JPS6264603A - Bottom hit preventive device for wheel suspension hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To allow parts involved to be easily assembled with a cylinder by allowing a damping unit to be composed of an auxiliary cylinder and an auxiliary piston equiped with a check valve which permits working fluid to pass through only surface holes which communicate the inside of the auxiliary cylinder with its outside, and also to flow only into the inside. CONSTITUTION:A damping unit D, which is provided at the outside of the compression stroke of a piston 23 in a cylinder 21 of a hydraulic damper 17b, is composed of an auxiliary cylinder 45 which is integrally formed with a bulkhead 33, and of a auxiliary piston 47. And shaft holes 53 are made on the auxiliary piston 47 so as to be opened to the inside of the auxiliary cylinder 45, and the plural number of small holes 54, 54... are simultaneously made on the wall surface so as to communicate the shaft hole 53 with the outside of the auxiliary cylinder 45. And a ball valve 45 is provided where the valve is energized by a spring 65 from the inside of the cylinder 45 toward a communication hole 61, which is formed at the tip end of the auxiliary piston 47 for communicating the outside of the cylinder 45 through the shaft holes 54. This configuration allows the shock of the piston 23 due to collision to be absorbed. And thus, the assembly work can be easily done.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a bottoming prevention device for a hydraulic shock absorber used in a wheel suspension system.

[Prior Art and Progress until Completion of the Invention] When a motorcycle is running, the wheels are temporarily subjected to large pressure from the road surface, which may cause so-called bottoming out in the hydraulic shock absorber for the wheel suspension system.

When this bottoming out occurs, the ride comfort of the vehicle becomes worse,
Conventionally, there are (1) a method of using a multi-rate spring as a buffer spring for a wheel suspension system, (2) a method of increasing the capacity of a bump stop in a hydraulic shock absorber for a wheel suspension system, (3), A method of increasing the damping force at the end of the maximum compression stroke in a hydraulic shock absorber of a wheel suspension system using a link mechanism has been considered.

However, the methods (1) and (2) have a negative impact on tire traction on the wheels, and (3)
) method requires a complicated structure and is difficult to manufacture due to the structure of vehicles, especially motorcycles.

In order to eliminate this drawback, the applicant has proposed a device in which a damping unit is installed outside the compression stroke end of the piston in the hydraulic shock absorber, and has already filed an application (Japanese Patent Application No. 11320/1982).

However, in the device according to this application, since the damping unit has not been integrally combined with the cylinder in the past, there is a problem in that it takes time and effort to assemble the damping unit into the cylinder. .

[Means to solve the above problem]

The problem with the prior art is that the damping unit installed in the cylinder of the hydraulic shock absorber is composed of an auxiliary cylinder and an auxiliary piston that moves forward and backward within the auxiliary cylinder, and that the auxiliary piston is provided with internal and external connections to the auxiliary cylinder. This was achieved by forming a communicating hole and installing a check valve that allows hydraulic oil to pass only from the outside to the inside of the auxiliary cylinder.

[Action of the invention]

Since the bottoming prevention device for the hydraulic shock absorber for a wheel suspension system according to the present invention is configured as described above, the damping unit was previously assembled to the cylinder (hydraulic shock absorber) in an integrated manner. As a result, in this bottoming prevention device, it is extremely easy to assemble the damping unit to the cylinder.

[Explanation of Examples]

Hereinafter, the present invention will be described in detail based on the drawings.

In FIG. 2, 11 is a frame of the motorcycle, and 13 is a rear arm pivotally supported by the frame. This rear arm 13 pivotally supports a rear wheel 15 at its rear end.

17 is a hydraulic shock absorber, which connects the frame 11 and the rear arm 1.
3 (with a link mechanism 19 interposed therebetween).

In FIG. 3, the hydraulic shock absorber 17 consists of a shock absorbing spring 17a and a hydraulic damper 17b.

The hydraulic damper 17b is a cylinder 21 filled with hydraulic oil O.
It has a piston 23 that moves forward and backward within the cylinder 21, and a piston rod 25 that holds the piston 23 at one end and projects the other end outside the cylinder 21.

A reserve tank 29 is divided into a pressurized gas chamber 29a and a hydraulic oil chamber 29b via a free piston, and is communicated with the cylinder 2I via a rubber hose 31. Hydraulic oil 0 reciprocates between the reserve tank 29 and the cylinder 2I to adjust the change in volume of the piston rod 25 inside the cylinder 21 that occurs when the piston 23 moves back and forth inside the cylinder 21.

