JPH074461A - Shock absorber - Google Patents

Abstract

PURPOSE:To realize the small size of a cylinder by making a bellows in a small size, and to improve the durability by preventing the generation of a crack of the bellows, in a shock absorber. CONSTITUTION:Adding to a bellows 10 whose central part is fixed to the inner end of the cylinder of a piston rod 8, and the outer peripheral end is fixed to the inner wall of a cylinder 5; a diaphragm 11 provided between the lower wall of the cylinder 5 and a fixed piston 6, whose outer peripheral end is fixed to the inner peripheral wall of the cylinder 5, and provided to cover the opening surfaces of the through holes 13 of the fixed piston 67, is provided. While the volume of a viscous liquid at the inside 7a of the tube 7A of a piston 7 is absorbed by the bellows 10, the volume of the viscous liquid is absorbed also by the diaphragm 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber used for absorbing the vibration of an object,
The present invention relates to a technique for improving the durability and the like of a bellows provided in a cylinder for hermetically containing a viscous liquid therein.

[0002]

2. Description of the Related Art As a shock absorber of this type, a bellow is conventionally provided in a cylinder together with the cylinder wall to form a liquid chamber for hermetically containing a viscous liquid.
As shown in FIG. 6, the bellows 1 has an elastically deformable member whose central portion is fixed to the inner end of the cylinder 3 of the piston rod 2 and whose outer peripheral end is fixed to the inner wall of the cylinder 3.
For example, the annular thin plate portion 1A made of rubber or the like between the central portion and the outer peripheral end portion is normally curved and bulged toward the bottom side.

When the piston rod 2 is pushed into the cylinder 3 and the movable piston 4 slides downward,
The viscous liquid inside the movable piston 4 flows out between the movable piston 4 and the bellows 1 through the small-diameter through hole. Since the center portion of the bellows 1 moves downward due to the pushing of the piston rod 2, the volume of viscous liquid (hereinafter, “increased volume”) corresponding to the volume of the piston rod 2 entering the liquid chamber overflows. Along with that, the annular thin plate portion 1A is curved upward and bulged and deformed (see FIG. 7).

[0004]

However, the conventional shock absorber as described above has the following problems. That is, the bellows 1 is the piston rod 2
It is necessary to increase the size of the annular thin plate portion 1A in advance in consideration of the bulge for absorbing the increased volume due to the invasion of the. Therefore, it is inevitable that the annular thin plate portion 1A of the bellows 1 normally has a shape that largely bulges toward the bottom side as shown in FIG.

As a result, it is necessary to set the size of the cylinder 3 in correspondence with the size of the bellows 1, which causes a problem that the size of the cylinder 3 is increased.

When the piston rod 2 is pushed in, when the annular thin plate portion 1A is bulged and deformed to the upper side, the tip of the bulged portion is largely curved and deformed (rolling), so that the bellows 1 is repeatedly used. There is also a problem that due to rolling, fatigue of the tip of the bulging portion is overlapped, cracks are likely to occur, and durability is poor.

In view of the conventional problems as described above, the present invention has a structure in which the absorbing volume other than the bellows absorbs the increasing volume of the viscous liquid caused by the intrusion of the piston rod inside the cylinder. The purpose of the present invention is to downsize the bellows, downsize the cylinder, prevent cracks in the bellows, and improve durability.

[0008]

Therefore, a shock absorber according to the present invention is provided with a substantially cylindrical cylinder in which at least a part of an upper wall and a lower wall are open, and a cylinder center which is arranged in a lower portion of the cylinder. It has a shaft portion extending along the shaft and a fixing portion protruding from the outer peripheral surface of the shaft portion and fitted and fixed to the inner peripheral surface of the cylinder, and the central axis of the shaft portion only allows liquid to flow from bottom to top. First for liquid passage equipped with a check valve that allows
A large-diameter through-hole, a fixed piston having a second large-diameter through-hole for liquid passage in the fixed part, and a fixed piston in the cylinder, which is slidably mounted on an upper side of the fixed piston. A tubular portion that extends along the cylinder center axis and that is slidably fitted to the outer peripheral surface of the shaft portion of the fixed piston and has a closed upper wall, and a cylindrical portion that projects from the outer peripheral surface of the cylindrical portion and is in sliding contact with the inner peripheral surface of the cylinder. A movable piston having a sliding contact portion, a small-diameter through hole for liquid passage in the upper wall of the tubular portion, and a third large-diameter through hole for liquid passage in the sliding contact portion; Is projected to the outside of the cylinder, and the other end of the piston rod is fixed to the upper wall of the movable piston, a spring for urging the fixed piston and the movable piston in a separating direction, and a central portion of the piston rod inside the cylinder. Fixed to the end,
A bellows having an outer peripheral end portion fixed to the inner wall of the cylinder and formed of an elastically deformable member, and is disposed between the lower wall of the cylinder and the fixed piston so as to cover the through-hole opening surface of the fixed piston. And a liquid chamber in which a viscous liquid is hermetically accommodated inside the cylinder between the bellows and the diaphragm.

