JPS63188556A - Antiskiding device for automobile - Google Patents

Abstract

PURPOSE:To easily provide an antiskid mechanism which has hill holder function (function of holding a brake state on an upward slope), by providing a liquid pressure increasing mechanism which forcibly feeds a brake liquid pressure to a brake device during a brake stop on an upward slope. CONSTITUTION:When a vehicle is stopped by stepping on a brake pedal 1 on an upward slope, based on outputs from a wheel speed sensor 15, a brake pedal switch 16, and a gradient sensor 17, a hill hold signal is outputted from a control unit 14 to a third control valve 5. By means of the signal, the third control valve 5 is opened only in a direction extending from the maser cylinder 2 side to a brake device 4, and in the case of the reverse direction, the third control valve is switched to a closed state. Pressure liquid remaining in a reservoir 9 is applied through a relief valve 12 and a first control valve 6 on the brake device 4. With this state, even if a foot is separated from the pedal 1, a brake force is held, and a liquid pressure by an electromagnetic pump 10 is exerted on the brake device 4 to hold a sufficient brake force.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an anti-skid device for a motor vehicle.

Conventional technology In hydraulic brake systems for automobiles, when braking is performed by depressing the brake pedal and hydraulic pressure is supplied from the master cylinder to the wheel cylinder, the rate and amount of decrease in wheel speed relative to the vehicle body speed is detected, and the rate and amount of decrease in wheel speed are detected. Various anti-skid devices have been developed in the past, which alternately control the pressure reduction and pressure increase of the supplied brake fluid pressure to perform effective braking without locking the wheels and losing directional stability. It has already been published in Japanese Patent Application Laid-Open No. 80-61354.

On the other hand, in order to make it easier to maintain the brake on a hill and start on a hill, as long as the clutch is off when braking and stopping on a hill, the braking state will not be maintained even if you release your foot from the brake pedal. A system in which a brake fluid pressure holding valve is inserted in the brake fluid pressure piping (generally called a hill holder) so that the brake fluid pressure is held as it is and released from the above-mentioned brake holding state in conjunction with the on-action of the clutch at the time of starting. Various methods have already been developed, such as Utility Model Application No. 55-33822.
No. 1, Japanese Patent Application Laid-Open No. 56-34550, etc.

Problems to be Solved by the Invention In recent years, automobiles have become required to be equipped with both an anti-skid device and a hill holder in order to improve safety during high-speed driving and to satisfy user demands for easier driving operations. However, installing two independent mechanisms such as the anti-skid device and the hill holder as described above in the brake hydraulic system would not only be structurally complex but also quite expensive in terms of cost. Become.

The present invention aims to solve the above problems,
The present invention aims to provide an anti-skid device having a hill holder function with a large braking force by providing a hydraulic pressure increasing mechanism.

Means for Solving the Problems The present invention provides a normally open first control line that is closed by a hold signal from a control unit in a main hydraulic line that supplies braking hydraulic pressure from a master cylinder to a brake device for each wheel. A valve is provided in a sub-hydraulic line bypassing the upstream and downstream sides of the first control valve of the main hydraulic line, which is opened in response to a pressure reduction signal from the control unit and stores the hydraulic pressure in the brake device into a reservoir. A normally closed second control valve that allows fluid to flow into the reservoir, and a pump that pumps up the fluid pressure that has flowed into the reservoir and supplies it to the upstream side of the first control valve in the main hydraulic pressure system path through a relief valve, and when the brake pedal is depressed. During a braking operation, the control unit issues a signal in response to a change in wheel speed relative to the vehicle body speed, and operates the first control valve and the second control valve to reduce and increase the hydraulic pressure in the brake device. In an automobile anti-skid system that performs braking control by repeating a control pattern, the main hydraulic line is connected to the master cylinder in the direction of the brake system by a signal from the control unit, but not in the opposite direction. A normally open third control valve is provided that switches to a closed one-way valve, and when the road surface is uphill and the vehicle speed drops to an extremely low speed close to stopping after performing a braking operation, the control unit issues a signal to The third control valve is switched to a one-way valve, and the pump is activated to supply the pressure fluid stored in the reservoir to the brake device, so that the brake fluid pressure in the brake device is maintained sufficiently even when the brake pedal is released. In addition, when a predetermined vehicle starting condition occurs in this braking force holding state, the control unit switches the third control valve to an open state and issues a signal to release the brake holding state. It is characterized by the following structure.

As described above, when the vehicle speed drops below an extremely low speed close to stopping during braking on a one-slope road, the third control valve switches from the open state to the one-way valve state, and the pressure fluid stored in the reservoir is switched from the open state to the one-way valve state. The relief valve and the first opening are opened by pump operation.
It is supplied to the brake device via the control valve to increase braking force, and even when the brake pedal is released, the increased braking fluid pressure in the brake device does not drain to the master cylinder side, providing a high level of braking force. The braking force is maintained.

When the accelerator pedal is pressed to start from this brake holding state and the forward torque acting on the wheels exceeds a predetermined value, the third control valve is switched to the open state by a signal from the control unit, and the hydraulic pressure of the brake system is released. When the transmission is shifted to the reverse position in order to move backward in the above-mentioned brake holding state, the third control valve is opened by a signal from the control unit. The brake system's hydraulic pressure is released and the vehicle is ready to move backwards.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a brake pedal, and 2 is a master cylinder. When brake pedal 1 is depressed, master cylinder 2 is activated, and brake fluid pressure is applied to pipes 31, 32 and 33.
The main fluid passes through the main fluid main path 3 to the brake device 4 of each wheel.
(The illustration shows only one wheel brake system).

The main hydraulic line path 3 includes a normally open third control valve 5 that switches to a one-way valve only when a hill hold signal S5 is issued from the control unit 14, which will be described later, and A normally open first control valve 6 that is closed by a hold signal S2 is provided.

Reference numeral 7 denotes a sub-hydraulic pressure line that bypasses the downstream and upstream sides of the first control valve 6 of the main hydraulic line 3, and the sub-hydraulic line 7 is connected to a normally closed second control valve. 8 is opened, the pressure fluid in the brake device 4 is released to the reservoir 9 to reduce the pressure in the brake device 4, and the pressure fluid released to the reservoir 9 is pumped out by the operation of the electromagnetic pump 10 to the accumulator 11. It is composed of pipes 72 and 73 for storage, and a pipe 74 for sending the pressure liquid stored in the accumulator 11 to the upstream side of the first control valve 6 via the relief valve 12.

There is a valve between both ends of the first control valve 6 that operates when the brake fluid pressure on the downstream side of the first control valve 6 becomes smaller than the brake fluid pressure on the upstream side. A differential pressure valve 13 is provided to close the hydraulic pressure passage.

In the above, when the brake pedal 1 is depressed, hydraulic pressure is supplied from the master cylinder 2 to the brake device 4 through the main hydraulic pressure line 3, and at the same time, the brake device 4 is activated and the rotational speed of the wheel is reduced. Brake pedal switch 1
6 is activated and the braking signal 31 is sent to the control unit 14.
The control unit 14 starts anti-skid operation based on the wheel speed signal Sw from the wheel speed sensor 15.

That is, for example, when the degree of decrease in wheel speed (deceleration) exceeds a set value, the control unit 14 issues a hold signal S2, closes the first control valve 6, and reduces the hydraulic pressure supplied from the master cylinder 2 to the brake device 4. The shaft is turned off to maintain the hydraulic pressure in the brake device 4, and when the wheel speed decreases to a certain set value with respect to the vehicle body speed, the control unit 14 issues a pressure reduction signal S3 and causes the brake device 4 to pass through the second control valve 8. The pressure fluid in the reservoir 9 flows into the reservoir 9 through the pipe 33.71 to reduce the pressure in the brake device 4, and the pressure fluid flowing into the reservoir 9 is pumped out through the pipe 72 by the operation of the electromagnetic pump IO, and the pressure fluid flows into the reservoir 9 through the pipe 73. The hydraulic pressure in the accumulator 11 is applied via the relief valve 12 to the upstream side of the first control valve 6 which is in the closed state. The difference in braking fluid pressure between the upstream side and the downstream side of the control valve 6 causes the differential pressure valve 13 to operate and close the hydraulic passage between the first control valve 6 and the master cylinder 2, so that the electromagnetic pump lO The pulsation of hydraulic pressure accompanying the operation of the brake pedal does not act on the master cylinder 2 side, and the problem of brake pedal kickback can be prevented.

When the pressure in the brake device 4 is reduced as described above, the wheel speed increases due to road reaction force, and when the wheel speed recovers to a certain value, the control unit 14 stops the pressure reduction signal S3 and the second control valve 8 is closed, and when the wheel rotation speed has recovered to near the vehicle body speed, the control unit 14 issues a pressurization signal Sa (in this case, stopping the hold signal S2 becomes the pressurization signal) and performs the first control. The valve 6 is switched to the open state, the pressure oil stored in the accumulator 11 is supplied to the brake device 4, the brake device 4 is put into a pressurized state, and the wheel speed decreases.

