JPH08200426A - Hydraulic buffer - Google Patents

Abstract

PURPOSE: To reduce a friction coefficient between a select valve and the inner wall surface of a bypass passage by constituting the select valve by a thermoplastic low friction resin. CONSTITUTION: A rotary valve 43 is constituted by a thermoplastic and oil-proof low friction resin material. For example, polyamide, polyimide and polyamide imide are suitable. By such constitution, a friction coefficient between the rotary valve 43 and the inner wall surface of a bypass main flow passage 41 can be reduced. Especially, in the rotary valve 43, when the side peripheral surface of a base part 51 combined with the plate stopping part 49 of an operation rod 44 is formed in a taper shape whose diameter is shrunk in the direction of the operation rod 44, the friction coefficient can be reduced more. Consequently, the operability of the rotary valve 43 can be made favorable by the operationn rod 44 without the interpose of a low friction member between the rotary valve 43 and the inner wall surface of the bypass main flow passage 41, in other words without an increase in the number of part items.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber whose damping force can be adjusted by operating a select valve.

[0002]

2. Description of the Related Art In a conventional hydraulic shock absorber, as shown in FIGS. 8 and 9, the inside of a cylinder (not shown) is a chamber A and a chamber B by a piston 2 installed at the tip of a piston rod 1. The compression side flow passage 3 and the expansion side flow passage 4 which are partitioned into 10B and are formed in the piston 2 can be closed by the compression side damping valve 5 and the expansion side damping valve 6, respectively, and the A chamber 10A and the B chamber 10B communicate with each other. A bypass flow passage 7 is formed in the piston rod 1, and a rotary valve 8 as a select valve is installed in the bypass flow passage 7 so that the flow passage area of the bypass flow passage 7 is changed. is there.

During the compression process of the hydraulic shock absorber, the compression-side damping valve 5 is flexibly deformed so that hydraulic oil flows from the B chamber 10B to the A chamber 10A, and a bottom valve mechanism (not shown) installed at the bottom of the cylinder is operated. The compression damping valve flexibly deforms, and these generate a damping force in the compression process. Further, in the extension process, the extension side damping valve 6 is opened to move from the A chamber 10A to the B chamber 1
The hydraulic oil flows to 0B, and the bending deformation of the extension side damping valve 6 at this time generates a damping force in the extension process.

Further, during the expansion and contraction process of the hydraulic shock absorber, the hydraulic oil flows through the bypass valve 7 via the rotary valve 8, and a damping force is generated mainly during the expansion process. The damping force by the bypass passage 7 and the rotary valve 8 is adjusted by operating the operation rod 9 to rotate the rotary valve 8. The operating rod 9 is press-fitted into the rotary valve 8 and caulked, and the rotary valve 8 and the operating rod 9 are made of steel like the piston rod 1.

[0005]

In the conventional hydraulic shock absorber, the rotary valve 8 has the piston rod 1 as described above.
In addition, since it is made of steel, it is considered that the low friction member 11 is installed between the piston rod 1 and the rotary valve 8 so that the rotary valve 8 easily rotates and the operability of the rotary valve 8 is improved. However, the number of parts increases.

Further, since the rotary valve 8 is made of steel, the actuator for applying the operating force to the operating rod 9 becomes large, and further, due to the inertial force acting on the rotary valve 8, the rotary valve 8 rotates. The stop position may be displaced.

Further, in the hydraulic shock absorber disclosed in Japanese Utility Model Laid-Open No. 61-1729, a rotary valve is supported by bearings,
Although this rotary valve can be easily rotated, it has the same problem as in the above embodiment, such as an increase in the number of parts, because a bearing is required.

The present invention has been made in consideration of the above circumstances, and the operability of the select valve can be improved without increasing the number of parts, and the actuator for applying an operating force to the select valve is small. It is an object of the present invention to provide a hydraulic shock absorber that can be realized and can appropriately stop the select valve at a predetermined position.

