M, the opening area of the throttle port 34a be N, and the opening area of the on-off port 34b be R. Then, the following equations (6) to (8) hold from the orifice formula. Q1’=C·(M·N / √(M 2 +N 2 ))·√(P1’-P3’) where C: constant (6) Q2’=C·R·√(P1’-P3’) where C: constant (7) Q’=Q1’+Q2’ (8)

[0063] Therefore, from equations (6) to (8), the following equation (9) is derived. Q’=C·((M·N / √(M 2 +N 2 ))+R)·√(P1’-P3’) (9)

[0064] Considering the case where a flow rate Qe’ exceeding the flow rate Q’ flows in from the secondary side inlet / outlet 6a from this state. When the flow rate Qe’ flows in, the differential pressure (P1’-P3’) in the above equation (9) increases, and when the value of the differential pressure (P1’-P3’) in equation (5) increases, the value of the displacement Y also increases. However, unlike the controlled flow described above, the opening areas of the throttle port 34a and the on-off port 34b in the spool 3 are not restricted.

[0065] As explained above, the flow control spring 4 is positioned on the secondary chamber S2 side of the throttling port 34a. This arrangement prevents the flow control spring 4 from being obstructed by the flow control spring 4 when oil enters and exits the throttling port 34a, as the flow control spring 4 is positioned axially to the right of the throttling port 34a. Furthermore, it prevents the flow control spring 4 from being deformed radially by the flow of oil entering and exiting the throttling port 34a.

[0066] Therefore, it is not necessary to consider the number of turns or wire diameter of the flow control spring 4 based on the oil requirements, and the flow control spring 4 can be freely designed.

[0067] Furthermore, the spool 3 has a stepped portion 36 that contacts the end of the flow control spring 4. This allows the flow control spring 4 to be positioned so as to overlap axially with the inner diameter end of the throttling port 34a. In other words, the flow control spring 4 can be positioned on the outer diameter side of the inner circumferential surface of the thickened portion 34 through which the throttling port 34a opens. This ensures that the flow of fluid flowing out of the throttling port 34a is not obstructed by the flow control spring 4. In addition, since a portion of the flow control spring 4 can be radially overlapped with the spool 3, the axial dimension of the flow control valve 1 can be shortened. Furthermore, misalignment of the axes between the spool 3 and the flow control spring 4 can be suppressed.

[0068] Furthermore, the stepped portion 36 is provided on the inner circumferential surface of the spool 3, allowing the flow control spring 4 to be placed inside the spool 3. This makes it possible to secure a large axial area for the outer circumferential surface of the spool 3 guided by the inner circumferential surface of the small-diameter portion 22a of the second cylindrical member 22, thereby stabilizing the axial movement of the spool 3.

[0069] Furthermore, the spool 3 is provided with an on / off port 34b that switches the communication state with the primary chamber S1, and the flow rate control spring 4 is positioned on the secondary chamber S2 side of the on / off port 34b. This prevents interference between the oil flowing through the on / off port 34b and the 34b itself.

[0070] Furthermore, in the case of a flow control valve 1, a single spool 3 can be used to compactly integrate a flow adjustment mechanism V1 using a throttle port 34a and an opening / closing mechanism V2 using an opening / closing port 34b.

[0071] Furthermore, since the flow control valve 1 is equipped with a check spring 5 that biases the spool 3 axially toward the secondary chamber S2, the axial movement of the spool 3 is stabilized, and the flow adjustment mechanism V1 and the opening / closing mechanism V2 can function accurately.

[0072] Furthermore, the aperture port 34a and the primary chamber S1 are connected by a space 23 that bypasses the check spring 5 and a communication hole 22e. This prevents interference between the oil flowing between the aperture port 34a and the primary chamber S1 and the check spring 5.

[0073] Furthermore, the housing 2 is composed of a first cylindrical member 21 and a second cylindrical member 22, with a space 23 formed between the first cylindrical member 21 and the second cylindrical member 22. By combining the first cylindrical member 21 and the second cylindrical member 22 in this way, a space 23 connecting the aperture port 34a and the primary chamber S1 can be easily formed. [Examples]

[0074] Next, the valve according to Embodiment 2 will be described with reference to Figure 7. Note that descriptions of components that are identical to those in the previous embodiment and therefore redundant will be omitted.

