JP3201092B2 - Automatic brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic brake device, and more particularly to an automatic brake device mounted on a vehicle to avoid collision with a forward obstacle.

[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.

When the automatic brake is operated, the driver usually does not perceive that the vehicle has unduly approached an obstacle ahead. Therefore, if sudden braking by the automatic braking is performed suddenly, it is an unexpected impact for the driver, which may give an excessive shock.

Japanese Patent Application Laid-Open No. 54-40432 pays attention to this point, and when an automatic brake is activated, a driver is perceived that the automatic brake is activated prior to the actual braking for the purpose of decelerating the vehicle. For this reason, a brake device for performing preliminary braking is disclosed. In this case, the driver can predict that sudden braking will be performed by preliminary braking,
In addition to being able to prepare for the sudden braking, it is also possible to perceive abnormal approach to an obstacle ahead and take some action by itself.

[0005]

By the way, when a temporary deceleration occurs in a vehicle, assuming that the deceleration is the same, it is empirical that the lower the vehicle speed, the more the deceleration is perceived as a large impact. Is known to. Therefore, the driver of the vehicle perceives even a relatively small deceleration during low-speed running, but the phenomenon may not be perceived unless the deceleration is relatively large during high-speed running.

[0006] On the other hand, the above-mentioned conventional automatic braking device performs preliminary braking to perceive its operation prior to the actual braking by the automatic braking, but the braking force at the time of the preliminary braking (hereinafter referred to as the preliminary braking force). The parentheses are the same both when traveling at high speed and when traveling at low speed. For this reason, there has been a problem that although a perceptual effect is appropriately exhibited to the driver in a situation where the vehicle speed is relatively low, an appropriate perceptual effect is not exhibited during high-speed traveling.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in performing the preliminary braking prior to the actual braking by the automatic brake, the above problem is solved by changing the preliminary braking force as the vehicle speed becomes higher. It is an object to provide a solvable automatic braking device.

[0008]

FIG. 1 is a block diagram showing the principle of an automatic brake device which achieves the above object. That is, the above object is to determine the possibility of a collision based on the measurement result of the distance measuring means 1 for measuring the distance to the obstacle ahead of the vehicle as shown in FIG. Is a mechanism for activating an automatic brake by supplying a predetermined brake oil pressure to the wheel brake mechanism 2 irrespective of the driver's intention. Prior to performing the actual braking for the purpose of decelerating the vehicle, in an automatic brake system comprising an automatic braking mechanism 3 for preliminary braking for the purpose of automatic brake notify the driver that operates, the preliminary
Preliminary braking force that varies the preliminary braking force during braking based on vehicle speed
Changing means 4 and changing the preliminary braking force changing means 4
The higher the vehicle speed at the start of preliminary braking, the more
This is achieved by an automatic braking device characterized in that the braking force is changed greatly .

In the automatic brake device having the above-mentioned structure, a vehicle weight detecting means 5 for detecting a vehicle weight is provided, and the preliminary braking force changing means 4 corrects the braking force at the time of the preliminary braking according to the vehicle weight. Such an automatic braking device is effective for ensuring a more certain perceptual effect.

[0010]

In the automatic brake device according to the present invention, the automatic brake mechanism 3 determines that the distance from the obstacle ahead measured by the distance measuring means 1 is shorter than a predetermined determination distance and that there is a possibility of collision. Then, the operation of the automatic brake is started to avoid a collision. Then, before the sudden braking by the automatic braking is performed, the preliminary braking is performed so that the driver can perceive the situation.

In this case, the preliminary braking force is changed by the preliminary braking force changing means 4 as the vehicle speed at the start of the preliminary braking is higher. For this reason, the impact received by the driver due to the temporary deceleration due to the preliminary braking becomes the same level regardless of the vehicle speed, and a good perceptual effect is always exerted.

When the preliminary braking force changing means 4 corrects the preliminary braking force in consideration of the detection result of the vehicle weight detecting means 5, the influence of the vehicle weight is excluded from the deceleration generated during the preliminary braking. Therefore, a deceleration that can always exert an appropriate perceptual effect is secured.

