JP5653405B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber such as a front fork of a motorcycle.

  Conventionally, an outer tube, an inner tube, and a seat pipe formed by a cylinder are provided, and the inner tube is inserted into the outer tube from one end opening side through one end opening of the outer tube, and the inner tube and the outer tube Are configured to be movable in the direction along the central axis of the cylinder, the oil is enclosed inside the outer tube, and one end of the cylinder of the seat pipe is attached to the bottom of the other end of the closed outer tube. In the front fork as a shock absorber, the seat pipe is provided with an enlarged diameter portion on the other end side of the cylinder inserted into the inner tube from one end opening of the inner tube so that the piston ring surrounds the outer periphery of the enlarged diameter portion. The piston part is configured by being attached to the enlarged diameter part, and the inner tube follows the central axis. Configuration front fork of the outer peripheral surface of the piston ring of the inner peripheral surface and the piston portion of the inner tube is configured to slide relative to each other when moving in the direction is known (see Patent Document 1).

Japanese Patent Publication No.3-331944

However, in the above, since the piston portion is configured to include the piston ring, the number of parts constituting the piston portion increases, and the annular recess for mounting the piston ring on the outer peripheral surface of the enlarged diameter portion of the seat pipe There is a problem that the manufacturing cost of the piston portion becomes high.
The present invention provides a shock absorber capable of reducing the cost of a piston portion.

The shock absorber according to the present invention includes an outer tube, an inner tube, and a seat pipe formed by a cylinder, and the inner tube is inserted from one end opening side into the outer tube through one end opening of the outer tube. The inner tube and the outer tube are configured to be movable in a direction along the central axis of the cylinder, oil is sealed inside the outer tube, and the seat pipe is connected to the inner tube from one end opening of the inner tube. One end side of the cylinder inserted inside the inner tube is provided with an enlarged diameter portion, and the other end of the cylinder is arranged so that the seat pipe can move in a direction intersecting the central axis of the cylinder of the outer tube. The other end of the closed cylinder is attached to the bottom of the cylinder, and the outer periphery of the enlarged diameter portion and the inner An oil flow path that generates a damping force for attenuating the movement of the inner tube and the outer tube is formed by a gap between the inner peripheral surface of the tube and the number of parts constituting the piston portion. Since it is not necessary to form an annular recess for mounting the piston ring on the outer peripheral surface of the enlarged diameter portion of the seat pipe, the cost of the piston portion can be reduced and the seat pipe collapses. When the front fork is bent due to the travel input, the other end of the seat pipe can move in a direction intersecting the central axis of the cylinder of the outer tube, and the frictional force applied to the member forming the oil flow path can be reduced. . Further, since the oil passage is formed, a damping force can be obtained by the oil passage.
Further, a collar formed by the cylinder is fixed coaxially to the inner peripheral surface on the one end opening side of the inner tube, and between the outer peripheral surface of the cylinder of the seat pipe and the inner peripheral surface of the collar. Since the oil flow path for generating a damping force for attenuating the movement of the inner tube and the outer tube is formed by the gap, the damping force can be obtained by the oil flow path .

Sectional drawing of a front fork. The expanded sectional view which expanded the seat pipe of the front fork, and its vicinity.

  Hereinafter, the present invention will be described in detail through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included in the invention. It is not necessarily essential to the solution, but includes a configuration that is selectively adopted.

A front fork 50 of a motorcycle as an example of a shock absorber according to an embodiment will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the front fork 50 includes an outer tube 30, an inner tube 51, and a seat pipe 41 formed of, for example, a metal cylinder, and the inner tube 51 is connected to the outer tube 30 from one end opening 52 side of the cylinder. One end opening 32 of the cylinder and the bearing 8A; inserted into the outer tube 30 via the bearing 8B, the inner tube 51 and the outer tube 30 are configured to be movable in the direction along the central axis 3A of the cylinder, respectively. The That is, the inner tube 51 and the outer tube 30 are arranged coaxially so that the center axis 3A of the cylinder coincides, and are configured to be movable in a direction along the center axis 3A.

