JPH04362451A - Vehicle collision preventive device - Google Patents

Abstract

PURPOSE:To enable more precise automatic braking control by taking into consideration time required by judgement to avoid collision and time required for an actuator to start operating. CONSTITUTION:A reference distance LR which will be a reference for avoiding collision, is found from the following equation: LR=VV.(TD+ TX)+(VV<2>-VB<2>)/(2alpha), where VV is vehicle speed, L is distance to a subject obstruction, TD is time required for an actuator to start operating in response to output signals from a control circuit 54, TX is time required from signal input to signal output within the control circuit 54, alpha is the set deceleration of a vehicle, and VD is the running speed of the subject obstruction which is found by the following equation: VB=VV+dL/dt.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a vehicle body speed detector for detecting the vehicle body speed of a vehicle, a distance detector for detecting the distance of the vehicle to a reference obstacle, and a vehicle body speed detector for detecting the vehicle body speed of the vehicle, a distance detector for detecting the distance of the vehicle to a reference obstacle, and a collision avoidance with the reference obstacle. an actuator that performs a necessary operation; a reference distance to the reference obstacle is calculated based on the vehicle speed and distance; and the actuator is operated in response to a predetermined relationship between the reference distance and the distance. The present invention relates to a vehicle collision prevention device including a control circuit that outputs a signal for activation.

0002

2. Description of the Related Art Conventionally, such a collision prevention device is known from, for example, Japanese Patent Publication No. 61-4700.

0003

[Problem to be solved by the invention] In the above conventional method,
Let the relative distance between the vehicle and the vehicle ahead of the vehicle be L, the relative speed between them be (dL/dt), and assume that the vehicle decelerates at a constant deceleration α, the control circuit calculates L< {
(dL/dt)2/(2α)} is determined, and when it is determined that the formula is satisfied, a signal for automatically applying the brake is output from the control circuit.

However, the time it takes for the control circuit to calculate the inequality and decide whether to apply the automatic brake, and the time it takes for the actuator to actually start operating in response to the signal output from the control circuit. For example, it takes about 0.5 to 1.0 seconds in total, but
The above-mentioned conventional system does not take this time into consideration, and it is difficult to say that accurate automatic braking control for collision prevention is executed.

The present invention has been made in view of the above circumstances, and provides more precise automatic braking control in consideration of the time required to determine whether collision avoidance should be performed and the time required to start actuator operation. The purpose of the present invention is to provide a vehicle collision prevention device that enables the following.

[0006]

[Means for Solving the Problems] In order to achieve the above object, according to a first feature of the present invention, the vehicle body speed (V
V), a distance detector that detects the distance (L) of the vehicle to the reference obstacle, an actuator that performs necessary operations to avoid collision with the reference obstacle, and the vehicle body. Velocity (VV) and distance (L
) based on the reference distance to the reference obstacle (LR)
and a control circuit that calculates the reference distance (LR) and the distance (L) and outputs a signal for operating the actuator when the reference distance (LR) and the distance (L) meet a predetermined relationship. In the control circuit, LR=VV・(TD+TX)+(
VV 2 −VB 2 )/(2α) where TD; Time TX until the actuator starts operating in response to a signal output from the control circuit; Time α required from signal input to signal output in the control circuit; Set deceleration VB: The traveling speed of the reference obstacle, which is calculated by the following equation. The reference distance (LR) is calculated according to the following equation: VB = VV + dL/dt.

According to a second feature of the present invention, the control circuit is arranged such that a plurality of reference distances calculated based on a plurality of predetermined decelerations and the distances each have a predetermined relationship. Sometimes, the actuator is configured to output signals for causing the actuator to perform mutually different operations.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a diagram of a fluid pressure system for braking a vehicle, and FIG.
3 is a longitudinal sectional view of the electric fluid pressure output means, FIG. 3 is a longitudinal sectional view of the fail-safe electromagnetic switching valve, FIG. 4 is a block diagram showing the schematic configuration of the electronic control unit, and FIG. 5 is the schematic configuration of the autobrake control circuit. FIG.

First, in FIG. 1, the front axle 1F of a passenger vehicle
Left front wheel WFL and right front wheel WFR on both sides of
is equipped with a left front wheel disc brake BFL and a right front wheel disc brake BFR, and a left rear wheel WRL and a right rear wheel WRR on both sides of the rear axle 1R are equipped with a left rear wheel disc brake BRL and a right rear wheel disc brake. BRR is installed. The braking device of the vehicle includes a left fluid pressure system LL, a right fluid pressure system LR, and a collective fluid pressure system LT, in which the left fluid pressure system LL
is configured such that the electric fluid pressure output means AFL for the left front wheel and the first output port 2 of the tandem type master cylinder M are switchably connected to the disc brake BFL for the left front wheel. The electric fluid pressure output means AFR for the rear wheel and the second output port 3 of the tandem master cylinder M are switchably connected to the right front wheel disc brake BFR. The pressure output means AR is connected to the left and right rear wheel disc brakes BRL and BRR.

In FIG. 2, the electric fluid pressure output means AFL for the front left wheel is coaxially connected to a cylinder body 4 formed into a bottomed cylindrical shape with a closed end on the front end side, and a rear end of the cylinder body 4. a guide tube 5, a support tube 6 coaxially connected to the guide tube 5, a connection tube 7 coaxially connected to the support tube 6, and an encoder 8 coaxially connected to the connection tube 7. A piston 11 is slidably fitted into the cylinder body 4 with a pressure chamber 10 formed between the motor 9FL and the closed end of the cylinder body 4, and a piston 11 is prevented from rotating around its axis and is guided. A cylindrical nut member 12 is disposed within the cylinder 5 and coaxially connected to the rear end of the piston 11, and an Oldham nut member 12 is connected to the nut member 12 via a ball screw 13 and is connected to the output shaft 9a of the motor 9FL. joint 14
The rotating shaft 15 is connected to the rotating shaft 15 via the rotating shaft 15.

