JP2004251384A - Check valve and power steering device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a check valve capable of preventing deterioration in original functions of a check valve due to deformation of a movable plug, and of easily changing leak pressure when preventing backflow. <P>SOLUTION: The check valve is equipped with a cylindrical valve housing 23 having a supply port 21 and discharge port 22 of a fluid, a valve seat 24 provided to the valve housing 23, a movable plug 25 accommodated on the discharge port 22 side of the valve seat 24 in the valve housing 23 so as to be freely attachable to and detachable from the valve seat 24, and elastic member 26 brought into intimate contact with the valve seat 24 by biasing the movable plug 25 to the supply port 21 side. The valve seat 24 is constituted by a movable ring accommodated in the valve housing 23 so as to be freely movable in the coaxial state with the valve housing 21 and in the axial direction. In addition, the valve housing 23 is provided inside an abutting part 39 for determining a moving limit to the discharge port 22 side of the movable ring by abutment of the outer peripheral edge of the movable ring and a second elastic member 41 for bringing the outer peripheral edge of the ring into intimate contact with the abutting part 39 by biasing the movable ring to the discharge port 22 side. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a check valve and a power steering device used for steering a vehicle using the check valve.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a power steering device (power steering) that assists a steering force by hydraulic pressure has been used as a steering device (steering) for a vehicle. This power steering device outputs a steering assist force by supplying pressure oil discharged from a hydraulic pump to a hydraulic cylinder or the like. Between the hydraulic pump and the hydraulic cylinder, there is provided a hydraulic control valve for controlling the supply of pressure oil to the hydraulic cylinder according to the steering direction and the steering resistance. A check valve is built in the input port portion from the hydraulic pump to the hydraulic control valve to prevent backflow from the hydraulic control valve to the hydraulic pump.
[0003]
In the above-described power steering device, when a car is traveling on a rough road or when a wheel rides on a curb, the hydraulic oil supplied to the hydraulic cylinder by the impact applied to the wheel is supplied to the hydraulic pump side. Trying to flow backwards. However, since the check valve provided at the input port portion of the hydraulic control valve prevents the backflow, the so-called kickback phenomenon in which the handle is removed by the backflow of the pressure oil is prevented.
[0004]
However, if the reverse flow of pressure oil is completely prevented by the check valve, the internal pressure of the hydraulic cylinder will rise excessively, and an excessive load will be applied to the ball joint and the like provided between the hydraulic cylinder and the wheels. There is a concern that this will have an adverse effect. Therefore, conventionally, a round hole-shaped orifice is formed at the center of the movable plug (see FIG. 4 of Patent Document 1), or a plurality of leak grooves are radially formed on the sealing surface of the movable plug (see FIG. 4). Also, in the case where the backflow of the pressure oil is prevented by the check valve, a small amount of the pressure oil is caused to leak to the hydraulic pump side (see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-11-49004 (Claims 1 to 4, FIGS. 1 to 4)
[0006]
[Problems to be solved by the invention]
However, the check valve used in the conventional power steering apparatus described above avoids excessive pressurization in the hydraulic cylinder only by allowing pressure oil to escape from an orifice or a leak groove formed directly on the movable plug. Therefore, when the load of high oil pressure is repeated, the movable plug itself is gradually deformed, and the original function as the check valve may be impaired, and the effect of preventing the kickback phenomenon may be reduced.
In addition, as in the prior art, in the means for forming an orifice or a leak groove in the movable plug, the outer diameter of the orifice may be slightly reduced in order to change the leak pressure at the time of backflow prevention in response to a model change of the power steering device. Or the number of leak grooves, the groove width, etc., need to be finely changed. In this respect, there is a disadvantage that the operation of changing the leak pressure is very complicated.
[0007]
The present invention has been made in view of the above-described circumstances, and a check valve that can prevent a reduction in an original function as a check valve due to deformation of a movable stopper and that can easily change a leak pressure at the time of backflow prevention. An object of the present invention is to provide a power steering device using the same.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has taken the following technical measures.