[0013]

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

In FIG. 1, reference numeral 10 denotes a hydraulic booster (hereinafter, referred to as a hydraulic booster).
12 is a tandem type brake master cylinder (hereinafter simply referred to as a master cylinder).
It is. The master cylinder 12 includes a first pressurizing piston and a second pressurizing piston that are displaced in conjunction with the brake pedal 14 therein, and generate hydraulic pressure when the brake pedal 14 is depressed.

Here, the hydraulic pressure generated due to the displacement of the first pressurizing piston and the second pressurizing piston is supplied to the proportioning bypass valve 2 by the liquid passages 16 and 18, respectively.
It is led to 0. The hydraulic pressure generated by the first pressurizing piston is applied to the wheel cylinders 22 and 24 of the brakes of the left and right rear wheels RL and RR, and the hydraulic pressure generated by the second pressurizing piston is applied to the left and right front wheels FL and FR. Each brake is connected to a wheel cylinder 26, 28.

That is, the automatic brake device according to the present embodiment is of a two-way system of front and rear.
26 and 28 correspond to the brake mechanism 2 described above.
In the present vehicle, the left and right rear wheels RL, RR are drive wheels.

The proportioning bypass valve 20
When the hydraulic pressure is normally generated in both the front wheel system and the rear wheel system, the wheel cylinders 2 of the rear wheels RL and RR
The fluid pressure supplied to the wheel cylinders 2, 24 is reduced at a fixed ratio to the fluid pressure supplied to the wheel cylinders 26, 28 of the front wheels FL, FR. On the other hand, when the hydraulic pressure is not normally generated in the front wheel system, the hydraulic pressure raised by the first pressurizing piston is supplied to the wheel cylinders 22, 24 of the rear wheels RL, RR without reducing the pressure. .

A pressure increasing device 30 is connected between the proportioning bypass valve 20 and the wheel cylinders 26, 28 of the front wheels FL, FR as shown in FIG. The pressure increasing device 30 is a device for further increasing the hydraulic pressure raised by the second pressure piston of the master cylinder 12, and its role will be described later.

The first and second pressurizing chambers in which the first and second pressurizing pistons of the master cylinder 12 generate hydraulic pressure are respectively a first pressurizing piston and a second pressurizing piston. When the pressurizing piston is not depressed, both are in communication with the reserve tank 32. For this reason, when the brake fluid becomes insufficient, the brake fluid is appropriately replenished from the reserve tank 32 to the master cylinder 12 during non-braking.

The booster 10 is provided integrally with the master cylinder 12 to boost the depression force of the brake pedal 14 and transmit the boosted pressure to the first pressure piston and the second pressure piston. That is, a power pressure chamber is formed inside the booster 10 so as to be switched from a state communicating with the reservoir tank 32 to a state communicating with the accumulator 34 when the brake pedal 14 is depressed.

The power pressure chamber is provided with a power piston for transmitting the pressure in the power pressure chamber to the first pressure piston and the second pressure piston of the master cylinder 12. Therefore, when the brake pedal 14 is depressed,
The high-pressure hydraulic pressure supplied via the accumulator 34 is applied to the power piston that has been opened to the internal pressure of the reservoir tank 32.

Then, the first pressure piston and the second pressure piston of the master cylinder 12 are advanced, and the hydraulic pressure is transmitted to the wheel cylinders 22, 24, 26, 28. The power chamber is configured so that when the pedaling force and the reaction force of the brake pedal 14 are balanced, the power chamber does not communicate with the accumulator 34 or the reservoir tank 32. Therefore, when the amount of depression of the brake pedal 14 is stabilized, the boosting force is thereafter maintained at a constant value.

The accumulator 34 is supplied with a hydraulic pressure that has been increased by a pump 38 driven by a motor 36 via a check valve 40. At this time, the accumulator 34
Is controlled within a certain range by controlling the start and stop of the motor 36 based on the output signal of the pressure sensor 42.

An abnormal decrease in the hydraulic pressure of the accumulator 34 is detected by the pressure switch 44, and the brake warning lamp is turned on and the buzzer is operated. The hydraulic pressure of the accumulator 34 is guarded by a relief valve 46 at an appropriate level.

