JPH08200424A - Valve structure of hydraulic buffer - Google Patents

Abstract

PURPOSE: To reduce a high frequency vibration by providing an elastic support member, provided between a valve body and mutual shaft members, for energizing a shaft member elastically in an inserting direction when the shaft member is energized in a coming off direction. CONSTITUTION: In a high piston speed area in which a fluid circulation amount circulating an inside communication hole 10b is increased, a pressure difference generated between a lower chamber B and a reservoir chamber C is also big. A clearance (t) is formed by that a push-pressed force acting to the shaft member 11 by the pressure difference overcomes the elastic support force of a push nut 17 and the shaft member 11 is push-pressed and slided downward. Therefore, as a pressure side disc valve 14 is bent by making the X point in the inner peripheral edge part side of a holding end surface 10j to which the inner peripheral upper edge part of a pressure side disc valve 13 is contacted and a Y point of the outer peripheral edge part of a washer 12 to a fulcrum, a required opening area can be obtained by the small bent amount of the valve 13 as the clearance (t) is getting bigger. Accordingly, a piston speed is changed to a direction for reducing a valve opening resistance, namely a direction for reducing a generated attenuation force characteristic as it is getting higher. It can be prevented that the attenuation force characteristic becomes unnecessarily high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve structure for a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a valve structure of a hydraulic buffer, for example, "Bottom structure of hydraulic buffer" described in Japanese Utility Model Laid-Open No. 2-146241, and Japanese Utility Model Laid-Open No. 59-32.
"Base valve structure of hydraulic shock absorber" described in Japanese Patent No. 743 is known.

First, the "bottom structure of a hydraulic shock absorber" described in Japanese Utility Model Laid-Open No. 2-146241 discloses a lower chamber B of a cylinder 21 and a reservoir chamber C defined by a piston, as shown in FIG. A base body 24 in which a pressure side flow hole 22 and an extension side flow hole 23 are formed which define a space and through which a fluid flows based on the hydraulic pressure difference generated between the two chambers B and C during the stroke of the hydraulic buffer. A fastening bolt 26 having a bending fulcrum determining washer 25 on the head 26a side of the base end and inserted through the axial center hole 24a of the base body 24 from the reservoir chamber C side to the lower chamber B direction; Reservoir chamber C of base body 24
A pressure side disc valve having an inner peripheral edge portion sandwiched and fixed between a holding end surface 24b formed on the inner peripheral portion of the side end surface and a bending fulcrum determining washer 25 to openably and closably close the pressure side flow hole 22 from the reservoir chamber C side. 27, a clamping end surface 24c formed on the inner peripheral portion of the end surface of the base body 24 on the side of the lower chamber B, and a bending fulcrum determining washer 28, the inner peripheral edge portion of which is clamped and fixed, and the extension side flow hole 23 is formed in the lower chamber. The expansion side disc valve 29 that is openably and closably closed from the B side, and the nut 30 is screwed and fastened to the fastening bolt 26 that projects to the B side of the lower chamber B of the base body 24.
The structure is such that the inner peripheral side of 7, 29 is clamped and fixed by a predetermined pressing force.

Further, in the "hydraulic shock absorber base valve structure" described in Japanese Utility Model Laid-Open No. 59-32743, both discs are formed by caulking the tip cylinder of the shaft member instead of fastening the fastening bolts and nuts. The inner peripheral side of the valve is clamped and fixed with a predetermined pressing force.

[0005]

However, in the conventional base valve structure of the hydraulic shock absorber as described above, the flexure of the compression side disc valve 27 is the outer diameter portion of the flexure fulcrum determining washer 25. Since the YY point is used as the fulcrum, the flexural rigidity increases as the opening degree of the pressure side disc valve 27 increases, and as a result, as shown in FIG.
As indicated by the dotted line in, the damping force characteristics tend to become higher than necessary in the high piston speed range.
As a vehicle, there is a problem that high frequency vibration such as harshness becomes large.

Further, the type using the fastening bolts 26 and the nuts 30 for fastening and fixing the disc valve requires a screwing process, resulting in a high processing cost, and the fastening type by caulking is Since the caulking load is high, a pressing machine with a high load is required, which causes a problem that the amount of capital investment increases and the cost increases.

The present invention has been made by paying attention to the conventional problems as described above, and reduces only the damping force characteristic in the high piston speed range without reducing the damping force in the low piston speed range. As a vehicle, a first object is to provide a valve structure of a hydraulic shock absorber capable of reducing high frequency vibrations such as harshness, and a second object is to further reduce the cost related to the fastening means. To do.

