JPH059548Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a front fork with a built-in damper that is interposed between the body of a motorcycle or other vehicle and serves as a shock absorber and fork to damp vibrations from the road surface. .

[Conventional technology]

As this type of front fork, one in which a pressure valve and a variable orifice are provided in parallel, for example, as shown in FIG. 4, has been developed.

An inner tube is slidably inserted into an outer tube 1, a damper cylinder 3 stands up from the center of the bottom of one of the tubes 1, and a piston rod is inserted into the damper cylinder via a piston provided with a valve. This is a front fork with a built-in damper, in which a valve mechanism V is provided at the lower part of the damper cylinder 3.

The valve mechanism V includes a pressure valve 5 arranged on the outer periphery of a hollow support rod 4, an oil chamber 6 under the piston, and a reservoir 7.
It consists of a needle valve 9, which is a variable restrictor, provided in a passage 8 connecting the two.

In other words, the pressure valve 5 and the needle valve 9 constitute a valve mechanism provided in parallel in two passages connecting the piston lower oil chamber 6 and the reservoir 7, and each valve generates a compression side damping force. .

[Problem that the invention attempts to solve]

According to the conventional front fork described above, since the pressure valve 5 and the needle valve 9, which is a variable throttle, are provided in parallel, the pressure valve 5 has a damping force of the valve characteristic shown in graph a in FIG. 5 during compression operation. is obtained, and the damping force due to the orifice characteristics b, b' shown in graphs b, b'...n is obtained for the needle valve 9, but the characteristics synthesized from the two valves are the characteristics shown in graphs c, c'...n. I get used to it.

That is, in the low speed range, particularly in the very low speed range, only the characteristics along the orifice characteristics c, c'...n can be obtained, so the absorption of small vibration width is poor and the desired damping force cannot be obtained.

Furthermore, since the needle valve 9, which is a variable throttle, is provided along the axial direction at the lower end of the front fork, there is a problem that it cannot be applied to a center axle type device in which the mounting bracket is provided at the lower end of the front fork.

Therefore, the purpose of this invention is to provide a front fork with a built-in damper that generates the desired damping force even in the low speed range, can be adapted to center axle type front forks, and can improve suction performance when extended. be.

[Means for solving problems]

In order to achieve the above purpose, the configuration of the present invention is as follows:
An inner tube is slidably inserted into the outer tube, a damper cylinder is raised from the center of the bottom of one of the tubes, and a piston rod is movably inserted into the damper cylinder via a piston provided with a valve. In a front fork with a built-in damper, in which a reservoir is provided outside the damper cylinder, and two upper and lower oil chambers are partitioned within the damper cylinder by a piston, the passage connecting the lower oil chamber of the damper cylinder and the reservoir is A pressure side valve and a variable throttle are installed in series in the middle, and a bypass is also provided to connect the lower oil chamber of the damper cylinder and the reservoir. A check valve that opens when the cylinder is extended is installed in the middle of this bypass, and the variable throttle is connected to the opening area of the passage. It is characterized by comprising a needle valve that is rotatably and axially movable to adjust the outer tube, and that the needle valve is inserted from the lateral direction of the outer tube.

[Effect]

Since the pressure side valve and the variable throttle are arranged in series in the middle of the passage connecting the piston lower oil chamber and the reservoir, the combined damping force characteristics of the two valves generate the desired characteristics even in the low speed range. Since the variable aperture is adjusted from the lateral direction, even if a bracket is provided at the lower end of the front fork, it will not interfere with this bracket.

When the engine is extended, the check valve is pushed open from the bypass and the oil in the reservoir is sucked into the lower oil chamber.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

An inner tube 2 is inserted into the outer tube 1 so as to be slidable up and down, and a damper cylinder 3 and a hollow oil hole rod 10 are erected at the center of the lower part of the outer tube 1 via a support rod 4a. A piston rod 33 is movably inserted into the piston 32 via a piston 32 provided with a valve.
The piston 32 divides the damper cylinder 3 into an upper oil chamber 6a and a lower oil chamber 6b.

The support rod 4a is screwed into the damper cylinder 3 and stands up, and is pulled into the upper end of the base end 1a of the outer tube 1 by the bolt 11, and at this time, the damper cylinder 3 and the oil hole rod 10 are also fixed. .

On the outer periphery of the support rod 4a, a pressure side valve 1 is installed from below.
5, a disk 16, a check valve 17, a spring, and a valve holder 18 are inserted in series and tightened with a nut 19 at the upper end.

A pressure port 21 and an extension port 22 having an L-shaped cross section are formed in the disk 16. A leaf valve, which is a compression side valve 15, is provided at the lower mouth end of the pressure port 21 so as to be openable and closable. teeth,,
A check valve 17 is provided to be openable and closable, and each port 21 and 22 is connected to the piston lower oil chamber 6a, respectively.

Ports 25 and 26 that open to the oil chamber 14 and the port 21 are formed in the support rod 4a, and the port 26 has passages 28a and 28b formed in the bolt 11, and a passage 29 provided at the base end 1a of the outer tube 1.
30 and communicates with the reservoir 7 via a passage 31 provided in the oil hole rod 10.

A needle valve 32, which is a variable restrictor that is movable from the lateral direction in the rotational direction and the axial direction, is inserted into the base end 1a of the outer tube 1, and the tip poppet 32a of the needle valve 32 can be opened and closed with respect to the seat of the passage 29. The opening area of the passage 29 is adjusted.

A small hole 34 is formed in the poppet 32a and is a fixed throttle connecting the passages 29 and 30.

A through hole 35 is formed in the damper cylinder 3 so that the port 22 and the reservoir 7 communicate with each other.

During the extension operation, the inner tube 2 and piston 3
2 rises, and the lower oil chamber 6b of the damper cylinder 3
expands, and oil corresponding to the withdrawal volume of the piston rod 33 is introduced from the reservoir 7, the through hole 35, and the extension port 22 into the lower oil chamber 6b by pushing open the check valve 17.

The through hole 35 and the port 22 are used as a bypass, and because they directly suck oil from the reservoir 7, the oil suction performance is good, and there is no need to employ a complicated valve structure.

On the other hand, during the compression operation, the piston 32 descends and oil corresponding to the amount of oil entered by the piston rod 33 is returned to the reservoir 7.

At this time, the pressure side valve 15 is pushed open from the port 21 to generate a damping force characteristic of the valve.

Furthermore, from the oil chamber 14, ports 25, 26, passage 2
8a, 28b and the passage 29 on the poppet 32a of the needle valve 32.
The damping force of the orifice characteristic is generated by the restriction of the reservoir 7 through the passages 30 and 31.
leaks into

As shown in FIG. 3, the characteristics due to the pressure side valve 15 are shown in graph P, and the characteristics due to the variable throttle are shown in graphs Q1, Q2, Q3...Qn depending on the amount of restriction.
The characteristics of synthesis using both valves in series are shown by graphs R1, R2, R3...Rn.

Therefore, as can be seen from the graphs R1, R2, .

[Effect of idea]

As described above, according to the present invention, since the compression side valve and the variable throttle are provided in series, a damping force close to the valve characteristics is generated during compression operation even in the low speed range.

Therefore, the damping force can be adjusted to suit the road surface and driving conditions without impairing the absorbability of small oscillations.

Furthermore, the variable throttle needle valve is inserted into the outer tube from the lateral direction so that it can be adjusted freely, so it can be adjusted without interfering with the bracket provided at the lower end of the front fork, and it can also be installed on the vehicle body.

During extension, the oil from the reservoir is directly sucked in from the bypass, improving oil suction performance and eliminating the need for a complicated valve structure, allowing for simpler valve construction.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway longitudinal sectional front view of a front fork according to an embodiment of the present invention, Fig. 2 is a partially enlarged sectional view of Fig. 1, and Fig. 3 shows damping force characteristics according to the present invention. FIG. 4 is a graph showing the conventional front fork in a partially cutaway vertical cross-sectional view, and FIG. 5 is a graph showing the conventional damping force. Explanation of symbols, 1... Outer tube, 2...
Inner tube, 3... Damper cylinder, 6
b...Oil chamber, 7...Reservoir, 15...Pressure side valve, 17...Check valve, 21...Port,
25, 26, 28a, 28b, 29, 30...passage, 32...needle valve.

Claims (1)

[Claims for Utility Model Registration] (1) An inner tube is slidably inserted into an outer tube, and a damper cylinder is raised from the center of the bottom of one of the tubes,
A damper in which a piston rod is movably inserted into the damper cylinder via a piston equipped with a valve, a reservoir is provided on the outside of the damper cylinder, and two oil chambers, upper and lower, are partitioned into the damper cylinder by the piston. In the built-in front fork, a pressure side valve and a variable throttle are installed in series in the middle of the passage connecting the lower oil chamber of the damper cylinder and the reservoir, and a bypass is also installed to connect the lower oil chamber of the damper cylinder and the reservoir. A check valve that opens during expansion is provided in the middle of the bypass, and the variable throttle is configured with a needle valve that is movable in the rotational and axial directions to adjust the opening area of the passage, and the needle valve is inserted from the side of the outer tube. A front fork with a built-in damper. (2) Provide a bulkhead member at the bottom of the damper cylinder,
The partition wall member and the damper cylinder are provided with a port and a through hole to be used as a bypass, respectively, and a check valve is provided on the port end seat so as to be openable and closable.
Front fork with built-in damper as described in section. (3) The front fork with a built-in damper according to claim 1 of the utility model registration, wherein a fixed throttle is provided on the poppet of the needle valve. (4) Utility model registration in which a support rod is provided in the damper cylinder, a partition member is provided on the support rod, and a passage is provided between the partition member, the support rod, and the cylinder to connect the lower oil chamber of the damper cylinder and the reservoir. A front fork with a built-in damper according to claim 1.