JP6689332B2 - Bump stopper, shock absorber, and bump stopper manufacturing method - Google Patents

Description

  The present invention relates to a bump stopper, a shock absorber, and a bump stopper manufacturing method.

  Conventionally, a shock absorber includes an outer tube and a rod that is inserted into and retractable from the outer tube, a bump stopper rubber provided on the rod side, and a bump stopper provided on the end of the outer tube.

  In such a shock absorber, the bump stopper rubber collides with the bump stopper and is compressed at the time of the most contraction when the rod enters the outer tube most, and the bump stopper rubber exerts elastic force. The shock is alleviated.

  The bump stopper includes a tubular portion having a perfect circular cross section that is fitted to the outer periphery of the outer tube, and an annular stopper portion that is provided at the top of the tubular portion and that faces the bump cushion rubber and allows the rod to be inserted. It is provided and is fitted to the outer circumference of the end portion of the outer tube.

  More specifically, the bump stopper has a plurality of ribs arranged side by side in the circumferential direction on the inner circumference of the tubular portion.The ribs are pressed against the outer circumference of the outer tube to tighten the outer tube and fix it to the outer tube. (For example, see Patent Document 1). That is, the conventional bump stopper is fixed to the outer tube by press fitting, which prevents the bump stopper from falling off.

  Therefore, if the diameter of the cylinder is reduced and the tightening force is increased, the bump stopper can be securely fixed to the outer tube.However, when the bump stopper is pressed into the outer circumference of the end of the outer tube, There is a possibility that a large stress will be applied to the joint portion of and the bump stopper will be broken. Therefore, in the conventional bump stopper, the annular groove is provided on the outer peripheral portion of the inner surface of the top portion to relieve the stress concentration on the joint portion.

JP, 2007-57088, A

  Such a conventional bump stopper is integrally molded of synthetic resin, and as shown in FIG. 6, the synthetic resin is injected into the mold 100 for molding the bump stopper from a position corresponding to the inner circumference of the top of the mold 100. And then molded.

  Since the bump stopper is provided with a plurality of ribs on the tubular portion, the gap of the portion corresponding to the tubular portion in the mold 100 for forming the bump stopper has a wide portion corresponding to the rib when viewed in the circumferential direction. The area corresponding to other areas becomes narrower.

  When injecting the synthetic resin into the mold 100, the synthetic resin quickly enters the wide part of the mold 100, but it takes time to enter the narrow part. Therefore, in the narrow portion in the mold 100, the synthetic resin is cooled, and the synthetic resin can also flow in from the wide portion, so that the portion of the molded bump stopper having the thin wall portion of the cylindrical portion is thin. A weld line will be generated at.

  The place where the weld line is generated becomes weaker in strength, so if the weld line occurs in the thin part of the bump stopper cylinder, the bump stopper will break when the bump stopper is pressed into the outer tube. there is a possibility.

  Therefore, the present invention provides a bump stopper that can prevent cracking when the outer tube is attached to the outer periphery of the end portion, and a shock absorber provided with the bump stopper. It is an object of the present invention to provide a bump stopper manufacturing method capable of preventing cracking prevention.

  In order to solve the above-mentioned object, the bump stopper of the present invention has an annular top portion, a tubular portion arranged on the outer periphery of the top portion, an annular portion that connects the top portion and the tubular portion and surrounds the outer periphery of the top portion inside. It is integrally molded of synthetic resin with a connecting portion having a groove, and is configured such that the wall thickness from the bottom of the annular groove in the connecting portion to the outside of the connecting portion is smaller than the minimum wall thickness of the top portion. .

  The bump stopper configured as described above can prevent a weld line from being generated in a thin-walled portion other than the rib of the tubular portion when the resin is molded by the mold. In addition, since the bump stopper configured as described above can prevent the weld line from being generated in the tubular portion, there is a concern that the tubular portion 3 will be cracked even if the tightness of the tubular portion to the outer tube is increased. Absent. Furthermore, since the connection part has an annular groove, the connection part can be flexibly deformed when the cylinder part is press-fitted to the outer circumference of the outer tube, so even if the tightening force of the cylinder part on the outer tube is increased There is no need to worry about cracks in the parts.

  Further, the thickness of the bump stopper from the bottom of the annular groove to the outside of the connecting portion may be equal to or less than the minimum thickness of the tubular portion. According to the bump stopper configured as described above, it is possible to effectively suppress the generation of a weld line in the tubular portion, and thus the strength of the tubular portion is improved.

  Further, the bump stopper may include a plurality of protrusions whose tops are arranged inward along the circumferential direction, and a tubular portion may be provided with a plurality of ribs arranged inside along the circumferential direction. Since the bump stopper thus configured is provided with the protrusion and the rib, the strength of the bump stopper is improved, and even if the amount of tightening is increased, the parts other than the rib of the tubular portion are easily deformed, so that the press-fitting work is facilitated. .

  Further, the bump stopper may be provided at a position where the projection and the rib overlap each other in the radial direction, and in this case, water, dust and the like that have entered the annular groove a are quickly discharged.

  Furthermore, the shock absorber of the present invention has an outer tube and a rod that moves in and out of the outer tube, and a shock absorber body that exerts a damping force when the rod moves in and out of the outer tube; and the bump stopper. Is equipped with. According to the shock absorber thus configured, there is no fear of cracking even if the bump stopper is press-fitted into the outer circumference of the outer tube.

  Further, the method for manufacturing a bump stopper according to the present invention includes an annular top portion, a tubular portion arranged on the outer periphery of the top portion, an annular groove that connects the top portion and the tubular portion and is provided inside along the outer periphery of the top portion. And a connecting part having a connecting part having a wall thickness from the bottom of the annular groove in the connecting part to the outside of the connecting part is smaller than the minimum wall thickness at the top part. A synthetic resin is injected from a portion corresponding to the circumference to integrally mold the bump stopper with the synthetic resin. Therefore, according to the bump stopper manufacturing method of the present invention, the bump stopper can be resin-molded without generating a weld line in the cylindrical portion.

  According to the bump stopper, the shock absorber, and the method for manufacturing the bump stopper of the present invention, it is possible to prevent cracks when the bump stopper is attached to the outer circumference of the end portion of the outer tube.

It is a side view of a shock absorber provided with a bump stopper in one embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of the bump stopper according to the embodiment of the present invention. FIG. 3 is an enlarged bottom view of the bump stopper according to the embodiment of the present invention. FIG. 7A is a diagram illustrating movement of the synthetic resin injected into the mold for forming the bump stopper according to the embodiment of the present invention. FIG. 6B is a diagram for explaining the subsequent movement of the synthetic resin injected into the mold for forming the bump stopper in the embodiment of the present invention. FIG. 7 is a partially enlarged cross-sectional view of a bump stopper in a modification of the embodiment of the present invention. It is a figure explaining the process of manufacturing the conventional bump stopper.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, the bump stopper 1 according to the embodiment is attached to the outer peripheral end portion of the outer tube 10 of the shock absorber D, and is attached to the tip end of the rod 11 of the shock absorber D. Is facing. When the shock absorber D contracts to a preset position, the bump stopper 1 contacts the lower end of the bump cushion rubber 13 in FIG. It exerts elastic force that suppresses contraction. In this way, the bump stopper 1 cooperates with the bump cushion rubber 13 to reduce the shock when the shock absorber D contracts the most.

  The shock absorber D includes a shock absorber body 9 having a cylindrical outer tube 10 and a rod 11 that is inserted into and retractable from the outer tube 10, and a bump stopper 1. A damping force is exerted when 11 expands and contracts in the axial direction. A bump stopper 1 is press-fitted onto the outer periphery of the upper end of the outer tube 10 in FIG.

  Although not shown in detail, the shock absorber D is connected to the cylinder housed in the outer tube 10 and the rod 11 and is movably inserted into the cylinder so that the inside of the cylinder becomes an expansion side chamber and a compression side chamber. A partitioning piston is provided, and a reservoir is provided between the cylinder and the outer tube 10. In addition, the expansion side chamber and the compression side chamber are filled with liquid, and the reservoir is filled with liquid and gas. Further, the shock absorber D is provided with a passage that communicates between the expansion side chamber and the compression side chamber and a passage that communicates between the compression side chamber and the reservoir, and a damping valve and a check valve for exerting damping force in these passages are appropriately provided. It is provided. The shock absorber D configured in this manner exerts a damping force that impedes the expansion by giving resistance to the flow of the liquid flowing from the expanding pressure side chamber to the contracting expansion side chamber at the time of expansion by the damping valve. On the contrary, when the shock absorber D contracts, the rod 11 enters the cylinder and the liquid is pushed out from the cylinder, and the damping valve applies resistance to the flow of the liquid from the pressure side chamber to the reservoir to prevent the contraction. Exert.

  Although the shock absorber D has been described as a double cylinder type shock absorber in the above description, the shock absorber D is not limited to the double cylinder type shock absorber and exhibits a damping force when the rod 11 moves in and out of the outer tube 10. If Therefore, the shock absorber D may be a single-cylinder (monotube) shock absorber in which the piston is directly inserted into the outer tube 10 to provide the expansion side chamber and the compression side chamber in the outer tube 10. Further, the shock absorber D may be a single rod type shock absorber or a double rod type shock absorber. The liquid used in the shock absorber D may be a liquid such as a magnetic viscous fluid, an electrorheological fluid, water, or an aqueous solution other than hydraulic oil. When using the magnetic viscous fluid or the electrorheological fluid, It is also possible to use a device that applies a magnetic field or an electric field to the passage instead of the damping valve.

  A cylindrical bump cushion rubber 13 is attached to the outer periphery of the tip of the rod 11. As shown in FIG. 1, the bump cushion rubber 13 is formed of a synthetic resin, rubber, or the like into a tubular shape having a bellows, and the lower end in FIG. 1 faces the bump stopper 1.

  The bump stopper 1 is made of synthetic resin in the present embodiment, and as shown in FIG. 1 to FIG. 3, it is arranged on an annular top portion 2 into which the rod 11 is inserted, and on the outer periphery of the top portion 2. And a connecting portion 4 that connects the top portion 2 and the cylindrical portion 3 and is provided with an annular groove 4a inside thereof.

  When the tubular portion 3 of the bump stopper 1 is press-fitted onto the outer periphery of the outer tube 10 of the shock absorber D and mounted on the outer tube 10, the top portion 2 faces the lower end of the bump cushion rubber 13. Then, the bump stopper 1 contacts the bump cushion rubber 13 when the shock absorber D is in the most contracted state, compresses the bump cushion rubber 13 and causes the bump cushion rubber 13 to exert an elastic force for suppressing the contraction of the shock absorber D.

  Hereinafter, the bump stopper 1 will be described in detail. The top portion 2 has an annular shape and is provided with a plurality of protrusions 2a provided at the lower end in FIG. In the present embodiment, six projections 2a are provided on the top portion 2, but the number of installations is arbitrary. When the bump stopper 1 is attached to the outer tube 10, the protrusion 2a comes into contact with the outer tube 10 and positions the position of the upper end in FIG. When the protrusion 2a is provided in this manner, when the upper end of the top portion 2 in FIG. 1 contacts the bump cushion rubber 13, the bump cushion rubber 13 seals the outer periphery of the rod 11 of the shock absorber D located on the inner periphery of the top portion 2. It is possible to prevent interference with the sealing member 14 that operates. Further, when the protrusion 2a is provided, the thickness of the top portion 2 can be partially increased, which is advantageous in strength.

  A plurality of ribs 3a along the axial direction are provided inside the tubular portion 3 at equal intervals in the circumferential direction. Six ribs 3a are provided on the tubular portion 3, and are provided at positions that overlap the protrusions 2a in the radial direction. The number of ribs 3a installed is arbitrary and may be installed between the protrusions 2a, 2a when viewed in the circumferential direction. In this way, if the rib 3a is provided inside the tubular portion 3, the rib 3a comes into contact with the outer circumference of the outer tube 10 when it is press-fitted onto the outer circumference of the outer tube 10, so that the pressing force of the bump stopper 1 against the outer tube 10 is increased. Even if the value is increased, press-fitting work becomes easy.

  Then, as shown in FIG. 2, the top portion 2 and the tubular portion 3 are connected by the connecting portion 4 that connects the outer periphery of the top portion 2 and the upper end of the tubular portion 3. The connecting portion 4 is a portion that just hits the shoulder of the bump stopper 1, and is located between the top portion 2 and the tubular portion 3. The connecting portion 4 is provided with an annular groove 4a on the inner side facing the inner side of the bump stopper 1 so as to surround the outer periphery of the top portion 2. The wall thickness T1 from the bottom of the annular groove 4a to the outside of the connecting portion 4 is smaller than the minimum wall thickness T2 at the top. Further, in the present embodiment, the minimum wall thickness of the tubular portion 3 is a portion other than the rib 3a of the tubular portion 3 shown by the broken line in FIG. 2, but from the bottom of the annular groove 4a to the outside of the connecting portion 4. Is less than the minimum thickness T3 of the tubular portion 3. In the present embodiment, the annular groove 4a has an annular shape as shown in FIG. 3, but the annular groove 4a may have a shape other than the annular shape as long as it surrounds the outer periphery of the top portion 2.

  The bump stopper 1 thus configured is molded by injecting a synthetic resin into the mold M, as shown in FIG. The mold M is internally provided with a gap that imitates the outer shape of the bump stopper 1, and is divided into a plurality of parts although not shown. Further, in order to facilitate understanding when molding the bump stopper 1, in FIG. 4, the cross section of the portion forming the rib 3a of the cylindrical portion 3 of the mold M is in the left half and the rib 3a of the cylindrical portion 3 of the mold M is shown. The cross section of the portion forming the other is shown in the right half.

  Then, when a synthetic resin is injected into the mold M, the top portion 2, the tubular portion 3, and the connecting portion 4 are integrally molded, and the bump stopper 1 can be resin-molded.

  As shown in FIG. 4, the synthetic resin R is injected into the mold M from a plurality of positions corresponding to the inner circumference of the top portion 2 of the mold M. The number of locations where the synthetic resin is injected into the mold M is arbitrary, but it is set to three or more locations in order to suppress the generation of weld lines.

  Then, when the synthetic resin R is injected into the mold M, as shown in FIG. 4A, first, the synthetic resin R fills the part corresponding to the top 2 of the bump stopper 1 in the mold M. Furthermore, when the synthetic resin R is injected into the mold M, the synthetic resin R becomes difficult to pass through the narrow gap S1 corresponding to the annular groove 4a of the connecting portion 4, as shown in FIG. 4B. At one end, it can be blocked by this narrow gap, but when it passes through this narrow gap, it enters the wide gap corresponding to the cylindrical portion 3 and quickly fills this gap. In this way, the synthetic resin R is squeezed by the narrow gap S1 corresponding to the annular groove 4a of the mold M and is filled into the gap corresponding to the tubular portion 3. Therefore, the synthetic resin R quickly fills the wide gap S2 corresponding to the rib 3a of the cylindrical portion 3 in the mold M and the gap S3 narrower than the gap S2 corresponding to the portion other than the rib 3a. That is, since the annular groove 4a is provided in the connecting portion 4 between the top portion 2 of the bump stopper 1 and the cylindrical portion 3 to provide a portion whose thickness is smaller than the minimum thickness of the top portion 2, the connection in the mold M is made. A narrow gap S1 that functions as a diaphragm for squeezing the synthetic resin R injected into the mold M is provided at a portion corresponding to the portion 4. By doing so, as described above, the synthetic resin R is promptly provided not only in the gap S2 corresponding to the rib 3a among the gaps in the portion corresponding to the cylindrical portion 3 in the mold M but also in the gap S3 corresponding to the portions other than the rib 3a. It will be filled. Therefore, it is possible to prevent the synthetic resin R from entering not only the gap S1 but also the wide gap S2 corresponding to the rib 3a into the narrow gap S3 corresponding to the portion other than the rib 3a of the tubular portion 3 in the mold M, and the thin wall of the tubular portion 3 It is possible to prevent a weld line from being generated in the area.

  As described above, the bump stopper 1 has an annular top portion 2, a tubular portion 3 arranged on the outer periphery of the top portion 2, an annular groove that connects the top portion 2 and the tubular portion 3 and surrounds the outer periphery of the top portion 2 inside. The connecting portion 4 having 4a is integrally molded of synthetic resin, and the thickness T1 from the bottom of the annular groove 4a in the connecting portion 4 to the outside of the connecting portion 4 is smaller than the minimum thickness T2 of the top portion 2. Is configured to be.

  The bump stopper 1 configured as described above can prevent a weld line from being generated in a thin portion other than the rib 3a of the tubular portion 3 when the resin is molded by the mold M. Further, since the bump stopper 1 configured as described above can prevent the weld line from being generated in the tubular portion 3, even if the tightness of the tubular portion 3 to the outer tube 10 is increased, the tubular portion 3 is not cracked. There is no worry about it occurring. Furthermore, since the connecting portion 4 is provided with the annular groove 4a, the connecting portion 4 can be flexibly deformed when the tubular portion 3 is press-fitted onto the outer periphery of the outer tube 10, so that the tubular portion 3 is pressed against the outer tube 10. Even if the force is increased, there is no concern that the connection portion 4 will crack. Therefore, according to the bump stopper 1 of the present invention, it is possible to prevent cracks when the outer tube 10 is attached to the outer circumference of the end portion. Further, according to the shock absorber D including the bump stopper 1, it is possible to prevent cracks when the bump stopper 1 is attached to the outer circumference of the end portion of the outer tube 10.

  When the bump stopper 1 is press-fitted into the outer tube 10, the rib 3a may rub against the outer circumference of the outer tube 10 to generate shavings. However, in the bump stopper 1 of the present invention, since the annular groove 4a is provided inside the connecting portion 4, the shavings can be accommodated in the annular groove 4a, and the shavings can be accommodated between the top 2 and the outer tube 10. It can prevent biting.

  The annular groove 4a is formed along the up-down direction in FIGS. 2 and 3, but is not limited to this. That is, if the shortest distance between the bottom of the annular groove 4a and the outside of the connecting portion 4 is smaller than the minimum wall thickness of the top portion 2, a drawing effect is obtained when the bump stopper 1 is molded by the mold M, and the tubular portion 3 is formed. The synthetic resin R is promptly filled in the entire area. Therefore, the annular groove 4a may be formed in the horizontal direction or the inclined direction with respect to the bump stopper 1, as shown by the solid line or the broken line in FIG.

  In the bump stopper 1 of the present embodiment, the wall thickness T1 from the bottom of the annular groove 4a to the outside of the connecting portion 4 is less than or equal to the minimum wall thickness T3 of the tubular portion 3. By doing so, the narrow gap S3 corresponding to the portions other than the ribs 3a of the cylindrical portion 3 in the mold M becomes equal to or wider than the gap S1 corresponding to the portion of the mold M where the annular groove 4a is provided, so that the synthetic resin R The gap S3 is filled more quickly. According to the bump stopper 1 configured as described above, since the generation of weld lines in the tubular portion 3 can be effectively suppressed, the strength improving effect of the tubular portion 3 is enhanced.

  Further, in the bump stopper 1 of the present embodiment, the top portion 2 has a plurality of protrusions 2a arranged inward in the circumferential direction, and the tubular portion 3 has a plurality of ribs 3a arranged inward in the circumferential direction. There is. Since the bump stopper 1 configured as described above is provided with the protrusions 2a and the ribs 3a, the strength of the bump stopper 1 is improved and the portions other than the ribs 3a of the tubular portion 3 are easily deformed even if the amount of tightening is increased. Press-in work becomes easy.

  Further, since the bump stopper 1 of the present embodiment is provided at the position where the protrusion 2a and the rib 3a overlap in the radial direction, it is possible to prevent water, dust, and the like that have entered the annular groove 4a from escaping from the annular groove 4a. The protrusion 2a and the rib 3a do not interfere. When the protrusions 2a and the ribs 3a are alternately arranged in the circumferential direction, the annular groove has a shape that avoids the protrusions 2a and the ribs 3a, and does not have a clean annular shape. Although difficult, in the bump stopper 1 of the present embodiment, water, dust and the like that have entered the annular groove 4a are quickly discharged.

  Further, according to the method of manufacturing the bump stopper 1 of the present invention, the ring-shaped top portion 2, the cylindrical portion 3 arranged on the outer periphery of the top portion 2, the top portion 2 and the cylindrical portion 3 are connected, and the outer periphery of the top portion 2 is arranged inside. And a connecting portion 4 having an annular groove 4a provided along the connecting portion 4, and the thickness of the connecting portion 4 from the bottom of the annular groove 4a to the outside of the connecting portion 4 is smaller than the minimum thickness of the top portion 2. The synthetic resin R is injected into the mold M for molding the bump stopper 1 from a position corresponding to the inner circumference of the top portion 2 of the mold M to integrally mold the bump stopper 1 with the synthetic resin R. In the method for manufacturing the bump stopper 1 according to the present invention, when the synthetic resin R is injected from a portion corresponding to the inner circumference of the top portion 2 of the mold M, the synthetic resin R is annularly formed in the connecting portion 4 of the mold M while reaching the tubular portion 3. Since it passes through the narrow gap S1 corresponding to the groove 4a, the gap S1 functions as a diaphragm and the synthetic resin R can be quickly filled into the entire cylindrical portion 3. Therefore, according to the method for manufacturing the bump stopper 1 of the present invention, the bump stopper 1 can be resin-molded without generating a weld line in the tubular portion 3.

  The preferred embodiments of the present invention have been described above in detail, but modifications, variations, and changes can be made without departing from the scope of the claims.

1 ... Bump stopper, 2 ... Top part, 2a ... Protrusion, 3 ... Cylindrical part, 3a ... Rib, 4 ... Connection part, 4a ... Annular groove, 9 ... Shock absorber body, 10 ... outer tube, 11 ... rod, D ... shock absorber, M ... type, R ... synthetic resin

Claims (6)

An annular top,
A tubular portion arranged on the outer periphery of the top portion,
A bump stopper integrally formed of synthetic resin, comprising a connecting portion that connects the top portion and the cylindrical portion and has an annular groove that surrounds the outer periphery of the top portion inside,
The bump stopper, wherein the thickness of the connecting portion from the bottom of the annular groove to the outside of the connecting portion is smaller than the minimum thickness of the top portion. The bump stopper according to claim 1, wherein a thickness from a bottom of the annular groove in the connection portion to an outside of the connection portion is equal to or less than a minimum thickness of the tubular portion. The top portion has a plurality of protrusions arranged inward along the circumferential direction,
The bump stopper according to claim 1 or 2, wherein the tubular portion has a plurality of ribs arranged inside along the circumferential direction. The bump stopper according to claim 3, wherein the protrusion and the rib are provided at a position overlapping in the radial direction. An outer tube and a shock absorber body that has a rod that moves in and out of the outer tube, and that exerts a damping force when the rod moves in and out of the outer tube,
A bumper comprising the bump stopper according to any one of claims 1 to 4. A method of manufacturing a bump stopper, comprising:
An annular top portion, a tubular portion arranged on the outer circumference of the top portion, and a connecting portion that connects the top portion and the tubular portion and has an annular groove provided inside along the outer circumference of the top portion. A wall thickness from the bottom of the annular groove in the connection portion to the outside of the connection portion is smaller than the minimum wall thickness in the top portion, inside the mold for forming the bump stopper, the inner periphery of the top portion of the mold A method of manufacturing a bump stopper, characterized in that a synthetic resin is injected from a portion corresponding to, and the bump stopper is integrally molded with the resin.

Images