[0009]

In this structure, when the protruding end of the piston rod is pressed, the movable piston slides in the cylinder in the direction of the fixed piston. As a result, the shaft portion of the fixed piston moves relative to the inside of the cylinder portion of the movable piston, and the movement of the shaft portion of the fixed piston causes the viscous liquid in the cylinder portion to be pressurized and the viscous liquid to have a small diameter. It flows out through the through hole.

On the other hand, in the bellows, the central portion of the bellows is moved downward by pushing the piston rod so that the annular thin plate portion becomes substantially flat, or the bellows is slightly on the upper side corresponding to a part of the increased volume of the viscous liquid. Swells and deforms. Further, the thin plate portion of the diaphragm is bulged and deformed in correspondence with all the increased volume of the viscous liquid, or in the case where part of the volume is absorbed by the bellows, in correspondence with the remaining increased volume. To do.

By the sliding operation of the movable piston as described above, the piston receives the large liquid resistance of the viscous liquid when the viscous liquid in the cylindrical portion flows through the through hole, and is connected to, for example, the piston rod. The shock of various devices is absorbed.

On the other hand, when the pressing force applied to the piston rod is released, the movable piston is slid upward by the elastic restoring force of the spring. The viscous liquid flowing into the cylinder from the outside of the cylinder rapidly flows into the cylinder from the through hole because the first large-diameter through hole of the fixed piston is opened by the check valve.

In this case, the central portion of the bellows moves upward due to the upward movement of the piston rod, and along with this, the annular thin plate portion bulges and returns to the lower side. Further, the thin plate portion of the diaphragm that has been bulged and deformed is deformed and restored. By the sliding operation of the movable piston as described above, the piston is
It does not receive the liquid resistance of viscous liquid so much.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In FIG. 1, the shock absorber is configured to include a cylinder 5, a fixed piston 6, a movable piston 7, a piston rod 8, a spring 9, a bellows 10, a diaphragm 11, and the like.

The cylinder 5 has a cylindrical opening 5 on its upper wall.
and a cylindrical body 5A in which a is formed and the lower wall is opened.
A cover 5B attached to the lower wall opening portion of A. A pressure relief hole 5b, which will be described later, is provided at the center of the cover 5B.

The fixed piston 6 is arranged and fixed in the lower portion of the cylinder 5. The fixed piston 6 has a shaft portion 6A extending along the central axis of the cylinder 5 and a fixed portion 6B that projects from the outer peripheral surface of the shaft portion 6A and is fitted and fixed to the inner peripheral surface of the cylinder 5. Then, a first large-diameter through hole 12 for liquid passage equipped with a check valve that allows only liquid flow from the bottom to the top is provided on the central axis of the shaft portion 6A, and the liquid passage through the fixed portion 6B. The second large through hole 13 for
Each is provided. The check valve includes the through hole 1
2, the lower small diameter hole 12a and the upper large diameter hole 12b
A ball member 14 such as a steel ball is arranged at the boundary between the spring member 15 and the large diameter hole 12b.

The movable piston 7 is slidably mounted in the cylinder 5. The movable piston 7 extends along the central axis of the cylinder 5 and has a cylindrical portion 7A whose upper wall is closed so as to be slidably fitted to the outer peripheral surface of the shaft portion 6A of the fixed piston 6, and the cylindrical portion 7A. It has a sliding contact portion 7B that projects from the outer peripheral surface and is in sliding contact with the inner peripheral surface of the cylinder 5. A small-diameter through hole 16 for liquid passage is formed in the upper wall of the cylindrical portion 7A, and a third large-diameter through hole 17 for liquid passage is formed in the sliding contact portion 7B.

