JP7579213B2 - Seal member fixing structure, seal member fixing method, and shock absorber - Google Patents

Description

The present invention relates to a fixing structure for a sealing member, a fixing method for a sealing member, and a shock absorber.

Conventionally, shock absorbers are configured with, for example, a cylinder, a piston that is slidably inserted into the cylinder and divides the inside of the cylinder into two working chambers, and a rod with one end connected to the piston. When the shock absorber expands or contracts, it creates resistance to the flow of hydraulic oil between the working chambers, creating a pressure difference between the working chambers and generating a damping force to suppress the vibration of the object to be damped (see, for example, Patent Document 1).

This shock absorber also has a seal member that slides around the outer circumference of the rod, which prevents hydraulic oil in the cylinder from leaking around the rod, keeping the inside of the cylinder oil-tight.

Specifically, the sealing member comprises an annular insert metal, a rubber inner seal integrated with the inner periphery of the insert metal, and a rubber outer periphery seal integrated with the outer periphery of the insert metal. In the case of a twin-tube shock absorber as an example, the sealing member is stacked on the rod guide that supports the rod and inserted into the inner periphery of the outer tube that houses the cylinder, and then the end of the outer tube is crimped toward the inner periphery to secure it to the outer tube.

The sealing member fixed in this manner makes the inner seal slide against the outer circumference of the rod and the outer seal tightly contact the inner circumference of the outer tube, sealing the inside of the outer tube and preventing oil leakage from the cylinder and the outer tube.

The sealing member is obtained by insert molding, in which an insert metal is inserted into a mold that forms the inner and outer seals, and then a rubber material is filled into the mold to integrate the inner and outer seals with the insert metal. An adhesive must be applied to the insert metal before insert molding, but since it is troublesome to apply adhesive only to the areas where the inner and outer seals are to be installed, the entire insert metal is immersed in liquid adhesive and the adhesive is applied to the entire insert metal. Then, in the sealing member obtained after insert molding, a thin rubber film is formed on areas of the insert metal other than the areas where the inner and outer seals are to be installed.

The sealing member obtained in this way is fitted to the inner circumference of the outer tube, and then axial force is applied. The entire circumference of the end of the outer tube is pressed inward by roll crimping, and the sealing member is fixed to the outer tube by closely adhering to the outer circumference of the outer surface of the insert metal that faces outward.

When the seal member is fixed by crimping the outer tube in this way, as the end of the outer tube is folded inward, the rubber film attached to the outer end of the insert metal may be pushed out as thread-like rubber pieces toward the inner circumference as the end of the outer tube approaches, and the rubber pieces may break off and get between the inner seal part and the rod. If this happens, the sealing performance around the outer circumference of the rod will deteriorate, so a step is provided on the outer circumference of the outer end of the insert metal by forming an annular recess.

By providing a step in this way, after the tube end of the outer tube is crimped, a space is created to accommodate the rubber piece at the corner on the inner circumference side between the tube end and the step, preventing the rubber piece from migrating toward the inner circumference side of the insert metal and ensuring good sealing performance of the sealing member.

JP 2002-070920 A

When the end of the outer tube is crimped in this way to fix the seal member, the outer tube is bent at a right angle starting from the outer peripheral edge of the outer end of the insert metal and rides up onto the inner corner of the step. Therefore, as shown in Figure 4, the inner circumference of the crimped portion 100a formed by crimping the end of the outer tube 100 cannot adhere closely to the insert metal 101 near the outer circumference of the outer end of the insert metal 101, and peels off, creating a gap A.

If the crimped portion 100a of the outer tube 100 peels off from the outer periphery of the outer end of the insert metal 101 in this way, the strength of the crimped portion 100a of the outer tube 100 will decrease, and the sealing performance at the outer periphery of the sealing member may deteriorate.

The present invention aims to provide a fixing structure for a sealing member, a fixing method for a sealing member, and a shock absorber that can ensure good sealing performance without reducing the strength of the crimped portion.