[0008]

In order to achieve the above-mentioned first object, in the valve structure of the hydraulic buffer according to claim 1 of the present invention, the two chambers are defined and the hydraulic buffer is defined. And a valve body having a flow hole and a shaft center hole through which a fluid flows based on a hydraulic pressure difference generated between the two chambers during the stroke of, and an insertion side inserted into the shaft center hole of the valve body so as to be removable in the axial direction. A shaft member having a stepped portion having a diameter larger than the shaft center hole of the valve body, and an inner peripheral edge portion sandwiched between the stepped portion of the shaft member and the valve body via an annular stepped portion serving as a bending fulcrum. A disk valve that is fixed and normally closes the flow hole, and is provided between the valve body and the shaft member and elastically applies the shaft member in the inserting direction when the shaft member is biased in the pulling direction. And an elastic supporting member for urging.

Further, in the valve structure of the hydraulic shock absorber according to the present invention, the elastic supporting member is interposed in a compressed state between the nut screwed to the tip of the shaft member and the nut and the valve body. And a coil spring.

Further, in the valve structure of the hydraulic shock absorber according to the present invention, the elastic supporting member is interposed in a compressed state between the nut screwed to the tip of the shaft member and the nut and the valve body. In the valve structure of the hydraulic shock absorber according to claim 4, in order to achieve the above-mentioned second object, the elastic supporting member is the central hole of the annular plate. A plurality of tongues are formed by a plurality of slits extending in a radial direction from the push nut, and the tongues are all bent in the same direction to stand up to form a conical upright tongue. Is a means for press-fitting the tip end of the shaft member with a predetermined pressure so that the tip of each standing tongue is engaged with and fixed to the outer circumference of the shaft member.

Further, in the valve structure of the hydraulic shock absorber according to the present invention, the valve body is fixed to the cylinder bottom of the hydraulic shock absorber as a base valve portion, and the shaft member is slidable. did.

[0012]

Since the valve structure of the hydraulic shock absorber according to claim 1 of the present invention is configured as described above, when a differential pressure is generated due to the stroke of the hydraulic shock absorber, the disk valve bends and the through hole opens. In the low piston speed range where the generated differential pressure is small, the shaft member is urged by a predetermined force in the inserting direction by the urging force of the elastic support member, and the inner peripheral portion of the disc valve is Is maintained in a state of being sandwiched and fixed with a predetermined force between the flexure fulcrum-determining annular step portion and the valve body, so that the disc valve may bend with the outer peripheral edge of the fulcrum-determining annular step portion as a fulcrum. However, in the high piston speed range where the generated differential pressure increases, the shaft member is pushed back in the direction opposite to the inserting direction against the biasing force of the elastic support member due to the differential pressure. According to The clamping force of the inner peripheral fixed part of the valve gradually decreases, and a gap is formed in the fixed part.In such a state, the outer peripheral edge of the annular step for determining the fulcrum and the inner diameter of the disc valve Since the disc valve bends around the upper edge as a fulcrum, the required opening area can be obtained even if the amount of deflection of the disc valve is small, that is, the valve opening resistance decreases and the generated damping force characteristic decreases. It will change in the direction.

Further, in the valve structure of the hydraulic shock absorber according to the present invention, the elastic support member is formed by simply pressing the central hole of the push nut constituting the elastic support member into the outer periphery of the tip end portion of the shaft member at a predetermined pressure. The mounting and fixing of can be completed. That is, the shaft member and the push nut forming the fastening means do not require threading and can be mounted with a small press-fitting load.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described.

FIG. 2 is an overall sectional view showing the valve structure of the hydraulic shock absorber according to the embodiment of the present invention. In this figure, 1 is a cylinder tube, 2 is a piston, 3 is a rebound rubber, 4 is a piston rod, 5 is an outer tube, 6 is a base, 7 is a rod guide, 8 is an oil seal, 9 is a spring seat, A is an upper chamber, B is a lower chamber, and C is a reservoir chamber.

Next, FIG. 1 is an enlarged cross-sectional view showing the base 6 portion. As shown in this figure, the base body (valve body) is formed in a state in which a lower chamber B and a reservoir chamber C are defined. 10 are provided.

