JPH01202593A - Front fork for motorcycle - Google Patents

Abstract

PURPOSE:To prevent a subrod from protruding from an outer tube mutually interfering with the other part and a dust or the like from infiltrating by forming the subrod so as to be stored in its most compressed condition into the outer tube. CONSTITUTION:In the case of an inverted type front fork, a hollow piston rod 15 and a subrod 32 are coaxially connected to both sides of a piston 26. A cylinder 7 is mounted to a bottom end part of a subcylinder 4 mounting its upper end part to an outer tube 1. Here because each part is formed in a length such that the subrod 32 is stored in its most compressed condition into the outer tube 1, the subrod 32 is prevented from protruding from the outer tube 1 interfering with the other member in the upper.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a front fork for a motorcycle.

(Prior art) As a front fork used for a motorcycle, for example, as described in Japanese Patent Publication No. 57-49431, a cylindrical fork pipe is installed in a completely cylindrical bottom case penetrated in the axial direction. is slidably inserted to form a damping force generation chamber sealed in the axial direction between the bottom case and the fork pipe, and a piston is attached to the outer periphery of the fork pipe that slides into contact with the inner circumferential surface of the bottom case. It is known that a piston moves within a damping force generating chamber as a fork pipe moves, thereby generating a damping force.

(Problem to be solved by the invention) In the above-mentioned front fork, since the fork pipe is always inside the bottom case, the volume of the damping force generation chamber inside the bottom case does not change due to movement of the fork pipe. However, the fork pipe protrudes from the bottom case and interferes with other members, and dust and the like easily enter the bottom case when retracted.

(Means for Solving the Problems) In order to solve the above problems, the invention of claim 1 provides an inverted front fork in which a piston rod and a sub-rod are coaxially connected on both sides of the piston, and the cylinder is connected to an outer tube. The upper end was attached to the lower end of the attached sub-cylinder, so that the sub-rod was housed in the outer tube in the most compressed state.

Further, the invention of claim 2 provides an upright front fork, in which sub-rods are connected to both sides of the piston on the opposite side to the piston rod, and the cylinder is attached to the lower end of the sub-cylinder whose upper end is attached to the fork pipe. This allows the sub-rod to be stored in the fork pipe in its most compressed state.

(Function) The sub-rod connected to the piston coaxially with the piston rod is housed in the outer tube or fork pipe in the most compressed state, so it does not protrude from the outer tube or fork pipe and interfere with other members or allow dust etc. to enter. There's nothing left to do.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a half-sectional view of an inverted front fork according to the present invention, FIG. 2 is an enlarged sectional view of essential parts of the front fork,
FIG. 3 is a perspective view of the oil seal holder of the front fork, and FIG. 4 is a plan sectional view of the main parts of the front fork.

In this front fork, an inner tube 2 is slidably inserted into an outer tube 1 from below. The upper end of a sub-cylinder 4 consisting of an outer sub-cylinder 5 and an inner sub-cylinder 6 is attached to the upper end of the outer tube 1 and is suspended inside the inner tube 2, and the lower end of the outer sub-cylinder 5 constituting this sub-cylinder 4 The upper end of the cylinder 7 is attached to the inner peripheral surface of the cylinder 7 so as to face inside the inner tube 2.

At the upper end of the inner tube 2, there is an oil hole l that communicates between the inside and outside.
An axle mounting bracket 11 is screwed onto the outer circumferential surface of the lower end of the inner tube 2, and an oil lock piece 12 is fitted onto the inner circumferential surface of the lower end of the inner tube 2 and the inner circumferential surface of the bracket 11. The lower end of a hollow piston rod 15, which is a piston rod, is screwed into the center of the oil lock piece 12 and fixed with a pot nut 16 so as to face inside the cylinder 7.

A rod guide 17 and an oil seal 18 are fitted to the lower end of the cylinder 7 so as to be in sliding contact with the outer peripheral surface of the hollow piston rod 15, and an oil lock collar 19 is attached to the outer periphery of the rod guide 17. Further, a spring receiver 21 is provided on the outer peripheral surface of the intermediate portion of the cylinder 7, and a suspension spring 22 is interposed between the lower surface of the spring receiver 21 and the upper end surface of the oil lock piece 12. A return spring 23 is mounted.