[0075] As shown in Figure 7, the flow control valve 10 of this embodiment 2 is configured such that a cylindrical member 12, a spool 13, a flow control spring 14, and a check spring 15 are directly incorporated into a valve body 40, such as a main control valve.

[0076] The cylindrical member 12 is sealed by screwing into the mounting hole 40a of the valve body 40.

[0077] An annular space 123 is formed between the small-diameter portion 12a of the cylindrical member 12 and the inner circumferential surface of the mounting hole 40a of the valve body 40.

[0078] Furthermore, the recess 133 of the spool 13 and the mounting hole 40a of the valve body 40 constitute a secondary chamber S2'. The secondary chamber S2' is in communication with the secondary outlet inlet 40b provided in the valve body 40.

[0079] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0080] For example, in the above embodiments 1 and 2, a configuration in which the spool is biased from both axial sides by a flow control spring and a check spring was illustrated, but the invention is not limited to this, and it is sufficient to have a flow control spring, which is a biasing means that biases the spool axially toward the primary chamber side. In other words, the check spring configuration may be omitted.

[0081] Furthermore, while embodiments 1 and 2 described above illustrate a configuration in which a stepped portion is provided on the inner circumferential surface of the spool and the end of the flow control spring abuts against the stepped portion, the stepped portion may also be provided on the outer circumferential surface of the spool and the flow control spring may be fitted onto the spool.

[0082] Furthermore, while embodiments 1 and 2 described above illustrate a configuration in which an opening / closing port is provided on the primary chamber side of the spool and an aperture port is provided on the secondary chamber side of the opening / closing port, the aperture port may also be provided on the primary chamber side of the spool and an opening / closing port may be provided on the secondary chamber side of the aperture port.

[0083] Furthermore, in the above embodiments 1 and 2, the flow path connecting the aperture port and the primary chamber was provided to bypass the check spring, but the flow path may also be provided to cross the check spring.

[0084] Furthermore, although the flow control spring and check spring are exemplified as compression springs, they may also be tension springs. In this case, the flow control spring may be located on the primary chamber side of the aperture port, and the check spring on the secondary chamber side of the aperture port. Also, the biasing means is not limited to springs, but may be an elastic body such as synthetic resin, a spring mechanism such as an air spring, etc.

[0085] Furthermore, while Examples 1 and 2 above illustrate the use of oil as the fluid, other liquids, gases, or gas-liquid mixtures may also be used.

[0086] Furthermore, while embodiments 1 and 2 above illustrate a configuration in which an on / off port is provided on the spool, an on / off port is not required, and a valve that only controls the controlled flow rate may also be used.

[0087] Furthermore, while the first embodiment described above illustrates a configuration in which the orifice is provided in the small-diameter portion of the second cylindrical member, the position of the orifice can be freely determined, and the orifice may not be provided at all. [Explanation of symbols]

[0088] 1. Flow control valve (valve) 2 Housing 3. Flow control spool 4. Flow control spring (biasing means) 5. Check spring (primary chamber biasing means) 10 Flow control valve (valve) 13 Spools 14 Flow control spring 15 Check Spring 21 First cylindrical member 22 Second cylindrical member 22e Communication hole (flow channel) 23 Space (flow channel) 34a Aperture port 34b Open / Close Port 36 Step section 40 Valve body 221 Orifice 222 holes S1 Primary Chamber S2,S2' Secondary Chamber V1 Traffic Control Agency V2 Opening and Closing Mechanism

Claims

1. The device comprises a housing, a spool having an aperture port and positioned axially movable within the housing to separate a primary chamber and a secondary chamber of the housing, and a biasing means for biasing the spool axially toward the primary chamber. The spool is a valve that moves axially due to the pressure difference between the primary chamber and the secondary chamber, The biasing means is located on the primary chamber side or the secondary chamber side of the aperture port. The spool has a primary chamber biasing means that biases it axially toward the secondary chamber side, The valve is connected to the throttle port and the primary chamber by a flow path that bypasses the primary chamber-side biasing means.

2. The valve according to claim 1, wherein the spool has a stepped portion formed thereon, which contacts the end of the biasing means.

3. The valve according to claim 2, wherein the stepped portion is provided on the inner circumferential surface of the spool.

4. The spool is further provided with an on / off port for switching the communication state between the primary chamber and the secondary chamber. The valve according to claim 1, wherein the biasing means is located on the secondary chamber side of the opening / closing port.

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