A plurality of grooves 16 and 17 extending in the axial direction are provided on the inner surface of the guide tube 5 and on the outer surface of the nut member 12, and the grooves 16 and 17 correspond to each other.
By fitting the balls 18 into the respective holes, the nut member 12, that is, the piston 11, is prevented from rotating around the axis. Further, the rotating shaft 15 is rotatably supported by the support tube 6 via a pair of ball bearings 19 and 20, and a collar 21 that extends outward in the radial direction and is provided on the rotating shaft 15, as well as a collar 21 provided on the rotating shaft 15, The retaining rings 22 fitted in the ball bearings 19 and 20 respectively engage with the axially outer ends of the inner rings of the ball bearings 19 and 20, thereby preventing the rotary shaft 15 from moving in the axial direction.

[0013] Also, in the upper part of the cylinder body 4, a pressure chamber 10 is provided.
A reservoir 23 is provided to allow replenishment of working fluid to and return of working fluid from the pressure chamber 10. Furthermore, the cylinder body 4 has an output port 24 communicating with the pressure chamber 10.
FL is provided, and the output port 24FL is connected to the left fluid pressure system LL. Moreover, at the closed end of the cylinder body 4, there is a left-hand valve for detecting the fluid pressure in the pressure chamber 10, that is, the braking pressure of the left-front disc brake BFL when the output port 24FL is in communication with the left-front disc brake BFL. A front wheel pressure sensor SFL is installed.

In the electric fluid pressure output means AFL for the left front wheel, the piston 11 is caused to reciprocate in the axial direction by the ball screw 13 in response to the forward and reverse rotation of the motor 9FL, and the corresponding fluid pressure is This will occur in room 10.

The electric fluid pressure output means AFR for the right front wheel and the electric fluid pressure output means AR for the rear wheel basically have the same configuration as the electric fluid pressure output means AFL for the left front wheel. Although a detailed explanation will be omitted, in the electric fluid pressure output means AFR for the right front wheel, fluid pressure corresponding to the amount of rotational operation of the motor 9FR is output from the output port 24FR, and the fluid pressure is transmitted to the right front wheel pressure sensor SFR. The rear wheel electric fluid pressure output means AR outputs fluid pressure corresponding to the amount of rotation of the motor 9R to the output port 24R.
The fluid pressure is detected by the rear wheel pressure sensor SR.

Referring again to FIG. 1, the tandem type master cylinder M is a conventionally known type that outputs fluid pressure from the first and second output ports 2 and 3 according to the amount of depression of the brake pedal 26. The type master cylinder M is attached with a stroke sensor SS that detects the pedal stroke of the brake pedal 26 and a pressure sensor SM that detects the output fluid pressure from the first output port 2 corresponding to the depression force of the brake pedal 26. .

A fail-safe electromagnetic switching valve 27L is interposed in the left fluid pressure system LL, and this electromagnetic switching valve 27L connects the output port 24FL of the electric fluid pressure output means AFL for the left front wheel when the solenoid 36L is energized. is connected to the left front wheel disc brake BFL, and the first output port 2 of the master cylinder M is connected to the accumulator AC.
and the output port 24F of the electric fluid pressure output means AFL for the left front wheel when the solenoid 36L is demagnetized.
It is possible to switch between a state in which the first output port 2 of the master cylinder M is communicated with the front left wheel disc brake BFL and the first output port 2 of the master cylinder M is disconnected from the front left wheel disc brake BFL.

In FIG. 3, the fail-safe electromagnetic switching valve 27L has a first input port 28 communicating with the output port 24FL of the electric fluid pressure output means AFL for the left front wheel, and a first input port 28 communicating with the first output port 2 of the master cylinder M. 2 input port 29, the first leading to the left front wheel disc brake BFL
a housing 32 having an output port 30 and a second output port 31 communicating with the accumulator AC; first and second disc-shaped valve bodies 33 coaxially interlocked and connected and slidably connected within the housing 32; 34, a return spring 35 interposed between the second valve body 34 and the housing 32 to exert a spring force that urges both the valve bodies 33, 34 to one side in the axial direction, and a spring of the return spring 35 when energized. A solenoid 36L is housed in the housing 32 to exert an electromagnetic force that attracts both the valve bodies 33 and 34 to the other side in the axial direction against the force.
Equipped with.

The first and second valve bodies 33 and 34 are connected to the connecting shaft 3.
They are coaxially connected by 7. Also, on the outer surface of the first valve body 33, there is a solenoid 36L, which communicates with the first output port 30 as shown by the solid line in FIG. 3 when the solenoid 36L is energized.
When L is demagnetized, the annular groove 38 that is disconnected from the first output port 30 connects to the first input port 28, as shown by the broken line in FIG.
It is installed in such a way that it is in constant communication with the Furthermore, the distance between the first and second valve bodies 33 and 34 is determined by the solenoid 36L.
When the 2nd input port 2 is energized, as shown by the solid line in Fig.
9 and the first output port 30 with the first valve body 33, and the second input port 29 and the second output port 3
When the solenoid 36L is demagnetized, the first input port 29 and the second output port 31 are disconnected by the second valve body 34 as shown by the broken line in FIG. The ports 30 are set to communicate with each other.

