JPH0547435B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field of the Invention] The present invention relates to a device for adjusting the damping force of a shock absorber of a rear wheel suspension system of a vehicle such as a so-called two-wheeled motor vehicle. automatically make it smaller,
The load on the damping force adjustment device for braking operation is reduced by reducing the operating force to prevent the rear part of the vehicle body from jumping up during braking, and the accuracy of the correlation between the depression stroke of the brake pedal and the reduction in the damping force. It is something that can improve.

[Prior art]

The so-called shock absorber for the rear wheel of a two-wheeled motor vehicle has sufficient elastic strength to ensure stability under normal driving conditions, and is also used to damp vertical vibrations of the rear wheel caused by uneven road surfaces. It has a fairly strong damping force.

There are various types of rear wheel shock absorbers for vehicles such as motorcycles, but the reserve tank is separate from the shock absorber cylinder and the gas pressure is considerably high. It is known that the hydraulic pressure in the cylinder of the shock absorber is high, and therefore, when the force in the direction of contraction of the hydraulic shock absorber increases, the hydraulic resistance force against the movement of the piston in the contraction direction becomes small. There is. In order to prevent this, it has been known to provide a base valve with a fixed orifice on the cylinder head side, and to communicate the cylinder head side with the oil chamber of the reserve tank through this base valve. There is no problem with this conventional hydraulic shock absorber because it exhibits the desired shock absorbing characteristics under normal driving conditions due to the desired elastic strength and strong damping force.However, the elastic strength of the hydraulic shock absorber is large and the damping force is large. is relatively large, so when the vehicle is tilted forward on a downhill slope, the load on the front wheels increases and the load on the rear wheels decreases due to the forward tilt of the vehicle. The damping force of the hydraulic shock absorber increases and ride comfort deteriorates. In addition to this, when the braking force suddenly increases and the vehicle decelerates, the rear of the vehicle tends to lift up due to running inertia. If the rear wheels ride on a convex part of the road surface during deceleration due to braking, the rear part of the vehicle body is pushed up significantly by the rear wheels, and when strong braking is suddenly applied, the rear part of the vehicle body lifts and the ride quality deteriorates in particular.

Therefore, in order to prevent deterioration of ride comfort during sudden braking, it is desirable to automatically reduce the damping force of the hydraulic shock absorber during braking to soften the rear wheel hydraulic shock absorber.

Furthermore, reducing the damping force more than necessary during braking not only impairs the damping characteristics but is also undesirable from the standpoint of vehicle stability.

[Problem of the present invention]

The present invention is based on the above-mentioned prior art, and relates to automatically reducing the damping force of a rear wheel hydraulic shock absorber in conjunction with the operation of the brake pedal during braking. The objective is to reduce the damping force as much as possible and to improve as much as possible the accuracy of the correlation between the strength of the braking force, that is, the depression stroke of the brake pedal, and the rate of decrease in the damping force.

[Measures taken to solve the problem]

The measures taken to solve the above issues are the following elements (a)
It is composed of ~(d).

(a) A variable orifice chamber having a communication port communicating with the central chamber in the cylinder and a communication port communicating with the end chamber is attached to the outer side of the hydraulic shock absorber; (B) the variable orifice chamber (c) a cylindrical sliding member having an orifice valve seat is fitted into the cylindrical sliding member, and the sliding member is urged by a spring to return the sliding member in a direction that reduces the opening cross-sectional area of the orifice; (d) a valve member facing the orifice valve seat of the sliding member in conjunction with a brake pedal, such that the sliding member is caused to slide against the return spring by the operation of the brake pedal; is fixed in the orifice chamber so that the position of the valve member can be adjusted in the axial direction, and the strength of the restriction by the orifice is adjusted by adjusting the axial position of the valve member.

[Effect]

The end chamber and the center chamber, which communicate with the oil chamber of the reserve tank, communicate with each other via a fixed orifice of the base valve, a variable orifice formed by the orifice valve seat of the sliding member, and the valve member. The damping effect of the hydraulic shock absorber is exerted by the damping force caused by these and the damping force caused by the fixed orifice of the piston of the hydraulic shock absorber.

Therefore, by adjusting the axial position of the valve member (initial adjustment), the strength of the throttling of the variable orifice by the valve member and the valve seat is adjusted, and the pressure of the hydraulic shock absorber under normal running conditions is adjusted. Damping force is adjusted.

When the brake pedal is depressed, the sliding member moves against the return spring, and as the sliding member moves, the distance between the orifice valve seat and the valve member increases. . Therefore, the strength of the restriction by the variable orifice formed by this orifice valve seat and the valve member becomes small.
This automatic adjustment operation of the variable orifice simply moves a cylindrical sliding member linearly along the inner wall surface of the variable orifice chamber against a weak return spring, and the sliding member itself has an extremely small diameter. Due to its small size and low mass, the sliding member can be operated very smoothly with relatively little force. Therefore, the resistance of this sliding member to the operation of the brake pedal is negligibly small.

