JP2003247584A - Front fork - Google Patents

Abstract

(57) [Abstract] [Problem] A bearing can be firmly fastened and fixed to prevent backlash and loosening of a bush and an oil seal inside the bearing.
It is another object of the present invention to provide a front fork with a built-in damper, in which a fastening force to a bearing does not adversely affect a bending characteristic of a relief valve. A locking step (9) is provided on an outer periphery of a bearing (20), a locking surface (b) facing the locking step is formed on an inner circumference of a cap member (49), and a washer (50) is provided on an upper end of a damper cylinder (9). And the cap member 4
The washer 50 and the bearing 20 are sandwiched between the locking surface and the upper end portion of the damper cylinder 9 while the screw 9 is screwed to the outside of the damper cylinder 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork for a motorcycle that elastically supports a front wheel of a motorcycle with respect to a vehicle body and absorbs vibrations of the vehicle body, and more particularly to an outer tube and an inner tube that are inserted and removed freely. The present invention relates to a front fork with a built-in damper in which a damper for generating a damping force is interposed.

[0002]

2. Description of the Related Art As a front fork of this type, for example, one disclosed in Japanese Patent Laid-Open No. 10-292842 has been developed.

This front fork suppresses only the damping characteristic in the low speed region during the compression operation without affecting the extension side and compression side damping characteristics, thereby preventing the occurrence of bottoming and improving the riding comfort. And its structure is shown in FIG.
It has the configuration shown in.

That is, a piston 10 having an extension side damping valve 13 and a compression side rear valve 14 is provided inside a damper cylinder 9 having a compression side damping valve 17 and extending between an outer tube 1 and an inner tube 2 which are inserted and removed freely. The damper 5 which is divided into the expansion side hydraulic oil chamber T and the compression side hydraulic oil chamber C is interlocked so as to be capable of expanding and contracting in synchronization, and the space between the outer tube 1 and the inner tube 2 and the damper 5 is reserved as a reservoir. A chamber R is provided, and the expansion side hydraulic oil chamber T in the damper 5 is further opened through a relief valve 35 which is opened by the oil pressure in the expansion side hydraulic oil chamber T in the low speed range during the compression operation as well as during the expansion operation. -I made it communicate with room B.

In this case, the bearing 20 having the relief valve 22 and the oil passage 36 and the washer 40 are arranged in series in the cap member 19, and the bush 25a and the oil seal 26a, which are in sliding contact with the piston rod 4, are provided in the bearing 20. Is provided.

[0006] The relief valve 22 and the bearing 20.
The washer 40 is held by crimping the lower end of the cap member 19, and the cap member 19 is screwed to the inner circumference of the upper end portion of the damper cylinder 2.

In the above-mentioned conventional front fork, the damping characteristic at the time of extension operation is the extension side damping valve 13 of the piston 10 and the relief valve 22, and the damping characteristic at the time of compression operation is the compression side damping valve 17 of the cylinder-bottom and the piston. 1
Even if the back valve 14 of 0 is set to a predetermined expansion damping characteristic, the relief valve is used even in the low speed range during compression operation in which the oil pressure in the expansion side hydraulic oil chamber T is higher than in the high speed range. 22 will open.

From this, while the damping characteristics of both the expansion side and the compression side damping valves 13 and 17 can be independently set, the oil in the expansion side hydraulic oil chamber can be set in the low speed range during the compression operation. From the relief valve 22 to the reservoir chamber R, and the pressure-side damping valve 17 is pushed open accordingly and the flow rate of the oil pushed out to the reservoir chamber R is reduced to reduce the damping in the low speed region during the pressure-side operation. Only lower the characteristics,
It is also possible to improve the riding comfort as a motorcycle.

[0009]

The above-mentioned conventional front fork has the above-mentioned remarkable functions and effects, but it is desired to improve the following problems.

First, since the relief valve 22 and the bearing 20 are caulked and fixed by the cap member 19, the ease of opening the relief valve 22 varies depending on the caulking force (axial force), and the damping characteristics vary. Is likely to occur.

