JP4162178B2 - Front fork - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a front fork that serves as both a shock absorber and a fork, which are interposed between a vehicle body and an axle of a motorcycle or a bicycle to attenuate vibrations from a road surface.
[0002]
[Prior art]
In general, a front fork interposed between a motorcycle body and an axle is provided with a cushion member in order to reduce a sudden impact in the vicinity of the maximum compression.
[0003]
As this type of front fork, for example, one disclosed in JP-A-10-103399 has been developed.
[0004]
In this front fork, a wheel side inner tube is slidably inserted into a vehicle body side outer tube, a damper cylinder is erected in the center of the inner tube, and a piston rod is inserted into the damper cylinder movably via a piston. The end is joined to the upper end cap of the outer tube. Further, a suspension spring is interposed between the upper end of the damper cylinder and the cap of the outer tube, a cushion member is provided on the outer periphery of the upper part of the piston rod, the inner periphery of the suspension spring is guided on the outer periphery of the piston rod, and the cushion member and Opposing push rods are provided to be movable up and down.
[0005]
According to the front fork described above, in the vicinity of the most compressed state, the damper cylinder contacts the lower portion of the push rod and raises it according to the compression stroke, whereby the upper end of the push rod contacts the cushion member and the cushion The members are gradually compressed to prevent sudden bottoming and sudden impacts.
[0006]
[Problems to be solved by the invention]
In the front fork of the type disclosed in the above publication, the cushion member is provided directly on the reservoir in the outer tube because the cushion member is provided on the upper part of the piston rod. Contact with oil.
[0007]
On the other hand, the cushion member is preferably formed of a material having an appropriate repulsive force and having a high impact absorption performance, such as urethane foam.
[0008]
However, as described above, when a cushion member formed of a material such as urethane foam is soaked in hydraulic oil, the cushion member may be broken in use during use, and the cushion function may be impaired.
[0009]
For this reason, in the past, it has been necessary to select a highly oil-resistant material that does not become sluggish even when it comes in contact with hydraulic oil, resulting in increased material costs and insufficient cushion function. Yes.
[0010]
Accordingly, an object of the present invention is to use a cushion member formed of a material that prevents the cushion member from coming into contact with the hydraulic oil or becomes immersed in the hydraulic oil, and has a moderate rebound force and high impact absorption performance. Is to provide a front fork.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, one means of the present invention is as follows: 1. The wheel side inner tube is slidably inserted into the vehicle body side outer tube, and the damper cylinder is erected at the center of the inner tube. A piston rod movably inserted into the damper cylinder via a piston is linked to the outer tube, a suspension spring is interposed between the damper cylinder and the outer tube, a reservoir is provided in the vehicle body side outer tube, and the piston rod the upper outer periphery at a front fork is provided with the push rod facing the cushion member and the cushion member, a guide pipe for guiding the inner circumference of the suspension spring in the upper outer peripheral side of the piston rod is provided for, and the guide pipe , A pusher that is movably inserted into the guide pipe via a seal. An air chamber isolated from the hydraulic fluid of the reservoir is provided in the guide pipe with the head of the rod, and an elastic cushion member that is compressed by the push-up operation of the head is inserted into the air chamber. is there.
[0012]
In this case, the guide pipe has a base part screwed on the upper part of the piston rod, a pipe body that hangs downward from the base part and guides the inner periphery of the suspension spring, and a guide part provided inwardly at the lower end of the pipe body. It is preferable that a tapered surface or a curved surface for preventing interference of the suspension spring is formed on the outer periphery of the lower end of the guide portion .
[0013]
Similarly, the other means is that the wheel side inner tube is slidably inserted into the vehicle body side outer tube, the damper cylinder is erected in the center of the inner tube, and the piston is movably inserted into the damper cylinder via the piston. The rod is linked to the outer tube, a suspension spring is interposed between the damper cylinder and the outer tube, a reservoir is provided in the vehicle body side outer tube, and the cushion member and the push member facing the cushion member are arranged on the upper outer periphery of the piston rod. In the front fork provided with a rod, a guide pipe is provided at the upper part of the outer tube, and an air chamber isolated from the hydraulic fluid of the reservoir is provided in the guide pipe via a free piston, and is expanded and contracted in the air chamber. A flexible cushion member is installed facing the free piston. , Further with guiding the inner circumference of the suspension spring to the upper outer periphery of the piston rod, provided with a push rod to compress the cushion member via the free piston by operating the push-up upper end movably to face the free piston It is characterized by.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
1 and 2 show an embodiment of the present invention.
[0016]
The basic structure of the front fork F shown in FIGS. 1 and 2 is the same as that of the conventional front fork. The wheel side inner tube 2 is slidably inserted into the vehicle body side outer tube 1, and the damper cylinder DP is placed in the center of the inner tube 2. The piston rod 3 movably inserted into the damper cylinder DP through the piston is connected to and linked with the upper end cap 4 of the outer tube 1, and the upper end of the damper cylinder DP and the upper end cap 4 of the outer tube 1 are A suspension spring 5 is interposed between the piston rod 3 and a cushion member 6 and a push rod 7 facing the cushion member 6 is provided on the upper outer peripheral side of the piston rod 3.
[0017]
In the present invention, a guide pipe 8 for guiding the inner periphery of the suspension spring 5 is further provided on the upper outer peripheral side of the piston rod 3, and the cushion member 6 and the upper part of the push rod 7 are inserted into the guide pipe 8 in series. Yes.
[0018]
The guide pipe 8 includes a base portion 8a screwed to the upper portion of the piston rod 3, a pipe body 8b suspended downward from the base portion 8a, and a guide portion 8c provided inwardly at the lower end of the pipe body 8b. The guide pipe 8 guides the inner periphery of the suspension spring 5 to smoothly extend and retract the suspension spring 5 and prevent buckling.
[0019]
The lower periphery of the guide portion 8c tapered surface or a curved surface T is formed, the lower end of the guide pipe 8 is prevented from interfering with the suspension spring 5.
[0020]
The push rod 7 is composed of a pipe-shaped main body 7a and a piston type head 7b integrally provided at the upper end of the main body 7a. The push rod 7 is slidably inserted into the guide pipe 8 through the head 7b. Yes.
[0021]
The guide portion 8c of the guide pipe 8 guides the push rod 7 in the vertical direction, and a seal S1 is provided on the inner periphery thereof. Similarly, a seal S2 is provided on the inner periphery of the head 7b of the push rod 7. When the guide portion 8c is in sliding contact with the main body 7a of the push rod 7 and the head 7b of the push rod 7 is in sliding contact with the inner periphery of the guide pipe 8, the head 7b of the push rod 7 is engaged with the guide portion 8c when lowered. The slip-off is prevented.
[0022]
In the guide pipe 8, an air chamber 9 is provided that is isolated from the hydraulic oil in the reservoir R in the outer tube 1 by the guide pipe 8 and the head 7b of the push rod 7, and the air chamber 9 is sealed by the seals S1 and S2. Has been.
[0023]
A cushion member 6 is inserted into the air chamber 9 so as to be extendable and contractable. The cushion member 6 is composed of, for example, a single body made of a plurality of urethane foams having different inner diameters. The cushion member 6 may be composed of a single member, or a plurality of single bodies of different materials may be assembled in series. As the material of the cushion member 6, it is preferable to use a material made of, for example, urethane foam, rubber or the like, which has a hysteresis characteristic in the repulsive force and has a high impact absorption performance.
[0024]
The guide pipe 8 guides the outer periphery of the cushion member 6 and prevents the cushion member 6 from buckling. However, buckling may be prevented by the piston rod 3 by sliding the inner periphery of the cushion member 6 against the outer periphery of the piston rod 3.
[0025]
Next, the operation during compression will be described.
[0026]
As shown in FIG. 2, when the outer tube 1 is compressed and stroked to the vicinity of the maximum compression, the upper end head 10 of the damper cylinder DP contacts the lower end of the push rod 7, and when the compression stroke is further performed, the damper rod DP pushes the push rod. 7a is pushed upward. Therefore compressing the cushion member 6 pushes up the head 7b of the push rod 7 is a cushion member 6, exerts a cushioning effect to absorb the abrupt bottoming or sudden impact during compression by compression of the cushioning member 6 The riding comfort of motorcycles and the like during compression is improved.
[0027]
Since the cushion member 6 is isolated from the hydraulic oil, adverse effects caused by the hydraulic oil, for example, the material is prevented from being sagged or raged.
[0028]
FIG. 3 relates to the embodiment of the present invention, which is a slight modification of the guide pipe 8 and the push rod 7 of FIG. 1, and the other structures, operations, and effects are the same as those of the front fork F of FIG. It is.
[0029]
That is, the guide pipe 8 includes a base portion 8a and a pipe body 8d that is integrally suspended from the base portion 8a, and a taper is formed at the lower end of the pipe body 8d. On the other hand, the push rod 7 is composed of a pipe-like thick main body 7c, and the upper portion of the pipe body 7c is inserted into the guide pipe through the seal S3 so as to be slidable up and down.
[0030]
In the guide pipe 8, an air chamber 9 separated from the hydraulic oil is defined by the guide pipe 8, the head portion of the push rod 7 and the seal S 3, and the cushion member 6 is inserted in the air chamber 9 in an extendable manner. is doing.
[0031]
A large-diameter portion 12 that forms an annular gap with the outer periphery of the piston rod 3 is formed along the axial direction on the lower inner side of the pipe body 7c of the push rod 7, and a snap ring or the like is formed on the outer periphery of the piston rod 3. A stopper 13 is provided, and the push rod 7 moves up and down without interfering with the stopper 13 by the large diameter portion 12 and the upper end wall of the large diameter portion 12 abuts against the stopper 13 when descending and the push rod 7 is pulled out downward. Is preventing. Further, since the downward outer periphery of the push rod 7 to a larger diameter as shown, it is possible to prevent the buckling of the suspension spring 5 come in can guide the suspension spring 5 in the large diameter portion .
[0032]
During the compression operation, as in the case of FIG. 1, the push rod 7 is urged upward by the damper cylinder DP, and the cushion member 6 is compressed to apply the cushion.
[0033]
In the front fork according to the embodiment of FIGS. 1 to 3, the guide pipe 8 and the cushion member 6 are disposed inside the suspension spring 5, and the suspension spring 5 is disposed at the upper end of the damper cylinder and the upper end cap 4 of the outer tube 1. Therefore, the suspension spring 5 can make the suspension spring 5 longer than the type disclosed in the above-mentioned conventional publication, and can take a longer expansion / contraction stroke.
[0034]
FIG. 4 relates to another embodiment of the present invention, in which a guide pipe 8 and a cushion member 6 are arranged in series above the suspension spring 5 as compared with the embodiment of FIGS. is there.
[0035]
As with the conventional front fork, the front fork F also has a wheel side inner tube 2 slidably inserted into the vehicle body side outer tube 1, and a damper cylinder DP is erected in the center of the inner tube 2. The piston rod 3 movably inserted through the piston is connected to and linked with the cap 4 of the outer tube 1, and a suspension spring 5 is interposed between the upper end of the damper cylinder DP and the upper end cap 4 of the outer tube 1. Is.
[0036]
Further, a cushion member 6 and a push rod 7 facing the cushion member 6 are provided on the upper outer peripheral side of the piston rod 3. In contrast to the basic structure of the front fork, in the present invention, a guide pipe 8 coupled to the cap 4 is provided on the upper portion of the outer tube 1 so as to face downward. An isolated air chamber 9 is provided, and a retractable cushion member 6 is provided in the air chamber 9 so as to face the piston 13. Furthermore, a push rod 7 for guiding the inner periphery of the suspension spring 5 is provided on the outer periphery of the upper portion of the piston rod 3 so as to be opposed to the free piston 13.
[0037]
The guide pipe 8 includes a pipe body 8 e that is suspended downward. The pipe body 8 e is supported by the lower end of the cap 4 through a support piece 14, and the lower end carries the upper end of the suspension spring 5.
[0038]
The free piston 13 is provided with a seal on the inner and outer peripheries to prevent hydraulic oil from entering the air chamber 9.
[0039]
The push rod 7 is composed of a pipe-like main body 7d that guides the inner periphery of the suspension spring 5, and large-diameter portions 15 and 16 are formed on the upper inner side and the lower inner side.
[0040]
A stopper 13 made of a snap ring is provided on the outer periphery of the piston rod 3, and this stopper 13 restricts the downward movement of the push rod 7. The cushion member 6 is integrally formed of urethane foam, rubber or the like, and is formed so as to be easily compressed by forming a plurality of annular grooves on the outer periphery.
[0041]
In the above front fork, the upper end of the damper cylinder DP in the vicinity at highest compression raised to press it in contact with the push rod 7, then, by compressing the cushion member 6 the upper end of the push rod 7 through a piston 13 It is what makes the cushion work.
[0042]
【The invention's effect】
The present invention has the following effects.
[0043]
(1) According to the inventions of the first, second, and third aspects, since the cushion member is provided in the air chamber isolated from the hydraulic fluid of the reservoir , the cushion member is damaged by the hydraulic fluid and is damaged. Is prevented. As a result, regardless of the resistance oil, the repulsive force has a hysteresis characteristic, a material with high shock absorption, for example, be used those urethane foam, formed of rubber or the like, thereby improving the cushioning effect. Further, it is possible to use a cushion member made of an inexpensive material weak in oil resistance.
[0044]
(2) According to the invention of claim 1, since the guide pipe and the cushion member are provided inside the suspension spring, the entire length of the suspension spring can be increased without being interfered by the guide pipe and the cushion member, and the expansion / contraction stroke Can be taken longer.
( 3) According to the invention of claim 2, since the inner periphery of the suspension spring can be guided by the pipe body of the guide pipe, the suspension spring can be smoothly expanded and contracted, and buckling can be prevented.
Further, it is possible to prevent the lower end of the guide pipe from interfering with the suspension spring by the tapered surface or the curved surface provided on the outer periphery of the lower end of the guide portion.
[Brief description of the drawings]
FIG. 1 is a partially cut longitudinal front view of a front fork according to an embodiment of the present invention.
FIG. 2 is a longitudinal front view showing a compressed state of the front fork of FIG. 1;
FIG. 3 is a longitudinal front view of a front fork according to another embodiment of the present invention.
FIG. 4 is a longitudinal front view of a front fork according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Car body side outer tube 2 Wheel side inner tube 3 Piston rod 5 Suspension spring 6 Cushion member 7 Push rod 7b Head 8 Guide pipe
8a base
8b pipe body
8c guide part 9 Air chamber 13 Piston S1, S2 Seal DP Damper cylinder
T curved surface

Claims (3)

A wheel side inner tube is slidably inserted into the vehicle body side outer tube, a damper cylinder is erected in the center of the inner tube, and a piston rod movably inserted into the damper cylinder via a piston is interlocked with the outer tube. A suspension spring is interposed between the damper cylinder and the outer tube, a reservoir is provided in the vehicle body side outer tube, and a cushion member and a push rod facing the cushion member are provided on the outer periphery of the upper part of the piston rod. In the fork, a guide pipe that guides the inner periphery of the suspension spring is provided on the upper outer peripheral side of the piston rod, and the guide pipe and a push rod head that is movably inserted into the guide pipe via a seal. In the guide pipe, the reservoir is separated from the hydraulic fluid. Front fork to the air chamber provided with, characterized in that the insertion of the retractable cushion member which is compressed by the push-up operation of the head in the air chamber. The guide pipe is composed of a base screwed to the top of the piston rod, a pipe body that hangs downward from the base to guide the inner periphery of the suspension spring, and a guide section that is provided inwardly at the lower end of the pipe body. The front fork according to claim 1, wherein a tapered surface or a curved surface for preventing interference of the suspension spring is formed on the outer periphery of the lower end of the guide portion . A wheel side inner tube is slidably inserted into the vehicle body side outer tube, a damper cylinder is erected in the center of the inner tube, and a piston rod movably inserted into the damper cylinder via a piston is interlocked with the outer tube. A suspension spring is interposed between the damper cylinder and the outer tube, a reservoir is provided in the vehicle body side outer tube, and a cushion member and a push rod facing the cushion member are provided on the outer periphery of the upper part of the piston rod. In the fork, a guide pipe is provided at the upper part of the outer tube, and an air chamber isolated from the hydraulic oil of the reservoir is provided in the guide pipe via a free piston, and a retractable cushion member is provided in the air chamber. The piston lock While guiding the inner circumference of the suspension spring to the upper periphery, characterized in that the push rod to compress the cushion member via the free piston by operating the push-up upper end provided movably to face the free piston Front fork.

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