Furthermore, the relationship between the depression stroke of the brake pedal and the sliding stroke of the sliding member is physically defined by the interlocking mechanism of the two, and the relationship between the sliding stroke of the sliding member and the rate of change of the cross-sectional area of the variable orifice is The relationship between is physically defined by the shape of the valve member and the shape of the orifice valve seat of the sliding member, and furthermore, a change in the throttle strength of the variable orifice from its initial state is a change in the cross-sectional area of the variable orifice. Uniquely defined by. Therefore, there is an extremely high correlation between the depression stroke of the brake pedal and the reduction rate of the throttle strength of the variable throttle, and the damping force can be reduced as necessary and sufficient according to the braking operation, and the brake pedal It is possible to more appropriately control the damping force of the rear wheel shock absorber in conjunction with depression (automatic adjustment of the damping characteristics of the rear wheel shock absorber) in accordance with an increase in the braking force.

〔Example〕

Next, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

1 is a frame of a two-wheeled motor vehicle, and 2 is a rear arm. The rear arm holds a rear wheel 3 via an axle to the rear wheel, and its front end is pivoted to the frame 1 by a pivot shaft 4 so as to be swingable in the vertical direction. Reference numeral 5 denotes a hydraulic shock absorber, which is interposed between the frame 1 and the rear arm 2 and constitutes a rear wheel suspension system.

This hydraulic shock absorber 5 consists of a shock absorbing spring 51 and a hydraulic damper 52. The hydraulic damper 52 includes a cylinder 53 filled with hydraulic oil O, a piston 54 that slides inside the cylinder 53, and a piston rod 55 that holds the piston 54 at one end and projects the other end outside the cylinder 53. are doing. piston 54
The inside of the cylinder 53 is divided into two chambers, and the piston 54 is provided with an orifice (not shown) to generate a damping force during the compression and expansion operations of this hydraulic damper.

By the way, as mentioned above, as the piston 54 reciprocates within the cylinder 53 filled with hydraulic oil O, the piston rod 55 is recessed into the cylinder 53.
Since the volume of the oil changes, it is necessary to adjust the hydraulic oil O to match this volume change.

For this reason, a reserve tank 56 is provided separately from the cylinder 53 and communicated with it through a rubber hose 57. The interior of the reserve tank 56 is divided by a free piston 58 into an oil chamber and a gas chamber filled with high-pressure nitrogen gas G.

59 is a base valve, and a hydraulic damper 52
These are separate fixed orifices for the regulated flow of the hydraulic oil O associated with the compression and expansion operations of the hydraulic fluid O. Reference numeral 6 denotes a variable orifice, which is provided in parallel with the base valve 59.

In this embodiment, the damping force accompanying the extension operation of the hydraulic damper 52 is generated by the orifice of the piston 54, and the diameter of the orifice of the base valve 59 that opens during the extension operation is increased, so that the variable orifice 6 functions exclusively as an orifice for adjusting the damping force during compression operation.

Next, the structure of the variable orifice 6 will be explained with reference to FIG. Here, for the sake of convenience in the following explanation, they will be referred to as a central chamber A and an end chamber B within the cylinder 53, which are partitioned by the base valve 59.

The cylinder 53 near the base valve 59 is provided with an orifice chamber 63 having a communication port 61 with the A chamber and a communication port 62 with the B chamber. Inside this orifice chamber 63, a sliding member 64 is provided.
and the valve member (needle valve) 65 constitute an orifice S. The sliding member 64 has the aforementioned communication ports 61 and 6.
A flow path 64a is provided that communicates with the flow path 64a.
An orifice valve seat 64b is formed in the middle.

Also, one end of this sliding member 64 is connected to the orifice chamber 6.
3, an inner wire of Bowden wire is attached thereto, and a communication mechanism 8 with the brake pedal 7 is provided. 64c is a return spring that returns this sliding member 64 to its original position.

On the other hand, a needle valve 65 is provided at the other end of the orifice chamber 63.
A screw member 66 is provided to hold the screw member 6.
A pin 67 passing through two long holes 66a provided in 6
The orifice S can also be installed by manually turning the nut 68.
It is possible to adjust the distance between the two.

Therefore, when the brake pedal 7 is depressed in the direction of the arrow in the figure to brake, the inner wire of the Bowden wire, which is the interlocking mechanism 8, is pulled by the pulley 71 fixed to the brake pedal 7, and as a result, the sliding member 64 moves in the direction shown in the figure. Since it moves in the middle right direction, the distance between the orifices S is expanded, and the damping force accompanying the compression operation of the hydraulic damper is reduced.

Next, another embodiment shown in FIG. 4 will be described.

This embodiment is suitable as a brake device for a hydraulic brake that transmits a brake pedal operation signal as hydraulic pressure to a cylinder of a brake caliper.