A bearing press-fit portion 72A is formed on the inner peripheral surface 31 near the one end opening 32 of the outer tube 30 and the inner peripheral surface 31 between the bearing press-fit portion 72A and the other end cylinder bottom 39 of the outer tube 30 also A bearing press-fit portion 72B different from the bearing press-fit portion 72A is provided. The bearing 8A; the bearing 8B is inserted into the outer tube 30 from the one end opening 32 side of the outer tube 30, and is inserted into each bearing press-fit portion 72A; 72B. It is press-fitted and fixed. That is, the inner tube 51 is inserted from the one end opening 52 side into the outer tube 30 via the bearing 8A; the bearing 8B fixed to the one end opening 32 of the outer tube 30 and the inner peripheral surface 31 of the outer tube 30; The bearing 8A is supported by the bearing 8B and is configured to be movable in a direction along the central axis 3A of the cylinder of the outer tube 30.
1 is fixed to the inner peripheral surface 31 of the outer tube 30 in the vicinity of the one end opening 32 of the outer tube 30, and the lower bearing 8B in FIG. 1 is the inner tube 51 when the front fork 50 is fully extended. The one end opening 52 side of the outer tube 30 is fixed to the inner peripheral surface 31 of the outer tube 30 located on the one end opening 32 side of the outer tube 30 side. In other words, the upper bearing 8A and the lower bearing 8B are provided at positions that overlap the inner tube 51 when the front fork 50 is fully extended.

  A bottomed tool insertion hole 36 extending from the other end outer surface 35 toward the one end opening 32 side is formed at the other end of the outer tube 30, and a through hole 37 with or without an internal thread is formed as a tool insertion hole 36. Are formed so as to communicate with the fitting recess 15 formed on the bottom surface 39 of the outer tube 30 and the bottom 39 of the other end of the outer tube 30. Each hole is formed so that the center axis 3A of the cylindrical hole of the outer tube 30, the center axis 3A of the tool insertion hole 36, the center axis 3A of the through hole 37, and the center axis 3A of the fitting recess 15 coincide. An axle through hole 40 is formed at the other end of the outer tube 30. The axle through hole 40 is formed by a through hole whose center axis is perpendicular to the center axis 3 </ b> A of the cylindrical hole of the outer tube 30, passes through the tool insertion hole 36, and both ends open on the outer peripheral surface of the other end of the outer tube 30. Is done.

A seat pipe 41 is installed in the cylinder of the outer tube 30.
One end side of the seat pipe 41 is inserted into the inner tube 51 via the one end opening 52 of the inner tube 51, and the seat pipe 41 can move in a direction intersecting the central axis 3 </ b> A of the cylinder of the outer tube 30. In this way, the other end of the cylinder is formed by a cylinder attached to the other end cylinder bottom 39 of the outer tube 30 closed via the attachment device 10.

As shown in FIG. 2, the attachment device 10 is configured by a nut-like component including a female screw portion 11 to which a fixing bolt 42 is screwed. The nut-like component constituting the attachment device 10 is formed at a cylindrical seat pipe support portion 12 having one end portion in the direction along the central axis of the female screw portion 11 as the central axis line. The other end in the direction along the central axis of the inner thread is formed in a cylindrical fitting portion 13 having a cross section (cross section orthogonal to the central axis) having the central axis of the female screw portion 11 as the central axis. The engaging recess 14 is formed on the outer peripheral surface of the central portion in the direction along the central axis of the female screw portion 11 by an annular groove having the central axis of the female screw portion 11 as the central axis.
The fitting recess 15 has a polygonal cross section (cross section orthogonal to the central axis) having a central axis 3A into which the cylindrical fitting portion 13 such as a polygonal or circular cross section of the attachment device 10 is fitted. Alternatively, it is formed in a circular recess or the like. The fitting recess 15 is formed in a recess having one end in the direction along the center axis opened in the other tube bottom 39 of the outer tube 30 and a bottom at the other end in the direction along the center axis. One end of the through hole 37 is open at the bottom of the other end.

