JP2005188540A - Hydraulic damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure for a dust cover to be inexpensively mounted on a hydraulic damper in which the stroke length of a piston rod is set greater in an elongation stroke than in a contraction stroke, without any troubles. <P>SOLUTION: The hydraulic damper comprises a bump rubber 12 fixed to the front end of the piston rod, a bump stopper 7 provided at the opening end of a cylinder 2 for abutting on the bump rubber 12, and a bellows dust cover 15 arranged on the outer periphery of the piston rod 8 to cover the bump cover 12, the bump stopper 7 and the piston rod 8. The front end of the dust cover 15 is fixed to the front end of the piston rod 8, while a restricting member 9 is provided on the bump stopper 7 on which a base end 15a of the dust cover 15 abuts. Thus, in the contraction stroke of the piston rod 8, the base end 15a of the dust cover 15 is prevented from moving to the base end of the cylinder 2 by the restricting member 9. The restricting member 9 has an alignment portion 9a for alignment action of the dust cover 15 on the cylinder 2 with the abutment of the base end 15a of the dust cover 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber used for a vehicle such as an automobile, and more particularly to a dust cover mounting structure that covers a piston rod.

  Among hydraulic shock absorbers used in suspension devices for vehicles such as automobiles, a dust cover for covering and protecting the piston rod on the outer periphery of the piston rod is disclosed as dust in the hydraulic shock absorber shown in Patent Document 1. A cover fixing structure can be exemplified.

  That is, the front end portion of the bellows-shaped dust cover is fixed to the piston rod front end side, and a skirt portion with reduced rigidity is extended to the base end portion of the cover, and a locking portion provided on the skirt portion is provided. The base end portion of the dust cover is fixed to the outer tube side by engaging with the flange portion of the bump stopper cap attached to the opening end portion of the outer tube.

According to this, since the base end portion of the dust cover does not move below the bump stopper cap even in the contraction process in which the piston rod enters the outer tube, the spring seat is located below the bump stopper cap. There is an advantage that it is possible to prevent the rusting caused by peeling off of the coating of the spring sheet caused by the base end part contacting the spring sheet.
JP 2003-65381 A (FIGS. 1 to 5)

  In the above structure, an operation of locking the base end portion of the dust cover to the flange portion of the bump stopper cap is required, and there is a problem that the assembling cost increases accordingly.

  In addition, the stroke length of the extension stroke in which the piston rod retracts from the outer tube is set to be extremely longer than the stroke length of the contraction stroke in which the piston rod enters the outer tube from the state where it is mounted on the vehicle body. When the above dust cover fixing structure is used for the hydraulic shock absorber, the following problems occur.

  That is, when the outer diameter of the bellows part of the bellows part, the inner diameter of the valley part, the number of peaks, etc. are set so that the bellows part of the dust cover is most folded when the piston rod is in the most contracted state, There is a problem in that the bellows part is stretched in the middle of the process, and the length in the axial direction is insufficient.

  Therefore, it is conceivable to set the length of the bellows portion itself to a length corresponding to the stroke length in the extension stroke, but in this case, the bellows portion is further compressed than in the most folded state during the contraction stroke. Therefore, it is conceivable that a problem occurs that the bellows part is damaged by being crushed in the outer peripheral direction and contacting the suspension spring.

  An object of the present invention is to provide a dust cover mounting structure that can be mounted at low cost without problems even with a hydraulic shock absorber in which the stroke length of the piston rod is set longer than the contraction stroke. is there.

  In order to achieve the above object, the present invention fixes a bump rubber to the tip end side of a piston rod, and provides a bump stopper that contacts the bump rubber at the cylinder opening end. These bump rubber, bump stopper, and piston In the hydraulic shock absorber having a bellows-like dust cover arranged on the outer periphery of the piston rod so as to cover the rod, the tip of the dust cover is fixed to the tip of the piston rod, while the base end of the dust cover is fixed to the bump stopper. A restricting member with which the portion abuts is provided to prevent the base end portion of the dust cover from moving toward the cylinder base end side from the restricting member during the contraction stroke of the piston rod. An aligning portion for aligning the dust cover with the cylinder by contact is provided.

