JPS6238404Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary valve mechanism for a shock absorber, and more particularly to an auxiliary valve mechanism for a shock absorber that is most suitable for being incorporated into a front wheel suspension system of an automobile.

The shock absorber of the front wheel suspension system does not generate sufficient damping force when the piston rod expands due to the load acting on the vehicle when the vehicle suddenly starts or accelerates. Therefore, when starting suddenly or accelerating suddenly, the front of the car is lifted upward.
A so-called nose-up phenomenon occurs.

Conventionally, countermeasures against nose-up have been taken such as changing the geometrical arrangement of the suspension system, modifying the damping force characteristics of the shock absorber, or increasing or decreasing the spring constant of the spring provided in the suspension system, but none of these methods are yet satisfactory. has not been reached yet. This is because the specification settings of the above items related to nose up are contradictory.
For example, the higher the damping force of the shock absorber is, the better from the standpoint of nose-up countermeasures, but this results in poor riding comfort, which is a trade-off, so it cannot be determined solely by its effect on nose-up.

Accordingly, an object of the present invention is to provide an auxiliary valve mechanism for a shock absorber that exhibits damping force characteristics that are effective for nose-up while minimizing adverse effects.

The present invention is an auxiliary valve mechanism provided on a piston rod that is connected to the piston at its lower end and whose upper end projects outward from the cylinder. This auxiliary valve mechanism is an auxiliary valve mechanism for an automobile shock absorber in which the inside of the cylinder is partitioned into two liquid chambers by a piston, and the two liquid chambers can communicate with each other via a bypass provided in the piston rod. A valve body disposed within the piston rod for opening and closing the bypass, means for operating the valve body for generating an operating force that increases as the engine speed increases, and means for detecting the speed of the vehicle. The valve body is configured to be released from the operating force of the operating means and open the bypass when the speed of the vehicle exceeds a predetermined speed.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the auxiliary valve mechanism 10 of the present invention is installed in a piston rod 16 of a shock absorber known per se, which comprises a cylinder 12, a piston 14 and a piston rod 16.

The cylinder 12 consists of an inner cylinder 18 and an outer cylinder 20, and a piston 14 slides on the inner circumference of the inner cylinder 18.
Piston rod 16 is connected at its lower end to piston 14 and at its upper end to cylinder 12.
The rod guide 22 and the seal member 24 protrude to the outside. When the piston rod 16 expands and contracts, the expansion valve mechanism 2 provided on the piston 14
6 and a compression valve mechanism 28 generate damping force.

In the present invention, the damping force characteristics of the shock absorber are modified by the auxiliary valve mechanism 10 so as to be effective as a countermeasure against nose-up. The auxiliary valve mechanism 10 is provided in association with a hole 30 made in a piston rod 16, and includes an auxiliary piston 32 as a valve body, a spring 34, a spring receiver 36, an auxiliary port 38, an orifice 40, and a pipe 42. and a valve 44.

In the illustrated example, the hole 30 is drilled through the piston rod 16 in the axial direction thereof, and the large-diameter hole portion 4 located below with an intermediate shoulder 31 in between.
6 and a small diameter hole portion 47 located above. If the hole 30 is penetrating, its lower end is closed to perform the function of the orifice 40, and its upper end is connected to a pipe 42 or is closed.

The auxiliary piston 32 is fitted with an O-ring 48 in the middle, and slides in the hole portion 46 in a fluid-tight manner by the O-ring 48.

The spring 34 is hooked to a spring receiver 36, and its upper end abuts the auxiliary piston 32 to bias the auxiliary piston 32 upward. As a result, the auxiliary piston 32 is pressed against the shoulder 31. The spring force of the spring 34 is large enough to allow the auxiliary piston 32 to move downward against the spring force when fluid at a predetermined pressure is supplied to a pipe 42, which will be described later. In other words, when the pressure in the pipe 42 does not reach the predetermined pressure, the auxiliary piston 32 is kept biased upward by the spring 34.

In the illustrated example, the spring receiver 36 is integral with a threaded member 50 that closes the lower end of the hole portion 46, and has dimensions that cause the spring 34 to be in a compressed state when the threaded member 50 is fully screwed into the piston rod 16. . The spring receiver 36 also serves as a stopper when the auxiliary piston 32 moves downward.

The auxiliary port 38 communicates the hole portion 46 with a fluid chamber 52 in the inner cylinder 18 located above the piston 14 when the auxiliary piston 32 is biased upwardly, and also communicates with this fluid chamber 52 when the auxiliary piston 32 is moved downwardly. It is provided at a position where it is blocked by the auxiliary piston 32.

