JP2004316894A - Diaphragm for shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly durable diaphragm to be used for a shock absorber with a vehicle levelling function, suppressing the permeation of gas through a gas chamber by restricting a reduction in thickness with the expansion or an enlarged diameter. <P>SOLUTION: A housing 16 of the shock absorber is sectioned into a gas chamber on the outer periphery side and an oil chamber on the inner periphery side. The diaphragm 26 whose diameter is enlarged or shrunk from the enlarged shape with operating oil put moved into or out of the oil chamber is previously formed in a shape midway between an originally set condition and a maximum diameter enlarged condition. It is set in the condition that the diameter is shrunk a preset amount from the shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diaphragm as a flexible partition that partitions an outer peripheral gas chamber and an inner peripheral oil chamber inside a housing of an automobile shock absorber.

  2. Description of the Related Art Conventionally, as one type of shock absorber that forms a main element of a vehicle suspension device, an outer peripheral gas chamber and an inner peripheral oil chamber formed in a housing are partitioned by a diaphragm, and hydraulic oil is supplied to the oil chamber. With the inflow or outflow from the oil chamber, the diaphragm is known to be deformed from the initial set state to the diameter or reduced from the expanded shape against the pressure of the gas chamber on the outer peripheral side. I have.

This diaphragm is mainly used for a shock absorber having a vehicle height adjusting function.
For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and Patent Literature 5 disclose a shock absorber having a vehicle height adjusting function using such a diaphragm.

The shock absorber provided with the vehicle height adjusting function includes a pump mechanism, and is stored in a reservoir chamber by a pumping action of the pump mechanism in accordance with the vertical movement of the piston rod accompanying the traveling of the vehicle, that is, the expansion and contraction operation of the shock absorber. Hydraulic oil is sucked into the pump chamber from the suction port of the pump chamber and discharged from the discharge port of the pump chamber. The hydraulic oil is supplied to the lower piston chamber and the oil chamber connected to the lower piston chamber, and the hydraulic oil flows into them and increases in pressure. Push up the position of the piston rod based on.
While repeating this operation, the vehicle height adjustment is performed by gradually pushing up the vehicle body that has been at the sinking position due to the loading of personnel or luggage.

  At that time, the diaphragm as a flexible partition that partitions the outer peripheral side gas chamber and the inner peripheral side oil chamber in the housing of the shock absorber moves from the initial set state, that is, the state at the time of assembling to the vehicle. The diameter expansion deformation and the diameter reduction deformation from the expanded shape are repeated.

  By the way, the size (radial dimension and axial dimension) of a shock absorber is required to be as small as possible from the viewpoint of mountability on a vehicle, and at the same time, the function as a shock absorber (ride comfort function and vehicle height adjustment) is required. From the viewpoint of function), there is a conflicting demand that the volume of the gas chamber on the outer peripheral side in the housing be as large as possible. Therefore, conventionally, the initial shape of the diaphragm has been reduced as much as possible, and The room volume is secured.

  In this case, when the diaphragm expands and deforms from the initial shape, that is, the shape in the initial set state, the distortion generated in the diaphragm increases, so the durability life of the diaphragm is shortened, and the diaphragm deforms and the expanded shape. There is a problem that the diaphragm is liable to crack or break due to fatigue early due to repetition of diameter reduction deformation of the diaphragm.

  Also, in the conventional diaphragm, since the amount of diameter expansion deformation due to the supply of hydraulic oil to the oil chamber on the inner peripheral side and the rise in pressure is large, the degree of reduction in the wall thickness due to the diameter expansion deformation is large. There is also a problem that the amount of gas permeated from the gas chamber to the oil chamber via the gas chamber increases.

The present invention has been made to solve such a problem.
Incidentally, the one disclosed in Patent Document 1 below aims at improving the durability of the diaphragm, but the solution is different from that of the present invention.
Patent Literatures 2, 3, 4, and 5 below disclose shock absorbers having a vehicle height adjustment function using a diaphragm, but do not particularly mention improvement in durability of the diaphragm.

JP-A-11-117977 JP-A-8-135716 JP-A-8-303521 JP-A-10-281205 JP 2000-135909 A

  In view of the above circumstances, the present invention provides a highly durable diaphragm that is suitably used for a shock absorber with a vehicle height adjusting function, and also suppresses a reduction in thickness due to expansion and expansion of gas. The purpose is to suppress gas permeation in the chamber.