That is, the present invention relates to a check valve including a valve housing, a valve seat, a movable plug, and an elastic member, wherein the valve seat is coaxial with the valve housing and is movable in an axial direction. A movable ring housed in a valve housing, the outer peripheral edge of which is in contact with the movable ring to define a movement limit of the movable ring to the discharge port side; A second elastic member is provided in the valve housing to urge the outer peripheral edge of the ring into close contact with the abutting portion.
[0009]
In this case, when the fluid flows in the forward direction from the supply port side to the discharge port side, the movable stopper moves to the discharge port side against the first elastic member due to the fluid pressure in the forward direction. As a result, a gap is formed between the movable plug and the valve seat (movable ring), and the fluid in the forward direction is discharged from the discharge port through the gap. Conversely, even if an attempt is made to flow the fluid in the opposite direction from the discharge port side to the supply port side, the fluid pressure in the opposite direction acts in the direction of pressing the movable stopper against the valve seat, so that the movable stopper supplies the fluid supply port. Backflow to the side is prevented.
[0010]
On the other hand, when the fluid pressure in the reverse direction becomes larger than a predetermined value, the movable stopper and the valve seat including the movable ring move toward the discharge port against the second elastic member. As a result, a gap is formed between the outer peripheral edge of the movable ring and the contact portion of the valve housing, and the fluid in the opposite direction leaks to the supply port side through this gap.
As described above, according to the present invention, the second elastic member is elastically deformed by the fluid pressure of the fluid in the opposite direction, thereby moving the valve seat to leak the fluid in the opposite direction to the supply port side. Therefore, even if the load of high fluid pressure is repeated, the movable plug does not deform, and the deformation prevents the original function of the check valve from being lowered.
[0011]
Further, as in the present invention, when a configuration is employed in which the second elastic member for urging the valve seat toward the discharge port side is elastically deformed to leak the fluid in the opposite direction to the supply port side, the elastic constant differs. The leak pressure at the time of backflow prevention can be changed only by replacing the elastic member. For this reason, since it is not necessary to change the shape of the movable plug delicately as in the related art, the operation of changing the leak pressure becomes very simple.
The check valve according to the present invention can be used, for example, in a power steering device (power steering) for a vehicle, and the steering device is a hydraulic actuator that outputs a steering assist force by pressure oil supplied from a hydraulic pump. A hydraulic control valve that is provided between the hydraulic pump and the hydraulic actuator and controls the supply and discharge of hydraulic oil to and from the actuator in accordance with steering; and the hydraulic oil flows backward from the hydraulic actuator to the hydraulic pump. And a check valve according to the present invention for preventing the above.
[0012]
In the steering device having the check valve according to the present invention, the pressure on the discharge port side of the valve housing is a component of the device using the check valve (for example, a ball joint or a tie rod in the case of a power steering device). If the elastic constant of the second elastic member is set so that the second elastic member starts to be elastically deformed shortly before the pressure at which the oil breaks, the backflow of the pressure oil is prevented and the kickback phenomenon is prevented. When this is prevented, it is possible to prevent the components from being damaged due to excessive pressure increase in the hydraulic cylinder.
[0013]
Further, in the check valve according to the present invention, when the second elastic member is elastically deformed and the movable ring starts to move toward the supply port, the fluid passing between the outer peripheral edge portion of the movable ring and the contact portion. It is preferable to form a relief groove in the movable ring to promote the flow of the fluid. The reason is that once the fluid pressure in the opposite direction becomes excessive and the second elastic member is elastically deformed, it is better to release the fluid pressure as quickly as possible at the beginning of the deformation, such as in a power steering device. This is because damage to the components can be reliably suppressed.
[0014]
On the other hand, in the present invention, when the movable stopper and the valve seat (movable ring) are moved to the supply port side and the fluid in the opposite direction leaks to the supply port side, the resistance of the movement is reduced only by the second elastic member. If the movable plug is to be handled, when the movable plug passes through the contact portion of the valve housing and separates from the inner peripheral surface of the valve housing, the movable plug rolls with respect to the valve seat and is twisted in the valve housing. , The check valve may malfunction.
