JPS606389Y2 - front fork - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an improvement of a front fork for a two-wheeled vehicle.

As a conventional general front fork, for example, the first
There is something like the one shown in the figure.

To explain this, 1 is an outer tube, 2 is a piston rod, and 3 is a piston, and the piston 3 divides the inside of the outer tube 1 into an upper chamber 4 and a lower chamber 5.
The upper chamber 4 communicates with a lower chamber 5 through an orifice 6 provided in the piston 3.

When the front fork operates on the pressure side, the lower chamber 5 is compressed by the lowering of the piston 3, so hydraulic oil flows from the lower chamber 5 to the upper chamber 4 through a check valve (not shown) of the piston 3.

At this time, as the penetrating volume of the piston rod 2 increases, the oil level in the upper chamber 4 relatively rises, and the air chamber 7 above the upper chamber 4 contracts.

On the other hand, when the front fork is operated on the extension side, oil flows from the upper chamber 4 through the lower chamber 5 and the orifice 6 due to the rise of the piston, exerting a predetermined damping effect. 4 is relatively lowered and the air chamber 7 is enlarged.

In other words, with the expansion and contraction of the front fork,
The oil level in the upper chamber 4 suddenly moves up and down, resulting in the oil blowing up into the air chamber 7 and causing aeration in which air is drawn into the oil, resulting in inconveniences such as deterioration of operating performance.

In order to solve the above problems, the present applicant has already filed an application for a front fork as shown in FIG.

To explain this, the inner tube 11 is slidably inserted into the outer tube 12, and the outer tube 12 is inserted into the outer tube 12.
The inner tube 11 is supported by two bearing parts 13 and 14 provided axially apart from each other, and these bearing parts 1
3.14, an annular piston 15 is provided on the outer periphery of the inner tube 11, and the inner tube 2--B l
The inside of the annular chamber formed by the outer periphery of the inner tube 12, the inner periphery of the outer inner 12, and the two bearing parts 13.14 is divided into an oil chamber A and an oil chamber B by the piston 15, and The oil sump chamber C and the oil chambers A and B are communicated through orifices 16.17, etc., and the oil chamber A expands and contracts via the orifices 16.17 as the inner tube 11 slides.
It is configured to allow hydraulic oil to flow in and out of B to exert a predetermined damping force.

In this case, the total volume of oil chambers A and B is inner tube 1
Since it remains unchanged regardless of the position of 1, it is possible to prevent the oil level from changing in the oil reservoir chamber C due to the expansion and contraction operation of the front fork.

Furthermore, by providing the axle support part 20 on the outer tube 12 so that the axle 19 is located between the bearing parts 13 and 14, the sliding movement is improved compared to the conventional front fork, regardless of the extension/retraction position of the inner tube 11. This is designed to reduce dynamic friction and provide stable characteristics.

However, in such a front fork, since the inner tube 11 is supported by two bearings 13 and 14, the lower part 11a of the inner tube 11 is connected to the outer tube 1 when the front fork is operated on the pressure side.
It protrudes from the lower end of 2.

Due to this protrusion of the inner tube 11 in the direction of the ground contact surface, the exposed surface of the inner tube 11 may be damaged by flying stones, dust, muddy water, etc. thrown up by the wheels, resulting in a gap between the inner tube 11 and the outer tube 12. There was a risk that smooth sliding would be impaired and operating performance would deteriorate.

Further, in order to secure a predetermined amount of hydraulic oil in the oil reservoir chamber C, the total length of the inner tube 11 becomes long, which may cause installation problems.

The purpose of this invention is to provide a front fork that solves the above problems by forming an oil reservoir chamber at the lower end of the outer tube that also serves as a protective cover for covering the inner tube.

This invention will be explained below based on the drawings.

FIG. 3 is a diagram showing an embodiment of this invention.

However, parts that are substantially the same as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in the figure, when the front fork operates on the pressure side, the inner tube 11 protrudes from the lower end of the outer tube 12, and a bottomed cylindrical protective cover 41 that surrounds the protruding inner tube 11 is connected to the lower end of the outer tube 12. ing.

The protective cover 41 mainly protects the inner tube 11 from flying stones, dust, etc., and its interior serves as an oil reservoir chamber C' communicating with an oil reservoir chamber C formed within the inner tube 11.

Therefore, the lower end of the inner tube 11 is open, and an annular projection 43 provided inside the mouth of the protective cover 41
is fitted into a groove provided in the outer circumferential wall of the lower end portion 42 of the outer tube 12 via an adhesive or the like, and is further tightened with a ring-shaped spring strip 44 to ensure complete oil tightness.

The hollow chamber 27 above the oil surface of the oil reservoir chamber C inside the inner tube 11 is filled with pressure gas that operates a gas spring 38 that presses the oil surface, and the pressure gas is filled and sealed. A containment valve 37 is provided in a cap 36 provided at the upper end of the inner tube 11.

Furthermore, a coiled suspension spring 29 is interposed between the inner tube 11 and the outer tube 12 in order to absorb the impact when the front fork is compressed.