An axial center hole 10a is formed in the base body 10 so as to penetrate the axial center part thereof, and the axial center hole 1 is formed.
A shaft member 11 is slidably inserted from 0 a toward the lower chamber B from the reservoir chamber C side. That is, as shown in the exploded perspective view of FIG.
A large-diameter head 1 forming a step portion in the claims at the lower end of 1a
1b is formed, and the tip edge portion of the shaft portion 11a is cut into a tapered shape. Then, the shaft portion 1 of the shaft member 11
1a includes, in order from the bottom, a washer 12, a pressure side disc valve 13, a base body 10, an extension side disc valve 14, a pressure side fulcrum determination washer 15, and a deflection amount regulation, which form an annular step portion for determining the fulcrum side on the extension side. The retainer 16 is mounted, and the push nut 17 is press-fitted into the shaft portion 11a that protrudes to the upper part of the retainer 16 at the end so that the push nut 17 and the head portion (step portion) 11b of the shaft member 11 are separated from each other. The inner peripheral portion of the member is attached in a sandwiched state.

That is, the push nut 17 constitutes the elastic supporting member in the claims, and as shown in the plan view of FIG. 4, a plurality of radially extending radial holes extend from the center hole of the annular plate 17a made of an elastic material. A plurality of tongues 17b are formed by the slits 17c, and the tongues 17b are all bent in the same direction to stand up to form a conical standing tongue.
The inner diameter of the conical upright tongue is formed to be slightly smaller than the outer diameter of the shaft portion 11a, and the central hole of the push nut 17 is press-fitted into the outer periphery of the tip portion of the shaft portion 11a with a predetermined pressure. The tip of the tongue piece 17b is engaged and fixed to the outer circumference of the shaft portion 11a.

As described above, the inner diameter of the push nut 17 is formed so as to be expandable against its elastic force. Therefore, in the press-fitting direction into the shaft portion 11a,
As shown on the left side of FIG. 5, since the inner diameter is expanded along the inclination of each tongue piece 17b, it is possible to press-fit with a small load as shown in FIG. As shown on the right side of FIG. 5, since the opening edge portion of the inner diameter is wedged into the outer peripheral surface of the shaft portion 11a,
As shown in FIG. 6, since a very large pull-out load is required, the push nut 17 once press-fitted is in a state in which the push-nut 17 is prevented from coming off, and the tongues 17b are elastically deformed so that the base body 10 is not deformed. On the other hand, the upper end of the shaft portion 11a is elastically supported so that the shaft member 11 can slide downward.

Returning to FIG. 1 in more detail, the base body 10 has an inner communication hole (flow hole) 10b for ensuring fluid flow from the lower chamber B to the reservoir chamber C and a lower portion from the reservoir chamber C. An outer communication hole 10c that secures the flow of fluid in the chamber B direction is formed. Then, on the upper surface side of the base body 10, an inner groove 10d communicating with the inner communication hole 10b and an outer groove 10 communicating with the outer communication hole 10c.
e is formed, and an annular holding end surface 10f, an extension side inner seat surface 10g, and an extension side outer seat surface 10h are formed from the inside with the grooves 10d and 10e as boundaries.
A pressure side groove 10i communicating with the inner communication hole 10b is formed on the lower surface side of the base body 10, and the pressure side groove 1 is formed.
An annular holding end surface 10j and a pressure side seat surface 10k are formed from the inside at the boundary of 0i.

The extension side disc valve 14 is
The inner peripheral portion is clamped and fixed between the annular clamping end surface 10f and the washer 15, and the outer peripheral portion is provided in contact with the inward side inner seat surface 10g and the inward side outer seat surface 10h. . In addition, this expansion side disc valve 1
4, a communication hole 14a is formed which always communicates with the lower chamber B extension side inner groove 10d.

The pressure side disc valve 13 has its inner peripheral portion clamped and fixed between the annular clamping end surface 10j and the washer 12, and the outer peripheral portion thereof on the compression side seat surface 1 side.
It is provided in contact with 0k.

Next, the operation of the embodiment will be described. (A) At Stretching Side Stroke Since the valve structure of the hydraulic shock absorber according to the embodiment is configured as described above, during the stretching side stroke of the shock absorber, the piston 2 rises inside the cylinder tube 1. Upper chamber A
Side working fluid is pressurized and the lower chamber B side is depressurized, while the piston rod 4 is withdrawn to the outside of the cylinder tube 1 to depressurize the inside of the cylinder tube 1 and the lower chamber B and the reservoir chamber C. Since a differential pressure is generated between the two, the hydraulic fluid in the reservoir chamber C is transferred to the outer communication hole 10e in the base 6.
And the expansion side disc valve 14 via the outer groove 10e.
Is opened and the lower chamber B is sucked.

