JP3237962B2 - shock absorber - Google Patents

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 vibration of an object, and more particularly,
The present invention relates to a technique for improving durability and the like of a bellow provided in a cylinder for hermetically storing a viscous liquid inside the cylinder.

[0002]

2. Description of the Related Art As a shock absorber of this type, a bellows is conventionally provided in a cylinder together with a 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 having a center portion fixed to the inner end of the piston 3 of the piston 3 and an outer end fixed to the inner wall of the cylinder 3.
For example, it is made of rubber or the like, and the annular thin plate portion 1A between the central portion and the outer peripheral portion has a shape which bulges toward the bottom in a normal state.

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 from the small-diameter through hole. The center of the bellows 1 moves downward due to the pushing of the piston rod 2, and the volume of the viscous liquid (hereinafter, “increased volume”) corresponding to the volume of the piston rod 2 that has entered the liquid chamber overflows. Accordingly, the annular thin plate portion 1A bends upward and swells and deforms (see FIG. 7).

[0004]

However, the conventional shock absorbers described above have the following problems. That is, the bellows 1
It is necessary to increase the size of the annular thin plate portion 1A in advance in consideration of the swelling for absorbing the increased volume accompanying the intrusion. For this reason, it is inevitable that the annular thin plate portion 1A of the bellows 1 normally has a shape which greatly bulges to the bottom as shown in FIG.

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

When the annular thin plate portion 1A swells and deforms upward when the piston rod 2 is pushed in, the bellows 1 deforms (rolls) because the tip of the swelling portion is greatly curved and deformed (rolling). There is also a problem that the rolling causes the fatigue at the tip of the bulging portion to be overlapped, cracks to be easily generated, and poor durability.

The present invention has been made in view of the above-mentioned conventional problems, by increasing the volume of viscous liquid caused by the penetration of a piston rod inside a cylinder by means of an absorbing portion other than a bellows. It is another object of the present invention to reduce the size of the bellows, to reduce the size of the cylinder, and to prevent the occurrence of cracks in the bellows, thereby improving the durability.

[0008]

Therefore, a shock absorber according to the present invention has a substantially cylindrical cylinder having at least a part of an upper wall and a lower wall opened, and is disposed at a lower portion inside the cylinder. A shaft portion extending along the shaft, and a fixed portion projecting from the outer peripheral surface of the shaft portion and fitted and fixed to the inner peripheral surface of the cylinder, and the center shaft of the shaft portion has only a liquid flow from bottom to top. The first for the passage of liquid 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 slidably loaded above the fixed piston in the cylinder, A cylindrical portion which extends along the cylinder center axis and is slidably fitted to the outer peripheral surface of the shaft portion of the fixed piston, and whose upper wall is closed; A movable piston having a sliding contact portion, a small-diameter through-hole for liquid passage in the upper wall of the cylindrical portion, and a third large-diameter through-hole for liquid passage in the sliding contact portion; A piston rod having the other end fixed to the upper wall of the movable piston, a spring for urging the fixed piston and the movable piston in a direction away from each other, and a center portion inside the cylinder of the piston rod. Fixed to the end,
An outer peripheral end is disposed between the lower wall of the cylinder and a fixed piston, and a bellows made of an elastically deformable member fixed to the inner wall of the cylinder so as to cover each through hole opening surface of the fixed piston. And a liquid chamber for hermetically containing a viscous liquid inside the cylinder between the bellows and the diaphragm.

[0009]

In this configuration, when the protruding end of the piston rod is pressed, the movable piston slides in the direction of the fixed piston in the cylinder. As a result, the shaft portion of the fixed piston relatively moves within the cylinder portion of the movable piston, and by moving the shaft portion of the fixed piston, the viscous liquid in the cylinder portion is pressurized and the viscous liquid is reduced in diameter. It flows out through the through hole.

[0010] On the other hand, the bellows moves downward at the center by pushing the piston rod, and its annular thin plate portion becomes almost flat, or slightly on the upper side corresponding to a part of the increased volume of the viscous liquid. It swells and deforms. Further, the thin plate portion of the diaphragm swells and deforms corresponding to all of the increased volume of the viscous liquid, or corresponding to the remaining increased volume when the bellows absorbs a part of the volume. I do.

