JP2020034065A - Bump stopper, shock absorber, and bump stopper manufacturing method - Google Patents

Abstract

To provide a bump stopper which can prevent cracking when attached to an end part outer periphery of an outer tube, and to provide a shock absorber and a bump stopper manufacturing method.SOLUTION: A bump stopper 1 is integrally molded by a synthetic resin including: an annular apex 2; a cylinder part 3 disposed at an outer periphery of the apex 2; and a connection part 4 which connects the apex 2 with the cylinder part 3 and has an annular groove 4a which encloses an outer periphery of the apex 2 therein. The bump stopper 1 is configured so that a thickness T1 from a bottom of the annular groove 4a to the outer side of the connection part 4 in the connection part 4 becomes thinner than a minimum thickness T2 in the apex 2.SELECTED DRAWING: Figure 2

Description

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

  Conventionally, a shock absorber has an outer tube, a rod inserted into and out of the outer tube, and a bump stopper rubber provided on a rod side and a bump stopper provided on an end of the outer tube.

  In such a shock absorber, at the time of the most contraction in which the rod enters the outer tube most, the bump stopper rubber abuts against the bump stopper and is compressed, so that the bump stopper rubber exerts a resilient force. Shock is reduced.

  The bump stopper includes a cylindrical portion having a perfectly circular cross section fitted to the outer periphery of the end portion of the outer tube, and an annular stopper portion provided at the top of the cylindrical portion and facing the bump cushion rubber and allowing the rod to pass therethrough. And fitted to the outer periphery of the end of the outer tube.

  More specifically, the bump stopper has a plurality of ribs arranged in the circumferential direction on the inner periphery of the cylindrical portion, and presses the ribs on the outer periphery of the outer tube to tighten the outer tube and fix the outer tube to the outer tube. (For example, see Patent Document 1). In other words, the conventional bump stopper is fixed to the outer tube by press-fitting, thereby preventing the bump stopper from falling off from the outer tube.

  Therefore, if the diameter of the cylinder is reduced and the tension is increased, the bump stopper is securely fixed to the outer tube.However, when the bump stopper is pressed into the outer periphery of the end of the outer tube, the top, the cylinder and There is a possibility that a large stress acts on the joint of the bump and the bump stopper is cracked. For this reason, in the conventional bump stopper, an annular groove is provided on the outer peripheral portion of the inner surface of the top to reduce the concentration of stress on the joint.

JP 2007-57088 A

  Such a conventional bump stopper is integrally molded of a synthetic resin. As shown in FIG. 6, a synthetic resin is injected into a mold 100 for molding the bump stopper from a portion corresponding to the inner periphery of the top of the mold 100. It may be molded.

  Since the bump stopper is provided with a plurality of ribs in the cylindrical portion, the gap between the portions corresponding to the cylindrical 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 part corresponding to other than becomes narrow.

  When the synthetic resin is injected into the mold 100, the synthetic resin quickly enters a wide portion of the mold 100, but takes time to enter a narrow portion. Therefore, in the narrow portion in the mold 100, the synthetic resin cools down, and a flow of the synthetic resin entering from the wide portion can occur, so that the thin portion of the cylindrical portion of the formed bump stopper is thin. A weld line is generated.

  Since the location where the weld line occurs becomes weaker in strength, if the weld line occurs in the thin part of the cylinder part of the bump stopper, the bump stopper will be broken when the bump stopper is pressed into the outer tube. there is a possibility.

  Therefore, the present invention provides a bump stopper and a shock absorber including the bump stopper, which can prevent cracking at the time of attachment to the outer periphery of the end of the outer tube. An object of the present invention is to provide a method for manufacturing a bump stopper that can prevent cracking.

  In order to solve the above-described object, 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, and an annular shape connecting the top portion and the tubular portion and inwardly surrounding the outer periphery of the top portion. A connection portion having a groove, and is integrally molded with synthetic resin, and is configured such that a thickness from a bottom of the annular groove to an outside of the connection portion at the connection portion is smaller than a minimum thickness at a top portion. .