In order to solve the above-mentioned problems, the fixing structure of the sealing member of the present invention is a fixing structure of the sealing member in which the sealing member, which has an annular insert metal and a sealing portion integrally formed with the insert metal and fits the outer periphery of the insert metal into the inner periphery of the tube to seal the inside of the tube, is fixed by crimping the tube end to the inner periphery side, and the insert metal has a step portion formed by an annular recess formed to the outermost periphery on the outer periphery side of the outer end facing outward from the tube, and a chamfered portion provided on the outer periphery of the step portion at the outer end, and the axial length of the chamfered portion is longer than the axial length of the step portion.

With this fixing structure for the sealing member, the axial length of the chamfered portion is longer than the axial length of the stepped portion. Therefore, when the end of the tube is crimped to form the crimped portion, the crimped portion deforms following the chamfered portion on the outer periphery of the outer end of the insert metal without being affected by the stepped portion, and the inner periphery of the insert metal at the starting point of the bend in the crimped portion adheres to the insert metal without peeling off.

In addition, in the sealing member fixing structure, the tube may be made of an aluminum alloy. With this sealing member fixing structure, the strength can be ensured even if the tube is made of an aluminum alloy, which is softer than steel, while the shock absorber or the like to which the sealing member fixing structure is applied can be made lighter.

Furthermore, in order to solve the above-mentioned problems, the method of fixing a sealing member of the present invention is a method of fixing a sealing member that has an annular insert metal and a sealing portion integrally formed with the insert metal, and that fits the outer periphery of the insert metal to the inner periphery of the tube to seal the inside of the tube, by crimping the tube end toward the inner periphery, and is a method of fixing a sealing member in which a sealing member having a step portion formed on the outer end of the insert metal facing outward from the tube to the outermost periphery and a chamfered portion on the outer periphery of the step portion having an axial length longer than the axial length of the step portion is inserted into the tube, and the tube end is crimped toward the inner periphery to fix the sealing member to the tube.

With this method of fixing the sealing member, the axial length of the chamfered portion is longer than the axial length of the stepped portion, so when the end of the tube is crimped to form the crimped portion, the crimped portion deforms to follow the chamfered portion on the outer periphery of the outer end of the insert metal without being affected by the stepped portion, and the inner periphery of the insert metal at the starting point of the bend in the crimped portion adheres to the insert metal without peeling off.

In order to solve the above-mentioned problems, the shock absorber of the present invention includes a rod that is inserted axially movably into the tube, a ring-shaped rod guide that is fitted to the inner circumference of the tube and slides against the outer circumference of the rod to guide the movement of the rod, a ring-shaped insert metal that is fitted to the inner circumference of the tube, an inner circumference seal portion that is integrally provided on the inner circumference side of the insert metal and slides against the outer circumference of the rod, and an outer circumference seal portion that is integrally provided on the outer circumference side of the insert metal and abuts against the inner circumference of the tube, and a seal member that abuts the insert metal against the outer end of the rod guide that faces outward from the tube, and seals the inside of the tube, and the insert metal has a step portion provided by a ring-shaped recess formed on the outer circumference side of the outer end that faces outward from the tube to the outermost circumference, and a chamfered portion provided on the outer circumference of the step portion at the outer end, the axial length of the chamfered portion is longer than the axial length of the step portion, and the seal member is fixed to the tube by crimping the end of the tube toward the inner circumference.

In a shock absorber configured in this way, the axial length of the chamfered portion is longer than the axial length of the stepped portion, so when the end of the tube is crimped to form the crimped portion, the crimped portion deforms following the chamfered portion on the outer periphery of the outer end of the insert metal without being affected by the stepped portion, and the inner periphery of the insert metal at the starting point of the bend in the crimped portion adheres to the insert metal without peeling off.

The sealing member fixing structure, sealing member fixing method, and shock absorber of the present invention can ensure good sealing performance without reducing the strength of the crimped portion.

1 is a vertical cross-sectional view of a shock absorber to which a sealing member fixing structure according to an embodiment of the present invention is applied; 1 is a partially enlarged vertical cross-sectional view of a shock absorber to which a fixing structure for a seal member according to an embodiment of the present invention is applied; 5A to 5C are diagrams illustrating a method for fixing a seal member in one embodiment. FIG. 11 is an enlarged vertical cross-sectional view of a conventional sealing member fixing structure.

