JPH06211118A - Vehicle turning preventive method - Google Patents

Abstract

PURPOSE:To prevent a vehicle turning owing to the locking of driving wheels following an auxiliary braking operation. CONSTITUTION:When it is discriminated that a vehicle turning is started following a rear wheel locking owing to the operation of a retarder as an auxiliary brake, the processor of an ECU 15 stops the delivery of the retarder drive control output through a retarder driving circuit 130, and at the same time, one side relay valve corresponding to the vehicle turning direction, of the relay valves built in ABS valve units IOL and IOR, is operated so as to apply a braking force to one side of the front wheels, and the further turning of the vehicle is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle turning prevention method, and more particularly, it can prevent vehicle turning which tends to occur due to a braking operation of an auxiliary brake device when a vehicle is traveling on a road surface having a small friction coefficient. Vehicle rotation prevention method.

[0002]

2. Description of the Related Art An auxiliary brake device for generating a braking force by reducing a driving force transmitted to driving wheels is mounted on a large vehicle such as a truck to improve the durability of a service brake device. It is known.
Conventionally, for example, an exhaust brake in which an opening / closing valve arranged in an exhaust pipe of an engine reduces an exhaust pipe passage area to increase engine exhaust pressure to obtain a braking force is known as an auxiliary brake. In addition, an electromagnetic retarder that performs a braking operation by forming a magnetic field in the vicinity of a rotor that rotates integrally with a propeller shaft to release the rotational energy of the rotor as heat energy, and a stator provided on the engine body side and a crankshaft side of the engine There is known a hydraulic retarder that performs a braking operation by supplying hydraulic oil between the rotor and the rotor provided therein to absorb the kinetic energy of the rotor. Further, a power tard is also known as an auxiliary brake, which shuts off the fuel supply to the engine and creates a positive pressure in the combustion chamber when the piston rises and a negative pressure in the cylinder when the piston descends. The braking force is generated by adjusting the timing.

The above various auxiliary brake devices are useful in that the braking force is generated in accordance with the ON operation of the auxiliary brake switch by the driver to reduce the load on the service brake device.

[0004]

However, the auxiliary brake is inadvertently applied while the vehicle is traveling, especially when a truck not loaded with luggage is traveling on a road surface having a low friction coefficient such as an icy road. Therefore, the running stability of the vehicle may be impaired. That is, the frictional resistance generated between the traveling road surface and the wheels mainly changes depending on the traveling road surface state, and becomes small on the low μ road. Therefore, on low μ roads, the braking force applied to the drive wheels by the auxiliary brake is
The frictional resistance between the road surface and the drive wheels may be exceeded, in which case the drive wheels will lock. In a rear-wheel drive vehicle, if the rear wheel as a drive wheel locks, vehicle rotation may occur.

In order to prevent the vehicle from turning due to the braking operation of the auxiliary brake, it is sufficient to deactivate the auxiliary brake.
It is actually difficult for the driver to turn on and off the operation of the auxiliary brake according to the road surface condition, and there is a safety problem. Also, if the rear wheels were once locked by the braking operation of the auxiliary brake and then the operation of the auxiliary brake was simply released,
The vehicle cannot be prevented from turning due to the rear wheel lock that accompanies the operation of the auxiliary brake.

Therefore, the present invention provides a vehicle rotation preventing method capable of preventing vehicle rotation which is likely to occur due to the braking operation of the auxiliary brake device when the vehicle is traveling on a road surface having a small friction coefficient. To aim.

[0007]

A vehicle rotation preventing method according to one aspect of the present invention determines whether vehicle rotation has started when the rear wheels are locked due to the braking operation of an auxiliary brake device, and the vehicle rotation is determined. When is started, the braking force is applied to one of the front wheels corresponding to the vehicle turning direction.

According to another aspect of the present invention, there is provided a vehicle turning prevention method, wherein it is determined whether vehicle turning has started when the rear wheels are locked due to the braking operation of the auxiliary brake device, and when vehicle turning starts, The front wheels are steered in a direction opposite to the turning direction.

