JP3832890B2 - 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 an axle of a vehicle such as a motorcycle to attenuate vibrations from a road surface.
[0002]
[Prior art]
As this type of front fork, for example, one disclosed in Japanese Utility Model Laid-Open No. 4-17531 has been developed.
[0003]
In this front fork, an inner tube, which is a wheel side tube, is slidably inserted into an outer tube, which is a vehicle body side tube, via upper and lower bushes. A hollow rod is suspended from an upper end cap of the outer tube. The lower end piston portion is in sliding contact with the inner periphery of the inner tube via a piston ring that also serves as a check valve, and a valve provided inside the upper portion of the inner tube is in sliding contact with the outer periphery of the hollow rod. Further, a reservoir communicating with the reservoir in the hollow rod is formed between the outer tube and the hollow rod through a through hole provided with the hollow rod. Further, the expansion side damping force generating oil chamber is defined by the hollow rod, the inner tube, the valve, and the piston ring.
[0004]
In the compression operation, the front fork opens the piston ring, which also serves as a check valve on the outer periphery of the piston, to the expanding expansion damping force generating oil chamber, and the valve provided on the upper inner side of the inner tube. Stretching side damping force that contracts during expansion operation. The oil in the oil chamber is squeezed by an annular gap formed between the valve and the hollow rod and discharged to the reservoir inside the outer tube to generate damping force. It is supposed to be.
[0005]
[Problems to be solved by the invention]
In the above-described conventional front fork, the through hole that connects the reservoir in the outer tube and the reservoir in the hollow rod needs to be provided at a position above the valve even when the front fork is most compressed. During operation, there is a difference in the oil level between the reservoir in the outer tube and the reservoir in the hollow rod. That is, when the oil level of the reservoir in the outer tube reaches the position of the through hole formed in the hollow rod in the extended operation state, the amount of oil in the reservoir in the hollow rod decreases, and the oil level is near the piston part. Will be lowered.
[0006]
Therefore, when the compression operation is performed from this state, the piston ring that also serves as a check valve supplies oil near the oil surface containing a large amount of air to the expansion side damping force generation oil chamber, so the damping force is not stable. There is.
[0007]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a front fork capable of stabilizing a damping force by preventing oil shortage and air mixing even when the oil level of a reservoir in a hollow rod is lowered.
[0008]
[Means for Solving the Problems]
To achieve the object, means of the present invention, in the vehicle body side outer tube, the wheel-side inner tube is slidably inserted into the hollow rod and suspended from the top of the outer tube, the bottom of the hollow rod The provided piston part is in sliding contact with the inner periphery of the inner tube, the reservoir in the hollow rod communicates with the reservoir in the outer tube and the lower oil chamber in the inner tube, and the piston of the hollow rod is located inside the upper part of the inner tube. And a check valve that opens the piston side by compression and supplies oil from the lower oil chamber to the damping force generating oil chamber. in the front fork formed by providing, characterized in that the hollow pipes disposed on the inner diameter side than the check valve and vertically toward the lower oil chamber to the lower end portion of the hollow rod To.
[0009]
In this case, a damping force generating mechanism that generates damping force by allowing oil to pass from the lower oil chamber to the reservoir in the hollow rod during compression operation may be provided at the lower end of the hollow pipe. May be formed from a single pipe material.
Further, a spring seat portion may be provided below the hollow pipe.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. The front fork in FIG. 1 is an inverted front fork that is interposed between a vehicle body and an axle of a motorcycle and serves as a fork and a shock absorber.
That is, the front fork is provided with a wheel side inner tube 2 slidably inserted into a vehicle body side outer tube 1, a hollow rod 9 suspended from the upper portion of the outer tube 1, and a lower portion of the hollow rod 9. The piston part 10 is in sliding contact with the inner periphery of the inner tube 2, the reservoir A in the hollow rod 9 communicates with the reservoir B in the outer tube 1 and the lower oil chamber C in the inner tube 2, and the upper inner side of the inner tube 2 Includes an extension side damping valve 17 that forms a damping force generating oil chamber D with the piston portion 10 of the hollow rod 9, and opens the piston portion 11 by compression so that the lower oil chamber C A check valve 11 for supplying oil to the damping force generating oil chamber D is provided. And the hollow pipe 22 arrange | positioned in the lower end part of the hollow rod 9 from the said check valve 11 in the inner diameter side is suspended toward the said lower oil chamber C. As shown in FIG.
This will be described in more detail below.
[0011]
An inner tube 2, which is a wheel side tube, is slidably inserted into an outer tube 1, which is a vehicle body side tube, via bushes 3, 4 and an oil seal 5 provided on the inner circumference of the outer tube 1. The outer tube 1 is coupled to the vehicle body via upper and lower brackets, and the proximal end of the inner tube 2 is coupled to the axle via the eye 6.
[0012]
A cap 7 is screwed to the upper end of the outer tube 1, and a base end of the hollow rod 9 is detachably screwed to the center of the cap 7 via a screw 8 and is loosened by a nut 16.
