JPH0769188A - Automatic brake device - Google Patents

Abstract

PURPOSE:To inform a driver of the operation start of an automatic brake in all the operation regions, by installing an auxiliary brake power varying means for varying proportionately to vehicle speed the brake power in the auxiliary brake application which is carried out before the main brake application. CONSTITUTION:When a between-vehicle distance detecting device 102 detects that the distance from an obstacle ahead is exceedingly short, a controller 100 transmits control signals to driving circuits 96 and 98. Accordingly, the electrically controlled hydraulic pressure which is adjusted by a spool type electromagnetic hydraulic control valve 92 is supplied into change valves 86, 88 and 90, added with the hydraulic pressure of a master cylinder 12. The electrically controlled hydraulic pressure is supplied to wheel cylinders 22, 24, 26, and 28, and brake acts automatically. In this case, before the main brake application, the tirangular wave-shaped electrically controlled hydraulic pressure having a proper peak value is used for the auxiliary brake application, and the electromagnetic wave hydraulic pressure control valve 92 is generated. In a controller 100, the hydraulic pressure at this time is set to the larger value when the car speed sent from an ECU72 is higher, and the always equal impact is applied to the driver.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in order to improve the safety of a vehicle, the front of the vehicle is monitored by a radar or the like, and the brake is automatically actuated when an obstacle ahead of the vehicle and the vehicle are improperly approached. Devices for avoiding collisions are known. If the brake device mounted on the vehicle has such a function, for example, it is possible to prevent a driver's inattentive driving and a rear-end collision accident due to carelessness, which is effective in improving safety.

By the way, when the automatic brake is actuated, it is usual that the driver does not perceive that the vehicle is improperly approaching a front obstacle. Therefore, if sudden braking is performed by the automatic braking, this is an unexpected shock to the driver and may cause an excessive shock.

Japanese Patent Laid-Open Publication No. 54-40432 pays attention to such a point, and when the automatic brake is operated, the driver is made to perceive that the automatic brake is operated prior to the main braking intended to decelerate the vehicle. Therefore, a brake device for performing preliminary braking is disclosed. In this case, the driver can predict that the next rapid braking will be performed by the preliminary braking,
In addition to being able to prepare for the sudden braking, it becomes possible to perceive some abnormal approach to an obstacle ahead and take some action by himself.

[0005]

However, empirically, when a temporary deceleration occurs in a vehicle, if the deceleration is equivalent, the deceleration is perceived as a larger impact as the vehicle speed decreases. Known to. Therefore, the driver of the vehicle perceives a relatively small deceleration during low-speed traveling, but the phenomenon is not perceived unless the deceleration is relatively large during high-speed traveling.

On the other hand, the above-mentioned conventional automatic brake device executes preliminary braking so that the operation thereof can be perceived prior to the main braking by the automatic braking, but the braking force during the preliminary braking (hereinafter referred to as the preliminary braking force). ) Is the same at high speed and at low speed. For this reason, there is a problem in that, although the perceptual effect is appropriately exerted on the driver under a condition where the vehicle speed is relatively low, the perceptual effect is not exerted properly at high speed running.

The present invention has been made in view of the above points, and in performing the preliminary braking prior to the main braking by the automatic brake, the above-mentioned problem is solved by changing the preliminary braking force as the vehicle speed increases. An object is to provide an automatic braking device that can be solved.

[0008]

FIG. 1 is a block diagram showing the principle of an automatic braking device that achieves the above object. That is, the above-mentioned purpose is to judge the possibility of collision based on the measurement result of the distance measuring means 1 for measuring the distance to the obstacle in front of the vehicle as shown in FIG. 1, and when the safe distance is not secured. Is a mechanism for supplying a predetermined brake hydraulic pressure to the brake mechanism 2 of the wheel to operate an automatic brake irrespective of the driver's intention, and prior to the main braking intended to decelerate the vehicle, In an automatic braking device including an automatic braking mechanism 3 for performing preliminary braking for the purpose of informing a driver that the automatic braking is activated, the braking force during the preliminary braking is changed to a greater extent as the vehicle speed becomes higher. This is achieved by an automatic braking device including the preliminary braking force changing means 4.