(B) During pressure side stroke During the pressure side stroke of the hydraulic shock absorber, the piston 2 descends in the cylinder tube 1 to reduce the pressure of the hydraulic fluid in the upper chamber A, and the hydraulic fluid in the lower chamber B. While being pressurized,
When the piston rod 4 enters into the cylinder tube 1, the inside of the cylinder tube 1 is pressurized and a differential pressure is generated between the lower chamber B and the reservoir chamber C, so that the hydraulic fluid in the lower chamber B communicates with each other. Hole 14a, inner groove 10d, inner communication hole 10
The pressure side disc valve 13 is opened via b and the pressure side groove 10i to be discharged to the reservoir chamber C side.

A) Low piston speed range In the low piston speed range where the amount of fluid flowing through the inner communication hole 10b is small, the differential pressure generated between the lower chamber B and the reservoir chamber C is small, so the shaft member 11 Since the pressing force that acts on the push nut 17 is small and does not exceed the elastic support force of the push nut 17, as shown in the left cross section of FIG.
The inner peripheral portion of the pressure side disc valve 13 is maintained in a state of being clamped and fixed by a predetermined clamping force, and the pressure side disc is supported by the Y point of the outer peripheral edge portion of the clamping end face 10j and the Y point of the outer peripheral edge portion of the washer 12. The valve 13 bends, so that as shown in FIG. 7, it is 2/3 of the piston speed.
The damping force characteristic of the strip is obtained. That is, in the low piston speed range, sufficient damping force characteristics can be obtained as in the conventional example.

B) High piston speed range In the high piston speed range where the amount of fluid flowing through the inner communication hole 10b is large, the lower chamber B and the reservoir chamber C are located.
Since the pressure difference generated between the shaft member 11 and the shaft nut 11 also becomes large, the pressing force acting on the shaft member 11 due to the pressure difference overcomes the elastic supporting force of the push nut 17 to move the shaft member 11 downward. A gap t is formed by pressing and sliding to the above, and therefore, a point X on the inner peripheral edge side of the holding end face 10j with which the upper peripheral edge of the pressure side disk valve 13 abuts and a Y edge of the outer peripheral edge of the washer 12 is formed. The pressure side disk valve 14 bends around the point as a fulcrum, and the required opening area can be obtained with a small amount of bending of the pressure side disk valve 13 as the gap t increases.

Therefore, as the piston speed increases, the valve opening resistance decreases, that is, the generated damping force characteristic decreases. That is, FIG.
As compared with the conventional example shown by the dotted line, as shown by the solid line, it becomes possible to prevent the damping force characteristic from becoming unnecessarily high in the high piston speed range.

As described above, in the valve structure of the hydraulic shock absorber of this embodiment, the following effects can be obtained. Only the damping force characteristic in the high piston speed range is reduced without lowering the damping force in the low piston speed range, and as a result, it becomes possible to reduce high frequency vibration such as harshness in the vehicle.

By using the shaft member 11 and the push nut 17 that can be mounted with a small press-fitting load as the fastening means, it is possible to reduce the cost by reducing the equipment investment amount and to use the bolt nut as the fastening means. Compared with this, since screw processing is not required, it is possible to reduce costs.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope not departing from the gist of the present invention. Included in the present invention.

For example, in the embodiment, the present invention is applied to the base body 10 as a valve body, but it can also be applied to a piston body.

Further, in the embodiment, the case where the elastic supporting member is constituted by the push nut is shown, but the nut screwed to the tip end of the shaft member protruding toward the high pressure chamber side of the valve body, the nut and the valve body. It is also possible to use an elastic member such as a coil spring or a corrugated washer that is interposed between the two in a compressed state.

[0033]

As described above, according to the valve structure of the hydraulic shock absorber according to the first aspect of the present invention, the space between the two chambers is defined and the two spaces are generated during the stroke of the hydraulic buffer. A valve body having a flow hole and a shaft hole through which a fluid flows based on the hydraulic pressure difference, and a shaft body of the valve body, which is inserted into the shaft center hole of the valve body so as to be removable in the axial direction. A shaft member having a stepped portion having a diameter larger than the hole, and an inner peripheral edge portion is sandwiched and fixed between the stepped portion of the shaft member and the valve body via an annular stepped portion serving as a bending fulcrum, and a flow hole is normally provided. A disk valve that closes the valve body, and an elastic support member that is provided between the valve body and the shaft member and that elastically biases the shaft member in the insertion direction when the shaft member is biased in the removal direction. As a configuration equipped with, low piston speed range Only the damping force characteristic in the high piston speed region without reducing the definitive damping force to reduce the, thereby, as the vehicle, the effect is obtained that it is possible to reduce high-frequency vibrations such as harshness.