Therefore, in the check valve of the present invention, a stopper portion that defines a limit of movement of the movable ring to the supply port side may be provided in the valve housing so that the entire movable stopper does not move toward the supply port side from the contact portion. Recommended. With this configuration, even if the movable plug and the valve seat (movable ring) move toward the supply port, the entire movable plug does not come off the inner peripheral surface of the valve housing by passing through the contact portion. It is possible to prevent a malfunction due to the twisting of the movable stopper.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 are views showing a check valve and its components according to an embodiment of the present invention, and FIG. 4 is a schematic view showing an embodiment of a power steering device incorporating the check valve. First, the overall configuration of the power steering device will be described.
[0016]
In FIG. 4, the power steering device 1 of the present embodiment includes an input shaft 2 connected to a steering handle (not shown), a pinion 3 that rotates with the rotation of the input shaft 2, and a rack 4 that meshes with the pinion 3. A housing 5 that covers the rack 4, a hydraulic cylinder 6 as a hydraulic actuator provided inside the housing 5, a hydraulic pump 7 that supplies pressure oil to the hydraulic cylinder 6, and a steering wheel interlocked with the steering wheel. A hydraulic control valve 8 for controlling the supply and discharge of pressure oil to and from the hydraulic cylinder 6.
[0017]
Both ends of the rack 4 project from openings 5a and 5b at both ends of the housing 5, and ball joints 10 and 11 are integrated with the projecting ends. Tie rods 12, 13 are attached to the ball joints 10, 11, respectively, and both ends of the rack 4 are connected to the wheels via the tie rods 12, 13. Therefore, the steering operation of the vehicle can be performed by rotating the pinion 3 through the input shaft 2 and moving the rack 4 in the axial direction (vehicle width direction) by rotating the steering handle.
[0018]
The hydraulic cylinder 6 includes a cylinder tube 6a formed by a housing 5, a piston rod 6b integrated with the rack 4, and a piston 6c integrated with the piston rod 6b, and both sides partitioned by the piston 6c. The space is configured as a first oil chamber 6d and a second oil chamber 6e. The hydraulic control valve 8 is formed of a rotary valve, and an input port 8b, a return port 8c, a first output port 8d, and a second output port 8e are formed to project from a valve housing 8a.
[0019]
Of these, the input port 8b is connected to the output port 7a of the hydraulic pump 7, and a check valve 20, which will be described later, is built in the input port 8b. On the other hand, the return port 8c is connected to the reserve tank T. The first output port 8d is connected to a first oil chamber 6d of the hydraulic cylinder 6 via a hydraulic pipe P1, and the second output port 8e is connected to a second oil chamber 6e of the hydraulic cylinder 6 via a hydraulic pipe P2. It is connected to the. The hydraulic control valve 8 supplies hydraulic oil for assisting steering force to one of the oil chambers 6d and 6e in accordance with the steering direction and the steering resistance, and simultaneously supplies hydraulic oil from the other oil chamber to the reserve tank T. Reflux.
[0020]
Next, the check valve 20 built in the input port 8b will be described with reference to FIGS. In FIG. 1, an arrow A indicates a direction (forward direction) of supplying hydraulic oil from the hydraulic pump 7 to the hydraulic control valve, and an arrow B indicates a return direction (reverse direction) of the hydraulic oil.
As shown in FIG. 1, a check valve 20 of the present embodiment includes a cylindrical valve housing 23 having a supply port 21 and a discharge port 22 for pressure oil (fluid), and a valve provided in the valve housing 23. A seat 24, a movable plug 25 housed on the discharge port 22 side of the valve seat 24 in the valve housing 23 so as to be able to freely contact and separate from the valve seat 24, and connect the movable plug 25 to the supply port 21 side. And a first elastic member 26 that urges the valve seat 24 to come into close contact with the valve seat 24.