Further, in the automatic brake device having the above structure, the vehicle weight detecting means 5 for detecting the 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. The automatic braking device is effective for securing a more reliable perceptual effect.

[0010]

In the automatic braking device according to the present invention, when the automatic braking mechanism 3 determines that the distance to the front obstacle measured by the distance measuring means 1 is shorter than the predetermined determination distance and there is a possibility of collision. , Start the automatic brake operation to avoid 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 largely changed by the preliminary braking force changing means 4 as the vehicle speed increases. Therefore, the impact on 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 exhibited.

Further, 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 eliminated from the deceleration generated during the preliminary braking. Therefore, the deceleration that can always exert an appropriate perceptual effect is secured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the overall construction of an automatic braking device which is an embodiment of the present invention.

In the figure, 10 is a hydraulic booster (hereinafter,
12 is a tandem brake master cylinder (hereinafter simply referred to as a master cylinder).
Is. The master cylinder 12 includes therein a first pressurizing piston and a second pressurizing piston which are displaced in conjunction with the brake pedal 14, and when the brake pedal 14 is depressed, hydraulic pressure is generated.

The hydraulic pressure generated by the displacement of the first pressurizing piston and the second pressurizing piston is proportional to the proportioning bypass valve 2 by the liquid passages 16 and 18, respectively.
Lead to zero. The hydraulic pressure generated by the first pressurizing piston is applied to the wheel cylinders 22 and 24 of each brake 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. It is connected to the wheel cylinders 26, 28 of each brake.

That is, the automatic brake device of the present embodiment is of the front and rear two system type, and each of the wheel cylinders 22, 24,
26 and 28 correspond to the brake mechanism 2 described above.
In this vehicle, the left and right rear wheels RL and RR are drive wheels.

Proportioning bypass valve 20
When 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 are used.
The hydraulic pressure supplied to 2, 24 is reduced at a constant ratio to the hydraulic 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 increased by the first pressurizing piston is supplied to the wheel cylinders 22 and 24 of the rear wheels RL and RR without reducing the pressure. .

A pressure booster 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 increased by the second pressurizing piston of the master cylinder 12, and its role will be described later.

The first pressurizing chamber and the second pressurizing chamber in which the first pressurizing piston and the second pressurizing piston of the master cylinder 12 respectively generate hydraulic pressure are the first pressurizing piston and the second pressurizing piston. When the pressurizing piston is not depressed, it is in communication with the reserve tank 32. Therefore, when the brake fluid becomes insufficient, the brake fluid is appropriately replenished from the reserve tank 32 toward the master cylinder 12 during non-braking.

The booster 10 is provided integrally with the master cylinder 12 so as to boost the pedaling force of the brake pedal 14 and transmit it to the first and second pressurizing pistons. That is, inside the booster 10, there is formed a power pressure chamber that is switched from a state in which it communicates with the reservoir tank 32 to a state in which it communicates with the accumulator 34 by depressing the brake pedal 14.

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 is arranged in the power pressure chamber. Therefore, when the brake pedal 14 is depressed,
The high-pressure liquid pressure supplied via the accumulator 34 is applied to the power piston that has been released to the internal pressure of the reservoir tank 32.

Then, the first pressurizing piston and the second pressurizing piston of the master cylinder 12 are moved forward, and the hydraulic pressure is transmitted to the wheel cylinders 22, 24, 26, 28. It should be noted that the power chamber is configured so as not to communicate with the accumulator 34 or the reservoir tank 32 when the pedaling force of the brake pedal 14 and the reaction force are balanced. For this reason, when the depression amount of the brake pedal 14 becomes stable, the boost force is maintained at a constant value thereafter.

The hydraulic pressure boosted by a pump 38 driven by a motor 36 is supplied to the accumulator 34 via a check valve 40. At this time, the accumulator 34
The hydraulic pressure is maintained in a constant range by controlling the start / stop of the motor 36 based on the output signal of the pressure sensor 42.

