JPH03193548A - Antilock braking device for automobile - Google Patents

Abstract

PURPOSE:To enable it to use a small-sized modulator irrespective of a vacuum servo type brake system by installing a controller which opening an exhaust valve together with the closing of a feed valve at time of wheel-lock detection and operating a hydraulic control valve for its closing. CONSTITUTION:When a wheel tries to be locked by braling or a lock is detected by output of a speed sensor 18, an operating signal is outputted from a controller 19. If so, a feed valve 16 is closed while an exhaust valve 17 is opened instead, so that internal pressure in an air chamber 15 is lowered up to the extent of atmospheric pressure, and pressing force to the left of a piston 9 is decreased. Consequently, the piston 9 and a plunger 26 are moved to the right, and since push and open of a valve 24 by a pin 27 is interrupted, the valve 24 is seated on a valve seat 23 by dint of energizing force of a spring 25, whereby interconnection between a hydraulic inlet 21 and an outlet 22 is interrupted. In addition, the plunger 26 moves to the right, increasing the extent of capacity in a hydraulic chamber 28, so that internal pressure in the hydraulic chamber 23 being connected to the outlet 22 goes down, through which supplying hydraulic pressure for a wheel cylinder is compensated for decrement, thus a wheel lock is prevented from occurring.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an anti-lock brake system for an automobile, and specifically relates to an anti-lock brake system for an automobile equipped with a vacuum servo type brake system using a vacuum booster. It is.

<Prior Art> In order to improve the braking performance of an automobile service brake, an anti-lock brake device as shown in FIG. 3, for example, has conventionally been used. In this anti-lock brake system, air discharged from a near compressor a and stored in an air tank b is supplied to a brake booster e via a brake valve d operated by a brake pedal C. When air is supplied to the brake booster e, the oil supplied from the oil reservoir f to the brake booster e is pressurized, and the hydraulic pressure (brake pressure) responsive to the pressure of the air output from the brake valve d increases. This hydraulic pressure is output from the brake booster e, and is supplied to the cylinder of the wheel brake i via a hydraulic pressure control valve provided in the modulator g to perform the desired braking action.

Furthermore, the wheels are locked based on the output of the rotation sensor j that detects the rotation of the wheels (this is a state in which the deceleration of the rotational speed of the wheels becomes greater than the deceleration during normal deceleration operation and the wheels are about to stop rotating). The same applies hereinafter) is detected, a control signal is supplied from the controller k to the control valve k of the modulator g. Then, the air supply passage leading from the brake valve d to the air chamber of the control cylinder provided in the modulator g is closed, and the exhaust passage that opens the air chamber of the control cylinder to the atmosphere is opened. Therefore, when a wheel lock is detected, the internal pressure in the air chamber of the control cylinder of the modulator g decreases and the hydraulic pressure control valve is closed.
The hydraulic pressure (brake hydraulic pressure) supplied to the cylinder of the wheel brake i is reduced, and locking of the wheels is prevented (see Japanese Patent Publication No. 5G-7236, etc.).

<Problem to be solved by the invention> Since the conventional anti-lock brake device configured as described above uses air with a large pressure difference from atmospheric pressure, it can be directly applied to a vacuum servo type brake system. If it is applicable to an anti-lock brake system, it is necessary to increase the size of the control cylinder of the insulator to ensure the operating force of the hydraulic control valve, but it is controlled using a vacuum with a small differential pressure from atmospheric pressure. This control cylinder cannot be highly responsive due to the need to actuate the cylinder. Also, if the control cylinder is controlled by hydraulic pressure in order to increase its responsiveness and downsize it, the device becomes complicated because it is necessary to provide an oil pump, an accumulator, a reservoir, etc. There is also the problem that it becomes expensive.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an anti-lock brake device that can use a small modulator even though it is a vacuum servo type brake system.