[0009]

When the vehicle is traveling, whether or not the rear wheels as the drive wheels are locked is determined by a method known in the field of anti-skid brake systems. Then, when the rear wheel lock is detected, it is determined whether or not the rear wheel lock is caused by the braking operation of the auxiliary brake device. For example, when the rear wheel lock state is detected and the brake of the rear wheel is in the inoperative state, it is determined that the rear wheel is locked by the auxiliary brake operation. Then, when such a determination result is obtained, it is further determined whether or not vehicle turning has started by monitoring the output of the lateral acceleration sensor, for example. Next, when the vehicle turns, the braking force is applied to one of the front wheels corresponding to the vehicle turning direction, or the front wheels are steered in the direction opposite to the vehicle turning direction. For example, when the vehicle turns right, braking force is applied to the right front wheel, or the front wheel is steered to the left. As a result of the application of the braking force or the steering of the front wheels, an action force that prevents the vehicle from turning is applied to the vehicle body, and further vehicle turning is prevented. On the other hand, the braking force application is stopped immediately thereafter, or the front wheels are returned to the straight traveling position, so that the running stability and maneuverability of the vehicle are not impaired.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle to which the vehicle turning prevention method according to the first embodiment of the present invention is applied will be described below. The vehicle to which the method of the present embodiment is applied is, for example, a large vehicle such as a rear wheel drive type bus or truck, and includes an electrically controlled air brake system and a three-channel anti-skid brake system (ABS) for the air brake. ) And a hydraulic retarder as an auxiliary braking device.

Referring to FIG. 1, in the air brake system, the air tanks 1 and 2 for the front and rear brakes are connected to a brake brake valve 3 via conduits 20 and 21, respectively. The brake valve 3 is, on the one hand, connected to the ABS of an anti-skid brake system, which will be described later, via the conduit 22 and its branch conduits 22L and 22R.
The relay valves (not shown) connected to the left and right front wheels respectively built in the valve units 10L and 10R are connected to each other. Is omitted).

The two relay valves for the left and right front wheels are respectively connected to the air tank 1 via the conduit 24 and the branch conduits 24L and 24R thereof on the one hand, and the conduit 26 on the other hand.
Brake chambers 7 for the left and right front wheels via L and 26R,
7'is connected to each. On the other hand, the relay valve for the rear wheels is connected to the air tank 2 via the pipe 25 on the one hand, and is connected to the rear brake chambers 8 and 8 ′ for the left and right rear wheels on the other hand via the pipe 27. .

Immediately downstream of the brake valve 3, pressure sensors 13 and 14 for sending electric signals representing the internal pressure (air pressure) of both pipelines are connected to the pipelines 22 and 23, respectively.
Both pressure sensors are connected to an electronic control unit (ECU) 15 including a processor, a memory, an input / output circuit and the like. The ECU 15 takes in a pressure sensor output signal and sends a relay valve control signal corresponding thereto to the left and right front wheel and rear wheel relay valves.

Each relay valve has a signal pressure (air pressure) supplied as a control signal from the brake valve 3 and an ECU.
It is made responsive to both the electric signal supplied from 15 as a control signal. That is, each relay valve constitutes an electric control brake (EBS) that interrupts the signal pressure from the brake valve 3 and preferentially responds to the electric signal, while the signal pressure from the brake valve 3 is generated when the electric system fails. It composes a complete air brake that responds to.