The present invention will be described below with reference to the drawings. In one embodiment, the fixing structure of the seal member 1 is applied to a shock absorber D as shown in FIG. 1, and the seal member 1 slides against the outer periphery of the rod 3 that enters and exits the cylinder 2, which serves as a tube in the shock absorber D, and abuts against the inner periphery of the cylinder 2, sealing the inside of the cylinder 2.

Each part will be described in detail below. First, the structure of shock absorber D will be described. In this case, shock absorber D is configured as a single-tube shock absorber, and includes a cylinder 2 as a tube, a rod 3 inserted into the cylinder 2 so as to be movable in the axial direction, a ring-shaped rod guide 4 that is fitted into the inner circumference of the cylinder 2 and slides against the outer circumference of the rod 3 to guide the movement of the rod 3, and a ring-shaped seal member 1 that is fitted into the inner circumference of the cylinder 2 and is layered on the side of the rod guide 4 opposite the cylinder.

In addition to the above configuration, the shock absorber D is also configured with a free piston 5 that is slidably inserted into the cylinder 2 and divides the cylinder 2 into an air chamber G filled with gas and a liquid chamber L filled with liquid, a piston 6 that is slidably inserted into the cylinder 2 and divides the liquid chamber L in the cylinder 2 into an extension side chamber R1 and a compression side chamber R2, a passage 7 provided in the piston 6 that connects the extension side chamber R1 and the compression side chamber R2, and a damping valve 8 that provides resistance to the flow of liquid passing through the passage 7.

In the shock absorber D of this embodiment, the cylinder 2 is a tube made of an aluminum alloy, the lower end of which is closed in FIG. 1 to form a bottomed tube, and the upper tube end in FIG. 1 is crimped to secure the seal member 1 and rod guide 4 housed in the cylinder 2. If the cylinder 2 is a tube with an open bottom, the opening at the bottom of the cylinder 2 can be closed with a cap.

The rod guide 4 is annular and includes a recess 4b on the inner periphery of the outer end 4a facing outward from the cylinder 2, which is the upper end in FIG. 1, an annular recess 4c provided around the entire outer periphery of the outer end 4a, which is the upper end in FIG. 1, and a cylindrical bush 4d provided on the inner periphery and sliding against the outer periphery of the rod 3. The rod guide 4 is fitted to the inner periphery of the upper end of the cylinder 2 in FIG. 1 in a state in which downward movement in FIG. 1 is restricted by a snap ring 9 fitted to the inner periphery of the cylinder 2, and closes the upper end opening of the cylinder 2. The rod 3 is inserted into the inner periphery of the rod guide 4, and the bush 4d on the inner periphery of the cylinder slides against the outer periphery of the rod 3 to guide the axial movement of the rod 3, which is the up-down direction in FIG. 1.

Next, the seal member 1, which is disposed above the rod guide 4 in FIG. 1, includes an annular insert metal 11, an annular inner seal 12 integrally provided on the inner periphery of the insert metal 11, and an annular outer seal portion 13 integrally provided on the outer periphery of the insert metal 11, as shown in FIGS. 1 and 2. The seal member 1 is fitted to the inner periphery of the cylinder 2 while abutting against the outer end 4a of the rod guide 4, which is the side opposite the cylinder, and the rod 3 is inserted into the inner periphery, so that the inner seal 12 is in sliding contact with the outer periphery of the rod 3 and the outer seal 13 is in abutment with the inner periphery of the cylinder 2, sealing the inside of the cylinder 2.

The insert metal 11 is an annular plate with a roughly rectangular cross section, and includes a stepped portion 11b formed as an annular recess on the outer periphery of the outer end 11a, which is the end face (upper end face in FIG. 1) that faces outward from the cylinder 2, all the way to the outermost periphery, and a chamfered portion 11c formed on the outer periphery of the stepped portion 11a, which is the outermost periphery of the outer end 11a, all the way around. The insert metal 11 is fitted into the inner periphery of the cylinder 2 with the outer end 11a on the opposite side to the cylinder facing the atmosphere.