That is, if the axial force is weak, the relief valve is likely to open and the damping force is lower than desired. On the contrary, if the axial force is strong, the relief valve 22 is difficult to open and the damping force is higher than the desired damping force. After all, depending on the magnitude of the caulking force at the time of assembling, different products have different damping force characteristics, and accuracy control is very difficult.

Second, the bush 25a and the oil seal 2
In order to firmly fix 6a in the bearing 20 without slack, the bearing 20 itself must be firmly fixed.

Therefore, the axial force due to the caulking may be increased by the cap member 19, but as described above, the axial force affects the flexural characteristics of the relief valve 22.

Therefore, an object of the present invention is to firmly fasten and fix the bearing to prevent backlash and looseness of the bushes and oil seals inside thereof, and at the same time, the fastening force on the bearing adversely affects the flexural characteristics of the relief valve. It is to provide a front fork without a damper.

[0015]

In order to achieve the above-mentioned object, the means of the present invention is such that an inner tube is slidably inserted into an outer tube, a damper cylinder is erected in the inner tube, and A cap member is provided at the end, a bearing having an oil passage in the cap member and a relief valve for opening and closing the oil passage are provided in series, and a bush and an oil seal are provided in series inside the bearing, and a damper is provided. The piston rod is movably defined in the cylinder through the piston, the bush, and the oil seal, and divides the expansion-side oil chamber and the compression-side oil chamber, and the expansion-side oil chamber communicates with the reservoir through the oil passage and the relief valve. In the front fork, the locking step is provided on the outer circumference of the bearing, and the locking surface facing the locking step is formed on the inner circumference of the cap member. A bearing is disposed on the upper end of the damper cylinder via a washer, and the washer and the bearing are sandwiched between the locking surface and the upper end of the damper cylinder while the cap member is screwed onto the outside of the damper cylinder. It is a thing.

In this case, a plurality of shims and leaf springs may be laminated on the outer peripheral side upper surface of the relief valve, and an annular groove may be formed in the upper wall of the cap member facing the outer peripheral side upper surface of the leaf spring.

Further, in each of the above means, it is preferable that friction generating members are provided on the outer circumference of the bearing and the inner circumference of the cap member.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The front forks according to the embodiments of FIGS. However, the basic structure of the whole is the same as the conventional example of FIG.

That is, as can be seen from the drawings, the outer tube 1 and the inner tube 2 which are inserted and removed freely, and the cylinder bottom 3 of the damper 5 and the piston 10 which are housed therein, are configured as follows. There is no difference from the case of FIG. 3 described above.

Therefore, here, in order to eliminate the complexity of the description due to the repetition, the damper 3 different from FIG. 3 is used.
Only the portion of the cylinder head 6 will be described, and the configuration of the other portions will be omitted because it can be easily understood by assigning the same reference numerals to the same members as in FIG.

In the front fork according to the embodiment shown in FIG. 1, as in the front fork shown in FIG. 3, the inner tube 2 is slidably inserted into the outer tube 1 and the damper cylinder 9 is inserted into the inner tube 2. Is standing up.

A cap member 49 is provided at an end of the damper cylinder 9, and a bearing 20 having an oil passage 36 in the cap member 49, a relief valve 22 for opening and closing the oil passage 36, and a shim for supporting the relief valve 22 are provided. 51 is provided in series, and the bush 25a is provided inside the bearing 20.
And the oil seal 26a are provided in series.

Further, the piston 1 is placed in the damper cylinder 2.
0, the bush 25a and the oil seal 26a, the piston rod 4 is movably inserted, and the piston 1
0 is the expansion side oil chamber T and the compression side oil chamber C in the damper cylinder 9.
And the expansion side oil chamber T communicates with the reservoir R via the oil passage 36 and the relief valve 22.

Further, in the present invention, a locking step portion a is provided on the outer circumference of the bearing 20 and a locking surface b facing the locking step portion a is formed on the inner circumference of the cap member 49, and the damper cylinder 9 is provided.
The bearing 20 is disposed at the upper end of the washer 50 via the washer 50, and the lower cylinder portion 49a of the cab member 49 is screwed onto the outside of the damper cylinder 9 to secure the washer 50 and the bearing 20 to the locking surface b and the damper cylinder 9. It is sandwiched with the upper end.

As described above, according to the present invention, since the bearing 20 and the washer 50 are sandwiched between the locking surface b and the upper end portion of the damper cylinder 9, the lower cylindrical portion 20a of the cap member 49 is held against the damper cylinder 2. Even if they are tightly screwed together and tightened, the locking surface b only presses against the locking step a, and the cab member 49 does not descend further.

Therefore, the tightening force of the cap member 49 does not act on the shim 51 and the relief valve 22, does not affect the flexural characteristic of the relief valve 22, and can always generate a predetermined damping force characteristic.

In other words, in accordance with the dimension A between the upper end surface of the shim 51 and the locking step portion a, the distance between the upper wall surface d of the cap member 49 and the locking surface b is matched with this dimension A in advance. By controlling so that the relief valve 22 holds the cap member 49 against the bearing 20 (axial force).
Can be prevented from being transmitted.

On the other hand, since the bearing 20 is firmly sandwiched between the locking surface a and the upper end of the damper cylinder 2 as described above, it is possible to prevent looseness and looseness of the bush 25a and the oil seal 26a on the inner circumference of the bearing. .

Further, in the present invention, a friction generating member such as an O-ring 52 made of rubber or the like is provided on the outer periphery of the bearing 20.

The O-ring 52 generates friction between the O-ring 52 and the cap member 49, so that the shim 51, the relief valve 22 and the bearing 20 are inserted into the cap member 49 so that each of these parts does not drop during assembly. It can be temporarily stopped. The other overall structure, operation, and effect will be described in detail below.

Cylinder head 6 of damper cylinder 9
The cap member 49 and the piston rod 4 to the bearing 2
The cap member 49 is attached to the damper cylinder 9 by screwing it into the damper cylinder 9 by sandwiching the shim 51 and the relief valve 22 between them.

In this case, the cap member 49 is
Shim 51 and relief valve 22 between bearing 20
It is configured as a simple nut body having a large diameter hole 23 in the center for sandwiching and fixing.

On the other hand, the bearing 20 comprises a bush 25a capable of self-aligning on the inner peripheral surface and an oil seal 26a arranged in series with the bush 25a, and the piston rod 4 is slidable by the bush 25a. The oil seal 26a keeps the space between the piston rod 4 and the piston rod 4 oily.

Further, the oil in the expansion side oil chamber T is applied from the oil passage 27 of the bearing 20 to the fixed portion 35 which is the sandwiching portion of the relief valve 22, and the fixed portion 35 changes the direction of the oil flow before the bearing 20. The bent oil passage 36 is configured to push open the relief valve 22 through the step 28.

With such a configuration, the oil flow from the expansion side oil chamber T becomes a jet flow and the relief valve 22 is directly connected.
And the relief valve 22 is pushed open only by the oil pressure in the extension side oil chamber T without being affected by the momentum of the jet flow, so that stable damping characteristics can be obtained. .

Further, the washer 50 disposed adjacent to the bearing 20, like the bearing 20, holds the buffer spring 33 that abuts the piston holder 32 of the piston rod 4 when the damper 5 is extended, and cushions the shock. The extension side working oil chamber T is guided to the oil hole 27 of the bearing 20 through the oil hole 34 formed in the washer 50 and the oil passage 34a formed in the lower portion of the oil seal 26a.

In this way, the expansion side oil chamber T in the damper 5 passes through the oil passages 34, 34a, the oil hole 27, the relief valve 22, and the large diameter hole 23 of the cap member 19.
Through to the reservoir chamber R outside the damper 5.

Next, the piston 10 is formed with the expansion side port 11 and the compression side port 12 as in the conventional example of FIG. 3, and the expansion side damping valve 13 is provided at the outlet end of the expansion side port 11.
At the outlet end of the pressure side port 12, a pressure back surface valve 14 is provided so as to be opened and closed. Further, the piston rod 4 is provided with bypasses 53, 54 and a needle valve 55 for adjusting the opening area of the bypasses 53, 54.

Further, although not shown, as in the case of FIG. 3, the ports 15, 16 are provided at the bottom of the damper cylinder 20.
A compression side damping valve 17 and a check valve 18 for opening and closing these are provided so as to be openable and closable.

During the expansion operation of the front fork, the damper 5 is expanded together with the expansion operation, and the piston 10 reduces the volume of the expansion side oil chamber T and pressurizes the oil inside to expand the inside of the expansion side hydraulic oil chamber T. The expansion side damping valve 13 is pushed open from the port 11 of the piston 10 into the pressure side hydraulic oil chamber C. At the same time, oil flows through the bypasses 53 and 54.

Further, in addition to the above, the oil in the expansion side oil chamber T is pushed open to the reservoir chamber R by pushing open the relief valve 22 also from the oil passage 27 of the bearing, and the relief valve 22 and the above-described extension. The extension side damping force is generated by the flow resistance of the oil when the side damping valve 13 is pushed open to flow and the flow resistance of the bypasses 53 and 54.

At this time, the shortage of the oil generated in the pressure side oil chamber C due to the withdrawal of the piston rod 4 from the damper cylinder 9 causes the check valve 18 to be opened from the port 16 of the cylinder bottom 3 and the inside of the reservoir chamber R to be opened. It is guaranteed by sucking the oil into the pressure side oil chamber C.

On the other hand, during the pressure side operation, the volume of the pressure side oil chamber C of the damper 5 is reduced, and the oil inside is pushed into the expansion side working oil chamber T by pushing the rear valve 14 from the port 12 of the piston 10. Push out and bypass 53.5 at the same time
Oil flows from 4 as well, and the back surface valve 14 controls the oil pressure in the expansion side oil chamber T in accordance with the compression speed.

In parallel with this, an amount of oil that cannot fully enter the expansion side oil chamber T due to the penetration of the piston rod 4 into the damper cylinder 9 is attenuated from the compression side oil chamber C through the port 15 of the cylinder bottom 3 on the compression side. The valve 17 is pushed open into the reservoir chamber R, and the compression damping valve 17 is pushed open to generate a compression damping force by the flow resistance of the oil flowing.

In this manner, the extension side damping valve 13 and the relief valve 22 are pushed open during the extension operation, and the compression side damping valve 17 is opened during the compression side operation to generate the extension side and compression side damping forces. Therefore, the extension side damping force and the compression side damping force can be set to individual damping characteristics.

In addition, the oil pressure in the expansion side oil chamber T controlled by the rear side valve 14 during the compression operation follows the compression speed and pushes the rear side valve 14 from the pressure side oil chamber C to open the rear side oil chamber T. It is high in the low speed range where the flow of oil toward the side is relatively easy, and lower than it in the high speed range where the followability of the oil flow deteriorates.

From this, the relief valve 22 is pushed and opened not only by the oil pressure of the extension side oil chamber T applied during the extension operation but also by the oil pressure applied to the extension side oil chamber T in the low speed range during the compression operation. Set to.

As a result, the damping characteristic at the time of extension operation is set individually by the extension side damping valve 13 of the piston 10 and the relief valve 22, and the damping characteristic at the time of compression operation is set individually by the pressure side damping valve 17 of the cylinder bottom 3. The relief valve 22 is opened even in the low speed range during the compression operation in which the oil pressure in the expansion side oil chamber T is higher than that in the high speed range while maintaining the predetermined compression and damping characteristics.

In this way, the expansion-side damping valve 13 and the compression-side damping valve 17 can independently set the damping characteristics of both the expansion and the expansion-side operation during the compression operation in the low speed range. The oil in the oil chamber T is pushed out of the relief valve 22 into the reservoir chamber R.

As a result, during the compression operation in the low speed region, the compression side damping valve 17 is pushed open by the amount of oil pushed out from the relief valve 22 into the reservoir chamber R and pushed out into the reservoir chamber R. The oil flow rate is reduced, and only the damping characteristic in the low speed region during the compression operation is lowered, so that the occurrence of bottoming is prevented and the riding comfort of the motorcycle is improved.

In addition to this, even if air or oil containing air is sucked into the damper 5 from the reservoir chamber R as the damper 5 expands and contracts, the air or oil containing air is relieved by the relief valve. Since it is immediately returned to the reservoir chamber R by pushing open the valve 22, it is possible to prevent the occurrence of aeration in the damper 5 and always secure a stable damping characteristic.

