JPH0331049A - Antilock brake device for automobile - Google Patents

Abstract

PURPOSE:To suppress air consumption by integrally providing a supply air passage, which interposes an air supply valve, return passage, which bypasses the air supply valve and interposes a holding valve, and an exhaust passage, which interposes an exhaust valve, in a modulator provided with a hydraulic control valve for controlling a pressure of oil supplied to a wheel cylinder. CONSTITUTION:A brake booster 4 is connected to an air tank 2, connected to a compressor 1, through a brake valve 3, and wheel cylinders 8 are connected to pressure oil output port of the brake booster 4 through hydraulic control valves 7 of modulators 6. Also, air supply ports of the modulators 6 are connected to the brake valve 3 through air pipes. Each modulator 6 is constituted such that in a housing 12 for coating the end face of a control cylinder 11 fitted with a piston 10 connected to the hydraulic control valve 7, a supply air passage 13 and an exhaust passage 14 are provided to respectively interpose an air supply valve 16 in the supply air passage 13 and an exhaust valve 17 in the exhaust passage 14 while a return passage 20, which bypasses the air supply valve 16, is provided to interpose a holding valve 21 in the halfway.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an anti-lock brake system for automobiles.
More specifically, the present invention relates to an anti-lock brake device for air-over braking using a brake booster and a modulator.

<Prior Art> In order to improve the braking performance of an automobile's service brake, an anti-lock brake device as shown in FIG. 3, for example, has been used. To explain this anti-lock brake device, air discharged from a 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 oil pressure (brake pressure) responds to the pressure of the air output from the brake valve d.
is output from this brake booster e, and is applied to the wheel brake i via the hydraulic control valve provided in the modulator g.
is supplied to the cylinder for the desired braking action.

Further, the rotation of the wheel is detected by a rotation sensor j, and when the rotation of the wheel has stopped or is about to stop based on the output of the rotation sensor j, that is, when the lock of the wheel is detected, the controller k sends a signal to the modulator. A control signal is supplied to control valve l of g. Then, the air supply passage from the brake valve d to the air chamber of the control cylinder provided in the modulator g is closed, and the exhaust passage is opened. When the internal pressure of the air chamber decreases in this way, the hydraulic pressure (brake hydraulic pressure) supplied to the cylinder of the wheel brake i decreases, thereby preventing the wheels from locking (see Japanese Patent Publication No. 7236/1983). ).

<Problems to be Solved by the Invention> In the conventional anti-lock brake device having 41 units as described above, a modulator g is provided for each wheel (wheel brake), and when the brake pedal C is released, the brake booster is activated. e and the air in the modulator g will be exhausted from the brake valve d. For this reason, by employing an anti-lock brake device, the amount of air consumed increases, and accordingly, it becomes necessary to increase the capacity of the air tank b. Therefore, when a conventional anti-lock brake system with such a configuration is installed, the air tank of a normal brake system without an anti-lock brake system cannot be used as is, or as the capacity of the air tank increases, There was a problem in that the weight increased and, furthermore, the operation rate of the near compressor a increased, resulting in an increase in power loss.

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 for an automobile that can suppress an increase in air consumption due to the adoption of an anti-lock brake device.

<Means for Solving the Problems> In order to achieve the above object, the present invention includes a brake booster that generates hydraulic pressure in response to air pressure output from a brake valve operated by a brake pedal, and a brake booster that generates hydraulic pressure in response to air pressure output from a brake valve operated by a brake pedal. An anti-lock brake system for an automobile comprising a hydraulic control valve that controls hydraulic pressure supplied to a wheel cylinder, and a modulator having a control cylinder to which air output from the brake valve is supplied, wherein the hydraulic pressure is supplied from the brake valve. An air supply passage for introducing air into the air chamber of the control cylinder, a return passage connected in parallel to the air supply passage, and an exhaust passage for connecting the air chamber to the atmosphere are formed in the housing of the modulator. Then, an air supply valve that closes the air supply passage when a wheel lock (referring to a state in which the wheel rotation has stopped or is about to stop; the same applies hereinafter) is detected, and an air supply valve that closes the air supply passage when a wheel lock is detected. An exhaust valve that sometimes opens the exhaust passage and a holding valve that closes the return passage when the air pressure output from the brake valve is below a predetermined value are provided, and these air supply valves, exhaust valves, and holding valves are provided. The present invention is characterized in that valves are incorporated in the air supply passage, the exhaust passage, and the return passage.