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

Here, the automatic brake device of the present embodiment is
If excessive braking force is generated, the wheel cylinders 22, 2
The anti-lock control for releasing the brake oil pressure supplied to the wheels 4, 26, 28 to unlock the wheels, and when an excessive driving force is generated, a braking force is generated on the driving wheels to prevent the wheels from idling. It is configured on the premise that the acceleration slip control for converging 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 are an electromagnetic directional control valve 50 and a three-position directional control valve 3. Direction switching valves 54 and 56
In addition, the pressure booster 30 and the wheel cylinder 2 of the front wheels FL and FR
Two electromagnetic directional control valves 58 and 60 are provided between the control valves 6 and 28.

The electromagnetic directional control valve 50 on the rear wheels RL, RR side 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 valves on the front wheels FL, FR sides are connected. The switching valves 58, 60 are connected to the three-way switching valves 66, 68 via liquid passages 62, 64.

Here, the electromagnetic directional control valve 52 is in the power pressure chamber of the booster 10 in which a pressure corresponding to the pedaling force of the brake pedal 14 is generated during antilock control, and is high in pressure regardless of the operation of the brake pedal 14 during acceleration slip control. The accumulators 34 that generate the hydraulic pressure 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 during the anti-lock control and the acceleration slip control so as to reduce the hydraulic pressure.
It is supplied to the electromagnetic hydraulic pressure control valves 54 and 56 which communicate with Nos. 2 and 24. Therefore, high pressure hydraulic pressure 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, 56 are also in communication with the reservoir tank 32, and supply the supplied high-pressure hydraulic pressure to the wheel cylinders 22, 24 to increase the brake hydraulic pressure, or the wheel cylinders 22, 24. 24 functions to communicate with the reservoir tank 32 to reduce the brake hydraulic pressure, or to block these passages together to maintain the brake hydraulic pressure.

The anti-lock control and the acceleration slip control for the rear wheels RL and RR in the automatic brake device of the present embodiment appropriately execute such pressure increase, pressure decrease and holding of the brake hydraulic pressure and brake when the braking force is excessive. The hydraulic pressure is reduced, and when the driving force is excessive, the rear wheels RL and R that are the driving wheels are positively driven.
It is realized by braking R.

On the other hand, for the front wheels FL and FR, it is sufficient to perform only the anti-lock control, so that the configuration different from the system of the rear wheels RL and RR is adopted as described above. Specifically, at the time of antilock control, the electromagnetic direction switching valves 58 and 66 are switched to switch the wheel cylinders 26, 28 and 3 to each other.
3 way switching valve 6 communicating with direction switching valves 66 and 68
6, 68 connect the liquid passages 62, 64 to the power chamber of the booster 10 to increase the brake hydraulic pressure, communicate with the reserve tank 32 to reduce the pressure, and shut off the liquid passages 62, 64 to provide a holding function. It is configured to fulfill.

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

By the way, the pressure of the power pressure chamber is supplied to the pressure boosting device 30 through the liquid passage 70. The pressure boosting device 30 is a device provided to ensure a fail-safe function when the booster 10 does not function normally, and 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 booster piston and supplied to the wheel cylinders 26, 28 of the front wheels FL, FR.

When such an abnormality occurs, antilock control,
Further, an abnormal signal is transmitted from the differential pressure switch 74 to the ECU (electronic control unit) 72 that controls the acceleration slip control, and thereafter, the antilock control and the acceleration slip control are prohibited from being executed. A pressure limiter 76 is provided in the liquid passage 70, and when the master cylinder hydraulic pressure is further increased after the power pressure reaches the defeat limit, the pressure limiter 76 moves from the pressure booster 30 to the power pressure chamber. Prevents reverse flow of brake fluid to and prevents pressure buildup.

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 speeds, wheel decelerations, vehicle body speeds, etc. are calculated based on the detection results of the rotation speed sensors 78, 80, 82, 84 that detect the respective rotation speeds of the rear wheels RL, RR, and antilock is performed based on the calculation results. Control and acceleration slip control are performed.

By the way, in the automatic brake device of this embodiment, the two fluid passages 16 and 1 for connecting the master cylinder 12 and the proportioning bypass valve 20 are connected.
8 and 2 in the liquid passage leading to the power pressure chamber of the booster 10.
Change valves 86, 88, 9 for causing high-pressure oil liquid out of the oil liquids supplied to the two oil liquid inlets to flow out from the oil liquid outlets
The hydraulic pressure controlled by the spool-type electromagnetic hydraulic pressure control valve 92 is supplied via 0.

