JP2003306137A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a vehicle from being in an unstable state, in a brake control device equipped with an assist brake device. <P>SOLUTION: When a brake pedal is depressed, regenerative braking force is generated by a motor generator provided on a wheel, and an auxiliary hydraulic brake is actuated to make a required braking force calculated by a depression state. The size of braking torque gradient η in regard to slip speed reflecting a friction state between the wheel and a road surface calculated by wheel speed is determined. If η is smaller than a prescribed value KA, an allowance degree getting to a wheel locking state is regarded as small, the required braking force is corrected to be decreased, and the braking pressure of the auxiliary hydraulic brake is decreased on the basis of the corrected required braking force. Therefore, the braking force is decreased before getting to the wheel locking state, and an unstable state of a vehicular body can be avoided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device equipped with an assist brake device.

[0002]

2. Description of the Related Art Conventionally, there has been provided an assist (auxiliary) brake device in order to supplement the braking force of a main brake device to generate a larger braking force. For example, when the regenerative braking device in an electric vehicle or a hybrid vehicle is used as the main braking device, the hydraulic braking device is used as the auxiliary braking device, or the brake hydraulic pressure generated by the main hydraulic braking device is used in small trucks and passenger cars. In addition, there is an assist brake device that increases the wheel cylinder pressure with a hydraulic pump.

In a brake control device equipped with such an assist braking device, when the occupant operates a brake pedal to suddenly apply a braking force, a braking force equal to or higher than the maximum braking force generated by the main braking device is applied to the assist braking device. Since it can be generated by addition, the braking stop distance can be greatly shortened.

However, when the friction coefficient of the road surface is low, that is, when the road surface is slippery (low μ road), when the brake assist is performed in the same manner as when the friction coefficient of the road surface is high, the vehicle body motion may slip. Instability may occur. Such an unstable state of the vehicle at the time of brake assist cannot be completely eliminated even in a vehicle equipped with an ABS device because the ABS operates at the limit where slip occurs.

In view of the above points, an object of the present invention is to prevent a vehicle from becoming unstable in a brake control device equipped with an assist brake device.

[0006]

In order to achieve the above object, the invention as set forth in claim 1 is a brake control device for generating a braking force between a wheel and a road surface by a brake operation of a driver. Brake operation amount detecting means for detecting a brake operation amount related to operation, and required braking force calculating means for calculating a required braking force as a braking force to be generated based on the detected brake operation amount,
A first braking force generating means for generating a first braking force on the wheel by the brake operation, and a second braking force generated on the wheel by the brake operation by adding a second braking force to the first braking force. 2 braking force generating means, a wheel speed sensor for detecting a wheel speed, a braking margin calculating means for calculating a braking torque gradient with respect to a slip speed based on the detected wheel speed, and the request based on the braking torque gradient. Required braking force correction means for correcting the braking force, and the second braking force generation means generates the second braking force based on the corrected required braking force.

According to the present invention, the required braking force determined according to the braking operation is corrected according to the magnitude of the braking torque gradient reflecting the frictional state between the wheel and the road surface calculated based on the wheel speed, The generated braking force of the second braking force generating means is corrected without changing the first braking force so as to obtain the corrected required braking force. Therefore, even if the frictional state between the wheel and the road surface changes, it is possible to prevent the unstable behavior of the vehicle body and to generate the braking force on the wheel.

According to a second aspect of the present invention, the required braking force correction means reduces the required braking force when the braking torque gradient becomes a predetermined value or less.

According to the present invention, when the braking torque gradient becomes smaller than a predetermined value, it can be considered that the margin to reach the wheel lock state is small. Therefore, before the wheel lock state is reached, the brake operation is performed in advance. It is possible to prevent the occurrence of unstable behavior of the vehicle body by correcting the required braking force determined according to the above.

The demanded braking force correcting means may correct the difference between the calculated demanded braking force and the first braking force as described in claim 3, or, As described in claim 4, it does not matter if the calculated required braking force is corrected with respect to the amount corresponding to the second braking force.

Further, as described in claim 5, the second braking force generating means applies hydraulic pressure to the wheel cylinder of the wheel by the brake operation, thereby applying the second braking force to the wheel rotation. Auxiliary hydraulic braking means can be used.

Further, as described in claim 6, the first braking force generating means is driven by the rotation of the wheel to convert the rotational force into electric energy, so that the first wheel is rotated. The first braking force is applied to the wheel rotation by using a regenerative braking means for applying a braking force, or by applying hydraulic pressure to the wheel cylinder of the wheel by the braking operation as described in claim 7. Either hydraulic braking means may be used.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. Figure 1
Two brake wheels (for example, two front wheels or two rear wheels) of the brake control device 1 of the first embodiment in which the present invention is applied to a hybrid vehicle.
FIG. 3 is a diagram showing a configuration of a hydraulic circuit for wheels, or a front right wheel, a rear left wheel, and the like.

As shown in FIG. 1, a master cylinder (hereinafter referred to as M / C) 12 for generating a brake fluid pressure by depressing a brake pedal 11 is provided, and M / C1
Two pipe systems connected to the wheel cylinders (hereinafter, referred to as W / C) 18 of the two wheels are connected to 2 via the linear adjustment valve 16. The opening of the linear adjustment valve 16 is linearly controlled by a command value of the brake control ECU 10, and is in a communication state when the brake operation is not performed and when the normal brake operation is performed. The opening control is performed in the hydraulic brake operation when the braking force is reduced and corrected.

A pressure sensor 15 for detecting the discharge pressure of the M / C 12 is provided between the M / C 12 and the linear adjusting valve 16.

A pressure increasing control valve 17 which is an N / O (normally open) valve is arranged between the linear adjusting valve 16 and each W / C 18. A pressure reducing control valve 20, which is an N / C (normally closed) valve for releasing the hydraulic pressure of the W / C 18, is connected between the W / C 18 and the pressure increasing control valve 17, and the pressure reducing control valve 2
A reservoir 21 is connected to the downstream side of 0.

Further, the pressure reducing control valve 20 and the reservoir 21 are connected to between the linear adjusting valve 16 and the pressure increasing control valve 17 via a pump 22 and a damper 24 driven by a motor 23. . Further, the reservoir 21 is M
/ C12 is connected.

The linear adjusting valve 16, the pressure increasing control valve 17, and the pressure reducing control valve 20 are electromagnetic two-position valves having a communicating position and a shut-off position, so that the communicating position and the shut-off position can be changed by energization. In addition, the pressure difference between the upstream and downstream of each valve can be adjusted according to the amount of electricity. The amount of electricity supplied to the pressure increase control valve 17 and the pressure reduction control valve 20 is linearly current controlled by a brake control ECU 10 described later. The linear current control referred to here includes PWM control that changes the voltage DUTY ratio that drives the solenoid valve and changes the effective current.

The above hydraulic circuit corresponds to the second braking force generating means of the present invention.

A wheel speed sensor 25 of an electromagnetic pickup type or an electric resistance element type is arranged on each wheel 19, and this generates a pulse signal according to the rotation of each wheel 19.
The wheel speed sensor 25, the pressure sensor 15, and other various sensor signals necessary for brake control are brake control EC.
Input to U10.

The brake control ECU 10 includes a CPU and RO.
A well-known microcomputer having M, RAM, and I / O generates control signals for controlling the linear valves 16, 17, 20 and the motor 23 included in the brake control device 1 based on the detection signals. This control signal is applied to each wheel 1
The pressure-increasing output, the holding output, and the pressure-decreasing output generated for each 9 are determined.

Further, each wheel 19 is provided with a motor generator 27 for driving and regeneratively braking the wheel, and the regenerative control ECU 26 causes the motor generator 2 to operate.
7 drive control and regenerative braking control are performed. Particularly, the regenerative braking control is performed by the brake control ECU 10 and the regenerative control EC.
Performed in collaboration with U26. The regenerative control ECU 26
Is composed of a microcomputer.

In the first embodiment thus constructed, the required braking force is generated as follows.

When the brake pedal 11 is depressed, M / C1
2 produces pressure. At the same time, the deceleration or the required braking force to be generated by the vehicle is previously determined by the brake control ECU 10 based on the detection value of the pedal effort sensor 14 which is the brake operation amount detecting means or the detection value (pedal stroke) of a pedal displacement sensor (not shown). It is calculated by reading from the set map.

At the beginning of the braking operation, each linear valve 16,
17 and 20 are not energized, and W / C 18 has M / C
The pressure generated by 12 is transmitted as it is.

On the other hand, the regenerative control ECU 26 uses the energy generated by the motor-generator 27 during deceleration of the vehicle, which can be recovered according to the remaining amount of the battery (not shown) so as to recover the energy. The regenerative braking force is generated in the wheels 19 by collecting the battery from the generator 27 and charging the battery.

