JPH065277Y2 - Brake fluid pressure control device - Google Patents

Description

[Detailed Description of the Invention] Industrial field of application The present invention is capable of individually controlling the brake fluid pressure supplied to each wheel, and equipped with a proportioning valve in the pipeline of the brake fluid to the left and right rear wheels. The present invention relates to a brake fluid pressure control device.

2. Description of the Related Art Generally, in a hydraulic brake device, the load on the rear wheels is reduced compared to the load on the front wheels during braking, and the rear wheels tend to lock easily. Rear wheel brake input controls have been used which aim to match the ratio. A proportioning valve is normally used as an example of the input control device, but when the brake fluid pressure becomes equal to or higher than a certain fluid pressure, which is the operation start point, the proportioning valve will increase the rear wheel side fluid pressure thereafter. Is reduced at a constant ratio with respect to the front wheels.

In addition to the above, a linkage type load sensing proportion valve that changes the brake fluid pressure at the operation start point by detecting the change in vehicle weight from the dimensional change of the spring installed between the sprung and unsprung, or the vehicle is constant A non-linkage type load sensing proportion valve, etc. that forms a pressure chamber that is closed by the operation of the ball valve when it reaches the deceleration of the above, and uses this pressure chamber to adjust the spring load for setting the operation start point. It has been known.

There is also known a means for adjusting the operation starting point of the brake fluid by incorporating a proportioning valve in the master cylinder, and the valves are arranged in series in order to be applied particularly to an X-type two-system brake pipe. Dual proportioning valve structures are also used.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the case of such a conventional brake fluid pressure control device, there is a problem in that when the vehicle brakes at high speed, the rear wheels cannot always obtain the optimum pressure reducing characteristics. . That is, in general, when the vehicle is traveling at an extremely high speed, the influence of the aerodynamic characteristics, which is effective when the vehicle speed is squared, increases.
Moreover, the nose dive phenomenon during braking significantly changes the aerodynamic characteristics and increases the downforce of the front wheels, while the downforce of the rear wheels is not so great.
Therefore, there is a phenomenon that the load on the rear wheel side becomes relatively low. On the other hand, the proportioning valve as the input control device for the rear wheel brakes described above does not take into consideration the influence of the aerodynamic characteristics due to the high speed running, and therefore cannot be sufficiently dealt with, particularly during high speed braking of the vehicle. In addition, there is a problem that the brake fluid pressure on the rear wheel side becomes high and the vehicle body may become unstable during high-speed braking.

Therefore, the present invention solves the problem of such a conventional brake fluid pressure control device, and makes the braking fluid pressure different between the front and rear wheels at the time of high-speed braking of the vehicle by a simple configuration. An object of the present invention is to provide a brake fluid pressure control device capable of improving the stability of the vehicle body at the time.

Means for Solving the Problems In order to achieve the above object, the present invention is capable of individually controlling the brake fluid pressure supplied from a master cylinder to each wheel, and a pipe for supplying the brake fluid to the left and right rear wheels. In a brake fluid pressure control device equipped with a proportioning valve for reducing the rear wheel brake fluid pressure with respect to the front wheel brake fluid pressure in the middle of the path, in the pipeline located on the input side or the output side of the proportioning valve, When the vehicle is running below the predetermined vehicle speed, it has no effect, and when the vehicle speeds up above the predetermined vehicle speed, the vehicle speed signal acts to reduce the brake fluid pressure in the pipeline.
The brake fluid pressure control device is equipped with a pressure reducing valve that double reduces the brake fluid pressure supplied to the rear wheels together with the proportioning valve.

According to such a configuration, when the vehicle is traveling at a speed lower than the predetermined vehicle speed, the pressure reducing valve does not operate at all, and therefore the rear wheels are reduced in pressure based on the pressure reducing characteristic of the normal proportioning valve. The brake fluid pressure is supplied. Next, when the vehicle speed of the vehicle increases above the predetermined vehicle speed, the pressure reducing valve mounted on the input side or the output side of the proportioning valve starts operating by this vehicle speed signal, and the pressure reducing valve sets a predetermined value. The pressure of the brake fluid flowing in the pipe is reduced based on the pressure reducing characteristic of. Therefore, the brake fluid pressure supplied to the rear wheels is subjected to a double pressure reducing action by the pressure reducing valve and the normal proportioning valve, and the pressure reducing action by the pressure reducing valve is increased during high speed traveling, so that the vehicle travels at high speed. It is possible to obtain the effect that the stability of the vehicle body can be improved with respect to the braking operation at a certain time.