In the above structure, when the brake pedal 4 is depressed, the brake valve 3 operates according to the pedal depression amount, and the air pressure in the air tanks 1 and 2 is increased by the valve 3.
Is supplied to the pipelines 22 and 23 via the internal pressure of the pressure sensors 13 and 14 and the internal pressures of the pipelines increase.
And the pressure sensor output is applied to the ECU 15. The ECU 15 sends a control signal corresponding to the pressure sensor output to the left and right front wheel and rear wheel relay valves, and the air pressure from the air tanks 1 and 2 is transmitted to the front brake chambers 7 and 7 ′ via the relay valves responsive thereto. And the rear brake chambers 8 and 8 ', which actuate the brake chambers 7 to 8' to apply a braking force to the front and rear wheels of the vehicle. On the other hand, when the driver depresses the brake pedal 4, the air between the brake valve 3 and the relay valves of the left and right front wheels and the rear wheels is discharged from the valve 3, and the braking of the front wheels and the rear wheels is released. It

When a control signal is no longer sent from the ECU 15 to each relay valve due to a failure in the electrical system, the relay valve responds to the signal pressure from the brake valve 3. That is, when a signal pressure is supplied from the brake valve 3 to the relay valve in response to the depression operation of the brake pedal 4, compressed air having a pressure corresponding to the signal pressure is supplied to the air tank 1,
2 is supplied to the brake chambers 7 to 8'through a relay valve, and a braking force is applied to the front wheels and the rear wheels.

Next, the three-channel anti-skid brake system mounted on the vehicle is composed of a processor, a memory, an input / output circuit, etc., and is configured to be capable of exchanging signals with the ECU 15 of the electrically controlled brake system.
The S controller 31 is provided with a wheel speed sensor 32, 33 and 34 for detecting wheel speeds VFL, VFR and VR of the left front wheel, the right front wheel and the rear wheel, respectively.
And a vehicle speed sensor 35 for detecting the vehicle speed V are connected.

The ABS controller 31 calculates the slip ratios of the left front wheel, the right front wheel and the rear wheel based on the output signals VFL, VFR and VR from the wheel speed sensors 32 to 34 and the output signal V from the vehicle speed sensor 35, The ABS signals a1 to a3 having signal levels according to the calculated slip ratio are supplied to the ABS valve units 10L, 10R and 11 of the left front wheel, the right front wheel and the rear wheel. ABS signal a1
a3 is the brake chamber 7 depending on the signal level.
It functions as a pressure increase signal for letting compressed air into 8-8 'or a pressure reducing signal for letting compressed air out of the brake chambers 7-8'. When the wheel slip ratio exceeds a predetermined value, the controller 31 sends out a pressure reducing signal. To be done.

Although not shown in detail, each of the ABS valve units 10L, 10R and 11 has a solenoid valve responsive to the ABS signal a1, a2 or a3, and each solenoid valve serves as a pressure reducing signal. AB
In response to the S signal, it operates to bleed compressed air from the corresponding one of the brake chambers 7-8 '.

Further, the vehicle is equipped with a hydraulic retarder as an auxiliary braking device. As illustrated in FIGS. 2 and 3, the hydraulic retarder 103 is disposed coaxially with the crankshaft 102 between the diesel engine 101 and the transmission 104, and more specifically, the flywheel 1
06 and a flywheel housing 107 screwed and fixed to the engine block 105. The retarder 103 includes a stator 110 provided on the flywheel housing 107 side and a rotor 111 attached to the crankshaft 102. The flywheel housing 107 has the hub 11 of the rotor 111 at the inner peripheral edge.
It is in liquid-tight contact with 1a. Retarder housing 108
Has an outer peripheral edge screwed and fixed to the flywheel housing 107, and an inner peripheral edge via the seal 112 through the rotor hub 11
It is in liquid-tight contact with 1a.

The retarder 103 is further provided with an oil pump 115 which is, for example, an internal gear pump, and is provided with a rotor 111.
The pump housing main body 116 housed inside is fitted to the rotor 111 via a seal member, and is rotatably supported by the rotor boss 111a via a bearing. The external gear 119 housed in the pump housing main body 116 is externally fitted and fixed to the rotor hub 111 a, which is the input shaft, and is rotatable integrally with the rotor 111. An electromagnetic clutch 121 including a return spring and a solenoid connected to the retarder drive circuit 130 (FIG. 1) is provided between the side plate 120 axially slidably fitted in the stator recess 110b and the end wall of the stator 110. Are arranged. The suction port of the oil pump 115 is connected to the hydraulic oil supply passage provided in the stator 110, the discharge port is opened in the retarder 103, and the hydraulic oil discharge passage is connected to the outer peripheral portion of the retarder. The hydraulic oil supply passage is connected to the oil tank, and the hydraulic oil discharge passage is connected to the oil tank via a switching valve, a relief valve and the like.

