JPH049462Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a front fork that is interposed between the front body of a motorcycle and an axle, and serves as a fork and a shock absorber for damping vibrations from the road surface.

[Conventional technology]

In general, a motorcycle has a front fork interposed between the front body and the axle, which also serves as a fork and a shock absorber. As this front fork, for example, a front fork with a built-in damper as shown in FIG. 3 has been developed. (Utility Application No. 61-145697) In this front fork, an inner tube 3 is slidably inserted into an outer tube 1 via a bearing 2, and a damper cylinder 4 stands up at the bottom of the outer tube 1. 4 includes a piston rod 6 via a piston 5.
is movably inserted, and the piston 5 defines two upper and lower oil chambers 22 and 23 within the damper cylinder 4.

The piston 5 is provided with a passage 31 through which the oil chambers 22 and 23 communicate, and an expansion-side damping force generating mechanism 24 is built in the passage 31.

The housing 8, which is screwed onto the piston rod 6 and has the piston 5 attached thereto, is formed with passages 33 and 34 that communicate the two oil chambers 22 and 23, and a damping force generator including a needle valve 35 in the middle of these passages 33 and 34. A mechanism 25 is provided.

A small hole 30 opening into the upper oil chamber 22 is bored in the damper cylinder 4, and this small hole 30 allows air mixed in the damper cylinder to be discharged to the oil chamber 10 in the outer tube 1. The small hole 30 can also be used as an orifice for generating an extension-side damping force by allowing the oil in the upper oil chamber 22 to flow out into the external oil chamber 10 during the extension operation.

[Problem that the invention attempts to solve]

In a front fork with a built-in damper, air may get mixed into the damper when the damper is assembled, and if this air gets mixed in, the desired damping force cannot be obtained. For this reason, in the above-mentioned front fork, a small hole 30 is formed in the damper cylinder 4 to vent air, but on the contrary, this small hole 30 has an adverse effect during compression operation, and the outside of the damper cylinder 4, in other words, the oil There is a possibility that the oil in the chamber 10 or the air mixed in the oil and the oil may be sucked in.

Therefore, an object of the present invention is to provide a front fork that can reliably discharge air mixed in the damper and prevent external oil and air from being sucked in.

[Means for solving problems]

In order to achieve the above purpose, the configuration of the present invention is as follows:
An outer tube and an inner tube are slidably fitted, a damper cylinder is erected at the bottom of one of the tubes, a piston rod is movably inserted into the damper cylinder via a piston, and the piston is inserted into the damper cylinder. The cylinder is divided into two oil chambers, upper and lower, and the two oil chambers are connected via a damping force generation mechanism installed in the piston.In the front fork, a passage is provided that allows the piston rod to communicate with the two oil chambers. , a valve is provided in the middle of this passage so that it can be opened and closed; the valve is provided with an air passage that connects with the passage; and a check valve that is opened and opened by extension operation is provided in the air passage so that it can be opened and closed. This is a characteristic feature.

[Effect]

When the piston expands and contracts, oil flows through the passage inside the piston rod that is restricted by a valve, generating damping force. During the extension operation, the internal pressure in the upper oil chamber opens the check valve, and the air mixed in the upper oil chamber is discharged through the air passage to a chamber inside the control rod outside the damper cylinder.

During compression, the check valve is pushed by the internal pressure in the lower oil chamber to close the air passage and prevent the oil in the lower oil chamber from flowing into the chamber from the air passage.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2.

The embodiments shown in FIGS. 1 and 2 include a piston rod,
Although the passage formed in the piston rod and the valve mechanism are shown, the other structure and operation of the front fork are the same as in FIG. However, the small hole 30 shown in FIG. 3 is not formed.

First, the embodiment shown in FIG. 1 will be described.

A piston rod 6 is movably inserted into the damper cylinder 4 via a piston 3, and the piston 3 is inserted into the damper cylinder 4 into two upper and lower oil chambers 2.
2 and 23, and the piston 3 is provided with an extension side damping force generation mechanism that allows the two oil chambers 22 and 23 to communicate with each other.

A valve housing 8 is screwed into the lower part of the piston rod 6, and this valve housing 8 has a vertical passage 9 through which upper and lower oil chambers 22 and 23 communicate.
A lateral passage 11 is formed.

The valve housing 8 forms part of the piston rod 6, and the two may be molded in one piece.

The piston rod 6 is formed hollow, and a needle valve 7 and a hollow control rod 12 are inserted in series in the piston rod 6 so as to be movable up and down.
is formed, and a chamber 15 is provided within the control rod 12.

One air passage 14 opens into the passage 11 , and the other air passage 13 opens into the chamber 15 .

Step part of valve housing 8 and needle valve 7
A return spring 16 is interposed between the stepped portions to constantly urge the needle valve 7 upward.

The control rod 12 is operated from the outside to move up and down to set the needle valve 7 to an arbitrary position.

A hollow valve seat 17 is provided in the middle of the passage 9, the valve head 7a of the needle valve 7 faces this valve seat 17, and the gap between the valve head 7a and the valve seat 17 can be adjusted as desired by the control rod 12. The damping force can be adjusted externally.

A check valve 18 having a T-shaped cross section and a flange 18b is inserted into the hole 19 at the center of the lower part of the needle valve 7 so as to be movable up and down. 13 to open and close.

In the middle of the passage 9, there is a stopper 21 made of a pin etc.
is provided, and even when the check valve 18 is lowered again, the check valve 18 is stopped by this stopper 21.
prevents it from slipping out.