Next, D is a damping unit, which is installed outside the compression stroke end of the piston 23 in the cylinder 21. This damping unit D receives a collision with the tip of the piston rod 25 when the piston 21 of the hydraulic shock absorber 17 reaches the maximum compression end, and damps the impact to prevent the piston 23 from bottoming out.

This damping unif 1-D will be explained in detail based on FIG.

A partition wall member 33 is fitted into the cylinder 21. Reference numeral 45 denotes an auxiliary cylinder, which is integrally formed with the partition wall member 33. Note that the auxiliary cylinder 45 does not necessarily have to be integrally formed. The auxiliary cylinder 45 has an axial direction aligned with the direction of movement of the piston 23 and is open to the piston 23 side. 47 is an auxiliary piston;
It is fitted into the auxiliary cylinder 45 so that it can move forward and backward. This auxiliary piston 47 moves forward and backward in the same direction as the piston 23. A compression spring 49 is installed inside the auxiliary cylinder 45 to elastically repel the auxiliary piston 47 outward. Note that 51 is an elastic member that prevents the auxiliary piston 47 from being removed, and 52 is an elastic member that buffers the collision between the auxiliary piston 47 and the auxiliary piston 47.

Next, 53 is a shaft hole, which is formed in the auxiliary piston 47. This shaft hole 53 opens only into the auxiliary cylinder 45. 54,54. ... are pores formed in the wall surface of the auxiliary piston 47. There are a plurality of small holes 54, each of which communicates the shaft hole 53 of the auxiliary piston 47 with the outside of the auxiliary cylinder 45. Therefore, when the auxiliary piston 47 is pressed by the collision of the piston 23, the hydraulic oil 0 in the auxiliary cylinder 45 is discharged to the outside of the auxiliary cylinder 45 through the pore 54, so that a damping force is generated and the bottom of the piston 23 is pressed. Thrusting is prevented. Note that when the auxiliary piston 47 is pushed into the auxiliary cylinder 45 by the piston 23, the outer side of the auxiliary cylinder 45 and the shaft hole 53
Since the number of pores 54 that communicate with each other decreases, the damping force gradually increases.

Further, L is a check valve, which is formed at the tip of the auxiliary piston 47. This check valve includes a communication hole 61 formed at the tip of the auxiliary piston 47 and communicating between the shaft hole 54 and the outside of the auxiliary cylinder 45, and a compression spring 65 inside the communication hole 61.
It is composed of a ball valve 63 which is pressed down by a ball valve 63. This check valve is connected to the compressed auxiliary piston 47.
It opens only when it returns to its original state (state !3 in Figure 1).

〔Effect of the invention〕

Since the bottoming prevention device for a hydraulic shock absorber for a wheel suspension system according to the present invention is configured as described above, the damping unit was previously assembled to the cylinder (hydraulic shock absorber) in an integrated manner. As a result, in this bottoming prevention device, it is extremely easy to assemble the damping unit to the cylinder.

[Brief explanation of drawings]

The drawings show an embodiment of the bottoming prevention device for a hydraulic shock absorber for a wheel suspension system according to the present invention, and FIG. 1 is an enlarged cross-sectional view of a portion of FIG. 3, and FIG. 2 is a front view of this embodiment. FIG. 3 is an enlarged partial sectional view of the hydraulic shock absorber in FIG. 2. 21 ... Cylinder 23 ... Piston 25 ... Piston rod 45 ... Auxiliary cylinder 47 ... Auxiliary piston 54 ... Pore D ... Damping unit L ... Check valve (61) ...Communication hole, 63...Valve ball, 65...Compression spring) 0...Hydraulic oil

Claims (1)

[Claims] (1) A cylinder filled with hydraulic oil, a piston that moves back and forth within the cylinder, and a piston rod that holds the piston at one end and projects from the cylinder at the other end;
a damping unit installed outside the compression stroke end of the piston, the damping unit comprising an auxiliary cylinder fixed to the cylinder and an auxiliary piston moving back and forth within the auxiliary cylinder, and the auxiliary piston While moving forward and backward in the same direction as the forward and backward direction of the piston, the piston can reach the end of the maximum compression stroke while pushing the auxiliary piston, and the auxiliary piston is elastically projected from the auxiliary cylinder in the direction of the piston, Furthermore, this auxiliary piston has a pore that communicates between the inside and outside of the auxiliary cylinder, and a check valve that allows hydraulic oil to pass only from the outside to the inside of the auxiliary cylinder is installed. Bottoming prevention device for hydraulic shock absorbers.