In the above structure, when the retarder switch 140 (FIG. 1) is turned on by the driver, a low level control output is sent from the ECU 15 which responds to this switch operation to the retarder drive circuit 130, which causes the electromagnetic clutch 121 to operate. Solenoid deenergized and clutch 1
21 turns off. In this case, the oil pump side plate 120
Is pressed against the end surface of the pump housing body 116 by the spring force of the return spring, and the oil pump 115 functions as a pump. That is, the operating oil is sucked from the oil tank by the external gear 119 that rotates together with the rotor 111 and fills the retarder 103, whereby the rotational energy of the rotor 111 is absorbed by the operating oil and the retarder 103 operates. On the other hand, the retarder switch 14
When 0 is turned off and the solenoid of the electromagnetic clutch 121 is energized, the oil pump side plate 120 is attracted to the solenoid and separated from the end surface of the pump housing main body 116, and as a result, the suction port and the discharge port of the oil pump 115. And communicate with each other, the pump function is released, and the retarder 103 is deactivated.

The vehicle turning prevention operation of the ECU 15 shown in FIG. 1 will be described below. When the ignition key of the vehicle is turned on, the processor of the ECU 15 periodically executes a vehicle rotation prevention routine shown in FIGS. 4 and 5 in parallel with a relay valve opening / closing control routine (not shown).
For example, the processor starts execution of the vehicle turning prevention routine each time an interrupt signal sent from the interrupt timer (not shown) built into the ECU 15 at a predetermined cycle is generated.

That is, when an interrupt signal is generated, the ECU
The processor of 15 first determines whether or not the rear wheel lock has occurred (step S1). Therefore, for example, the processor determines whether or not the ABS signal a3 sent from the ABS controller 31 is at the pressure reduction signal level, and the ABS signal
If the signal a3 has the pressure reduction signal level, it is determined that the rear wheels are locked. When the processor determines in step S1 that the rear wheel is not locked, the processor ends the vehicle rotation prevention routine in the current loop corresponding to the current interrupt signal without performing a substantial control operation.

On the other hand, if the rear wheels are locked, step S
When the determination is made in 1, the processor further determines whether or not the rear wheel brake is in the inoperative state (step S2). Therefore, for example, the processor determines whether a control signal for opening the rear-wheel relay valve is being sent from the processor to the rear-wheel relay valve, and if such a control signal is not being sent, Determine that the wheel brakes are inactive.

When it is determined in step S2 that the rear wheel brake is in the active state following the detection of the rear wheel lock state in step S1, the processor does not perform a substantial control operation and the vehicle in the loop this time is executed. The rotation prevention routine ends. In this way, when the rear wheel lock state occurs due to the operation of the rear wheel brake, the ABS controller 31 executes the normal ABS control. That is, ABS
The solenoid valve of the valve unit 11 is drive-controlled by the ABS controller 31 to remove the compressed air from the brake chambers 8 and 8'of the rear wheels to reduce the rear wheel braking force, thereby canceling the rear wheel lock state. become.

On the other hand, when it is determined in step S2 that the rear wheel brakes are inactive, the processor determines that the rear wheel lock state has occurred due to the operation of the retarder 103. If left as it is, the rear wheel lock causes the vehicle to rotate. Even if the retarder switch 140 is in the ON state, it is forcibly stopped sending the low level control output to the retarder drive circuit 130 (step S).
3).