  According to the present invention, in the contraction stroke in which the piston rod enters the cylinder, the dust cover having the tip attached to the piston rod moves downward with the penetration of the piston rod. Since the portion abuts on the regulating member provided on the bump stopper and the movement toward the cylinder base end side is further regulated, the base end portion abuts on another member positioned on the cylinder base side from the regulating member. Therefore, it is possible to reliably prevent the rust caused by peeling off of the coating of the other member caused by the base end of the dust cover coming into contact with the other member.

  Even if the shaft center of the dust cover and the shaft center of the cylinder are in contact with each other during the contraction stroke, the regulating member has a centering portion, so the base end of the dust cover is the centering portion. This will automatically align the misalignment. Therefore, it is possible to prevent the misalignment between the dust cover and the cylinder from impairing the smooth operation of the piston rod.

Also, during the extension stroke in which the piston rod retracts from the cylinder, the dust cover with the tip attached to the piston rod moves upward as the piston rod retracts, but the base end of the dust cover is fixed to the cylinder. Even if the hydraulic shock absorber is set to have a longer stroke length than that of the contraction stroke, the bellows part will be stretched in the middle of the expansion stroke, and the length will be insufficient. Can prevent malfunctions.

  Furthermore, since the base end side of the dust cover is not fixed to the cylinder side, fixing work is not required, and the assembly cost can be reduced accordingly.

  Hereinafter, an embodiment in which the present invention is embodied in a double-cylinder strut type hydraulic shock absorber for use in an automobile suspension will be described with reference to the drawings. FIG. 1 shows a hydraulic shock absorber mounted on a vehicle body. 1, a knuckle bracket 3 connected to an axle knuckle arm (not shown) is fixed to the outer periphery of the base end of the cylinder 2 (referred to below in FIG. 1) by welding, and the cylinder above the knuckle bracket 3 A lower spring seat 5 as a lower spring guide for supporting the lower end of the suspension spring 4 is fixed to the outer periphery of the suspension spring 4 by welding.

  A synthetic resin bump stopper 7 having a bottomed cylindrical shape is fitted to the opening end portion of the cylinder 2, and the piston rod 8 protrudes from the cylinder 2 through the bump stopper 7. .

  A plurality of protrusions (six in this embodiment as shown in FIG. 2) 9 projecting toward the outer periphery of the cylinder 2 are provided on the outer periphery of the lower end of the bump stopper 7. The protrusion 9 and the bump stopper 7 are integrally formed when the bump stopper 7 is formed by injection molding.

  The protrusion 9 includes an inclined surface 9a as a centering portion of the present invention that expands toward the base end side of the cylinder 2, and a base end portion 15a of a dust cover 15 to be described later when the piston rod 8 is contracted. Is brought into contact with the inclined surface 9a, and the centering action of the dust cover 15 with respect to the cylinder 2 is automatically performed.

  In addition, the inclined surface 9a of the protrusion 9 is formed in an arc surface, and the base end portion 15a of the dust cover 15 is in line contact with the protrusion 9 when the piston rod 8 is contracted. The collision sound at the time of contact is less likely to occur.

  Furthermore, the outer diameter R of the circle formed by connecting the tips of the protrusions 9 is set to be substantially the same as the inner diameter r of the peak portion of the dust cover 15.

  A strut insulator 11 having a fitting for mounting on the vehicle body side is fixed to the tip of the piston rod 8 by a nut 10, and a bump rubber 12 is press-fitted and fixed to the piston rod 8 which is a lower portion of the insulator 11.

  A bearing member 13 made entirely of synthetic resin is fixed to the lower part of the strut insulator 11 on the outer peripheral side of the bump rubber 12, and a synthetic rubber that supports the upper end of the suspension spring 4 is fixed to the lower part of the bearing member 13. Alternatively, an upper spring seat 14 as an upper spring guide made of natural rubber is fitted.

  A mounting portion 16 provided on the front end side of the dust cover 15 is disposed between the bearing member 13 and the bump rubber 12 and is sandwiched between the inner peripheral surface of the bearing member 13 and the outer peripheral surface of the bump rubber 12. It is fixed by positioning.

  The dust cover 15 includes a cylindrical mounting portion 16 sandwiched between the bearing member 13 and the bump rubber 12 and a bellows portion 17 continuously provided downward from the mounting portion 16. In the mounted state, the inner surface of the base end portion 15 a of the dust cover 15 comes into contact with the inclined surface 9 a of the protrusion 9.

  Further, the dust cover 15 has the outer diameter of the peak portion of the bellows portion 17, the inner diameter of the valley portion, the number of peaks, etc. so that the bellows portion 17 of the dust cover 15 is most folded when the piston rod 8 is in the most contracted state. Is set.

  Furthermore, the inner diameter r of the base end portion 15a of the dust cover 15 serving as the base end portion of the bellows portion 17 is set to be substantially the same as the outer diameter R of the protrusion 9 of the bump stopper 7, and the piston rod 8 is In the contraction stroke entering the cylinder 2, the base end portion 15 a of the dust cover 15 is in contact with the inclined surface 9 a of the protrusion 9 of the bump stopper 7 so that it does not move downward below the base end side of the cylinder 2. It has become.

  According to the hydraulic shock absorber configured as described above, in the contraction stroke in which the piston rod 8 enters the cylinder, the dust cover 15 whose tip is attached to the piston rod 8 also moves downward as the piston rod 8 enters. Move to.

  However, since the bump stopper 7 provided at the opening end of the cylinder 2 is provided with a projection 9 having an outer diameter R set to be substantially the same as the inner diameter r of the base end 15a of the dust cover 15, the dust cover 15, the inner surface of the base end portion 15a abuts on the inclined surface 9a of the projection 9, and the downward movement is restricted.

  Therefore, it is possible to prevent the base end portion 15 a from coming into contact with the lower spring sheet 5 positioned below the bump stopper 7, and the coating of the lower spring sheet 5 caused by the base end portion 15 a coming into contact with the lower spring sheet 5 can be prevented. It is possible to prevent the occurrence of rust due to peeling.

  Further, in the extension stroke in which the piston rod 8 is retracted from the cylinder 2, the dust cover 15 having the tip attached to the piston rod 8 is also moved upward as the piston rod 8 is retracted.

  However, since the base end portion of the dust cover 15 is not fixed to the cylinder 2, even a hydraulic shock absorber in which the stroke length of the extension stroke is set longer than the stroke length of the contraction stroke, It is possible to prevent the problem that the bellows portion 17 is stretched halfway and the length is insufficient.

  In particular, as in the present embodiment, the outer diameter of the peak portion, the inner diameter of the valley portion, and the number of peaks of the bellows portion 17 so that the bellows portion 17 of the dust cover 15 is folded most when the piston rod 8 is in the most contracted state. In the case where the above is set, the above-described problem occurs during the extension stroke, and therefore the present invention is effective.

  Further, in the above-described extension stroke, the piston rod 8 may be retracted from the cylinder 2 as the base end portion 15a of the dust cover 15 is separated from the projection 9 depending on the road surface condition or the like.

  In this case, the base end portion 15a of the dust cover 15 comes into contact with the protrusion 9 again when the contraction process is started. However, depending on the road surface condition described above, as shown in FIG. And the axis of the cylinder 2 may be in contact with each other.

  However, since the inclined surface 9a as the aligning portion is formed on the protrusion 9, the base end portion 15a of the dust cover 15 descends according to the inclined surface 9a as shown by the arrow P, so that the dust is The misalignment between the cover 15 and the cylinder 2 is automatically aligned.

  Therefore, it is possible to reliably prevent the misalignment between the dust cover 15 and the cylinder 2 from impairing the smooth operation of the piston rod 8.

