JPH10281203A - Hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a buffer to reduce a cost by a method wherein a rod guide is formed of a plate. SOLUTION: A plurality of notches 56 are formed in the outer periphery of a contact between a rod guide 26 formed of a plate and guiding a piston rod 22 and an outer shell 32 and a plurality of recessed parts 54 are formed in the surfaces, positioned facing each other, of an oil seal 42 and a rod guide 26. Some of the notches 56 and the recessed part 54 are always brought into an intercommunication state even in any relative rotation position around a shaft during assembly and oil is reliably returned from an upper chamber 52 to a reservoir chamber 34.

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 most suitable for damping the vibration of a vehicle such as an automobile.

[0002]

2. Description of the Related Art In a hydraulic shock absorber (shock absorber) generally used for an automobile, a block-shaped rod guide is mounted on an upper portion of a cylinder, and a piston rod is guided in an axial direction by the rod guide. Further, an oil seal is further provided on the upper part of the rod guide for oil sealing.

[0003]

By the way, oil leaked from the rod guide through the space between the piston rod and the rod guide by the movement of the piston rod is supplied to the rod guide through the reservoir chamber provided outside the cylinder. A through hole is formed in the rod guide in order to return to the upper end of the rod guide, and the upper portion of the cylinder communicates with the reservoir chamber through the through hole.

However, since this through-hole needs to be machined into a block-shaped rod guide, the machining is complicated and causes high costs.

[0005] An object of the present invention is to provide a hydraulic shock absorber that can reduce the overall cost by devising the structure of the rod guide and its related parts in consideration of the above fact.

[0006]

According to a first aspect of the present invention, there is provided a hydraulic shock absorber having a bottomed cylindrical cylinder having an oil chamber therein.
An outer shell coaxially arranged outside the cylinder and forming a reservoir chamber with the cylinder, a piston rod provided with a piston at one end and inserted into the cylinder, and a piston rod projected at the other end from the cylinder; ,
An oil return flow path to the reservoir chamber is formed by being bent by a plate material and provided near the opening of the cylinder, guiding the piston rod at an inner peripheral portion, contacting an outer peripheral portion with an outer shell, and providing an outer peripheral portion with a reservoir chamber. A plurality of notches are provided at a first predetermined interval and provided on the opposite side of the oil chamber through the rod guide, and slide between the piston rod and the rod guide. An oil seal for forming an upper chamber, a plurality of recesses provided at a second predetermined interval around an axis in a contact portion with the rod guide, and an oil seal for flowing oil from the upper chamber to the notch; A part of the rod guide and
A check valve for flowing oil from the upper chamber to the reservoir chamber apart from the rod guide by elastic deformation, wherein the first and second predetermined intervals are different from each other, and It is characterized in that the width dimension always overlaps even by relative rotation of the guide and the oil seal.

According to the hydraulic shock absorber having the above structure, the notch formed on the outer periphery of the rod guide bent by the plate material allows the outer shell to be in contact with the inner periphery of the outer shell even when the outer periphery of the rod guide is in contact with the inner periphery of the outer shell. And a gap is formed between them.

[0008] The plurality of notches in the rod guide are provided in the first notch.
A plurality of recesses of the oil seal are formed around the axis at a second predetermined interval,
In addition, any one of these recesses and notches always overlaps due to the relative rotation between the rod guide and the oil seal in consideration of the width dimension.

Therefore, the oil in the cylinder enters the upper chamber due to the movement of the piston rod, and when the pressure in the upper chamber increases, the check valve is opened and the oil passes. The oil that has passed through the check valve reaches the reservoir chamber through an overlapping portion between the concave portion of the oil seal and the notch of the rod guide.

Therefore, even when the rod guide and the oil seal are mounted at an arbitrary angle around the axis during assembly of the hydraulic shock absorber, all the recesses are not closed by the rod guide. Is opened to allow communication with the notch.

According to a second aspect of the present invention, in the hydraulic shock absorber according to the first aspect, a part of the outer shell is projected inward as an axial stopper of the rod guide, and this projection is formed around the third axis. A plurality of the predetermined intervals are formed, and the third predetermined interval is different from the first predetermined interval formed on the rod guide. There is no limitation on the degree of the difference when the first to third intervals are different (that is, the numbers of the concave portions and the notches are different), and any combination that enables appropriate production and assembly and withstands use is possible. I just need.

In the hydraulic shock absorber having the above-described structure, a plurality of protrusions are formed on the outer shell inwardly, that is, toward the piston rod at a third predetermined interval, so as to abut on the rod guide. In this way, even when the rod guide receives a pressing force due to its contact in the final step on the extension side, the rod guide supports the piston by transmitting the pressing force to the outer shell through the protrusion.
Moreover, a plurality of the protrusions are formed around the axis at a third predetermined interval, and the interval is different from the first predetermined interval of the plurality of cutouts formed in the rod guide. Even if some of the protrusions block the notches in the rod guide, the other protrusions will be located at positions that do not correspond to the notches in the rod guide, and the rod guide will reliably support the axial force of the piston rod In addition, even when the rod guide is attached to the shock absorber at an arbitrary attachment angle around the axis, the oil return flow path can be reliably ensured.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Overall Configuration) FIG. 1 shows a hydraulic shock absorber 10 to which an embodiment of the present invention is applied. In FIG. 1, an arrow UP indicates an upward direction, and an arrow DW indicates a downward direction. The hydraulic shock absorber 10 is mounted on a vehicle body or wheels (not shown) with its axial center arranged in a vertical direction.

The hydraulic shock absorber 10 includes a cylindrical cylinder 12 having a straight shaft and constituting a shock absorber main body.
A base case 14 is attached to the lower end of the cylinder 12 to close the lower end of the cylinder 12. Further, the inside of the cylinder 12 is filled with oil, and an upper liquid chamber 18A is provided above the piston 16 provided coaxially inside the cylinder 12, and a lower liquid chamber 18B is provided below.

A lower end of a rod-shaped piston rod 22 is fixed to the piston 16, and an upper end protrudes above the cylinder 12 and is attached to a vehicle body (not shown). Further, an orifice 24 is formed in the piston 16, and when the piston 16 moves up and down inside the cylinder 12, the vibration is attenuated by the flow resistance when the oil in the cylinder 12 passes through the orifice 24.

At the upper end of the piston rod 22 from the piston 16, a rebound stopper 58 formed coaxially of a rubber material or a soft synthetic resin material is provided coaxially.

(Structure of Rod Guide 26) As shown in detail in FIG. 2, a rod guide 26 formed by bending a metal plate by press working or the like is provided at the upper end of the cylinder 12. I have. The rod guide 26 has a cylindrical inner tube portion 26A formed therein.
When the piston rod 16 penetrates and moves up and down, the piston rod 16 is guided in the axial direction. Further, the inner peripheral portion of the inner cylindrical portion 26A (that is, the portion facing the outer peripheral portion of the piston rod 16).
A seal member 28 is attached to the seal member 28. The seal member 28 comes into contact with the outer peripheral portion of the piston rod 16 to reduce frictional resistance when the piston rod 16 moves up and down.

The rod guide 26 has an outer cylindrical portion 26B which is larger in diameter and coaxial with the inner cylindrical portion 26A. The outer cylinder 26B is press-fitted into the inner periphery of the cylinder 12. A portion near the upper end of the outer cylindrical portion 26B is a large-diameter portion 26D having a slightly larger outer diameter than the vicinity of the lower end, and adjusts a press-fit when the press-fitting is performed into the inner periphery of the cylinder 12. Further, a flat plate portion 26E bent in the radial direction is continuous with the upper end portion of the outer cylindrical portion 26B, abuts against the upper end portion of the cylinder 12, and prevents the rod guide 26 from moving downward. A small cylindrical portion 26F having a short axial dimension is continuous from the outer peripheral end of the flat plate portion 26E, and the upper end of the small cylindrical portion 26F is continuous with a flat plate portion 26G arranged substantially parallel to the flat plate portion 26E. The outer peripheral portion of the flat plate portion 26G is
The outer shell 32 and the cylinder 12 are coaxially arranged outside of the outer shell 32 and abut on the inner peripheral portion of the outer shell 32 constituting the shock absorber main body together with the cylinder 12. A reservoir chamber 34 is provided between the outer shell 32 and the cylinder 12, and is filled with a low-pressure nitrogen gas, which is an inert gas.

As shown in FIG. 1, the outer shell 32
A lower cap 36 fixed below the base case 14 is fitted inward at the lower end of the base shell 14, whereby a coaxial arrangement with the lower part of the cylinder 12 is ensured also at the lower part of the outer shell 32. A ring-shaped mounting member (not shown) is fixed to the lower cap 36 to support a wheel (not shown). In addition, reservoir room 3
The lower part of 4 is communicated with the lower liquid chamber 18B via a communication passage (not shown).

On the other hand, as shown in FIG.
B between the lower end of B and the lower end of the inner cylinder 26A.
C is formed, and the outer tube portion 26B and the inner tube portion 26A are integrally connected by the flat plate portion 26C. The lower surface of the flat plate portion 26C is a plane substantially perpendicular to the axial direction of the piston rod 16, and the piston rod 22
1 moves upward by a predetermined stroke, the rebound stopper 58 shown in FIG. 1 abuts against the lower surface of the flat plate portion 26C to limit further upward movement of the piston rod 22 (that is, rebound). Stopper 58
Is in contact with the lower surface of the flat plate portion 26C is the stroke end in the extension direction of the piston rod 22).

(Structure of Oil Seal 42) An oil seal 42 is disposed above the rod guide 26. As shown in detail in FIG. 5, the oil seal 42 has a disk-shaped seal body 44 made of a hard synthetic resin or metal, and has a seal member 46 made of a soft synthetic resin on the inner periphery and upper and lower surfaces of the seal body 44. Is attached. The lower surface near the outer peripheral portion of the seal body 44 contacts the flat plate portion 26G of the rod guide 26 and is prevented from moving downward. On the outer peripheral portion of the seal body 44, a cylindrical portion 44A having a short axial dimension is integrally and continuously raised. A top portion of the cylindrical portion 44A hits an upper end portion of the outer shell 32 with a swaging deformed portion 32A bent inward in the radial direction.
Thus, upward movement of the seal body 44 is prevented.

An inner peripheral portion of the seal body 44 is provided with a space between the outer peripheral portion of the piston rod 22 and a branch arm 46B having an inner peripheral portion of the seal member 46 bifurcated.
46C is provided. These branch arms 46B,
The vicinity of the distal end of 46C elastically adheres to the outer peripheral portion of the piston rod 22. Further, a ring-shaped spring member 48 is attached to the outer periphery of the lower end of one branch arm 46C, and the seal member 46 at this portion is in close contact with the outer periphery of the piston rod 22 to seal oil. Further, a part of the seal member 46 is extended downward so that the rod guide 2
6 and a check valve 46A.

That is, an upper chamber 52 is formed between the rod guide 26 and the oil seal 42 so that the oil that has risen from the upper liquid chamber 18A through the gap between the piston rod 22 and the seal member 28 enters. The upper room 5
When the pressure of the oil in the second chamber 2 increases, the check valve 46A is elastically deformed to allow the oil in the upper chamber 52 to pass.

(Structure of Oil Return Channel) Here, as shown in FIGS. 4 and 5, the lower surface of the oil seal 42 has a substantially semicircular A plurality of recesses 54 are formed. As shown in FIG. 2, these recesses 54 form a gap between the recesses 54 and the flat plate portion 26 </ b> G of the rod guide 26 and deform the check valve 46 </ b> A from the upper chamber 52 to allow the oil flowing out to pass therethrough. I have. As shown in FIG. 3, a plurality of notches 56 are formed in the outer peripheral portion of the flat plate portion 26G of the rod guide 26, and have a role of returning oil flowing out through the concave portion 54 to the reservoir chamber 34. I have.

Here, the intervals around the axis where the concave portion 54 and the notch 56 are formed are different from each other. That is, in the present embodiment, as shown in FIG. 4, a total of six concave portions 54 are formed at intervals of 60 ° (concave portions 54A to 54A).
F), as shown in FIG. 3, a total of five notches 56 (notches 56A to 56E) are formed at intervals of 72 °.
As described above, the forming angles are different from each other, and the width L1 of each recess 54 and the width L of each notch 56 are different.
2 means that any recess 54 and any notch 56 overlap and communicate with each other regardless of the relative rotation position by rotating the rod guide 26 and the oil seal 42 coaxially. ing.

That is, the recess 54 and the notch 56 in the state shown in FIGS. 3 and 4 are different from each other by one in number.
A overlaps, and from this state, when the rod guide 26 of FIG. 3 is gradually rotated counterclockwise with respect to the oil seal 42 of FIG. 4, the overlapping portion between the recess 54A and the notch 56A decreases, Eventually the recess 54A
Is displaced from the notch 56A, and the overlapped portion disappears.
However, at this point, the recess 54B has already started to overlap the notch 56B to form an overlap portion. further,
The rod guide 26 is rotated in the counterclockwise direction to
When B shifts from the notch 56B and the overlapping portion disappears, the concave portion 54C starts to overlap the notch 56C, and an overlapping portion is formed.

As described above, since the recesses 54A to 54F and any of the notches 56A to 56E always overlap and communicate with each other at any relative rotational position, the rod guide 2
When the oil seal 6 and the oil seal 42 are assembled at an arbitrary angle around the axis, the recess 54 and the notch 56
A flows from the upper chamber 52 through the reservoir chamber 34 through the reservoir chamber 34.
You can always return to.

(Structure of punch caulking portion 62) As shown in FIG.
Pressing force is applied by a punch jig (not shown) radially inward (that is, in the direction of arrow F in FIG. 2) corresponding to the upper side of G to form a punch caulking portion 62 as a projecting portion projecting inward. Have been. The punch caulking portion 62 is configured such that a rebound stopper 58 (see FIG. 1) fixed to an axially intermediate portion of the piston rod 22 extends toward the extension side of the piston rod 22 (in FIG. 1, the piston rod 22 is located above the cylinder 12). When the actuator moves by the maximum amount and reaches the stroke end corresponding to the flat plate portion 26C of the rod guide 26, the load applied to the rod guide 26 is reliably supported by the outer shell 32.

In the present embodiment, the punch caulking section 62
Are formed at four positions at 45 ° intervals around the axis, whereby the interval between the punch caulking portions 62 and the notches 56 (72
(Five intervals at an angle of 5 °) are also different from each other, and the arrangement is such that the punch caulking portion 62 does not block all the concave portions 54.

That is, the outer shell 32 provided with four punch caulking portions 62 at 45 ° intervals and the rod guide 26 shown in FIG. The notches 56A to 56E are provided in the punching
Thus, only one position is closed at a maximum, and the load can be reliably supported by the other punch caulking portion 62.

(Operation of the present embodiment) When vibration is generated by running of the vehicle, the vehicle body and the wheels move up and down relatively, so that the piston rod 22 moves up and down with respect to the cylinder 12. In this case, the oil in the upper liquid chamber 18A and the oil in the lower liquid chamber 18B are moved to the orifice 24 by the vertical movement of the piston 16.
Vibration is absorbed by the flow resistance when passing through.

When the oil pressure in the upper liquid chamber 18A increases due to the vertical movement of the piston rod 22 or when the piston rod 22 moves largely upward, a part of this oil becomes between the piston rod 22 and the rod guide 26. Through to the upper chamber 52. When the amount of oil flowing into the upper chamber 52 increases, the pressure in the upper chamber 52 rises, and the oil in the upper chamber 52 elastically deforms the check valve 46A, and
4. Through the notch 56, it reaches the reservoir chamber 34. The oil in the reservoir chamber 34 returns to the inside of the cylinder 12 through a through hole (not shown) provided below the cylinder 12 by the pressure of the low-pressure nitrogen gas.

Here, as described above, the concave portion 54,
Since the interval between the notch 56 and the notch 56 is shifted, and any one of them is always in a communication state in any relative rotation,
Oil from the upper chamber 52 can reliably return to the reservoir chamber 34.

[0034]

According to the present invention having the above-described structure, the rod guide can be formed by a plate-like member, and has an excellent effect that the entire structure can be reduced with a simple structure.

[Brief description of the drawings]

FIG. 1 is an overall cross-sectional view showing a hydraulic shock absorber according to an embodiment of the present invention, cut along an axial direction.

FIG. 2 is an enlarged sectional view showing the vicinity of the upper end of FIG.

FIG. 3 is a bottom view of a rod guide of the hydraulic shock absorber according to one embodiment of the present invention.

FIG. 4 is a bottom view of the oil seal of the hydraulic shock absorber according to one embodiment of the present invention.

FIG. 5 is a sectional view of an oil seal of the hydraulic shock absorber according to the embodiment of the present invention, cut along an axial direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic shock absorber 12 Cylinder 16 Piston 22 Piston rod 26 Rod guide 32 Outer shell 34 Reservoir chamber 42 Oil seal 46A Check valve 52 Upper chamber 54 Depression 56 Notch 62 Punching part (projection part)

Claims (2)

[Claims] A bottomed cylindrical cylinder having an oil chamber inside; an outer shell coaxially arranged outside the cylinder and forming a reservoir chamber with the cylinder; and a piston at one end side. A piston rod that is provided and inserted into the cylinder, the other end of which protrudes from the cylinder, is formed by bending a plate material, and is provided near an opening of the cylinder, and guides the piston rod at an inner peripheral portion and an outer peripheral portion. A plurality of notches forming a plurality of notches at a first predetermined interval on the outer peripheral portion, the cutouts constituting an oil return flow path to the reservoir chamber; and an oil chamber through the rod guide. It is provided on the opposite side, slides with the piston rod, forms an upper chamber between the rod guide and the rod guide, and abuts on the rod guide around the axis. A plurality of recesses are provided at a second predetermined interval, and an oil seal that allows oil to flow from the upper chamber to the notch; and a rod guide that is provided in a part of the oil seal and separates from the rod guide by elastic deformation. A check valve that allows oil to flow from the upper chamber to the reservoir chamber, wherein the first and second predetermined intervals are different from each other, and the recess and the notch are provided for relative rotation between the rod guide and the oil seal. A hydraulic shock absorber characterized in that it has a width dimension that always overlaps depending on the size. 2. A part of the outer shell protrudes inward as an axial stopper of the rod guide, and a plurality of protrusions are formed around the axis at a third predetermined interval. 2. The hydraulic shock absorber according to claim 1, wherein the interval is different from the formed first predetermined interval.