Here, the automatic brake device of this embodiment is
If an excessive braking force occurs, the wheel cylinders 22 and 2
Anti-lock control for releasing the brake oil pressure supplied to the wheels 4, 26, 28 to unlock the wheels, and, when excessive driving force occurs, generating braking force on the driving wheels to reduce the idling of the wheels. The configuration is based on the premise that acceleration slip control for achieving convergence is performed.

Therefore, as shown in FIG. 2, between the proportioning bypass valve 20 and the wheel cylinders 34, 26 of the rear wheels RL, RR, there is provided an electromagnetic directional control valve 50 and a directional control valve 3 at three positions. The direction switching valves 54 and 56
The pressure booster 30 and the wheel cylinders 2 of the front wheels FL and FR
6, 28, two electromagnetic directional control valves 58, 60 are provided.

The electromagnetic directional control valve 50 on the rear wheels RL, RR is connected to the power pressure chamber of the booster 10 or the accumulator 34 via another electromagnetic directional control valve 52, and the electromagnetic directional control valve on the front wheels FL, FR is used. The switching valves 58 and 60 are connected to three-way switching valves 66 and 68 via liquid passages 62 and 64.

Here, the electromagnetic directional control valve 52 controls the pressure in the power pressure chamber of the booster 10 in which the pressure corresponding to the depression force of the brake pedal 14 is generated during the anti-lock control, and the high pressure regardless of the operation of the brake pedal 14 during the acceleration slip control. The accumulators 34 in which the hydraulic pressures are generated are communicated with the electromagnetic direction switching valves 50, respectively.

The electromagnetic directional control valve 50 controls the hydraulic pressure supplied via the electromagnetic directional control valve 52 for both the anti-lock control and the acceleration slip control.
It supplies to the electromagnetic hydraulic pressure control valves 54 and 56 which lead to 2,24. Therefore, high-pressure fluid is supplied to the three-way switching valves 54 and 56 only when the brake pedal 14 is depressed during the antilock control and always during the acceleration slip control.

The three-way switching valves 54 and 56 are also in communication with the reservoir tank 32, and supply the supplied high-pressure hydraulic pressure to the wheel cylinders 22 and 24 to increase the brake hydraulic pressure. 24 communicates with the reservoir tank 32 to reduce the brake oil pressure, or to shut off these passages together to maintain the brake oil pressure.

In the anti-lock control and the acceleration slip control for the rear wheels RL and RR in the automatic brake system of the present embodiment, the brake oil pressure is appropriately increased, reduced, and maintained, and the brake is applied when the braking force is excessive. When the hydraulic pressure is reduced, the rear wheels RL and R are actively driven when the driving force is excessive.
This is realized by braking R.

On the other hand, for the front wheels FL and FR, it is sufficient to perform only the antilock control, and therefore, a configuration different from that of the rear wheels RL and RR is employed as described above. More specifically, the electromagnetic directional control valves 58 and 66 are switched during the antilock control so that the wheel cylinders 26, 28 and 3
The three-way switching valve 6 communicates with the direction switching valves 66 and 68.
6, 68, the fluid passages 62, 64 communicate with the power chamber of the booster 10 to increase the brake hydraulic pressure, and communicate with the reserve tank 32 to reduce the pressure, and shut off the fluid passages 62, 64 to maintain the function. It is configured to fulfill.

In this case, during the antilock control, the brake hydraulic pressure of the wheel cylinders 26 and 28 is increased only when the brake pedal 14 is depressed and the power pressure chamber is appropriately pressurized, and the braking force becomes excessive. In this case, the brake oil pressure is released to the reserve tank 32, and the locked state of the wheels is released.

Incidentally, the pressure in the power pressure chamber is supplied to the pressure intensifier 30 through a liquid passage 70. The pressure booster 30 is a device provided to ensure a fail-safe function when the booster 10 does not function properly. When the pressure in the power pressure chamber is not normally increased,
The hydraulic pressure supplied via the proportioning bypass valve 20 is further increased by a built-in pressure increasing piston and supplied to the wheel cylinders 26, 28 of the front wheels FL, FR.