From then on, the control unit 14 outputs the hold signal 52.
, a pressure reduction signal S3, and a pressure increase signal S4 are sequentially issued to alternately repeat pressure reduction and pressure increase of the brake device 4, and in this way, effective braking is performed without locking of the wheels.

When the brake pedal 1 is released during the anti-skid operation in which the brake device 4 is alternately depressurized and pressurized as described above, the signal Sl from the brake pedal switch 16 disappears and the anti-skid signal from the control unit 14 is released. The skid control operation is stopped, the first control valve 6 is kept open and the second control valve 8 is kept closed, and the hydraulic pressure of the brake device 4 is drained to the master cylinder 2 side through the main hydraulic line 3. Braking is released.

In the above, when the brake pedal 1 is first depressed, the control unit 14 temporarily opens the second control valve 8 as shown in FIG. A part of the pressure fluid supplied to the brake device 4 is taken into the reservoir 9, and during the subsequent anti-skid operation, the pressure fluid in the brake device 4 is further removed by opening the second control valve 8 based on the pressure reduction signal S3. It is taken into the reservoir 9 and sent out into the brake device 4 in response to a pressurization signal S4.

When depressing the brake pedal 1 to brake and stop on a climbing road, the slope sensor 17 is activated when the road surface is an uphill road.
A signal Sθ is input to the control unit 14, and a braking signal S1 from the brake pedal switch 16 is input to the control unit 14.
Based on the wheel speed signal Sw from the wheel speed sensor 15 and the slope signal Sθ from the slope sensor 17, the control unit 14 performs a braking operation on the uphill road to obtain an extremely low vehicle speed Vo close to stopping.
(for example, 3 km 8), and issues a hill hold signal S5 to the third control valve 5, and the third control valve 5 changes from the open state to the one-way valve state, that is, from the master cylinder 2 side to the brake device 4 direction. In the reverse direction, the hydraulic fluid is switched to a closed state, and the pressure fluid remaining in the reservoir 9 is applied to the brake device 4 via the relief valve 12 and the first control valve 6, which is open.

In this state, even if you release your foot from the brake pedal 1, the hydraulic pressure in the brake device 4 is not drained to the master cylinder 2 side, and not only maintains the brake, but also remains in the reservoir 9 due to the operation of the electromagnetic pump IO. By applying the same hydraulic pressure to the brake device 4, the brake device 4 can maintain sufficient braking force.

As the gradient sensor 17, for example, a G sensor is used, and the control unit 14 calculates the difference between the vehicle deceleration detected by the information from the wheel speed sensor 15 and the G signal input from the G sensor (see Fig. 2). However, it is possible to adopt a method of detecting the road surface slope based on the difference δ.

When starting from this brake holding state, the forward torque acting on the wheels increases in response to the depression of the accelerator pedal 1, and a torque signal St is sent to the control unit 14 from the torque sensor 18 that detects this torque and operates.
is input into. Then the control unit)14
is the hill hold signal S5 by the torque signal St.
stops and the third control valve 5 returns to its original state as shown in Fig. 2, the hydraulic pressure of the brake device 4 is drained to the master cylinder 2 side, the braking is released, and the vehicle starts on the uphill road. can be easily done.

When the transmission is put into reverse gear in an attempt to reverse after braking to a stop on the uphill road, the reverse switch 19 is activated and sends a reverse signal Sr to the control unit 14, which causes the control unit 14 to activate the hill hold signal S5. Stops transmission and releases brake hold.

If the driver opens the door and tries to leave the car while the brake is still in the above-mentioned state, the door open signal Sd is input to the control unit 14 from the door switch 20 activated by opening the door, and the control unit 14 receives the signal. Sd activates an alarm device 21 such as a buzzer to issue a warning to the driver. In this case, when the parking brake lever is operated to apply the parking brake, the parking switch 22 sends the signal Sp to the control unit 1.
4, the control unit 14 stops transmitting the hill hold signal S5, releases the brake hold, and stops the alarm 21 if it is operating.

Reference numeral 23 denotes an operation indicator lamp, which lights up in response to a signal from the control unit 14 when the third control valve 5 is in the brake holding state to indicate that the brake is in the holding state.

Further, even if the key switch of the engine is turned off without applying the parking brake in the brake holding state, the control unit 14 activates the alarm 21 such as a buzzer to warn the driver to apply the parking brake.

As mentioned above, the information of each sensor switch necessary for the hill holder is incorporated into the control unit 14 for anti-skid control, and the brake fluid pressure is supplied to the brake device 4 by a pump to increase the braking force when the brake is stopped on the uphill road. By providing a hydraulic pressure increasing mechanism, it is possible to easily realize a hill holder function with a large braking force using a conventional anti-skid system.

If the braking force is still insufficient even after increasing the braking force by operating the hydraulic pressure increasing mechanism, press the brake pedal 1 more strongly to further increase the hydraulic pressure in the brake device 4 to provide sufficient braking force. Obtainable.

Furthermore, in the above embodiment, the third control valve 5 is switched to a one-way valve only when the brake is stopped on the uphill road, but the third control valve 5 is switched to a one-way valve only when the braking is stopped on the uphill road, but it is also switched not only when the brake is stopped on the uphill road, but also during anti-skid operation. When the electromagnetic pump 10 is operated, the third
The control valve 5 may be configured to be switched to a one-way valve, and in this way, the pulsation of hydraulic pressure accompanying the operation of the electromagnetic pump 10 is transferred to the master cylinder 2 side by the one-way valve of the third control valve 5. Therefore, the differential pressure valve 1 shown in the first diagram
3 can be omitted.

Effects of the Invention As described above, according to the present invention, when braking is performed when the brake pedal is depressed and braking fluid pressure is supplied from the master cylinder to the brake device of each wheel, the system detects the wheel speed based on the wheel speed signal of the wheel speed sensor that detects the wheel speed. The control unit issues a signal to repeat the control pattern of reducing and repressurizing the brake fluid pressure in the brake system of each wheel, thereby ensuring effective braking without locking the wheels. In skid devices, slope sensors detect whether the road surface is uphill, torque sensors detect the forward torque acting on the wheels, reverse switches detect when the transmission has been shifted to the reverse position, etc. Necessary as hill holders A hydraulic pressure increase mechanism is equipped with various sensor switches, and the information of the sensor switches is incorporated into the control unit of the anti-skid device, and forcibly supplies brake fluid pressure to the brake device when braking on a hill. With this, it is possible to easily obtain an anti-skid device with a hill holder function with high braking force, and various sensors for anti-skid control, braking hydraulic pressure piping, various control valves, etc. can be used as a hill holder. Since it can be used commonly for control purposes, it can save space, reduce costs, etc., and can also improve the added value of the anti-skid device, which can bring about great practical effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an operation according to the present invention. 1... Brake pedal, 2... Master cylinder, 3
...Main hydraulic pressure system line, 4...Brake device, 5...Third control valve, 6...First control valve, 7...Sub-hydraulic pressure system line,
8... Second control valve, 9... Reservoir, 10... Electromagnetic pump, 11... Accumulator, 12... Relief valve, 13... Differential pressure valve, 14... Control unit, 15... Wheel speed sensor, 16... Brake pedal switch, 17... Gradient sensor, 18...
...Torque sensor, 19...Reverse switch, 20
...Door switch, 21...Alarm, 22...Parking switch, 23...Operation indicator light. that's all

Claims (1)

[Claims] A normally open first control valve that is closed by a hold signal from the control unit is provided in the main hydraulic pressure line that supplies braking hydraulic pressure from the master cylinder to the brake equipment of each wheel,
A sub-hydraulic line bypassing the upstream and downstream sides of the first control valve of the main hydraulic line is opened in response to a pressure reduction signal from the control unit and causes the hydraulic pressure in the brake device to flow into the reservoir. A second control valve that is closed, and a pump that pumps up the hydraulic pressure that has flowed into the reservoir and supplies it to the upstream side of the first control valve in the main hydraulic pressure line through a relief valve are provided, and when a braking operation is performed by depressing the brake pedal. A control pattern in which the control unit issues a signal in response to a change in wheel speed relative to the vehicle body speed and operates the first control valve and the second control valve to reduce and then increase the hydraulic pressure in the brake device. In an automobile anti-skid system that repeatedly performs braking control, the main hydraulic line is connected to the master cylinder in the direction of the brake system by a signal from the control unit, but is closed in the opposite direction. A normally open third control valve that switches to a directional valve is provided, and when the road surface is on an uphill slope and the vehicle speed drops below an extremely low speed close to stopping after performing a braking operation, the control unit issues a signal to close the third control valve. Switches the brake to a one-way valve and operates the pump to supply the pressure fluid stored in the reservoir to the brake system, maintaining sufficient braking fluid pressure in the brake system even when the brake pedal is released. and the control unit is configured to issue a signal to switch the third control valve to the open state and release the brake hold when a predetermined vehicle start condition occurs in the brake force hold state. Features of automotive anti-skid device.