[0021]
The valve housing 23 is formed of a hollow stepped cylindrical body having a circular cross section and a hollow portion having a large diameter portion 27 and a small diameter portion 28 integrally connected via a tapered step portion. The opening 21 of the small diameter portion 28 is the discharge port 22. On the inner peripheral side of the opening (discharge port 22) of the small-diameter portion 28, a first flange portion 29 extending in the radial direction is bent and formed, and the inner periphery of the opening (supply port 21) of the large-diameter portion 27 is formed. On the side, a second flange portion 30 extending in a radially inward direction is bent and formed.
[0022]
The movable plug 25 is formed in a short cylindrical side guide portion 32, a curved tray-shaped seal plate portion 33 integrally connected to an axial end of the side guide portion 32, and a central portion of the seal plate portion 33. It is formed as a generally bowl-shaped member composed of a disc-shaped pressure receiving portion 34 formed as described above. The seal plate portion 33 of the movable plug 25 is formed in a shape that can be in close contact with the inner peripheral edge of the ring-shaped valve seat 24, and at this time, the valve seat 24 is closed by the pressure receiving portion 34 of the movable plug 25. It has become.
[0023]
The outermost diameter of the side guide portion 32 of the movable plug 25 is slightly smaller than the inner diameter of the small-diameter portion 28, whereby the small-diameter portion of the valve housing 23 is secured with a small gap allowing the passage of pressure oil. The movable plug 25 is accommodated inside the movable member 28 so as to be movable in the axial direction. As shown in FIGS. 1 and 2, a relief groove 35 for promoting the flow of pressure oil passing between the guide portion 32 and the small-diameter portion 28 is formed in the side guide portion 32 of the movable plug 25 in the circumferential direction. They are formed at equal intervals at locations.
[0024]
The valve seat 24 of the present embodiment is not fixed in the axial direction of the valve housing 23 but is movable in the same direction, and is coaxial with the valve housing 23 and is movable in the axial direction. It is composed of a movable ring housed in 23. The movable ring is integrally formed of a receiving plate portion 36 with which the seal plate portion 33 of the movable plug 25 contacts, and an outer peripheral flange portion 37 extending from the outer periphery of the receiving plate portion 36 in the axial direction of the valve housing 23. ing.
[0025]
The outermost diameter of the outer peripheral flange portion 37 of the valve seat (movable ring) 24 is slightly smaller than the inner diameter of the large-diameter portion 27, so that a small gap allowing the passage of pressure oil is secured. The valve seat 24 is housed inside the large diameter portion 27 of the housing 23 so as to be movable in the axial direction. As shown in FIGS. 1 and 3, a relief groove 38 that facilitates the flow of pressure oil passing between the flange portion 37 and a contact portion 39 described below is formed in the outer peripheral flange portion 37 of the valve seat 24. It is formed at equal intervals at four locations in the circumferential direction.
[0026]
The tapered step portion of the valve housing 23 constitutes a contact portion 39 that defines a limit of movement of the valve seat 24 formed of a movable ring toward the discharge port 22. A stopper portion 40 is formed at the axial center of the large diameter portion 27 of the valve housing 23 by projecting a wall portion of the large diameter portion 27 radially inward. The movement limit of the valve seat 24 made of a movable ring to the supply port 21 side is defined so that 25 does not move toward the supply port 21 side from the contact portion 39.
The check valve 20 according to the present embodiment includes the first elastic member 26 that urges the movable plug 25 toward the supply port 21 to make the movable stopper 25 come into close contact with the valve seat 24, and discharges the valve seat 24 formed of a movable ring. A second elastic member 41 is provided which urges the outlet 22 side to bring the outer peripheral edge of the ring into close contact with the contact portion 39.
[0027]
Among them, the first elastic member 26 is a coil spring interposed in a compressed state between the two members so that one end thereof abuts the first flange portion 29 and the other end abuts the inner surface of the pressure receiving portion 34 of the movable plug 25. The movable stopper 25 is urged toward the supply port 21 by the spring restoring force. On the other hand, the second elastic member 41 is composed of a coil spring interposed in a compressed state between the two members so that one end thereof is in contact with the outer peripheral edge of the receiving plate portion 36 and the other end is in contact with the second flange portion 30. The valve seat 24 made of a movable ring is urged toward the discharge port 22 by the spring restoring force.