  The bump stopper configured as described above can prevent a weld line from being generated in a thin portion other than the rib of the cylindrical portion when the resin is molded in a mold. Further, since the bump stopper having such a configuration can prevent the weld line from being generated in the cylindrical portion, there is no fear that the cylindrical portion 3 is cracked even if the tightening force of the cylindrical portion against the outer tube is increased. Absent. Furthermore, since the connecting portion has an annular groove, the connecting portion can be flexibly deformed when the cylindrical portion is pressed into the outer periphery of the outer tube, so that the connecting portion can be connected even if the tightening force of the cylindrical portion on the outer tube is increased. There is no worry about cracks occurring in the part.

  The thickness of the bump stopper from the bottom of the annular groove to the outside of the connection portion may be equal to or less than the minimum thickness of the cylindrical portion. According to the bump stopper configured as described above, the occurrence of weld lines in the cylindrical portion can be effectively suppressed, and the effect of improving the strength of the cylindrical portion is also increased.

  Further, the bump stopper may have a plurality of protrusions whose tops are arranged inwardly along the circumferential direction, and a plurality of ribs whose cylindrical portion is arranged inwardly along the circumferential direction. The bump stopper thus configured has the protrusion and the rib, so that the strength of the bump stopper is improved, and even if the amount of tension is increased, the portion other than the rib of the cylindrical portion is easily deformed, thereby facilitating the press-fitting operation. .

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

  Further, the shock absorber of the present invention has an outer tube, a rod that moves in and out of the outer tube, a shock absorber body that exerts a damping force when the rod moves in and out of the outer tube, and the bump stopper It has. According to the shock absorber configured as described above, even if the bump stopper is pressed into the outer periphery of the outer tube, there is no fear that a crack is generated.

  Further, the method of manufacturing a bump stopper according to the present invention includes an annular top portion, a tubular portion disposed on the outer periphery of the top portion, and an annular groove connecting the top portion and the tubular portion and provided inside along the outer periphery of the top portion. And a connecting part having a thickness from the bottom of the annular groove to the outside of the connecting part at the connecting part is smaller than the minimum 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.

  ADVANTAGE OF THE INVENTION According to the manufacturing method of a bump stopper, a shock absorber, and a bump stopper of this invention, the crack at the time of mounting | wearing the outer periphery of the end part of an outer tube of a bump stopper can be prevented.

It is a side view of the shock absorber provided with the bump stopper in one embodiment of the present invention. It is an expanded sectional view of a bump stopper in one embodiment of the present invention. It is an enlarged bottom view of a bump stopper in one embodiment of the present invention. (A) is a figure explaining the movement of the synthetic resin injected into the die | mould which shape | molds a bump stopper in one Embodiment of this invention. (B) is a figure explaining the subsequent movement of the synthetic resin injected into the die | mould which shape | molds a bump stopper in one Embodiment of this invention. It is a partially expanded sectional view of a bump stopper in a modification of one embodiment of the present invention. It is a figure explaining a process of manufacturing a conventional bump stopper.

  Hereinafter, the present invention will be described based on the embodiment shown in the drawings. As shown in FIG. 1, the bump stopper 1 according to one embodiment is mounted on the outer peripheral end of the outer tube 10 of the shock absorber D, and is mounted on the tip of the rod 11 of the shock absorber D. Facing. When the bumper D contracts to a preset position, the bump stopper 1 comes into contact with the lower end of the bump cushion rubber 13 in FIG. 1 to compress the bump cushion rubber 13 and to attach the bumper rubber 13 to the bump cushion rubber 13. Exhibits elasticity that suppresses contraction. As described above, the bump stopper 1 cooperates with the bump cushion rubber 13 to reduce the shock when the shock absorber D contracts most.

  The shock absorber D includes a shock absorber main body 9 having a cylindrical outer tube 10 and a rod 11 inserted into and out of the outer tube 10 and the bump stopper 1. 11 exerts a damping force when it expands and contracts in the axial direction. A bump stopper 1 is press-fitted around the upper end of the outer tube 10 in FIG.

  Although not shown in detail, the shock absorber D is connected to the cylinder accommodated in the outer tube 10 and the rod 11, and is movably inserted into the cylinder so as to extend through the cylinder into a side chamber and a pressure chamber. A partitioning piston is provided, and a reservoir is provided between the cylinder and the outer tube 10. 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 communicating the extension side chamber and the compression side chamber and a passage communicating the compression side chamber with the reservoir, and a damping valve and a check valve for exerting a damping force in these passages are appropriately provided. Provided. When the shock absorber D is configured to extend, the damper D exerts a damping force that impedes expansion by imparting resistance to the flow of liquid from the expanding pressure side chamber to the contracting expansion side chamber by the damping valve. Conversely, when the shock absorber D contracts, the rod 11 penetrates into the cylinder, the liquid is pushed out from the cylinder, and the damping force that impedes the contraction by giving resistance to the flow of the liquid from the pressure side chamber to the reservoir by the damping valve. Demonstrate.

  In the above description, the shock absorber D is described as a double-cylinder type shock absorber. However, the shock absorber D is not limited to the double-cylinder type and exhibits a damping force when the rod 11 enters and exits the outer tube 10. Should be fine. Therefore, the shock absorber D may be a single-tube (mono-tube) shock absorber in which a piston is directly inserted into the outer tube 10 and the extension side chamber and the pressure side chamber are provided inside 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 in addition to the hydraulic oil. Instead of a damping valve, a device for applying a magnetic field or an electric field to a passage can be used.

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

  The bump stopper 1 is made of a synthetic resin in the present embodiment, and is disposed on an annular top 2 through which a rod 11 is inserted and an outer periphery of the top 2 as shown in FIGS. And a connecting portion 4 connecting the top portion 2 and the cylindrical portion 3 and having an annular groove 4a provided inside.

  When the bump stopper 1 is mounted on the outer tube 10 by press-fitting the cylindrical portion 3 to the outer periphery of the end portion of the outer tube 10 of the shock absorber D, the top 2 faces the lower end of the bump cushion rubber 13. The bump stopper 1 comes into contact with the bump cushion rubber 13 when the shock absorber D is most contracted, and compresses the bump cushion rubber 13 to cause the bump cushion rubber 13 to exhibit an elastic force for suppressing the contraction of the shock absorber D.

  Hereinafter, the bump stopper 1 will be described in detail. The top 2 is annular and has a plurality of protrusions 2a provided at equal intervals in the circumferential direction at the lower end in FIG. In the present embodiment, six protrusions 2a are provided on the top portion 2, but the number of protrusions 2a is arbitrary. When the bump stopper 1 is mounted on the outer tube 10, the protrusion 2 a 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 way, when the upper end of the top 2 in FIG. 1 abuts against 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 2. Interference with the sealing member 14 can be prevented. Further, when the projections 2a are provided, the thickness of the top 2 can be partially increased, which is advantageous in strength.

  A plurality of ribs 3a along the axial direction are provided at equal intervals in the circumferential direction inside the cylindrical portion 3. Six ribs 3a are provided on the cylindrical portion 3, and are provided at positions overlapping the protrusions 2a in the radial direction. The number of the ribs 3a is arbitrary, and the ribs 3a may be provided between the protrusions 2a when viewed in the circumferential direction. When the rib 3a is provided inside the cylindrical portion 3 as described above, the rib 3a abuts on the outer periphery of the outer tube 10 when pressed into the outer periphery of the outer tube 10, so that the tightening force of the bump stopper 1 against the outer tube 10 is provided. Pressing work becomes easy even if is increased.

  Then, as shown in FIG. 2, the top 2 and the cylindrical portion 3 are connected by a connecting portion 4 that connects the outer periphery of the top 2 and the upper end of the cylindrical portion 3. The connecting portion 4 is a portion just hitting the shoulder of the bump stopper 1 and is located between the top 2 and the cylindrical portion 3. The connecting portion 4 has an annular groove 4 a on the inside facing the inside of the bump stopper 1 so as to surround the outer periphery of the top 2. The thickness T1 from the bottom of the annular groove 4a to the outside of the connection portion 4 is smaller than the minimum thickness T2 at the top. Further, in the present embodiment, the minimum thickness of the cylindrical portion 3 is a portion other than the rib 3a of the cylindrical portion 3 shown by a 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 or equal to the minimum thickness T3 of the cylindrical portion 3. In the present embodiment, the annular groove 4a is formed in an annular shape as shown in FIG. 3, but may be formed in a shape other than an annular shape as long as it surrounds the outer periphery of the top portion 2.

  The bump stopper 1 thus configured is formed by injecting a synthetic resin into a mold M as shown in FIG. The mold M has a gap imitating the outer shape of the bump stopper 1 inside, and is divided into a plurality of parts (not shown). In order to facilitate understanding when forming the bump stopper 1, in FIG. 4, the cross section of the portion where the rib 3 a of the cylindrical portion 3 of the mold M is formed is a left half, and the rib 3 a of the cylindrical portion 3 of the mold M is shown in FIG. The cross section of the part forming the other is shown in the right half.