The step portion 11b is formed by providing an annular recess from the middle of the outer circumference of the outer end 11a of the insert metal 11 to the outermost circumference, and the outermost circumference of the step portion 11b is also the outermost circumference of the outer end 11a of the insert metal 11. In this embodiment, the chamfered portion 11c is formed by C-chamfering the outermost circumference of the outer end of the insert metal 11, but it may be formed by R-chamfering. In addition, the axial length L1, which is the vertical length of the chamfered portion 11c in FIG. 1, is set to be longer than the axial length L2, which is the vertical length of the step portion 11b in FIG. 1. In other words, as shown in FIG. 2, if the axial length of the chamfered portion 11c is L1 and the axial length of the step portion 11b is L2, the dimensions of the chamfered portion 11c and the step portion 11b are set so as to satisfy L1>L2.

The inner seal portion 12 is annular and is integrated with the insert metal 11 by insert molding a rubber material around the entire inner circumference of the insert metal 11. It has a first lip 12a that slides against the outer circumference of the rod 3 to mainly prevent liquid from leaking from the cylinder 2, and a second lip 12b that is provided on the opposite side of the first lip 12a and slides against the outer circumference of the rod 3 to mainly prevent water, dust, etc. from entering the cylinder 2. When the seal member 1 is stacked on the outer end 4a of the rod guide 4 and inserted into the cylinder 2, the first lip 12a of the inner seal 12 is accommodated in the recess 4b provided on the inner circumference of the rod guide 4. When the seal member 1 is inserted into the cylinder 2, the first lip 12a and the second lip 12b of the inner seal 12 slide against the outer circumference of the rod 3 to seal the periphery of the rod 3.

When the sealing member 1 is laminated on the outer end 4a of the rod guide 4 and inserted into the cylinder 2, the outer periphery seal 13 penetrates into the annular gap between the cylinder 2 and the recess 4c provided on the outer periphery of the rod guide 4, and adheres closely to both the rod guide 4 and the cylinder 2 to seal between the cylinder 2 and the rod guide 4.

The sealing member 1 thus constructed is inserted into the cylinder 2 together with the rod guide 4, and is fixed to the cylinder 2 by being clamped together with the rod guide 4 by the snap ring 9 and the crimped portion 2a, which is formed by rolling the upper tube end of the cylinder 2 in FIG. 1 and bending it inward.

The free piston 5 is slidably inserted into the cylinder 2 and divides the cylinder 2 into an air chamber G and a liquid chamber L. When the free piston 5 moves axially relative to the cylinder 2, it expands one of the air chamber G and the liquid chamber L and shrinks the other. The piston 6 is slidably inserted into the cylinder 2 and is connected to the tip of the rod 3, and divides the liquid chamber L in the cylinder 2 into an extension side chamber R1 and a compression side chamber R2.

The piston 6 is provided with a passage 7 that connects the extension side chamber R1 and the compression side chamber R2, and a damping valve 8 that provides resistance to the flow of liquid passing through the passage 7. In this embodiment, the damping valve 8 is a valve that allows the liquid to flow in both directions, from the extension side chamber R1 to the compression side chamber R2 and from the compression side chamber R2 to the extension side chamber R1. However, when multiple passages are provided in the piston 6, a one-way valve that allows only the flow of liquid from the extension side chamber R1 to the compression side chamber R2 may be provided in a part of the passage, and a one-way valve that allows only the flow of liquid from the compression side chamber R2 to the extension side chamber R1 may be provided in the remaining passages. In addition to hydraulic oil, the liquid filled in the cylinder 2 can be water, an aqueous solution, an electrorheological fluid, a magnetorheological fluid, or any other liquid that is applicable to a shock absorber. When the liquid is an electrorheological fluid or a magnetorheological fluid, a damping force generating means that applies an electric field or a magnetic field to the passage 7 may be provided instead of the damping valve 8. The gas filled in the air chamber G may be air, but it is preferable to use an inert gas such as nitrogen.

As mentioned above, the shock absorber D is a single-tube shock absorber, and when it expands, the damping valve 8 provides resistance to the flow of liquid moving from the compression side chamber R1 at the top in FIG. 1, which is compressed, through the passage 7 provided in the piston 6 to the expanded compression side chamber R2 at the bottom in FIG. 1, generating a damping force on the expansion side. Conversely, when the shock absorber D contracts, the damping valve 8 provides resistance to the flow of liquid moving from the compression side chamber R2 at the bottom in FIG. 1, which is compressed, through the passage 7 provided in the piston 6 to the expanded expansion side chamber R1 at the top in FIG. 1, generating a damping force on the compression side.

In addition, in this shock absorber D, the volume of the rod 3 entering or exiting the cylinder 2 during the extension/retraction stroke is compensated for by the air chamber G expanding or contracting.

The shock absorber D described above is just one example, and may be a twin-tube shock absorber in which an outer tube is provided around the outer periphery of the cylinder 2, and a reservoir is provided in the annular gap between the cylinder 2 and the outer tube to compensate for the volume of the rod 3 moving in and out of the cylinder 2, or a double-rod shock absorber in which the rod 3 penetrates the piston 6 and protrudes to the outside from both ends of the cylinder 2. In this way, when shock absorber D is a twin-tube shock absorber, the outer tube is used as a tube, and the sealing member 1 is fixed by crimping the tube end of the outer tube, and the inside of the outer tube is sealed with the sealing member 1.

The shock absorber D configured as above is assembled as follows. First, as described above, the insert metal 11 of the seal member 1 is provided with a step 11b at the outer end 11a on the opposite side to the cylinder, and a chamfered portion 11c. Specifically, the outer periphery of the outer end 11a of the insert metal 11 is cut to form the step 11b, and then the outermost periphery of the outer end 11a of the insert metal 11 is cut to perform C-chamfering to form the chamfered portion 11c. The order in which the step 11b and the chamfered portion 11c are formed on the insert metal 11 may be reversed. When the insert metal 11 is molded by pressing in which the insert metal 11 is punched out from a plate material, the step 11b and the chamfered portion 11c may be punched out with a die and molded at the same time. In addition, when molding the insert metal 11 by sintering or the like, the step portion 11b and the chamfered portion 11c may be molded at the same time as the sintering molding by using a mold capable of forming the step portion 11b and the chamfered portion 11c.

Once the insert metal 11 is obtained, an adhesive is applied to the insert metal 11, and then the insert metal 11 is inserted into a mold (not shown) that forms the inner seal portion 12 and the outer seal portion 13, and a rubber material is injected into the mold and baked. Then, the inner seal portion 12 and the outer seal portion 13, both made of rubber, are integrated into the insert metal 11 by insert molding, and the seal member 1 is obtained.

Then, the free piston 5 is inserted into the cylinder 2, and the piston 6 attached to the rod 3 is inserted into the cylinder 2, after which the snap ring 9 is attached to the cylinder 2.

Then, the sealing member 1 obtained as described above is inserted into the cylinder 2 after inserting the rod guide 4 into the cylinder 2 until the rod guide 4 abuts against the snap ring 9 previously attached to the inner circumference of the cylinder 2, as shown in FIG. 3.

Specifically, the seal member 1 is inserted into the cylinder 2 by fitting the outer periphery of the insert metal 11 into the inner periphery of the cylinder 2 and abutting the inner surface 11d of the insert metal 11 facing the cylinder side against the outer end 4a of the rod guide 4. Note that the seal member 1 may be inserted into the cylinder 2 together with the rod guide 4 in a state where it is overlapped on the rod guide 4.

When the seal member 1 is inserted into the cylinder 2 together with the rod guide 4, the seal member 1 penetrates a specified length from the top end of the cylinder 2, and the tube end portion of the cylinder 2 protrudes in the axial direction beyond the outer end 11a of the insert metal 11.

In this way, with the sealing member 1 inserted inside the cylinder 2, the entire circumference or several places of the end of the tube of the cylinder 2 are slightly bent toward the inner circumference to perform temporary crimping.

The seal member 1 is then temporarily fixed to the cylinder 2 by the tube end that has been bent toward the inner circumference of the cylinder 2 by the temporary crimping. After that, while applying an axial force toward the rod guide 4 to the seal member 1, the entire circumference of the tube end of the cylinder 2 is crimped from the outer periphery, so that the tube end is bent toward the inside of the cylinder 2 to form the crimped portion 2a, as shown by the dashed line in Figure 3, and the seal member 1 and rod guide 4 are sandwiched between the crimped portion 2a and the snap ring 9 and fixed to the cylinder 2.

Here, as shown in FIG. 2, the crimped portion 2a of the cylinder 2 is bent and deformed starting from the chamfered portion 11c on the outer circumference of the outer end 11a of the insert metal 11. The tip of the crimped portion 2a then rides up onto the corner 11e of the inner wall of the step portion 11b, which is formed on the inner circumference side of the chamfered portion 11c of the outer circumference surface 11a of the insert metal 11, and reaches the inner circumference side. In this way, the crimped portion 2a formed by crimping the tube end of the cylinder 2 rides up onto the corner 11e of the inner circumference of the step portion 11b, but since the axial length L1 of the chamfered portion 11c is longer than the axial length L2 of the step portion 11b, it deforms following the chamfered portion 11c on the outer circumference of the outer end 11a of the insert metal 11 without being affected by the step portion 11b, and therefore adheres to the upper surface of the step portion 11b in FIG. 2 without peeling.

As the crimping process of the tube end of the cylinder 2 progresses and the tube end is gradually folded inward, the rubber film formed on the upper surface of the step portion 11b of the insert metal 11 is pushed out toward the inner circumference, generating thread-like rubber pieces. However, after the crimping process, a gap S that accommodates the rubber pieces is formed in the corner between the crimped portion 2a and the inner wall surface of the step portion 11b, trapping the rubber pieces and restricting their movement toward the inner circumference of the insert metal 11, so the sealing properties of the seal member 1 are not impaired.

As described above, the fixing structure of the seal member 1 in this embodiment has an annular insert metal 11, an inner seal portion (seal portion) 12 and an outer seal portion (seal portion) 13 integrally formed with the insert metal 11, and the seal member 1 that seals the inside of the cylinder (tube) 2 by fitting the outer periphery of the insert metal 11 to the inner periphery of the cylinder (tube) 2 is fixed by crimping the tube end of the cylinder (tube) 2 to the inner periphery side, and the insert metal 11 has a stepped portion 11b provided by an annular recess formed to the outermost periphery on the outer side of the outer end 11a facing outward from the cylinder (tube) 2, and a chamfered portion 11c provided on the outer periphery of the stepped portion 11b at the outer end 11a, and the axial length L1 of the chamfered portion 11c is longer than the axial length L2 of the stepped portion 11b.

According to the fixing structure of the seal member 1 configured in this manner, the axial length L1 of the chamfered portion 11c is longer than the axial length L2 of the step portion 11b. Therefore, when the end of the cylinder (tube) 2 is crimped to form the crimped portion 2a, the crimped portion 2a is deformed following the chamfered portion 11c on the outer periphery of the outer end 11a of the insert metal 11 without being affected by the step portion 11b, and the inner periphery of the starting point of the bend of the crimped portion 2a at the outer periphery of the insert metal 11 adheres to the insert metal 11 without peeling. Therefore, according to the fixing structure of the seal member 1 of this embodiment, the crimped portion 2a of the cylinder (tube) 2 adheres to the insert metal 11 without peeling, so that the strength of the crimped portion 2a is not reduced and good sealing properties of the seal member 1 can be ensured.

In addition, in the fixing structure of the seal member 1 of this embodiment, even if the cylinder (tube) 2 is made of an aluminum alloy, which is softer than when it is made of steel, the strength is guaranteed because the crimped portion 2a formed by crimping the tube end of the cylinder 2 adheres closely to the outer periphery of the outer end 11a of the insert metal 11, as described above. Therefore, according to the fixing structure of the seal member 1 of this embodiment, even if the cylinder (tube) 2 is made of an aluminum alloy, which is softer than steel, the strength is ensured, while the shock absorber D to which the fixing structure of the seal member 1 is applied can be made lighter.

Furthermore, the method of fixing the seal member 1 in this embodiment is a method of fixing the seal member 1, which has an annular insert metal 11 and an inner seal portion (seal portion) 12 and an outer seal portion (seal portion) 13 integrally formed with the insert metal 11, and which fits the outer periphery of the insert metal 11 to the inner periphery of the cylinder (tube) 2 to seal the inside of the cylinder (tube) 2, by crimping the tube end of the cylinder (tube) 2 to the inner periphery. The seal member 1 is provided with a step portion 11b formed on the outer periphery of the outer end 11a of the insert metal 11 facing outward from the cylinder (tube) 2 to the outermost periphery, and a chamfered portion 11c having an axial length L1 longer than the axial length L2 of the step portion 11b on the outer periphery of the step portion 11b, and is inserted into the cylinder (tube) 2, and the tube end of the cylinder (tube) 2 is crimped to the inner periphery to fix the seal member 1 to the cylinder (tube) 2.

According to the fixing method of the seal member 1 configured in this manner, since the axial length L1 of the chamfered portion 11c is longer than the axial length L2 of the step portion 11b, when the end of the cylinder (tube) 2 is crimped to form the crimped portion 2a, the crimped portion 2a deforms following the chamfered portion 11c on the outer periphery of the outer end 11a of the insert metal 11 without being affected by the step portion 11b, and the inner periphery of the starting point of the bend of the crimped portion 2a at the outer periphery of the insert metal 11 adheres to the insert metal 11 without peeling. Therefore, according to the fixing method of the seal member 1 of this embodiment, the crimped portion 2a of the cylinder (tube) 2 adheres to the insert metal 11 without peeling, so that there is no decrease in strength at the crimped portion 2a, and good sealing properties of the seal member 1 can be ensured.

Furthermore, the shock absorber D in this embodiment has a rod 3 inserted into the cylinder (tube) 2 so as to be movable in the axial direction, a ring-shaped rod guide 4 that is fitted to the inner circumference of the cylinder (tube) 2 and slides against the outer circumference of the rod 3 to guide the movement of the rod 3, a ring-shaped insert metal 11 that is fitted to the inner circumference of the cylinder (tube) 2, an inner circumference seal portion 12 that is integrally provided on the inner circumference side of the insert metal 11 and slides against the outer circumference of the rod 3, and an outer circumference seal portion 13 that is integrally provided on the outer circumference side of the insert metal 11 and abuts against the inner circumference of the cylinder (tube) 2. The seal member 1 seals the inside of the cylinder (tube) 2 by abutting the insert metal 11 against the outer end 4a facing outward from the cylinder (tube) 2, and the insert metal 11 has a step 11b provided by an annular recess formed on the outer periphery of the outer end 11a facing outward from the cylinder (tube) 2 and a chamfered portion 11c provided on the outer periphery of the step 11b at the outer end 11a, the axial length L1 of the chamfered portion 11c is longer than the axial length L1 of the step 11b, and the seal member 1 is fixed to the cylinder (tube) 2 by crimping the tube end of the cylinder (tube) 2 toward the inner periphery.

According to the shock absorber D configured in this manner, the axial length L1 of the chamfered portion 11c is longer than the axial length L2 of the stepped portion 11b. Therefore, when the end of the cylinder (tube) 2 is crimped to form the crimped portion 2a, the crimped portion 2a is deformed following the chamfered portion 11c on the outer periphery of the outer end 11a of the insert metal 11 without being affected by the stepped portion 11b, and the inner periphery of the starting point of the bend of the crimped portion 2a at the outer periphery of the insert metal 11 adheres to the insert metal 11 without peeling. Therefore, according to the shock absorber D of this embodiment, the crimped portion 2a of the cylinder (tube) 2 adheres to the insert metal 11 without peeling, so there is no decrease in the strength of the crimped portion 2a, and the seal member 1 maintains good sealing properties, so that a stable damping force can be exerted over a long period of time.

As mentioned above, the shock absorber D of this embodiment is a single-tube shock absorber, so the cylinder 2 is a tube, but in the case of a double-tube shock absorber, the outer tube that covers the outer periphery of the cylinder and forms a reservoir between the cylinder and the outer tube may be a tube. In addition, the outer end 11a of the insert metal 11 in the seal member 1 only needs to have a step portion 11b and a chamfered portion 11c, and the seal portion in the seal member 1 only needs to be able to seal the inside of the tube, so the installation location, shape, and number of seal portions relative to the insert metal 11 can be appropriately designed. In addition, the fixing structure and fixing method of the seal member 1 in this invention can be used for fluid pressure actuators and other fluid pressure devices other than the shock absorber D. In addition, in the description of the shock absorber D, the working fluid is described as a liquid, but only gas may be used as the working fluid, and the working fluid in the fluid pressure actuators and other fluid pressure devices to which the fixing structure and fixing method of the seal member 1 are applied is not limited to a liquid.

Although the preferred embodiment of the present invention has been described in detail above, modifications, variations, and changes are possible without departing from the scope of the claims.

1: sealing member, 2: cylinder (tube), 3: rod, 4: rod guide, 4a: outer end of rod guide, 11: insert metal, 11a: outer end, 11b: step, 11c: chamfered portion, 12: inner seal portion (seal portion), 13: outer seal portion (seal portion), D: shock absorber, L1: axial length of chamfered portion, L2: axial length of step portion,

Claims (4)

A sealing member fixing structure in which a sealing member having an annular insert metal and a sealing portion integrally formed with the insert metal, the sealing member sealing the inside of the tube by fitting an outer periphery of the insert metal into an inner periphery of the tube, is fixed by crimping a tube end of the tube toward the inner periphery,
the insert metal has a step portion formed by an annular recess formed to the outermost periphery on the outer periphery side of an outer end facing outward from the tube, and a chamfered portion provided on the outer periphery of the step portion at the outer end,
A structure for fixing a seal member, wherein an axial length of the chamfered portion is longer than an axial length of the stepped portion. The structure for fixing a seal member according to claim 1, wherein the tube is made of an aluminum alloy. A method for fixing a seal member, the method comprising: fixing a seal member having an annular insert metal and a seal portion integrally formed with the insert metal, the seal member being adapted to fit an outer periphery of the insert metal into an inner periphery of a tube to seal the inside of the tube, by crimping an end of the tube toward the inner periphery, the method comprising the steps of:
a seal member is inserted into the tube, the seal member having a stepped portion formed on an outer end of the insert metal facing outward from the tube, the stepped portion being formed on an outer periphery of the stepped portion and a chamfered portion having an axial length longer than an axial length of the stepped portion on an outer periphery of the stepped portion;
a tube end of the tube being crimped toward an inner periphery to fix the seal member to the tube. A rod that is inserted into the tube so as to be movable in the axial direction;
a rod guide that is annular and fitted to an inner periphery of the tube and that slides against an outer periphery of the rod to guide the movement of the rod;
a seal member having an annular insert metal fitted onto the inner periphery of the tube, an inner periphery seal portion integrally provided on the inner periphery side of the insert metal and in sliding contact with the outer periphery of the rod, and an outer periphery seal portion integrally provided on the outer periphery side of the insert metal and in contact with the inner periphery of the tube, the insert metal being abutted against an outer end of the rod guide facing outward with respect to the tube to seal the inside of the tube,
the insert metal has a step portion formed by an annular recess formed on an outer periphery side of an outer end facing outward from the tube up to the outermost periphery, and a chamfered portion provided on the outer periphery of the step portion at the outer end,
an axial length of the chamfered portion is longer than an axial length of the stepped portion;
The shock absorber, wherein the sealing member is fixed to the tube by crimping an end of the tube toward an inner periphery.

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