JPH0452504Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention relates to the improvement of a front fork with a built-in damper for use in motorcycles, etc., and is designed to increase the damping force according to the stroke during compression operation. Regarding the position-dependent front fork.

<Prior art> For example, Japanese Patent Application Laid-Open No. 59-29578 discloses a front fork of this type of two-wheeled vehicle in which damping force adjustment during compression operation is position-dependent.
There is a device described in the publication.

That is, in this conventional device, several oil holes are provided at intervals near the top of a hollow piston rod, and a cylindrical guide is movably covered over the rod, and the guide is used to absorb the oil when the front fork is compressed. The oil holes are sequentially closed by moving the oil holes to the positions where the holes are provided.

As a result, at the beginning of the compression operation, the pressure oil in the cylinder passes through the hollow rod and is discharged into the inner tube from the multiple oil holes, but at the end of the compression operation, these oil holes are closed by the guide. As a result of the discharge being blocked by being closed,
This will generate a high damping force.

<Problems to be Solved by the Invention> By the way, according to this conventional device, during the compression operation, the flow rate of the hydraulic oil to be controlled by the oil hole is equal to the volume of the hollow rod entering the cylinder. Since it is a relatively small amount, it is sensitive to minute leaks caused by manufacturing errors during the previous control, so this must be taken into consideration to ensure sufficient accuracy in the mechanism configuration.

In addition, due to the arrangement of the oil holes, the hydraulic oil discharged from the oil holes will be ejected into the air-filled area above the inner tube, resulting in undesirable aeration.

Moreover, there is a concern that air may accumulate in the hollow part above the oil hole at the top of the hollow rod, and this may cause the damping force to become unstable, so conventional devices still require improvements. There was room left.

On the other hand, in this type of fork structure in which an inner tube and an outer tube fit and slide, the sliding contact area between the two tubes is large, and lubricant oil is not sufficiently supplied between the two tubes during sliding operation. For these reasons, there was a dislike for the high sliding resistance and lack of smooth operation.

Therefore, in order to eliminate the above-mentioned problems with the conventional device, the present invention measures an increase in the control flow rate of hydraulic fluid to the valve mechanism that variably controls the damping force during compression operation, thereby stabilizing the damping force. The object of the present invention is to develop a position-dependent front fork that can suppress aeration and measure the smoothness of the operation.

<Means for solving the problem> In order to achieve this objective, in the present invention, in the damper-internal type front fork mechanism, bearing members are arranged at both fitting ends of the inner tube and the outer tube, respectively. Then, a space is formed between these two tubes, and a check valve that opens when the tube is extended is placed on the inner wall of the inner tube in sliding contact with the outer circumference of the cylinder, and the position of the check valve is adjusted. Through holes are respectively opened at the upper and lower positions of the inner tube at the boundary to form a bypass flow path with the space between the two serving as a communication path, and two detection springs are arranged in series in the pressure side movement area of the inner tube. one end of the slide collar faces between the slide collar and the other end of the slide collar faces one of the through holes, and the opening area of the through hole is variably controlled by relative displacement of the collar with respect to the through hole. We provide a front fork with an internal damper.

<Function> The check valve disposed between the inner wall of the inner tube and the outer wall of the cylinder constituting the damper mechanism divides the hydraulic fluid chamber, which also serves as an air chamber, into two. By the stroke action of the front fork, the internal pressure of each of the two divided chambers increases or decreases in proportion to the volume of the piston rod and inner tube inserted into each chamber.

Due to this internal pressure difference between the chambers, hydraulic oil flows from the through holes formed on both sides of the check valve through the gap provided between the inner tube and the outer tube as a communication path. At this time, the check valve opens against the flow of hydraulic oil due to the difference in chamber pressure when the front fork moves in the extension direction.
Hydraulic oil flows in this direction with almost no resistance, and there is no damping force generated in this part, and cavitation due to negative pressure is generated in the chamber and cylinder interior on the side where the action in the direction of pressure reduction acts. There is no.

On the other hand, when the front fork is compressed, as the inner tube moves to the compression side, the two detection springs placed in this area contract in balance, and one end is moved between them. The facing slide collar moves in accordance with the stroke.

As a result, the other end of the collar faces one of the through holes, decreasing the opening area of the through hole, and increasing the damping force on the pressure side in this part while restricting the flow rate of hydraulic oil passing through it. It works like this.

Therefore, since the opening area of the through hole is controlled by the slide collar in accordance with the stroke of the front fork, the compression side damping force control can be performed as a position-dependent control operation.

The above-mentioned gap, which serves as a bypass path with these through holes as input and output ports, is designed to forcibly introduce lubricating oil (hydraulic oil) into the sliding part (bearing parts at both ends) between the inner tube and outer tube. It acts on

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

<Embodiment> Fig. 1 is a vertical sectional side view of the main part showing an embodiment of the present invention, showing a fitting sliding contact portion between an inner tube 1 and an outer tube 2 surrounding a cylinder 3 as a main body of a shock absorber with a built-in damper. Bearings 4 and 5 made of bearings or the like are provided at both ends, and an annular gap 6 is formed between these two tubes 1 and 2.

On the other hand, a check valve 7 is provided on the inner circumferential wall of the inner tube 1 and is in close sliding contact with the outer circumferential wall of the cylinder 3.
At the same time, through holes 8 and 9 are opened on both sides of the installation position of the valve 7 to reach the gap 6, respectively.

Further, two detection springs 10 and 11 having different spring constants are arranged in series between the tip of the inner tube 1 and the base of the outer tube 2 (see FIG. 2). In addition, the other end of the slide collar 12, with the bent piece at one end sandwiched between the two springs 10 and 11, is placed along the inner circumference of the inner tube 1 so as to face the rim of the through hole 9. I have it.

In addition, in FIG. 2 showing the overall configuration of this embodiment, 13 is a piston rod, 14 is a piston, 15 is a pressure side valve, 16 is a stopper and 1
7 indicates a shock absorbing spring.

According to this embodiment, when the inner tube 1 moves on the pressure side, the piston rod 13, which is integrally attached thereto, moves in the cylinder 3 to the right in FIG. 2, accompanied by the piston 14.
As a result, the internal volume of the cylinder 3 is reduced by the intrusion volume of the rod 13, and a corresponding amount of filled hydraulic oil is discharged out of the cylinder 3 via the pressure side valve 15. The inner tube 1 and the check valve 7 integrated therein enter the space between the cylinder 3 and the outer tube 2 where the hydraulic oil is discharged, so that the amount of hydraulic oil discharged from the cylinder 3 is reduced. In addition, the hydraulic fluid equivalent to the volume of the inner tube 1 and the check valve 7 that enters the chamber enters the other inner tube 1 which also serves as an air chamber separated from the chamber by the check valve 7. He is pushed towards the containment room.

This movement of the hydraulic fluid is carried out by the flow in the direction of the arrow in FIG. 1 through the through holes 8, 9 and the gap 6 formed as a bypass path while the check valve 7 is closed. Moreover, since the bearings 4 and 5 are reached between the inner tube 1 and the outer tube 2, which are located between 6 and 6, the hydraulic oil flowing through these bearings 4 and 5 is forcedly lubricated, and both tubes are 1 and 2 slide smoothly.

Then, by moving the inner tube 1 to the pressure side,
In the initial stroke range, one of the detection springs 11 with a small spring constant is compressed, and the other detection spring 10 with a large spring constant maintains its expanded state, so the slide collar is regulated by this detection spring 10. 12 moves along with the tube 1 without changing its relative position with the tube 1, but the detection spring 10 is
When the inner tube 1 reaches a stroke range where the inner tube 1 starts to pinch, the slide collar 12 also moves independently as the detection spring 10 reduces its deflection and changes its relative position with the inner tube 1.

With this operation of the slide collar 12, one end thereof faces the opening of the through hole 9 and gradually comes to cover it, so that the opening area decreases in accordance with the compression side stroke. This increases the flow resistance to the hydraulic oil passing through the through hole 9, increasing the compression damping force.

The through hole 9 formed by this slide collar 12
When the front fork is operated on the extension side under the operating state of position-dependent damping force control in which the opening area of Since the flow rate of hydraulic oil is small, check valve 7 opens at this time to allow a large amount of hydraulic oil to pass through. Therefore, it is possible to prevent cavitation that may occur during the extension side operation in such a case.

<Effects of the invention> As described above, according to the front fork of the invention, the two through holes at the upper and lower positions communicating with the gap formed by the bearing member disposed between the sliding contact between the inner tube and the outer tube are The opening area of one of the through holes is changed by a slide collar which is provided on the outer periphery of the cylinder with the contact check valve as a boundary, and which is displaced relative to the inner tube in response to the pressure side stroke of the inner tube. The flow of hydraulic oil, which is increased by the sum of the intrusion volumes of the piston rod, inner tube, and check valve structure, generated in the content chamber and the outer cylinder space can be controlled by changing the opening area, so that the pressure side stroke can be controlled. The proportional position-dependent compression side damping force can be adjusted stably by increasing the flow of hydraulic oil, and the check valve function of the rebound side opening allows adjustment of the proportional position-dependent damping force when the position-dependent damping force is generated. It is possible to prevent cavitation from occurring even during expansion-side operation, and since the flow rate is controlled by the through hole in the hydraulic oil-filled area at the tip of the inner tube, there is no risk of the hydraulic oil flowing there mixing with the air in the pressure chamber. This is extremely effective in suppressing aeration, and furthermore, since the hydraulic oil flowing through the through hole can be forcibly introduced into the bearing member through the gap, the lubricity of these bearing parts is improved. The front fork of the present invention is extremely useful in practical use, as it allows the front fork to extend and retract very smoothly.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of essential parts showing an embodiment of the front fork of the present invention, and FIG. 2 is a half-cut longitudinal sectional side view showing the overall configuration of the embodiment. 1...Inner tube, 2...Outer tube, 3...Cylinder, 4, 5...Bearing, 6...
... Between, 7... Check valve, 8, 9... Through hole, 1
0 and 11...Detection spring, 12...Slide collar.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a front fork mechanism with an internal damper, bearing members are provided at both fitting ends of the inner tube and outer tube to form a space between these two tubes. On the other hand, a check valve that opens by extension action is placed on the inner wall of the inner tube in sliding contact with the outer periphery of the cylinder, and furthermore, through holes are drilled at the upper and lower positions of the inner tube, respectively, with the position of the check valve as the border. to constitute a bypass flow path with the space between them as a communication path, and
One end of the slide collar faces between two detection springs arranged in series in the compression side movement area of the inner tube, and the other end of the slide collar faces one of the through holes, so that the relative displacement of the collar with respect to the through hole is controlled. Therefore, a front fork with a built-in damper is configured to variably control the opening area of the through hole. (2) The damper-internal type front fork according to claim 1, wherein the gap is an annular lubricating oil supply path reaching the bearing members at both ends.