JP4454788B2 - Front fork - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a front fork of a motorcycle, and more particularly to a front fork for on-road racing, and can reduce the air reaction force when the vehicle travels at a position where the vehicle is greatly depressed, such as during corner turning. In addition, the present invention relates to a front fork capable of increasing the compression side damping force.
[0002]
[Prior art]
The following performance is required for a front fork for motorcycle on-road racing.
(a) When running straight on a flat road at high speed, increase the road surface vibration absorption with a small air reaction force.
[0003]
(b) When the front fork sinks greatly at a high speed, such as during braking where braking is applied before entering the corner, the subtraction of the front fork should be suppressed with a large air reaction force.
[0004]
(c) When turning at a constant speed with the front fork submerged, such as during cornering after braking, increase the air reaction force and increase the absorption of road surface vibration during cornering. .
[0005]
(d) When the front fork extends from a compressed state, such as during acceleration during cornering, the front fork does not extend to prevent understeer and to improve turning performance.
[0006]
However, in the conventional front fork, the air reaction force rises in a square curve in the second half of the stroke, so it is difficult to reduce the air reaction force. In addition, it is difficult to suppress the extension of the front fork when moving from the compressed state to the extension stroke.
[0007]
Therefore, the present applicant has developed a front fork that satisfies the above required performance and applied for it with Japanese Patent Application No. 11-47133. However, there is room for improvement in the following points.
[0008]
FIG. 5 is a diagram showing the characteristics of the front fork according to the above application. During the compression stroke, a large air reaction force is generated during braking at point a, and the air reaction force is lowered during turning after braking. Increases the absorption of road surface vibration during turning. Further, an air reaction force smaller than that during the compression stroke is generated during the extension stroke, and hysteresis characteristics are generated in the air reaction force. However, as shown by the stroke S centering on the point b, if the posture of steady turning for a long time is maintained, the hysteresis characteristic of the air reaction force is reduced and the effect is lost. Stability is impaired.
[0009]
[Problems to be solved by the invention]
It is an object of the present invention to suppress an increase in air reaction force and improve road surface absorbency when turning while the vehicle is depressed, and to improve the stability of the vehicle while turning by increasing the compression side damping force. It is to provide a front fork that can secure the vehicle and suppress unnecessary movement of the vehicle body.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, the inner tube on the axle side is slidably fitted into the outer tube on the vehicle body side via the upper and lower bushes, and the upper and lower bushes are interposed between the outer tube and the inner tube. An annular oil chamber is formed, and a damper cylinder is erected in the inner tube, and an upper end portion of a piston rod that slides through the piston in the damper cylinder is attached to the outer tube. An oil chamber having an air chamber as an upper portion is provided in a chamber formed in the inner tube, and a first partition member that slidably contacts an inner periphery of the inner tube with the inner periphery of the inner tube via a first piston portion is provided from the outer tube side. An inverted front fork of a motorcycle that is vertically suspended and divides a chamber in the outer tube and the inner tube into an inner chamber and an outer chamber by the first partition member. The second partition member is provided continuously to the lower end of the first partition member, and is slidably contacted with the inner periphery of the inner tube via the second piston portion on the outer periphery of the lower end, and an intermediate chamber is provided outside the second partition member. A suspension spring is disposed between the lower end portion of the second partition member and the inner tube side, and the outer periphery of the piston rod is disposed between the outer periphery of the piston rod and the inner periphery of the second partition member. A cylindrical throttle member that forms an annular throttle channel is provided, and a communication hole that communicates the inner chamber of the second partition member and the outer intermediate chamber is positioned above the throttle member on the outer periphery of the piston rod. The upper communication hole and the lower communication hole are provided in the inner tube with a space in the vertical direction. The upper communication hole is located above the first piston portion. When the lower communication There is obtained so as to form so as to be positioned above said second piston part.