A piece 25 is attached to the tip of the hollow piston rod 15, and a piston 26 that slides on the inner circumferential surface of the cylinder 7 is fitted to the outer circumference of the piece 25, so that the inside of the cylinder 7 is connected to the oil chamber St.
and an oil chamber S2, further forming a compression side oil passage 27 and an extension side oil passage 28 in the piston 26, and a compression side valve for opening and closing these compression side oil passage 27 and extension side oil passage 28. 2
9 and the extension side valve 30 are installed. Then, a piece 31 is screwed onto the upper end of the piece 25, and this piece 3
1 is equipped with a hollow sub-rod 32 having the same diameter as the hollow piston rod 15, and has a double-rod structure in which the hollow piston rod 15 and the hollow sub-rod 32 are coaxially connected on both sides of the piston 26.

In this case, outer tube 1, inner tube 2,
Sub cylinder 4, cylinder 7, hollow piston rod 15
The hollow sub-rods 32 and the like are formed to have such a length that the upper end of the sub-rod 32 does not protrude from the upper end of the outer tube l when in the most compressed state in one dimension.

In addition, a valve pressing member 35 that contacts the back surface of the compression side valve 29 of the piston 26 is fitted into the outer periphery of the piece 25 on the lower side of the piston 26 so as to be able to move up and down. A spring seat support member 37 is fitted into the notch 14 so as to be able to rise and fall freely, and a spring seat 38 is engaged with the outer edge of the spring seat support member 37. A compression spring 39 is interposed between the valve pressing member 35 and the valve pressing member 35 to form a damping force adjustment mechanism that adjusts the damping force by changing the preset load of the valve pressing member 35.

A bushing rod 41 is screwed into the upper end of the hollow piston rod 15 so that it can move forward and backward, and a spring seat support member 37 is fixed to the upper end of the bushing rod 41. As shown in FIG. 4, the upper end of an operating pipe 42 having a substantially half-moon cross section is fitted in an odd shape, an adjuster 43 is fitted in an odd shape to the lower end of this operating pipe 42, and the adjuster 43 is rotated. It serves as an operating mechanism for advancing and retracting the four bush rods.

Furthermore, a bypass oil passage 45 is formed inside the piece 25 and communicates with the oil chamber S2 in the axial direction, and the piece 31 forms an oil passage 46 that communicates the bypass oil passage 45 with the oil chamber S1. A needle 47 is screwed into the hollow sub-rod 32 so that it can move forward and backward, and the tip of the needle 47 faces the opening 0 of the upper end of the bypass oil passage 45 of the piece 25, thereby controlling the opening amount of the bypass oil passage 45. This is a damping force adjustment mechanism that adjusts the damping force by changing the damping force.

The upper end of the needle 47 is fitted with the lower end of an operating pipe 48 similar to the operating pipe 42 shown in FIG. Rotating the adjuster 49 serves as an operating mechanism for moving the needle 47 forward and backward.

The upper end of the outer sub-cylinder 5 of the sub-cylinder 4 is screwed onto the inner peripheral surface of the upper end of the outer tube 1, and a fork pole 51 is screwed onto the inner peripheral surface of the upper end of this outer sub-cylinder 5.
By screwing the upper end of the inner sub-cylinder 6 onto the inner peripheral surface of the fork port 51, an annular oil chamber S4 is formed between the outer sub-cylinder 5 and the inner sub-cylinder 6.

Furthermore, an oil seal holder 61 as shown in FIG. An oil groove 62 is formed in the axial direction, and an oil hole 63 is formed to communicate the oil groove 62 and the oil chamber S1, so that the oil chamber S1 is connected to the oil hole 63 of the oil seal holder 61 and the oil groove 62.
An outer sub-cylinder 5 forming a double-structured sub-cylinder 4 from
It communicates with an annular oil chamber S4 between the inner sub-cylinder 6 and the inner sub-cylinder 6.