<Operation> In the anti-lock brake system for an automobile configured as described above, when the brake pedal is depressed, air pressure responsive to the depression stroke is supplied from the brake valve to the air chambers of the brake booster and the modulator. The brake booster outputs hydraulic pressure in response to the supplied air pressure, and this hydraulic pressure is supplied to the wheel cylinder (hydraulic cylinder of the wheel brake) via the hydraulic control valve of the modulator, so that braking force is obtained.

When supplying such hydraulic pressure, if the wheels are not in a locked state, the air supply valve is opened and the exhaust valve is closed based on the output from the rotation sensor.

Therefore, in this case, the air pressure output from the brake valve is supplied to the air chamber of the modulator's control cylinder via the air supply valve, so the internal pressure of this air chamber becomes high, and the brake booster outputs the air pressure. In order to supply the applied hydraulic pressure as it is to the wheel brakes without attenuation, a braking force responsive to the depression operation force (stroke) of the brake pedal can be obtained.

On the other hand, if the wheels lock when the brakes are applied, such as when driving on a low-friction road, this fact is detected (calculated) based on the output signal from the rotation sensor. Then, the air supply valve installed in the air supply passage is closed, and the exhaust valve installed in the exhaust passage is opened, so that the internal pressure of the air chamber decreases. Therefore, the hydraulic control valve of the modulator closes to stop the increase in the hydraulic pressure of the wheel cylinder, and the volume of the hydraulic chamber of the hydraulic control valve increases to compensate for the attenuation of the hydraulic pressure supplied from the brake booster to the wheel cylinder. The braking force of the wheel brake is reduced and corrected to prevent the wheels from locking.

After the wheels are prevented from locking in this way, the intake valve is opened and the exhaust valve is closed based on the output from the rotation sensor, so the internal pressure of the control cylinder rises again and the wheel cylinder The damping correction of the hydraulic pressure supplied to the brake system is interrupted to increase the braking force. Thereafter, the air supply valve and exhaust valve are controlled to open and close based on the rotational state of the wheels, the internal pressure of the air chamber is controlled to increase or decrease, and the hydraulic pressure (brake hydraulic pressure) is supplied to the wheel cylinders to prevent the wheels from locking.
The vehicle is gradually brought to a stop by increasing or decreasing the amount.

On the other hand, when the brake pedal is released, the air pressure output from the brake valve decreases, so the oil pressure output from the brake booster decreases.

Also, when the output pressure of the brake valve decreases in this way, the air in the air chamber of the control cylinder flows out through the return passage, so the air chamber decreases in synchronization with the decrease in the hydraulic pressure output from the brake booster. Internal pressure also decreases. For this reason, in the process of releasing the brake pedal, the output pressure of the brake booster decreases and the hydraulic pressure (braking force) supplied to the wheel cylinders also decreases.

When the air pressure output from the brake valve becomes lower than the set pressure of the holding valve, the holding valve closes to prevent the air from flowing out of the air chamber (maintaining the pressure). Therefore, even when the brake pedal is released, the air in the control cylinder (air chamber) of the modulator is not completely exhausted as in the conventional case, and the amount of air consumed is suppressed.

Furthermore, the housing of this modulator is equipped with a holding valve that suppresses air consumption, and an air supply valve and an exhaust valve that increase or decrease the internal pressure of the control cylinder to correct the increase or decrease of the hydraulic pressure supplied from the brake booster to the wheel cylinder. Since it is interposed in the provided air supply passage and exhaust passage, the entire device can be made smaller and the number of man-hours required for piping can be reduced.

<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. An air tank 2 is connected to a near compressor l driven by an engine (not shown), and a brake valve 3 is connected to the air tank 2. The air supply port of the brake booster 4 is connected to the brake booster 4. 5 is a brake pedal provided on the brake valve 3.

A hydraulic cylinder (hereinafter referred to as a wheel cylinder) of a wheel brake 8 is connected to the hydraulic output port of the brake booster 4 via a hydraulic control valve 7 of a modulator 6, so that the hydraulic pressure output from the brake booster 4 is transferred to the wheel cylinder. The wheel brakes 8 are actuated by supplying the brake fluid to the vehicle. 9 is an oil reservoir provided in the brake booster 4.

The brake valve 3 is connected to an air supply port of a modulator 6 via an air pipe. This modulator 6
is constructed as shown in FIG. 2, and includes a control cylinder 1 into which a piston 10 connected to the hydraulic control valve 7 is inserted.
An air supply passage 13 and an exhaust passage 14 are provided in a housing 12 that covers the end face of the housing 1.

Then, one end of the air supply passage 13 is connected to the air output port of the brake valve 3, and the other end of this air supply passage 13 is opened to the air chamber 15 of the control cylinder 11, and this air chamber 15 is connected to the outside air. They are connected via the exhaust passage 14.

Further, the air supply passage 13 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 14, and to which the output of a rotation sensor 18 that outputs a signal corresponding to the rotational speed of the wheel 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.

Furthermore, a return passage 20 that bypasses the air supply valve 16 is provided in the housing 12, and a holding valve 21 is interposed in this return passage 12.

The holding valve 21 has a valve seat 22 provided in the return passage 20, a valve 23 facing the valve seat 22 from the brake valve side, and a valve spring 24 that seats and holds the valve 23 on the valve seat 22. Consists of a stop valve.

25 is a hydraulic inlet of the hydraulic control valve 7, and 26 is a hydraulic outlet.The hydraulic inlet 25 is connected to the hydraulic output port of the brake booster 4, and the hydraulic outlet 26 is connected to the wheel cylinder. 27 is the valve of the hydraulic control valve 7, 28 is the valve seat, and 29 is the valve seat 2.
It is a plunger that passes through a passage provided at 8 and faces the valve 27, and its end face faces the tip of the bottle 3o fixed to the valve 27. Further, by connecting the plunger 29 and the piston 10, the valve 27 is opened and closed depending on the balance between the internal pressure of the control cylinder 11 and the hydraulic pressure acting on the end face of the plunger 29, thereby connecting the hydraulic pressure inlet 25 and the hydraulic pressure. Communication with the outlet 26 is cut off, and 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 31 corresponding to the amount of movement of the plunger 29 and the piston IO. I try to do that.

In the automobile anti-lock brake system configured as described above, when the brake pedal 5 is depressed to open the brake valve 3, the air pressure responsive to the depression force (stroke) of the brake pedal 5 at this time is output from the brake valve 3. be done.

At this time, during braking in a normal state in which the wheels do not lock, the air intake valve 16 is opened and the exhaust valve 17 is closed in response to the inactivation signal output from the controller 19. For this purpose, air output from the brake valve 3 when the brake pedal 5 is depressed is supplied to the brake booster 4 and also to the air chamber 15 of the control cylinder 11 via the air supply valve 16.

Therefore, the internal pressure of the air chamber 15 of the control cylinder 11 rises in accordance with the output of the brake valve 3, and the force that presses the piston lO to the left in FIG. The force is greater than the pressing force. Then, the piston 10 and plunger 29 move to the left of the illustrated position and move the bottle 30 in the same direction, so the valve 27 is opened and the hydraulic pressure being supplied to the hydraulic inlet 25 is directly output to the hydraulic outlet 26. Ru. Therefore, when the wheels are not locked, the hydraulic pressure output from the brake booster 4 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, and the force that presses the piston 10 to the left in the figure decreases. For this purpose, the piston 15 and the plunger 29 move to the right in the figure and interrupt the push-opening of the valve 27 by the bottle 3o, so that the valve 27 is seated on the valve seat 28 and the communication between the hydraulic inlet 25 and the hydraulic outlet 26 is interrupted. At the same time, the volume of the hydraulic chamber 31 increases, and the hydraulic pressure supplied to the wheel cylinder is corrected to reduce the pressure, thereby avoiding wheel locking.

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 27 is opened to increase the oil 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 oil pressure supplied to the wheel cylinder. It provides optimal control and performs the same anti-lock function as conventional anti-lock brake devices.

By the way, when the brake pedal 5 is released, the air downstream of the brake valve 3 is discharged from the brake valve 3, so that the air in the air chamber 15 is discharged through the holding valve z1, and the internal pressure thereof decreases. At this time, since the set pressure by the valve spring 24 is applied to the valve 23 of the holding valve 21, when the output pressure of the brake valve 3 decreases until it becomes equal to the set pressure by the set spring 23 of the valve spring 24, the valve 23 is seated on the valve seat 22 and the air on the downstream side thereof (air chamber 15
air inside). Therefore, the amount of air discharged (air consumption) generated when the brake pedal 5 is released is reduced. Further, once the air is trapped, no air will be supplied to the control cylinder 11 from the next braking if the output pressure of the brake valve 3 is below a predetermined value. For this reason, there is no need to provide a large-capacity air tank unlike in the past, and it is economical because an increase in the operation rate of the near compressor is suppressed.

In addition, since the air supply valve 16, exhaust valve 17, and holding valve 24 are incorporated into the air supply passage 13, exhaust passage, and return passage 20 of the housing 12, the entire device can be made smaller and lighter, and the anti-lock brake system It is possible to reduce the number of piping steps required when adding

Note that since only low-pressure air is confined within the control cylinder 11 of the modulator 6, the exhaust valve 17 cannot be opened even if a wheel lock occurs while the output pressure of the brake valve 3 is low. In this way, the internal pressure of the air chamber 15 can be quickly lowered, so that the operational response of the anti-lock brake system is not impaired.

In addition, in the embodiment, the air supply valve 16 is configured with an electromagnetic check valve to ensure responsiveness of operation while reducing the air pressure supplied to the air chamber 15 to reduce the load on the control cylinder 11. However, the air supply valve can also be configured with a normal on-off valve that does not have a pressure reducing function.

<Effects of the Invention> As is clear from the invention described above, according to the present invention, when the output pressure of the brake valve becomes less than a predetermined value, the holding valve closes to confine the air in the modulator. Therefore, an increase in air consumption due to the addition of an anti-lock brake device can be suppressed. In addition, since the holding valve that confines the air and the air supply valve and exhaust valve that control the pressure in the air chamber of the modulator are built into the housing of the modulator, the entire device can be made smaller and lighter, and the piping work can be reduced. etc. can also be reduced.

[Brief explanation of drawings]

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

Claims (1)

[Claims] (1) A brake valve operated by a brake pedal, a brake booster that generates hydraulic pressure in response to the air pressure output from the brake valve, and a hydraulic control valve that controls the hydraulic pressure supplied from the brake booster to the wheel cylinders. and a control cylinder to which the air output from the brake valve is supplied, an air supply passageway for guiding the air output from the brake valve to the air chamber of the control cylinder, and a return connected in parallel to the air supply passageway. a modulator having a housing provided with a passage and an exhaust passage connecting the air chamber to the atmosphere; an air supply valve provided in the air supply passage and closing the air supply passage when a wheel lock is detected; an exhaust valve provided in the exhaust passage to open the exhaust passage when a wheel lock is detected; and an exhaust valve provided in the return passage to open the exhaust passage when a lock of a wheel is detected; and an exhaust valve provided in the return passage to open the exhaust passage when the air pressure output from the brake valve is below a predetermined value. An anti-lock brake device for an automobile, comprising a holding valve that closes a passage.