The small-diameter through hole 16 in the upper wall of the cylindrical portion 7A is formed in the substantially central portion of the upper wall of the cylindrical portion 7A, and the piston rod 8
Of the piston rod 8 which communicates with the inside of the filling hole described later.
It is adapted to communicate with the inside of the cylinder 5 through a small hole 18 penetratingly formed in the connecting end portion with the movable piston 7 in the direction perpendicular to the axis.

An O-ring 19 is mounted on the inner peripheral surface of the cylindrical portion 7A of the movable piston 7 so as to keep the cylindrical portion 7A in a liquid-tight manner by being in pressure contact with the outer peripheral surface of the shaft portion 6A of the fixed piston 6.
One end of the piston rod 8 is projected to the outside of the cylinder 5 from a cylindrical opening 5a at the upper end of the cylinder 5, and
The other end is fixed to the upper wall of the movable piston 7.

Actuating members (not shown) of various devices are connected to the projecting end of the piston rod 8. The spring 9 is arranged between the fixed portion 6B of the fixed piston 6 and the sliding contact portion 7B of the movable piston 7, and urges both in the separating direction. The location of the spring 9 is not limited to this, and may be disposed between the upper wall of the cylinder 5 and a cap member (not shown) mounted on the protruding end of the piston rod 8. Good.

The central portion of the bellows 10 is fixed to the inner end portion of the cylinder 5 of the piston rod 8 by a bellows retainer 20, a bellows plate 21 and the like, and the outer peripheral end portion is secured by a bellows retainer 22, a spacer 23 and the like to the inner wall of the cylinder 5. An annular thin plate portion 10A made of an elastically deformable member, such as rubber, fixed between the central portion and the outer peripheral end portion.
However, in the normal state, the shape is curved and bulged downward. However, the bellows is not limited to this, and for example,
As shown in FIGS. 4 and 5, a bellows 30 in which the annular thin plate portion 30A is formed in a bellows shape may be used.

The diaphragm 11 is arranged between the lower wall of the cylinder 5 and the fixed piston 6, and its outer peripheral end is fixed to the inner peripheral wall of the cylinder 5, and the opening surface of each through hole 13 of the fixed piston 6 is fixed. Is disposed so as to cover. The diaphragm 11 has a shape in which the thin plate portion 11A inside the outer peripheral end portion bulges upward in the normal state. Also, the central portion of the thin plate portion 11A of the diaphragm 11 is formed thicker than others for reinforcement. However, the diaphragm is not limited to this, and, for example, as shown in FIGS.
It is also possible to use a diaphragm 31 formed of a bellows member having a bottomed tubular shape and a peripheral wall of a bellows shape, and to arrange the opening side so as to cover the opening surface of each through hole 13.

In such a structure, a liquid chamber 24 in which a viscous liquid such as silicon oil is hermetically housed inside the cylinder 5 between the bellows 10 and the diaphragm 11.
Is formed. Further, the viscous liquid is normally filled in the inside 7a of the cylindrical portion 7A of the movable piston 7.

In this case, the viscous liquid is filled in the cylinder 5 through a filling hole 25 formed through the piston rod 8 along the axial direction. After filling the viscous liquid, the resin ball 26 is inserted at the boundary between the lower small diameter hole 25a and the upper large diameter hole 25b forming the filling hole 25.
The resin ball 26 is pressed down by the hollow set 27 fitted in 5b to close the filling hole 25.

The shock absorber having the above construction operates as follows. When the projecting end of the piston rod 8 is pressed, the movable piston 7 moves into the fixed piston 6 inside the cylinder 5.
Slide in the direction of. As a result, the shaft portion 6A of the fixed piston 6 moves relative to the inside 7a of the cylinder portion 7A of the movable piston 7, and the movement of the shaft portion 6A of the fixed piston 6 causes the inside portion 7A of the cylinder portion 7A to move. The viscous liquid is pressurized, and the viscous liquid flows out through the small-diameter through hole 16 and the small hole 18.