In the case of such an abnormality, antilock control,
An abnormal signal is transmitted from the differential pressure switch 74 to an ECU (Electronic Control Unit) 72 which controls the acceleration slip control, and thereafter, a measure is taken to prohibit execution of the antilock control and the acceleration slip control. A pressure limiter 76 is provided in the fluid passage 70. When the master cylinder fluid pressure is further increased after the power pressure reaches the defeat limit, the pressure limiter 76 is moved from the pressure intensifier 30 to the power pressure chamber. To prevent backflow of brake fluid to prevent pressure increase.

The ECU 72 is mainly composed of a computer, and includes the pressure sensor 42 and the pressure switch 4 described above.
4, each signal of the differential pressure switch 74 and the front wheels FL, FR,
Wheel speed, wheel deceleration, vehicle speed, etc. are calculated based on the detection results of the rotation speed sensors 78, 80, 82, 84 for detecting the respective rotation speeds of the rear wheels RL, RR, and anti-lock is performed based on the calculation results. Control and acceleration slip control are performed.

Incidentally, in the automatic brake device of the present embodiment, two systems of the liquid passages 16 and 1 for communicating the master cylinder 12 and the proportioning bypass valve 20 are provided.
2 and the liquid passage leading to the power pressure chamber of the booster 10
Change valves 86, 88, 9 for allowing high-pressure oil liquid out of the oil liquid supplied to the two oil liquid inlets to flow out from the oil liquid outlet.
Hydraulic pressure controlled by a spool type electromagnetic hydraulic pressure control valve 92 is supplied via the control valve 0.

The spool-type electromagnetic hydraulic pressure control valve 92 is a valve that controls the hydraulic pressure of the accumulator 34 to a level proportional to the supply current and supplies the hydraulic pressure, and is a device that controls the brake hydraulic pressure during automatic brake operation. That is, the spool type electromagnetic hydraulic pressure control valve 92 communicates the outlet connected to the wheel cylinder with the reservoir 32 to reduce the brake oil pressure, and communicates with the accumulator 34 to increase the brake oil pressure. The state is switched to a state in which the brake hydraulic pressure is maintained without communicating with any of them.

The change valves 86, 88,
A normally closed solenoid on-off valve 94 is provided between the spool 90 and the spool type electromagnetic hydraulic pressure control valve 92. The spool-type electromagnetic hydraulic control valve 92 and the electromagnetic on-off valve 94
It is controlled by a controller 100, which is a main part of the present embodiment, via drive circuits 96 and 98.

Here, the controller 100 includes an ECU
Vehicle speed information is supplied from 72, and distance information to an obstacle existing in front of the vehicle is supplied from an inter-vehicle distance detection device 102 constituted by a radar or the like that monitors the front of the vehicle in order to realize the distance measuring means 1. Have been.

The controller 100 executes the routine described below based on the information to appropriately control the spool type electromagnetic hydraulic pressure control valve 92 and the electromagnetic opening / closing valve 94 to thereby control the automatic brake mechanism 3 and the auxiliary This implements the braking force changing means 4.

In this case, the inter-vehicle distance detecting device 10
And the distance to the obstacle ahead of the vehicle detected by the ECU 2 and the ECU 7
If it is determined from the vehicle speed information and the like supplied from the vehicle 2 that there is no possibility of collision with a forward obstacle, no current is supplied to the spool-type electromagnetic hydraulic pressure control valve 92, and the solenoid in the shut-off state The on-off valve 94 is communicated with the reservoir tank 32.

Accordingly, under such circumstances, the brake pedal 1
If step 4 is depressed, change valves 86, 88, 90
Supplies the hydraulic pressure supplied from the master cylinder 12 to each of the wheel cylinders 22, 24, 26, and 28, and a braking force according to the driver's intention is generated on each wheel.

On the other hand, when the distance to the obstacle ahead detected by the inter-vehicle distance detecting device 102 is unduly short, as judged from the relative speed between the obstacle and the vehicle, the controller 100 exhibits a function as an automatic brake. Drive circuit 9
Issue appropriate control signals to 6,98. As a result,
To each of the change valves 86, 88 and 90, in addition to the hydraulic pressure of the master cylinder 12, an appropriate electric control hydraulic pressure adjusted by a spool type electromagnetic hydraulic control valve 92 is supplied.