[0020] This fail-safe electromagnetic switching valve 27L
The solenoid 36L is energized in response to the start of the engine installed in the vehicle. Normally, the solenoid 36L is in an energized state and outputs the output fluid pressure of the electric fluid pressure output means AFL for the left front wheel. The output pressure of the master cylinder M is absorbed by the accumulator AC. Further, when the solenoid 36L is demagnetized, the electromagnetic switching valve 27L becomes capable of transmitting the output fluid pressure of the master cylinder M to the left front wheel disc brake BFL. Therefore, in the event of a failure in the electric fluid pressure output means AFL for the front left wheel, by demagnetizing the solenoid 36L of the fail-safe electromagnetic switching valve 27L, the output pressure of the master cylinder M is applied to the disc brake BFL for the left front wheel to exert a braking force. It is possible to ensure that

A fail-safe electromagnetic switching valve 27R having basically the same configuration as the fail-safe electromagnetic switching valve 27L is interposed in the right fluid pressure system LR, and this electromagnetic switching valve 27R has a solenoid 36R. When energized, the output port 24FR of the electric fluid pressure output means AFR for the right front wheel is communicated with the disc brake BFR for the right front wheel, and the second output port 3 of the master cylinder M is communicated with the accumulator AC common to the electromagnetic switching valve 27FL. When the solenoid 36R is in a state of It is possible to switch between the state of communication with the BFR and the state of communication with the BFR.

A shutoff valve 40 is provided in the integrated fluid pressure system LT. This shutoff valve 40 is a neutral valve that can transmit the fluid pressure output from the output port 24R of the rear wheel electric fluid pressure output means AR to the left and right rear wheel disc brakes BRL and BRR when the solenoids 41 and 42 are demagnetized. When the solenoid 41 is energized while the solenoid 42 is demagnetized, the output fluid pressure of the output port 24R can be transmitted to the left rear wheel disc brake BRL, but it is not possible to transmit the output fluid pressure to the right rear wheel disc brake BRR. The position where the transmission is cut off (the upper position in FIG. 1) and the output port 2 when the solenoid 42 is energized while the solenoid 41 is demagnetized.
The output fluid pressure of 4R is applied to the right rear wheel disc brake BRR.
It is possible to transmit the disc brake to the left rear wheel BRL.
This is a 3-port, 3-position electromagnetic switching control valve that can be switched between a position where transmission is cut off (lower position in Fig. 1) and a position where transmission is cut off.

In FIG. 4, the solenoid 3 of the fail-safe electromagnetic switching valve 27L in the left fluid pressure system LL
6L, solenoid 36R of the fail-safe electromagnetic switching valve 27R in the right fluid pressure system LR, solenoids 41 and 42 of the cutoff valve 40 in the collective fluid pressure system LT.
, the motors 9FL, 9FR, 9R of the electric fluid pressure output means AFL, AFR, AR, and the first, second and third alarms 44, 45, 46 are controlled by the electronic control unit 4.
7, and the electronic control unit 47 includes a main processing section 48 and three sub processing sections 49.
It is equipped with FL, 49FR, and 49R.

The main arithmetic processing section 48 includes the vehicle speed detection circuit 5
1, an anti-lock control circuit 52, a road surface friction coefficient determination circuit 53, an autobrake control circuit 54, a high select circuit 55, a failure diagnosis circuit 56, a brake distribution control circuit 57, and three correction circuits 58FL, 58FR, 5
8R.

The vehicle speed detection circuit 51 detects the left front wheel WFL,
Wheel speed detectors 43FL, 43FR, and 4 are installed on the right front wheel WFR, left rear wheel WRL, and right rear wheel WRR, respectively.
The vehicle body speed VV is detected based on the detected values of 3RL and 43RR.

The anti-lock control circuit 52 controls the left front wheel WFL, the left front wheel WFL, and It detects whether the front right wheel WFR and both rear wheels WRL, WRR are about to lock up, and adjusts the braking pressure of the front left wheel disc brake BFL, the front right disc brake BFR, and the disc brakes BRL, BRR for both rear wheels. Each is configured to output a control signal.

The road surface friction coefficient determination circuit 53 determines that the friction coefficient μ of the road surface on which the vehicle is running is determined to be a predetermined road surface friction coefficient μ.
0 For example, it is configured to output a high-level signal when it is determined that the speed is 0.4 or less, and the detection values of the wheel speed detectors 43FL, 43FR, 43RL, and 43RR as well as the vehicle body speed detection circuit 51 are configured to output a high-level signal. The obtained vehicle speed VV is input to the road surface friction coefficient determination circuit 53. Therefore, the road surface friction coefficient determination circuit 53 determines the vehicle speed V
The reference wheel speed obtained by adding a predetermined slip rate to V and the wheel speed detectors 43FL, 43FR, 43RL,
43RR is compared with the detected value of each wheel speed detector 43.
When at least one of the detected values of FL, 43FR, 43RL, and 43RR becomes equal to or less than the reference wheel speed, it is determined that the friction coefficient μ has become equal to or less than a predetermined road surface friction coefficient μ0, and the road surface friction coefficient determination circuit 53 outputs a high level signal.