During the extension operation, the piston 3 rises, and part of the oil in the upper oil chamber 22 flows out into the lower oil chamber 23 via the damping force generation mechanism of the piston 3, and at the same time, another part of the oil flows from the passage 11 to the needle valve. The lower oil chamber 23 is connected to the passage 9 through the outer peripheral gap in the valve head 7a of No. 7.
The flow resistance of the outer circumferential gap generates an elongation damping force.

When oil flows through the passage 9, hydraulic pressure acts on the lower flange 18b of the check valve 18, pushing the check valve 18 down. For this reason, check valve 18
The upper base end opens an air passage 13, oil flowing from the passage 11 flows into the air passages 14 and 13, and air mixed in this oil is discharged into the chamber 15.

On the other hand, during compression, a part of the oil in the lower oil chamber 23 flows out into the upper oil chamber 22 via the passage 9, the gap around the outer periphery of the valve head 7a, and the passage 11, and the oil corresponding to the volume of the piston rod intrusion flows downward into the damper cylinder 4. The reservoir, i.e., the third
It flows out into the oil chamber 10 shown in the figure.

When oil flows through the gap around the outer circumference of the valve head 7a, a pressure-side damping force is generated, and the hydraulic pressure in the passage 9 causes the check valve 1 to
8 is pushed up, and the upper base end of the check valve 18 closes the air passage 13. For this reason, passage 9,1
1, when oil flows, this oil flows through air passage 13 and chamber 1.
5 will not leak. Therefore, it does not adversely affect the compression damping force.

FIG. 4 shows another embodiment of the present invention, in which the valve and check valve are modified, and the other structures, functions and effects are the same as the embodiment of FIG. 3.

The valve head 7a of the needle valve 7 is provided in the middle of the passage 9 and faces a stepped portion 17a, which is a valve seat, and generates an expansion/compression damping force in the gap between the valve head 7a and the stepped portion 17a.

A spacer 20 is inserted into the center of the needle valve 7, and an air passage 13 is formed within this spacer 20.

A hole 19a that opens into the passage 9 is formed in the lower part of the needle valve 7, and a check valve 18a is inserted into the hole 19a so as to be able to move up and down, and the upper valve head of the check valve 18a opens and closes on the lower seat of the spacer 20. It touches freely.

A shoulder portion serving as a pressure receiving surface is formed on the left side of the check valve 18a.

During the extension operation, a portion of the oil in the upper oil chamber 22 flows out into the lower oil chamber 23 via the passage 11, the outer peripheral gap of the valve head 7a, and the passage 9. At this time, the oil introduced into the air passage 14 acts on the pressure receiving surface of the check valve 18a, lowering it and opening the air passage 13. Therefore, air mixed in the oil introduced into the air passages 14 and 13 can be discharged into the chamber 15.

During compression operation, a portion of the oil in the lower oil chamber 23 flows out from the passage 9, the outer peripheral gap of the valve head 7a, and the passage 11 into the upper oil chamber 22. At this time, the oil pressure in the passage 9 is
A acts on the check valve 18a and pushes it up, acts on the check valve 18a and pushes it up, and closes the air passage 13. Therefore, oil in the passage 11 is prevented from flowing into the air passage 13 and the chamber 15.

[Effect of idea]

According to the present invention, the following effects can be obtained.

1. Since a valve is provided in the passage of the piston rod so that it can be opened and closed, an expansion/compression damping force is generated depending on the opening degree of the valve.

2. An air passage is provided in the needle valve, and a check valve is installed in this air passage so that it can be opened and closed freely.When the needle valve is extended, the check valve opens and the air mixed in the upper oil chamber can be discharged to the air passage side. . Therefore, during assembly, air mixed in the damper can be discharged, and variations in damping force can be prevented.

3. The check valve closes during compression operation and does not suck in air or excess oil, so it does not have any negative effects during compression operation.

[Brief explanation of the drawing]

1 and 2 are partially cutaway longitudinal sectional front views of a damper portion of a front fork according to an embodiment of the present invention, and FIG. 3 is a partially cutaway longitudinal sectional front view of a conventional front fork. Explanation of symbols, 1... Outer tube, 2...
Inner tube, 3... Piston, 4... Damper cylinder, 6... Piston rod, 7... Valve, 9, 11... Passage, 13, 14... Air passage, 18, 18a... Check valve, 22, 2
3... Oil chamber, 24, 25... Damping force generation mechanism.

Claims (1)

[Claims for Utility Model Registration] (1) An outer tube and an inner tube are slidably fitted, a damper cylinder is erected at the bottom of one of the tubes, and a piston is inserted into the damper cylinder. The piston rod is movably inserted, and the piston divides the damper cylinder into two upper and lower oil chambers. A passage is provided to communicate the two oil chambers, upper and lower, and a valve is provided in the middle of this passage so that it can be opened and closed freely.The valve is provided with an air passage that connects to the passage, and there is a check in the air passage that opens the valve when it is extended. Front fork with a valve that can be opened and closed. (2) The front fork according to claim 1, wherein the air passage is open to a chamber in a hollow control rod that controls the valve. (3) The front fork according to claim 1, wherein the valve is a needle valve. (4) The front fork according to claim 1, wherein the check valve is opened by the internal pressure of the upper oil chamber when extended and closed by the internal pressure of the lower oil chamber when compressed.