Embodiments Various embodiments of a brake fluid pressure control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a basic embodiment of the present invention,
In the figure, 1 is a brake pedal, 2 is a master cylinder, 3 is a right front wheel, 4 is a left front wheel, 5 is a right rear wheel, and 6 is a left rear wheel. The master cylinder 2 has two pressure chambers 2a and 2b, two brake fluid pipe systems are led out from the two pressure chambers 2a and 2b, and one pipe line 11 is a pipe line. 11a, 11b, the pipe line 11a is connected to the wheel cylinder 3a of the right front wheel 3, the pipe line 11b of the left rear wheel 6 via an electromagnetic pressure reducing valve 17 and proportioning valve 15 described later. Wheel cylinder 6a
Are linked to. Further, the conduit 12 on the other side of the master cylinder 2 is branched into conduits 12a and 12b, and the conduit 12a
Is connected to the wheel cylinder 4a of the left front wheel 4,
The pipe line 12b is connected to the wheel cylinder 5a of the right rear wheel 5 via an electromagnetic pressure reducing valve 18 and a proportioning valve 16 described later. That is, the above embodiment shows an example in which the pipeline of the brake fluid is connected to the wheel cylinder of each wheel by using a means usually called X pipe.

A controller 20 receives a vehicle speed signal V from a vehicle speed sensor (not shown) and transmits a control signal to a solenoid 17a of the electromagnetic pressure reducing valve 17 and a solenoid 18a of the electromagnetic pressure reducing valve 18 via a signal line 21. ing.

The electromagnetic pressure reducing valves 17 and 18 are mounted in the midway portions of the conduits 11b and 12b located on the input side of the proportioning valves 15 and 16, respectively, but the present invention is limited to the above structure. Instead, the electromagnetic pressure reducing valves 17 and 18 may be attached to the conduits located on the output side of the proportioning valves 15 and 16.

The operation of the basic embodiment of the present invention having such a configuration will be described below. That is, when the vehicle is traveling at a speed lower than a predetermined vehicle speed, the electromagnetic pressure reducing valves 17 and 18 do not act at all, and therefore the proportioning valves 15 and 16 are applied to the rear wheels 5 and 6.
The brake fluid pressure reduced based on the pressure reduction characteristics of is supplied.

Next, when the vehicle speed of the vehicle increases above a predetermined vehicle speed, the electromagnetic pressure reducing valves 17 and 18 start operating based on the control signal output from the controller 20, and the electromagnetic pressure reducing valve 1
The hydraulic pressure of the brake fluid flowing in the pipelines 11b and 12b is reduced based on the predetermined pressure reducing characteristics set in advance by the valves 7 and 18. Therefore, the brake fluid pressure supplied to the rear wheels 5, 6 is subjected to a double pressure reducing action by the electromagnetic pressure reducing valves 17, 18 and the proportioning valves 15, 16 and, at the same time, the electromagnetic pressure reducing valves 17, 18 are operated at high speed. As a result, the brake fluid pressure supplied to the rear wheels 5, 6 is further reduced, the high-speed braking performance of the vehicle is improved, and the stability of the vehicle body can be improved.

The above operation will be described more specifically. That is, FIG. 2 shows the input hydraulic pressure P to the proportioning valves 15 and 16 described above.
₁ is a graph showing the correlation between the output hydraulic pressure P ₂ and FIG. 3, and FIG. 3 shows the input hydraulic pressure L ₁ to the electromagnetic pressure reducing valves 17 and 18 and the output hydraulic pressure L ₂
That is, it is a graph showing the correlation of the input hydraulic pressure P ₁ to the proportioning valves 15 and 16. Further, FIG. 4 shows the output hydraulic pressure L of the electromagnetic pressure reducing valves 17, 18 with respect to the current i supplied to the solenoids 17a, 18a of the electromagnetic pressure reducing valves 17, 18.
The characteristic example of the maximum value of max is shown.