[0028]
The elastic constant of the second elastic member 41 is a pressure at which the pressure on the discharge port 22 side of the valve housing 23 damages the ball joints 10 and 11 and the tie rods 12 and 13 which are components of the power steering device 1. The value is set to such a value that the second elastic member 41 starts to be elastically deformed slightly before.
In the power steering device 1 in which the check valve 20 according to the above-described configuration is built in the input port 8b, when pressure oil is supplied from the hydraulic pump 7, the movable plug 25 is moved in the direction of arrow A (forward direction) in FIG. The hydraulic pressure is applied to the pressure receiving portion 34, and the movable stopper 25 moves toward the discharge port 22 (left side in FIG. 1) against the first coil spring 26. As a result, a gap is formed between the seal plate portion 33 of the movable plug 25 and the valve seat 24, and the forward fluid is discharged from the discharge port 22 through the gap and the relief groove 35.
[0029]
Conversely, due to the impact applied to the wheels, hydraulic pressure is generated in the return direction from the hydraulic cylinder 6 via the hydraulic control valve 8, and when the hydraulic pressure is applied in the direction of arrow B (reverse direction) in FIG. The pressure oil 25 is pressed against the valve seat 24 so that the pressure oil does not flow backward to the supply port 21 side, and the kickback phenomenon does not occur.
However, the check valve 20 of the present embodiment does not completely prevent the backflow of the pressure oil, but prevents the internal pressure of the hydraulic cylinder 6 from excessively increasing due to the leak linked to the movement of the valve seat 24. Thus, adverse effects on the ball joints 10 and 11 provided between the hydraulic cylinder 6 and the wheels are prevented.
[0030]
That is, when the oil pressure in the direction of arrow B in FIG. 1 becomes larger than a predetermined value, the movable plug 25 and the valve seat 24 formed of a movable ring move toward the discharge port 22 against the second coil spring 41. As a result, a gap is formed between the receiving plate portion 36 of the movable ring 24 and the contact portion 39 of the valve housing 23, and pressure oil in the opposite direction leaks to the supply port 21 through this gap.
[0031]
As described above, according to the check valve 20 of the present embodiment, the second coil spring 41 is elastically deformed by the pressure oil in the opposite direction which tends to flow in the direction indicated by the arrow B in FIG. Since the seat 24 is moved to leak pressure oil in the opposite direction to the supply port 21 side, the movable plug 25 is not deformed even if a high oil pressure load is repeated. It is prevented that the original function of the device is lowered. Further, since the second coil spring 41 for urging the valve seat 24 toward the discharge port 22 is elastically deformed to leak pressure oil in the opposite direction to the supply port 21 side, the elastic constant is different. It is possible to change the leak pressure at the time of backflow prevention simply by replacing the coil spring with the coil spring, and there is also an advantage that the work of changing the leak pressure is very simple.
[0032]
Furthermore, in the check valve 20 of the present embodiment, since the relief groove 38 that facilitates the flow of the pressure oil passing between the outer peripheral edge of the movable ring 24 and the contact portion 39 is formed in the movable ring 24. Once the hydraulic pressure in the opposite direction (direction of arrow B in FIG. 1) becomes excessively large and the second coil spring 41 is elastically deformed, the excessive hydraulic pressure is released as quickly as possible from the beginning of the deformation, Thereby, breakage of the components of the power steering device 1 can be suppressed more reliably.
[0033]
On the other hand, in the present invention, since the side guide portion 32 of the movable plug 25 is guided by the small-diameter portion 28, when the entire movable plug 25 passes through the contact portion 39 of the valve housing 23 and reaches the region of the large-diameter portion 27. The movable stopper 25 may roll with respect to the valve seat 24 and twist in the valve housing 23, causing malfunction of the check valve 20. However, in the check valve 20 of the present embodiment, the movable stopper 25 Is provided with the stopper portion 40 for restricting the movement of the movable stopper 25 to the supply port 21 rather than the contact portion 39, so that such a malfunction due to the twisting of the movable plug 25 can be prevented.