  In addition, by forming the inclined surface 9a of the protrusion 9 into an arcuate surface, the base end portion 15a of the dust cover 15 is in line contact with the protrusion 9 during the contraction stroke of the piston rod 8 described above. It is possible to make it difficult to generate a collision sound.

  Further, since the protrusions 9 as the restricting members are provided on the outer periphery of the bump stopper 7 at a predetermined interval, it is possible to prevent the generation of sound when the base end portion 15a of the dust cover 15 contacts the protrusions 9.

  Further, since air can be released when the dust cover 15 is folded after the proximal end portion 15a of the dust cover 15 abuts against the protrusion 9, the smooth operation of the piston rod 8 is not impaired.

  Further, since the base end side of the dust cover 15 is not fixed to the cylinder 2 side as in the prior art, fixing work is not required, and the assembly cost can be reduced accordingly.

  In addition, this invention is not limited to the said embodiment, For example, it can also be changed and embodied as follows.

  (1) In the above-described embodiment, the protrusion 9 as the restricting member is integrally formed with the bump stopper 7, but it may be provided separately and attached to the bump stopper 7.

  (2) In the above embodiment, six protrusions 9 as restricting members are used, but the present invention is not limited to this, and may be four or eight.

  (3) In the above-described embodiment, the protrusion 9 as the restricting member is provided on the outer periphery of the lower end of the bump stopper 7, but is not limited to this portion, and may be the center or upper end of the bump stopper 7.

  (4) In the above-described embodiment, the invention is embodied in the strut type hydraulic shock absorber, but may be embodied in other hydraulic shock absorbers.

  (5) In the above-described embodiment, the present invention is embodied in a double cylinder type hydraulic shock absorber. However, it may naturally be embodied in a single cylinder type hydraulic shock absorber.

It is a partially broken front view showing a strut type hydraulic shock absorber. It is a top view which shows a bump stopper. It is a partially broken front view which shows the case where a bump stopper and a dust cover contact | abut in the state which shifted center.

Explanation of symbols

2 Cylinder 4 Suspension spring 5 Lower spring seat (lower spring guide)
7 Bump stopper 8 Piston rod 9 Projection (regulation member)
9a Inclined surface (alignment part)
12 Bump rubber 15 Dust cover 15a Base end 17 Bellows

Claims (4)

A bump rubber is fixed to the tip side of the piston rod, and a bump stopper that contacts the bump rubber is provided at the cylinder opening end, and arranged on the outer periphery of the piston rod so as to cover the bump rubber, bump stopper, and piston rod. In the hydraulic shock absorber provided with the bellows-shaped dust cover, the tip end of the dust cover is fixed to the tip end side of the piston rod, while the bump stopper is provided with a regulating member with which the base end portion of the dust cover comes into contact with the piston rod. Prevents the base end of the dust cover from moving from the restricting member to the base end of the cylinder during the shrinking stroke, and aligns the dust cover with the cylinder by contacting the base end of the dust cover. A hydraulic shock absorber provided with a centering portion for performing the above. The cylinder is provided with a lower spring guide that supports the lower end of the suspension spring, and an upper spring guide that supports the upper end of the suspension spring is provided on the distal end side of the piston rod, and the restricting member is the base end of the dust cover during the contraction stroke of the piston rod 2. The hydraulic shock absorber according to claim 1, wherein the hydraulic shock absorber is provided at a position where it can be prevented from coming into contact with the lower spring guide. The restricting member is a plurality of protrusions protruding toward the outer circumferential direction of the cylinder, and is formed at predetermined intervals in the circumferential direction of the cylinder, and the diameter of the protrusion increases toward the cylinder base end side. The hydraulic shock absorber according to claim 1 or 2, wherein an inclined surface is formed to constitute an alignment portion. 4. The hydraulic shock absorber according to claim 3, wherein the inclined surface formed on the protrusion is formed as an arc surface, and the dust cover is in contact with the inclined surface in a line contact state.

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