JP3269204B2 - Vehicle brake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake system for a vehicle, and more particularly to an automatic brake mechanism for automatically operating a brake in accordance with a distance to a forward obstacle to avoid a collision, and a wheel lock by an excessive braking force. The present invention relates to a vehicular brake device including both an anti-lock brake mechanism that suppresses pressure and improves steering performance.

[0002]

2. Description of the Related Art Conventionally, for the purpose of improving the safety of a vehicle, the front of the vehicle is monitored by a radar or the like, and a brake is automatically operated when an obstacle ahead and an own vehicle are unduly approached. Devices for avoiding collisions are known. If the brake device mounted on the vehicle has such a function, it is possible to prevent, for example, a driver's inattentive driving or careless collision from occurring beforehand, which is effective for improving safety.

Further, if the wheels are locked and the grip is lost while the vehicle is running, the wheels become locked due to excessive braking force in consideration of the vehicle becoming unstable due to the loss of steering function and the like. In such a case, an anti-lock brake system (ABS) having a mechanism for releasing the locked state by reducing the brake hydraulic pressure supplied to the brake mechanism has been widely used.

Japanese Patent Laying-Open No. 5-50908 discloses a vehicular brake device provided with both the above-mentioned automatic brake mechanism and ABS mechanism. This device is provided between a master cylinder that generates a brake oil pressure corresponding to the driver's brake pedal operation and a brake mechanism that is provided for each wheel so as to receive the brake oil pressure and exert the desired braking force. The ABS mechanism is interposed, and a brake oil pressure is supplied to the ABS mechanism from an automatic brake mechanism in addition to the master cylinder.

According to such a brake device, the brake oil pressure generated in the master cylinder drives the brake mechanism accurately in accordance with the driver's intention, and when the vehicle unduly approaches an obstacle ahead, Regardless of the driver's intention, the brake hydraulic pressure generated by the automatic brake mechanism drives the brake mechanism accurately to avoid a collision.

[0006] Regardless of whether the source of the brake hydraulic pressure is the master cylinder or the automatic brake mechanism, when the wheel is locked by excessive brake hydraulic pressure, the ABS mechanism operates to activate the brake. The hydraulic pressure is reduced, and deceleration is performed while maintaining a stable running state.

[0007]

However, the above-mentioned conventional brake device is based on the premise that the ABS mechanism always operates normally, and consideration is given to the behavior of the vehicle when the ABS mechanism is abnormal. Not something.

In other words, the automatic brake mechanism provided in the above-described conventional brake device continuously supplies a predetermined brake pressure to the brake mechanism when the vehicle approaches the obstacle in front of the vehicle, until the vehicle approaches the obstacle. Is what you do. Therefore, if the automatic brake mechanism is operated in a situation where the ABS mechanism does not function properly and the wheel is locked due to this, unless the improper approaching state with the obstacle ahead is released, the wheel is locked. A situation in which the state continues may occur.

As described above, the conventional brake device described above
It has the feature that extremely high safety can be ensured when both the automatic brake mechanism and the ABS mechanism are functioning normally, but the wheel lock state is continuously generated when the ABS mechanism does not function properly There was a problem that there was a case where it was done.

[0010] The present invention has been made in view of the above points, and when an abnormality of the ABS mechanism is detected, AB
An object of the present invention is to provide a vehicular brake device that can solve the above-described problem by operating an automatic brake mechanism to such an extent that a stable state can be maintained in a state where the S mechanism does not operate.

[0011]

FIG. 1 is a diagram showing the principle configuration of a vehicular brake device which achieves the above object. That is, as shown in FIG. 1, the above object monitors the distance to the obstacle ahead of the vehicle, and when it is detected that a safe distance is not secured, a predetermined brake oil pressure is applied to the brake mechanism 1 of the wheel. An automatic brake mechanism 2 to be supplied, and an anti-lock brake mechanism that monitors a locked state of the wheel and releases the locked state by reducing the brake hydraulic pressure supplied to the brake mechanism 1 when the locked state is detected during braking. An abnormality detecting means for detecting an abnormality of the anti-lock brake mechanism by monitoring an operation state of the anti-lock brake mechanism; and detecting the abnormality of the anti-lock brake mechanism by the abnormality detecting means. When an abnormality of the mechanism 3 is detected, the automatic brake mechanism 2 sets a brake hydraulic pressure to be supplied to the brake mechanism 1. This is achieved by a vehicular brake device including an abnormality treatment means 5 for reducing the constant pressure to a predetermined level.