By the sliding operation of the movable piston as described above, the piston receives a 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. Shocks of various devices are 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 that has flowed out of the cylinder in the cylinder quickly 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 is moved upward by the upward movement of the piston rod, whereby the annular thin plate portion swells downward and returns to the deformed state. Further, the thin plate portion of the diaphragm that has been swollen and deformed returns to the deformed state. By the sliding operation of the movable piston as described above, the piston is
Low resistance to viscous liquid.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, the shock absorber includes 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.
a is formed and the lower wall is opened.
A and a cover 5B attached to the lower wall opening of A. At the center of the cover 5B, a pressure relief hole 5b described later is provided.

The fixed piston 6 is disposed and fixed at a lower part in 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 projecting from the outer peripheral surface of the shaft portion 6A and fitted and fixed to the inner peripheral surface of the cylinder 5. A first large-diameter through-hole 12 for liquid passage equipped with a check valve that allows only liquid flow from bottom to top is provided in the center axis of the shaft portion 6A, and a liquid passage is provided in the fixed portion 6B. Second large-diameter through hole 13 for
Each is provided. The check valve is provided in the through hole 1.
2 and the upper large-diameter hole 12b
A spring pin 15 for restricting upward movement of the ball member 14 is fitted and fixed in the large-diameter hole 12b.

The movable piston 7 is slidably loaded in the cylinder 5. The movable piston 7 extends along the central axis of the cylinder 5, and has a closed cylinder 7 A whose upper wall is slidably fitted on the outer peripheral surface of the shaft 6 A of the fixed piston 6. And a sliding contact portion 7B projecting from the outer peripheral surface and slidingly contacting 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 substantially at the center of the upper wall of the cylindrical portion 7A,
Of the piston rod 8
Is connected to the inside of the cylinder 5 through a small hole 18 penetratingly formed in the direction perpendicular to the axis at the connection end with the movable piston 7.

An O-ring 19 is mounted on the inner peripheral surface of the cylindrical portion 7A of the movable piston 7 so as to press against the outer peripheral surface of the shaft portion 6A of the fixed piston 6 to maintain the inside of the cylindrical portion 7A in a liquid-tight manner.
The piston rod 8 has one end protruding outside the cylinder 5 from a cylindrical opening 5a at the upper end of the cylinder 5,
The other end is fixed to the upper wall of the movable piston 7.

Operating members (not shown) of various devices are connected to the protruding end of the piston rod 8. The spring 9 is disposed 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 provided between the upper wall of the cylinder 5 and a cap member (not shown) attached to the protruding end of the piston rod 8. Good.

The bellows 10 have a central portion fixed to the inner end of the cylinder 5 of the piston rod 8 by a bellows retainer 20, a bellows plate 21 and the like, and an outer peripheral end formed by a bellows retainer 22, a spacer 23 and the like. Is formed of an elastically deformable member, for example, rubber or the like, which is fixed to the annular thin plate portion 10A between the center portion and the outer peripheral end portion.
However, in a normal state, it has a shape that bulges downwardly. However, the bellows is not limited to this. 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 can be used.

The diaphragm 11 is disposed between the lower wall of the cylinder 5 and the fixed piston 6, and the 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 provided. It is arranged to cover. The diaphragm 11 has a shape in which the thin plate portion 11A inside the outer peripheral end swells upward in a normal state. The central portion of the thin plate portion 11A of the diaphragm 11 is formed thicker than the others for reinforcement. However, the diaphragm is not limited to this. For example, as shown in FIGS.
A diaphragm 31 made of a bellows member having a bottomed cylindrical shape and a peripheral wall having a bellows shape may be used, and the opening side thereof may be arranged so as to cover the opening surface of each through hole 13.

In such a configuration, a liquid chamber 24 in which a viscous liquid such as silicone oil is hermetically stored in the cylinder 5 between the bellows 10 and the diaphragm 11.
Is formed. The interior 7a of the cylindrical portion 7A of the movable piston 7 is normally filled with a viscous liquid.

In this case, the viscous liquid is filled into the cylinder 5 through a filling hole 25 formed through the piston rod 8 along the axial direction. After filling the viscous liquid, a resin ball 26 is inserted into the boundary between the lower small hole 25a and the upper large hole 25b constituting the filling hole 25, and the large diameter hole 2 is formed.
The resin ball 26 is pressed by the hollow set 27 fitted in 5b, and the filling hole 25 is closed.

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

On the other hand, the center of the bellows 10 moves downward by the pushing of 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 swells and deforms upward in accordance with a part of the increased volume of the viscous liquid accompanying the entry of the piston rod 8. Further, all of the increasing volumes,
Alternatively, when a part of the increased volume is absorbed by the bellows, the thin plate portion 11A of the diaphragm 11 expands and deforms to the lower side in accordance with the remaining increased volume (see FIG. 3).
When the thin plate portion 11A of the diaphragm 11 swells and deforms, the air in the space below the diaphragm 11 is discharged to the outside through the pressure release hole 5b. In addition, when the bellows-like bellows 30 is used, as shown in FIGS. 4 and 5, the center portion moves downward as the piston rod 8 is pushed. In this case, the bellows 30 may be in a state where the center portion is simply moved downward, or
Accordingly, when a part of the increased volume is absorbed, the annular thin plate portion 30A slightly swells and deforms upward. On the other hand, when the diaphragm 31 made of a bellows member is used, as shown in FIG. 5, the thin plate portion 31A constituting the bottom wall portion moves downward from the normal position shown in FIG. Deforms so that the surrounding wall extends.

By the sliding operation of the movable piston 7 as described above, the piston 7 causes 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. As a result, shocks of various devices 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 flowing into the cylinder 5
The large-diameter through-hole 12 is opened by the ball member 14 that has been moved upward by receiving the fluid pressure, so that the large-diameter through-hole 12 quickly flows into the cylindrical portion from the through-hole 12.

In this case, the central portion of the bellows 10 is moved upward by the upward movement of the piston rod 8, and the annular thin plate portion 10A swells downward and returns to the deformed state (see FIG. 2). Further, the thin plate portion 11A of the diaphragm 11, which has been swelled and deformed downward by the amount of the viscous liquid flowing out, is swelled and returned to the upper side. 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-like bellows 30 is used, as shown in FIG. 4, the center portion moves upward and returns, and when the diaphragm 31 made of a bellows member is used, the thin plate portion 31A becomes It moves upward and deforms and returns to shrink the belly-shaped peripheral wall.

By 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 bellows 1 having the center portion fixed to the inner end portion of the piston rod 8 and the outer end portion fixed to the inner wall of the cylinder 5.
0, 30 plus the lower wall of cylinder 5 and fixed piston 6
, The outer peripheral end portion of which is fixed to the inner peripheral wall of the cylinder 5, and the diaphragms 11 and 31 are provided so as to cover the opening surfaces of the respective through holes 13 of the fixed piston 6. The increased volume of the viscous liquid accompanying the intrusion of the piston rod 8 is absorbed only by the pistons 11 and 31, or a part of the increased volume is absorbed by the bellows 10 and 30 and the remaining increase by the diaphragms 11 and 31. Since the volume is absorbed, in the bellows 10 and 30, the annular thin plate portions 10A and 30A are previously taken into consideration in consideration of the swelling for absorbing the volume of the viscous liquid.
There is no need to increase the size of. For this reason, Bellow 1
It is possible to prevent the annular thin plate portions 10A, 30A of 0, 30 from having a shape that swells greatly toward the lower side in a normal state. As a result, the bellows 10, 30 and the cylinder 5 can be reduced in size, and the shock absorber itself can be reduced in size.

Further, the bellows 10, 30 are prevented from deforming (rolling) due to the large bending of the annular thin plate portion 10A when the piston rod 8 is pushed in, and the generation of cracks in the bellows 10, 30 can be suppressed. Thus, durability can be improved. In addition, diaphragm 1
In Nos. 1 and 31, only the thin plate portions 11A and 31A at the central portion are swelled and deformed, and thus there is no concern about cracks or the like.