Therefore, the change valves 86, 88, 90
If the master cylinder hydraulic pressure is higher than the electric control hydraulic pressure is supplied to the master cylinder hydraulic pressure, or if the electric control hydraulic pressure is higher than the master cylinder hydraulic pressure or the brake pedal 14 is not depressed, , The electric control hydraulic pressure is supplied to the wheel cylinders 22, 24, 26, 28. And, each wheel cylinder 22, 24, 26, 28
Exerts a braking force according to the supplied hydraulic pressure.

The automatic braking device according to the present embodiment automatically exerts the braking force necessary for avoiding a collision regardless of the state of the brake pedal 14 when the vehicle unduly approaches an obstacle ahead. It is to let.

By the way, the automatic brake is activated
This is usually the case when the driver is unaware that he or she has approached the obstacle ahead. Therefore, if sudden braking is performed suddenly without any warning, a transient shock is given to the driver, which is not preferable in terms of operating characteristics.

When it is necessary to stop the vehicle suddenly by the automatic braking, if the driver can be informed of the situation before the sudden braking, the shock as described above can be reduced. In some cases, the driver may take sufficient measures to avoid a collision by his own operation, and as a result, a sudden stop due to automatic braking may be avoided.

In view of this point, it is effective to perform preliminary braking for the purpose of informing the driver of the situation prior to performing actual braking for stopping the vehicle when operating the automatic brake. It is. Then, in order to give an effective perceptual effect to the driver, as shown in FIG.
It is empirically known that it is effective to generate a triangular-wave-shaped deceleration that ends in about 0.5 seconds as shown in FIG.

Here, taking the case of a disc brake as an example, the braking torque T generated on each wheel is represented by A, the effective area of the wheel cylinder, r the effective radius of the disc rotor, and the dynamic friction between the brake pad and the disc rotor. Assuming that the coefficient is μ, it can be expressed as follows with respect to the brake hydraulic pressure P supplied to the wheel cylinder.

T = 2μ × P × A × r (1) As described above, the braking torque T generated at each wheel is a value proportional to the brake oil pressure P. For this reason, when operating the automatic brake, as shown in FIG. 3B, a triangular wave-shaped electric control hydraulic pressure having an appropriate peak value is supplied from the spool type electromagnetic hydraulic control valve 92 to each of the wheel cylinders 22, 24,
If it supplies to 26 and 28, a driver can perceive that an automatic brake operates.

By the way, it is known that the sensitivity of a vehicle occupant to perceive the vibration generated in the vehicle has a correlation with the vehicle speed when the vibration occurs. For example, the vibration sensitivity of the occupant with respect to the triangular waveform deceleration as shown in FIG. 3A decreases as the vehicle speed increases as shown in FIG.

Therefore, if it is necessary to secure a level of α ₁ as the vibration sensitivity in order to secure a certain perceptual effect at the time of preliminary braking, if the vehicle speed is V ₁ , the peak value G ₁ is 3
Suffice triangular wave shape deceleration, but will be when the vehicle speed is V _2, it is necessary to perform preliminary braking with a peak value greater G ₂ than G _1.

Focusing on this point, the automatic brake device of this embodiment changes the electric control hydraulic pressure generated by the spool type electromagnetic hydraulic control valve 92 at the time of preliminary braking according to the vehicle speed as shown in FIG. It is characterized by the following points. still,
FIG. 5 shows an example in which the brake oil pressure at the time of the preliminary braking is set in three stages according to the vehicle speed. However, the changing method is not limited to this, and for example, a method of changing continuously is adopted. May be.

Hereinafter, the processing executed by the controller 100 to realize the preliminary braking oil pressure shown in FIG. 5 will be described with reference to the flowchart shown in FIG. Note that this routine is a routine that is started when it is detected that the automatic brake should be operated based on the following distance detected by the following distance detection device 102, and is described above when the controller 100 executes this routine. Preliminary braking force changing means 4 is realized.

When the routine shown in FIG. 6 is started, first, in step (hereinafter referred to as S) 100, the vehicle speed V supplied from the ECU 72 is read. Then, see if the vehicle speed V read advances to S102 is equal to or less than the low-speed determination value V _1. Here, if V ≦ V ₁ is not satisfied, furthermore, S10
Proceed to 4 is compared with the high-speed determination value V ₂ and the vehicle speed V.

In this way, whatever the current vehicle speed V is
Level is determined, and according to the level, V ≦ V₁In
If so, proceed to S106 to set the low pressure set value P.₁And V₁<V
≤V _TwoIn the case of, the process proceeds to S108 and the medium pressure set value P_TwoAnd
V_TwoIf <V, proceed to S110 to set the high pressure set value P
_ThreeAre respectively selected as the preliminary braking oil pressures P, and
End the process.

As a result, when the automatic brake is operated in accordance with the instruction from the controller 100, the higher the vehicle speed V, the larger the electric control hydraulic pressure is applied to the master cylinder 2 during the preliminary braking.
2, 24, 26, and 28, it is possible to cancel the characteristic of the vibration sensitivity shown in FIG. 4 and to generate a preliminary braking force that can surely make the driver perceive the operation of the automatic brake.

Incidentally, as shown in the above equation (1), the braking torque T generated on each wheel is controlled by the wheel cylinders 22,2.
Are proportional to the hydraulic pressure P supplied to 4, 26, 28,
If an appropriate oil pressure P is supplied, the braking torque T
Can be generated.

On the other hand, there is a relationship as shown in the following equation between the braking torque T and the deceleration G generated in the vehicle. Although both are in a proportional relationship, when the vehicle weight W and the tire radius R fluctuate, As a result, the proportionality constant changes.

G = T / (W × R) (2) In this case, the tire radius R hardly fluctuates due to its properties, and there is no problem. There is a problem because it fluctuates relatively easily and greatly due to the influence of luggage.

Therefore, in order to always provide the driver with the perceptual effect of the preliminary braking at a constant level, it is necessary to consider the influence of the vehicle weight W. The vehicle weight detection device 104 shown connected to the controller 100 in FIG.
Focuses on this point, and corresponds to the vehicle weight detecting means 5 described above.

Here, the vehicle weight detecting device 104 calculates the vehicle weight based on, for example, the average relative distance between the wheel and the vehicle body and the spring force of the suspension mechanism, and detects and obtains the distortion of the suspension mechanism. In the case where an air spring is used as the suspension or the suspension mechanism, the one determined based on the air pressure or the like can be applied.

FIG. 7 shows that the controller 100 executes the electric control hydraulic pressure corrected based on the vehicle weight W detected by the vehicle weight detection device 104 to supply the wheel cylinders 22, 24, 26 and 28 at the time of preliminary braking. 4 shows a flowchart of a routine. Note that, similarly to the routine shown in FIG. 6, the routine shown in FIG. 6 is a routine that is started when it is detected that the automatic brake should be activated based on the following distance detected by the following distance detecting device 102. , The controller 100 executes the above-described preliminary braking force changing means 4.

In the routine shown in FIG.
00 reads the standard vehicle weight W ₀ from the memory as the initial setting in. As shown in the above equation (2), the deceleration G of the vehicle is a function of the vehicle weight W, and the correction for eliminating the effect is based on a reference in which the relationship between the deceleration G and the braking torque T is known in advance. it is because to be executed in relation to the vehicle weight W _0.

After the reading of the reference vehicle weight W ₀ is completed in this way, the flow proceeds to S202, in which the vehicle speed V is read in the same manner as the routine shown in FIG. Read W. Then, FIG.
The vehicle speed V is determined in steps S206 and S208 as in the routine shown in FIG.
The process proceeds to one of steps 212 and S214.

These S210, S212 and S214 are:
A step of selecting the electric control hydraulic pressure P to be supplied to the wheel cylinders 22, 24, 26 at the time of preliminary braking according to the detected vehicle speed V, and correcting the set hydraulic pressure by the detected vehicle weight W, which is a characteristic part of this routine. It is.

That is, the reference hydraulic pressure selected in relation to the vehicle speed V is the same as the electric control hydraulic pressure shown in FIG. 6, and if V ≦ V ₁ , the low pressure set value P ₁ (S210)
When V ₁ <V ≦ V ₂ , the medium pressure set value P ₂ (S212),
If V ₂ <V, the high pressure set value P ₃ is selected as the preliminary braking oil pressure P. In each of these steps, the electric control hydraulic pressure P is calculated by multiplying the selected P ₁ , P ₂ , P ₃ by a correction coefficient of W / W ₀ .

According to the electric control hydraulic pressure P set by performing such a correction, the braking torque T during G = T / (W × R) fluctuates according to the fluctuation of the vehicle weight W. A constant deceleration will always be obtained.

For this reason, when the controller 100 adopts the processing of this routine, the deceleration generated at the time of the preliminary braking is not affected not only by the vehicle speed V but also by the vehicle weight W, and the appropriate vibration sensitivity α is always obtained. As a result, the driver can reliably perceive the operation of the automatic brake.

[0071]

As described above, according to the first aspect of the present invention, the same shock can always be given to the driver by the preliminary braking regardless of the vehicle speed. For this reason, unlike the conventional automatic braking device in which the preliminary braking force is constant, it has a feature that in the entire driving range of the vehicle, the driver can perceive the start of the operation of the automatic braking to encourage mental and physical preparation. ing.

According to the second aspect of the present invention, when the vehicle weight changes due to the influence of the number of passengers, the load weight, and the like, the preliminary braking force is corrected according to the change. Regardless of the change, an appropriate deceleration is always obtained at the time of preliminary braking, and it has a feature that a perceptual effect can be more reliably exerted on the driver as compared with the automatic braking device of the first aspect.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating a state of deceleration that occurs when the automatic brake device of the present embodiment performs preliminary braking.

FIG. 4 is a diagram illustrating a relationship between a vehicle speed and a vibration sensitivity that a passenger of the vehicle perceives with the same deceleration vibration.

FIG. 5 is a diagram illustrating a state of a preliminary braking hydraulic pressure of the automatic brake device according to the present embodiment.

FIG. 6 is a flowchart of an example of a routine executed by a controller of the automatic brake device according to the present embodiment.

FIG. 7 is a flowchart of another example of the routine executed by the controller of the automatic brake device according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distance measuring means 2 Brake mechanism 3 Automatic brake mechanism 4 Preliminary braking force changing means 5 Vehicle weight detecting means 22, 24, 26, 28 Wheel cylinder 34 Accumulator 36 Motor 38 Pump 72 Electronic control unit (ECU) 86, 88, 90 Change Valve 92 Spool type electromagnetic hydraulic pressure control valve 100 Controller 102 Inter-vehicle distance detecting means 104 Vehicle weight detecting device

Continuation of front page (56) References JP-A-54-40432 (JP, A) JP-A-51-31422 (JP, A) JP-A-64-28060 (JP, A) JP-A-4-362453 (JP) , A) JP-A-6-1221 (JP, A) JP-A-5-72629 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 7/12

Claims (2)

(57) [Claims] 1. A distance measuring device for measuring a distance to an obstacle ahead of a vehicle.
Determine the possibility of a collision based on the measurement results of the
If the distance is not secured, there is no
In relation to the wheel brake mechanism prescribed brake oil pressure
Is a mechanism that activates the automatic brake by supplying
Before performing the final braking for both decelerations,
The purpose is to let the driver know that the rake is working
Automatic brake equipped with an automatic brake mechanism
In rake equipment,The preliminary braking force during the preliminary braking is varied based on the vehicle speed.
In addition to providing braking force changing means, The vehicle speed at the time of starting the preliminary braking by the preliminary braking force changing means.
Configuration in which the preliminary braking force is greatly changed as the vehicle speed increases
Made An automatic braking device, characterized in that: 2. The automatic braking device according to claim 1, further comprising a vehicle weight detecting unit that detects a vehicle weight, wherein the preliminary braking force changing unit corrects the braking force during the preliminary braking according to the vehicle weight. An automatic braking device, characterized in that: