JPH0523863Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a front fork that suspends the front wheel of a motorcycle, etc. More specifically, this invention relates to a front fork that suspends the front wheel of a motorcycle, etc. Regarding the front fork with a built-in damper.

[Conventional technology]

Conventionally, this type of inverted front fork with a built-in damper has an inner tube that supports the front wheel slidably inserted into an outer tube connected to the vehicle body, and the damper is inserted from the center of the bottom of the inner tube into the inner tube. While the cylinder is erected, the damper cylinder has a piston with a damping force generating mechanism inside, and the tip of a piston rod extending outward from the piston is connected to the upper end of the outer tube, A reservoir chamber is formed between the damper cylinder and the damper cylinder, and the reservoir chamber and the damper cylinder communicate with each other through an oil hole provided below the damper cylinder.

By the way, in order to provide such a front fork with a cushioning function that alleviates the shock that occurs at the maximum compression, for example, it is necessary to use the following methods: Utility Model Application Publication No. 102791 of 1988 and Utility Model Application Publication No. 26310 of 1963. As seen in the publication, a hollow oil lock case is raised from the center of the bottom of the damper cylinder, and an oil lock piece that fits into the oil lock case is provided at the lower end of the piston rod, facing the oil lock case. By fitting the oil lock piece into the oil lock case near the maximum compression of the front fork and pushing out the internal hydraulic oil through the fitting gap between the oil lock case and oil lock piece, the flow resistance of the hydraulic oil at that time is reduced. All you have to do is use it to generate a cushioning effect.

[Problem that the invention attempts to solve]

However, in the case of a front fork equipped with the above-mentioned cushioning mechanism, although the oil lock case and oil lock piece are fixed concentrically to the damper cylinder and piston rod, respectively, the compression of the front fork is When the oil lock case and oil lock piece fit together during operation, it is impossible for the oil lock piece fixed to the piston rod side to fully operate concentrically with respect to the oil lock case. The outer peripheral surface of the oil lock case will interfere with the inner peripheral surface of the oil lock case.

If the oil lock case and the oil lock piece are eccentric and cause uneven contact in this way, the oil lock characteristics are impaired, and at the same time burrs are generated, which may impair the vibration damping function of the oil damper itself.

Furthermore, when the front fork moves to extension after the above-mentioned cushioning action ends, the oil lock piece moves in the direction of coming out from the oil lock case, creating negative pressure inside it, which can cause abnormal noise when the two are separated. become.

In order to prevent this, in the case of the above-mentioned Utility Model Application Publication No. 26310 of 1963, a check valve that opens into the oil lock case is provided for the oil lock case that stands up from the damper cylinder side. By sucking hydraulic oil into the oil lock case through this check valve, negative pressure is prevented as much as possible.

Therefore, in this case, a portion of the hydraulic oil sucked from the reservoir chamber into the lower piston chamber in the damper cylinder is drawn into the oil lock case from the check valve.

However, the hydraulic oil in the reservoir chamber contains a large amount of gas above the reservoir chamber due to fluctuations in the oil level due to the expansion and contraction of the front fork, and this gas precipitates from the hydraulic oil in the oil lock case where the pressure is almost negative. Since the damper enters the damper, it has the disadvantage that the damping effect of the damper tends to vary.

Therefore, even if there is eccentricity between the oil lock case and the oil lock piece, this invention always allows them to self-align and fit together smoothly, and when the oil lock case and oil lock piece come out, An object of the present invention is to provide an improved cushioning device for a front fork of this type that can suck hydraulic oil containing as little gas as possible into an oil lock case and an oil lock piece.

[Means for solving problems]

In order to achieve the above object, the structure of this invention is such that a hollow oil lock case is raised from the lower part of the damper cylinder, a hollow oil lock piece that fits into the oil lock case is provided on the lower end side of the piston rod, and The oil lock case is connected to the damper cylinder so as to be able to move laterally and tilt while maintaining a floating state, and a check valve is located at the base end of the oil lock piece and opens into the oil lock piece. It is characterized by the fact that

<Function> As a result, even if there is eccentricity between the oil lock case and the oil lock piece, the oil lock case is automatically aligned with the oil lock piece near the maximum compression of the front fork, and the two always fit together smoothly. However, the hydraulic oil flows into the interior through the gap between the inner circumferential surface of the oil lock case and the outer circumferential surface of the oil lock piece, and a stable cushioning action is performed due to the flow resistance of the hydraulic oil passing through the gap.

In addition, when the oil lock case and oil lock piece are extended apart from each other, a check valve for suctioning hydraulic oil is provided at the base end of the oil lock piece attached to the piston rod side, so that the damper cylinder has a chamber above the piston. A part of the hydraulic oil that has been pushed out from the piston to the lower chamber of the piston through the expansion-side damping force generating valve is sucked into the oil lock case and oil lock piece through the check valve.

In this case, the hydraulic oil that is pushed out from the piston upper chamber is compressed in the piston upper chamber and is pushed out into the piston lower chamber in the form of gas separation, and this hydraulic oil, which contains almost no gas, is transferred to the oil lock case. The gas will be sucked into the oil lock piece, and therefore, almost no gas will be deposited from the hydraulic oil inside the two.

〔Example〕

An example of implementing this invention will be described below based on the drawings.

An inner tube 2 is slidably inserted into an outer tube 1, a damper cylinder 3 stands up from the center of the lower part of the inner tube 2, and a piston 4 is slidably inserted into the damper cylinder 3. The tip of a piston rod 5 extending outward from the piston 4 through the upper end of the damper cylinder 3 is connected to the upper end of the outer tube 1.

Inner tube 2 from outer tube 1
The space between the damper cylinder 3 and the piston 3 is a reservoir chamber 7 filled with hydraulic oil and has a gas portion at the upper part. 9
The lower piston chamber 9 is divided into a base valve 10.
The oil hole 36 bored in the damper cylinder 3 through the damper cylinder 3 communicates with the reservoir chamber 7.

The piston 4 is formed with an expansion side port 11 and a compression side port 12. At the lower mouth end of the expansion side port 11, there is an expansion side port 11 formed of a leaf valve with a fixed inner circumference that bends toward the piston lower chamber 9 side. Side damping generation valve 13
Further, a check valve 14 that opens toward the piston upper chamber 8 side is provided at the upper mouth end of the pressure side port 12.

The piston rod 5 consists of a rod part to which the piston 4 is attached and a pipe part screwed to the rod part, and has a bypass oil passage 15 that communicates the piston upper chamber 8 with the reservoir chamber 7. There is a variable orifice on the expansion side that can be externally adjusted from the upper end of outer tube 1 (not shown).
is interposed.

Further, a hollow cylindrical oil lock piece 16 is attached to the lower end of the piston rod 5 with its base end screwed together.
An oil passage 17 that communicates between the lower piston chamber 9 and the inside of the oil lock piece 16 is formed at the base end of the piston 6, and a check valve 18 that opens into the oil lock piece 17 is provided at the inner end of this oil passage 17. It is provided.

Note that this check valve 18 has a check spring 1 interposed between it and a spring holder 20.
Due to the restoring force of 9, it is always biased in the closing direction.

A cap member 21 is inserted through the lower end of the inner tube 2, and the damper cylinder 3 is fixed to the lower bottom of the inner tube 2 by screwing the cap member 21 into the lower end of the damper cylinder 3.

The cap member 21 is attached to the support rod 2 at the upper end.
2, and a partition wall member 25, a spacer 29, etc. are attached to this support rod 22 with nuts 32 via washers 31.

The partition member 29 has a compression side port 26 and a growth side port 27. At the lower mouth end of the compression side port 26, a compression side damping force generating valve 24 consisting of a leaf valve with a fixed inner circumference that bends downward is provided. Furthermore, check valves 28 that open toward the piston lower chamber 9 are provided at the upper mouth ends of the extension ports 27, and these constitute the base valve 10.

From the spacer 29 to the support rod 22 and the cap member 21, a series of bypass oil passages 30, 3 communicate the lower piston chamber 9 to the reservoir chamber 7.
3 and 34 are bored, and the cap member 2
1, a needle valve 35 is inserted between the bypass oil passages 33 and 34 so as to be movable forward and backward.

The needle valve 35 can be externally adjusted from the lower end of the inner tube 2, and forms a pressure side variable orifice.

Further, an annular space is formed around the outer periphery of the spacer 29 by the spacer 29 and the washer 31, and within this annular space, the bottom part 23a of the hollow cylindrical oil lock case 23 can be moved laterally and tilted. They are engaged to maintain a floating state.

The oil lock case 23 has projections 37a and 37b spaced apart from each other on the outer periphery of the upper and lower parts, and these projections 37a and 37b prevent the oil lock piece 16 from floating excessively. By arranging the damper to face the damper, it is fitted into the oil lock case 23 near the maximum compression of the damper.

Thus, by connecting the upper part of the outer tube 1 to the body of a motorcycle or the like via a bracket (not shown) and supporting the front wheel with the acrylic bracket 6 attached to the lower part of the inner tube 2, an inverted damper is built in. Used as a front fork.

Next, the effect will be explained.

During compression operation of the front fork, the hydraulic oil in the piston lower chamber 9 is drained from the piston upper chamber 8 by opening the pressure side port check valve 14 of the piston 4.
send to.

At the same time, the hydraulic oil in the piston lower chamber 9 is pushed out from the bypass oil passages 30, 33, and 34 to the reservoir chamber 7 through the pressure side variable orifice and the oil hole 36, and in parallel with this, the intrusion volume of the piston rod 5 is An amount of hydraulic oil corresponding to the amount of water is pushed out from the pressure side port 26 of the partition member 25 to the reservoir chamber 7 through the oil hole 36 while pushing open the pressure side damping force generating valve 24, and at this time, the hydraulic oil flows through the pressure side variable orifice. The compression damping force is generated by the resistance and the flow resistance of the hydraulic oil flowing while pushing the compression damping force generating valve 24 open.

During the above compression operation, when the front fork reaches near the maximum compression, the oil lock piece 16 in the damper begins to fit into the oil lock case 23 below. In this case, even if there is eccentricity between the oil lock piece 16 and the oil lock case 23, the oil lock case 23 in the floating state will fit into the oil lock piece 16 while being self-centering, and Internal hydraulic oil is pushed out through the gap between the outer circumferential surface of the lock piece 16 and the inner circumferential surface of the oil lock case 23, and a cushioning action is performed by the flow resistance of the hydraulic oil passing through the gap.

On the other hand, when the front fork is extended, the hydraulic oil in the piston upper chamber 8 is pushed out from the bypass oil passage 15 through the extension side variable orifice to the reservoir chamber 7, and in parallel, the oil is pushed out to the extension side port of the piston 4. 11 to rebound damping force generation valve 1
3 into the lower piston chamber 9 while pushing it open,
At this time, a rebound damping force is generated by the flow resistance of the hydraulic oil passing through the rebound variable orifice and the flow resistance of the hydraulic oil flowing while pushing open the rebound damping force generating valve 13.

At the same time, an amount of hydraulic oil corresponding to the withdrawal volume of the piston rod 5 is pumped from the reservoir chamber 7.
The oil is sucked into the piston lower chamber 9 from the oil hole 36 through the expansion side port 27 of the partition member 25 while opening the check valve 28.

When the front fork is extended from the vicinity of its maximum compression, the oil lock piece 16 and oil lock case 23, which are engaged with each other, operate in the direction of coming out in addition to the above-mentioned damping action. The inside tries to become negative pressure. Therefore, the check valve 18 opens and the hydraulic oil in the piston lower chamber 9 is removed from the oil lock piece 16.
and into the oil lock case 23 to eliminate the negative pressure phenomenon and prevent abnormal noise generated when the oil lock piece 16 and the oil lock case 23 are separated.

In addition, at this time, since the check valve 18 for suctioning hydraulic oil is provided at the base end of the oil lock piece 16 on the piston rod 5 side, the piston 4 is removed from the piston upper chamber 8 of the damper cylinder 3.
A part of the hydraulic oil that has been pushed out into the piston lower chamber 9 through the rebound damping force generating valve 13 is sucked into the oil lock piece 16 and the oil lock case 23 through the check valve 18.

In this case, the hydraulic oil pushed out from the piston upper chamber 8 is compressed in the piston upper chamber 8 and is pushed out into the piston lower chamber 9 in the form of gas separation, and this hydraulic oil containing almost no gas is The oil is sucked into the oil lock piece 16 and the oil lock case 23, and therefore the oil lock piece 16 and the oil lock case 23 are
The gas in the hydraulic oil will precipitate inside the damper, and this gas will no longer enter the damper and disturb the damping force.

<Effects of the invention> As described above, according to this invention, even if there is eccentricity between the oil lock case and the oil lock piece, the oil lock case can be moved relative to the oil lock piece near the maximum compression of the front fork. The two fit smoothly while self-aligning, and the internal hydraulic oil is pushed out from the gap between the inner circumferential surface of the oil lock case and the outer circumferential surface of the oil lock piece.
The flow resistance of the hydraulic oil through the gap makes it possible to always exert a stable cushioning action without adversely affecting the damping action of the damper itself.

In addition, a check valve for suctioning hydraulic oil is provided at the base end of the oil lock piece attached to the piston rod side, so when the oil lock case and oil lock piece are extended apart from each other, the piston is removed from the piston upper chamber of the damper cylinder. A part of the hydraulic oil that has been pushed out to the lower chamber of the piston through the rebound damping force generation valve is sucked into the oil lock case and oil lock piece through the check valve, and is also pushed out of the upper chamber of the piston. The hydraulic oil that comes is compressed in the upper chamber of the piston to separate gases and is in a form that contains almost no gas, so that almost no gas is separated from the hydraulic oil inside the oil lock case and oil lock piece. Therefore, it is also possible to eliminate the problem of gas entering the damper and disturbing the damping force.

[Brief explanation of drawings]

FIG. 1 is a partial vertical sectional front view of a front fork equipped with a cushion device according to an embodiment of the invention, FIG. 2 is a vertical sectional front view showing an enlarged portion of the cushion device, and FIG. FIG. 3 is a top cross-sectional plan view of the oil lock case. 1... Outer tube, 2... Inner tube, 3... Damper cylinder, 4... Piston, 5... Piston rod, 16... Oil lock piece, 18... Check valve, 23... Oil lock case.

Claims (1)

[Scope of utility model registration request] The inner tube is slidably inserted into the outer tube, and the damper cylinder is positioned inside the inner tube and stands up from the center of the bottom, while the tip of the piston rod extending outward from the damper cylinder is inserted into the upper end of the outer tube. In an inverted type front fork with built-in damper connected to The lock case is connected to the damper cylinder so as to be movable laterally and tiltably while maintaining a floating state, and a check valve is provided at the base end of the oil lock piece and opens into the oil lock piece. A front fork cushioning device featuring: