JP2014088931A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the molding process by molding a piston ring in a U-shaped cross section and attaching a flange part formed as a piston support to a groove bottom direction of the piston ring, and to smoothly move a seat pipe by giving deviation in a tolerable range between the piston ring and the flange part.SOLUTION: In a shock absorber including a seat pipe 2, an inner tube 3 to which the seat pipe 2 is coaxially fitted by insertion, and a piston ring 4 attached to the seat pipe 2 and having an outer peripheral surface slid in contact with an inner peripheral surface of the inner tube 3, the piston ring 4 is formed by a cylinder part 4A and upper and lower bent pieces 4B and 4C bent to a seat pipe direction from both ends of the cylinder part 4A, and a flange part 15 protruded to a groove bottom 4D direction between the bent pieces 4B and 4C is formed by deforming a part of the seat pipe 2 to an outer direction.

Description

  The present invention relates to a shock absorber, and more particularly to a shock absorber that absorbs vibrations input to a wheel from a road surface.

Conventionally, a shock absorber is configured such that a piston sliding in a cylinder is fixed to one end of a piston rod, and the piston slides along an axis of the cylinder. A seal member that enables sliding contact with the inner wall of the cylinder is provided between the piston and the cylinder. This seal member is a so-called piston ring, which is formed in an annular shape with a U-shaped cross section, the inner peripheral surface side is in close contact so as to surround the outer peripheral side of the piston, and the outer peripheral surface is in contact with the inner peripheral surface of the cylinder. By being in close contact, it is configured so that no pressure leakage occurs when the piston slides in the cylinder (Patent Document 1).
However, according to this configuration, in order to accurately attach the U-shaped seal member to the piston, it is necessary to perform high-precision processing or the like so that the piston corresponds to the shape of the inner peripheral surface side of the seal member. It has a drawback that the processing work becomes troublesome.
In addition, when operating as a shock absorber suspension, the piston rod that fixes the piston moves up and down along the central axis of the cylinder, but the seal member is in close contact with the outer periphery and both end surfaces of the piston. The center axis of the piston rod may move up and down with an inclination component with respect to the center axis of the cylinder due to bending input due to suspension load or braking load. As a result, galling may occur between the seal member and the inner surface of the cylinder, or stress may be generated between the seal member and the piston to cause the seal member to come off from the piston.

JP-A 63-270933

  In view of this, the present invention forms a seal member as a piston ring in a U-shaped cross section, and a flange portion formed as a piston is mounted in the groove bottom direction of the seal member so that the molding process can be easily performed. Further, the piston ring can be smoothly moved by giving a deviation within an allowable range between the piston ring and the flange portion.

As a configuration of the shock absorber for solving the above-described problem, a seat pipe, an inner tube into which the seat pipe is coaxially inserted, and an outer peripheral surface that is attached to the seat pipe are in sliding contact with an inner peripheral surface of the inner tube. A shock absorber comprising a piston ring, wherein the piston ring is formed by a cylindrical portion and bent portions in the direction of the seat pipe from both ends of the cylindrical portion, and a part of the seat pipe Since the flange part projecting in the groove bottom direction between the bent pieces is formed by deforming the outer side of the pipe, the piston ring is formed from the cylinder part and the bent piece, and the flange part formed on the seat pipe is bent. Since it can be formed simply by fitting into the groove bottom side between the pieces, no special cutting is required, and commercialization is possible only by easy bending.
In addition, as another configuration of the shock absorber for solving the above-mentioned problem, the outer peripheral side of the flange portion is separated from the groove bottom by a certain distance, so that a margin can be given to the movement between the inner tube and the seat pipe. The longitudinal movement of the seat pipe can be performed smoothly.
Further, as another configuration of the shock absorber for solving the above-mentioned problem, since the flange portion is composed of a U-shaped section facing the groove bottom on the outer peripheral side, the flange portion is formed into two layers by the U-shaped body. The strength of itself can be improved.
In addition, as another configuration of the shock absorber for solving the above-mentioned problem, since the flange portion is composed of a single bent plate with the outer peripheral side facing the groove bottom, the structure of the flange portion is simpler. By forming it from a single bent plate, processing becomes easy.
Further, as another configuration of the shock absorber for solving the above-mentioned problem, since the window is formed in the upper side of the cylinder portion of the piston ring and the upper bent piece, oil can be circulated through this window. it can.
Further, as another configuration of the shock absorber for solving the above problem, the flange portion has a gap between the upper and lower bent pieces of the piston ring. Oil can be circulated between the ring and a flow path for obtaining a damping force can be obtained.