[0012]

Further, in the vehicle brake device having the above structure, when the abnormality detecting means 4 detects an abnormality of the antilock brake mechanism 3, the abnormality treating means 5
It is also effective to adopt a configuration in which the operation of the automatic brake mechanism 2 is permitted only for the brake mechanism 1 arranged on the front wheel.

[0014]

In the vehicle brake system according to the present invention, when the anti-lock brake mechanism 3 is functioning normally, the automatic brake mechanism 2 operates when the vehicle approaches an obstacle ahead. A predetermined brake oil pressure is supplied to the engine. At this time, when the wheels provided with the brake mechanism 1 are locked, the state is detected by the anti-lock brake mechanism 3, and the brake oil pressure is reduced to release the locked state.

On the other hand, when the anti-lock brake mechanism 3 does not function normally, the condition is detected by the abnormality detecting means 4. Then, the set pressure of the brake oil pressure generated when the automatic brake mechanism 2 operates is reduced by the abnormality treatment means 5. For this reason, at the time of braking accompanying the operation of the automatic brake mechanism 2, the wheels are unlikely to be in the locked state, and even if the anti-lock brake mechanism 3 does not function normally, the stable state of the vehicle does not significantly deteriorate.

[0016]

Further, when the anti-lock brake mechanism 2 is abnormal, if the brake hydraulic pressure is supplied from the automatic brake mechanism 2 to only the brake mechanism 1 disposed on the front wheel, the automatic brake mechanism 2 Even if the anti-lock brake mechanism 3 does not operate normally at the time of the operation, at least the rear wheels will not be in a locked state,
The vehicle does not fall into a significantly unstable state irrespective of the abnormality of the antilock brake mechanism 3.

[0018]

FIG. 2 is an overall structural view of a vehicle brake system according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a hydraulic booster (hereinafter simply referred to as a booster), and reference numeral 12 denotes a tandem brake master cylinder (hereinafter simply referred to as a master cylinder). Hereinafter, the configurations of the booster 10 and the master cylinder 12 will be described with reference to FIG.

As shown in FIG. 3, the master cylinder 12 has a housing 14. A cylinder bore 16 is formed in the housing 14, and a first pressure piston 18 and a second pressure piston 20 are fitted in the cylinder bore 16 in a liquid-tight and slidable manner. As a result, a first pressurizing chamber 22 and a second pressurizing chamber 24 are formed in front (left side in the figure) of the pistons 18 and 20, respectively, and a hydraulic pressure is generated when the brake pedal 26 is depressed.

As shown in FIG. 2, the first pressurizing chamber 22 is provided with a proportioning bypass valve 28 by a liquid passage 27.
The second pressurizing chamber 24 is connected to the rear wheel cylinders 34, 36 of the respective brakes of the left and right rear wheels 30, 32 via the proportioning bypass valve 28 and the pressure increasing device 37 via the liquid passage 39. Each brake is connected to a front wheel cylinder 42, 44.

That is, the vehicle brake system of this embodiment is of a front-rear two-system type, and the wheel cylinders 34, 3
6, 42, and 44 correspond to the above-described brake mechanism 1. In this vehicle, the left and right rear wheels 30, 32 are drive wheels.

The proportioning bypass valve 28
When the hydraulic pressure is normally generated in both the front wheel system and the rear wheel system, the hydraulic pressure supplied to the rear wheel cylinders 34, 36 is compared with the hydraulic pressure supplied to the front wheel cylinders 42, 44. To reduce the pressure at a constant rate. on the other hand,
When the hydraulic pressure is no longer normally generated in the front wheel system, the hydraulic pressure generated in the first pressurizing chamber 22 is supplied to the rear wheel cylinders 34 and 36 without reducing the pressure.

The pressure increasing device 37 shown in FIG. 2 is a device for increasing the hydraulic pressure in the second pressurizing chamber 24 of the master cylinder 12 and supplying it to the front wheel cylinders 42 and 44.
Its role will be described later.

The booster 10 is provided integrally with the master cylinder 12. This booster 10 is disclosed in
The configuration is the same as that of the booster described in 149947. The configuration will be briefly described below.

As shown in FIG. 3, a power pressure chamber 62 is formed in a housing 60 of the booster 10, and when the input rod 64 and the reaction piston 66 are advanced by depressing the booster pedal 26, the forward movement thereof is performed. The spool 7 of the control valve 74 is provided by a link mechanism 72 including a first link 68 and a second link 70.
6 and the power pressure chamber 62 is
8 is switched to a state communicating with the accumulator 80.

