JPS60248470A - Anti-skid control method of brake mechanism - Google Patents

Abstract

PURPOSE:To improve the brake efficiency without impairing the brake feeling of a driver by quickly decreasing the brake torque to avoid a lock of a wheel in a region where the angular deceleration of the wheel is larger than a predetermined value. CONSTITUTION:When the angular deceleration of a wheel is increased as the brake torque is increased and a lock of the wheel is impending, the first sensing switch 30 senses that the angular deceleration has reached a predetermined value (a) and is closed, thereby the normally-opened type second solenoid valve 21 is closed. At the same time, the set coil 27 of a keep relay 25 is energized via the switch 30 to close a contant 26, thus a solenoid valve 20 is energized and switched, and a high-pressure passage 17 is made conductive and a low-pressure passage 18 is cut off. Accordingly, the pressure oil from a pump 16 is fed to a pressure receiving chamber 13, and the pressure increase of the pressure receiving chamber 13 decreases the brake torque against the oil pressure of a pressure receiving chamber 12, thus a lock of the wheel is avoided.

Description

[Detailed Description of the Invention] The present invention prevents the wheels from skidding on the road surface by controlling the braking torque each time the braking torque is applied even if an excessive braking input is applied to the brake mechanism during braking of the vehicle, thereby achieving efficient braking. The present invention relates to an anti-skid control method for such a brake mechanism.

Conventionally, anti-skid control methods include reducing braking torque when wheel angular deceleration caused by excessive braking operation increases to a predetermined value or more, and when the resulting wheel angular acceleration decreases to a predetermined value. That is, there is a method of increasing the braking torque again when the circumferential speed of the wheels approaches the vehicle speed sufficiently.

However, as the braking torque decreases, the angular deceleration of the wheel disappears, and the next time angular acceleration occurs, there is already no risk of the wheel locking, so the braking torque is Reducing this causes the range of variation in braking torque to increase. In addition, when increasing the braking torque when the circumferential speed of the wheels approaches the vehicle speed, it must be done quickly, otherwise the time required for the braking torque to reach the appropriate value will be extended, resulting in Efficiency is significantly reduced. However, the rapid increase in braking torque causes large vibrations in the vehicle, which impairs braking sensation.

An object of the present invention is to provide the above-mentioned anti-skid control method that eliminates the above-mentioned problems in the conventional method.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
FIG. 1 shows an anti-skin braking device used to carry out the method of the present invention, which includes a brake operating hydraulic pressure generating device 1 and a brake installed on any wheel of a vehicle and operated by the output hydraulic pressure of the device 1. mechanism 2 and the device 1
The control device 3 controls the braking torque of the brake mechanism 2 by applying a hydraulic pressure that opposes the output hydraulic pressure of the brake mechanism 2 to the brake mechanism 2.The configuration of the control device 3 will be explained in sequence.

A well-known brake mask cylinder is used as the brake hydraulic pressure generating device 1, and can generate output hydraulic pressure by compressing a pressurizing chamber 6 filled with hydraulic oil with a pressurizing piston 5 connected to the brake pedal 4. can.

The hydraulic brake mechanism 2 includes a brake drum 7 that rotates together with the wheels, and a pair of brake shoes 8 that are floatingly or swingably supported on a fixed panel (not shown) inside the drum 7.
, 8, and a wheel cylinder 9 interposed between the movable ends of both brake shoes 8.8, and the wheel cylinder has piston rods 10a, 10a connected to the movable ends of the brake shoes 8.8. A pair of output pistons 10
A first pressure receiving chamber 12 is formed between the Okayama pistons 10 and 10, and a second pressure receiving chamber 13 and 13 is formed between each of the output pistons 10 and 10 and the end wall member 11.11 of the wheel cylinder 9. The first pressure receiving chamber 12 forms the pressurizing chamber 6.
is connected to via a flow path 14.

The control device 3 has an oil sump 15, a hydraulic pump 16 serving as a hydraulic pressure source with an inlet communicating with the oil sump, a high pressure passage 17 extending from its discharge port, and a low pressure passage 18 having an end open to the oil sump 15. The flow paths 17.18 are both connected to the second pressure receiving chamber 13.1.
Connected to 3. A first solenoid valve 20, which is a control valve that can switch and communicate them to the second pressure receiving chamber 13, is interposed between the two flows ii'i:17. The passage 18 communicates with the second pressure receiving chambers 13, 13. Furthermore, a normally open second solenoid valve 21 serving as a control valve is interposed in the low pressure flow path 18, and a first solenoid valve 20 is interposed therein.
A side passage 18a that bypasses and communicates with the second pressure receiving chamber 13.13
are connected, and an orifice 19 is formed in the middle of the side passage 18a. Note that 22 in the figure is a pressure accumulator.

FIG. 2 shows the electric circuit of the command unit W23 that controls the first and second solenoid valves 20.21.
0 solenoid is connected to the battery 2 battery 29 via the contact 26 of the keep relay 25. The keep relay 25 has a set coil 27 that can set the contact 26 to the closed position when energized, and a reset coil 28 that can reset the open contact 26 to the open position when energized. A first sensing switch 30 is inserted in a circuit connecting the reset coil 28 and the battery 29, and a second sensing switch 31 and a diode 24A are inserted in series in a circuit connecting the reset coil 28 and the battery 29. Immediately after the rain detection switch 30, 31, the solenoid of the second solenoid valve 21 is connected to the diodes 24B, 24.
Connect via C. The first sensing switch 30 senses an angular deceleration of a wheel braked by the brake mechanism 2 of a predetermined value 3 or more, and the second sensing switch 31 senses an angular acceleration of the same wheel of a predetermined value or more. Since a well-known inertial force sensing switch can be used for these, a description of the structure thereof will be omitted.

Next, the operation of the above embodiment will be explained with reference to the characteristic diagram in FIG. 3. While the vehicle is running, at the time of to, the brake pedal 4 is depressed and the brake mask cylinder 1 is actuated.
When the output oil pressure is applied to the first pressure receiving chamber 12 of the wheel cylinder 9, the pair of output pistons 10.1
0 are pushed outward to each brake shoe 8,8.
Since the brake drum 7 is pressed against the inner surface of the brake drum 7, a braking torque corresponding to the oil pressure in the first pressure receiving chamber 12 is applied to the wheels.

When the angular deceleration of the wheels increases as the braking torque increases and the wheels are in danger of locking, that is, when the angular deceleration of the wheels reaches the set value a, the first sensing switch 30 senses this. As it closes, the normally open second solenoid valve 21 is energized through the first sensing switch 30 and opens. At the same time, the cent coil 27 of the keep relay 25 is energized through the first sensing switch 30 and the contact 26 is closed, through which the first solenoid valve 20 is also energized and switched to the right side in FIG. While the passage 27 becomes conductive, the low pressure passage 18 becomes disconnected, and the wheel cylinder 9
The second pressure receiving chambers 13, 13 are supplied with pressure oil from the hydraulic pump 16 or the pressure accumulator 22, and the oil pressure is supplied to the first pressure receiving chamber 12.
Therefore, the braking torque applied to the wheels of the brake mechanism 2 is quickly reduced in response to the increase in pressure in the second pressure receiving chambers 13, 13, and the risk of wheel locking is eliminated.

When the angular deceleration generated in the wheel decreases to the set value a as a result of the reduction in braking torque, the first sensing switch 30 opens again at t2, and the second solenoid valve 21 returns to the original state of the first [g+. Since the right switching shape fm of the first electromagnetic valve 20 is connected by the keep relay 25, the second pressure receiving chamber 13.13 has an orifice 19 and a low pressure flow path 1 through the side path 18a.
Accordingly, a part of the pressure oil supplied from the high pressure channel 17 to the second pressure receiving chamber 13.13 leaks to the low pressure channel 17 while the flow rate is appropriately restricted by the orifice 19. The rate of increase in pressure in the pressure receiving chambers 13, 1.3 is reduced, and therefore the rate of decrease in braking torque can be reduced.

After that, the angular deceleration of the wheels disappears, and the ground speed occurs, and when it reaches the set value 13, the second sensing switch 31 senses this state and closes, so the keep relay 25 The glue cent coil 28 is energized and the contact 26
By resetting 21 to the open position, the first electromagnetic valve 20 returns to its original state (left side) in FIG. 1, and on the contrary, the second electromagnetic valve 21 is energized again and enters the closed state. the result,
Both the high pressure and low pressure channels 17.18 are completely cut off, and the pressure in the second pressure receiving chamber 13.13 is held constant regardless of the output oil pressure of the brake mask cylinder l. Even if there is some time delay in the operation of the valve 21, immediately before that, the second pressure receiving chambers 13, 13
Since the pressure increase speed of 2nd pressure receiving chamber L3.13 is decreasing,
This prevents the pressure from increasing too much, and therefore it is possible to continue applying a predetermined braking torque within a range that does not cause the wheels to overshoot.

After that, the road speed of the wheels starts to decrease as the circumferential speed of the heavy wheels approaches the vehicle speed, and when the circumferential speed of the wheels approaches the vehicle speed sufficiently, it returns to the set value at t4, and the second sensing switch 3
1 opens, the second solenoid valve 21 returns to the open state and makes the low pressure flow path 18 conductive, so that the second pressure receiving chamber 13
．． 1.3 starts again, the braking torque increases accordingly, and the time required for the braking torque to reach the next peak value from the constant value is relatively short, so that the circumferential speed of the wheels decreases to the vehicle speed. The time wasted in braking that is close enough to the vehicle is reduced. Thereafter, the same operation is repeated, and the wheels are efficiently braked without skidding.

By the way, when the vehicle stops due to the operation of the braking device 3,
There is no guarantee that the second sensing switch 31 will close and the keep relay 25 will be reset. If the keep relay 25 is in the center state, that is, if the vehicle stops with the contact 26 closed, the second pressure reception? ; Since the high pressure state of ≦13.13 is maintained for a relatively long time due to the throttling effect of the orifice 19,
This may interfere with the next braking operation.

In view of this, the command device 23 has an off-day timer 3 driven by the output signal of the first sensing switch 30.
The second contact 33 is connected to the reset coil 28 of the keep relay 25 in parallel with the second sensing switch 31. The contact 33 of the off-tray receiver 32 is in the open position in the reset state, and from the time the first sensing switch 30 is closed,
The sensing switch 30 is closed (sent state) only for a certain period of time after it is opened again.

Therefore, if the first sensing switch 30 opens and chirps,
Even if the second sensing switch 31 does not close, the keep relay 25 can always be reset by the reset action of the off-delay timer 32 after a certain period of time has elapsed, so the above-mentioned problem is solved. However, the delay time from when the first sensing switch 30 opens to when the contact 33 opens is limited to the time from when the first sensing switch 30 opens to when the second sensing switch opens so as not to interfere with normal anti-skid control. It goes without saying that the time must be set larger than the time it takes for the second channel 31 to close (usually 0.05 seconds or less).

As described above, according to the present invention, when the angular acceleration of the wheel occurs and falls below a predetermined value during braking, the braking torque is promptly reduced, and as a result, the angular acceleration of the wheel increases above the predetermined value. In an anti-skid control method for a brake mechanism, which repeats the steps of maintaining a constant braking torque when the angular acceleration decreases below a predetermined value, and then increasing the braking torque when the angular acceleration decreases below a predetermined value, When the angular deceleration representing a negative acceleration further decreases from the lowest predetermined value set, the rate of decrease of the braking torque is reduced, and then an angular acceleration representing a positive angular acceleration of the wheel is generated to the predetermined value. When the angular deceleration of the wheels exceeds a predetermined value, the reduction in braking torque is stopped and kept constant, so in a region where the angular deceleration of the wheels is greater than a predetermined value, the braking torque can be rapidly reduced to avoid wheel locking. In addition, the angular deceleration of the wheel is reduced to a low predetermined value or less due to the sudden decrease in braking torque, but the angular acceleration of the wheel that exceeds the predetermined value has not yet occurred, and there is no risk of wheel locking. By reducing the rate of decrease in braking torque, it is possible to effectively prevent an excessive decrease in braking torque while reliably avoiding wheel locking, and as a result, the decrease in braking torque can be kept to the minimum necessary level. , and when the braking torque is increased next time, the fluctuation width and time until the braking torque reaches its peak value can be significantly shortened.
It is possible to quickly obtain effective braking torque without causing large vibrations to the vehicle, and as a result, braking efficiency is improved without impairing the driver's braking sensation, and the braking distance of the vehicle can be shortened. It is.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram of an anti-skid brake device used to carry out the method of the present invention, FIG. 2 is an electric circuit diagram of the command device, and FIG. 3 is a characteristic diagram of the command device. Patent applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] During braking, when the angular acceleration of the wheel decreases below a predetermined value, the braking torque is promptly reduced; as a result, when the angular acceleration of the wheel increases above the predetermined value, the braking torque is maintained constant; In an anti-skid control method for a brake mechanism that repeatedly increases braking torque when acceleration falls below a predetermined value, an angular deceleration representing negative angular acceleration of the wheel is set in the process of reducing the braking torque. When the braking torque decreases further below the lowest predetermined value, the rate of decrease of the braking torque is reduced, and when an angular acceleration representing a positive angular acceleration of the wheel occurs and exceeds the predetermined value, the braking torque decrease is stopped and kept constant. An anti-skid control method for a brake mechanism, characterized in that the anti-skid control method maintains the brake mechanism.