Therefore, as shown in FIG. 4, when the current i is 0, the electromagnetic pressure reducing valves 17 and 18 are in the released state, and therefore the brake fluid pressure supplied to the left and right rear wheels 5 and 6 is It is determined only by the pressure reducing characteristics of the proportioning valves 15 and 16.

Next, when the current i changes from 0 to i ', the maximum value of the output hydraulic pressure from the electromagnetic pressure reducing valves 17 and 18 is also L'as shown in FIG.
As a result, the input / output characteristics of the electromagnetic pressure reducing valves 17 and 18 change from the graph A shown in FIG. 3 to the graph B shown in FIG. That is, the graph A shows the case where the current value i is 0, and the input hydraulic pressure L ₁ and the output hydraulic pressure L ₁ of the electromagnetic pressure reducing valves 17, 18 are L.
_Although it has a direct proportional relationship with ₂ , when the current value i = i 'flows, the maximum value of the output hydraulic pressure is reduced to L'max. When the input hydraulic pressure L ₁ of the electromagnetic pressure reducing valves 17 and 18 is greater than or equal to L′ max, the output hydraulic pressure L′ max is input to the proportioning valves 15 and 16. Therefore, the output hydraulic pressure of the proportioning valves 15 and 16 is increased. 2, the output fluid pressure P ₂ ′ under normal conditions is reduced to P ₂ ″. As described above, the solenoid 1 of the electromagnetic pressure reducing valves 17 and 18 is reduced.
The output hydraulic pressure from the proportioning valves 15 and 16 is changed to the second value based on the change of the current value i flowing through 7a and 18a.
Although the pressure can be reduced as shown in the graph of the figure, the present invention is characterized in that the current i is set as a function of the vehicle speed.

FIG. 5 is a correlation diagram of the vehicle speed V and the current i pre-programmed in the controller 20. In the figure, V ₀ is the vehicle speed at which the aerodynamic characteristics of the vehicle at the time of running start, and the vehicle speed V ′
Is a vehicle speed higher than the vehicle speed V ₀ , a current value i ′ is set to flow from the controller 20 to the electromagnetic pressure reducing valves 17 and 18. Therefore, according to FIG. 5, from the vehicle speed 0 to reach the V ₀ is the current value 0
Therefore, when the vehicle speed becomes V ₀ or higher, the current value i ′ flows while increasing substantially quadratically. That is, as described above, since the aerodynamic characteristics during high-speed running are effective when the vehicle speed is squared, it is necessary to increase the value of the current supplied to the solenoids 17a and 18a of the electromagnetic pressure reducing valves 17 and 18 by a quadratic function.

It is even more effective to set the vehicle speed V ₀ so as to match the vehicle speed V _{A at} which the aerodynamic variable means, for example, the auto spoiler starts to operate. The above-mentioned auto spoiler refers to one that automatically switches from a non-operating state to an operating state when the vehicle speed exceeds a certain vehicle speed.

Figure 6 shows an example of the magnitude of the current value i as a control signal outputted from the controller 20, not only the vehicle speed V, the was to be able to control in conjunction with other electrical signals S _W ing. As the electric signal S _W and can take from the wiper switch for example, when the wiper switch is on, the magnitude of the current i with respect to the vehicle speed V 7
The control is performed so as to rise from the vehicle speed V _0a as shown in the graph C in the figure, and is controlled so as to rise from the vehicle speed V _0b as shown in the graph D in the figure when the wiper switch is off. Further, the line of the graph C can be further divided according to the strength of the position of the wiper switch.

With such a configuration, the current i flowing through the electromagnetic pressure reducing valves 17 and 18 can be controlled not only by the vehicle speed but also by the road surface condition caused by the presence or absence of rainfall, and the rear wheels 5, 6 on the low friction road surface. There is an advantage that the lock of the device can be prevented and the applicability of the device of the present invention can be expanded.