[0011]
According to a second aspect of the present invention, in the first aspect of the invention according to the first aspect, the cylindrical throttle member abuts against an upper end surface of the damper cylinder at the time of the maximum compression, thereby buffering at the time of the maximum compression. The inverted front fork for a motorcycle according to claim 1, which is a stopper member formed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
1 is a partially cutaway front fork according to the present invention, FIG. 2 is an enlarged top view of FIG. 1, FIG. 3 is a schematic cross-sectional view showing an enlarged main part of FIG. 1, and FIG. 5 is a schematic cross-sectional view showing an enlarged compression position, FIG. 5 is a diagram showing air spring characteristics of a front fork in a conventional example, and FIG. 6 is an enlarged cross-sectional view showing a tapered surface where a spring joint and an upper spring collar abut. It is.
[0013]
FIG. 1 is a front view of the front fork according to the present invention with a part thereof broken away, with the left half showing the riding 1G position and the right half showing the compression position at the start of turning.
[0014]
As shown in FIG. 1, in the front fork 100, an inner tube 2 is slidably inserted into an outer tube 1, and the outer tube 1 is coupled to the vehicle body side via an upper bracket (not shown). Is coupled to the axle side via an axle bracket 3. A lower bush 4 slidably contacting the outer periphery of the inner tube 2 is fixed to the inner periphery of the lower opening end of the outer tube 1, and an upper bush 5 slidably contacting the inner periphery of the outer tube 1 is fixed to the upper outer periphery of the inner tube 2. It is fixed. An annular oil chamber S1 is formed between the outer tube 1, the inner tube 2, and the upper and lower bushes 5, 4. The upper bush 5 may be fixed to the inner periphery of the outer tube 1. 6 is an oil seal.
[0015]
A damper cylinder 10 is fixed to the bottom of the axle bracket 3 via a bolt 7, and a bush 13 is provided on the inner periphery of the rod guide 11 at the upper end of the damper cylinder 10 via an O-ring. The piston rod 14 is inserted into the damper cylinder 10, and the piston 12 that slides within the damper cylinder 10 is fixed to the tip of the piston rod 14. An oil chamber A is provided in the damper cylinder 10.
[0016]
An extension side damping force generating device 17 having an extension side valve that generates a damping force when extended and a check valve that opens when compressed is provided at the tip of the piston rod 14. There is provided a compression-side damping force generator 22 including a compression-side valve that generates a compression-side damping force with respect to the hydraulic oil corresponding to the ingress volume, and an extension-side check valve that opens when extended.
[0017]
Reference numeral 23 denotes a compression side damping force adjusting device 27 that adjusts the opening area of the flow path bypassing the pressure side valve by a needle valve provided in the flow paths 24, 25, 26 bypassing the pressure side valve of the pressure side damping force generating device 22. To do. Reference numeral 30 denotes a rebound spring that cushions at the time of maximum extension.
[0018]
The damper cylinder 10, piston 12, piston rod 14, damping force generator and the like described above constitute a damper 32, and this damper 32 is housed in the outer tube 1 and the inner tube 2 in a so-called upright state.
[0019]
Here, as shown in FIG. 2, a cylindrical guide member 33 is screwed to the upper end portion of the piston rod 14 and fixed by a lock nut 34. A concave fork cap 36 having a bottom is liquid-tightly screwed to the inner periphery of the upper end portion of the outer tube 1 via an O-ring, and a lower portion is expanded to the center of the bottom of the fork cap 36 via a step 36a. A female screw hole 36b is provided. On the other hand, a large-diameter male screw portion 33b is provided on the outer periphery of the lower portion of the guide member 33 fixed to the upper end portion of the piston rod 14 via a step portion 33a. Then, the male threaded portion 33b of the cylindrical guide member 33 is screwed into the female threaded hole 36b of the fork cap 36 from below, and a predetermined torque is applied to the stepped portion 33a of the female threaded portion 33b of the guide member 33. Are fastened to the stepped portion 36a of the female screw hole 36b of the fork cap 36, and the upper portions of the guide member 33 and the piston rod 14 are fixed to the outer tube 1 side via the fork cap 36.