The seat pipe 41 is provided with an enlarged diameter portion 1 which is formed on the one end side of the cylinder so as to be larger than the outer diameter of the cylinder and constitutes a piston portion, and on the other end side of the cylinder. The engaging part 2 provided so that it may approach may be provided.
For example, the enlarged diameter portion 1 is formed in an annular shape formed by crushing one end portion of a cylinder constituting the original shape of the seat pipe 41 by press molding or the like, and is formed in an annular shape as shown in FIG. 2 as an example. .
For example, the engaging portion 2 is configured in an annular shape formed by bending the other end portion of the cylinder constituting the original shape of the seat pipe 41 inside the cylinder by press molding or the like, and as an example, as shown in FIG. The other end portion is formed in an annular shape formed by folding back inside the tube, or the other end portion of the tube is formed in an annular shape formed by bending in a direction approaching the central axis of the tube.

Based on FIG. 2, the dimensional relationship of each part is demonstrated.
The outer diameter dimension a1 of the center part of the cylinder of the seat pipe 41 <the outer diameter dimension a2 of the enlarged diameter part 1 at one end of the seat pipe 41 <the inner diameter dimension a3 of the cylinder of the inner tube 51.
The inner diameter dimension b1 of the engaging portion 2 of the seat pipe 41 <the inner diameter dimension b2 of the center portion of the cylinder of the seat pipe 41 ≦ the inner diameter dimension b3 of the enlarged diameter portion 1 at one end of the seat pipe 41.
The diameter dimension c1 of the cylindrical portion having the groove bottom of the engaging recess 14 of the attachment device 10 as the outer peripheral surface <the diameter dimension c2 of the fitting portion 13 of the attachment device 10 <the cylinder forming the seat pipe support portion 12 of the attachment device 10 It is the diameter dimension c3.
The diameter dimension c3 of the cylinder forming the seat pipe support portion 12 of the attachment device 10> the inner diameter size b1 of the engagement portion 2 of the seat pipe 41 ≧ the diameter size c2 of the fitting portion 13 of the attachment device 10.
The length d1 in the direction along the central axis of the engaging portion 2 of the seat pipe 41 is smaller than the length d2 in the direction along the central axis of the engaging recess 14 of the attachment device 10.

  Therefore, the attachment device 10 is inserted into the seat pipe 41 from the enlarged diameter portion 1 side of one end of the seat pipe 41 from the fitting portion 13 side, and the fitting portion 13 of the attachment device 10 is inserted into the engagement portion 2 of the seat pipe 41. The engagement portion 2 of the seat pipe 41 is engaged with the engagement recess 14 of the attachment device 10 through the inside and protruding from the other end of the seat pipe 41. Then, with the fitting portion 13 of the attachment device 10 fitted in the fitting recess 15, the male screw portion of the fixing bolt 42 is inserted into the through hole 37 and the female screw portion 11 of the attachment device 10 and fastened. Since the apparatus 10 is fixed to the fitting recess 15 in the other end cylinder bottom 39 of the outer tube 30, the seat pipe 41 can move in a direction in which the seat pipe 41 intersects the central axis 3 </ b> A of the cylinder of the outer tube 30. The other end of the cylinder is attached by the attachment device 10 to the other end cylinder bottom 39 of the outer tube 30 closed. That is, between the outer peripheral surface of the seat pipe support portion 12 of the attachment device 10 and the inner peripheral surface of the inner tube 51, and between the groove bottom of the engagement recess 14 of the attachment device 10 and the engagement portion 2 of the seat pipe 41. The seat pipe 41 is attached in a state where a gap necessary for moving the seat pipe 41 in the radial direction of the outer tube 30 is provided between the peripheral surface and the peripheral surface. In addition, when the fitting part 13 and the engagement recessed part 15 are formed in cross-sectional polygonal shape, since it functions as a rotation stop at the time of fastening the fixing bolt 42 to the internal thread part 11 of the attachment apparatus 10, the fixing bolt 42 The operation of fastening the bolt and the operation of loosening the fixing bolt 42 can be performed easily and reliably. In addition, in order to have a loosening prevention effect and a sealing effect of the fixing bolt 42, a washer 42 a is preferably interposed between the head of the fixing bolt 42 and the bottom surface 38 of the tool insertion hole 36.

