JP2002152904A - Braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation of an anti-lock braking device by a regenerative brake without causing 'sense of sudden fall of G' while making effective use of the regenerative brake as much as possible, in the braking device for vehicle, capable of using both frictional braking and regenerative braking. SOLUTION: This brake device includes a motor 1, capable of generating the driving force of a vehicle and regenerative braking force at deceleration and braking, and is structured the frictional braking with a mechanical brake 4 and the regenerative braking through the motor 1 can be used in combination, and a control means 7, when an operation start detecting means 7A detects the operation start of anti-lock brake control, stops the regenerative braking force corresponding to brake pedal operating amount and takes only the regenerative braking force, corresponding to engine brake based on detection information from the operation start detecting means 7A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle braking device which can use both frictional braking using a mechanical braking device and regenerative braking through an electric motor that generates driving force for the vehicle.

[0002]

2. Description of the Related Art In general, in an electric vehicle, a frictional braking force by a mechanical braking device (mechanical brake) for applying a frictional force to wheels by a fluid pressure such as hydraulic pressure or air pressure to perform braking,
Braking can be performed by a regenerative braking force of a regenerative braking device that causes a motor (generator) that generates a driving force of a vehicle to function as a generator and applies the generated load to wheels (drive wheels) to perform braking.

[0003] Some braking devices that can apply a friction braking force and a regenerative braking force are further provided with a function of executing antilock brake control (ABS control) for preventing locking of wheels. However, while the ABS control is performed for each wheel, the regenerative braking generally controls all the drive wheels in the same manner, so that the ABS control and the regenerative braking control are not the same. Then, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 89, the regenerative braking force is set to 0 when the ABS is activated.

Japanese Patent Application Laid-Open No. 2000-50409 discloses that regenerative braking is stopped during braking under predetermined conditions and braking is performed only by frictional braking force so that the turning performance of the vehicle does not deteriorate during braking. Techniques are also disclosed.

[0005]

By the way, in order to utilize the regenerative brake more effectively, it is sufficient to apply a braking force to the brake operation amount (brake pedal depression amount) as shown in FIG. That is, if the accelerator pedal is not depressed, even if the brake operation amount is 0, the braking force equivalent to the engine brake is applied by the regenerative brake, and if the brake operation amount is applied, the braking force equivalent to the engine brake is reduced to this braking operation amount. Apply the appropriate braking force. At this time, the braking force to be applied is first given by the regenerative brake, and when the regenerative braking force becomes insufficient, the friction braking force by the mechanical brake is applied to the maximum regenerative brake.

However, if the regenerative braking force is reduced to 0 during the operation of the ABS as described above, all of the braking force according to the brake operation amount can be dealt with by applying a mechanical brake. Since the regenerative braking force equivalent to the engine brake as shown in the figure becomes zero, the braking force is suddenly released, so-called "G missing feeling".
Will occur.

For example, if the road surface on which the vehicle runs is a low μ road, and the road surface μ is, for example, 0.25, the wheel slips and the ABS operates when the deceleration due to the brake operation exceeds 0.25 G. At first, the deceleration is suppressed to 0.25G. As the deceleration reaches 0.25G, the ABS
It is assumed that the regenerative braking force is given by 0.15 G immediately before the start of the effect, and 0.1 G of the regenerative braking force is the regenerative braking force equivalent to the engine brake. Here, when the ABS starts to work, the regenerative braking force 0.1 G equivalent to the engine brake suddenly disappears at the same time, so that the deceleration is from 0.25 G to 0.15 G (= 0.25 G-0. 1
G), and the "G missing feeling" occurs.

[0008] JP-A-2000-62590 discloses that A
If the regenerative braking force is reduced to zero during the execution of the BS control, the total braking force decreases, and it becomes impossible to secure a sufficient braking force. In view of the fact that the locking tendency is eliminated due to the decrease in the braking force applied to the vehicle and the ABS control cannot be continuously performed, even if the regenerative braking force is reduced during the execution of the ABS control, There has been proposed a braking force control device that prevents a decrease in braking performance due to a decrease in braking force and enables the execution state of the ABS control to be maintained.
However, in this technology, the regenerative braking force is basically set to 0 in order to prevent the performance of the ABS control from deteriorating, and the disappearance of the regenerative braking force is compensated for by the friction braking force by the mechanical brake. It cannot be said that it is used for

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and uses a regenerative brake as effectively as possible.
It is an object of the present invention to provide a braking device for a vehicle that can prevent a decrease in anti-lock brake control due to a regenerative brake without causing a “G-miss feeling” that lowers a brake feeling.