As a result, the power pressure is supplied to the power pressure chamber 62 from the accumulator 80 and the power piston 82
Will be advanced. Then, the first and second pressurizing pistons 18, 20 of the master cylinder 12 are advanced, and the front and rear wheel cylinders 42, 44,
The hydraulic pressure is transmitted to 34 and 36. The advance of the reaction piston 66 stops at a position where the depression force of the brake pedal 26 and the reaction force balance, the spool 76 stops at a position where the power pressure chamber 62 is not communicated with the accumulator 80 or the reservoir 78, and the power pressure chamber 62 Is maintained in a state where power pressure is generated.

The accumulator 80 has a pump 92 in which the brake fluid in the reservoir 78 is driven by a motor 90.
Through the check valve 94. The hydraulic pressure of the accumulator 80 is kept within a certain range by controlling the start and stop of the motor 90 based on the output signal of the pressure sensor 96.

An abnormal decrease in the hydraulic pressure of the accumulator 80 is detected by the pressure switch 98, and the brake warning lamp is turned on and the buzzer is operated. The hydraulic pressure of the accumulator 80 is guarded by a relief valve 100 at an appropriate level.

The vehicular brake system of this embodiment performs antilock control based on the power pressure generated in the power pressure chamber 62. Therefore, as shown in FIG. 2, the pressure intensifier 37 and the front wheel cylinder 42,
Two electromagnetic directional control valves 110 and 112 are provided between the electromagnetic directional control valves 44 and 44. The electromagnetic directional control valves 110 and 112 are connected to the power pressure chamber 62 by the liquid passages 114, 116 and 118.
Are connected to the fluid passages 114 and 116, respectively.
122 are provided.

The electromagnetic hydraulic pressure control valves 120 and 122 are connected to the reservoir 78. The front wheel cylinders 42 and 44 are connected to the power pressure chamber 62 to increase the hydraulic pressure. Hydraulic pressure state to reduce the hydraulic pressure by communicating with
The state is switched to the holding state in which the liquid pressure is held.

An electromagnetic directional control valve 124 is provided in a portion of the liquid passage 27 between the proportioning bypass valve 28 and the rear wheel cylinders 34 and 26, and the electromagnetic directional control valve 124 and the rear wheel cylinders 34 and 26 are provided.
Electromagnetic pressure control valves 126 and 128 which are directional switching valves at three positions are provided between the control valve 36 and the valve 36. Electromagnetic directional valve 12
4 is connected to the power pressure chamber 62 by a liquid passage 130, and another electromagnetic directional control valve 132 is provided in the liquid passage 130.

The electromagnetic directional control valve 132 is connected to the accumulator 80 by a liquid passage 134, and these electromagnetic directional control valves 124 and 132 are used during antilock control.
, The rear wheel cylinders 34, 36 are connected to the power pressure chamber 62, and the wheel cylinder pressure is increased, decreased, and held by the electromagnetic hydraulic pressure control valves 126, 128.

The power intensifier 37 is supplied with power pressure through a liquid passage 140, and when the booster 10 normally generates power pressure, the second pressure chamber 24 and the front wheel cylinders 42, 44 are communicated. To supply the master cylinder hydraulic pressure to the front wheel cylinders 42, 44. On the other hand, in the event of a power pressure failure in which the booster 10 does not normally generate the power pressure, the pressure booster 37 cuts off the communication between the second pressurizing chamber 24 and the front wheel cylinders 42, 44 and uses the pressure boosting piston to stop the communication. The pressure in the second pressure chamber 24 is increased and supplied to the front wheel cylinders 42 and 44.

Further, a differential pressure switch 142 is provided between the chamber of the second pressure chamber 24 of the pressure increasing device 37 to which the liquid pressure is supplied and the liquid passage 140 to detect a power pressure failure. ECU
(Electronic control unit) 146 so that antilock control is not performed. Further, the liquid passage 14
0 is provided with a pressure limiter 144, and when the master cylinder fluid pressure is further increased after the power pressure reaches the defeat limit, the pressure limiter 144 brakes from the pressure intensifier 37 to the power pressure chamber 62. The backflow of the liquid is prevented so that the pressure increasing effect is not performed.

Left and right rear wheels 30, 32, which are driving wheels during acceleration
If the slip is excessive, the electromagnetic directional control valve 1
24, 132, the rear wheel cylinder 34,
36 is supplied with the hydraulic pressure of the accumulator 80, and the switching of the electromagnetic hydraulic pressure control valves 126 and 128 increases or decreases the wheel cylinder pressure, thereby eliminating the slip.

The antilock control and the acceleration slip control are performed by the ECU 146. Where EC
U146 is mainly composed of a computer, and detects the signals of the pressure sensor 96, the pressure switch 98, the differential pressure switch 142 and the rotational speeds of the left and right front wheels 38, 40 and the rear wheels 30, 32. Sensor 14
The wheel speed, the wheel deceleration, the vehicle speed, and the like are calculated based on the detection results of 8, 150, 152, and 153, and antilock control and acceleration slip control are performed based on the calculation results.

During the execution of the antilock control and the acceleration slip control, the rotation speed sensors 148, 150, 1
By monitoring the states of 52 and 153, it is determined whether or not normal control has been executed. That is, in the present embodiment, the ECU 146 and the rotation speed sensors 148, 1
Reference numerals 50, 152, and 153 realize the above-described abnormality detecting means 4.

A liquid passage 27 connecting the first pressurizing chamber 22 and the proportioning bypass valve 28, a liquid passage 39 connecting the second pressurizing chamber 24 and the proportioning bypass valve 28, and an electromagnetic directional control valve 132. The liquid pressure controlled by the spool-type electromagnetic hydraulic pressure control valve 160 is supplied to the liquid passages 130 connecting the power pressure chamber 62 through the liquid passages 154, 156, and 158, respectively.

The spool type electromagnetic hydraulic pressure control valve 160 is a valve which controls the hydraulic pressure of the accumulator 80 to a level proportional to the supply current and supplies the hydraulic pressure, and is known from Japanese Utility Model Laid-Open No. 63-40270. Hereinafter, the configuration will be briefly described with reference to FIG.

As shown in FIG. 4, the spool type electromagnetic hydraulic pressure control valve 160 has a valve hole 16 formed in a housing 162.
4 is fitted with a spool 168 so as to be substantially liquid-tight and slidable. By the movement of the spool 168, the spool type electromagnetic hydraulic control valve 160 connects the control pressure port 170 connected to the wheel cylinder to the low pressure port 172 connected to the reservoir 78 via the annular chamber 174 and the annular groove 176. Communication with the wheel cylinder to reduce the hydraulic pressure,
A state in which the high-pressure port 178 connected to the accumulator 80 is communicated with the high-pressure port 178 through the annular chamber 174 and the annular groove 180 to increase the wheel cylinder hydraulic pressure; Switch to.

A reaction force pin 18 is provided at one end of the spool 168.
4 is urged by a spring 186 and is brought into contact therewith. The reaction force pin 184 receives the hydraulic pressure of the control pressure port 170 supplied by the liquid passage 188 and applies an operating force based on the hydraulic pressure to the spool 168 to cut off the communication between the high pressure port 178 and the control pressure port 170. Generates operating force in the direction.

Further, a control force is applied to the spool 168 by the force motor 192 in a direction opposite to the above-described operation force and in a direction for communicating the control pressure port 170 and the high pressure port 178. The force motor 192 is provided in an air chamber 196 partitioned by a diaphragm 194 provided between the spool 168 and the housing 162. When the exciting current is not supplied to the exciting coil 198, the force motor 192 is attached to the force motor 192. The state shown in FIG. 4 is maintained by the force and the spool 168 is connected to the control pressure port 17.
0 is connected to the low pressure port 172.

When an exciting current is supplied to the exciting coil 198, the exciting coil 198 is pushed out of the yoke 202 by the magnetic field of the permanent magnet 200. Excitation coil 19
8, the spool 168 receives a control force opposite to the operation force of the reaction force pin 184, and the spool 168 stops at a position where the operation force and the control force are balanced. Is controlled to a pressure corresponding to the current supplied to the exciting coil 198.

Such a spool type electromagnetic hydraulic control valve 16
Change valves 210, 212, and 214 are provided at connection portions between the liquid passages 154, 156, and 158 for transmitting the control pressure of 0 and the liquid passages 27, 39, and 130, respectively. The hydraulic pressure supplied from the pressure chambers 22 and 24 and the power pressure chamber 62 and the spool type electromagnetic hydraulic control valve 160
And the higher hydraulic pressure is selected from the electric control hydraulic pressure supplied by the controller and supplied to the rear wheel cylinders, and the front wheel cylinders,.

These change valves 210, 212, 2
14 are the same, the change valve 210 will be representatively described. As shown in FIG.
A through hole 222 penetrating in the longitudinal direction is formed in the housing 220 of the change valve 210, the sleeve 223 is fitted in a liquid-tight manner, and both ends of the through hole 222 are closed by plugs 224 and 226, and the valve hole 228 is formed. Is formed, and the spool 230 is fitted movably in the axial direction.