It is sectional drawing which shows one Embodiment of the shock absorber by this invention. It is sectional drawing to which the principal part of the shock absorber by this invention was expanded. It is a principal part perspective view of the other form of the shock absorber by this invention. It is operation | movement explanatory drawing of the form shown in FIG.

1 and 2 are cross-sectional views showing an embodiment of a shock absorber according to the present invention.
A shock absorber 1 according to this embodiment is a cylindrical seat pipe 2 having a predetermined length, an inner tube 3 into which the seat pipe 2 is coaxially inserted on the lower side, and attached to the seat pipe 2. Has a piston ring 4 that is in sliding contact with the inner peripheral surface of the inner tube 3, a spring 5 that presses the seat pipe 2, and a spring seat 6.

  In addition, the shock absorber 1 is attached to the outer tube 7 in which the lower side of the inner tube 3 is coaxially inserted, and the inner peripheral surface of the outer tube 7, and allows the inner tube 3 to be slidable. The bearing 8; 9 is stored in an internal space formed by the outer tube 7 and the inner tube 3, and the inner tube 3 and the upper and lower bearings 8; Oil K for obtaining a damping force accompanying the movement and oil K leaks from a gap where the inner tube 3 and the outer tube 7 slide by being attached to one end side of the outer tube 7 by being stopped by a retaining ring 11. An oil seal 12 for preventing the dust and a dust seal 13 for preventing foreign matter from entering the internal space. Further, a top cap 31 that closes one end, a lock collar 32 that is provided on the inner peripheral surface of the other end and slides along the outer peripheral surface of the seat pipe 2 are attached to the inner tube 3. A spring collar 33 that supports the upper end is accommodated.

The piston ring 4 is formed by bending a cylindrical portion 4A having a dividing portion A in the middle and bent pieces 4B and 4C at both ends of the cylindrical portion 4A so as to face the seat pipe 2. The cross-section is U-shaped. In other words, the piston ring 4 is formed into a cylindrical part 4A and bent pieces 4B and 4C as projecting pieces protruding in the axial direction of the cylindrical part 4A from both end edges of the cylindrical part 4A. , 4C is provided with a dividing portion A as a cut continuous from the cylindrical portion 4A.
For example, the dividing portion A is formed as a cut that divides the tubular portion 4A and the two bent pieces 4B and 4C in a state of being inclined with respect to the central axis of the tubular portion 4A. The dividing portion A is formed by fitting the cylindrical portion 4A and the bent pieces 4B and 4C when the flange portion 15 formed in the seat pipe 2 described later is fitted into the groove between the bent pieces 4B and 4C of the piston ring 4. While expanding and facilitating the fitting to the flange portion 15, the ring-shaped expansion and contraction by the dividing portion A stabilizes the close contact with the inner peripheral surface of the inner tube 3. The piston ring 4 is made of, for example, metal or resin.
In this case, a flange portion 15 is formed on the upper end side of the seat pipe 2 so as to project a part of the plate thickness outwardly and project in the groove bottom 4D direction between the bent pieces 4B and 4C. ing. The flange portion 15 is a piston that is surrounded by a concave portion formed by the bent pieces 4B and 4C of the piston ring 4 and the cylindrical portion 4A, and slides along the inner circumferential surface of the inner tube 3 along the axial direction. Forming part. The seat pipe 2 is a cylindrical tubular body, and penetrates the closed end of the outer tube 7 so that the end opposite to the end where the flange portion 15 is formed contacts the bottom of the outer tube 7. The bolt 34 is fixed coaxially with the outer tube 7. Upper and lower oil circulation holes 36 and 37 are formed on the outer peripheral surface of the seat pipe 2 at a predetermined distance from each other in the extending direction and penetrate in the plate thickness direction. By distributing the oil K, the lock collar 32 on the inner peripheral surface side of the inner tube, the outer peripheral surface of the seat pipe 2 and the upper oil chamber R1 defined by the piston ring 4, the inner peripheral surface side of the outer tube 7, A lock collar 32 and a lower oil chamber R2 defined by the outer peripheral surface of the seat pipe 2 are formed, and a damping force is obtained by changing the volumes of both the oil chambers R1 and R2.

