JP3932251B2 - 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 that are interposed between a vehicle body and wheels of a vehicle such as a motorcycle and attenuates vibrations from a road surface.
[0002]
[Prior art]
As a conventional front fork, for example, the one shown in Japanese Utility Model Laid-Open No. 57-189993 is known. As shown in FIG. 3, this front fork has an inner tube 33 slidable in an outer tube 31. The seat pipe 34 is erected at the lower end of the outer tube 31, the valve 32 a provided on the inner tube 33 is slidably contacted with the outer periphery of the seat pipe 34, and the lower oil chamber 35 of the outer tube 31 is in contact with the seat pipe 34. It has what has the through-holes 37 and 43 which connect the oil chamber 36 of the seat pipe 34. As shown in FIG.
[0003]
Further, in the front fork, an oil hole 41 is provided on the bottom of the outer tube 31 to cooperate with an oil lock collar 32b provided on the inner periphery below the inner tube 33 to perform an oil lock function.
[0004]
In addition, a bolt 38 incorporating a valve device V having a proportional damping force characteristic in a lower part in the seat pipe 34 is detachably screwed, and is housed in a valve case 45 coupled to the tip of the bolt 38. The valve element 39 urged by the spring 42 is in contact with the valve seat 40 formed at the end of the bolt 38 so as to be freely opened and closed.
[0005]
Therefore, according to such a front fork structure, a jig is inserted into the lower portion of the bolt 38, the screw of the bolt 38 is loosened, and the bolt 38 is removed from the seat pipe 34 together with the valve device V. 39 or the like can be taken out of the outer tube 1 and repaired or exchanged.
[0006]
[Problems to be solved by the invention]
However, in such a conventional front fork, the bolt 38 screwed into the seat pipe 34 is removed downward from the bottom of the outer tube 31 when changing the spring 42 or the like in order to change the damping characteristic. Therefore, the lower end of the seat pipe 36 is in an open state, and therefore the internal hydraulic oil is lost.
[0007]
Further, since various operations for loosening the bolt are performed from the lower side of the vehicle body, there is a problem that it is extremely difficult to replace the parts such as the spring 42 when the bolt is attached to the vehicle body.
[0008]
Further, the spring 42 that urges the valve body 39 of the valve device V prevents the flow of hydraulic oil flowing through the oil chamber 36 and the through hole 37, or slows the circulation of the hydraulic oil into the reservoir 44 during assembly. There was a problem.
[0009]
This invention solves such a conventional problem, and can easily replace components such as a spring from above the vehicle body side tube, and can prevent hydraulic oil from coming off and loosening of components when replacing components, The purpose of the present invention is to obtain a front fork capable of smoothing the flow of hydraulic oil in the expansion stroke.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the means of the present invention includes a vehicle body side tube and a wheel side tube that are slidably fitted, a seat pipe is erected in the center of the wheel side tube, and an upper outer periphery of the seat pipe is provided. An upper oil chamber and a lower oil chamber are formed in sliding contact with the inner periphery of the vehicle body side tube and separated by a check valve provided at the lower part of the vehicle body side tube outside the seat pipe, and an oil chamber is provided in the seat pipe. The oil chamber communicates with the lower oil chamber via a lower port formed in the seat pipe, and further includes a suspension spring for biasing the vehicle body side tube in the extending direction above the seat pipe. The suspension spring receiving part formed on the upper part of the valve case is held inside the lower end, and the lower part of the valve case is inserted into the inner periphery of the upper part of the seat pipe. Is characterized in that a port for communicating the oil chamber with an oil chamber on the reservoir side is formed, and a pressure side relief valve and a check valve are arranged at the outlet end of the port.
[0011]
As a result, the valve case and the suspension spring can be easily detached from the upper end of the vehicle body side tube with the valve case and the suspension spring as one unit, so that the relief valve in the valve case can be removed. Parts such as check valves can be replaced quickly and reliably without draining the hydraulic oil in the seat pipe.
[0012]
In the above means, a guide rod is erected at the center of the valve case, and the pressure side relief valve is inserted into the lower outer periphery of the guide rod so as to be movable up and down, and a spring is provided between the pressure side relief valve and the spring seat above the guide rod. It is preferable to intervene.
[0013]
Similarly, in the above-described means, a spring seat may be screwed onto the guide rod, a loosening prevention nut may be screwed onto the spring seat, and the initial spring load of the spring may be adjusted according to the spring seat position. In this case, the damping force characteristic of the compression side relief valve can be arbitrarily adjusted.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a main portion of an upright front fork according to the present invention, and is shown in an outer tube as a wheel side tube 1. An inner tube which is the vehicle body side tube 2 is fitted so as to be slidable in the axial direction.
[0015]
A seat pipe 3 is erected from the bottom of the wheel side tube 1 at the center thereof, and the base of the seat pipe 3 is held by a bolt 4 screwed into the bottom of the wheel side tube 1. An oil hole 5 is attached so as to cover the outer periphery of the lower end of the seat pipe 3.
[0016]
An oil chamber 6 is provided in the seat pipe 3, and an upper oil chamber 27 and a lower oil chamber 22 separated by a check valve 25 provided at the lower portion of the vehicle body side tube 2 are provided outside the seat pipe 3. Yes.
[0017]
Further, an upper port 7 and lower ports 8 a and 8 b are formed in the upper and lower portions of the seat pipe 3 to communicate the upper oil chamber 27 and the lower oil chamber 22 with the oil chamber 6 in the seat pipe 3, respectively.
[0018]
A valve mounting portion 3a having a U-shaped cross section is formed in a ring shape at the upper end portion of the seat pipe 3 by drawing or the like as shown in FIG. 2, and a check valve 9 is provided on the vehicle body side on the outer periphery of the valve mounting portion 3a. The upper oil chamber 27 and a reservoir, which will be described later, are provided to open and close in sliding contact with the inner periphery of the cylinder 1.
[0019]
In the lower part of the vehicle body side tube 2, a lower end of a cylindrical member 21 that engages with the oil hole 5 in the most compression stroke of the front fork and exerts an oil locking action is fixed, and the cylindrical member 21 and the seat pipe 3 are fixed. The oil passage 23 communicating with the lower oil chamber 22 below the cylindrical member 21 and the check valve 25 urged by the spring 24 in the closing direction at all times are provided to be openable and closable. It has been.
[0020]
An oil passage hole 26 is formed in the upper part of the tubular member 21, and the oil passage hole 26 communicates with the upper oil chamber 27 formed between the valve mounting portion 3 a and the tubular member 21.
[0021]
A spring 28 is provided below the valve mounting portion 3a so as to prevent the cylindrical member 21 from abruptly colliding with the valve mounting portion 3a and to apply a cushion.
[0022]
Further, the lower portion of the cylindrical member 21 is a trumpet-shaped taper portion that can be smoothly fitted into the oil hole 5.
[0023]
Further, the lower outer periphery of the valve case 10 is fitted to the inner periphery of the valve mounting portion 3a, and a flange portion 10a protruding from the outer periphery of the valve case 10 is in contact with the upper end surface of the valve mounting portion 3a.
[0024]
Further, a cylindrical suspension spring receiving portion 10b is extended above the flange portion 10a, and the inner periphery of the lower end of the suspension spring 11 has a predetermined engagement holding force on the outer periphery of the suspension spring receiving portion 10b. For this reason, a reduced diameter portion 10c that increases the engagement holding force is formed on the outer periphery thereof.
[0025]
The upper end of the suspension spring 11 is supported by a cap 12 at the upper end of the vehicle body side tube 2 directly or via a spring guide (not shown). The cap 12 is detachably attached to the upper end of the vehicle body side tube 2 by screwing or the like. Is attached.
[0026]
In addition, a guide rod 13 protrudes integrally at the center of the valve case 10, and a plurality of ports 14 are provided in the valve case 10 around the guide rod 13.
[0027]
The valve case 10 separates an oil chamber 6 in the seat pipe 3 and a reservoir-side oil chamber 15 in the vehicle body side tube 1, and the two oil chambers 6 and 15 communicate with each other through the port. .
[0028]
A check valve 16 is provided in the valve case 10 so as to be vertically movable at a position facing the port 14.
[0029]
On the other hand, a step portion is formed in the vicinity of the position of the outer periphery of the guide rod 13 facing the check valve 16, and a pressure side relief valve 17 comprising a leaf valve is placed on the step portion so as to be inserted.
[0030]
Further, a spring seat 19 carrying a coiled spring 18 is fitted into the guide rod 13 into which the compression side relief valve 17 is inserted, and a nut 20 a and a locking nut 20 b are provided on the upper portion of the guide rod 13. It is screwed in and supported from above so as not to come out of the spring seat 19.
[0031]
Therefore, the initial spring load of the spring 18 can be adjusted according to the screwing amount of the nut 20a, and the damping force characteristic of the pressure side relief valve 17 can be set to a predetermined value. At this time, the pressure side relief valve 17 is set to the check valve 16 Are opposed to each other with a predetermined interval.
[0032]
Next, the operation of the front fork will be described. First, in the extension stroke of the front fork, the wheel side tube 1 is lowered with respect to the vehicle body side tube 2.
[0033]
For this reason, the seat pipe 3 attached to the wheel side tube 1 is also lowered, and the working oil in the upper oil chamber 27 flows out from the upper port 7 of the seat pipe 3 into the oil chamber 6. Generates extensional damping force.
[0034]
At this time, the check valves 9 and 25 are closed by the internal pressure of the upper oil chamber 27 and prevent the oil from flowing into the oil chamber 15 and the lower oil chamber 22, respectively.
[0035]
Further, hydraulic oil corresponding to the withdrawal volume of the vehicle body side tube 2 is supplied from the oil chamber 6 to the lower oil chamber 22 via the lower ports 8a and 8b.
[0036]
At this time, the check valve 16 is pushed open from the reservoir side, and the oil flows smoothly into the oil chamber 6.
[0037]
On the other hand, in the pressure stroke of the front fork, the wheel side tube 1 rises with respect to the vehicle body side tube 2, so that the seat pipe 3 also rises, and the hydraulic oil in the lower oil chamber 22 partially pushes the check valve 25. Opened and flows out into the upper oil chamber 27, and hydraulic oil corresponding to the intrusion volume of the vehicle body side tube 2 flows out into the oil chamber 6 in the seat pipe 3 via the lower ports 8a and 8b, and further operates in the oil chamber 6. The oil flows out into the reservoir-side oil chamber 15 through a gap between the pressure-side relief valve 17 and the check valve 16.
[0038]
At this time, in the low speed region of the lowering speed of the vehicle body side tube 2, a damping force is generated by the flow resistance due to the gap, and when the speed becomes a middle / high speed region, the internal pressure of the lower oil chamber 22 increases, so the pressure side relief valve 17 is pushed up against the spring 18, and a damping force corresponding to the opening amount of the gap is generated in the middle and high speed range.
[0039]
Further, at the time of the above, the check valve 9 is opened in the upper oil chamber 27 and the hydraulic oil is supplied from the oil chamber 15 on the reservoir side.
[0040]
In the front fork operating in this way, there are cases where it is desired to replace parts such as the check valve 16, the pressure side relief valve 17, and the spring 18 and to adjust the deflection of the pressure side relief valve 17.
[0041]
In this case, in a state where the wheel side tube 1 is attached to the wheel side, the cap 12 attached to the upper end of the vehicle body side tube 2 is removed, and a jig is attached to the upper end portion of the suspension spring 11 together with the spring guide (not shown). Use to pull up.
[0042]
Since the lower end of the suspension spring 11 is fitted and held on the outer periphery of the suspension spring receiving portion 10b of the valve case 10, the valve case 10 is lifted as described above by lifting the suspension spring 11 as described above. It can detach | leave from the inner periphery of the attachment part 3a, and can take out easily from the vehicle body side tube 2 outside.
[0043]
Further, when replacing such parts, it is not necessary to drain the internal hydraulic fluid, and after replacing the parts, the suspension spring receiving portion 10b of the valve case 10 is fitted again to the lower end of the suspension spring 11, and these parts are connected to the vehicle body side. After being inserted into the tube 2 together with the spring guide, the cap 12 is attached to the upper end, so that reassembly can be performed quickly and easily.
[0044]
The attachment of the upper end of the vehicle body side tube 2 to the vehicle body is an operation above the vehicle body and is easy.
[0045]
Further, the spring 18 that supports the pressure side relief valve 17 is on the suspension spring 11 side, so that the flow area of the hydraulic oil that is the gap between the pressure side relief valve 17 and the check valve 16 can be sufficiently secured.
[0046]
As a result, the flow of the hydraulic oil during the extension stroke can be made smooth, and by providing the gap, the hydraulic oil is injected during assembly into the seat pipe 3 or the wheel side tube 1. This can be done while maintaining good wraparound.
[0047]
【The invention's effect】
As described above, the present invention has the following effects.
1) According to the invention of each claim, the valve case, the pressure side relief valve, the check valve, etc. are unitized and assembled in a cartridge type inside the lower end of the suspension spring, and in this state, the lower part of the valve case is seat pipe Therefore, the unitized valve case and the suspension spring can be easily removed from the upper end of the vehicle body side tube.
In particular, since the lower end of the suspension spring is held on the outer periphery of the suspension spring receiving portion formed on the upper portion of the valve case, the valve case is detached from the inner periphery of the upper end portion of the seat pipe by pulling up the suspension spring 11. Can be easily taken out from the vehicle body side tube.
[0048]
As a result, it is possible to quickly and reliably replace parts such as the relief valve and check valve in the valve case without draining the hydraulic oil in the seat pipe.
2) According to the invention of claim 2, the guide rod is erected at the center of the valve case, and the pressure side relief valve is inserted into the lower outer periphery of the guide rod so as to be movable up and down. Since the spring is interposed between the spring seat, the relief characteristic of the compression side relief valve according to the repulsive force of the spring can be obtained.
[0049]
Moreover, since the spring is provided along the guide rod, it does not interfere with the flow of hydraulic oil and does not adversely affect the flow of hydraulic oil.
3) According to the invention of claim 3, since the spring seat is screwed to the guide rod and the locking nut is screwed above the spring seat, the initial spring load of the spring can be adjusted according to the spring seat position. This provides the advantage that the damping force characteristic of the compression side relief valve can be arbitrarily adjusted.
[Brief description of the drawings]
FIG. 1 is a front view of a front fork according to an embodiment of the present invention, partially broken away.
FIG. 2 is an enlarged front view of a main part of the front fork shown in FIG.
FIG. 3 is a front view showing a conventional front fork partially cut away.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Wheel side tube 2 Vehicle body side tube 3 Seat pipe 6,15 Oil chamber 7 Upper port 8 Lower port 10 Valve case 13 Guide rod 14 Port 16, 25 Check valve 17 Pressure side relief valve 18 Spring 19 Spring seat 20 Loosening prevention nut 22 Lower part Oil chamber 27 Upper oil chamber

Claims (3)

The vehicle body side tube and the wheel side tube are slidably fitted, the seat pipe is erected in the center of the wheel side tube, the upper outer periphery of the seat pipe is slidably contacted with the inner periphery of the vehicle body side tube, and the outer side of the seat pipe is An upper oil chamber and a lower oil chamber separated by a check valve provided at the lower part of the vehicle body side tube are formed, an oil chamber is provided in the seat pipe, and this oil chamber is connected via a lower port formed in the seat pipe. A front fork with a suspension spring that communicates with the lower oil chamber and urges the body side tube in the direction of extension above the seat pipe holds the suspension spring receiving part formed at the top of the valve case at the lower end of the suspension spring It is allowed, and the lower portion of the valve case inserted into the inner periphery of the upper end of the seat pipe, forms a port in the valve case for communicating the oil chamber to the oil chamber of the reservoir-side Front fork, and is characterized in that a and the compression side relief valve and check valve at the outlet end of the port.  Claim that the guide rod is erected in the center of the valve case, the pressure side relief valve is inserted into the lower outer periphery of the guide rod so as to be movable up and down, and a spring is interposed between the pressure side relief valve and the spring seat above the guide rod. Item 1. Front fork.  3. The front fork according to claim 2, wherein a spring seat is screwed onto the guide rod, a locking nut is screwed above the spring seat, and the initial spring load of the spring is adjusted according to the position of the spring seat.

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