[0009]

According to a first aspect of the present invention, the inside of the cylinder is divided into two chambers by a piston installed at the tip of a piston rod, and a damping valve is provided in a piston passage formed in the piston. A bypass flow passage is formed at the end of the piston rod on the piston installation side that communicates with the two chambers in the cylinder, and a select valve is installed in the bypass flow passage to provide the bypass flow. In the hydraulic shock absorber in which the flow passage area of the passage can be changed and the select valve is operated by the operation rod penetrating the piston rod, the select valve is made of a thermoplastic low friction resin material. .

According to a second aspect of the present invention, the select valve is molded with one end portion of the operating rod according to the first aspect buried.

The invention according to claim 3 is the invention according to claim 1 or 2.
A groove is formed in at least one end of the select valve described in (1).

The invention according to claim 4 is the invention according to claim 1 or 3.
The select valve and the operating rod described in 1 are integrally molded of the same resin.

[0013]

The invention described in claim 1 has the following effects. Since the select valve is made of the thermoplastic low friction resin, the friction coefficient between the select valve and the inner wall surface of the bypass passage can be reduced. Therefore, the operability of the select valve by the operating rod can be satisfactorily implemented without interposing the low friction member between the select valve and the inner wall surface of the bypass passage, that is, without increasing the number of parts.

Furthermore, since the select valve is made of a resin material, the select valve can be made lighter. Therefore,
The actuator that applies an operating force to the operating rod can be downsized, and the inertial force of the select valve can be reduced so that the select valve can be appropriately stopped at a predetermined position.

When the hydraulic shock absorber operates, the temperature of the hydraulic oil rises and the viscosity of the hydraulic oil decreases. On the other hand, the resin forming the select valve has a higher coefficient of thermal expansion than the metal forming the piston rod, and therefore the select valve thermally expands due to the temperature rise of the hydraulic oil, and the bypass valve between the select valve and the piston rod The gap with the wall surface is reduced. Therefore, even if the viscosity of the hydraulic oil decreases due to the temperature rise of the hydraulic oil, this hydraulic oil can be prevented from leaking through the gap between the select valve and the inner wall surface of the bypass passage. Can be realized well.

Further, since the select valve is made of resin, it is possible to facilitate secondary processing of the select valve such as drilling of the select valve.

The invention according to claim 2 has the following effects. Since the resin-made select valve is molded in a state where one end of the operation rod is embedded, the work of attaching the operation rod to the select valve can be omitted, and the cost can be reduced.

The invention described in claim 3 has the following operation. Since the groove portion is provided at the end portion of the select valve, the contact surface where the end portion of the select valve contacts the inner wall surface of the bypass passage can be reduced, and at the same time, the hydraulic oil filling the groove portion functions as a lubricating oil. From these, the contact resistance between the select valve and the inner wall surface of the bypass passage can be further reduced, and the operability of the select valve can be further improved.

The invention described in claim 4 has the following operation. Since the select valve and the operating rod are integrally molded from the same resin, the weight of the combined body of the select valve and the operating rod can be reduced, and the actuator that applies the operating force to the operating rod can be made smaller and the select valve Can be appropriately stopped at a predetermined position.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a first embodiment of a hydraulic shock absorber according to the present invention.
It is sectional drawing which shows an Example. FIG. 2 is a partial cross-sectional view showing the periphery of the piston and the rotary valve of FIG. FIG.
FIG. 3 is a sectional view showing the rotary valve of FIG. 2. FIG.
FIG. 3 is an enlarged sectional view showing a part of FIG. 2 in an enlarged manner. Figure 5
FIG. 5 is a view on arrow V in FIG. 4.

In the hydraulic shock absorber 20 shown in FIG. 1, a cylinder 23 is composed of an inner tube 21 and an outer tube 22, a piston 24 is slidably arranged in the inner tube 21, and the inside of the inner tube 21 is Room A 25A
And a B chamber 25B, and a reserve chamber 26 is provided between the inner tube 21 and the outer tube 22.