  Since the seat pipe 41 is attached to the other end cylinder bottom 39 of the outer tube 30 by the attachment device 10, the clearance between the outer peripheral surface of the enlarged diameter portion 1 of the seat pipe 41 and the inner peripheral surface 59 of the inner tube 51 is increased. A throttle channel B is formed as a channel for oil (fork oil 48) that generates a damping force for attenuating the movement of the inner tube 51 and the outer tube 30. The gap between the outer peripheral surface of the enlarged diameter portion 1 of the seat pipe 41 and the inner peripheral surface 59 of the inner tube 51 is, for example, about 0.1 mm to 0.15 mm.

A collar 49 formed of a cylinder is fixed to the inner peripheral surface 59 on the one end opening 52 side of the inner tube 51 coaxially with the inner tube 51, and the outer peripheral surface of the cylinder of the seat pipe 41 and the inner peripheral surface of the collar 49. A narrowing channel A as a channel for oil (fork oil 48) that generates a damping force for attenuating the movement of the inner tube 51 and the outer tube 30 is formed by the gap therebetween. The gap between the outer peripheral surface of the cylinder of the seat pipe 41 and the inner peripheral surface of the collar 49 is formed to be about 0.1 mm to 0.15 mm, for example.
Since the inner diameter dimension of the collar 49 is smaller than the outer diameter dimension a2 of the enlarged diameter portion 1 at one end of the seat pipe 41, the collar 49 has the inner diameter of the seat pipe 41 when the front fork 50 is extended. It functions as a stopper that prevents the tube 51 from coming off.

As shown in FIG. 1, fork oil (oil) 48 is accommodated in the cylinder of the outer tube 30, and the cylinder of the inner tube 51 inserted into the outer tube 30 serves as a reservoir chamber 64 that is an oil reservoir. 48A is an oil surface.
An oil seal 60 is attached to the inner surface of the outer tube 30 on the one end opening 32 side, and a dust seal 61 is provided for preventing dust and the like from entering the cylinder of the outer tube 30 from the outside.

  A screw portion 54 is formed on the inner surface of the other end opening 53 of the inner tube 51, and a top cap 55, which is a screw lid, is attached to the screw portion 54 to close the other end opening 53 of the inner tube 51. The other end surface of the top cap 55 is used for inserting a tool for fastening a threaded portion formed on the outer peripheral surface of the top cap 55 to the threaded portion 54 of the inner tube 51 or for attaching the body to a vehicle body not shown. A hole 56 is formed.

A lower oil chamber 62 is formed between the one end opening 52 of the inner tube 51 and the other end cylinder bottom 39 of the cylinder hole located on the other end side of the outer tube 30. An oil chamber 63 is formed.
Accordingly, when the inner tube 51 and the outer tube 30 are moved in the direction along the central axis 3A of the cylinder (when the front fork 50 is extended and contracted), the fork oil 48 flows through the throttle channels A and B. Damping force is obtained by resistance.
When the front fork 50 is compressed, the fork oil 48 passes through the throttle passage A formed by the gap between the lower oil chamber 62 and the inner peripheral surface of the collar 49 and the outer peripheral surface of the seat pipe 41. Damping force is obtained by the resistance when moving to the fork oil 48, and the fork oil 48 is formed by a gap between the outer peripheral surface of the enlarged diameter portion 1 of the seat pipe 41 and the inner peripheral surface 59 of the inner tube 51 from the reservoir chamber 64. A damping force is obtained by the resistance when moving to the upper oil chamber 63 via the throttle channel B.
When the front fork 50 is extended, a damping force is obtained by resistance when the fork oil 48 moves from the upper oil chamber 63 to the lower oil chamber 62 via the throttle channel A, and the fork oil 48 is allowed to move to the upper oil chamber 63. The damping force is obtained by the resistance when moving from the flow path to the reservoir chamber 64 via the throttle channel B.

  The front fork 50 having the damping function configuration described above is also used as one front fork of the left and right front forks of the motorcycle axle, and the front fork of the spring suspension function is used as the other front fork of the left and right front forks. By using it, a front suspension of a motorcycle can be configured.

According to the embodiment, the inner tube 51 and the outer tube 30 formed by a gap between the outer peripheral surface of the enlarged diameter portion 1 of the seat pipe 41 and the inner peripheral surface of the inner tube 51 without using a piston ring. Since the throttle channel B as the channel of the fork oil 48 that generates a damping force for damping the motion is provided, the number of parts constituting the piston can be reduced, and the diameter-enlarged part of the seat pipe 41 Since it is not necessary to form an annular recess for mounting the piston ring on the outer peripheral surface of 1, the cost of the piston portion can be reduced.
Further, the cylinder pipe wall of the seat pipe 41 is attenuated by the throttle channel B without forming an oil flow hole as an oil channel for generating a damping force for attenuating the movement of the inner tube 51 and the outer tube 30. Since the force can be obtained, it is possible to reduce the processing labor for forming the oil circulation hole in the cylindrical wall of the seat pipe 41, and to reduce the cost.
A collar 49 formed of a cylinder is fixed to the inner peripheral surface of the inner tube 51 on the one end opening 52 side coaxially with the inner tube 51, and the outer peripheral surface of the cylinder of the seat pipe 41 and the inner peripheral surface of the collar 49 are Since there is a throttle channel A as an oil channel that generates a damping force for attenuating the movement of the inner tube 51 and the outer tube 30 formed by the gap between the throttle channel B and A damping force can be obtained by the throttle channel A. Accordingly, it is possible to reduce the processing labor for forming the oil circulation holes in the cylindrical wall of the seat pipe 41, and it is possible to further reduce the cost.
Further, in the configuration in which the throttle channel B and the throttle channel A are provided, it is necessary to reduce the gap for forming the throttle channel B and the gap for forming the throttle channel A. In this configuration, the seat pipe When the front fork 50 is bent due to the tilting of 41 or the travel input, strong friction is generated between the outer peripheral surface of the enlarged diameter portion 1 of the seat pipe 41 and the inner peripheral surface 59 of the inner tube 51 forming the throttle channel B. There is a possibility that a strong frictional force may be applied to the inner peripheral surface of the collar 49 and the outer peripheral surface of the seat pipe 41 forming the throttle channel A. Therefore, in the embodiment, the other end of the cylinder is connected to the other end cylinder bottom 39 of the outer tube 30 via the attachment device 10 so that the seat pipe 41 can move in a direction intersecting the central axis 3A of the outer tube 30. Therefore, when the seat fork 41 is tilted or the front fork 50 is bent due to a travel input, the other end of the seat pipe 41 crosses the central axis 3A of the cylinder of the outer tube 30. Since it can move, the frictional force applied to both by the contact between the seat pipe 41 and the inner tube 51 can be reduced. That is, the frictional force caused by the contact between the outer peripheral surface of the enlarged diameter portion 1 on one end side of the seat pipe 41 constituting the throttle channel B and the inner peripheral surface of the inner tube 51, and the outer peripheral surface of the cylinder of the seat pipe 41 and the collar The frictional force due to contact with the inner peripheral surface of 49 can be reduced.
Further, the other end of the cylinder is attached to the other end cylinder bottom 39 of the outer tube 30 via the attachment device 10 so that the seat pipe 41 can move in a direction intersecting the central axis 3A of the outer tube 30. Therefore, when the seat pipe 41 is tilted or the front fork 50 is bent due to traveling input, the centering action of returning so that the center axis of the seat pipe 41 and the center axis of the inner tube 51 coincide with each other works. Since the annular throttle channel A; B around the central axis of the seat pipe 41 and the central axis of the inner tube 51 is adjusted, the damping force obtained by the throttle channel A; B is adjusted. Variations can be suppressed.
As shown in FIG. 1; FIG. 2, the other end surface of the engagement portion 2 of the seat pipe 41 facing the closed other end cylinder bottom 39 of the outer tube 30 protrudes toward the other end cylinder bottom 39 and curves. If the curved surface is formed, the seat pipe 41 can easily rotate with the curved surface as a fulcrum, so that the seat pipe 41 can move in the radial direction of the cylinder of the outer tube 30 even when the seat pipe 41 is tilted. The frictional force applied to both the inner tube 51 and the inner tube 51 can be further reduced.