In particular, the diaphragms 11 and 31 are made of a more flexible material than the bellows 10 and 30, or the diaphragms 11 and 31 are made thinner than the bellows 10 and 30 to make the diaphragm 11 or 31 thinner. , 3
It is preferable that the diaphragm 1 be easily deformed so that a larger amount of increased volume can be absorbed on the diaphragms 11 and 31 side, whereby the generation 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. However, the present invention is not limited to these embodiments, 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 inside the cylinder, the absorbing action of the increased volume of the viscous liquid generated as the piston rod enters. Is performed mainly by the diaphragm provided on the lower side of the cylinder, so that the bellows and the cylinder can be downsized, and the shock absorber itself can be downsized.
This is a great utility that can suppress the occurrence of cracks in the bellows and improve the durability.

[Brief description of the drawings]

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

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

FIG. 3 is a schematic diagram illustrating the operation of the embodiment.

FIG. 4 is a schematic diagram for explaining the operation of the above embodiment when a diaphragm made of a bellows and a bellows member is used.

FIG. 5 is a schematic view for explaining the operation of the above embodiment when a diaphragm made of bellows and a bellows member 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 illustrating the operation of the conventional example.

[Explanation of symbols]

 Reference Signs List 5 cylinder 6 fixed piston 7 movable piston 8 piston rod 10 bellows 10A annular thin plate portion 11 diaphragm 11A thin plate portion 12 first large-diameter through hole 13 second large-diameter through-hole 14 steel ball 16 small-diameter through-hole 17 third large Diameter through hole 24 Liquid chamber 30 Bellows 31 Diaphragm

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-34233 (JP, A) JP-A-2-62148 (JP, U) JP-A-58-45440 (JP, U) JP-A-59-45440 27344 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 9/10

Claims (5)

(57) [Claims] 1. A substantially cylindrical cylinder having at least a part of an upper wall and a lower wall opened, a shaft disposed in a lower portion of the cylinder, extending along a cylinder center axis, and an outer peripheral surface of the shaft. And a fixing portion which is fitted and fixed to the inner peripheral surface of the cylinder so as to protrude from the cylinder, and the central axis of the shaft portion is provided with a check valve for allowing liquid to flow only from the bottom to the top. A fixed piston having a first large-diameter through-hole and a second large-diameter through-hole for liquid passage in the fixed portion; and a slidably mounted upper side of the fixed piston in the cylinder. A cylindrical portion extending along the cylinder center axis and slidably fitted to the outer peripheral surface of the shaft portion of the fixed piston, the upper wall of which is closed, and extending from the outer peripheral surface of the cylindrical portion and sliding on the inner peripheral surface of the cylinder. A small-diameter through-hole for liquid passage in the upper wall of the cylindrical portion; A movable piston having a third large-diameter through-hole for liquid passage therethrough; a piston rod having one end protruding outside the cylinder and the other end fixed to the upper wall of the movable piston; A spring for urging the piston and the movable piston in a separating direction; a bellows having a central portion fixed to an inner end of the cylinder of the piston rod and an outer end fixed to an inner wall of the cylinder; A diaphragm disposed between the lower wall of the cylinder and the fixed piston so as to cover each through-hole opening surface of the fixed piston, and wherein the inside of the cylinder between the bellows and the diaphragm is configured. A shock absorber characterized by comprising a liquid chamber hermetically containing a viscous liquid. 2. The shock absorber according to claim 1, wherein the bellows has a shape in which an annular thin plate portion between a center portion and an outer peripheral end portion is normally curved downward and swells downward. 3. The shock absorber according to claim 1, wherein the bellows has a ring-shaped thin plate portion between a center portion and an outer peripheral end portion. 4. The diaphragm has an outer peripheral end portion fixed to an inner peripheral wall of a cylinder, and a thin plate portion inside the outer peripheral end portion has a shape which is curved upward and bulges in a normal state. 3. The shock absorber according to any one of 3. 5. The shock absorber according to claim 1, wherein the diaphragm is formed of a substantially cylindrical bellows member having a bottom.