Note that the above-described embodiments are all examples and are not restrictive. The scope of the present invention is defined by the appended claims, and all changes within the scope equivalent to the configuration described therein are also included in the present invention.
For example, in the above embodiment, the check valve 20 is built in the input port 8b of the control valve 8, but a pipe joint is provided in the middle of a hydraulic pipe connecting the hydraulic pump 7 and the input port 8b, and a pipe joint is provided therein. It may be built in. In this case, there is an advantage that the inconvenience that the valve housing becomes large due to the built-in check valve 20 can be avoided, and it is easy to newly provide the check valve 20 in the power steering device of the existing vehicle.
[0035]
Further, the first and second coil springs 26 and 41 used for the check valve 20 may have a spring structure other than the coil shape or another elastic element.
[0036]
【The invention's effect】
As described above, according to the present invention, since the second elastic member that urges the valve seat toward the discharge port side is elastically deformed to leak the fluid in the opposite direction to the supply port side, a high fluid Even if pressure is repeatedly applied, the movable plug does not deform, preventing the deterioration of the original function as a check valve due to the deformation of the movable plug, and simply replacing the elastic member with another elastic member having a different elastic constant. Thus, the leak pressure at the time of backflow prevention can be changed, and the leak pressure can be changed very easily.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a check valve according to an embodiment of the present invention.
FIG. 2 is a front view of the movable plug viewed from a discharge port side (the left side in FIG. 1).
FIG. 3 is a front view of the valve seat as viewed from a discharge port side (the left side in FIG. 1).
FIG. 4 is a sectional view showing a schematic configuration of a power steering device.
[Explanation of symbols]
1 power steering device 6 hydraulic actuator (hydraulic cylinder)
7 hydraulic pump 8 hydraulic control valve 20 check valve 21 supply port 22 discharge port 23 valve housing 24 valve seat (movable ring)
25 movable stopper 26 first elastic member (first elastic member, coil spring)
38 Escape groove 39 Contact part 40 Stopper part 41 Second elastic member (second elastic member, coil spring)

Claims (5)

A cylindrical valve housing having a fluid supply port and a discharge port, a valve seat provided in the valve housing, and a valve seat in the valve housing so that the valve seat can be freely moved toward and away from the valve seat. A check valve comprising: a movable stopper housed on the discharge port side; and an elastic member that urges the movable stopper toward the supply port side and closely contacts the valve seat.
The valve seat is formed of a movable ring housed in the valve housing so as to be coaxial with the valve housing and movable in the axial direction,
When the outer peripheral edge of the movable ring abuts, the contact portion that defines the movement limit of the movable ring to the discharge port side, and the outer peripheral edge of the ring by urging the movable ring toward the discharge port side A check valve, wherein a second elastic member that is in close contact with the contact portion is provided in the valve housing. The elasticity of the second elastic member is set so that the pressure on the discharge port side of the valve housing becomes a pressure that damages the components of the device using the check valve, and the second elastic member starts elastically deforming slightly before the pressure. The check valve according to claim 1, wherein a constant is set. When the second elastic member is elastically deformed and the movable ring starts to move toward the supply port, a relief groove for promoting the flow of a fluid passing between the outer peripheral edge portion and the contact portion of the movable ring is formed in the movable ring. The check valve according to claim 1 or 2, wherein The stopper according to any one of claims 1 to 3, wherein a stopper for defining a limit of movement of the movable ring toward the supply port is provided in the valve housing so that the entire movable stopper does not move toward the supply port from the contact portion. Check valve as described. A hydraulic actuator that outputs a steering assist force by hydraulic oil supplied from a hydraulic pump, and a hydraulic control that is provided between the hydraulic pump and the hydraulic actuator and that controls supply and discharge of hydraulic oil to and from the actuator in accordance with steering. A power steering apparatus comprising: a valve; and a check valve for preventing pressure oil from flowing back from the hydraulic actuator to the hydraulic pump side.
A power steering device comprising the check valve according to any one of claims 1 to 4.

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