  In addition, according to the embodiment, the front fork 50 having the configuration in which the two bearings 8A and 8B are fixed to the inner peripheral surface 31 of the outer tube 30 has been described. A front fork having a configuration in which two or more bearings are fixed may be used. Further, a front fork having a configuration in which a bearing is fixed to the outer peripheral surface of the inner tube 51 may be used.

Alternatively, an oil circulation hole may be formed in the cylindrical wall of the seat pipe 41 so that the oil circulation hole functions as an oil flow path that generates a damping force for attenuating the movement of the inner tube 51 and the outer tube 30. Good.
For example, as shown in FIG. 1, an oil circulation hole 45 for circulating fork oil 48 inside and outside the cylinder is formed in the cylinder wall on the other end side of the seat pipe 41, and the oil circulation hole 45 is connected to the inner tube. The collar 49 may function as a lock collar that closes the oil circulation hole 45 while functioning as an oil flow path that generates a damping force for attenuating the movement of the outer tube 30 and the outer tube 30. In this case, when the front fork 50 is compressed, the lock collar blocks the oil circulation hole 45 on the other end side of the seat pipe 41, thereby preventing a collision between one end of the inner tube 51 and the other end bottom 39 of the outer tube 30. The
In addition, oil circulation holes for circulating the fork oil 48 inside and outside the cylinder are formed in the cylinder walls on one end side and the other end side of the seat pipe 41, respectively, and the collar 49 is used as a lock collar for closing these oil circulation holes. May function. In this case, when the front fork 50 is compressed, the lock collar blocks the oil circulation hole 45 on the other end side of the seat pipe 41, thereby preventing a collision between one end of the inner tube 51 and the other end bottom 39 of the outer tube 30. When the front fork 50 is extended, the lock collar closes an oil circulation hole (not shown) on one end side of the seat pipe 41 so that the lock collar and the diameter-enlarged portion 1 of the seat pipe 41 are prevented from colliding.

  Further, instead of the collar 49, a valve device may be provided.

  In the embodiment, the upright front fork 50 has been described as an example, but the present invention is applicable to an inverted front fork.

  The shock absorber of the present invention can be used for a rear suspension of a motorcycle and other shock absorbers.

1 Expanded portion of seat pipe, 3A central axis, 8A; 8B bearing,
30 outer tube, 31 inner peripheral surface of outer tube,
32, one end opening of the outer tube, 39 the other end cylinder bottom of the outer tube,
41 seat pipe, 48 fork oil (oil), 49 color,
51 inner tube, 52 one end opening of inner tube,
59 Inner peripheral surface of inner tube, A: B Restricted flow path (oil flow path).

Claims (2)

Equipped with an outer tube, inner tube, seat pipe formed by a cylinder,
The inner tube is inserted from the one end opening side into the outer tube through the one end opening of the outer tube so that the inner tube and the outer tube can move in a direction along the central axis of the cylinder. And
Oil is enclosed inside the outer tube,
The seat pipe is provided with an enlarged-diameter portion on one end side of the cylinder inserted inside the inner tube from one end opening of the inner tube, and the seat pipe moves in a direction intersecting the central axis of the cylinder of the outer tube. The other end of the cylinder is attached to the closed other end cylinder bottom of the outer tube so as to be possible ,
An oil flow path for generating a damping force for attenuating the movement of the inner tube and the outer tube is formed by a gap between the outer periphery of the enlarged diameter portion and the inner peripheral surface of the inner tube. A shock absorber characterized. A collar formed by a cylinder is fixed coaxially to the inner peripheral surface of the inner tube on the one end opening side, and is formed by a gap between the outer peripheral surface of the cylinder of the seat pipe and the inner peripheral surface of the collar. The shock absorber according to claim 1, wherein an oil flow path for generating a damping force for attenuating movement of the inner tube and the outer tube is formed .

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