The autobrake control circuit 54 uses a laser radar or the like to detect the distance between the vehicle speed VV obtained by the vehicle speed detection circuit 51 and a target obstacle such as another vehicle traveling in front. Based on the distance L obtained by the distance detector 50 of each disc brake BFL,
Determine whether or not BFR, BRL, and BRR should be activated automatically, and depending on the determination result: ■ A signal to notify the driver in advance of the start of automatic braking operation; ■
Notifies the vehicle behind of the start of automatic brake operation, and also activates each disc brake BFL, BFR, BRL, B.
A signal for pumping the RR, and ■
A signal for fully operating each disc brake BFL, BFR, BRL, BRR is output in stages, and each disc brake BFL, BFR, BRL, BR
When a high-level signal is input from the road surface friction coefficient determination circuit 53 during pumping operation of R, the output signal is switched so as to fully operate each disc brake BFL, BFR, BRL, and BRR.

This autobrake control circuit 54 is shown in FIG.
It is configured as shown in FIG. ，
68, 69, 70 and AND gates 71, 72, 73,
74, a pumping signal output device 75, and first, second, third, fourth and fifth level setters 76, 77, 78, 7
9,80.

First, second and third reference distance calculators 61
, 62 and 63 are basically based on the following equation (1) based on the vehicle speed VV obtained by the vehicle speed detection circuit 51 and the distance L obtained by the distance detector 50. L
Calculate R respectively.

LR=VV・(TD+TX)+(VV2
-VB 2 )/(2α)...(1) Here, TD
is set as the time until each actuator, that is, the electric fluid pressure output means AFL, AFR, AR and the first and second alarms 44, 45 start operating according to the signal output from the autobrake control circuit 54. TX is set as the time required from signal input to signal output within the autobrake control circuit 54, α is the set deceleration of the vehicle, and VB
is the traveling speed of an obstacle, such as a vehicle in front, whose distance L is detected by the distance detector 50, and is a value calculated by the following equation (2).

VB =VV +dL/dt...(2) Then, {(
VV 2 −VB 2 )/(2α)} indicates the difference in braking distance between the vehicle and the vehicle in front, which is a reference obstacle. Further, (VV TD) is an electric fluid pressure output means A according to a signal output from the autobrake control circuit 54.
FL, AFR, AR and 1st and 2nd alarm 4
4, 45 is the distance the vehicle travels before it starts operating, and (VV TX) is the auto brake control circuit 5.
This is the distance the vehicle travels while determining whether or not to take action to avoid a collision.

By the way, the set deceleration α is set differently in each of the reference distance calculators 61 to 63, and the first reference distance calculator 61 uses the set deceleration α1 as the set deceleration α1.
A first reference distance LR1 corresponding to the set deceleration α2 is obtained, and the second reference distance calculator 62 obtains a second reference distance L corresponding to the set deceleration α2.
R2 is obtained, and the third reference distance calculator 63 obtains a third reference distance LR3 corresponding to the set deceleration α3. Moreover, each set deceleration α1, α2, α3 is α1 > α2
>α3, and LR1
<LR2<LR3.

The non-inverting input terminal of the first comparator 64 has a first
The first reference distance LR1 calculated by the reference distance calculator 61 is input, and the distance L obtained by the distance detector 50 is input to the inverting input terminal. Further, the second reference distance LR2 calculated by the second reference distance calculator 62 is input to the non-inverting input terminal of the second comparator 65, and the distance detector 5 is input to the inverting input terminal.
The distance L obtained at 0 is input. Furthermore, the third comparator 6
The third reference distance LR3 calculated by the third reference distance calculator 63 is input to the non-inverting input terminal 6, and the distance L obtained by the distance detector 50 is input to the inverting input terminal. Therefore, in the process in which the distance L obtained by the distance detector 50 becomes smaller, the output of the third comparator 66 becomes high level, then the output of the second comparator 65 becomes high level, and finally the output of the first comparator 66 becomes high level. The output of the device 64 becomes high level.

The output signal of the first comparator 64 and the output signal of the AND gate 71 are input to the OR gate 67 in parallel. Therefore, the OR gate 67 goes high at least one of when the distance L becomes less than the first reference distance LR1 calculated by the first reference distance calculator 61 and when the output of the AND gate 71 becomes a high level. It will output a level signal. Moreover, the output signal of the second comparator 65 and the output signal of the road surface friction coefficient determination circuit 53 are inputted in parallel to the AND gate 71,
The D gate 71 is set to a high level when the distance L becomes less than the second reference distance LR2 calculated by the second reference distance calculator 62 and the friction coefficient μ of the running road surface becomes equal to or less than a predetermined road surface friction coefficient μ0. It outputs a signal.

The pumping signal output device 75 operates intermittently in response to the output signal of the second comparator 65 being at a high level, that is, when the distance L becomes less than the second reference distance LR2 calculated by the second reference distance calculator 62. The output signal of the pumping signal output device 75 and the output signal of the OR gate 67 are input to the OR gate 68. Therefore, the OR gate 68 determines whether the distance L is less than the first reference distance LR1 or the distance L is less than the second reference distance LR1.
2 and the friction coefficient μ of the road surface is less than or equal to a predetermined road surface friction coefficient μ0, a continuous high-level full braking command signal is output. When this is not true and the distance L is less than the second reference distance LR2, an intermittent high-level pumping braking command signal is output. An output terminal 81 connected to this OR gate 68 is input to a high select circuit 55 shown in FIG.

The output signals of the first and second level setters 76 and 77 are connected in parallel to the OR gate 69, and the first level setter 76 detects when the signal of the OR gate 67 becomes high level. At times, an alarm command signal of a preset level is output. Further, the second level setter 77 is an AND
In response to a high level signal being input from the gate 72, an alarm command signal of a lower level than the first level setter 76 is output.
The output signal of the gate 67 is inverted and inputted, and the output signal of the second comparator 65 is also inputted. Therefore, AN
The D gate 72 outputs a high level signal when the pumping braking command signal is output from the output terminal 81, and the second level setter 77 outputs an alarm signal in response.

Output terminal 82 to which OR gate 69 is connected
is connected to the first alarm device 44. Then the first alarm 4
Reference numeral 4 designates an alarm device such as a lamp that activates an alarm for the vehicle behind; when a pumping braking command signal is output from the output terminal 81, the first alarm device 44 executes a low-level alarm operation; When a full braking command signal is output from 81, a high level alarm is activated.

The output signals of the third, fourth, and fifth level setters 78, 79, and 80 are inputted in parallel to the OR gate 70. The third level setter 78 includes an OR gate 67
When the signal becomes high level, an alarm command signal of a preset level is output. Also, the fourth level setter 79
outputs an alarm command signal at a lower level than the third level setter 78 in response to a high level signal input from the AND gate 73;
The output signal of the OR gate 67 is inverted and inputted, and the output signal of the second comparator 65 is also inputted to the input circuit. Therefore, the AND gate 73 outputs a high level signal when the pumping braking command signal is output from the output terminal 81. Further, the fifth level setter 80 outputs an alarm command signal at a lower level than the fourth level setter 79 in response to a high level signal input from the AND gate 74. The output signal of the OR gate 67 and the output signal of the second comparator 65 are inverted and input, and the output signal of the third comparator 66 is also input. Therefore, the AND gate 74 outputs a signal from the output terminal 81 when the output signal at the output terminal 81 is at a low level, and when the output signal from the output terminal 81
2 is at a low level, and the output signal of the third comparator 6 is low level.
When the output signal of No. 6 is at a high level, a high level signal is output.

Output terminal 83 to which OR gate 70 is connected
is connected to the second alarm 45. This second alarm device 45 is an alarm device such as a buzzer that activates an alarm to the driver. Therefore, the distance L is the first and second reference distances LR1,L
When the distance L is equal to or greater than R2 and less than the third reference distance LR3, the second alarm device 45 executes a low-level alarm operation, and when the distance L is equal to or greater than the first reference distance LR1 and less than the third reference distance LR
When the pumping braking command signal is output from the output terminal 81 in a state where the distance L is less than 2, the second alarm 45 executes an intermediate level alarm operation, and when the distance L is less than the first reference distance LR1 or the distance L is the second When the full braking command signal is output from the output terminal 81 in a state where the road surface friction coefficient μ is less than the reference distance LR2 but less than the set road surface friction coefficient μ0, the second alarm 45 activates a high-level alarm. will be executed.

Referring again to FIG. 4, the high select circuit 55
A stroke sensor SS and a pressure sensor SM attached to the master cylinder M are connected in parallel to an output terminal 81 of the autobrake control circuit 54 (see FIG. 5). The high select circuit 55 selects the highest level output from the stroke sensor SS, pressure sensor SM and auto brake control circuit 54 and inputs it to the brake distribution control circuit 57. Therefore, the high select circuit 55 inputs the braking command signal from the autobrake control circuit 54 to the brake distribution control circuit 57 when the driver of the vehicle is not performing a braking operation.
When the driver of the vehicle performs a braking operation, a signal from the stroke sensor SS or pressure sensor SM is input to the brake distribution control circuit 57. Therefore, even if a fluid pressure failure occurs in the fluid pressure system connected to the master cylinder M when the vehicle driver performs a braking operation, the stroke sensor SS reliably detects the braking operation and the high select circuit 55 sends the brake distribution control circuit. 57, a signal corresponding to the amount of braking operation can be reliably inputted.

The failure diagnosis circuit 56 includes a left fluid pressure system LL.
The detection value of the left front wheel pressure sensor SFL detects the fluid pressure of the right front wheel, the detection value of the right front wheel pressure sensor SFR detects the fluid pressure of the right fluid pressure system LR, and the detection value of the right front wheel pressure sensor SFR detects the fluid pressure of the collective fluid pressure system LT. The detected value of the pressure sensor SR for the master cylinder M, each detected value of the stroke sensor SS and the pressure sensor SM attached to the master cylinder M, and the fail signals from each sub-processing section 49FL, 49FR, 49R are inputted. When it is determined that a braking operation has been performed based on the signals from stroke sensor SS and pressure sensor SM, each pressure sensor SFL, SFR, SR
The failure is determined by determining whether brake pressure is obtained based on the detected value of each sub-processing unit 49FL,
A failure is determined based on whether a fail signal is input from 49FR, 49R, and when a failure is determined, the third
The alarm 46 is activated. Moreover, the left fluid pressure system LL
When it is determined that the electric fluid pressure output means AFL for the left front wheel is malfunctioning, the failure diagnosis circuit 56 activates the solenoid 36L of the fail-safe electromagnetic switching valve 27L.
is demagnetized, and when it is determined that the front right wheel electric fluid pressure output means AFR in the right fluid pressure system LR is at fault, the solenoid 36R of the fail-safe electromagnetic switching valve 27R is demagnetized by the failure diagnosis circuit 56. As a result, in the left fluid pressure system LL, the first
Output port 2 and left front wheel disc brake BFL are communicated, and master cylinder M is connected to right fluid pressure system LR.
2nd output port 3 and right front wheel disc brake B
The FRs will be communicated with each other. Therefore, even if the electric fluid pressure output means AFL, AFR for both front wheels fail, fluid pressure can be ensured by the master cylinder M that outputs fluid pressure in response to the driver's operation.

Further, the failure diagnosis circuit 56 activates both solenoids 41 of the cutoff valve 40 in response to the integral value of the difference between the detected values of the left front wheel pressure sensor SFL and the right front wheel pressure sensor SFR exceeding a predetermined value. , 42, and when the detected value of the left front wheel pressure sensor SFL is large, the solenoid 42 is energized while the solenoid 41 is kept in the demagnetized state, and the When the detected value of the pressure sensor SFR is large, the solenoid 4 remains in the demagnetized state.
1 is excited. As a result, when the fluid pressure in the left fluid pressure system LL becomes greater than the fluid pressure in the right fluid pressure system LR, the shutoff valve 40 controls the rear wheel electric power transmission to the right rear wheel disc brake BRR in the collective fluid pressure system LT. While maintaining the fluid pressure transmission from the rear wheel electric fluid pressure output means AR, the fluid pressure transmission from the rear wheel electric fluid pressure output means AR to the left rear wheel disc brake BRL is interrupted, and the right fluid pressure system LR is
When the fluid pressure in the left fluid pressure system LL becomes greater than the fluid pressure in the left fluid pressure system LL, fluid pressure transmission from the rear wheel electric fluid pressure output means AR to the left rear wheel disc brake BRL in the collective fluid pressure system LT is maintained. Rear wheel electric fluid pressure output means AR to the right rear wheel disc brake BRR
This will cut off fluid pressure transmission from the

A signal from the high select circuit 55 is input to the brake distribution control circuit 57, and a signal from the failure diagnosis circuit 56 is input to both fail-safe electromagnetic switching valves 27L.
, 27R are inputted to the solenoids 36L, 36R. Therefore, the brake distribution control circuit 57
A signal for executing a braking operation at a level corresponding to the amount of braking operation by the driver, or a braking output from the autobrake control circuit 54 to execute automatic braking to avoid a collision with the vehicle in front during non-braking operation. In response to input of a command signal, electric fluid pressure output means AFL for left and right front wheels is activated.
, The disc brake for the left front wheel BFL and the disc brake B for the right front wheel are switched depending on whether the AFR is normal or malfunctions.
FR, and disc brakes for both rear wheels BRL, BR
It outputs a signal corresponding to the braking pressure distributed in advance to be applied to R.

The output from the brake distribution control circuit 57 is given to each correction circuit 58FL, 58FR, 58R. In addition, anti-lock control signals from the anti-lock control circuit 52 are also input to each of the correction circuits 58FL, 58FR, and 58R. A signal corresponding to the braking pressure corrected by is sent to each correction circuit 58F.
They are output from L, 58FR, and 58R, respectively.

[0046] Sub-arithmetic processing units 49FL, 49FR, 49R
are self-diagnosis circuits 84FL, 84FR, 84R,
drive control circuits 85FL, 85FR, and 85R, respectively, and self-diagnosis circuits 84FL and 84FR.
, 84R have corresponding pressure sensors SFL, SFR, S
R and corresponding correction circuits 58FL, 58FR, 58
A signal is input from each drive control circuit 85F.
Corresponding pressure sensor SFL for L, 85FR, 85R
, SFR, SR and corresponding correction circuits 58FL, 5
Signals are input from 8FR and 58R, respectively.

[0047] The self-diagnosis circuits 84FL, 84FR,
84R, even though the signal indicating the braking pressure is input from the correction circuits 58FL, 58FR, and 58R.
When the signal from the corresponding pressure sensor SFL, SFR, SR does not reach a predetermined value, it is determined that each electric fluid pressure output means AFL, AFR, AR is in failure and a fail signal is input to the failure diagnosis circuit 56. It is something to do.

Furthermore, drive control circuits 85FL, 85FR, 8
5R is the corresponding pressure sensor SFL, SFR, SR
The motors 9FL and 9FL of each electric fluid pressure output means AFL, AFR, and AR are arranged so that the detected value of the motor 9FL, AFR, and AR corresponds to the signal inputted from the correction circuits 58FL, 58FR, and 58R.
It outputs a signal for PID control of 9FR and 9R.

Next, to explain the operation of the first embodiment, the distance L between the traveling vehicle and an obstacle such as a vehicle in front of the traveling vehicle is
is detected by the distance detector 50 and input to the autobrake control circuit 54 of the main processing section 48 in the electronic control unit 47. Then, the autobrake control circuit 54 determines the first, second, and third brake speeds based on the distance L and the vehicle speed VV obtained by the vehicle speed detection circuit 51.
Reference distances LR1, LR2, LR3 have been calculated, and based on the comparison results between these reference distances LR1, LR2, LR3 and the distance L, signals are sent to the first and second alarm devices 44, 45 and the high select circuit 55. Output. That is, it is calculated so that the first reference distance LR1<second reference distance LR2<third reference distance LR3, and when the distance L becomes less than the third reference distance LR3, braking is applied to avoid a collision with the vehicle in front. In order to prompt the driver to perform the operation and notify the driver in advance that automatic braking will be executed, a low alarm is installed on the second alarm 45 so that the driver does not feel uncomfortable when automatic braking is executed. A signal for executing a level warning operation is output from the autobrake control circuit 54. In addition, when the distance L becomes less than the second reference distance LR2, a signal for causing the second alarm 45 to execute an intermediate level alarm operation and a signal to notify the vehicle behind of the start of automatic brake operation are sent to the rear vehicle. A signal for causing the first alarm device 44 to execute a low-level alarm operation in order to avoid a collision with a vehicle is output from the autobrake control circuit 54, and each disc brake BFL, BFR, B
A signal for pumping RL and BRR is applied from the autobrake control circuit 54 to the high select circuit 55. Furthermore, when the distance L becomes less than the third reference distance LR3, a signal for causing the first and second alarm devices 44 and 45 to execute a high-level alarm operation is output from the autobrake control circuit 54, and each disc A signal for fully operating the brakes BFL, BFR, BRL, and BRR is applied from the autobrake control circuit 54 to the high select circuit 55.