A land 232 is formed at an intermediate portion in the longitudinal direction of the spool 230, and is fitted into the valve hole 228.
Thereby, on one side of the land 232, a master cylinder pressure chamber 236 connected to the first pressure chamber 22 of the master cylinder 12 by a port 234 formed in the plug 224.
Is formed, and a plug 226 is formed on the other side of the land 232.
An electric control hydraulic pressure chamber 240 connected to the spool-type electromagnetic hydraulic pressure control valve 160 is formed by a port 238 formed in the hydraulic pressure control valve 160. The change valve 214 is connected to the port 23
4 is connected to the power pressure chamber 62, and a power pressure chamber is formed on one side of the land 232.

Further, rubber valve members 244 and 246 are attached to both ends of the spool 230 in the longitudinal direction, and the valve members 244 and 246 and the land 23 are attached to the spool 230.
2, guides 248 and 250 having a large diameter are formed, and are fitted in the valve holes 228 to guide the movement of the spool 230. A plurality of grooves extending in the axial direction are formed on the outer peripheral surfaces of these guides 248 and 250 to allow the flow of the brake fluid.

An annular groove 254 is formed in a portion of the sleeve 223 corresponding to the land 232 on the inner peripheral surface forming the valve hole 228, and the ports 256, 258 are formed.
Are connected to the rear wheel cylinders 34 and 36. The land 232 is connected to the valve member 244 of the spool 230.
One of the ports 246 is seated at the open ends of the ports 234 and 238, and the ports 234 and 238 are connected to the master cylinder pressure chamber 23.
6. When one of the communication with the electric control hydraulic chamber 240 is interrupted, the communication between the interrupted chamber and the ports 256 and 258 is interrupted, and the uninterrupted chamber and the port 25 are interrupted.
6,258 is allowed.

The change valve 210 is always in the state shown in FIG. 5, and connects the first pressurizing chamber 22 of the master cylinder 12 with the rear wheel cylinders 34, 36. In a state where the electric control hydraulic pressure is not supplied from the spool type electromagnetic hydraulic control valve 160, the master cylinder hydraulic pressure is supplied to the rear wheel cylinders 34 and 36.

Here, the spool type electromagnetic hydraulic control valve 160
When the electric control hydraulic pressure is supplied from the first pressurizing chamber 22, and the master cylinder hydraulic pressure is not supplied from the first pressurizing chamber 22 or the master cylinder hydraulic pressure is lower even if it is supplied, the spool 230 is moved to the position shown in FIG. It will be moved to the left.

As a result, the brake fluid flows into the electric control hydraulic pressure chamber 240, and the pressure of the brake fluid is increased from the right side in the drawing to the land 2.
32 to move the spool 230 further to the left,
The valve member 244 is seated in the opening of the port 234 to cut off the communication between the first pressurizing chamber 22 and the rear wheel cylinders 34, 36. Then, the electric control hydraulic pressure chamber 240 communicates with the rear wheel cylinders 34, 36, and the electric control hydraulic pressure is supplied to the rear wheel cylinders 34, 36.

The change valves 210, 21
A normally closed electromagnetic on-off valve 270 is provided between the spool hydraulic pressure control valve 2214 and the spool type electromagnetic hydraulic pressure control valve 160 as shown in FIG. And these spool type electromagnetic hydraulic pressure control valves 1
60 and the solenoid on-off valve 270 are driven by a hydraulic pressure controller 274 which is a main part of the present embodiment.
It is controlled via 78.

That is, the controller 274 includes an EC
Vehicle speed information and fault information relating to antilock control and acceleration slip control are supplied from U146, and an inter-vehicle distance detection device 28 including a radar for monitoring the front of the vehicle.
From 0, distance information to an obstacle existing in front of the vehicle is supplied.

Then, the controller 274 appropriately controls the spool type electromagnetic hydraulic pressure control valve 160 and the electromagnetic on-off valve 270 based on the information in accordance with a routine described later.
The warning device 282 gives a necessary warning to the driver. In this sense, in this embodiment, the controller 274 implements the above-described automatic brake mechanism 2 and abnormality treatment unit 5.

Next, the operation of the vehicle brake device having the above configuration will be described.

When the vehicle brake system of this embodiment is in the non-braking state, the electromagnetic directional control valves 110, 112, 12
4, 132, electromagnetic hydraulic pressure control valves 120, 122, 126,
128, the solenoids of the solenoid on-off valve 270 are both demagnetized, and the change valves 210 and 212 are in the state shown in FIG. 5, and the master cylinder hydraulic pressure generated in the first and second pressurizing chambers 22 and 24 is controlled by the wheel cylinder. 34, 36, 42,
44. Also, no current is supplied to the spool type electromagnetic hydraulic pressure control valve 160,
0 is in communication with the reservoir 78.