  A diaphragm for a shock absorber according to the present invention devised to solve the above-described problem partitions a gas chamber on an outer peripheral side and an oil chamber on an inner peripheral side inside a housing of the shock absorber, and supplies hydraulic oil to the oil chamber. With a diaphragm for a shock absorber as a flexible partition wall, the diameter of which expands from the initially set state with the inflow or outflow from the oil chamber against the pressure of the gas chamber or decreases from the expanded shape. Then, the diaphragm is preliminarily formed into a shape in the middle from the shape in the initial setting state to the maximum expanded state, and is set in a shape reduced in diameter by a predetermined amount from the formed shape. It is characterized by having.

  A second aspect of the present invention is characterized in that, in the first aspect, a drum shape is formed in which both ends in the axial direction have a large diameter and an intermediate portion has a small diameter.

  A third aspect of the present invention is characterized in that, in the first aspect, it is formed in a straight cylindrical shape having a straight shape in the axial direction.

  A fourth aspect of the present invention is characterized in that, in the third aspect, the housing has a shape protruding radially outward.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the shock absorber has a vehicle height adjusting function.

Functions and effects of the invention

  As described above, according to the present invention, the diaphragm is not formed in the initial setting state, but is formed into a shape in the middle of reaching the maximum expanded state in advance, and the diameter is reduced by a predetermined amount from the formed shape. This is set in the shock absorber.

That is, conventionally, the molded shape of the diaphragm is the same as the shape in the initial set state, and therefore, the deformation at the time of the maximum diameter expansion is large, and the distortion generated in the diaphragm is also large, The durable life of the diaphragm was shortened by the large distortion, but in the present invention, the diaphragm is preliminarily formed into a shape in which the diameter is expanded to some extent from the shape in the initial set state, and the diameter is reduced from the formed shape. Since the diaphragm is set and used in this state, the deformation of the diaphragm does not increase even at the time of maximum diameter expansion.
That is, in the present invention, the diaphragm is used by being reduced in diameter or expanded in diameter around the molded shape, so that the distortion generated in the diaphragm is smaller than in the past, and the durability life is improved. Can be improved.

  Further, according to the present invention, even at the time of maximum diameter expansion, the thickness of the diaphragm is not so reduced, and therefore, the permeation of the gas in the gas chamber to the diaphragm can be effectively suppressed.

  In the present invention, when the deformation amount up to the maximum diameter expansion is set to 100% with respect to the shape at the time of setting, the shape of the diaphragm can be made to be approximately 50% of the deformed state. Alternatively, the molded shape can be determined in a shape within the range of 30 to 70% (however, an average value of deformation or distortion of each part of the diaphragm).

In the present invention, the diaphragm may have a drum shape in which both ends in the axial direction have a large diameter and an intermediate portion has a small diameter (claim 2).
Alternatively, the diaphragm may be formed in a straight cylindrical shape having a straight shape in the axial direction.
When the shape of the diaphragm is made to be such a straight cylindrical shape, as will be clarified later, the structure of the forming die for forming such a diaphragm can be simplified, and the forming becomes easier, and the diaphragm forming is facilitated. At times, the thickness can be equalized from one axial end to the other.

This straight cylindrical diaphragm is particularly suitable for a shock absorber in which the housing has a bulging shape radially outward (claim 4).
The present invention can be suitably applied particularly as a diaphragm of a shock absorber having a vehicle height adjusting function (claim 5).

Next, an embodiment in which the present invention is applied to a diaphragm of a shock absorber having a vehicle height adjusting function will be described in detail with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a shock absorber having a vehicle height adjusting function, 12 denotes a cylinder, and 14 denotes a piston rod protruding from the cylinder 12.

In this shock absorber 10, the lower end of the cylinder 12 is fixed to the wheel side, and the piston rod 14 is fixed to the vehicle body side, so that the input vibration from the wheel is absorbed by the damper action, and the vibration is transmitted to the vehicle body side. Prevent or suppress.
Reference numeral 16 denotes a housing formed at a lower portion of the cylinder 12. The housing 16 is configured such that an upper end and a lower end of a cylindrical wall 18 are closed by a partition wall 20 and an end cap 22.

Reference numeral 23 denotes a gas chamber (diaphragm-side gas chamber) formed on the outer peripheral side in the housing 16, and 24 denotes an oil chamber formed on the inner peripheral side. These oil chambers are provided on a rubber diaphragm 26 as a flexible partition. Is partitioned.
Here, nitrogen gas is sealed in the gas chamber 23 at a predetermined pressure, and the pressure is applied to the diaphragm 26 on the diameter reducing side.

2, the diaphragm 26 has a drum shape as a whole, and has a large-diameter portion 28 at both ends in the axial direction, a tapered portion 30 following the large-diameter portion 28, and a small-diameter portion at the middle portion in the axial direction. 32, and is attached and fixed to the housing 16 at a thick fixing portion 34 at the shaft end.
Reference numeral 36 denotes a hollow rod, which functions as a stopper for preventing the diaphragm 26 from being excessively deformed by the gas pressure when the gas is sealed in the gas chamber 23.

5 to 8 schematically show the operation of the shock absorber 10 at the time of adjusting the vehicle height, together with the configuration thereof.
In these figures, reference numeral 38 denotes an inner cylinder in which a piston 40 is slidably fitted, and the piston 40 defines a lower piston chamber 42 and an upper piston chamber 44.
Here, the lower piston chamber 42 communicates with the oil chamber 24 through a communication hole 43, and can communicate with a communication passage 48 described later through a communication hole 45.

On the outer peripheral side of the inner cylinder 38, an annular reservoir chamber 46 is formed at the lower part, and a gas chamber (piston side gas chamber) 47 is formed at the upper part. Nitrogen gas is sealed in the gas chamber 47 at a predetermined pressure. Hydraulic oil is stored in the reservoir chamber 46.
The reservoir chamber 46 can communicate with a pump chamber 52 formed inside the partition 50 inside the piston rod 14 through a communication passage 48.

The pump chamber 52 has a suction port 54, and the suction port 54 can be opened and closed by a check valve 56.
Here, the check valve 56 allows the inflow or suction of the hydraulic oil from the communication passage 48 into the pump chamber 52, while preventing the flow in the opposite direction.

A discharge port 58 is formed in the upper part of the pump chamber 52, and the discharge port 58 can be opened and closed by a check valve 60.
The check valve 60 allows only the discharge of the hydraulic oil from the pump chamber 52 and works to prevent the flow in the reverse direction.

The hydraulic oil flowing out of the pump chamber 52 through the discharge port 58 flows into the lower piston chamber 42 through the communication passage 62.
The pump chamber 52 can communicate with the lower piston chamber 42 through another communication passage 64.

  FIG. 5 shows a state where the shock absorber 10 is assembled to a vehicle. At this time, the piston rod 14 is in a state of protruding largely upward in the figure.

FIG. 6 (I) shows an empty state, that is, a state in which an empty vehicle weight is applied. At this time, the weight of the vehicle body is applied to the shock absorber 10, whereby the piston rod 14 is pushed downward in the figure. As a result, the pressure applied to the working fluid slightly increases.
In addition, the diaphragm 26 is slightly expanded and deformed against the gas pressure in the gas chamber 23.

  When the piston rod 14 is pushed downward in the drawing, the piston 40 moves downward in the inner cylinder 38 with the movement of hydraulic oil from the lower piston chamber 42 to the upper piston chamber 44.

In this state, as shown in FIG. 6 (II), when a load is applied to the vehicle body due to a person getting on the vehicle or a cargo being loaded, the load pushes the piston rod 14 further downward.
Also at this time, the piston 40 moves downward in the inner cylinder 38 with the movement of the hydraulic oil from the lower piston chamber 42 to the upper piston chamber 44. At this time, the hydraulic pressure of the working oil is slightly increased and hardly changes.

FIG. 7 shows a state during traveling divided into an extension step and a compression step (reduction step) of the shock absorber 10.
First, in the extension step (III), as the piston rod 14 moves upward, the hydraulic oil in the reservoir chamber 46 pushes the check valve 56 up against the spring through the communication passage 48 from the suction port 54 while pushing up the check valve 56 against the spring. It is sucked into the chamber 52.

The hydraulic oil sucked into the pump chamber 52 cannot be discharged from the discharge port 58 in this extending process, and is confined inside the pump chamber 52.
That is, in this extending step, the hydraulic oil stored in the reservoir chamber 46 is sucked into the pump chamber 52 through the communication path 48.

Next, when the push-down force acts on the piston rod 14 during traveling as shown in (IV), the hydraulic oil in the pump chamber 52 operates the check valve 60 as shown in (IV) in FIG. The water is discharged from the discharge port 58 while being pushed up against the urging force of the spring, and further flows into the oil chamber 24 through the communication passage 62 and the piston lower chamber 42 and the communication hole 43.
Then, based on the inflow and pressurization of the working oil into the oil chamber 24, the diaphragm 26 is deformed in diameter against the gas pressure in the gas chamber 23.

While the vehicle is running, the above operation is repeated, the pressure in the oil chamber 24 increases, the reaction force on the piston rod 14 increases, and the position of the piston rod 14 gradually increases.
Then, as shown in FIG. 8 (V), when the pump chamber 52 is in communication with the lower piston chamber 42 through the communication passage 64, the position adjustment of the piston rod 14, that is, the vehicle height adjustment is completed.

  That is, when viewed from the empty vehicle state of FIG. 6 (I), the hydraulic oil inside the reservoir chamber 46 is sucked out and pushed out into the oil chamber 24 by the pumping action of the pump mechanism to move the liquid, and the vehicle height is predetermined by the liquid movement. It is automatically adjusted to the height.

  When the load applied to the vehicle body is removed in the state where the vehicle height adjustment is completed and a person is lowered from the vehicle or removed from the vehicle, as shown in FIG. The pressure causes the diaphragm 26 to be greatly reduced in diameter and the hydraulic oil in the oil chamber 24 to be returned to the reservoir chamber 46 through the communication hole 43, the lower piston chamber 42, the communication hole 45, and the communication passage 48.

As described above, the diaphragm 26 repeats the diameter expansion deformation from the initial set state (the state at the time of assembly) and the diameter reduction deformation (return direction deformation) from the expanded state.
Conventionally, this diaphragm has the same shape at the time of molding (molding shape) as the shape at the time of setting, and assumes that the shape is the minimum deformation shape (the state where the deformation is substantially zero), and the diameter expansion deformation from now on And the diameter reduction deformation from the expanded shape was repeated.
That is, the conventional diaphragm is always used in a state where the diameter is expanded and deformed, and the expanded state is changed in accordance with the flow of hydraulic oil into and out of the oil chamber 24 and a change in oil pressure.

FIG. 3A shows a shape of a conventional diaphragm 26A, and FIG. 4I shows a state in which the diaphragm 26A is set on the shock absorber 10 (in a state at the time of assembly, in which the gas chamber 23 Represents nitrogen gas sealed at a predetermined pressure).
The shape of the diaphragm 26A at the time of this setting is substantially the same as the molded shape of FIG.

The diaphragm 26A is deformed in the radially expanding direction with this shape as a start shape. That is, it is deformed from the molded shape in the radially expanding direction.
FIG. 4 (III) 'shows a state in which the diaphragm 26A is most expanded and deformed, that is, a state in which the diaphragm 26A has been expanded and expanded, and (II)' shows an intermediate expanded shape.

  As can be seen from the changes in these figures, the diaphragm 26A is greatly deformed due to the diameter expansion deformation, and in some cases, the diaphragm 26A may undergo deformation similar to buckling with the diameter expansion. is there.

On the other hand, the diaphragm 26 of the present example has a shape at the time of molding as shown in FIG. 3B.
This molded shape is a shape exactly intermediate between the minimum shape and the maximum bulging shape in FIG. 4, that is, substantially the same shape as the shape shown in FIG. 4 (II).

  The shape of the diaphragm 26 in the initial set state is the same as that of the conventional diaphragm 26A, that is, the shape shown in FIG. 4 (I). Therefore, at this time, the entire diameter of the diaphragm 26 is smaller than that of the original formed shape. It is in the state of having done.

  The diaphragm 26 expands while compressing the gas chamber 23 with the inflow of the hydraulic oil into the oil chamber 24 and an increase in pressure, and passes through the shape shown in FIG. The shape changes to the maximum bulging shape shown in FIG.

That is, in the case of the conventional diaphragm 26A, only the diameter expansion is performed, but in the case of the diaphragm 26 of the present example, the diameter reduction deformation and the diameter expansion deformation are repeated with respect to the formed shape.
Therefore, as shown in FIG. 4 (III), the diaphragm 26 of the present example has a small degree of deformation, that is, a generated strain in the maximum expanded shape, and has a good shape even under the maximum expanded shape in FIG. 4 (III). Is kept.

FIG. 9 shows the measurement results of the distortion of each part generated at the time of diameter expansion of the conventional diaphragm 26A, and FIG. 10 shows the measurement results of the distortion of each part at the time of deformation of the diaphragm 26 of this example. It is a representation.
In these figures, the horizontal axis represents the position of the mark M applied in FIG. 4 in order from the left.

  As shown in FIG. 9, in the conventional diaphragm 26 </ b> A, distortion during molding and in the set state in FIG. 4 (I) is zero in each part, subsequent deformation is expansion deformation, and surface distortion is in each part. In each case, the maximum distortion is a high distortion of less than 80% on the plus side.

On the other hand, in the case of the diaphragm 26 of the present example, as is apparent from FIG. 10, the deformation of the diaphragm 26 becomes a deformation on the reduced diameter side and a deformation on the expanded diameter centering on the molded shape, and the distortion correspondingly changes. Distortion on the minus side and distortion on the plus side.
That is, the shape at the time of setting shown in FIG. 4 (I) is a diameter-reduced shape, that is, a deformation on the minus side as compared with the molded shape, and the maximum swelling shape of (III) is a diameter-expanded deformation, and the distortion is Both parts have positive distortion.

The maximum distortion is in the range of −40% to + 40% at the portion where the distortion is the largest, and the maximum distortion is smaller than that of the conventional diaphragm 26A.
As shown in FIG. 10, in this example, the molding shape is determined such that the distortion at the time of setting and the distortion at the time of maximum diameter expansion are in the range of −40% to + 40% for each part.

  As can be seen from FIG. 9, the largest distortion in the conventional diaphragm 26A is a portion where the shape is bent from the tapered portion to the small-diameter portion, and the distortion becomes smaller at the intermediate position in the axial direction. ing.

On the other hand, in the case of the diaphragm 26 of this example, such a phenomenon does not appear as can be seen from FIG.
This is because the difference in diameter between the large-diameter portion 28 at the shaft end and the small-diameter portion 32 at the intermediate portion in the axial direction during molding is smaller than that of the conventional diaphragm 26A.

As described above, in the case of the diaphragm 10 of the present embodiment, the generated distortion is smaller than that of the conventional diaphragm, and as a result, the durability life is greatly extended.
FIG. 11 shows the relationship between the strain and the number of endurance when repeatedly deformed. As is apparent from this figure, the diaphragm 26 of the present example has a longer durable life than the conventional diaphragm 26A. It can be 10 times or more.

In the case of the diaphragm 26 of the present embodiment as described above, distortion generated in the diaphragm 26 can be effectively reduced, and the durable life thereof can be extended.
Further, in this example, at the time of the maximum diameter expansion, the thickness of the diaphragm 26 does not become thinner than that of the conventional diaphragm 26A, so that the gas permeation from the gas chamber 23 to the oil chamber 24 via the diaphragm 26 is effectively performed. Can be suppressed.

FIG. 12 shows another embodiment of the present invention.
In this embodiment, the housing 16 of the shock absorber 10 has a bulging shape radially outward.
Specifically, the cylindrical wall 18 of the housing 16 has a bulged shape having a large diameter portion 18-1 and tapered portions 18-2 at both ends in the axial direction.
Correspondingly, in the present embodiment, the diaphragm 26 has a straight cylindrical shape that is straight in the axial direction in the shape at the time of molding.

FIG. 12 shows an intermediate state between the minimum diameter reducing state and the maximum diameter expanding state of the diaphragm 26. When the diaphragm 26 is filled with gas shown in FIG. The state is reduced from the state.
On the other hand, as shown in FIG. 13 (B), in the maximum diameter expanded state, it becomes a shape bulging radially outward from the straight cylindrical shape of FIG.

FIG. 14 shows a molding die of the straight diaphragm 26 in FIG.
In the figure, reference numeral 70 denotes a molding die. The molding die 70 has split dies 72 and 74 and a middle die 76 which are divided into two parts in the vertical direction in the figure.
Since the diaphragm 26 has a straight cylindrical shape with a straight shape in the axial direction, the molding die 70 can be of an integral structure as the middle die 76 as shown in FIG.

On the other hand, in the case of the diaphragm 26 having a drum shape, the mold 70A needs to have the middle mold 76A divided into two in the axial direction.
That is, it is necessary to configure the middle mold 76A by divided middle molds 76A-a and 76A-a in the axial direction.

  In the case of FIG. 14 (B), if the middle mold 76A has an integral structure, it is impossible to remove the diaphragm 26 which is a molded product after molding, so that the middle mold 76A is divided axially into middle molds 76A-a and 76A-a. It is necessary to adopt a two-part configuration.

On the other hand, in the case of the diaphragm 26 having a straight cylindrical shape, it is possible to satisfactorily remove the diaphragm 26 after molding even when the intermediate mold 76 having an integral structure is used.
Thus, in the case of FIG. 14B, there may be a slight difference in outer diameter between the split middle dies 76A-a and 76A-a. In this case, the thickness of the formed drum-shaped diaphragm 26 is reduced in the figure. The right and left parts are different.

  On the other hand, in the case of FIG. 14A, such a problem does not occur because the middle mold 76 has an integral structure, and the thickness of the diaphragm 26 can be made uniform from one end to the other end in the axial direction.

  Although the embodiment of the present invention has been described in detail, this is merely an example, and the present invention can be configured in variously modified forms without departing from the spirit thereof.

It is a figure showing a diaphragm which is one example of the present invention with a shock absorber. It is a figure which expands and shows the principal part of FIG. FIG. 2 is a diagram showing a molded shape of the diaphragm of FIG. 1 in comparison with a molded shape of a conventional diaphragm. FIG. 2 is a diagram illustrating a state of a shape change during use of the diaphragm of FIG. 1 in comparison with a conventional diaphragm. FIG. 2 is a diagram illustrating a state where a shock absorber including the diaphragm in FIG. 1 is assembled to a vehicle. FIG. 2 is an explanatory view schematically showing main steps of a vehicle height adjusting operation of the shock absorber in FIG. 1. FIG. 7 is an explanatory view schematically showing main steps shown in FIG. 6. FIG. 8 is an explanatory view schematically showing a main step following FIG. 7. FIG. 9 is a diagram illustrating the magnitude of distortion generated when a conventional diaphragm is deformed. FIG. 2 is a diagram illustrating the magnitude of distortion generated when the diaphragm of FIG. 1 is deformed. It is a figure showing the relationship between the magnitude of distortion and the number of times of endurance. It is a figure showing other embodiments of the present invention. It is a figure which shows the shape after deformation | transformation of the diaphragm in the same embodiment with a peripheral part. It is a figure which shows the structural example of the shaping | molding die of the diaphragm of the same embodiment with a comparative example.

Explanation of reference numerals

10 Shock Absorber 16 Housing 23 Gas Chamber 24 Oil Chamber 26 Diaphragm 28 Large Diameter 32 Small Diameter

Claims (5)

An outer peripheral gas chamber and an inner peripheral oil chamber are defined inside the housing of the shock absorber, and the gas chamber is changed from an initially set state with the inflow of hydraulic oil into or out of the oil chamber. A diaphragm for a shock absorber as a flexible partition that expands in diameter or reduces in diameter from its expanded shape against the pressure of
The diaphragm is previously formed into a shape in the middle from the shape in the initial setting state to the maximum expanded state, and is set in a shape reduced in diameter by a predetermined amount from the formed shape. A diaphragm for a shock absorber characterized by the following.   2. The diaphragm for a shock absorber according to claim 1, wherein both ends in the axial direction have a large diameter and a middle part has a small diameter.   The diaphragm for a shock absorber according to claim 1, wherein the diaphragm is formed in a straight cylindrical shape having a straight shape in the axial direction.   4. The diaphragm for a shock absorber according to claim 3, wherein the housing has a radially outwardly bulging shape.   The diaphragm for a shock absorber according to any one of claims 1 to 4, wherein the shock absorber has a vehicle height adjusting function.

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