<Means for Solving the Problems> In order to achieve the above object, the present invention includes a master cylinder that outputs hydraulic pressure in response to the amount of depression of the brake pedal, and a master cylinder that outputs hydraulic pressure in response to the amount of depression of the brake pedal, and a wheel pump that increases the output hydraulic pressure of the master cylinder. In an automobile equipped with a vacuum booster that supplies a vacuum booster to a cylinder, a modulator equipped with a hydraulic pressure control valve that opens and closes a hydraulic passage from the vacuum booster to a wheel cylinder, and a control cylinder that opens and closes the hydraulic pressure control valve is provided. There is. Further, a normally open air supply valve is provided in an air supply passage that connects the air chamber of the control cylinder of the modulator and the air tank, and a normally closed exhaust valve is provided in an exhaust passage that opens the air chamber to the atmosphere. The present invention is characterized in that a controller is provided that closes the air supply valve, opens the exhaust valve, and closes the hydraulic pressure control valve when a wheel lock is detected.

(Operation) In the anti-lock brake system for an automobile configured as described above, when the brake pedal is depressed, hydraulic pressure is supplied from the master cylinder to the vacuum booster in response to the depression stroke.

The vacuum booster increases the supplied hydraulic pressure and outputs it, and this hydraulic pressure is supplied to the wheel cylinder (hydraulic cylinder of the wheel brake) via the hydraulic pressure control valve of the modulator, so that braking force is obtained.

When supplying such hydraulic pressure, in a normal state where wheel lock is not detected, the air supply valve is opened and the exhaust valve is closed based on the output from the controller. Therefore,
In this case, the air in the air tank is supplied to the air chamber of the modulator's control cylinder through the air supply valve, so
The internal pressure of this air chamber is high and the hydraulic pressure control valve is opened. For this reason, the hydraulic pressure output from the vacuum booster passes through the hydraulic pressure control valve without being reduced and is supplied to the wheel brakes as is, so it responds to the force (stroke) of the brake pedal. braking force.

On the other hand, if the wheels lock when the brakes are applied, such as when driving on a low-friction road, the air supply valve installed in the air supply passage is closed based on the output signal from the controller. Since the exhaust valve installed in the exhaust passage is opened, the internal pressure in the air chamber of the control cylinder drops to atmospheric pressure. Then, the hydraulic pressure control valve of the modulator closes to cut off the increase in hydraulic pressure in the wheel cylinder, and the volume of the hydraulic pressure control valve increases to reduce the hydraulic pressure on the wheel cylinder side. The hydraulic pressure of the brake is corrected to reduce the pressure, and the braking force of the wheel brake is corrected to reduce, thereby preventing the wheels from locking.

After the wheels are prevented from locking in this way, the air intake valve is opened and the exhaust valve is closed based on the output from the rotation sensor, so air from the air tank is supplied to the air chamber of the control cylinder. be done. Therefore, the hydraulic pressure control valve is returned to its open position, and the correction for reducing the hydraulic pressure supplied to the wheel cylinders is interrupted to increase the braking force. Thereafter, the air supply valve and the exhaust valve are similarly controlled to open and close based on the rotational state of the wheels, thereby controlling the increase/decrease of the internal pressure in the air chamber of the control cylinder, and the hydraulic pressure ( The system gradually stops the vehicle by adjusting the brake fluid pressure (brake fluid pressure).

On the other hand, when the brake pedal is released, the output pressure of the master cylinder decreases, which causes the fluid pressure output from the vacuum booster to decrease. The hydraulic pressure (braking force) also decreases.

Note that when such a modulator operates, the air in the air tank is consumed only when the wheels are locked, so the amount of air consumed is extremely small. Therefore, the capacity of the air tank and near compressor can be reduced, and since the modulator is operated using air pressure that has a larger pressure difference from atmospheric pressure than vacuum, this modulator can also be made smaller and lighter.

<Example> An example of the present invention will be described below in detail based on FIGS. 1 and 2.

FIG. 1 is a configuration diagram showing an outline of an anti-lock brake system for an automobile according to the present invention, in which a vacuum supply port of a vacuum booster 2 is connected to a vacuum tank 1 in which vacuum is accumulated as an engine (not shown) is operated. At the same time, by connecting the output port of the master cylinder 3 to the hydraulic pressure supply port of the vacuum booster 2, the hydraulic pressure output from the master cylinder 3 according to the depression stroke (!depression force) of the brake pedal 4 is applied to the vacuum booster 2. 2 increases the pressure and outputs it.

By connecting the hydraulic pressure cylinder (hereinafter referred to as a wheel cylinder) of the wheel brake 7 to the hydraulic pressure output port of the vacuum booster 2 via the hydraulic pressure control valve 6 of the modulator 5, the leakage liquid output from the vacuum booster 2 can be controlled. Pressure is supplied to the wheel cylinder to operate the wheel brake 7. 8 is an oil reservoir provided in the master cylinder 3.

The modulator 5 is constructed as shown in FIG. 2, and includes an air supply passage 12 and an exhaust passage 13 in a housing 11 that covers the end face of a control cylinder lO in which a piston 9 connected to the hydraulic pressure control valve 6 is fitted. and. Then, while connecting one end of the air supply passage 12 to the air tank 14,
The other end of this air supply passage 12 is connected to the air chamber 1 of the control cylinder 10.
5, and this air chamber 15 is connected to outside air via the exhaust passage 13.

Further, the air supply passage 12 is provided with an air supply valve 16 which is an electromagnetic check valve.
A controller 19 is provided with an exhaust valve 17 which is also an electromagnetic check valve in the exhaust passage 13, and to which the output of a rotation sensor 18 that outputs a signal corresponding to the rotational speed of the wheels is supplied as a control signal. By connecting the air supply valve 16 and the exhaust valve 17 to the output terminals of the controller 19, the air supply valve 16 and the exhaust valve 17 are controlled to open and close using the controller 19.

A near compressor 20 supplies air to the air tank 4, and is driven as the engine operates.

On the other hand, as shown in FIG. 2, the hydraulic pressure control valve 6 is provided with a hydraulic inlet 21 connected to the hydraulic outlet of the vacuum booster 2 and a hydraulic outlet 22 connected to the wheel cylinder. , the hydraulic pressure inlet 21 and the hydraulic pressure outlet 22 are communicated with each other via a passage provided in a valve seat 23 provided between the two. Further, 24 is a valve disposed on the hydraulic pressure inlet 21 side of the valve seat 23, 25 is a spring that holds this valve 24 seated on the valve seat 23 and closes the passage provided in this valve seat 23, and 26 is a valve. It is a plunger that faces the valve 24 with a seat 23 in between, and the tip of a bottle 27 fixed to the end face of the plunger is made to face the end face of the valve 24 from a passage provided in the valve seat 23. Further, by connecting the plunger 26 and the piston 9, the valve 24 is opened and closed depending on the balance between the internal pressure of the control cylinder 10 and the internal pressure of the hydraulic pressure chamber 28 acting on the end surface of the plunger 26. Communication is cut off between the hydraulic pressure inlet 25 and the hydraulic pressure outlet 22,
The degree of pressure reduction (correction amount) of the hydraulic pressure supplied to the wheel cylinders is adjusted to increase or decrease by using the increase or decrease in the volume of the hydraulic chamber 2B corresponding to the amount of movement a of the plunger 26 and the piston 9.

In the anti-lock brake system for an automobile configured as described above, when the brake pedal 5 is depressed, a hydraulic pressure responsive to the depression force (stroke) of the brake pedal 5 at this time is outputted from the master cylinder 3.

At this time, during braking in a normal state where the wheels do not lock, the air supply valve 16 is opened by the inactivation signal output from the controller 19, and the exhaust valve 17 is closed, so air is supplied from the air tank 14. Since the air is supplied to the air chamber 15 of the control cylinder 10 through the valve 16, the internal pressure of the air chamber 15 of the control cylinder 10 becomes higher than atmospheric pressure, and the force that presses the piston 9 to the left in FIG. The force is greater than the force output from the booster 2 and pushing the plunger 26 to the right in the figure. Then, the piston 9 and plunger 26 move to the left of the illustrated position and move the bottle 27 in the same direction, so the valve 24 is opened against the spring 25 and the hydraulic pressure being supplied to the hydraulic inlet 25 is reduced. is output as is to the hydraulic pressure outlet 22.

Therefore, when the wheels are not locked, the hydraulic pressure output from the vacuum booster 2 is supplied to the wheel cylinders to perform the desired braking action, as in the case of a brake system that does not include an anti-lock brake system.

On the other hand, such braking causes the wheels to try to lock;
Alternatively, when locking is detected based on the output of the rotation sensor 18, the controller 19 outputs an actuation signal. Then, since the air supply valve 16 is closed and the exhaust valve 17 is opened at the same time, the internal pressure of the air chamber 15 decreases to atmospheric pressure, and the force pushing the piston 9 to the left in the figure decreases. For this purpose, the piston 15 and the plunger 26 move to the right in the figure and interrupt the push-opening of the valve 24 by the bottle 27, so that the valve 24 is seated on the valve seat 23 by the biasing force of the spring 25, and the hydraulic inlet 25 and the valve 24 are seated. Hydraulic outlet 22
Cut off communication with. Furthermore, since the plunger 26 moves to the right in the figure and increases the volume of the hydraulic chamber 28, the internal pressure of the hydraulic chamber 23 connected to the hydraulic pressure outlet 22 decreases, causing the fluid supplied to the wheel cylinder to decrease. Avoid wheel lock by correcting the pressure.

Furthermore, when the wheels are prevented from locking in this way, the controller 19 outputs a deactivation signal, opens the air intake valve 16, and closes the exhaust valve 17, so that the air chamber 1 is closed.
5 rises again, the valve 24 is opened to increase the fluid pressure supplied to the wheel cylinder, and thereafter, the air supply valve 16 and the exhaust valve 17 are similarly controlled to open and close to increase the fluid pressure supplied to the wheel cylinder. It optimally controls pressure and performs the same anti-lock function as conventional anti-lock brake devices.

In addition, when the air supply valve 16 and the exhaust valve 17 are incorporated into the air supply passage 12 and the exhaust passage 13 of the housing 11 as in the embodiment, the entire device can be made smaller and lighter, and an anti-lock brake device can be added. This is convenient because it reduces the number of piping steps required.

In addition, as shown by the two-dot chain line in FIG.
If the vacuum passage 30 is provided to introduce negative pressure to the air chamber 15, the pressure difference between both sides of the piston 9 can be made larger when air is supplied to the air chamber 15.
It is also possible to downsize. Furthermore, in the Fruit Gohan, both the air supply valve 16 and the exhaust valve 17 are configured with electromagnetic check valves to ensure operational responsiveness, but the function of opening and closing the air supply passage 12 and the exhaust passage 13 is not included. The specific configurations of the air supply valve 16 and the exhaust valve 17 are arbitrary as long as they have the same.

<Effects of the Invention> As is clear from the above description, according to the present invention, air is supplied to the modulator that can increase the pressure difference from atmospheric pressure, despite the vacuum servo brake system. Therefore, the modulator can be made smaller and lighter. Furthermore, since air is only consumed when brake lock is detected, the capacity of the near compressor, air tank, etc. can be reduced in size.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an anti-lock brake system for an automobile according to the present invention, FIG. 2 is a cross-sectional view showing the internal structure of a modulator, and FIG. 3 is a block diagram schematically showing a conventional example.

Claims (1)

[Claims] (1) Controls a master cylinder that outputs hydraulic pressure in response to the amount of depression of the brake pedal, a vacuum booster that increases the hydraulic pressure output from the master cylinder, and a hydraulic passage from the vacuum booster to the wheel cylinder. a modulator provided with a hydraulic pressure control valve and a control cylinder for controlling the hydraulic pressure control valve; a normally open air supply valve interposed in an air supply passage connecting an air chamber of the control cylinder and an air tank; A normally closed exhaust valve installed in an exhaust passage that opens the air chamber of the cylinder to the atmosphere, and a normally closed exhaust valve installed in an exhaust passage that opens the air chamber of the cylinder to the atmosphere, and a normally closed exhaust valve that closes the air supply valve and opens the exhaust valve when a wheel lock is detected. An anti-lock brake system for an automobile, comprising a controller that closes a control valve and corrects the hydraulic pressure supplied to a wheel cylinder by reducing the pressure.