The flange portion 15 is formed from a U-shaped section with the outer periphery 15A facing the groove bottom 4D side to form two layers to increase the strength, and the upper and lower end surfaces 15B and 15C are the upper and lower bent pieces 4B, Each abuts 4C.
The flange portion 15 is not limited to a U-shape, and may be formed from a single bent plate that is bent so that the outer periphery 15A side faces the groove bottom 4D.
The flange portion 15 has an outer periphery 15A side spaced apart from the groove bottom 4D by a certain distance, and due to the gap δ between the groove bottom 4D and the outer periphery 15A, the seat pipe 2 is slightly inclined with respect to the inner tube 3. However, since this inclination can be absorbed by the lateral displacement of the seat pipe 2 based on this inclination, the longitudinal movement of the seat pipe 2 can be performed smoothly.

Further, the spring seat 6 for seating the lower end of the spring 5 is seated on the upper end surface 15B of the flange portion 15. The lower end of the bent portion 6B bent in the direction of the end surface 15B above the inner side of the horizontal seating portion 6A of the spring seat 6 is seated on the end surface 15B on the upper side of the flange portion 15, and is folded inward from this seating position. The positioning piece 6D is formed at the tip of the bent horizontal piece 6C, and the outer periphery of the positioning piece 6D is brought into contact with the inner peripheral side of the flange portion 15, whereby the spring seat 6 can be positioned with respect to the seat pipe 2.
In this way, the spring 5 is seated on the flange portion 15 of the seat pipe 2 via the spring seat 6, so that the spring 5 does not directly contact the piston ring 4, so that the movement of the piston ring 4 with respect to the flange portion 15 is ensured. Can do.

In the above configuration, the shock absorber 1 is used as a front fork of a vehicle, for example, a two-wheeled vehicle, the closed end side of the inner tube is fixed to the vehicle body side, and the axle is inserted into the axle through hole 39 provided on the closed end side of the outer tube. By attaching the wheel by penetrating the wheel, it expands and contracts so that the wheel follows the unevenness of the road surface.
When the vehicle travels, the spring 5 interposed between the seat pipe 2 and the inner tube 3 expands and contracts due to the unevenness of the road surface, and the piston ring 4 of the seat pipe 2 moves together with the flange portion 15 inside the inner tube 3. In this configuration, a damping force is obtained by moving the peripheral surface up and down. In such an expansion / contraction motion, the inner tube 3 is subjected to fine bending (bending) with the upper and lower bearings 8; 9 as fulcrums. This bending of the inner tube 3 means that the axis of the inner tube 3 is inclined or misaligned with respect to the axis of the seat pipe 2, but there is a gap δ between the flange portion 15 of the seat pipe 2 and the piston ring 4. Is set, the inclination and deviation are absorbed by the gap δ.

According to the present embodiment, even if the seat pipe 2 is moved up and down while being pressed by the spring 5, the force in the vertical direction is transmitted to the piston ring 4 through the flange portion 15. Slides on the inner peripheral surface of the inner tube 3 and the seat pipe 2 moves up and down smoothly. In particular, since the outer periphery 15A of the flange portion 15 is separated from the groove bottom 4D by a certain distance, even when the seat pipe 2 is slightly inclined with respect to the inner tube 3, the gap between the groove bottom 4D and the outer periphery 15A Since δ can absorb the lateral displacement of the seat pipe 2 based on this inclination, the longitudinal movement of the seat pipe 2 can be performed smoothly.
Further, since the flange portion 15 can be formed by bulging a part of the plate thickness of the seat pipe 2 in the outward direction, the manufacturing becomes easy and high-precision manufacturing is possible.

