JPH02212286A - Inverted type front fork - Google Patents

Abstract

PURPOSE:To enhance the shock absorbing characteristic by furnishing an orifice to put an oil chamber below a piston in communication with an oil sump chamber, furnishing also another orifice to put the two oil chambers above and below the piston in communication with each other, and thereby generating a damping force both in expansion and contraction simply and certainly. CONSTITUTION:An inner tube 2 supported on the axle side is slidably inserted in the inside of an outer tube 1, which is supported on the car body side. A piston 3 in slide contact with the inside of this inner tube 2 is supported by the base end of the outer tube 1 through a hollow piston rod 4. An orifice 12, which puts an oil chamber 8 above the inner tube 2 in communication with an oil sump chamber 10, and a check valve 13 to open only to the elongation side are installed inside of the hollow part of the piston rod 4. Another orifice 14 to put the upper and lower oil chambers 8, 9 in communication with each other is provided at the wall surface of the piston rod 4. This enables simple and sure generation of damping force both in elongation and contraction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a damping force generating means in an inverted front fork in which an outer tube is disposed on the vehicle body side and an inner tube is disposed on the wheel side.

(Prior Art) A 70-ton fork for a two-wheeled vehicle in which an outer tube is disposed on the vehicle body side and an inner tube is disposed on the axle side is known, for example, as disclosed in Japanese Patent Application Laid-open No. 85777/1983.

As shown in FIG. 4, an inner tube 2 is slidably housed in an outer tube 1, and a piston 3 that is in sliding contact with the inside of the inner tube 2 is connected to the outer tube 1 via a hollow piston rod 4. A bearing 5 that slides on the outside of the piston rod 4 is provided at the upper end of the inner tube 2 .

An oil reservoir chamber 10 in which gas is sealed above the oil level is formed inside the upper part of the outer tube 1 and the piston rod 4, and these chambers communicate with each other via a boat 11.

Further, the piston rod 4 has an orifice 14 that communicates the oil chamber 8 above the piston 3 in the inner tube 2 with the oil reservoir chamber 10, and the bearing 5 has a check valve (not shown) that opens when the pressure side is operated. Also provided are orifices (not shown) and check valves that open during pressure side operation.

In the pressure side operation, the hydraulic oil in the oil chamber 9 below the piston 3 flows into the oil chamber 8 above via the check valve provided in the piston 3, and the hydraulic oil corresponding to the intrusion volume of the piston rod 4 flows into the piston rod 4. Oil sump chamber 1 through the hollow part of 4.
Flows into 0. In addition, in the expansion side operation, the oil reservoir chamber 10
The hydraulic oil passes through the hollow part of the piston rod 4 and returns to the oil chamber 9, and the hydraulic oil in the oil chamber 8 passes through the orifice 14 and the orifice formed in the piston 3, generating a damping force. flows into.

(Problem to be solved by the invention) However, in this 70-ton, 7-year-old child, the generation of damping force is limited to the expansion side operation, and the structure is such that no damping force can be generated during the compression side operation.

In view of the above problems, the present invention can generate both expansion and compression damping forces with a simple structure. The purpose of the present invention is to provide an inverted front 7t.

(Means for Achieving the Object) The present invention includes an inner tube supported by an axle that is slidably inserted into an outer tube supported by a vehicle body, and a piston that slides in contact with the inside of the inner tube is replaced by a hollow piston. In an inverted front fork that is supported on a seven-way tube via a rod, an orifice is provided in the hollow part of the piston rod that communicates the oil chamber below the piston of the inner tube with the oil reservoir chamber formed at the top of the outer tube.
Another orifice that communicates the oil chamber above the piston of the inner tube with the oil chamber below is formed on the wall surface of the piston rod below the orifice.

(Function) During pressure side operation, the orifice 7 provided in the hollow part of the piston rod
The 4th foot resists the flow of hydraulic oil from the oil chamber below the piston to the oil reservoir chamber and generates a damping force, and during the rebound operation, the 4th foot formed on the wall of the piston rod moves the oil from the oil chamber above the piston to the piston. It generates damping force by resisting the flow of hydraulic oil into the oil chamber below.

(Example) Embodiments of the present invention are shown in FIGS. 1 to 3.

In FIG. 1, 1 is an outer tube supported on the vehicle body side, and 2 is an inner tube supported on the axle side. The inner tube 2 is slidably inserted inside the outer tube 1, and a piston 3 that is in sliding contact with the inside of the inner tube 2 is inserted into the outer tube 1 via a hollow piston rod 4.
is supported at the proximal end of the

A bearing 5 is provided at the upper end of the inner tube 2 and slides on the outer periphery of the piston rod 4, and a main spring 6 is interposed between the piston 3 and the bottom of the inner tube 2.
and the sub-spring 7 inserted between the bearing 5 and the bearing 5.
It is elastically supported inside the inner tube 2 by.

The inside of the inner tube 2 is defined by the piston 3 into an upper oil chamber 8 and a lower oil chamber 9. Further, an oil reservoir chamber 10 is formed in the upper part of the hollow portion of the outer tube 1 and the piston rod 4 in which a bus is enclosed above the oil surface. Note that the inside and outside of the piston rod 4 communicate with each other via a boat 11 formed at the top of the piston rod 4.

The lower end of the hollow portion of the piston rod 4 opens toward the oil chamber 9, and inside this hollow portion there is an orifice 12 that communicates the oil chamber 9 and the oil reservoir chamber 10, and a check valve 1 that opens only when the piston rod is operated on the extension side.
3 is provided.

In addition, an oil chamber 8 is provided on the wall surface of the piston rod 4 below these.
An orifice 14 is formed that communicates with and 9.

Next, the effect will be explained.

During pressure side operation, as the piston 3 slides downward inside the inner tube 2, the hydraulic oil in the oil chamber 9, which is contracting as shown in FIG. 2, flows into the oil chamber 8, which is expanding, via the orifice 14. At the same time, the hydraulic oil corresponding to the intrusion volume of the piston rod 4 flows out into the oil reservoir chamber 10 through the orifice 12 while generating a pressure side reduction force.

In addition, when operating on the extension side, the oil reservoir chamber 10
The hydraulic oil that had flowed out to the oil chamber 9 returns to the expanding oil chamber 9 via the check valve 13 without resistance, and the oil chamber 8 contracts.
The hydraulic oil flows into the oil chamber 9 through the orifice 14 while generating a damping force.

In this way, by generating a damping force when operating in either the compression side or the expansion side, shocks and vibrations applied to the front wheels are efficiently damped, making it possible to drive comfortably.

Note that, depending on the flow rate balance 1 between the orifices 12 and 14, the check valve 13 may be omitted.

(Effects of the Invention) As described above, the present invention provides an orifice in the hollow portion of the piston rod that communicates the oil chamber below the piston with the oil reservoir chamber, and connects the oil chamber above the piston with the oil chamber below. Another communicating orifice is formed on the wall surface of the piston rod below the OIJ ice, so the orifice in the hollow part generates damping force during compression side operation, and the orifice on the piston rod wall surface generates damping force during rebound side operation, making it easy to use. The structure provides damping force in both the expansion and compression directions, improving the damping characteristics of the inverted front fork.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main part of an inverted front 7t-ri showing an embodiment of the present invention, and FIG. 2 and FIG. 3 are further enlarged cross-sectional views of the main part of FIG. Further, FIG. 4 is a longitudinal cross-sectional view of an inverted type 70-7t truck showing a conventional example. 1... Outer tube, 2... Inner tube, 3
...Piston, 4...Piston lower)', 8,9・
...Oil chamber, 10...Oil sump room, 12.14-0. Orifice.

Claims (1)

[Claims] In an inverted front fork, an inner tube supported by the axle is slidably inserted into an outer tube supported by the vehicle body, and a piston that slides in contact with the inside of the inner tube is supported by the outer tube via a hollow piston rod. An orifice is provided in the hollow part of the piston rod that communicates the oil chamber of the piston lower blade of the inner tube with the oil reservoir chamber formed at the upper part of the outer tube, while the oil chamber above the piston of the inner tube and the oil chamber below the piston are connected. An inverted front fork, characterized in that another orifice communicating with the piston rod is formed on the wall surface of the piston rod below the orifice.