  When the synthetic resin is injected into the mold M, the top portion 2, the cylindrical portion 3, and the connecting portion 4 are integrally formed, 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 locations corresponding to the inner periphery of the top 2 of the mold M. The number of locations where the synthetic resin is injected into the mold M is arbitrary, but is set to three or more in order to suppress the occurrence of weld lines.

  Then, when the synthetic resin R is injected into the mold M, the synthetic resin R first fills a portion corresponding to the top 2 of the bump stopper 1 in the mold M, as shown in FIG. Further, when the synthetic resin R is injected into the mold M, as shown in FIG. 4B, the synthetic resin R is less likely to pass through the narrow gap S1 corresponding to the annular groove 4a of the connection portion 4. One end is blocked by this narrow gap, but when passing through this narrow gap, it enters the wide gap corresponding to the cylindrical portion 3 and fills this gap quickly. As described above, the synthetic resin R is filled in the gap corresponding to the cylindrical portion 3 while being narrowed down by the narrow gap S1 corresponding to the annular groove 4a of the mold M. Therefore, the synthetic resin R is quickly filled in 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 and the cylindrical portion 3 of the bump stopper 1 to provide a portion whose thickness is smaller than the minimum thickness of the top portion 2, the connection in the mold M is performed. A narrow gap S1 functioning as a diaphragm for restricting 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 quickly enters not only the gap S2 corresponding to the rib 3a but also the gap S3 corresponding to portions other than the rib 3a among the gaps at the portion corresponding to the cylindrical portion 3 in the mold M. It is filled. Accordingly, it is possible to prevent the synthetic resin R from flowing around 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 cylindrical portion 3 in the mold M. A weld line can be prevented from being generated at the part.

  As described above, the bump stopper 1 includes the annular top 2, the cylindrical portion 3 disposed on the outer periphery of the top 2, and the annular groove connecting the top 2 and the cylindrical portion 3 and surrounding the outer periphery of the top 2 inside. And a connecting portion 4 having a connecting portion 4a. The connecting portion 4 is integrally molded with a synthetic resin, and the thickness T1 from the bottom of the annular groove 4a to the outside of the connecting portion 4 in the connecting portion 4 is smaller than the minimum thickness T2 in the top portion 2. It is configured to be.

  The bump stopper 1 configured as described above can prevent a weld line from being generated at a thin portion other than the rib 3a of the cylindrical portion 3 when the resin is molded by the mold M. In addition, since the bump stopper 1 configured as described above can prevent a weld line from being generated in the cylindrical portion 3, even if the tightening force of the cylindrical portion 3 against the outer tube 10 is increased, the cylindrical portion 3 is not cracked. There is no need to worry. Further, since the connecting portion 4 has the annular groove 4a, the connecting portion 4 can be flexibly deformed when the cylindrical portion 3 is pressed into the outer periphery of the outer tube 10, so that the tightness of the cylindrical portion 3 against the outer tube 10 is achieved. Even if the force is increased, there is no fear that the connection portion 4 is cracked. 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 periphery of the end. Further, according to the shock absorber D including the bump stopper 1, it is possible to prevent the bump stopper 1 from being cracked when being mounted on the outer periphery of the end of the outer tube 10.

  When the bump stopper 1 is pressed into the outer tube 10, the ribs 3a may be rubbed against the outer periphery of the outer tube 10 to generate shavings. However, in the bump stopper 1 of the present invention, since the annular groove 4 a is provided inside the connection portion 4, the shavings can be accommodated in the annular groove 4 a, and the shavings can be accommodated between the top 2 of the shavings and the outer tube 10. Biting can be prevented.

  Further, the annular groove 4a is formed along the vertical direction in the place shown in FIGS. 2 and 3, but is not limited to this. In other words, if the shortest distance between the bottom of the annular groove 4a and the outside of the connection portion 4 is smaller than the minimum thickness of the top portion 2, a drawing effect can be obtained when the bump stopper 1 is formed by the mold M, and the cylindrical portion 3 Is quickly filled with the synthetic resin R. Therefore, the annular groove 4a may be formed in a horizontal direction or an inclined direction with respect to the bump stopper 1 as shown by a solid line or a broken line in FIG.