[0020]
Three holes 36c are formed in the bottom of the fork cap 36 so as to divide equally in the circumference in the axial direction, and in the three holes 36c, an annular washer portion 37a made of resin and three pins 37b are formed. A pressing member 37 in which is embedded is inserted so as to be movable in the axial direction. In addition, a spring adjuster 40 is rotatably inserted from above into an annular recess formed between the guide member 33 and the fork cap 36, and the spring adjuster 40 is screwed onto the outer periphery of the guide member 33. The annular washer portion 37a of the pressing member 37 is in contact with the lower end of the pressing member 37. The three pins 37b of the pressing member 37 are in contact with the upper surface of the bottom of the cup-shaped spring joint 51. When the spring adjuster 40 is rotated, the pressing member 37 moves up and down to adjust the spring load of a suspension spring 41 to be described later. Make it possible.
[0021]
An adjuster 43 that adjusts the extension side damping force of the piston 12 at the tip of the piston rod 14 is rotatably inserted into the inner periphery of the guide member 33 via the adjustment rod 42.
[0022]
The lower part of the chamber formed outside the damper 32 in the outer tube 1 and the inner tube 2 is filled with hydraulic oil to form an oil chamber B, and the oil chamber B is formed above the oil chamber B via the oil surface L1. A chamber is formed, and this air chamber is divided into an air chamber C1 inside the first partition member 55 and an air chamber C2 outside by a first partition member 55 described later. A communication hole 44 is provided in the lower side wall of the damper cylinder 10 to communicate the oil chamber A in the damper cylinder 10 with the outer oil chamber B.
[0023]
When the front fork 100 is compressed, the piston rod 14 enters the damper cylinder 10, the pressure side check valve is opened, and the hydraulic oil corresponding to the volume of the piston rod 14 that has entered the damper cylinder 10 flows into the compression side damping force generator 22. The pressure side valve is bent and flows out into the lower oil chamber B through the communication hole 44 at the lower part of the damper cylinder 10, and the pressure side valve generates a pressure side damping force. When the piston rod 14 is extended, the piston rod 14 is retracted from the damper cylinder 10 and the expansion side valve is bent to generate an expansion side damping force. Return to the damper cylinder 10 through the side check valve.
[0024]
As shown in FIG. 3, a nut 46 and a holder 47 are fixed to the outer periphery of the piston rod 14 via a stopper ring 45, and the nut 46 and the holder 47 are screwed together. A stopper rubber 48 is fixed by baking.
[0025]
The stopper ring 45, the nut 46, the holder 47, and the stopper rubber 48 constitute a stopper member 50 for a stopper that provides a buffer at the time of maximum compression. The stopper member 50 also serves as a throttle member that forms an annular throttle channel P between the outer periphery of the stopper member 50 and a second partition member 56 described later, as indicated by a broken line in FIG.
[0026]
Further, a tubular portion 51a of a cup-shaped spring joint 51 is fitted and inserted through a lower outer peripheral O-ring 49 on the outer tube 1 side of the fork cap 36, and is formed to project from the lower end surface of the spring joint 51. The upper end surface of the upper spring collar 52 is in contact with the outer periphery of the boss portion 51b via the tapered surfaces 51c and 52c as shown in FIG. A first piston portion 52 d is fitted on the outer periphery of the lower end portion of the upper spring collar 52, and a lower spring collar 53 is connected to the lower end of the first piston portion 52 d, and is provided on the outer periphery of the lower end portion of the lower spring collar 53. Is fitted with a second piston portion 53a. The first piston portion 52d and the second piston portion 53a are in sliding contact with the inner periphery of the inner tube 2, respectively. The cup-shaped spring joint 51, the upper spring collar 52, and the first piston portion 52d constitute a first partition member 55, and the upper chambers in the outer tube 1 and the inner tube 2 are disposed inside the first partition member 55. It is partitioned into a chamber C1 and an outer chamber C2. The O-ring 49 on the outer periphery of the fork cap 36, the tapered surfaces 51c and 52c on which the spring joint 51 and the upper spring collar 52 abut, and the first piston portion 52d hold the inner chamber C1 and the outer chamber C2 in an airtight manner, respectively. . The lower spring collar 53 and the second piston portion 53a constitute a second partition member 56, and an intermediate chamber D defined by the first piston portion 52d and the second piston portion 53a is formed outside the second partition member 56. ing.