If the brake pedal 26 is depressed during braking, the master cylinder hydraulic pressure is supplied to the front and rear wheel cylinders 34, 36, 42, 44, and the rotation of the wheels is suppressed.

Here, if the depression force of the brake pedal 26 becomes excessive with respect to the coefficient of friction of the road surface and the slip state of the wheel exceeds an appropriate state, a known anti-lock control is performed. That is, the electromagnetic direction switching valves 110, 112, 12
4, 132, the power pressure is supplied to the front and rear wheel cylinders 34, 36, 42, 44, respectively.
0, 122, 126, and 128 are first switched to the depressurized state, and the front and rear wheel cylinders 3
The brake fluid in 4,36,42,44 is drained to reservoir 78.

As a result, when the rotation of the wheels recovers, the electromagnetic hydraulic pressure control valves 120, 122, 126, and 128 are kept in the holding state. , 122, 126, 128
Are switched to a pressure reduction state, a holding state, and a pressure increase state, respectively, whereby the wheel slip ratio is maintained in an appropriate range.

As described above, in the present embodiment, the electromagnetic directional control valves 110, 112, 124, 132, the electromagnetic hydraulic pressure control valves 120, 122, 126, 128, and the ECU 146 for appropriately driving these valves are provided by the above-described anti-static valve. An ABS mechanism corresponding to the lock brake mechanism 3 is realized.

When the driving force is excessive during the acceleration of the oscillation of the vehicle and the slip of the right and left rear wheels 30, 32 is excessive, a known slip control is performed. That is, the hydraulic pressure of the accumulator 80 is supplied to the rear wheel cylinders 34 and 36 by the switching of the electromagnetic switching valves 124 and 132, and the electromagnetic hydraulic pressure control valves 126 and 128 are respectively in the pressure increasing state. By switching between the holding state and the reduced pressure state, the rotation of the wheels is appropriately suppressed.

On the other hand, when the distance to the obstacle ahead detected by the inter-vehicle distance detecting device 280 is unduly short as judged from the relative speed of the obstacle and the vehicle, the function as an automatic brake is exhibited. Appropriate control signals are issued from the controller 274 to the drive circuits 276 and 278. As a result, each change valve 210, 212, 2
Appropriate electric control hydraulic pressure is supplied to 14 via an accumulator 80.

At this time, if the brake pedal 26 is depressed and the master cylinder hydraulic pressure higher than the electric control hydraulic pressure is generated in the change valves 210, 212, 214, the wheel cylinders 34, 36, 42, 44 Is supplied with the master cylinder pressure.

When the electric control fluid pressure is higher than the master cylinder fluid pressure or when the brake pedal 26 is not depressed, the electric control fluid pressure becomes higher than that of the wheel cylinder 34,
Thus, the wheel cylinders 34, 36, 42, and 44 exert braking force in accordance with the supplied electric control fluid pressure regardless of the master cylinder pressure.

The vehicle brake device of the present embodiment exhibits the function as an automatic brake in this way. In this sense, in the present embodiment, the motor 90 and the pump 92, which are hydraulic pressure generating sources, and the spool type electromagnetic hydraulic pressure control valve 16 which converts and supplies this hydraulic pressure to a desired electric control hydraulic pressure
0, the electromagnetic on-off valve 270, the controller 274, the drive circuits 276, 278, and the following distance detection device 280 correspond to the automatic brake mechanism 2.

Incidentally, the spool type electromagnetic hydraulic control valve 16
0, the electric control hydraulic pressure is changed by the change valves 210, 21
2, 214, each wheel cylinder 34, 3 as long as the electric control hydraulic pressure exceeds the master cylinder pressure.
6, 42 and 44 are supplied with the electric control hydraulic pressure.

The electric control hydraulic pressure is a brake oil pressure calculated by the controller 274 to obtain a braking force necessary to avoid a collision between the vehicle and an obstacle in front of the vehicle. Is to be continuously supplied while maintaining a predetermined pressure until is released.

At this time, the electric control hydraulic pressure calculated by the controller 274 is used as the brake oil pressure as the wheel cylinders 34, 36, 42, 44 depending on the road surface conditions while the vehicle is running.
Is supplied to the wheels, the wheels may be locked due to the braking force generated due to this.

In this case, the electromagnetic direction switching valves 110 and 11
2, 124, 132, electromagnetic hydraulic pressure control valves 120, 122,
If the ABS mechanism consisting of 126 and 128 and the ECU 146 functions properly and antilock control is executed, the locked state of the wheels is appropriately released, and stable behavior during braking is maintained.

However, if an abnormality occurs in the ABS mechanism and the antilock control is not executed normally, and if no measures are taken, the lock state caused by the operation of the automatic brake is released and the electric control hydraulic pressure is subsequently released. Until the collision with the obstacle in front is avoided, and the unstable state is maintained for a long period of time.

The vehicle brake system according to the present embodiment is characterized in that it has an abnormality handling function corresponding to a failure of the ABS mechanism in order to prevent such a situation from occurring. Hereinafter, with reference to FIG . 6 and FIG. 7 , a description will be given of the content of the processing executed by the controller 274 so as to exert such a function.

FIG. 6 shows a flowchart of a first example of a routine executed by the controller 274. The routine shown in the figure reduces the maximum brake oil pressure during automatic brake operation, that is, the set pressure of the electric control hydraulic pressure in comparison with the normal operation, in consideration of the possibility that the wheels may be locked when the ABS mechanism fails. This is a routine for performing a treatment.

In order to realize such measures, when the routine is started, it is first determined in step 100 whether or not the ABS mechanism has a failure based on the failure information supplied from the ECU 146. This is because if the ABS mechanism is functioning normally, no action needs to be taken.

If it is determined that the ABS mechanism is out of order, that is, the ABS mechanism is not functioning normally in response to the command from the ECU 146, then step 10 is executed.
Proceed to 2 to correct the timing for issuing the inter-vehicle distance warning.

In the vehicle brake device of this embodiment, the warning device 282 gives a warning to the driver about the abnormal approach before the automatic brake is activated when the vehicle approaches the obstacle ahead of the vehicle. When the ABS mechanism is out of order, it is necessary to start the automatic brake operation earlier than in the normal state because the maximum braking force by the automatic brake is suppressed as described later. This is because it is necessary to make correction earlier.

After the correction process has been executed, the routine proceeds to step 104, where the brake hydraulic pressure for automatic braking, that is, the above-mentioned maximum set pressure of the electric control hydraulic pressure is reduced and corrected. This is to prevent the wheel from being locked during the automatic braking operation as described above. Incidentally, in this routine, this step 104 corresponds to the abnormality treatment means 5 described above.

As described above, the above steps 100 to 10
After the process of step 4 is executed, it is next determined in step 106 whether the following distance is abnormal based on the detection result of the following distance detecting device 280. Here, the determination as to whether or not there is an abnormality is made based on a predetermined distance set corresponding to the timing at which an alarm should be issued. That is, when the ABS mechanism is out of order, a longer inter-vehicle distance is determined to be abnormal as compared to when the ABS mechanism is functioning normally.

If it is determined in step 106 that the inter-vehicle distance is abnormal, that is, that the vehicle is abnormally approaching the obstacle ahead, step 108
Then, an inter-vehicle distance abnormality alarm is issued by the alarm device 282, and in step 110, an automatic brake is operated to exert an appropriate braking force, and the current process is terminated.

That is, when the controller 274 executes this routine, when the ABS mechanism is functioning normally, the automatic brake is operated with a large braking force. If measures are taken by the lock control, while the ABS mechanism is malfunctioning, a collision will be avoided by operating the automatic brake from an early stage with a braking force that does not lock the wheels in advance. .

As described above, according to the vehicle brake device of the present embodiment, even if the automatic brake is operated in a situation where the ABS mechanism is abnormal, the wheels are locked and become unstable during the operation. It does not induce any unusual behavior, and can always reliably and reliably exhibit the collision prevention function by automatic braking.

[0081]

[0082]

[0083]

[0084]

[0085]

FIG . 7 shows that the controller 274 operates in the ABS mode.
9 shows a flowchart of a third example of a routine executed to take an abnormal action for a mechanism failure. This routine is
When the ABS mechanism is abnormal, a remarkable change in behavior is prevented by exerting the braking force by the automatic brake only on the front wheels. That is, the routine shown in FIG.
And failure of the ABS mechanism as in the routine shown in FIG.
Is determined (step 300), and a failure is detected.
If not, leave it as it is, and if a failure is detected,
After correcting the timing for issuing the following distance warning (S
(Step 302), determine whether or not an inter-vehicle distance abnormality has occurred.
Another operation is performed (step 306). And the inter-vehicle distance abnormality
If so, an alarm 282 informs the situation.
A warning is given to the diverted person to call attention (step 308). Since then
Determine again whether the ABS function has failed
(Step 310), and if it is normal, lock the wheel.
Activate the automatic brake because there is no worry (step 31
2).

On the other hand, when a failure of the ABS mechanism is detected
(Step 310) is characterized in that only the two front wheels exert the braking force due to the automatic braking (Step 314).

In this case, even if the ABS mechanism has failed, at least the two rear wheels are not locked when the automatic brake is actuated, and even if the braking force by the automatic brake is excessive, the vehicle may not be locked. Extremely unstable conditions can be prevented.

When the controller 274 executes this routine, the braking force by the automatic brake is exerted only on the two front wheels when the ABS mechanism fails, so that the braking distance is longer than in the normal state. However, as in the routine shown in FIG. 6, the processing of steps 302 and 306 in this routine corrects the operation start timing of the automatic brake earlier in the event of the ABS mechanism failure than in the normal state. Will be demonstrated.

[0090]

As described above, according to the first aspect of the present invention, when an abnormality occurs in the anti-lock brake mechanism of the vehicle brake device and a normal function cannot be exhibited, the wheels are locked by excessive braking force. In order to prevent the state, the automatic brake mechanism supplies a brake hydraulic pressure which is reduced compared to the normal state.

Therefore, even when the anti-lock brake mechanism is functioning normally and the anti-lock brake mechanism is not functioning properly due to the occurrence of an abnormality in the anti-lock brake mechanism, the wheel is not operated when the automatic brake is activated. Is unlikely to be in a locked state, and higher safety can be ensured as compared with a conventional vehicle brake device that does not have such an abnormal action function.

[0092]

When the anti-lock brake mechanism does not function normally, the brake hydraulic pressure generated by the automatic brake mechanism is supplied only to the brake mechanism provided on the front wheels. For this reason, even if the anti-lock brake mechanism does not function, the rear wheel does not become locked when the automatic brake is actuated, and the anti-lock brake mechanism has a higher function than a conventional vehicle brake device that does not have such an abnormal action function. It has the feature that high running stability can be maintained in abnormal situations.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a vehicle brake device according to the present invention.

FIG. 2 is an overall configuration diagram of a vehicle brake device according to an embodiment of the present invention.

FIG. 3 is a side sectional view illustrating a configuration of a hydraulic booster and a master cylinder of the vehicle brake device according to the present embodiment.

FIG. 4 is a side sectional view illustrating a configuration of a spool type electro-hydraulic pressure control valve of the vehicle brake device according to the present embodiment.

FIG. 5 is a side sectional view illustrating a configuration of a change valve of the vehicle brake device according to the present embodiment.

FIG. 6 is a flowchart of a first example of a routine executed by a controller of the vehicle brake device of the present embodiment.

FIG. 7 is a controller of the vehicle brake device according to the embodiment .
9 is a flowchart of a third example of a routine executed by the user.
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[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake mechanism 2 Automatic brake mechanism 3 Anti-lock brake mechanism 4 Abnormality detection means 5 Abnormality treatment means 34, 36, 42, 44 Wheel cylinder 90 Motor 92 Pump 110, 112, 124, 132 Electromagnetic direction switching valve 120, 122, 126, 128 Electromagnetic hydraulic pressure control valve 146 ECU 148, 150, 152, 153 Rotation speed sensor 160 Spool type electromagnetic hydraulic pressure control valve 270 Electromagnetic on-off valve 274 Controller 276, 278 Drive circuit 280 Distance between vehicles detection device

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T 8/92 B60T 7/12

Claims (1)

(57) [Claims] 1. The system monitors the distance to an obstacle in front of the vehicle, and
If it detects that the correct distance is not secured,
A self-supply system that supplies a predetermined brake oil pressure to the brake mechanism
A dynamic brake mechanism and monitors the locked state of the wheels, and detects the locked state during braking.
If detected, the vibration supplied to the brake mechanism is
Anti-lock to release the locked state by reducing the hydraulic pressure
A brake mechanism for a vehicle, comprising: a brake mechanism for monitoring an operation state of the antilock brake mechanism.
Detect the abnormality of the antilock brake mechanism
Abnormality detection means, and the abnormality detection means
When an abnormality is detected, the automatic braking mechanism
Set the brake oil pressure supplied to the brake mechanism to
Abnormality treatment means to reduce the pressure to the level ofWith And the abnormality detecting means is the anti-lock brake machine.
When detecting a structural abnormality, the abnormality treating means
Operation of the automatic brake mechanism only for the front wheels of the wheels
Allow A vehicle brake device characterized by the above-mentioned.