A piston rod 27 is inserted in the center of the piston 24, and a contraction side channel 28 and an extension side channel 29 are alternately formed around the piston rod 27. A compression-side damping valve 30 that can close the compression-side flow passage 28 is arranged on one side of the piston 24, and an expansion-side damping valve 31 that can close the expansion-side flow passage 29 is arranged on the other side of the piston 24. Set up. The piston 24, the compression side damping valve 30, and the expansion side damping valve 31 are integrated with the piston rod 27 by a nut 24A.

During the compression process of the hydraulic shock absorber 20, the B chamber 25B
The hydraulic oil therein passes through the compression-side flow path 28 and flexibly deforms the compression-side damping valve 30 to reach the inside of the A chamber 25A, and a compression-side damping force is generated. In the process of expanding the hydraulic shock absorber 20, the A chamber 25A
The hydraulic oil therein passes through the extension side flow path 29, flexibly deforms the extension side damping valve 31 to generate an extension side damping force, and flows into the B chamber 25B.

A rod guide 32, through which the piston rod 27 passes, is fitted to one end of the inner tube 21. A cylinder cap 33 is fitted to one end of the outer tube 22 so as to cover the rod guide 32. Here, reference numeral 34 is a bush, and reference numeral 35 is an oil seal.

A base valve mechanism 36 is installed at the other end of the inner tube 21, and a base member 37 is fitted to the other end of the outer tube 22 so as to cover the base valve mechanism 36. Here, reference numeral 38 is an eye capable of supporting an axle or the like.

During the compression process of the hydraulic shock absorber 20, the B chamber 25B
The hydraulic oil therein flexibly deforms the compression-side damping valve 39 of the base valve mechanism 36 to generate a compression-side damping force, and flows into the reserve chamber 26. The compression-side damping valve 39 and the compression-side damping valve 30 generate a compression-side damping force in the compression process of the hydraulic shock absorber 20. Also, the hydraulic shock absorber 20
During the expansion process of the B, the hydraulic oil in the reserve chamber 26 passes through the expansion side check valve 40 of the base valve mechanism 36 and the B chamber 25.
It flows into B.

The piston rod 27 has a piston 2
A bypass main flow channel 41 and a bypass sub flow channel 42 as a bypass flow channel are formed at the end of the installation side of 4. The bypass main flow passage 41 extends from the end surface of the piston rod 27 in the axial direction of the piston rod 27, has a large diameter, and is opened to the B chamber 25B. Further, the bypass sub-flow passage 42 extends in the diameter direction of the piston rod 27, communicates with the bypass main flow passage 41, has a small diameter, and is opened to the A chamber 25A. Therefore, the bypass main flow path 41 and the bypass sub flow path 42 allow the A chamber 25A
And the B chamber 25B are in communication with each other.

In the bypass main flow passage 41, a rotary valve 43 as a select valve is arranged at a portion communicating with the bypass sub flow passage 42. An operation force from an outer tube (not shown) acts on the rotary valve 43 via the operation rod 44, and the rotary valve 43 is rotatable about the axis by a predetermined angle.

The rotary valve 43 is shown in FIGS.
As shown in (A), a hollow portion 45 is provided, and the hollow portion 4
An orifice 46 is formed at a position corresponding to 5. The orifice 46 extends in a direction orthogonal to the axis of the rotary valve 43 and intersects the hollow portion 45. Therefore, when the rotary valve 43 rotates by a predetermined angle, the orifice 4
6, the overlap area of the bypass sub-flow passage 42 is changed, that is, the bypass main flow passage 41, the hollow portion 45,
The flow passage area of the flow passage including the orifice 46 and the bypass sub flow passage 42 is changed. This bypass main channel 4
1, through the hollow portion 45, the orifice 46, and the bypass sub-flow path 42, in the compression process of the hydraulic shock absorber 20, the B chamber 25B
From the A chamber 25A into the A chamber 25A, the hydraulic oil flows from the A chamber 25A into the B chamber 25B during the expansion process of the hydraulic shock absorber 20. Of these, the expansion side damping force during low speed movement of the piston 24 in the expansion process is mainly changed and adjusted by changing the flow path area.

Such a rotary valve 43 is axially positioned from both sides in the bypass main flow passage 41 by stopper collars 47. One of the stopper collars 47 is retained by the stopper ring 48 from the piston rod 27.

The rotary valve 43 is made of a low friction resin material that is both thermoplastic and oil resistant.
As examples of this resin, polyamide, polyimide, and polyamide-imide are preferable, and further, fluororesin, polyether ether ketone, or polyphenylene sulfide may be used.

The operation rod 44 is a round bar, and one end of the operation rod 44 is crushed to form a substantially disk-shaped retaining portion 49 (see FIG. 3).
(B)) is processed. At the time of molding the rotary valve 43, the rotary valve 43 is molded with the retaining portion 49 of the operation rod 44 embedded, and the rotary valve 43 and the operation rod 44 are integrated.

According to the above embodiment, the following effects can be obtained. Since the rotary valve 43 is made of thermoplastic, oil-resistant, and low-friction resin material, the rotary valve 43 and the inner wall surface 50 of the bypass main flow channel 41 (FIG. 4)
The coefficient of friction between and can be reduced. In particular, in the rotary valve 43, when the side peripheral surface of the base portion 51 coupled to the retaining portion 49 of the operating rod 44 is formed in a tapered shape whose diameter is reduced in the direction of the operating rod 44, the above friction coefficient is It can be further reduced. As a result, the rotary valve 43
The operability of the rotary valve 43 by the operating rod 44 can be favorably performed without interposing a low friction member between the and the main wall surface 50 of the bypass main flow passage 41, that is, without increasing the number of parts.

Further, since the rotary valve 43 is made of a resin material, the weight of the rotary valve can be reduced. Therefore, the actuator for applying the operation force to the operation rod 44 can be downsized, and the inertial force of the rotary valve 43 can be reduced, so that the rotary position of the rotary valve 43 can be appropriately stopped at a predetermined position, and a desired damping can be achieved. You can get the power.

Further, in general, when the hydraulic shock absorber 20 is operated, the temperature of the hydraulic oil rises and the viscosity of the hydraulic oil decreases. On the other hand, the resin forming the rotary valve has a larger coefficient of thermal expansion than the metal forming the piston rod 27. Therefore, the rotary valve 43 thermally expands due to the temperature rise of the hydraulic oil, and the rotary valve 43 and the piston rod 2
Gap 52 between inner wall surface 50 of bypass main flow passage 41 of No. 7
(Fig. 4) is reduced. Therefore, even if the viscosity of the hydraulic oil decreases due to the temperature rise of the hydraulic oil,
As indicated by the arrow, it is possible to prevent leakage through the gap 52 between the select valve 43 and the inner wall surface 50 of the bypass main flow passage 41, so that the temperature compensation of the damping force can be favorably realized.

Further, since the rotary valve 43 is made of resin, the secondary processing of the rotary valve for processing the orifice 46 and the like in the rotary valve 43 can be facilitated.

Further, since the resinous rotary valve 43 is molded with the retaining portion 49 of the operation rod 44 embedded, the work of attaching the operation rod 44 to the rotary valve 43 can be omitted, and the manufacturing cost can be reduced. It can be reduced.

Furthermore, since the retaining portion 49 of the operating rod 44 is integrated with the rotary valve 43, the operating rod 44
Is prevented, and the rotary valve 43 and the operating rod 44 can be firmly integrated.

(Second and Third Embodiments) FIGS. 6A and 6B show a rotary valve in a second embodiment of the hydraulic shock absorber according to the present invention. FIG. 6A is a longitudinal sectional view thereof, and FIG. VI of A)
FIG. 6B is a view on arrow B, and FIG. 6C is a view on arrow VIC in FIG. FIG. 7 is a sectional view showing a rotary valve in a third embodiment of the hydraulic shock absorber according to the present invention. In each of these embodiments, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the hydraulic shock absorber shown in FIG. 6, a rotary valve 60 as a select valve is provided with an orifice 61 of the same diameter or different diameter. One or more orifices 61 are formed in the circumferential direction of the rotary valve 60 at a plurality of positions in the axial direction of the rotary valve 60, so that the adjustment range of the damping force when the piston 24 moves at a low speed in the expansion process of the hydraulic shock absorber is adjusted. Expanded.