Further, in the valve structure of the hydraulic shock absorber according to claim 4, the elastic supporting member forms a plurality of tongue pieces by a plurality of slits extending radially from the central hole of the annular plate, Consists of push nuts that are bent in the same direction and erected to form a conical standing tongue.
With the configuration in which the center hole of the push nut is press-fitted into the outer periphery of the tip end portion of the shaft member at a predetermined pressure so that the tip end of each standing tongue is engaged with and fixed to the outer periphery of the shaft member, Compared to fastening, it can be installed with a smaller press-fitting load, which reduces costs by reducing the amount of capital investment. In addition, it does not require threading as compared with fastening methods using bolts and nuts, thus reducing costs. The effect of becoming is obtained.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a base portion which is a main part of a valve structure of a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is an overall sectional view showing a valve structure of a hydraulic shock absorber according to an embodiment.

FIG. 3 is an exploded perspective view showing a base portion which is a main part of the valve structure of the hydraulic shock absorber of the embodiment.

FIG. 4 is a plan view of a push nut in the hydraulic shock absorber of the embodiment.

FIG. 5 is an explanatory view showing a press-fitted and fixed state of a push nut with respect to a shaft member in the hydraulic shock absorber of the embodiment.

FIG. 6 is a characteristic diagram showing a press-fitting load and a pulling-out load of the push nut with respect to the shaft member in the valve structure of the hydraulic shock absorber of the embodiment.

FIG. 7 is a characteristic diagram of damping force with respect to piston speed in the valve structure of the hydraulic shock absorber of the embodiment.

FIG. 8 is an enlarged cross-sectional view showing a base portion which is a main portion of a valve structure of a conventional hydraulic shock absorber.

[Explanation of symbols]

 B Lower chamber (high pressure chamber) C Reservoir chamber (low pressure chamber) 10 Base body (valve body) 10a Shaft center hole 10b Inner communication hole (flow hole) 10j Clamping end face 11 Shaft member 11b Head (step) 12 Washer (fulcrum) Annular step for determination) 14 pressure side disc valve 17 push nut (elastic support member) 17a annular plate 17b tongue piece 17c slit

Claims (5)

[Claims] 1. A valve body which defines a space between two chambers and which is formed with a flow hole and a shaft hole through which a fluid flows based on a hydraulic pressure difference generated between the two chambers during the stroke of the hydraulic shock absorber, A shaft member that is inserted into a shaft center hole of the valve body so as to be freely inserted and removed in the axial direction and has a stepped portion on the insertion side that has a diameter larger than that of the shaft center hole of the valve body; and a stepped portion of the shaft member and the valve body. A disc valve having an inner peripheral edge portion sandwiched and fixed via an annular step portion serving as a bending fulcrum to normally close the flow hole, and a disc valve provided between the valve body and the shaft member and slipping out of the shaft member. And a resilient support member that resiliently biases the shaft member in the inserting direction when biased in the direction. 2. The elastic supporting member is composed of a nut screwed to the tip of the shaft member and a coil spring interposed in a compressed state between the nut and the valve body. The valve structure of the hydraulic shock absorber according to claim 1. 3. The elastic supporting member is composed of a nut screwed to the tip of the shaft member and a corrugated washer interposed in a compressed state between the nut and the valve body. The valve structure of the hydraulic shock absorber according to claim 1. 4. An elastic support member forms a plurality of tongue pieces by a plurality of slits extending in a radial direction from a center hole of an annular plate, and the tongue pieces are all bent in the same direction to stand up to form a conical standing tongue piece. A push nut in which the center hole of the push nut is press-fitted into the outer circumference of the tip end portion of the shaft member at a predetermined pressure, and the tip end of each standing tongue is engaged and fixed to the outer circumference of the shaft member. A valve structure for a hydraulic shock absorber according to claim 1. 5. The valve body is fixed to a cylinder bottom of a hydraulic shock absorber as a base valve portion, and a shaft member is slidable. Valve structure of hydraulic shock absorber.