JPH04312221A - Front fork - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork that is interposed between the body and axle of a motorcycle and serves as both a shock absorber and a fork to damp vibrations from the road surface.

0002

[Prior Art] Generally, in a front fork of a motorcycle, a wheel side tube is slidably inserted into a vehicle body side tube, and a reservoir consisting of a gas chamber and an oil chamber is provided in the vehicle body side tube and the wheel side tube. ing.

In particular, in order to improve the sliding property between the vehicle body side tube and the wheel side tube, for example,
As in the front fork shown in Publication No. 2, an oil chamber for lubrication is divided between the vehicle body side tube and the wheel side tube via two upper and lower bearings, and a communication hole is formed between this oil chamber and the reservoir side oil chamber. A communication system has been developed that communicates through

0004

Problem to be Solved by the Invention The oil level of the oil chamber for lubrication is equal to the oil level height of the reservoir side oil chamber because this oil chamber itself directly communicates with the reservoir side oil chamber. For this reason, when the oil level in the lubrication oil chamber is in contact with the upper bearing, good lubrication can be achieved, but when the oil level in the reservoir side oil chamber drops during extension operation, the oil level in the lubrication oil chamber decreases. As the distance between the upper bearing and this oil level increases, the lubrication function decreases.

In this case, the upper bearing is somewhat lubricated by oil splashed from the oil chamber for lubrication and the oil chamber on the reservoir side during the expansion and contraction operation, but the formation of an oil film on the sliding surface is insufficient.
There is a problem that sliding properties are poor.

Therefore, an object of the present invention is to provide a front fork that improves the lubrication function by always bringing the oil in the oil chamber for lubrication into contact with or close to the bearing, regardless of the oil level height in the reservoir side oil chamber during expansion and contraction. The goal is to provide the following.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the structure of the present invention is such that an oil chamber for lubrication is partitioned between a vehicle body side tube and a wheel side tube via two upper and lower bearings, This oil chamber for lubrication has an oil hole provided in the wheel side tube,
This oil hole is characterized in that it communicates with the reservoir side oil chamber via a check valve provided in the middle of the oil hole so as to be openable and closable.

[0008]

[Effect] During compression, the pressure in the oil chamber on the reservoir side increases,
A differential pressure is generated between the pressure in the expanding oil chamber for lubrication and the oil in the oil chamber on the reservoir side opens the check valve and is introduced into the oil chamber for lubrication, and when the check valve is extended from this state, the check valve closes. This check valve prevents the oil in the lubrication oil chamber from flowing out to the reservoir side even if the oil level in the reservoir side oil chamber drops. Therefore, the upper bearing is constantly immersed in oil while continuing the pumping action.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIGS. 1 and 2 show an embodiment of the present invention.

A wheel side tube 2 connected to the wheel side is slidably inserted into a car body side tube 1 connected to the car body side, a bottom is provided at the end of the wheel side tube 2, and a bottom is provided at the end of the wheel side tube 2. The damper cylinder 15 is erected, and the piston rod 3 is movably inserted into the damper cylinder 15 via a piston, and the vehicle body side tube 1 and the piston rod 3 are interlocked via a cap 4.

The wheel side tube 2 is a damper cylinder 15
It is constantly biased in the direction of extension via a suspension spring 5 and a seat 6 provided between the cylindrical head 7 at the upper end and the cap 4.

A bearing 8, a seal 12, and a dust seal 13 are provided on the lower inner periphery of the vehicle body side tube 1, and a bearing 9 is provided on the upper outer periphery of the wheel side tube 2.
The wheel side tube 2 is sliding through it.

An oil chamber 10 for lubrication is defined between the wheel side tube 2 and the vehicle body side tube 1 by the bearings 8 and 9.
The inside of the wheel-side tube 2 is divided into an oil chamber 11 serving as a reservoir and a gas chamber 11a.

[0015] The wheel side tube 2 is also arranged such that it is located between the oil level A of the oil chamber 11 of the reservoir when the damper is fully extended and the bearing 8 provided on the inner periphery of the lower part of the vehicle body side tube 1. An oil hole 14 is provided, and the oil chamber 10 for lubricating oil and the oil chamber 11 of the reservoir communicate with each other through the oil hole 14 .

A through hole 16 is formed in the head 7 of the damper cylinder 15 to allow oil in the oil chamber 11 of the reservoir to flow vertically.

An upper seal 18 and a lower check valve 17 are provided on the outer periphery of the head 7.
A passage between the check valve 8 and the check valve 17 faces the oil hole 14.

During compression, the vehicle body tube 1 and the piston rod 3 descend, and the oil corresponding to the volume of the piston rod 3 entering the damper cylinder 15 is discharged from the damper cylinder 15 into the oil chamber 11 of the reservoir. The inside of the reservoir is pressurized and the oil rises. At this time, the vehicle body side tube 1
As the lubrication oil chamber 10 is lowered, the oil chamber 10 for lubrication expands, and a pressure difference is generated between the oil chamber 11 in the reservoir and this oil chamber 10 for lubrication. portion pushes open the check valve 17 and is introduced into the oil chamber 10 for lubrication via the through hole and the oil hole 14.

Oil is introduced into the oil chamber 10 for lubrication until the pressure of the gaseous air in the oil chamber 10 is balanced with the pressure in the reservoir.

When this state shifts to the extension operation, the vehicle body side tube 1 rises and the oil chamber 10 for lubrication is compressed, but the internal pressure at this time pushes the check valve 17 in the closing direction and the through hole closes. Since the oil hole 14 and the oil hole 14 are closed to the reservoir side, the oil in the oil chamber 10 for lubrication is prevented from flowing out from the oil hole 14, and a pumping operation is performed on the oil chamber 10 for lubrication during a so-called expansion and contraction operation. .

This pumping operation continues until the air in the oil chamber 10 for lubrication is exhausted through a small gap in the upper bearing 9, and continues thereafter to maintain the oil level.

Furthermore, even if the extension operation is performed while the oil chamber 10 for lubrication is filled with oil, this oil will be discharged upward through the slight gap between the upper bearing 9 and the vehicle body side tube 1. Since oil remains around the bearing 9, the lubrication effect is improved.

Even if the oil level A in the oil chamber 11 on the reservoir side falls during the extension operation, the oil in the oil chamber 10 for lubrication is blocked by the check valve 17 and is not discharged, so that the upper and lower bearings 8,
9 is always immersed in oil to maintain oil lubrication.

The bearings 8 and 9 may be provided on either the vehicle body side tube 1 or the wheel side tube 2.

FIG. 3 shows another embodiment of the invention.

In this case, a disk 19 and a valve body 20 are assembled in the head 7, a through hole 23 is provided in the disk 19, a pressure port 21 and an extension port 22 are provided in the valve body 20, and an upper outlet end of the pressure port 21 is provided. Pressure side leaf valve 2
5 is provided so as to be freely openable and closable, and a check valve 24 is provided at the lower outlet end of the extension port 22 so as to be freely openable and closable.

The other structures are the same as those of the embodiment shown in FIG. 1, and are given the same reference numerals.

In the case of this embodiment, even if the pressure difference between the pressure inside the reservoir and the oil chamber 10 for lubrication is small, the pressure is increased by the leaf valve 25 etc. during compression operation, and the check valve 17 is opened for lubrication. The pumping operation for introducing oil into the oil chamber 10 can be performed reliably.

Other functions and effects are the same as those of the embodiment shown in FIG.

The check valve 17 that opens and closes the oil hole 14 is not limited to the one shown in the figure; for example, the check valve 17 that opens and closes the oil hole 14 is
It may be provided midway inside the oil hole 14 or midway on the inlet side or outlet side of the oil hole 14.

[0031]

[Effects of the Invention] According to the present invention, since the oil chamber for lubrication is opened and closed on the reservoir side via the check valve, the check valve is opened during compression and oil is introduced, and oil is prevented from being discharged during expansion. Therefore, this oil chamber for lubrication is filled with oil regardless of the oil level level on the reservoir side, and in particular, the upper bearing is always in contact with or close to the lubricating oil, which improves the expansion and contraction operation due to lubrication. .

[Brief explanation of drawings]

FIG. 1 is a partially vertical 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;

FIG. 3 is a partially enlarged sectional view of a front fork according to another embodiment of the present invention.

[Explanation of symbols]

1　Vehicle side tube 2 Wheel side tube 8,9 Bearing 10 Oil chamber for lubrication 11 Reservoir side oil chamber 14 Oil hole 17 Check valve

Claims (1)

[Claims] [Claim 1] A front fork in which a wheel side tube is slidably inserted into a vehicle body side tube, and a reservoir consisting of a gas chamber and an oil chamber is provided in the vehicle body side tube and the wheel side tube. A lubrication oil chamber is defined between the tube and the wheel side tube via two upper and lower bearings, and this lubrication oil chamber can be opened and closed between the oil hole provided in the wheel side tube and in the middle of this oil hole. A front fork characterized by communicating with a reservoir side oil chamber via a check valve provided in the front fork.