[0013]
The lower end, which is the tip of the hollow rod 9 suspended from the cap 7, is provided with a piston portion 10 having an outwardly enlarged diameter. The check also serves as a piston ring that is fitted to the outer periphery of the piston portion 10 so as to be vertically movable. The valve 11 is in sliding contact with the inner periphery of the inner tube 2. On the other hand, an extension side damping valve 17 is provided on the upper inner periphery of the inner tube 2, and the extension side attenuation valve 17 is in sliding contact with the outer periphery of the hollow rod 9.
[0014]
The hollow rod 9 has an upper cylindrical portion 9a that is reduced in diameter and screwed into the cap 7 and the nut 16, an intermediate main body portion 9c that is connected to the lower portion of the upper cylindrical portion 9a via a tapered portion 9b, and a main body portion 9c. It is comprised by the piston part 10 provided in a row by the lower end of this, and the upper and lower oil holes 13 and 14 formed in the main-body part 9c.
[0015]
A cushion rubber 15 is fitted on the outer periphery of the tapered portion 9b of the hollow rod 9, and is detachably held between the nut 16 and the tapered portion 9b. In this case, the diameter of the nut 16 is formed larger than the diameter of the inner tube 2, and the nut 16 engages with the bush 3 when the fastening portion between the cap 7 and the hollow rod 9 is disassembled.
[0016]
A hollow spacer 18, a stopper 19, and a valve housing 20 are fitted inside the upper end portion of the inner tube 2, and an extension side damping valve 17 urged in a closing direction by a spring moves up and down in the valve housing 20. It is inserted freely, and the outer periphery of the extension side damping valve 17 is in sliding contact with the outer periphery of the hollow rod 9 through an arbitrary gap.
[0017]
A hollow pipe 22 extending downward from the piston portion 10 is connected to the hollow rod 9. The hollow pipe 22 is disposed on the inner diameter side of the check valve 11, and a lower oil chamber C is provided outside and below the hollow pipe 22.
[0018]
In this case, an annular ring member 23 is attached to the outer periphery of the upper end of the hollow pipe 22, and the hollow pipe 22 is connected to the hollow rod 9 by fitting or welding the ring member 23 to the piston portion 10 of the hollow rod 9. ing. In the lower part of the hollow pipe 22, that is, in the center of the lower end, an orifice 26 as a compression side damping force generating mechanism is formed.
[0019]
The hollow rod 9 and the hollow pipe 22 may be formed from a single pipe material . In this case, the cost can be reduced by reducing the number of parts. In this case, the piston portion 10 may be integrally formed or may be inserted later into the outer periphery of the pipe material.
[0020]
A support pipe 24 stands on the proximal end side of the inner tube 2, and a suspension spring 25 is interposed between the seat portion on the support pipe 24 and the ring member 23, and the suspension spring 25 is always a hollow rod. 9 and the outer tube 1 are urged in the extending direction.
[0021]
A reservoir A composed of an oil chamber and a gas chamber is defined in the hollow rod 9, and an upper reservoir B is defined between the outer tube 1 and the hollow rod 9. Oil chamber C is partitioned. Further, between the inner tube 2 and the hollow rod 9, there is provided an oil chamber D for generating an extension side damping force defined by the extension side damping valve 17 and the check valve 11, and in this oil chamber D is a cushion. A spring 27 is provided.
[0022]
Between the outer tube 1 and the inner tube 2 is provided an oil chamber E for lubrication defined by upper bushes 3 and 4, and this oil chamber E is located below through an oil hole 28 provided in the inner tube 2. To the oil chamber C.
[0023]
The reservoir A and the reservoir B in the outer tube 1 communicate with each other through oil holes 13 and 14, and the reservoir A and the lower oil chamber C communicate with each other through an orifice 26 provided in the hollow pipe 22.
[0024]
Further, the oil chamber D is opened and closed to the lower oil chamber C via a notch 11 a formed in the check valve 11, and similarly opened and closed to the upper reservoir B via the expansion side damping valve 17.
[0025]
The state shown in FIG. 1 is the most extended state, but when compression is performed from this state, the oil in the lower oil chamber C flows into the reservoir A through the orifice 26, and a compression side damping force is generated by the flow resistance at this time. To do. A part of the compressed oil in the upper reservoir B flows out to the reservoir A through the oil holes 13 and 14.
[0026]
The expanding oil chamber D is replenished with a part of the oil in the reservoir B by opening the expansion side damping valve 17, and further, the oil chamber C in the lower oil chamber C is passed through the notch 11a of the check valve 11 pushed upward. Oil is supplied.
[0027]
Next, when switching to the extension operation, the oil in the reservoir A is supplied to the oil chamber C below the orifice 26 through the hollow pipe 22, and the oil level is lowered. Further, the expansion side damping valve 17 and the check valve 11 are closed, and the oil in the oil chamber D flows out into the upper reservoir B through the inner circumferential clearance of the expansion side damping valve 17 pushed upward. The extension side damping force is generated by the flow resistance of the inner circumferential clearance 17.
[0028]
In the above operation, when the oil level of the reservoir B reaches the oil hole 13, the amount of oil in the reservoir A decreases and the oil level descends, but the reservoir A is located on the outside by the hollow pipe 22. Since the piston ring that also serves as the check valve 11 is isolated from the lower part of the piston ring, the oil mixed with the air near the oil level of the reservoir A is not supplied to the oil chamber D by the compression operation. Damping force is stabilized.
[0029]
Further, the orifice 26 and the like as a compression side damping force generating mechanism are provided below the hollow pipe 22 and are located away from the oil level of the reservoir A, so that oil mixed with a lot of air near the oil level passes through. There is no damping and the damping force is stabilized.
[0030]
On the other hand, since the cushion rubber 15 is fitted into the tapered portion 9b and is held between the nut 16 and the tapered portion 9b, the cushion rubber 15 can be easily attached and detached, and the structure is simplified. In addition, the cushion rubber can be assembled after injecting oil at the time of assembling the front fork, so that the lubrication operation is simple and the lubrication time can be shortened.
[0031]
Since the nut 16 is set to be larger than the diameter of the inner tube 2, when the front fork is disassembled, the cap 7 is first removed, and then the outer tube 1 is lifted to remove the nut 16 from the upper and lower bushes 3 and 4 and the oil. The bushes 3 and 4 and the oil seal 5 can be pulled out while the nut 16 is coupled to the hollow rod 9 if it is pulled up as it is, and the disassembling operation is improved. To do.
[0032]
FIG. 3 shows another embodiment of the present invention, in which a hollow pipe 22a is suspended below the hollow rod 9, and the lower end portion or the vicinity of the lower end portion of the hollow pipe 22a is reduced in diameter toward the inner diameter side. Thus, an orifice 26a is provided as a spring seat portion 30 and a damping force generating mechanism, and a suspension spring 25a is interposed between the spring seat portion 30 and the base end upper surface of the inner tube 2. In this case, compared to the embodiment of FIG. 1, the support pipe 24 is not required, and the spring seat portion 30 and the orifice 26a can be integrated and easily formed by reducing the diameter of the hollow pipe 22a, so that the structure is simple. This is advantageous in terms of workability, assembly, and economy.
[0033]
【The invention's effect】
The present invention has the following effects.
[0034]
(1) According to the invention of each claim, since the hollow pipe is continuously provided below the hollow rod, the lower part of the check valve is defined as the hollow pipe even if the oil level of the reservoir in the hollow rod is lowered. Therefore, it is possible to prevent a shortage of oil and air from entering the expansion side damping force generating oil chamber, thereby stabilizing the damping force.
[0035]
(2) According to the invention of claim 2, since the compression side damping force generation mechanism can be separated from the reservoir oil surface in the hollow rod, the oil mixed with a large amount of air near the oil surface is caused by this pressure side damping force generation mechanism. Since it does not pass, the damping force is stabilized.
[0036]
(3) According to the invention of claim 3, since the hollow rod and the hollow pipe are integrally formed and the number of parts can be reduced, it is advantageous in terms of cost.
[0037]
(4) According to the invention of claim 4, there is no need for a support pipe for supporting the suspension spring, which is advantageous in terms of weight and cost, and since the suspension spring is disposed deep in the oil, air is mixed into the oil. Can be suppressed.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view of a front fork according to an embodiment of the present invention.
FIG. 2 is a partially enlarged cross-sectional view of FIG.
FIG. 3 is a longitudinal front view of a front fork according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 9 Hollow rod 10 Piston part 11 Check valve 17 Extension side damping valve 22, 22a Hollow pipe 26 Orifice A, B Reservoir C Oil chamber

Claims (4)

A wheel side inner tube is slidably inserted into the vehicle body side outer tube, a hollow rod is suspended from the upper portion of the outer tube, and a piston portion provided at the lower portion of the hollow rod is in sliding contact with the inner periphery of the inner tube, A reservoir in the hollow rod communicates with a reservoir in the outer tube and a lower oil chamber in the inner tube, and a damping force generating oil chamber is formed inside the upper portion of the inner tube between the piston portion of the hollow rod. In the front fork comprising a side damping valve and a check valve that opens the piston portion by compression and supplies oil from the lower oil chamber to the damping force generating oil chamber, the lower fork of the hollow rod A front fork characterized in that a hollow pipe disposed on the inner diameter side of the check valve is suspended toward the lower oil chamber . The front fork according to claim 1, wherein a damping force generating mechanism is provided at the lower end portion of the hollow pipe to generate a damping force by allowing oil to pass from a lower oil chamber to a reservoir in the hollow rod during compression operation. The front fork according to claim 1, wherein the hollow pipe and the hollow rod are formed from a single pipe material .  4. The front fork according to claim 1, wherein a spring seat portion is provided below the hollow pipe.

Images