The pressure generated by the M / C 12 is regulated by the duty ratio control by the brake control ECU 10 so that the pressure generated by the M / C 12 becomes a value obtained by subtracting the regenerative braking force from the required braking force, and the W / C 18 is performed. Be transmitted to.

As described above, by operating the brake pedal, the braking force, which is the sum of the regenerative braking force and the hydraulic braking by the M / C 12, acts on the wheels 19 to decelerate and stop the vehicle.

W / C by ABS control during brake operation
When reducing the pressure of 18, or when reducing the W / C pressure by correcting the required braking force when the later-described braking margin becomes small, the pressure increase control valve 17 is shut off to reduce the pressure. This is performed by communicating the control valve 20 or adjusting the pressure to a required W / C pressure and letting the hydraulic pressure of the W / C 18 escape to the reservoir 21.

Further, while the W / C pressure is being reduced, the motor 23
With the pump 22 driven by, it is possible to return from the reservoir 21 to the M / C 12 via the linear adjustment valve 16 in the communicating state.

Next, the correction control flow of the required braking force of the first embodiment will be described with reference to FIG. It should be noted that this control flow is executed by a program stored in advance in the brake control ECU 10.

When the depression of the brake pedal 11 starts, the required braking force is calculated as described above in step S100. The process of step S100 corresponds to a required braking force calculation means.

Next, in step S110, the braking torque gradient with respect to the slip speed is calculated. This braking torque gradient is based on the time-series data of the wheel speed from the wheel speed sensor 25 based on the slip speed which is the difference between the vehicle body speed and the wheel speed, for example, by the method described in Japanese Patent Laid-Open No. 10-114263. It is calculated by applying the parameter identification method to the recurrence formula derived from the equation of motion of. The process of step S110 corresponds to a braking margin calculation means.

The calculated braking torque gradient η corresponds to the gradient in the slip speed-braking torque diagram shown in FIG. 3, and when the braking torque gradient η is positive (regions A and B in FIG. 3), the wheels are When the vehicle is gripping on the road surface, when the braking torque gradient is 0 (point C in FIG. 3), the friction coefficient between the wheel and the road surface is the maximum value (peak μ), and the braking torque gradient is negative. At this time (region D in FIG. 3), the dynamic state of the wheel movement changes in accordance with the braking torque gradient η, such as the state where the wheel reaches the lock state. Therefore, by calculating the magnitude of the braking torque gradient η, it is possible to grasp the momentarily changing frictional state between the wheel and the road surface, and further the braking margin, which is the margin until the wheel is locked.

Next, in step S120, it is determined whether the calculated braking torque gradient η is less than or equal to a predetermined threshold value KA. If the determination result is YES, the braking torque is in the regions B to D in FIG. 3, and the braking torque gradient η is relatively small, or is negative, so that there is little margin before the wheels are locked, or the wheels are locked. As an example, in step S130, the required braking force, more specifically, the second braking force, that is, the W / C pressure, is corrected to be reduced. On the other hand, if the determination result in step S120 is NO, the braking torque is in the region A in FIG. 3, the braking torque gradient η is large, and the margin is large until the wheels are locked, so the required braking force is not corrected. This routine ends.

Now, with reference to FIG. 4 showing a state in which the braking force generated on the wheels 19 changes with time, the reduction correction of the required braking force in step S130 will be described. The reduction correction amount of the required braking force is predetermined so as to reduce only the required W / C pressure, for example, based on the magnitude of the regenerative braking force that is the first braking force and the braking torque gradient η. It can be calculated from the map. This gives η
As shown in FIG. 4B when ≦ KA, the decrease amount of the required braking force is set to be equal to the decrease amount of the hydraulic braking force of the second braking force. In other words, it can be said that the reduction correction of the required braking force is a reduction correction particularly for the second braking force and a reduction correction for the difference between the required braking force and the first braking force. The reduction correction amount may be calculated by multiplying the required braking force calculated in step S100 by a constant ratio k (<1).

The processing of step S130 corresponds to the required braking force correction means.

The operation of the brake control device according to the first embodiment performed by the above control flow will be described.

When the brake pedal 1 is depressed, the wheels 19 are placed in the non-driving state, that is, the braking state.
Braking energy due to the rotational force of the wheels 19 is generated in the motor generator 27, and the braking energy as its electrical energy is collected in a battery (not shown), so that the wheels 19 generate regenerative braking force as the first braking force. To do.

At the same time, the flow shown in FIG. 2 is executed by the program to calculate the required braking force. Figure 4
When the normal required braking force that is not corrected as shown in (a) exceeds the actually generated regenerative braking force, M / C
In 12, the M / C with the depression of the brake pedal 11
The discharge pressure of 12 increases and the linear adjustment valve 16 in the communicating state,
The pressure of the W / C 18 increases via the pressure increase control valve 17 as an N / O valve, and a second braking force by the hydraulic brake is generated on the wheels 19. In this way, by the driver's brake operation, the wheel 19 is provided with a braking force corresponding to the required braking force, which is the sum of the regenerative braking force that is the first braking force and the hydraulic braking force that is the second braking force. Can be generated.

By the way, when the braking torque gradient η calculated during the brake control becomes equal to or less than a predetermined threshold value KA, the required braking force is k times (k <(k <
Since it is reduced to 1), the braking pressure of the hydraulic brake, which is the second braking force generating means, is reduced by the following operation of the brake control device 1.

In FIG. 1, in order to reduce the pressure of the W / C 18, the pressure reducing control valve 20 is communicated with the reservoir 21 to absorb the excess W / C pressure. Further, the motor 23 is rotationally controlled to drive the pump 22 so that the brake fluid is supplied from the reservoir 21 to the M / C via the damper 24 and the linear adjustment valve 16.
Return to 12. The pressure reducing control valve 20 and the motor 23
Is the brake control EC based on the reduction correction value of the required braking force.
It is controlled by the command value from U10.

As described above, the first embodiment is provided with the regenerative braking device which is the first control force generating means and the hydraulic braking device which is the second control force generating means like the hybrid vehicle. In the brake control device, depending on the magnitude of the braking torque gradient that reflects the frictional state between the wheel and the road surface calculated based on the wheel speed, when the braking torque gradient becomes small, the margin to the wheel lock state is small. As a matter of fact, the required braking force determined according to the brake operation is reduced, and the generation control of the second braking force generation means is performed without reducing the first braking force so as to obtain the reduced corrected required braking force. Power can be reduced. Therefore, even if the frictional state between the wheel and the road surface changes, the locked state (slip state) of the wheel is prevented in advance to prevent the unstable behavior of the vehicle body, and the braking force is generated on the wheel. be able to.

Further, since the regenerative braking force which is the first braking force is not reduced, the regenerative efficiency of regenerative energy can be maintained to the maximum.

Further, in the description of the first embodiment described above, A
Although the relation with the BS controller is not specified, A
Even in a vehicle equipped with a BS control device, the required braking force correction of the first embodiment and the ABS control device can be operated without interference. That is, the brake control device of the first embodiment avoids the unstable behavior of the vehicle by reducing the required braking force in advance before the wheel lock (slip) state is set, in other words, before the ABS control operation is performed. Therefore, even in a vehicle equipped with an ABS device, by using the brake control device of the first embodiment, it is possible to prevent an excessive ABS operation in generating a necessary braking force. .

(Second Embodiment) Next, the present invention is an assist brake system vehicle equipped with a main hydraulic brake device which is a first braking force generating means and an auxiliary hydraulic brake device which is a second braking force generating means. The second embodiment applied to will be described.

FIG. 5 is a diagram showing the construction of a hydraulic circuit for two wheels of the brake control system of the second embodiment, the first circuit described above.
The same components as those in the embodiment are designated by the same reference numerals and the description thereof will be omitted. That is, the second embodiment does not include the motor generator 27 and the regenerative control ECU 26 that drive or regeneratively brake the wheels as in the first embodiment. The control logic of the brake control ECU 10 is also different from that of the first embodiment, as will be described later. Other configurations are the same for both.

In the second embodiment thus constructed, the required braking force is generated as follows.

When the brake pedal 11 is stepped on, pressure is generated by the M / C 12 as in the first embodiment, and at the same time, the detected value of the pedal effort sensor 14 which is the brake operation amount detecting means or the pedal displacement not shown. Brake control ECU based on sensor detection value (pedal stroke)
The deceleration or the required braking force that the vehicle should generate by 10 is calculated by reading from a preset map.

At the beginning of the braking operation, each linear valve 16,
17 and 20 are not energized, and W / C 18 has M / C
The pressure generated by 12 is transmitted as it is as the first braking force. When the required braking force exceeds the first braking force, the motor 23 drives the pump 22 in order to compensate for the excess braking force, that is, the shortage of the required braking force of the M / C pressure generated by the brake operation. Then, the reservoir 21
Brake fluid is pumped out further and W is supplied via the pressure increase control valve 17.
/ C18 to increase the W / C pressure to generate an assist pressure which is a second braking force.

At this time, the pressure reducing control valve 20 is in the closed state, but the linear adjusting valve 16 may be in the closed state so that the discharge pressure of the pump 22 is directly applied to the W / C 18, or the necessary assist pressure is generated. For this reason, the discharge pressure of the pump 22 may be further adjusted by adjusting the pressure of the linear adjustment valve 16. If the brake fluid stored in the reservoir 21 is insufficient during pressurization by the pump 22, the M / C 12
Brake fluid is sucked out from the reservoir 21 by W /
Added to C pressure.

When the required braking force is corrected and the W / C pressure is reduced when the braking margin, which will be described later, becomes small, the drive of the motor 23 is adjusted to 70% of the pull power by controlling the duty ratio. This is done by lowering the number of rotations and thereby lowering the discharge pressure of the pump 22.

W / C by ABS control during brake operation
When reducing the pressure of 18, the pressure increase control valve 17 is shut off, the pressure reduction control valve 20 is communicated, or the pressure is adjusted to a required W / C pressure, and the hydraulic pressure of W / C 18 is released to the reservoir 21. By doing.

Further, while the W / C pressure is being reduced, the motor 23
With the pump 22 driven by, it is possible to return from the reservoir 21 to the M / C 12 via the linear adjustment valve 16 in the communicating state.

Next, the correction control flow of the required braking force of the second embodiment will be described with reference to FIG. Note that this control flow is executed by a program stored in advance in the brake control ECU 10 as in the control flow of the above-described first embodiment, and the same processing as that of the first embodiment will be assigned the same reference numerals and will be described. Omit it.

The processing of steps S100 to S120 is the same as in the first embodiment.

Next, in step S120, if the result of the determination as to whether the calculated braking torque gradient η is less than or equal to a predetermined threshold value KA is YES, the braking torque is in the areas B to D in FIG. As the torque gradient η is relatively small or negative, it is assumed that there is little margin before the wheels are locked, or that the wheels are in the locked state, step S1.
Move to 40. On the other hand, if the determination result in step S120 is NO, the braking torque is in the region A in FIG. 3, the braking torque gradient η is large, and the margin is large until the wheels are locked, so the required braking force is not corrected. This routine ends.

In step S140, the required braking force is corrected to decrease, more specifically, the second braking force, that is, the assist pressure is corrected to be decreased. That is, the reduction correction amount of the required braking force in step S140 is predetermined so as to reduce only the assist pressure which is the second braking force, for example, based on the magnitude of the required braking force and the braking torque gradient η. It can be calculated by a map. As a result, FIG.
As shown in (b), the reduction amount of the required braking force is set to be equal to the reduction amount of the hydraulic braking force of the second braking force.
The reduction correction amount may be calculated by multiplying the required braking force calculated in step S100 by a constant ratio k (<1).

The operation of the brake control device according to the second embodiment performed by the above control flow will be described. Note that FIG. 7 shows how the braking force generated on the wheels 19 changes with time.

When the brake pedal 11 is depressed, M
/ C12 discharge pressure increases, and linear adjustment valve 1 in open state
6. W / C1 via the pressure increase control valve 17 as N / O valve
The pressure of 8 increases, and the wheel 19 generates the first braking force by the main hydraulic brake.

At the same time, the flow shown in FIG. 6 is executed by the program to calculate the required braking force. Figure 7
As shown in (a), when the required braking force exceeds the first braking force generated, the assist control is started. By the pump 22 driven by the motor 23, the M / C 12
The brake fluid is sucked from the reservoir 21 and the damper 2
4 and the pressure increase control valve 17 to discharge to the W / C 18,
As the W / C pressure increases, the assist pressure as the second braking force is added. At this time, the energization amount to the linear adjustment valve 16 and the discharge pressure of the pump 22 are controlled according to the required braking force that exceeds the first braking force. As a result, the pressure generated by the pump 22 is adjusted to the linear adjustment valve 1
Release to M / C12 side by 6 and necessary W /
Generate C pressure.

Further, when the assist pressure is corrected to be reduced in step S140, the motor 23 is adjusted according to the reduced pressure amount.
By controlling the rotation speed of the pump to decrease the discharge pressure of the pump 22, as shown in FIG.
The pressure is adjusted to a lower assist pressure as compared with the case without correction.

As described above, in the second embodiment, the first
In the assist brake system having the main hydraulic brake as the braking force generating means and the auxiliary hydraulic brake as the second braking force generating means, the braking torque reflecting the friction state between the wheel and the road surface calculated based on the wheel speed. Depending on the magnitude of the gradient, it is assumed that the margin to reach the wheel lock state is small when the braking torque gradient becomes small, and the required braking force determined according to the brake operation is reduced.
It is possible to reduce the braking force generated by the second braking force generating means without reducing the first braking force so as to obtain the reduction-corrected required braking force. Therefore, the wheels-
Even if the frictional state between road surfaces changes, the locked state (slip state) of the wheels can be prevented in advance to prevent unstable behavior of the vehicle body, and the braking force can be generated on the wheels.

Further, when the braking allowance is small (the braking torque gradient is small), the pump flow rate is lowered and the discharge pressure is lowered as compared with the assist control in which the normal required braking force is exerted as described above. The generated noise can be reduced, and at the same time energy loss can be prevented.

Further, since the required braking force is reduced in advance before the wheel is locked (slip), it is necessary to use the brake control device of the second embodiment even in a vehicle equipped with an ABS device. In generating the braking force, it is possible to prevent an excessive ABS operation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a hydraulic circuit according to a first embodiment.

FIG. 2 is a diagram showing a braking force correction control flow of the first embodiment.

FIG. 3 is a characteristic diagram of braking torque with respect to slip speed.

FIG. 4 is a time chart of the braking force generated in the first embodiment.

FIG. 5 is a diagram showing a configuration of a hydraulic circuit according to a second embodiment.

FIG. 6 is a diagram showing a braking force correction control flow of the second embodiment.

FIG. 7 is a time chart of braking force generated in the second embodiment.

[Explanation of symbols]

1 ... Brake control device, 10 ... Brake control ECU, 1
DESCRIPTION OF SYMBOLS 1 ... Brake pedal, 12 ... M / C, 13 ... Master reservoir, 14 ... Pedal force sensor, 15 ... Pressure sensor, 16 ... Linear adjustment valve, 17 ... Pressure increasing control valve, 18 ... W / C, 19 ...
Wheels, 20 ... Pressure reducing control valve, 21 ... Reservoir, 22 ... Pump, 23 ... Motor, 24 ... Damper, 25 ... Wheel speed sensor, 26 ... Regenerative control ECU, 27 ... Motor generator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mamoru Sawada             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Masaki Ooka             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Katsuhiro Asano             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Eiichi Ono             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Yuji Muragishi             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. F term (reference) 3D046 BB23 BB28 CC02 CC06 HH02                       HH16 HH36 HH52 JJ06 JJ14                       JJ19                 5H115 PA10 PG04 QE10 QI04 QI07                       QI15 QI18 QI22 SE04 TO02                       TU10

Claims (7)

[Claims] 1. A brake control device for generating a braking force between a wheel and a road surface by a driver's brake operation, and a brake operation amount detecting means for detecting a brake operation amount related to the driver's brake operation, and the detected brake. A required braking force calculation means for calculating a required braking force as a braking force to be generated based on an operation amount; a first braking force generation means for generating a first braking force on a wheel by the brake operation; and the brake operation. A second braking force generating means for generating a second braking force on the wheel by adding the second braking force to the first braking force, a wheel speed sensor for detecting a wheel speed, and a wheel speed sensor based on the detected wheel speed. A braking margin calculation means for calculating a braking torque gradient with respect to a slip speed, and a required braking force correction means for correcting the required braking force based on the braking torque gradient. When having a second braking force generating means brake control apparatus characterized by generating said second braking force based on the requested braking force which is the correction. 2. The brake control device according to claim 1, wherein the required braking force correction means reduces the required braking force when the braking torque gradient becomes equal to or less than a predetermined value. 3. The brake control according to claim 1, wherein the required braking force correction means corrects the difference between the calculated required braking force and the first braking force. apparatus. 4. The brake control device according to claim 1, wherein the required braking force correction means corrects the calculated required braking force corresponding to the second braking force. . 5. The second braking force generating means is an auxiliary hydraulic braking means for applying the second braking force to wheel rotation by applying hydraulic pressure to a wheel cylinder of the wheel by the brake operation. Claim 1 characterized by
The brake control device according to any one of items 1 to 4. 6. The first braking force generating means is a regenerative braking means that is driven by rotation of the wheels to convert the rotational force into electric energy to apply the first braking force to the wheel rotation. The brake control device according to claim 5, wherein: 7. The first braking force generating means is a hydraulic braking means that applies the first braking force to wheel rotation by applying hydraulic pressure to a wheel cylinder of the wheel by the brake operation. The brake control device according to claim 5.