The spool type electromagnetic hydraulic pressure control valve 92 is a valve for controlling and supplying the hydraulic pressure of the accumulator 34 to a height proportional to the supply current, and is a device for controlling the brake hydraulic pressure during the automatic braking operation. That is, the spool-type electromagnetic hydraulic control valve 92 has a state in which an outlet connected to the wheel cylinder side communicates with the reservoir 32 to reduce the brake hydraulic pressure, and a state in which the spool hydraulic electromagnetic control valve 92 communicates with the accumulator 34 to increase the brake hydraulic pressure. It 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 electromagnetic on-off valve 94 is provided between 90 and the spool-type electromagnetic hydraulic pressure control valve 92. The spool type electromagnetic hydraulic pressure control valve 92 and the electromagnetic opening / closing valve 94 are
It is controlled by the controller 100, which is the main part of this embodiment, via the drive circuits 96 and 98.

Here, the controller 100 includes an ECU
The vehicle speed information is supplied from 72, and the distance information to the obstacle existing in front of the vehicle is supplied from the inter-vehicle distance detecting device 102 composed of a radar or the like that monitors the front of the vehicle to realize the distance measuring means 1 described above. Has been done.

Then, the controller 100 executes the below-mentioned routine on the basis of these pieces of information to appropriately control the spool-type electromagnetic hydraulic pressure control valve 92 and the electromagnetic opening / closing valve 94, and thereby the above-mentioned automatic brake mechanism 3 and the backup. The braking force changing means 4 is realized.

In this case, the inter-vehicle distance detecting device 10
2 and the distance to the front obstacle detected by the ECU 7
When it is determined from the vehicle speed information supplied from 2 that there is no possibility of collision with an obstacle ahead, no current is supplied to the spool-type electromagnetic hydraulic control valve 92, and the electromagnetic valve in the shut-off state is not supplied. The open / close valve 94 is communicated with the reservoir tank 32.

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

On the other hand, if the distance to the front obstacle detected by the inter-vehicle distance detecting device 102 is judged to be unreasonably close based on the relative speed between the obstacle and the vehicle, the controller 100 functions as an automatic brake. Drive circuit 9
6. Issue appropriate control signals to 6,98. As a result,
In addition to the hydraulic pressure of the master cylinder 12, an appropriate electric control hydraulic pressure adjusted by the spool type electromagnetic hydraulic pressure control valve 92 is supplied to each change valve 86, 88, 90.

Therefore, the change valves 86, 88, 90
If a master cylinder hydraulic pressure 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 if the brake pedal 14 is not depressed. Electrically controlled hydraulic pressure is supplied to the wheel cylinders 22, 24, 26, 28. Then, each wheel cylinder 22, 24, 26, 28
Shows a braking force according to the supplied hydraulic pressure.

When the vehicle improperly approaches an obstacle ahead of the vehicle, the automatic braking device of the present embodiment automatically exerts the braking force necessary for avoiding a collision regardless of the state of the brake pedal 14 in this way. It is what makes me.

By the way, the automatic brake works
Normally, this is the case when the driver is not aware that he has approached the obstacle ahead of him improperly. Therefore, if sudden braking is applied suddenly without any warning, a transient shock is given to the driver, which is not preferable in terms of operating characteristics.

Further, when it is necessary to stop the vehicle suddenly by the automatic braking, if the driver can be surely informed of the situation before the sudden braking, the shock as described above is alleviated. In some cases, the driver may take sufficient measures to avoid a collision by himself / herself, 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 notifying the driver of the situation prior to the main braking for stopping the vehicle when operating the automatic brake. Is. Then, in order to give an effective sensory effect to the driver, pre-braking is performed as shown in FIG.
It is empirically known that it is effective to generate a triangular wave-shaped deceleration that ends in, for example, about 0.5 sec, as shown in (A).

Taking the case of a disc brake as an example, the braking torque T generated in each wheel is such that the effective area of the wheel cylinder is A, the effective radius of the disc rotor is r, and the dynamic friction between the brake pad and the disc rotor. When the coefficient is μ, the brake hydraulic pressure P supplied to the wheel cylinder can be expressed as follows.

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

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 to the triangular wave-shaped deceleration as shown in FIG. 3 (A) decreases as the vehicle speed increases, as shown in FIG.

Therefore, if it is necessary to secure the level of α ₁ as the vibration sensitivity in order to secure a reliable perceptual effect during the preliminary braking, if the vehicle speed is V ₁ , the peak value G ₁ is 3
Although the angular wave shape deceleration is sufficient, when the vehicle speed is V _2, it is necessary to perform pre-braking with a peak value of G ₂ larger than G ₁ .

Focusing on this point, the automatic brake device of the present embodiment changes the electric control hydraulic pressure generated by the spool type electromagnetic hydraulic pressure control valve 92 during pre-braking in accordance with the vehicle speed as shown in FIG. It is characterized by the point. still,
FIG. 5 shows an example in which the brake hydraulic pressure at the time of preliminary braking is set in three stages according to the vehicle speed, but the changing method is not limited to this and, for example, a stepless changing method is adopted. You may.

The processing executed by the controller 100 to realize the preliminary braking hydraulic pressure shown in FIG. 5 will be described below with reference to the flowchart shown in FIG. It should be noted that this routine is a routine that is started when it is detected that the automatic brake should be actuated based on the inter-vehicle distance detected by the inter-vehicle distance detection device 102, and the controller 100 executes the present routine to perform the above-mentioned routine. The 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, in S102, it is determined whether the read vehicle speed V is equal to or lower than the low speed judgment value V ₁ . If V ≦ V ₁ is not satisfied here, S10 is further set.
Then, the procedure proceeds to step 4 to compare the high speed judgment value V ₂ with the vehicle speed V.

In this way, what is the current vehicle speed V?
It is determined whether it is in the level, and V ≦ V according to the level₁And
If so, proceed to S106 and set the low pressure P₁To V₁<V
≤V ₂In the case of, the process proceeds to S108 and the intermediate pressure set value P₂The
V₂If <V, proceed to S110 and set high pressure P
₃Are selected as the preliminary braking oil pressures P, and
End the reason.

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 becomes during the pre-braking.
2, 24, 26, and 28, the characteristics of the vibration sensitivity shown in FIG. 4 can be canceled to generate a preliminary braking force that can surely make the driver perceive the operation of the automatic brake.

By the way, the braking torque T generated in each wheel as shown in the equation (1) is determined by the wheel cylinders 22 and 2.
Is proportional to the hydraulic pressure P supplied to 4, 26, 28,
If an appropriate hydraulic pressure P is supplied, the braking torque T corresponding to that is supplied.
Can be generated.

On the other hand, the braking torque T and the deceleration G generated in the vehicle have a relationship as shown in the following equation. Although the two are in a proportional relationship, when the vehicle weight W and the tire radius R change, As a result, the proportional constant changes.

G = T / (W × R) (2) In this case, the tire radius R hardly changes due to its nature and there is no problem, but the vehicle weight W does not affect the passengers or the load. There is a problem because it is relatively easy and changes significantly due to the effect of luggage.

Therefore, it is necessary to consider the influence of the vehicle weight W in order to always give the driver a perceptual effect of the preliminary braking at a constant level. The vehicle weight detection device 104 connected to the controller 100 in FIG.
Pays attention to such a point, and corresponds to the vehicle weight detection means 5 described above.

Here, the vehicle weight detecting device 104 calculates the vehicle weight based on 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 mechanism, the one obtained based on the air pressure can be applied.

In FIG. 7, the controller 100 executes to supply the electric control hydraulic pressure corrected based on the vehicle weight W detected by the vehicle weight detecting device 104 to the wheel cylinders 22, 24, 26 and 28 during pre-braking. The flowchart of a routine is shown. Note that the routine shown in the same drawing is also a routine that is started when it is detected that the automatic brake should be operated from the inter-vehicle distance detected by the inter-vehicle distance detecting device 102, similarly to the routine shown in FIG. The controller 100 executes the above-mentioned preliminary braking force changing means 4 so as to realize it.

In the routine shown in FIG. 7, first, S2
At 00, the reference vehicle weight W ₀ is read from the memory as an initial setting. 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 influence thereof is based on the relationship that the relationship between the deceleration G and the braking torque T is known in advance. This is because it should be executed in relation to the vehicle weight W ₀ .

After the reference vehicle weight W ₀ is read in this way, the flow proceeds to S202 to read the vehicle speed V as in the routine shown in FIG. Read W. Then, as shown in FIG.
The level of the vehicle speed V is discriminated in S206 and S208 as in the routine shown in FIG.
The process proceeds to either step 212 or S214.

These S210, S212 and S214 are
This is a characteristic part of this routine, and a step of selecting an electric control hydraulic pressure P to be supplied to the wheel cylinders 22, 24, 26 during pre-braking in accordance with the detected vehicle speed V and correcting the set hydraulic pressure by the detected vehicle weight W. Is.

That is, the reference hydraulic pressure selected in relation to the vehicle speed V is the same as the electrically controlled hydraulic pressure shown in FIG. 6, and when V ≦ V ₁ , the low pressure set value P ₁ (S210),
When V ₁ <V ≦ V ₂ , medium pressure set value P ₂ (S212),
When V ₂ <V, the high pressure set value P ₃ is selected as the preliminary braking hydraulic pressure P. Then, in each of these steps, the electric control hydraulic pressure P is calculated by multiplying the selected P ₁ , P ₂ , and P ₃ by the correction coefficient 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) changes in accordance with the change in the vehicle weight W, and eventually, A constant deceleration will always be obtained.

Therefore, when the controller 100 adopts the processing of this routine, the deceleration that occurs during pre-braking is not affected by not only the vehicle speed V but also the vehicle weight W, and an appropriate vibration sensitivity α is always provided. As a result, the driver can be made sure to perceive the operation of the automatic brake.

[0071]

As described above, according to the first aspect of the present invention, it is possible to always give the same impact to the driver by the preliminary braking regardless of the vehicle speed. Therefore, unlike the conventional automatic braking device in which the preliminary braking force is constant, it has a feature that the driver can perceive the start of the operation of the automatic braking in all the driving regions of the vehicle to prompt mental and physical preparation. ing.

According to the second aspect of the present invention, when the vehicle weight changes due to the number of passengers, the weight of the vehicle, etc., the preliminary braking force is corrected according to the change. An appropriate deceleration is always obtained during pre-braking regardless of changes, and compared with the automatic braking device according to claim 1, there is a feature that the perceptual effect for the driver can be more reliably exhibited.

[Brief description of drawings]

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

FIG. 2 is an overall configuration diagram of an automatic braking device that is an embodiment of the present invention.

FIG. 3 is a diagram illustrating a state of deceleration that occurs in the automatic braking device according to the present embodiment during preliminary braking.

FIG. 4 is a diagram illustrating a relationship between a vehicle speed and a vibration sensitivity that an occupant of a vehicle feels with respect to vibration of the same deceleration.

FIG. 5 is a diagram showing a state of 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 the controller of the automatic braking device according to the present embodiment.

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

[Explanation of symbols]

 1 Distance measuring means 2 Brake mechanism 3 Automatic braking 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 detection means 104 Vehicle weight detection device

Claims (2)

[Claims] 1. A possibility of a collision is judged based on a measurement result of a distance measuring means for measuring a distance to an obstacle ahead of the vehicle, and it is irrelevant to a driver's intention when a safe distance is not secured. It is a mechanism that supplies a predetermined brake hydraulic pressure to the wheel brake mechanism to activate the automatic brake, and that the automatic brake is activated prior to the main braking intended to decelerate the vehicle. In an automatic braking device provided with an automatic braking mechanism for performing preliminary braking for the purpose of informing, the preliminary braking force changing means for changing the braking force during the preliminary braking to a greater extent as the vehicle speed is higher. And an automatic braking device. 2. The automatic braking device according to claim 1, further comprising a vehicle weight detecting means for detecting a vehicle weight, wherein the preliminary braking force changing means corrects the braking force at the preliminary braking according to the vehicle weight. An automatic braking device characterized in that