That is, the suspension spring 29
The flange-shaped spring receiver of the cylindrical spring guide 30 that is in contact with the upper end surface of the inner tube 2 and is slidably attached to the outer circumferential surface of the inner tube 11 is connected to the inner tube 1 .
The inner tube 11 is interposed between the inner tube 11 and a spring stopper (not shown) fixed to the upper part of the inner tube 11, and urges the inner tube 11 toward the expansion side.

By the way, the volumes of the oil chambers A and B increase or decrease due to the movement of the piston 15 due to the expansion and contraction operation of the front fork, but the changes in volume are inversely proportional.

That is, when the oil chamber A expands in the axial direction, the volume of the oil chamber B decreases by the same amount as the volume increase.

Furthermore, when the pressure side is operated, the inner tube 11 enters into the protective cover 41, and the oil level rises by an amount corresponding to the volume of entry.As a result, the hollow chamber 27 contracts and the pressure gas and air are Rise.

In this way, the pressurized gas constantly presses the oil level, urges the outer tube 12 downward through the hydraulic oil and the protective cover 41, and the gas spring 38 acts to absorb shock when the front fork is compressed. do.

In the above configuration, the diagram shows the inner tube 11 moving to the maximum extension side, but when a load is actually applied, the gas spring 38 and the compression side spring (suspension spring) 29 The inner tube 11 moves relatively downward while being bent until it is balanced.

When the outer tube 1 is pushed up from the road surface from its equilibrium position, the springs 38 and 29 are further compressed.
2 moves upward.

In this way, when the front fork operates on the pressure side, the inner tube 11 resists the biasing force of the springs 38 and 29,
It descends while sliding inside the outer tube 12.

At the same time, the piston 15 fixed to the inner tube 11 also moves down within the outer tube 12, so the oil chamber A expands and the oil chamber B contracts.

At that time, since the volume changes of oil chamber A and oil chamber B are inversely proportional as described above, the second orifice 17
The same amount of oil that entered the oil sump chamber C through the oil sump chamber C
From there, it flows into the oil chamber A through the first orifice 16 and check valve 18.

Note that this damping force on the compression side is determined by the area of the orifice 17.

On the other hand, when the front fork is operating on the extension side, piston 1
5 rises inside the outer tube 12, causing the oil chamber A to contract and the oil chamber B to expand.

At that time, due to the volume increase/decrease relationship of oil chambers A and B similar to the above, the amount of oil discharged from oil chamber A to oil sump chamber C while being throttled by the first orifice 16 and generating a predetermined rebound damping force. The same amount of oil flows from the oil reservoir chamber C into the oil chamber B through the second orifice 17.

When the front fork operates on the compression side, the lower end of the inner tube 11 protrudes from the lower end of the bearing part 14, but since the present invention is provided with a protective cover 41, the inner tube 11 is completely protected from flying stones, dust, muddy water, etc. be done.

As a result, the surface of the inner tube 11 is prevented from being damaged by these flying stones and the like.

Although the above embodiment uses the metal spring 29 and the gas spring 38 in combination, the gas spring 38 alone can sufficiently provide the desired operation if the pressure is increased appropriately.

In addition, a freely sliding free piston (see part No. 26 in Part 2) is inserted between the cap 36 and the free piston 26 to separate the oil reservoir chamber C and the pressure gas chamber 27. A metal spring (not shown) may be interposed.

Note that the protective cover 41 may have an integral bottom shape with the outer tube 12.

As explained above, in this invention, the inner tube can be slidably inserted into the outer tube, and in a front fork where the inner tube protrudes to the lower end of the outer tube during compression side operation, an oil-tight seal is provided to cover the protruding part of the inner tube. A protective cover is formed at the lower end of the outer tube, and the oil reservoir inside the inner tube communicates with the protective cover, so the inner tube 11 can be completely protected from flying stones, dust, muddy water, etc. At the same time, it is possible to sufficiently expand the volume of the oil reservoir inside the inner tube, thereby compensating for oil leakage, suppressing the temperature rise of the hydraulic oil, and always exhibiting stable buffering characteristics. The gas sealed inside the inner tube, which has such a large volume, can function as a gas spring, creating a suspension spring (
It is also possible to replace the coil spring (coil spring) with one that is unnecessary or smaller, and the overall length of the inner tube can be shortened, increasing the degree of freedom when installing.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views of a conventional front fork, and FIG. 3 is a longitudinal sectional view of an embodiment of the present invention. 11... Inner tube, 12...
Outer tube, 13, 14...Bearing part, 1
5... Zest 7, I L 17... Orifice, 18... Check valve, 25---
--Pin, 26...Free piston, 27...
... Pressure gas chamber, 36 ... Cap, 37
... Enclosed valve, 41 ... Protective cover, A. B, C, C'... Oil room.

Claims (1)

[Scope of utility model registration request] The inner tube is slidably inserted into the outer tube, and the inner tube is supported by two bearings provided axially apart from each other in the outer tube. Two annular oil chambers are formed with the piston sandwiched between them, and these oil chambers are communicated with an oil reservoir chamber inside the inner tube through an orifice provided in the inner tube. In a front fork in which an axle support part is provided on the outer tube, a bottomed cylindrical protective cover is provided at the lower end of the outer tube to cover the lower part of the inner tube, and an oil reservoir is provided inside the protective cover that communicates with the inside of the inner tube. A front fork with a well-shaped chamber and an inner tube filled with pressure gas that presses the oil level.