Other Embodiments FIG. 3 is a perspective view of a main part for explaining another embodiment of the shock absorber 1 according to the present invention, and FIGS. 4 (a) and 4 (b) are diagrams for explaining the operation thereof.
In each figure, the piston ring 4 includes a cylindrical portion 4A, a lower bent piece 4C bent in the direction of the seat pipe 2 from the end opposite to the spring 5 of the cylindrical portion 4A, and the groove bottom 4D. A plurality of projecting pieces 20 projecting from the outer peripheral edge on the spring 5 side at a predetermined interval are formed. In the present embodiment, the number of the protruding pieces 20 is four, but the number of the protruding pieces 20 is not limited to this, and may be appropriately formed at equal intervals along the circumferential direction of the piston ring 4.
A claw portion 20A bent at a right angle inward is formed on the tip side of the protruding piece 20, and the upper end surface 15B of the flange portion 15 is in contact with the claw portion 20A. The oil K injected into the shock absorber can be circulated through the window M formed by the interval. The claw portion 20A corresponds to the bent piece 4B in the above embodiment.
Further, a gap R is formed between the claw portion 20 </ b> A of the piston ring 4 and the upper end surface 15 </ b> B of the flange portion 15.

According to the above configuration, when the shock absorber is extended, as shown in FIG. 4A, the inner tube 3 moves to the spring 5 side, so that the bent piece 4C becomes the lower end face 15C of the flange portion 15. Is brought into contact with the oil to seal the flow of the oil K indicated by the arrow in FIG.
Further, when the shock absorber is compressed, as shown in FIG. 4B, the inner tube 3 moves to the seat pipe 2 side, so that the claw portion 20A of the piston ring 4 contacts the upper end surface 15B of the flange portion 15. By doing so, the oil K flows from the window M between the protruding pieces 20 as indicated by the arrows in the figure, and a damping force different from the damping force at the time of expansion can be generated at the time of compression.
That is, even after the piston ring 4 has moved relative to the flange portion 15 by the gap R, a flow path through which the oil K flows during compression can be formed by securing the oil flow path with the window M between the claws 20A. Further, the movement of the piston ring 4 can provide a function as a check valve for controlling the flow of the oil K flowing around the flange portion 15.

The above-described shock absorber is configured as a front fork of a motorcycle, and the front fork of the motorcycle can be configured by attaching the front fork to the left and right sides of the axle of the motorcycle and the vehicle body.
Further, when the shock absorber according to the present invention is applied to the front fork of a motorcycle, the above embodiment has been described as including the spring 5 in the shock absorber. However, the spring 5 may be provided separately from the shock absorber. . That is, the spring 5 is excluded from the shock absorber of the present invention to form a shock absorber having a damping function configuration, and this shock absorber is applied to either the left or right front fork. In this case, the spring seat 6 becomes unnecessary. Further, as the other front fork, a front suspension of a motorcycle may be configured using a front fork having a suspension function configuration using a spring.

1 shock absorber, 2 seat pipe, 3 inner tube,
4 piston ring, 5 spring, 6 spring seat, 15 flange,
δ Clearance.

Claims (6)

In a shock absorber comprising a seat pipe, an inner tube into which the seat pipe is fitted coaxially, and a piston ring attached to the seat pipe and having an outer peripheral surface slidably contacting the inner peripheral surface of the inner tube,
The above-mentioned piston ring is formed by a cylindrical portion and upper and lower bent pieces which are bent in the seat pipe direction from both ends of the cylindrical portion,
A shock absorber, wherein a part of the seat pipe is deformed outward to form a flange portion protruding in the groove bottom direction between the bent pieces.   2. The shock absorber according to claim 1, wherein the flange portion is spaced apart from the groove bottom by a constant distance.   The shock absorber according to claim 1 or 2, wherein the flange portion is formed of a U-shaped section whose outer peripheral side faces the groove bottom.   The shock absorber according to claim 1 or 2, wherein the flange portion is composed of a single bent plate bent so that the outer peripheral side faces the groove bottom.   The shock absorber according to any one of claims 1 to 4, wherein a window is formed in an upper side and an upper bent piece of the cylindrical portion of the piston ring. The shock absorber according to any one of claims 1 to 5, wherein the flange portion has a gap between the upper and lower bent pieces of the piston ring.

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