On the other hand, the bellows 10 has its central portion moved downward by pushing the piston rod 8 and extends until the annular thin plate portion 10A becomes flat, or as shown in FIG.
The annular thin plate portion 10A slightly bulges and deforms to the upper side corresponding to a part of the increased volume of the viscous liquid accompanying the entry of the piston rod 8. In addition, all of the increased volume,
Alternatively, when a part of the increased volume is absorbed by the bellows, the thin plate portion 11A of the diaphragm 11 bulges and deforms downward (corresponding to the remaining increased volume) (see FIG. 3).
When the thin plate portion 11A of the diaphragm 11 is bulged and deformed, the air in the space below the diaphragm 11 is discharged to the outside from the pressure relief hole 5b. Further, when the bellows 30 having a bellows shape is used, the central portion moves downward as the piston rod 8 is pushed in, as shown in FIGS. In this case, the bellows 30 is in a state in which the center portion is simply moved downward, or the bellows 30 is
Therefore, when a part of the increased volume is absorbed, the annular thin plate portion 30A bulges slightly upward. On the other hand, when the diaphragm 31 made of the bellows member is used, the thin plate portion 31A forming the bottom wall portion moves downward as shown in FIG. 5 from the normal position shown in FIG. It deforms so that the peripheral wall extends.

By the sliding operation of the movable piston 7 as described above, the piston 7 has a large liquid resistance of the viscous liquid when the viscous liquid in the inside 7a of the cylindrical portion 7A flows through the small-diameter through holes 16 and 18. The shocks of various devices that are received and connected to the piston rod 8 are absorbed.

On the other hand, when the pressing force applied to the piston rod 8 is released, the movable piston 7 is slid upward by the elastic restoring force of the spring 9. The viscous liquid that has flowed into the cylinder 5 is the first of the fixed piston 6.
Since the large-diameter through hole 12 is opened by the ball member 14 which is moved upward by receiving the fluid pressure, the large-diameter through hole 12 rapidly flows into the tubular portion through the through hole 12.

In this case, the central portion of the bellows 10 moves upward due to the upward movement of the piston rod 8, and the annular thin plate portion 10A bulges and returns to the lower side (see FIG. 2). Further, the thin plate portion 11A of the diaphragm 11, which has been bulged and deformed downward by the amount of the viscous liquid flowing out, bulges and returns to the upper side. It should be noted that when the thin plate portion 11A of the diaphragm 11 returns to the bulging deformation, the diaphragm 11
External air flows into the lower space through the pressure relief hole 5b. In this case, when the bellows-shaped bellows 30 is used, as shown in FIG. 4, the central portion moves upward and returns, and when the diaphragm 31 made of the bellows member is used, the thin plate portion 31A is It moves upward and deforms and returns so that the bellows-shaped peripheral wall contracts.

Due to the sliding operation of the movable piston 7 as described above, the piston 7 does not receive much liquid resistance of the viscous liquid.

According to the shock absorber having such a structure, the central portion is fixed to the inner end of the cylinder of the piston rod 8, and the outer peripheral end is fixed to the inner wall of the cylinder 5.
In addition to 0 and 30, the lower wall of the cylinder 5 and the fixed piston 6
The diaphragms 11 and 31 are disposed between the inner peripheral wall of the cylinder 5 and the inner peripheral wall of the cylinder 5 so as to cover the opening surfaces of the through holes 13 of the fixed piston 6. The increase volume of the viscous liquid due to the entry of the piston rod 8 is absorbed by only 11 or 31, or a part of the increased volume is absorbed by the bellows 10 and 30, and the remaining increase is also made by the diaphragms 11 and 31. Since the volume is absorbed, in the bellows 10 and 30, the bulges for absorbing the volume of the viscous liquid are taken into consideration, and the annular thin plate portions 10A and 30A are previously set.
There is no need to increase the size of. Therefore, bellow 1
It is possible to prevent the annular thin plate portions 10A and 30A of 0 and 30 from having a shape that largely bulges downward in the normal state. As a result, the bellows 10, 30 and the cylinder 5 can be downsized, and the shock absorber itself can be downsized.

Further, in the bellows 10 and 30, when the piston rod 8 is pushed in, the annular thin plate portion 10A is prevented from being largely curved and deformed (rolling), and the occurrence of cracks in the bellows 10 and 30 can be suppressed. Therefore, the durability can be improved. Furthermore, diaphragm 1
Since the thin plate portions 11A and 31A at the central portions of the Nos. 1 and 31 are only bulged and deformed, there is no fear of cracks or the like.