Incidentally, the embodiment of the present invention shows an example in which the two lines of the brake fluid are connected to the wheel cylinders of the respective wheels by means of means usually called X piping as described above. The present invention is not limited to such a piping example, and can also be applied to a piping system in which two lines of brake fluid lines are connected to the wheel cylinders of the left and right wheels, which is usually called I pipe.

Further, as the proportioning valves 15 and 16, any known type can be used, and linkage type, non-linkage type, dual proportion structure and the like can be applied.

Effects of the Invention As described in detail above, according to the brake fluid pressure control device of the present invention, the brake fluid pressure supplied from the master cylinder to each wheel can be individually controlled, and the brake fluid can be applied to the left and right rear wheels. In a brake fluid pressure control device equipped with a proportioning valve that reduces the rear wheel brake fluid pressure with respect to the front wheel brake fluid pressure in the middle of the pipeline that supplies the fluid, it is located at the input side or the output side of the proportioning valve. There is no effect on the pipeline when the vehicle is running below the prescribed vehicle speed, and when the vehicle speed increases above the prescribed vehicle speed, this vehicle speed signal reduces the brake fluid pressure in the pipeline. Then, the brake fluid pressure control device is equipped with a pressure reducing valve that double reduces the brake fluid pressure supplied to the rear wheels together with the proportioning valve. As a result, the following action depression is brought about.
That is, when the vehicle is running at a speed lower than a predetermined vehicle speed, the pressure reducing valve has no effect, and therefore the rear wheel is supplied with the brake fluid pressure reduced based on the pressure reducing characteristic of the normal proportioning valve. On the other hand, when the vehicle speed of the vehicle increases above a predetermined value, the vehicle speed signal causes the pressure reducing valve to reduce the hydraulic pressure of the brake fluid flowing in the pipe line based on a predetermined pressure reducing characteristic set in advance. The brake fluid pressure supplied to is subjected to a double pressure reducing action by the pressure reducing valve and the normal proportioning valve, and the pressure reducing effect by the pressure reducing valve can be enhanced during high speed traveling. Therefore, it is possible to cancel the influence of the aerodynamic characteristics which is effective when the vehicle speed is squared, by the pressure reducing valve, and it is possible to improve the stability of the vehicle body against the braking operation during the high speed braking of the vehicle. Be brought. Further, the present invention is advantageous in terms of assembling because the structure itself is simple.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic embodiment of a brake fluid pressure control device according to the present invention, FIG. 2 is a graph showing the input / output characteristics of a proportioning valve, and FIG. 3 is the input / output characteristics of a pressure reducing valve. Graph, FIG. 4 is a graph showing current-hydraulic pressure characteristics of the pressure reducing valve, FIG. 5 is a graph showing correlation between vehicle speed and current used in the present invention, and FIG. 6 is a schematic view showing another embodiment of the present invention. FIG. 7 is a graph showing a vehicle speed-current characteristic in the other embodiment. 1 …… Brake pedal, 2 …… Master cylinder, 3 ………… Right front wheel, 4 …… Left front wheel, 5 …… Right rear wheel, 6 …… Left rear wheel, 15,16 …… Proportioning valve, 17 , 18 ... electromagnetic pressure reducing valve, 20 ... controller,

Claims (1)

[Scope of utility model registration request] 1. A brake fluid pressure supplied from a master cylinder to each wheel is individually controllable, and a rear wheel with respect to a front wheel brake fluid pressure is provided in a middle portion of a pipeline for supplying brake fluid to the left and right rear wheels. In a brake fluid pressure control device equipped with a proportioning valve for reducing the brake fluid pressure, in the pipeline located on the input side or the output side of the proportioning valve, there is no action when the vehicle is traveling below a predetermined vehicle speed. When the vehicle speed is increased to a predetermined speed or more, the vehicle speed signal acts to reduce the brake hydraulic pressure in the pipeline, and the brake hydraulic pressure supplied to the rear wheels is increased together with the proportioning valve. A brake fluid pressure control device, which is equipped with a pressure reducing valve for double pressure reduction.