Furthermore, an oil seal 65 that slides into contact with the outer circumferential surface of the hollow sub-rod 32 is fitted onto the inner circumferential surface of the oil seal holder 61, and the hollow sub-rod 32 is fitted above the oil seal 65.
A rod guide 66 that slides into contact with the outer peripheral surface of the rod is fitted.

The space between the inner circumferential surface of the upper end of the outer sub-cylinder 5 and the outer circumferential surface of the upper end of the inner sub-cylinder 6 is defined as an oil chamber in the cylinder 7 and a temperature compensation chamber 53 for the hydraulic oil in the annular oil chamber S4. An annular free piston 54 is slidably fitted in the temperature compensation chamber 53 so as to be in sliding contact with the inner peripheral surface of the outer sub-cylinder 5, and a spring 55 is inserted between the upper surface of the free piston 54 and the lower surface of the fork pole 51. It is interposed and biased downward to pressurize the hydraulic oil on the lower surface of the free piston. Further, an oil seal 56 is slidably inserted into the outer peripheral surface of the inner sub-cylinder 6, and this oil seal 56 is biased to a closed state by a spring 57 and a spring seat interposed between it and the free piston 54. Furthermore, an oil hole 58 is formed at the upper end of the outer sub-cylinder 5 to communicate between the temperature compensation chamber 53, the inner peripheral surface of the tube 1, and the outer peripheral surface of the outer sub-cylinder 5.

Further, a cap 68 is fitted to the upper end of the fork pole 51 to prevent dust and the like from entering the inner sub-cylinder 6.

The operation of the hydraulic shock absorber configured as above will be explained below.

First, when the hollow piston rod 15 moves upward together with the inner tube 2 during the compression stroke, the piston 26 moves upward within the cylinder 7, and the hydraulic oil in the oil chamber Sl flows into the piston 26.
The compression side pulp 29 is pushed down through the compression side oil passage 27 against the preset force of the valve pressing member 35 to open the oil chamber S.
A part of the hydraulic oil in the oil chamber S1 flows from the oil passage 46 of the piece 31 to the needle 47.
and the bypass oil passage 45 of the piece 25, and flows from the bypass oil passage 45 through the notch 36 into the oil chamber S2.

At this time, at the same time as the hollow piston rod 15 enters into the cylinder 7, the hollow sub-rod 32 exits upward from the cylinder 7 by the amount by which the hollow rod 15 enters, so that an entry volume compensation chamber for the piston rod 15 is no longer required. In addition, each part of this front fork is dimensionally formed to a length such that the sub-rod 32 is accommodated in the outer tube 1 in the compressed state shown in FIG. There is no interference with other members above.

Furthermore, when the hollow piston rod 15 moves downward together with the inner tube 2 during the extension stroke, the piston 26 moves downward within the cylinder 7, and the hydraulic oil in the oil chamber S2 flows into the piston 26.
The expansion side bubble 30 is pushed up through the expansion side oil passage 28 and flows into the oil chamber S1 to generate a damping force, and the oil chamber S2
A part of the hydraulic oil in the piece 25 flows from the notch 36 of the piece 25 through the bypass oil passage 45 into the oil chamber St from between the bypass oil passage 45 and the needle 47 through the oil passage 46 of the piece 31. At this time, at the same time as the hollow piston rod 15 withdraws from the cylinder 7, the hollow sub-rod 32 enters the cylinder 7 by the amount by which the hollow piston rod 15 withdraws, so that a negative pressure state does not occur.

Here, by rotating the adjuster 43, the operating pipe 42 that is fitted in an odd shape therein rotates, and the bushing rod 41 moves up and down. That is.

The operating pipe 42 slides up and down at a contoured fitting portion with an adjuster 43 or a push rod 41 at the upper end. As the bushing rod 41 moves up and down, the spring seat 38 moves up and down via the spring seat support member 37, and the urging force exerted by the spring 39 on the valve pressing member 35 changes, causing the valve pressing member 35 to press the compression side valve 29. Since the pressure (preset force) changes and the pressure required to open the compression side valve 29 changes,
The damping force in the compression stroke can be adjusted.