In particular, the diaphragms 11 and 31 are made of a softer material than the bellows 10 and 30, or the diaphragms 11 and 31 are made thinner than the bellows 10 and 30. , 3
It is preferable to make 1 easily deformable so as to absorb more increased volume on the side of the diaphragms 11 and 31, whereby the occurrence of cracks in the bellows can be suppressed more effectively.

As described above, the present invention has been described with reference to the specific embodiments, but the present invention is not limited to this, and is attached to the present invention by a person skilled in the art. It should be noted that various changes and modifications can be made without departing from the scope of the appended claims.

[0035]

As described above, according to the shock absorber of the present invention, in order to hermetically store the viscous liquid in the cylinder, the absorbing action of the increased volume of the viscous liquid generated as the piston rod enters. Is mainly performed by the diaphragm provided on the lower side of the cylinder, the bellows and the cylinder can be downsized, and the shock absorber itself can be downsized.
The occurrence of cracks in the bellows can be suppressed, and the durability can be improved, which is very useful.

[Brief description of drawings]

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

FIG. 2 is a schematic view for explaining the operation of the above embodiment.

FIG. 3 is a schematic view for explaining the operation of the above embodiment.

FIG. 4 is a schematic view illustrating the operation of the above-described embodiment when a diaphragm including a bellows-shaped bellows and a bellows member is used.

FIG. 5 is a schematic view illustrating the operation of the above-described embodiment when a diaphragm including bellows-shaped bellows and bellows members is used.

FIG. 6 is a longitudinal sectional view showing a part of an example of a conventional shock absorber.

FIG. 7 is a schematic diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 5 Cylinder 6 Fixed Piston 7 Movable Piston 8 Piston Rod 10 Bellow 10A Annular Thin Plate Part 11 Diaphragm 11A Thin Plate Part 12 First Large Through Hole 13 Second Large Through Hole 14 Steel Ball 16 Small Diameter Through Hole 17 Third Large Diameter through hole 24 Liquid chamber 30 Bellows 31 Diaphragm

Claims (5)

[Claims] 1. A substantially cylindrical cylinder in which at least a part of an upper wall and a lower wall are open, a shaft portion disposed in a lower portion of the cylinder and extending along a cylinder central axis, and an outer peripheral surface of the shaft portion. A first portion for liquid passage, which has a fixing portion which projects from the inner peripheral surface of the cylinder and is fixed to the inner peripheral surface of the cylinder, and which is provided with a check valve on the central axis of the shaft portion which allows only liquid passage from the bottom to the top. Fixed piston having a large-diameter through-hole 1 and a second large-diameter through-hole for liquid passage in the fixed part, and a fixed piston in the cylinder, which is slidably mounted on the upper side of the fixed piston. A cylindrical portion that extends along a cylinder center axis and has an upper wall that is slidably fitted to the outer peripheral surface of the shaft portion of the fixed piston and is closed; and a cylindrical portion that projects from the outer peripheral surface of the cylindrical portion and slides on the inner peripheral surface of the cylinder. And a small-diameter through hole for passing a liquid on the upper wall of the cylindrical portion. Movable pistons each having a third large-diameter through hole for liquid passage, a piston rod having one end protruding outside the cylinder and the other end fixed to the movable piston upper wall, A spring for urging the piston and the movable piston in the separating direction; a bellows composed of an elastically deformable member having a center portion fixed to the cylinder inner end portion of the piston rod and an outer peripheral end portion fixed to the cylinder inner wall; A diaphragm disposed between the lower wall of the cylinder and the fixed piston so as to cover the opening surface of each through hole of the fixed piston; and the inside of the cylinder between the bellows and the diaphragm. A shock absorber comprising a liquid chamber in which a viscous liquid is hermetically stored. 2. The shock absorber according to claim 1, wherein the bellows has a shape in which an annular thin plate portion between a central portion and an outer peripheral end portion is normally curved and bulged downward. 3. The shock absorber according to claim 1, wherein the bellows has a bellows-like annular thin plate portion between a central portion and an outer peripheral end portion. 4. The diaphragm has an outer peripheral end portion fixed to an inner peripheral wall of the cylinder, and a thin plate portion inside the outer peripheral end portion is curved and bulged upward in a normal state. 3. The shock absorber described in any one of 1. 5. The shock absorber according to claim 1, wherein the diaphragm is formed of a bellows member having a substantially cylindrical shape with a bottom.