That is, in the previously described embodiment, a Bowden wire or the like was used as the interlocking mechanism, but in this embodiment,
The difference is that a branch circuit is provided from the hydraulic circuit of the hydraulic brake, this is used as an interlocking mechanism 8, and the sliding member 64 is interlocked using this. Other points are given reference numerals corresponding to those in the previous embodiment in the drawings, and explanations of each part are omitted.

〔Effect of the invention〕

There is no known invention that solves the above problems of the present invention. Therefore, the problem of the present invention is novel, and the unique effect of the present invention is that it solves this novel problem and eliminates the problems of the prior art.

In other words, when a vehicle such as a two-wheeled motor vehicle leans forward on a downhill slope, the damping force of the rear wheel shock absorber is reduced, and the relative damping force of the rear wheel hydraulic shock absorber during this running is adjusted. By compensating for this increase, it is possible to prevent the deterioration of riding comfort caused by the relative stiffness of the shock absorber (decreased shock absorbing performance), and furthermore to prevent pitching due to a decrease in the damping effect. The correlation between the rate and the increase in braking force can be compensated with high precision by controlling the rate of increase in the opening of the variable orifice, and therefore the damping force can be controlled just enough to match the increase in braking force. can do.

Furthermore, in order to utilize the pressure difference between the center chamber and the end chambers due to the base valve provided in the cylinder head of the hydraulic shock absorber, the present invention includes a variable orifice attached to the outer surface of the cylinder head, and a cylindrical shape forming the variable orifice. The opening degree of the variable orifice is mechanically adjusted by sliding the sliding member linearly, thereby reducing the damping force. Therefore, the application of the present invention requires additional mechanisms and structures. The increase in the additional mechanism and structure of each part is extremely small compared to when the variable orifice is installed separately from the cylinder or when the variable orifice is attached to the base valve of the reserve tank. Therefore, it is extremely effective in terms of saving installation space for equipment such as motorcycles that have little room for installation. Further, the present invention provides that the damping force reduction operation is performed in conjunction with the braking operation using the initial state of the variable orifice as a starting point, and the initial state of the variable orifice is used as the initial adjustment of the valve member constituting the variable orifice. Therefore, even if a phase error occurs between the operation of the brake pedal and the sliding member of the variable valve due to a discrepancy in the interlocking mechanism between the brake pedal and the sliding member of the variable valve, it can be adjusted by the initial adjustment without having to adjust the interlocking mechanism. This phase error can be easily corrected, and the damping force can be controlled with high precision over a long range of use, which is a great advantage.

[Brief explanation of drawings]

Fig. 1 is a front view of an embodiment in which the present invention is applied to a motorcycle, Fig. 2 is a sectional view of the rear wheel hydraulic shock absorber of Fig. 1, Fig. 3 is an enlarged view of the main parts of Fig. 2, FIG. 4 is an explanatory diagram of main parts of another embodiment. 1... Frame, 2... Rear frame, 5...
Hydraulic shock absorber, 6... Variable orifice, 7... Brake pedal, 8... Interlocking mechanism, 53... Cylinder, 56... Reserve tank, 59... Base valve, 61, 62... Communication port, 63... Orifice chamber, 64...Sliding member, 64b...Orifice valve seat, 64c...Return spring, 65...Valve member, A
...Central chamber, B...end chamber, S...orifice.

Claims (1)

[Claims] 1. A rear arm holding a rear wheel is pivotally supported on a frame, a buffer spring and a hydraulic shock absorber are interposed between the rear arm and the frame, and a piston having a damping force of the hydraulic shock absorber is provided. A base valve having a fixed orifice on the cylinder head side of the fitted cylinder and increasing the damping pressure during compression operation is installed inside the fitted cylinder, and the base valve divides the inside of the cylinder into a center chamber and an end chamber, and the end chamber is divided into a central chamber and an end chamber. In the case where the chamber is filled with high-pressure gas or communicated with the oil chamber of the reserve tank, the variable orifice chamber having a communication port communicating with the central chamber in the cylinder and a communication port communicating with the end chamber is connected to the hydraulic buffer. A cylindrical sliding member attached to the outside of the container and having an orifice valve seat is fitted into the variable orifice chamber, and the sliding member is urged by a spring to return in a direction that reduces the opening cross-sectional area of the orifice. Then, by interlocking the sliding member with the brake pedal,
The sliding member is slid against the return spring by actuation of the brake pedal, and the valve member facing the orifice valve seat of the sliding member is moved into the orifice chamber so that its position can be freely adjusted in the axial direction. A rear wheel suspension system for a two-wheeled motor vehicle or the like, wherein the rear wheel suspension device for a two-wheeled motor vehicle or the like is fixed, and the strength of throttling by the orifice is adjusted by adjusting the axial position of the valve member.