In this way, when automatic braking is performed to avoid a collision with the vehicle in front, a warning to the driving vehicle and a warning to the vehicle behind are sequentially sent depending on the distance between the vehicle and the vehicle in front. This system notifies the driver of the danger before the automatic braking is executed, prompting the driver to perform the braking operation, and prevents the driver from feeling uncomfortable when the automatic braking is executed. By prompting the driver to decelerate, it is possible to prevent a collision with the vehicle behind during automatic braking. Further, when automatic braking is executed, full braking is not performed from the beginning, but pumping braking, that is, gentle braking is first performed, and then full braking is performed, so that the driver feels less discomfort.

By the way, each of the above reference distances LR1 and LR2
, LR3, the calculation formula shown in equation (1) is as follows:
According to the signal output from the autobrake control circuit 54,
The time TD until the electric fluid pressure output means AFL, AFR, AR and the first and second alarms 44, 45 start operating, and the time TX required from signal input to signal output within the autobrake control circuit 54. It includes a delay term {VV ・(TD +TX)} that takes into consideration
By including a delay time caused by the control circuit itself in R1, LR2, and LR3, more precise automatic braking control for collision prevention becomes possible.

Furthermore, when executing pumping braking, if the friction coefficient μ of the road surface becomes less than the set value μ0, there is a possibility that the set deceleration when calculating the reference distance cannot be achieved, so pumping braking is changed to full braking. This makes it possible to perform braking according to the conditions of the road surface. Note that when at least one of the wheels WFL, WFR, WRL, and WRR is about to lock when switching from pumping braking to full braking, the wheel that is about to lock among the electric fluid pressure output means AFL, AFR, and AR. The output fluid pressure corresponding to the wheel is controlled in accordance with the output signal of the anti-lock control circuit 52, so that wheel lock does not occur.

In addition to the automatic braking control for collision avoidance described above, when the driver depresses the brake pedal 26 to perform a braking operation, each electric fluid pressure output means AFL is activated in accordance with the braking pressure set by the brake distribution control circuit 57. ,AFR
, AR are controlled, and braking force is obtained from each of the disc brakes BFL, BFR, BRL, and BRR accordingly.

[0054] Moreover, regardless of whether automatic braking is applied to avoid a collision or when braking is performed by the driver, the left fluid pressure system L
When the fluid pressure in the right fluid pressure system LR is different from the fluid pressure in the right fluid pressure system LR, the failure diagnosis circuit 56 activates the solenoid 41,
By controlling the excitation/demagnetization of 42, fluid pressure transmission/cutoff from the rear wheel electric fluid pressure output means AR to the left and right brakes BRL and BRR of the collective fluid pressure system LT is switched. That is, when the fluid pressure in the left fluid pressure system LL is higher than the fluid pressure in the right fluid pressure system LR, the solenoid 41 is demagnetized and the solenoid 42 is energized by the failure diagnosis circuit 56, so that the cutoff valve 40 is energized.
The fluid is transmitted from the rear wheel electric fluid pressure output means AR to the left rear wheel disc brake BRL while maintaining fluid pressure transmission from the rear wheel electric fluid pressure output means AR to the right rear wheel disc brake BRR. Blocks pressure transmission. Further, when the fluid pressure in the right fluid pressure system LR is higher than the fluid pressure in the left fluid pressure system LL, the fault diagnosis circuit 56 demagnetizes the solenoid 42 and energizes the solenoid 41. While maintaining fluid pressure transmission from the rear wheel electric fluid pressure output means AR to the rear wheel disc brake BRL, the right rear wheel disc brake BRR is
This will cut off fluid pressure transmission from the rear wheel electric fluid pressure output means AR to the rear wheels. In this way, even if a difference in fluid pressure occurs between the left and right fluid pressure systems LL and LR, the left and right fluid pressure systems LL and LR of the left and right brakes BRL and BRR of the collective fluid pressure system LT. By cutting off the transmission of fluid pressure to the brake on the same side as the high pressure side of the
It is possible to eliminate the imbalance between the left and right braking forces of the vehicle as a whole, and to prevent yaw motion from occurring in the vehicle without the driver's steering operation.

Furthermore, the failure diagnosis circuit 56 outputs a signal for switching between demagnetization and excitation of both solenoids 41 and 42 based on the integral value of the difference between the detected values of the left front wheel pressure sensor SFL and the right front wheel pressure sensor SFR. Since the control is performed in consideration of the passage of time, no drive signal is generated even if the braking force differs between the left fluid pressure system LL and the right fluid pressure system LR during anti-lock brake control or traction control. First, it is possible to prevent control hunting from occurring due to frequent switching between excitation and demagnetization of the solenoids 41 and 42.

FIG. 6 shows a modification of the main part of the failure diagnosis circuit. In the failure diagnosis circuit 56', the part that switches and controls the excitation and demagnetization of both solenoids 41 and 42 is connected to the left front wheel pressure sensor SFL. and right front wheel pressure sensor SFR
Arithmetic circuit 87 that calculates the difference between the detected pressures PL and PR
Comparators 88L, 88R output signals in response to the difference between L, 87R and the detected pressures PL, PR exceeding the reference values input from the reference terminals 89L, 89R.
and the solenoid 4 in response to the signal outputs from the comparators 88L and 88R continuing beyond the set time.
Timer 90L that outputs a signal to excite 1 and 42
, 90R.

Even in this case, by taking into consideration the passage of time, it is possible to prevent control hunting from occurring due to frequent switching between excitation and demagnetization of the solenoids 41 and 42.

The autobrake control circuit 54 in the above embodiment may be replaced by a computer that executes a control procedure according to a preset program, and FIG. 7 is a flowchart showing the control procedure.

In FIG. 7, the vehicle speed VV is read in the first step S1, the distance L obtained by the distance detector 50 is read in the second step S2, and the distance L obtained by the distance detector 50 is read in the third step S3.
Then, the traveling speed VB of the vehicle ahead is calculated. Furthermore, in the fourth step S4, the first, second and third reference distances LR1, LR2, and LR3 are calculated, respectively.

In the fifth step S5, it is determined whether the distance L exceeds the first reference distance LR1 (L>LR1), and if L≦LR1, full braking is executed from the sixth step S6. signal is output. Also L>
If it is LR1, the process proceeds to a seventh step S7, and in this seventh step S7 it is determined whether the distance L exceeds the second reference distance LR2 (L>LR2). Therefore, L≦
When it is LR2, the process goes to the eighth step S8, and again L>
If it is LR2, the process advances to the tenth step S10.

In the eighth step S8, the first alarm 44 is activated and the pumping signal output device 7 is activated.
5 outputs an intermittent high level signal for executing pumping braking. In the ninth step S9, it is determined whether the friction coefficient μ of the road surface exceeds a predetermined road surface friction coefficient μ0, for example, 0.4, and when it is determined that μ≦μ0, the process proceeds to the sixth step S6. A signal for full braking is output.

[0062] In the tenth step S10, the distance L is the third
It is determined whether the reference distance LR3 is exceeded (L>LR3), and if L≦LR1, the eleventh step S
At step 11, a signal for activating the second alarm device 45 is output.

In this way, the distance L is compared with the first reference distance LR1 having the smallest value, the distance L is compared with the second reference distance LR2 whose value is larger than the first reference distance LR1,
By comparing the distance L with the third reference distance LR3, which has the largest value, in this order, the possibility of collision with the vehicle in front is judged from the side with the highest possibility, thereby eliminating unnecessary calculations. Processing can be omitted and efficiency of arithmetic processing can be improved.

[0064]

As described above, according to the first feature of the present invention, by including the delay time caused by the control circuit itself in the reference distance, which is a reference value for collision avoidance, more precise collision detection can be achieved. Automatic braking control for collision prevention becomes possible.

According to the second feature of the present invention, the control circuit controls the control circuit when a plurality of reference distances calculated based on a plurality of predetermined decelerations and the distances each have a predetermined relationship. Furthermore, since the actuator is configured to output signals for causing the actuator to perform mutually different operations, the actuator can perform various operations depending on the level of possibility of collision.

[Brief explanation of drawings]

FIG. 1 is a diagram of a braking fluid pressure system of a vehicle according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view of the electric fluid pressure output means.

FIG. 3 is a longitudinal cross-sectional view of the fail-safe electromagnetic switching valve.

FIG. 4 is a block diagram showing a schematic configuration of an electronic control unit.

FIG. 5 is a block diagram showing a schematic configuration of an autobrake control circuit.

FIG. 6 is a block diagram showing a modification of the main part of the failure determination circuit.

FIG. 7 is a flowchart showing a control procedure when the autobrake control circuit is a computer.

[Explanation of symbols]

44...First alarm device 45 as an actuator...
- Second alarm 50 as an actuator...Distance detector 51...Vehicle speed detector 54...Auto brake control circuit AFL...Electric fluid pressure output means for left front wheel AFR as an actuator...・Electric fluid pressure output means AR for the right front wheel as an actuator ...Electric fluid pressure output means for the rear wheel as an actuator

Claims (2)

[Claims] 1. A vehicle speed detector (51) for detecting the vehicle body speed (VV) of a vehicle, a distance detector (50) for detecting a distance (L) of the vehicle to a reference obstacle, and a distance detector (50) for detecting a distance (L) of the vehicle to a reference obstacle. Actuators (AFL, AFR, AR, 44, 45) that perform operations necessary to avoid collision with objects, and a reference distance (LR) to the reference obstacle based on the vehicle speed (VV) and distance (L). and outputs a signal for operating the actuators (AFL, AFR, AR, 44, 45) when the reference distance (LR) and the distance (L) meet a predetermined relationship. In the vehicle collision prevention device, the control circuit (54) has the following formula: LR = VV ・(TD +TX ) + (VV 2
−VB 2 )/(2α) However, TD; Control circuit (
54) according to the signal output from the actuator (AFL).
, AFR, AR, 44, 45) starts operation TX; Time required from signal input to signal output within the control circuit (54) α; Set deceleration of the vehicle VB; Traveling speed of the reference obstacle A collision prevention device for a vehicle, characterized in that a reference distance (LR) is calculated according to the following calculation formula: VB = VV + dL/dt. 2. The control circuit (54) is configured to mutually control the distance (L) when a plurality of reference distances calculated based on a plurality of predetermined decelerations and the distance (L) each have a predetermined relationship. Actuators (AFL, AF)
2. The collision prevention device for a vehicle according to claim 1, wherein the vehicle collision prevention device is configured to output a signal for causing the collision prevention device to perform the collision prevention device R, AR, 44, 45).