  In the bump stopper 1 of the present embodiment, the thickness T1 from the bottom of the annular groove 4a to the outside of the connection portion 4 is equal to or less than the minimum thickness T3 of the cylindrical portion 3. By doing so, the narrow gap S3 corresponding to the portion other than the rib 3a of the cylindrical portion 3 in the mold M is equal to or wider than the gap S1 corresponding to the portion of the mold M where the annular groove 4a is provided. The gap S3 is more quickly filled. According to the bump stopper 1 configured as described above, the occurrence of a weld line in the cylindrical portion 3 can be effectively suppressed, and the effect of improving the strength of the cylindrical portion 3 is also enhanced.

  Further, the bump stopper 1 of the present embodiment includes a plurality of ribs 3a in which the top 2 has a plurality of protrusions 2a arranged inwardly along the circumferential direction, and the cylindrical portion 3 has a plurality of ribs 3a arranged inwardly along the circumferential direction. I have. Since the bump stopper 1 having such a configuration is provided with the projections 2a and the ribs 3a, the strength of the bump stopper 1 is improved, and the portions other than the ribs 3a of the cylindrical portion 3 are easily deformed even if the amount of tension is increased. Pressing work becomes easy.

  Further, since the bump stopper 1 of the present embodiment is provided at a position where the protrusion 2a and the rib 3a overlap in the radial direction, it is necessary to prevent water, dust, and the like entering the annular groove 4a from escaping from the annular groove 4a. The projection 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 is shaped so as to avoid the protrusions 2a and the ribs 3a, does not form a clean circular shape, and water and dust entering the annular groove 4a are discharged. Although it is 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.

  Furthermore, the method of manufacturing the bump stopper 1 of the present invention includes the step of connecting the annular top 2, the cylindrical portion 3 disposed on the outer periphery of the top 2, the top 2 and the cylindrical portion 3, and inwardly forming the outer periphery of the top 2. And a connecting portion 4 having an annular groove 4a provided along the connecting portion 4. 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 periphery of the top 2 of the mold M, and the bump stopper 1 is integrally molded with the synthetic resin R. In the method of manufacturing the bump stopper 1 of the present invention, when the synthetic resin R is injected from a portion corresponding to the inner periphery of the top 2 of the mold M, the annular portion of the connecting portion 4 of the mold M is moved while the synthetic resin R reaches the cylindrical portion 3. Since the gas passes through the narrow gap S1 corresponding to the groove 4a, the gap S1 functions as a throttle and the synthetic resin R can be quickly filled in 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 cylindrical portion 3.

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

DESCRIPTION OF SYMBOLS 1 ... Bump stopper, 2 ... Top part, 2a ... Projection, 3 ... Cylindrical part, 3a ... Rib, 4 ... Connection part, 4a ... Annular groove, 9 ... Shock absorber main 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 which is integrally molded with a synthetic resin, comprising a connection portion connecting the top portion and the cylindrical portion and having an annular groove surrounding the outer periphery of the top portion inside,
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. 2. The bump stopper according to claim 1, wherein a thickness of the connection portion from a bottom of the annular groove to an outside of the connection portion is equal to or less than a minimum thickness of the cylindrical portion. 3. The top has a plurality of protrusions arranged in a circumferential direction inside,
3. The bump stopper according to claim 1, wherein the cylindrical portion has a plurality of ribs arranged inward in the circumferential direction. 4. 4. The bump stopper according to claim 3, wherein the protrusion and the rib are provided at positions overlapping in a radial direction. 5. An outer tube, and a shock absorber body having a rod that moves in and out of the outer tube, and that exhibits a damping force when the rod moves in and out of the outer tube;
A shock absorber comprising the bump stopper according to any one of claims 1 to 4. A method for manufacturing a bump stopper,
An annular top portion, a tubular portion arranged on the outer periphery of the top portion, and a connecting portion connecting the top portion and the tubular portion and having an annular groove provided inside along the outer periphery of the top portion. An inner circumference of the top of the mold in a mold for molding the bump stopper, wherein a thickness from a bottom of the annular groove to an outside of the connection at the connection is smaller than a minimum thickness at the top; A method of manufacturing a bump stopper, comprising: injecting a synthetic resin from a portion corresponding to the above, and integrally molding the bump stopper with the resin.

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