Further, by rotating the adjuster 49, the operating pipe 48 rotates and the needle 47 moves up and down, changing the opening amount between the needle 47 and the bypass oil passage 45. The flow rate of the hydraulic oil flowing between the oil chamber S1 and the oil chamber S2 through the notch 36 changes, so that the damping force in the compression stroke and the extension stroke can be adjusted.

Furthermore, due to temperature rise, the hydraulic oil in the cylinder 7 expands and its volume increases, or the hollow piston rod 15
When the hydraulic oil in the cylinder outside oil chamber S3 enters the oil chamber S2 from between the oil seal 18 and the outer circumferential surface of the hollow piston rod 15 due to an intruder, the amount of hydraulic oil in the cylinder 7 increases. The increased hydraulic oil passes through the oil groove 62 from the oil hole 63 of the oil seal holder 61, and further flows into the annular oil chamber S4 between the outer sub-cylinder 5 and the inner sub-cylinder 6, gradually moving the free piston 54. push it up.

As the free piston 54 is gradually pushed up, the restoring force of the spring 55 also gradually increases.
The pressure in the oil chamber S4 also increases. When the pressure in the oil chamber S4 exceeds the restoring force of the spring 57, the oil seal 56 separates from the free piston 54 and opens, so the hydraulic oil in the oil chamber S4 flows into the temperature compensation chamber 53, and further from the temperature compensation chamber 53. Furthermore, it returns to the oil chamber S3 through the oil hole 58 and between the outer tube l and the outer sub cylinder 5, so that the cylinder 7
This reduces the internal pressure and prevents significant changes in friction.

5 and 6 are half-sectional views of an upright front fork according to the present invention.

The front fork shown in FIG. 5 has a fork pipe 82 slidably inserted into a bottom case 81 from above.
The upper end of the sub-cylinder 4 is screwed onto the upper end of this fork pipe 82, and the upper end of the cylinder 7 is attached to the lower end of this sub-cylinder 4 so as to face inside the bottom case l, and further inside this cylinder 7. A hollow piston rod 15 whose lower end is screwed onto the bottom case L faces from below, and a piston 26 that slides on the inner peripheral surface of the cylinder 7 is attached to the tip of the hollow piston rod 15. A hollow sub-rod 32 is connected to the upper side of the front fork, so that the hollow sub-rod 32 is housed in the fork pipe 82 when the front fork is in the most compressed state.

Further, in the front fork shown in FIG. 6, a fork pipe 82 is slidably inserted into a bottom case 81 from above, and the lower end of an outer sub-cylinder 5 constituting the sub-cylinder 4 is attached to the inner bottom of the bottom case 81. , screw the lower end of the inner sub-cylinder 6 to the inside of the outer sub-cylinder 5 via the bottom nut 83, attach the lower end of the cylinder 7 to the upper end of the sub-cylinder 4, and insert it into the fork pipe 82. Furthermore, a hollow piston rod 15 whose upper end is screwed onto the fork pipe 82 is faced from above into the cylinder 7, and the cylinder 7 is attached to the tip of the hollow piston rod 15.
A piston 26 that slides on the inner peripheral surface is installed, and a hollow sub-rod 32 is connected to the lower side of the piston 26, so that the hollow sub-rod 32 is housed in the bottom case 81 when the front fork is in the most compressed state.

In the embodiment shown in FIGS. 5 and 6, a damping force 3I is provided at the connecting portion between the hollow piston rod 15 and the hollow sub-rod 32 to adjust the compression-side damping force by changing the preset force of the compression-side valve. A damping force adjustment mechanism is provided to adjust the damping force on the compression side and the expansion side by changing the opening amount between the adjusting mechanism and the needle and the bypass oil passage, and the sub cylinder 4 has a double structure and the inner sleeve chamber of the cylinder 7 is formed. Temperature compensation chamber 5
Since the other specific configurations and functions, such as being used as an oil passage leading to No. 3, are the same as those of the above-mentioned inverted front fork, corresponding parts will be given the same reference numerals and a description thereof will be omitted.

(Effects of the Invention) As explained above, according to the present invention, a double rod damper is interposed in the front fork, and the sub-rod connected to the piston coaxially with the piston rod is housed in the outer tube or fork pipe in the most compressed state. This prevents the outer tube or fork pipe from protruding from the outer tube or fork pipe and interfering with other members, and prevents dust from entering.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of an inverted front fork according to the present invention, FIG. 2 is an enlarged sectional view of essential parts of the front fork,
Fig. 3 is a perspective view of the oil seal holder of the front fork, Fig. 4 is a plan sectional view of the main parts of the front fork, and Figs. 5 and 6 are half sectional views of the upright front fork according to the present invention. It is. In the drawings, l is an outer tube, 2 is an inner tube, 4 is a sub cylinder, 5 is an outer sub cylinder, 6 is an inner sub cylinder, 7 is a cylinder, 15 is a hollow rod, 25
, 31 is a piece, 26 is a piston, 27 is a compression side oil passage,
28 is the extension side oil passage, 29 is the compression side valve, 30 is the extension side valve, 32 is the sub rod, 81 is the bottom case, 82
is a fork pipe. Patent applicant Showa Seisakusho Co., Ltd. Agent
Patent Attorney Part 2 1) Part 1 Patent Attorney
Kuni Ohashi, Patent Attorney, Department
Yama Yu Figure 2

Claims (4)

[Claims] (1) The inner tube is slidably inserted into the outer tube from below, and a cylinder with the upper end attached to the outer tube faces inside this inner tube, and the lower end of the inner tube is attached inside this cylinder. In an inverted motorcycle front fork, the installed piston rod is exposed, and the tip of the piston rod is equipped with a piston that makes sliding contact with the inner circumferential surface of the cylinder, and a sub-rod is connected to the piston on the opposite side of the piston rod. The front fork for a motorcycle is characterized in that the cylinder is attached to the lower end of a sub-cylinder whose upper end is attached to the outer tube, so that the sub-rod is housed in the outer tube in the most compressed state. (2) A fork pipe is slidably inserted into the bottom case from above, the upper end of a cylinder is attached to the upper end of this fork pipe, and the lower end is inserted into the bottom case from below into this cylinder. A front fork for an upright motorcycle is equipped with a piston attached to the tip of the piston rod that slides against the inner peripheral surface of the cylinder, with the attached piston rod facing out, and the piston has a sub-rod on the opposite side of the piston rod. A front fork for a motorcycle, characterized in that the cylinder is attached to the lower end of a sub-cylinder whose upper end is attached to a fork pipe, so that the sub-rod is housed in the fork pipe in the most compressed state. . (3) The inner tube is slidably inserted into the outer tube from below, the cylinder with its lower end attached to the inner tube faces, and the piston rod whose upper end is attached to the outer tube is placed inside the cylinder. In an inverted motorcycle front fork, the piston rod is equipped with a piston that slides on the inner circumferential surface of the cylinder at the tip end thereof, and a sub-rod is connected to the piston on the opposite side of the piston rod, A front fork for a motorcycle, characterized in that it is attached to the upper end of a sub-cylinder whose lower end is attached to an inner tube, so that the sub-rod is housed in the inner tube in the most compressed state. (4) A fork pipe is slidably inserted into the bottom case from above, the lower end of the cylinder is attached to the lower end of the bottom case, and the upper end of the fork pipe is inserted into the cylinder from above. A front fork for an upright motorcycle is equipped with a piston attached to the tip of the piston rod that slides against the inner circumferential surface of the cylinder, with the attached piston rod facing out, and the piston has a sub-rod on the opposite side of the piston rod. A front fork for a motorcycle, characterized in that the cylinder is connected to the upper end of a sub-cylinder whose lower end is attached to a bottom case, so that the sub-rod is housed in the bottom case in the most compressed state. .