[0027]
A suspension spring 41 is disposed between the lower end of the second piston portion 53a and a lower spring receiver 57 supported by a stopper ring on the lower outer periphery of the damper cylinder 10 in a state where a set load is applied. The outer tube 1 and the inner tube 2 are urged in the extending direction via the upper and lower spring collars 52 and 53 and the spring joint 51.
[0028]
An annular throttle channel P is formed on the inner periphery of the second partition member 56 and the outer periphery of the cylindrical throttle member that is the stopper member 50 as shown by a broken line in FIG. The second partition member 56 is formed with a communication hole 61 that communicates the inner chamber C <b> 1 and the outer intermediate chamber D above the throttle member 50.
[0029]
The inner peripheral surface of the inner tube 2 with which the first piston portion 52d is slidably contacted is formed in a taper shape that slightly increases in diameter toward the tip portion. As shown in FIGS. 1 and 3, the oil level L1 of the oil chamber B is set so that the first piston portion 52d is positioned on the oil level L1 when the vehicle 1G is in the riding position 1G. As a result, a slight gap is formed between the outer periphery of the first piston portion 52d and the inner periphery of the inner tube 2 at the position of the ride 1G, and the air chamber C1 inside the first partition wall member 55 is connected to the communication hole 61, It communicates with the outer air chamber C2 through the intermediate chamber D and a slight gap. When the vehicle is compressed from the position of the riding 1G, the slight gap is reduced, and the first piston portion 52d is submerged in the oil chamber B, so that the flow resistance of the hydraulic oil is increased and the inside is increased. Communication between the outer air chambers C1 and C2 is closed.
[0030]
Further, the inner tube 2 is provided with an upper communication hole 62 and a lower communication hole 63 at intervals in the vertical direction. The upper communication hole 62 and the lower communication hole 63 are provided between the outer tube 1 and the inner tube 2. The upper and lower bushes 5 and 4 communicate with an annular oil chamber S1.
[0031]
3, the lower communication hole 63 of the inner tube 2, the annular oil chamber S <b> 1 between the outer tube 1 and the inner tube 2, the upper communication hole 62, the intermediate chamber D, and the communication hole of the lower spring collar 53. Reference numeral 61 denotes a bypass channel Q that bypasses the throttle channel P (indicated by a broken line in FIG. 3) on the outer periphery of the throttle member 50. The interval between the upper and lower communication holes 62 and 63 is set to be smaller than the interval between the first and second piston portions 52d and 53a fitted on the outer circumferences of the upper and lower spring collars 52 and 53, respectively. The lower communication hole 63 is set to be positioned above the second piston portion 53a when positioned above the piston portion 52d. Also, by setting this interval small, the upper and lower communication holes 62 and 63 are simultaneously closed by the first and second piston portions 52d and 53a, respectively, and the annular oil chamber S1 is prevented from being locked. It is out.
[0032]
The front fork 100 of the present invention operates as follows.
(When running straight)
The left half of FIGS. 1 and 3 shows the compression position of the front fork 100 in the riding 1G state (the rider is in a stationary state). When the vehicle travels on a flat straight road surface at high speed, Stroke vertically up and down around the 1G position.
[0033]
During this straight traveling, the inner air chamber C1 and the outer air chamber C2 communicate with each other through a slight gap between the outer periphery of the first piston portion 52d and the tapered surface formed on the inner periphery of the inner tube 2. Therefore, a small air reaction force is generated, and the road surface vibration absorption is improved.
[0034]
Further, in this riding 1G state, the second piston portion 53a on the outer periphery of the lower spring collar 53 is located between the upper communication hole 62 and the lower communication hole 63 of the inner tube 2, so that the lower communication hole 63 of the inner tube 2, Bypass flow path Q (shown by a one-dot chain line in FIG. 3) comprising an annular oil chamber S1 between the inner tube 2 and the outer tube 1, an upper communication hole 62, an intermediate chamber D, and a communication hole 61 of the lower spring collar 53. ) Is open, bypassing an annular throttle channel P (shown by a broken line in FIG. 3) formed between a stopper member 50 as a throttle member and the lower spring collar 53. Therefore, the hydraulic oil in the lower oil chamber B passes through the two flow paths, the throttle flow path P and the bypass flow path Q, and flows into the upper air chamber C1, so that the compression side damping force is generated in the throttle flow path portion. Is small.
[0035]
(When braking)
FIG. 4 shows a state during braking of the vehicle. When the vehicle is braked and decelerated just before approaching the corner, the front fork 100 on the front wheel side sinks greatly. In this state, as shown in the left part of FIG. 4, the first piston part 52 d provided on the outer periphery of the lower part of the first partition wall member 55 moves downward, and the outer periphery of the first piston part 52 d and the inner periphery of the inner tube 2. Since the first piston portion 52d enters the oil chamber B, the flow resistance of the hydraulic oil increases, and the communication through the clearance on the outer periphery of the first piston portion 52d is closed. . Further, since the upper communication hole 62 of the inner tube 2 is still located below the first piston portion 52d, the air chambers C1 and C2 on both sides of the first partition member 55 are not in communication. Therefore, the oil level L1 of only the air chamber C1 inside the first partition member 55 rises, and the air chamber C1 inside the first partition member 55 is greatly compressed to generate a large air reaction force. As a result, the front wheel side fork 100 is prevented from sinking.
[0036]
Further, at the time of braking, the lower communication hole 63 of the inner tube 2 serving as an inlet of the bypass flow path Q that bypasses the throttle flow path P moves above the second piston portion 53a, so that the bypass flow path Q is closed. Thus, the hydraulic oil flows upward only through the throttle channel P (indicated by a broken line) on the outer periphery of the throttle member 50. As a result, the compression side damping force also increases, and the sinking of the front fork 100 is effectively suppressed.
[0037]
(Turning state)
1 and 3 show the turning state of the vehicle after braking. In this turning state, the vehicle travels in a state where both the front wheel side and the rear wheel side are greatly depressed by centrifugal force.
[0038]
In this turning state, the first piston portion 52 d provided on the outer periphery of the first partition member 55 moves below the upper communication hole 62 of the inner tube 2, and the upper communication hole 62 is an air outside the first partition member 55. Open to chamber C2. As a result, the air chamber C1 inside the first partition member 55 is connected to the communication hole 61 of the lower spring collar 53, the lower communication hole 63 of the inner tube 2, and the inner tube 2 and the outer tube 1 via the oil chamber B. The annular air chamber S1 and the upper communication hole 62 communicate with the outer air chamber C2. Then, until the pressure in the inner air chamber C1 is balanced with the pressure in the outer air chamber C2, the hydraulic oil in the inner air chamber C1 flows into the outer air chamber C2, and the air reaction force decreases. As a result, it is possible to suppress an increase in the air reaction force at the compression position that is greatly depressed, and it is possible to increase the absorbability of the road surface vibration during the turning state.
[0039]
Even in this turning state, the lower communication hole 63 of the inner tube 2 is located above the second piston portion 53a and the bypass flow path Q is closed, so that the hydraulic oil flow path in the lower oil chamber is the throttle flow path P. (Indicated by a broken line in the right half of FIG. 3). Therefore, in this turning state, when vibration is transmitted from the road surface side through the road surface gap, since the hydraulic oil flow path is only the throttle flow path P, the compression side damping force can be increased. A large damping force is generated against vibrations from the vehicle, preventing the vehicle from moving too much against disturbance and losing stability.
[0040]
In the present embodiment, the embodiment in which the oil chamber A in the damper cylinder 10 and the oil chamber B outside the damper cylinder 10 communicate with each other has been described, but the present invention can also be applied to those in which these do not communicate. .
[0041]
【The invention's effect】
As described above, according to the present invention, the front fork 100 is greatly compressed during corner turning after braking, and the first piston portion 52d on the outer periphery of the first partition wall member 55 moves downward, and the upper portion of the inner tube 2 is moved. When the communication hole 62 moves upward from the first piston portion 52d on the outer periphery of the first partition member 55, the air chambers on both sides of the first partition member 55 are connected to the communication hole 61 of the second partition member 56 and the lower communication hole of the inner tube 2. 63, it communicates via the annular oil chamber S1 between the outer tube 1 and the inner tube 2 and the upper communication hole 62 of the inner tube portion. As a result, the volume of the air chamber increases and the air reaction force decreases. At this time, the lower communication hole 63 of the inner tube 2 is formed so as to be positioned above the second piston portion 53a on the outer periphery of the lower spring collar 53, so that the lower communication hole 63 of the inner tube 2, the outer tube 1 and The bypass flow path Q including the annular oil chamber S <b> 1 between the inner tubes 2, the upper communication hole 62, and the communication hole 61 of the lower spring collar 53 is closed. As a result, the hydraulic oil flow path becomes only the throttle flow path P between the stopper member 50 as the cylindrical throttle member and the second partition member 56, and the compression side damping force is increased. Accordingly, when the vehicle travels in a depressed state as in a steady turn, even if the air reaction force of the front fork 100 decreases, the compression side damping force increases, so that the shock absorption of road surface vibration during the turn is increased. As well as machine behavior stability.
[Brief description of the drawings]
FIG. 1 is a front view of a front fork according to the present invention, partially broken away.
FIG. 2 is an enlarged top view of FIG.
3 is a schematic cross-sectional view showing an enlarged main part of FIG.
FIG. 4 is an enlarged schematic sectional view showing a compression position during braking.
FIG. 5 is a diagram showing air spring characteristics of a front fork in a conventional example.
FIG. 6 is an enlarged cross-sectional view showing a tapered surface on which the spring joint and the upper spring collar abut.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 4 Lower bush 5 Upper bush 41 Suspension spring 50 Diaphragm member 52d 1st piston part 53a 2nd piston part 55 1st partition member 56 2nd partition member 61 Communication hole 62 Upper communication hole 63 Lower communication hole 100 Front fork S1 Annular oil chamber B Oil chamber C1 Inner chamber C2 Outer chamber D Intermediate chamber

Claims (2)

The inner tube on the axle side is slidably fitted into the outer tube on the vehicle body side via the upper and lower bushes,
Forming an annular oil chamber defined by the upper and lower bushes between the outer tube and the inner tube;
A damper cylinder is erected in the inner tube, and the upper end of the piston rod that slides through the piston in the damper cylinder is attached to the outer tube.
An oil chamber having an upper air chamber is provided in a chamber formed in the outer tube and the inner tube,
A first partition member that slidably contacts the inner periphery of the inner tube via the first piston portion on the outer periphery of the end portion is suspended from the outer tube side, and the chamber in the outer tube and the inner tube is formed by the first partition member. In an inverted front fork of a motorcycle that divides
A second partition member is provided continuously to the lower end of the first partition member and slidably contacts the inner periphery of the inner tube via the second piston portion on the outer periphery of the lower end, and an intermediate chamber is defined outside the second partition member. A suspension spring is disposed between the lower end of the second partition member and the inner tube side,
Provided on the outer periphery of the piston rod is a cylindrical throttle member that forms an annular throttle channel between the outer periphery of the piston rod and the inner periphery of the second partition member;
A communication hole for communicating the inner chamber of the second partition member and the intermediate chamber on the outer side is provided so as to be positioned above the throttle member on the outer periphery of the piston rod, and the upper portion is spaced apart in the vertical direction from the inner tube. A communication hole and a lower communication hole are provided,
The positions of the upper communication hole and the lower communication hole are formed such that when the upper communication hole is located above the first piston part, the lower communication hole is located above the second piston part. An inverted front fork for motorcycles. 2. The inverted front fork for a motorcycle according to claim 1, wherein the cylindrical throttle member is a stopper member that abuts against an upper end surface of the damper cylinder at the time of the maximum compression and cushions at the time of the maximum compression.

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