Next, the processor determines whether or not vehicle turning has started based on the output signal from the lateral acceleration sensor 36 (FIG. 1) indicating the vehicle attitude (step S4).
If the result of this determination is negative, the vehicle rotation prevention routine in the current loop corresponding to the interrupt signal of this time is ended without further performing the actual control operation. On the other hand, when it is determined in step S4 that the vehicle rotation has started, the processor further determines whether or not it is right rotation (step S4).
5).

When it is determined in step S5 that the engine is rotating to the right, the processor sends a control signal for opening the relay valve of the right front wheel built in the ABS valve unit 10R to open the valve (step S5). S
6) Restart the timer built in the ECU 15 for measuring the braking force application time (step S7). At this time, the predetermined time Δt set in the timer is preset so as to prevent further vehicle turning, and the ECU 1
5 are stored in a predetermined memory area. Next, the processor determines whether or not the predetermined braking force application time Δt has passed by determining whether or not there is a timer output that is sent when the predetermined time Δt has passed since the start of the braking force application (step S8). ). When it is determined in step S8 that the predetermined braking force application time Δt has not yet elapsed, the processor waits for the predetermined time Δt to elapse. After that, when the predetermined time Δt elapses and the timer output is transmitted, the processor determines that further vehicle rotation is prevented, and terminates the transmission of the control signal to the relay valve for the right front wheel (step S9). ), This ends the vehicle turning prevention routine in the current loop.

When it is determined in step S5 that the engine is not right-handed and therefore left-handed, the processor opens the relay valve for the left front wheel built in the ABS valve unit 10L. A control signal for sending is sent (step S10), and the timer is restarted (step S11). Next, the processor determines whether or not the predetermined time Δt has elapsed (step S12), and waits for the predetermined time Δt to elapse if the predetermined time Δt has not yet elapsed. After that, when it is determined in step S12 that the predetermined time Δt has elapsed, the processor
Assuming that further vehicle rotation is prevented, the transmission of the control signal to the relay valve for the left front wheel is terminated (step S
13), thereby ending the vehicle rotation prevention routine in the current loop.

As described above, when the vehicle rotation starts due to the rear wheel lock due to the auxiliary brake operation, as a result of applying the braking force to one of the front wheels corresponding to the vehicle rotation direction, the action force for preventing the vehicle rotation from occurring. Is added to the vehicle body, and further vehicle rotation is prevented. On the other hand, since the braking force application is stopped immediately thereafter, the running stability and maneuverability of the vehicle are not impaired. Therefore, it is possible to reliably prevent the vehicle from easily turning due to the braking operation of the auxiliary brake such as the retarder while traveling on the low μ road.

Next, a vehicle turning prevention method according to a second embodiment of the present invention will be described. This embodiment is different from the above-described first embodiment in which a braking force is applied to one front wheel corresponding to the vehicle turning direction when the vehicle starts turning due to the rear wheel lock due to the auxiliary brake operation, at the time of detecting the vehicle turning start. The difference is that the front wheels are steered in the direction opposite to the turning direction.

For this reason, the vehicle to which the method of the second embodiment is applied has the same basic configuration as the vehicle shown in FIGS. 1 to 3, but, for example, a steering shaft having a worm shaft portion and this worm. A pulse motor rotationally coupled to the steering shaft via a worm gear and a reduction gear that are screwed to the shaft portion is provided. The vehicle to which the method of the second embodiment is applied basically operates in the same manner as in the case of the first embodiment. However, in the vehicle rotation prevention routine,
If it is determined that the rotation is right rotation, step S6 in FIG.
Instead of S9 to S9, the steering shaft is rotationally driven by the pulse motor so that the left and right front wheels are steered in the direction for turning the vehicle to the left, and then the steering shaft is returned to the neutral position. If it is determined that the vehicle is turning to the left, the steering shaft is rotationally driven so that the left and right front wheels are steered in the direction of turning the vehicle to the right instead of steps S10 to S13 of FIG. Returned to.

As described above, when the vehicle rotation starts due to the rear wheel lock due to the auxiliary brake operation, the front wheel is steered in the direction opposite to the vehicle rotation direction, and as a result, the action force that prevents the vehicle rotation is applied to the vehicle body. Further vehicle turning is prevented. On the other hand, since the front wheels are immediately returned to the straight traveling position, the running stability and maneuverability of the vehicle are not impaired. Therefore, as in the case of the first embodiment, it is possible to reliably prevent vehicle rotation that tends to occur with the braking operation of the auxiliary brake such as the retarder while traveling on the low μ road.

The vehicle turning prevention method of the present invention is not limited to the first and second embodiments described above, but can be variously modified. For example, although the present invention is applied to large vehicles such as buses and trucks in the first and second embodiments, the present invention can be applied to various vehicles including passenger cars. Further, in the embodiment, the vehicle equipped with the electronically controlled air brake system has been described, but the method of the present invention can be applied to the vehicle equipped with the air over hydraulic brake system and other brake systems. . Then, the vehicle to which the method of the present invention is applied can mount an ABS other than the three-channel ABS, and it is not essential to equip the ABS. An auxiliary braking device other than the hydraulic retarder can be mounted on the vehicle.

Furthermore, in the first and second embodiments described above, when it is determined in step S2 of FIG. 4 that the rear wheel brake is in the inoperative state, it is determined that the rear wheel lock state is caused by the operation of the retarder 103. However, such a determination may be made based on the on / off state of the retarder switch 140. Further, in the second embodiment, the steering shaft is rotationally driven by the motor to perform the front wheel steering for preventing the vehicle from turning, but the front wheel steering mechanism can be configured in various ways.
For example, a control valve arranged in the middle of a branch pipe provided in the power steering system may be controlled to open and close when the vehicle is turning to steer the front wheels, and then the front wheels may be returned to the straight traveling position.

[0037]

As described above, the vehicle rotation preventing method of the present invention determines whether the vehicle rotation has started when the rear wheels are locked due to the braking operation of the auxiliary brake device, and the vehicle rotation has started. At times, the braking force is applied to one of the front wheels corresponding to the vehicle turning direction, or the front wheels are steered in the direction opposite to the vehicle turning direction, so the vehicle is traveling on a road surface having a small friction coefficient. It is possible to prevent vehicle rotation that is likely to occur due to the braking operation of the auxiliary brake device.

[Brief description of drawings]

FIG. 1 is a diagram mainly showing a vehicle brake system to which a vehicle turning prevention method according to an embodiment of the present invention is applied.

2 is a schematic diagram showing a mounting portion of a hydraulic retarder mounted on a vehicle equipped with the brake system of FIG. 1. FIG.

FIG. 3 is a sectional view showing the hydraulic retarder of FIG. 2 in detail.

FIG. 4 is a flowchart showing a part of a vehicle turning prevention routine executed by the electronic control unit of FIG.

FIG. 5 is a flowchart showing the remaining part of the vehicle rotation prevention routine.

[Explanation of symbols]

 3 Brake valve 4 Brake pedal 7, 7 ', 8, 8' Brake chamber 10L, 10R, 11 ABS valve unit 15 Electronic control unit (ECU) 31 ABS controller 32, 33, 34 Wheel speed sensor 35 Vehicle speed sensor 103 Hydraulic retarder 121 electromagnetic clutch 130 retarder drive circuit 140 retarder switch

Claims (2)

[Claims] 1. When the rear wheels are locked due to the braking operation of the auxiliary brake device, it is determined whether or not vehicle turning has started. When vehicle turning starts, one of the front wheels is controlled to correspond to the vehicle turning direction. A method for preventing vehicle rotation, characterized by applying power. 2. It is determined whether or not vehicle turning has started when the rear wheels have locked due to the braking operation of the auxiliary braking device, and when the vehicle turning has begun, the front wheels are steered in a direction opposite to the vehicle turning direction. A method for preventing vehicle rotation, which is characterized by: