JPS6188034A - Hydraulic damper of variable damping force type - Google Patents

Abstract

PURPOSE:To have a damping force varied in accordance with an expansion stroke and then make the force constant on the way of the stroke by having a pressing force, varied in accordance with the stroke, operate on a damping force generating valve at the early time of the expansion stroke. CONSTITUTION:A cylindrical guide member 8 is screwed up on one end of a piston rod 3. A valve guide 9 and a spring guide 10 are engaged on the external face of the member 8 as they can be slided vertically. Springs 12 and 13 are disposed between a valve guide 9 and a spring guide 10 and between the spring guide 10 and a cylinder 2. The valve guide 9 makes contact with a damping force generating check valve 7 disposed under a piston 4. During an expansion stroke of the cylinder, the check valve 7 is first subjected to the pressing forces of the springs 12 and 13 and then, on the way, subjected to the pressing force of the spring 12 only, whereby making the damping force constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable damping force type hydraulic damper.

(Prior art) For example, if the link mechanism of a motorcycle's rear suspension has a progressive ratio characteristic, a hydraulic damper used as a rear cushion has a corresponding damping force characteristic. For example, at the beginning of the extension stroke, the damping force depends on the stroke. It is required that the damping force is maintained constant from the middle to the fully extended state.

(Problems to be Solved by the Invention) However, in conventional hydraulic dampers, although the damping force can be changed depending on the stroke, the damping force cannot be kept constant from the middle of the stroke.

Therefore, it is an object of the present invention to provide a variable damping force type hydraulic damper that can maintain a constant damping force from the middle of the stroke.

(Means for Solving the Problems) In order to achieve the object of "1.1", the present invention binds a kite material to the piston side end of the piston rod inserted into the cylinder, and attaches the kite material to the guide material. is a valve guide that presses the outer circumference of a check valve provided on a piston toward the closing side;
A hydraulic damper of the present invention was constructed by slidably fitting a spring guide whose movement is regulated by the guide material, and interposing springs between the valve guide and the spring guide and between the spring guide and the cylinder.

(Function) During the extension stroke, the spring guide moves integrally with the guide material, so the distance between the spring guide and the valve guide is kept constant, and the check valve is pressed with a constant force. The flow resistance of the oil flowing here is kept constant, and as a result, the damping force is kept constant.

(Example) An example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a partially cutaway sectional view of a variable damping force type hydraulic damper according to the present invention, FIG. 2 is an enlarged detailed view of the first conventional part, and FIG. 3 is a broken sectional view showing the action of the hydraulic damper. Figure 4 is a damping force characteristic diagram.

In the hydraulic damper (1) shown in Fig. 1, (2) is a cylinder, into which a piston rod (3) is inserted from above, and at the lower end of the piston rod (3) is a cylinder (2). 2) A piston (4) that fits vertically and slidably on the inner periphery is connected with a nut (5). A plurality of oil holes (6)... are bored in the piston (4),
A check valve (7) to open and close the oil hole (6) is provided on the lower surface of the piston (4).

By the way, a cylindrical guide member (8) is screwed onto the outer periphery of the nut (5), and a valve guide (9) and a spring guide (10) are fitted onto the outer periphery of this so as to be able to slide vertically. are doing. And between the valve guide (9) and the spring guide (lO) and between the spring guide (10)
There is a spring (12) between the and spring seat (11).
, (13) are interposed, and the valve guide (9) receives the elastic force of the spring (12) and presses the outer periphery of the check/help (7) toward the closing side as shown in Fig. 2. There is. Note that the lower end of the guide member (8) has a spring seat (
10) is formed with a flange portion (8a) that restricts downward movement.

On the other hand, the upper inner circumference of the cylinder (2) is equipped with a bistor rod (
3) An oil seal (10) and a rod guide (15) are fitted that slide on the outer periphery. Also, the piston rod (3)
) and a cushion spring (18) is stretched between spring seats (18) and (17) provided on the outer periphery of the upper part of the cylinder (2) and the lower part of the cylinder (2).

Therefore, inside the cylinder (2), the oil chamber (
SL) and (S2), and these oil chambers (91)
, (S2) are filled with hydraulic oil.

Next, the action of this hydraulic damper (1) will be explained.

At the beginning of the extension stroke, the piston (4) moves toward the cylinder (
2), the spring (13) is compressed and its spring load is high, and as shown in FIG. 12) is compressed.

The valve guide (8) presses the check valve (7) with strong force. As a result, the check valve (7) is pushed open to increase the flow resistance of the oil passing therethrough, and the damping force generated based on this flow resistance increases. and,
As the extension stroke progresses and the piston (0) moves upward in the cylinder (2), the spring (13) gradually expands and its elastic force decreases, so the spring guide (lO) moves downward along the guide material (11). As a result, the spring (
12) also extends, and the check valve (
7) The pressing force gradually weakens. Therefore, the flow resistance of the sleeve passing through the check valve (7) is reduced, and the damping force is as shown in Figure 4.

It changes along straight line AB.

Finally, in the middle of the stroke, the spring guide (
! 0) rests against the lower end flange portion (8a) of the guide member (8) as shown in FIG. 1, and the distance between the spring guide (10) and the valve guide (9) is kept constant. The spring (12) interposed between the two (9) and (10) also maintains a constant length, and the check valve (7)
) is pressed with a constant force, so the damping force remains constant until the fully extended state. The damping force characteristic at this time is the fourth
In the figure, it is indicated by a straight line BC.

(Effects of the Invention) As is clear from the above description, according to the present invention, the cylinder is inserted into the cylinder. A guide material is attached to the end of the piston rod on the piston side, and the guide material includes a valve guide that presses the outer wall of a check valve provided on the piston toward the closing side, and the movement of the guide material is regulated by the guide material. Since the spring guide is slidably inserted between the valve guide and the spring guide and between the spring guide and the cylinder, the spring guide moves together with the guide material during the extension stroke. ,
Therefore, the distance between the spring guide and the valve guide is kept constant, and the check valve is pressed with a constant force.
The flow resistance of the oil flowing here is kept constant, and the damping force is kept constant.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view of a variable damping force type hydraulic damper according to the present invention, Fig. 2 is an enlarged detailed view of the first conventional part, and Fig. 3 is a cutaway cross-sectional view showing the action of the hydraulic damper. , FIG. 4 is a damping force characteristic diagram. In one drawing, (1) is a variable damping force hydraulic damper, (2 is
) is the cylinder, and (3) is the piston rod. (4) is a piston, (7) is a check valve, (8) is a kite member, (9) is a valve guide, (10) is a spring kite, and (12) and (13) are springs.

Claims (1)

[Claims] A piston rod is inserted into the cylinder, and a piston is attached to one end of the piston rod, which is fitted to the inner circumference of the cylinder so as to be slidable up and down, and is provided with a check valve for opening and closing an oil hole provided in the piston rod. A hydraulic damper comprising:
A guide member is attached to the end of the piston rod on the piston side, and the guide member includes a valve guide that presses the outer circumference of the check valve toward the closing side, and a spring guide whose movement is regulated by the guide member. A variable damping force type hydraulic damper, characterized in that a valve guide and a spring guide are slidably fitted, and a spring is interposed between the valve guide and the spring guide and between the spring guide and the cylinder.