The orifice 40 connects the hole portion 46 closed by the screw member 50 to the liquid chamber 54 below the piston 14.
Connect to. A bypass is formed by the orifice 40, the hole portion 46, and the aforementioned auxiliary port 38, and the upper liquid chamber 52 and the lower liquid chamber 54 can communicate with each other via this bypass.

The piping 42 supplies pressurized fluid to the bore 30 and is connected to the bore 30 at the piston rod 16 projecting outward from the cylinder 12. In the example shown, the piping 42 is connected to the piston rod 16 by a fitting 56 threaded into the upper end of the bore 30 and communicates with the bore portion 47. This piping 42
The other end of the engine pump 58 is connected to the engine pump 58 . The other end of the pipe 42 is connected to a means for generating pressure proportional to the engine speed, like the engine pump in this example.

A valve 44 is incorporated into the piping 42 . This valve 44
is constituted by, for example, an electromagnetic on-off valve that has two operations of opening and closing, and is opened and closed by a signal from the speed detection means 60. In the illustrated example, the speed detection means 60
are proximity switches placed in the first and second gear positions of the transmission 62, which output a signal only when the transmission is in the first and second gear positions, and this signal causes the valve to 44 is open. Therefore, when the shift is to the third and fourth speeds and the vehicle is moving at high speed, the signal is no longer output and the valve 44 is closed.

The speed detection means 60 can also be configured by a speedometer. In this case, for example, a car
A signal is output from the speedometer to the valve 44 to keep it open until the speed reaches 40 km/h, and when this speed is exceeded, the output of the signal is stopped and the valve 44 is closed.

When using the shock absorber attached to the front wheel suspension system of a car, the oil pressure of the engine oil pump 58 is low and the auxiliary piston 3
No force is generated for 2 to overcome the spring 34. Therefore, the auxiliary piston 32 is in the illustrated position, and when the shock absorber is extended, the oil passage becomes the extension valve mechanism 26 together with the auxiliary port 38, hole portion 46, and orifice 40, and the damping force characteristics at this time are This becomes A in Figure 2.

Next, when the engine speed is high and the oil pressure from the engine oil pump 58 exceeds a predetermined pressure set in the spring 34, such as during sudden acceleration, the auxiliary piston 32 moves downward and hits the spring receiver 36. come into contact with In this state, the auxiliary port 38 is blocked, so there is no flow of oil through the auxiliary port 38, and the oil flows only through the extension valve mechanism 26, exhibiting the damping force characteristic of B in Fig. 2. That will happen. In other words, a high damping force can be obtained in the low speed range of the piston, and nose-up can be suppressed during sudden start or sudden acceleration.

When a car increases its speed and reaches a certain speed,
Since the valve 44 in the pipe 42 is closed, the supply from the engine oil pump 58 is stopped, the auxiliary piston 32 is pushed up by the spring 34, and the auxiliary port 38 is brought into communication. Auxiliary piston 32
In order to ensure the return of the
4 incorporates an aperture 66 and communicates with a reservoir tank 68.

According to the present invention, the auxiliary valve mechanism provided on the piston rod can suppress nose-up during sudden starts or sudden accelerations at low speeds, thereby improving steering stability and riding comfort. Moreover, when the vehicle speed reaches a predetermined speed, the valve body of the auxiliary valve mechanism opens the bypass, so the ride comfort does not deteriorate during high-speed driving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the auxiliary valve mechanism according to the present invention, and FIG. 2 is a characteristic diagram of the damping force of a shock absorber equipped with the auxiliary valve mechanism. 10: Auxiliary valve mechanism, 12: Cylinder, 14: Piston, 16: Piston rod, 30: Hole, 3
2: Auxiliary piston, 34: Spring, 36: Spring receiver, 38: Auxiliary port, 40: Orifice, 4
2: Piping, 44: Opening/closing valve, 60: Speed detection means.

Claims (1)

[Scope of utility model registration request] This is an auxiliary valve mechanism for an automobile shock absorber in which the inside of a cylinder is partitioned into two liquid chambers by a piston, and both liquid chambers can communicate with each other via a bypass provided in a piston rod. a valve body that opens and closes the bypass; means for operating the valve body that generates an operating force that increases as the engine speed increases; and means for detecting the speed of the vehicle; An auxiliary valve mechanism for a shock absorber, wherein the body is released from the operating force of the operating means and opens the bypass when the speed of the vehicle exceeds a predetermined speed.