Next, FIG. 2 shows another embodiment of the present invention in which a leaf spring 57 is provided so as to face the outer peripheral side upper surface of the shim 51, and an annular groove 56 is formed in the upper wall of the cap portion 49. It is a thing.

In this case, a load can be applied to the leaf spring 57 and the relief valve 22, and an arbitrary load can be obtained by changing the plate thickness, the number of sheets, and the bending amount of the leaf spring 57.

[0054]

The present invention has the following effects.

According to each of the claimed inventions, since the relief valve, the bearing and the washer are sandwiched between the upper end of the damper cylinder and the engaging surface of the cap member, the cap member is screwed to the damper cylinder. Even if tightened tightly, the stroke of the cap member is restricted by the bearing-side locking step with which the locking surface abuts, and there is no excess axial force acting on the relief valve, so the relief valve's deflection characteristics can always be kept constant. As a result, it is possible to prevent variations in the damping force of each product.

Similarly, since the bearing is clamped and firmly fixed as described above, it is possible to prevent the bushes and oil seals provided inside from rattling and loosening.

Similarly, since the relief valve and the bearing are sandwiched as described above, and the cap member is screwed to the damper cylinder and is not fixed by crimping, the assembling property is improved and the economy is excellent.

According to the invention of claim 2, a plurality of shims and leaf springs are provided on the upper surface side of the relief valve, and an annular groove is formed in the upper wall of the cap member so as to face the outer peripheral side upper surface of the leaf spring. Therefore, when the cap member is fastened, the leaf spring can be brought into contact with the leaf spring while being bent, and as a result, an arbitrary load can be obtained for the relief valve by changing the plate thickness, the number of sheets, and the amount of bending of the leaf spring.

According to the invention of claim 3, since the friction generating member is provided between the bearing and the cap member, even if the relief valve and the bearing are previously inserted into the cap member at the time of assembling, these members are also provided. Can be prevented from falling off, and the assemblability is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a main part of a damper built-in front fork according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view showing a main part of a front fork with a built-in damper according to another embodiment of the present invention.

FIG. 3 is a vertical sectional front view showing a main part of a conventional front fork with a built-in damper.

[Explanation of symbols]

a Locking surface b Locking step C pressure side oil chamber T side oil chamber R reservoir chamber 1 Outer tube 2 Inner tube 5 damper 7 Suspension spring 9 damper cylinder 10 pistons 13 Extension side damping valve 14 Rear valve 17 Pressure side damping valve 18 check valve 20 bearings 22 Relief valve 25a bush 26a Oil seal 27 oil passage 36 Bent Oil Path 49 Cap member 50 washers 51 Sim 56 annular groove 57 Leaf Spring

Claims (3)

[Claims] 1. An inner tube is slidably inserted into an outer tube, a damper cylinder is erected in the inner tube, a cap member is provided at an end of the damper cylinder, and an oil passage is provided in the cap member. A bearing and a relief valve that opens and closes this oil passage are provided in series, a bush and an oil seal are provided in series inside the bearing, and the piston rod is freely movable in the damper cylinder via the piston and the bush and oil seal. The piston divides the expansion-side oil chamber and the compression-side oil chamber in the damper cylinder, and the expansion-side oil chamber communicates with the reservoir via the oil passage and the relief valve. A locking step is provided on the outer circumference of the damper member, and a locking surface facing the locking step is formed on the inner circumference of the cap member. A front fork characterized in that a bearing is disposed on the upper end of the damper through a washer, and the washer and the bearing are sandwiched between the locking surface and the upper end of the damper cylinder while the cap member is screwed onto the outer periphery of the damper cylinder. 2. A relief valve, wherein a plurality of shims and leaf springs are laminated on the outer peripheral side upper surface, and an annular groove is formed in the upper wall of the cap member facing the outer peripheral side upper surface of the leaf spring. Front fork 3. The front fork according to claim 1 or 2, wherein a friction generating member is interposed between the outer circumference of the bearing and the inner circumference of the cap member.