A plurality of grooves 63 are formed on at least one end face 62 (both end faces 62 in this second embodiment) of the rotary valve 60. Therefore, the contact area where both end surfaces 62 of the rotary valve 60 contact the stopper collar 47 can be reduced, and at the same time, the hydraulic oil filling the groove 63 functions as a lubricating oil, so that the contact resistance between the rotary valve 60 and the stopper collar 47 is reduced. It can be further reduced, and the operability of the rotary valve 60 can be further improved.

In addition, in this embodiment, the same effect as that of the above embodiment can be obtained. In the select valve of the hydraulic shock absorber shown in FIG. 7, the rotary valve 70 and the operating rod 71 are integrally molded of the same resin. This resin is made of the same material as in the first embodiment. Therefore, according to this hydraulic shock absorber, in addition to the effects of the first and second embodiments, the total weight of the combined body of the rotary valve 70 and the operating rod 71 can be reduced, so that the operating rod 71
It is possible to further reduce the size of the actuator that applies an operating force to the rotary valve 70 and to appropriately stop the rotational position of the rotary valve 70 at a predetermined position.

[0043]

As described above, according to the hydraulic shock absorber of the present invention, the operability of the select valve can be improved without increasing the number of parts, and the actuator for applying the operating force to the select valve can be made compact. Further, the select valve can be appropriately stopped at a predetermined position.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a hydraulic shock absorber according to the present invention.

FIG. 2 is a partial cross-sectional view showing the periphery of the piston and the rotary valve of FIG.

3 (A) is a cross-sectional view showing the rotary valve of FIG. 2, and FIG. 3 (B) is a IIIB-IIIB arrow view of FIG. 3 (A).

FIG. 4 is an enlarged cross-sectional view showing a part of FIG. 2 in an enlarged manner.

5 is a cross-sectional view taken along the line VV of FIG.

FIG. 6 shows a rotary valve in a second embodiment of the hydraulic shock absorber according to the present invention, (A) is a longitudinal sectional view thereof, (B) is a view as seen from the VIB arrow of FIG. 6 (A), (C) is FIG.
It is a VIC arrow line view of (A).

FIG. 7 is a sectional view showing a rotary valve in a third embodiment of the hydraulic shock absorber according to the present invention.

FIG. 8 is a cross-sectional view showing around a piston and a rotary valve of a conventional hydraulic shock absorber.

FIG. 9 is a cross-sectional view showing the rotary valve of FIG.

[Explanation of symbols]

 20 Hydraulic Shock Absorber 21 Inner Tube 22 Outer Tube 23 Cylinder 24 Piston 25A A Room 25B B Room 27 Piston Rod 28 Compression Side Flow Path 29 Expansion Side Flow Path 30 Compression Side Damping Valve 31 Expansion Side Damping Valve 41 Bypass Main Flow Path 43 Rotary Valve 44 Control rod 46 Orifice 60 Rotary valve 62 End face 63 Groove 70 Rotary valve 71 Control rod

Claims (4)

[Claims] 1. A piston installed at the tip of a piston rod divides the interior of the cylinder into two chambers, and a damping valve can close a piston flow path formed in the piston, and the piston is installed on the piston rod. A bypass flow passage that connects the two chambers in the cylinder is formed at the end on the side, and a select valve is installed in the bypass flow passage to change the flow passage area of the bypass flow passage. However, in the hydraulic shock absorber operated by the operation rod penetrating the piston rod, the select valve is made of a thermoplastic low friction resin material. 2. The hydraulic shock absorber according to claim 1, wherein the select valve is molded in a state where one end of the operation rod is embedded. 3. The hydraulic shock absorber according to claim 1, wherein a groove is formed in at least one end of the select valve. 4. The hydraulic shock absorber according to claim 1, wherein the select valve and the operating rod are integrally molded of the same resin.