[0010]

Therefore, the vehicle braking device according to the first aspect of the present invention includes an electric motor capable of generating a driving force for the vehicle and also generating a regenerative braking force during deceleration and braking. , Friction braking using a mechanical braking device,
Regenerative braking through the electric motor can be used in combination, and when the operation start detecting means detects the start of the operation of the antilock brake control, the control means performs a brake pedal operation based on the detection information from the operation start detecting means. The regenerative braking force corresponding to the operation amount is stopped, and only the regenerative braking force corresponding to the engine brake is used. Thereby, while preventing regenerative braking from interfering with the antilock brake control, a braking force equivalent to the engine brake can be secured, and the occurrence of the "G feeling of missing" can be prevented.

According to a second aspect of the present invention, there is provided a vehicle braking device including an electric motor that generates a driving force for the vehicle and can also generate a regenerative braking force during deceleration and braking. Braking and regenerative braking through the electric motor can be used together, and when the operation start detecting means detects the start of the operation of the antilock brake control, the control means performs the operation based on the detection information from the operation start detecting means. ,
The regenerative braking force corresponding to the operation amount of the brake pedal is stopped, and only the regenerative braking force corresponding to the engine brake is used. In this case, if the wheel slip rate detected by the slip rate detecting means is equal to or greater than a predetermined value, the control means controls to stop or reduce the regenerative braking force corresponding to the engine brake. Thereby, while preventing regenerative braking from interfering with the antilock brake control, a braking force equivalent to the engine brake can be secured, and the occurrence of the "G feeling of missing" can be prevented.

In this case, the vehicle further comprises a road surface μ detecting means for detecting or estimating a road surface μ of a road surface on which the vehicle travels, and the control means comprises a control means for detecting a wheel slip rate from the slip rate detecting means when the wheel slip rate is equal to or more than a predetermined value. It is preferable that the regenerative braking force is controlled based on the detection information from the road surface μ detecting means so that the regenerative braking force has a magnitude corresponding to the road surface μ (claim 3).

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a vehicle braking device according to an embodiment of the present invention; FIG. FIG. 2 is a flowchart illustrating the details of the braking control. As shown in FIG. 1, this braking device is provided in an electric vehicle that travels by driving and driving drive wheels (front wheels in this example) 2 and 2 by an electric motor (motor) 1. And a mechanical braking device (mechanical brake) 4 for mechanically applying frictional braking force so that the vehicle is braked by the regenerative braking force and the frictional braking force. Has become.

The regenerative brake 3 comprises the motor 1 and the motor controller 5. When the driver releases the accelerator operation (depressing the accelerator pedal 11), this information is sent to the motor controller 5 via the accelerator position sensor 21 and the like. The motor controller 5 controls the motor 1 to function as a generator so that the power generation load of the motor 1 as the generator is applied to the driving wheels 2 and 2 to exert a braking force equivalent to an engine brake. Has become.

Further, the mechanical brake 4 has a master cylinder (M) which operates in response to the depression of the brake pedal 12.
/ C) 13, wheel cylinders (not shown) provided for the wheels 2, 2, 6, and 6, and fluid pressure (here, hydraulic pressure but air pressure) from the master cylinder 13 is applied to each wheel cylinder. A brake actuator 15 which is interposed in a fluid pressure circuit 14 for supplying the fluid pressure and adjusts and outputs the fluid pressure, and a brake provided on each of the wheels 2, 2, 6, and 6 and driven by a wheel cylinder to contact a brake disc 16 Pad 17 is provided.

When the driver performs a braking operation (depressing the brake pedal 12), a braking force corresponding to the braking operation amount is applied in addition to the braking force equivalent to the engine brake. , 2 are provided with a braking force corresponding to the engine brake and a braking force corresponding to the braking operation amount, and the driven wheels (rear wheels in this example) 6, 6 are subjected to the braking operation. An appropriate braking force is applied.

In this case, as for the braking force applied to the driven wheels 6, 6, the friction braking force using the mechanical brake 4 is used, but the braking force corresponding to the amount of braking operation applied to the driving wheels 2, 2 is used. As shown in FIG. 3, the regenerative braking force is applied as much as possible, and when the regenerative braking force alone cannot be satisfied, the friction braking force by the mechanical brake 4 is added to the regenerative braking force.

As described above, in order to coordinate the regenerative braking force and the friction braking force, the braking device uses the braking operation amount (the depression amount of the brake pedal 12) detected by the hydraulic pressure sensor 22.
A brake controller (control means) 7 which outputs control signals to the motor controller 5 and the brake actuator 15 based on the brake fluid pressure (fluid pressure) corresponding to the above and integrates and controls them.

The brake controller 7 outputs a control signal to the brake actuator 15 so that all braking forces corresponding to the braking operation amount are applied to the driven wheels 6 and 6 by the friction braking force of the mechanical brake 4 during the braking operation. I do. Alternatively, if all can be compensated by the regenerative braking force of the driving wheels, a control signal is output to the brake actuator 15 so that the friction braking force by the mechanical brake 4 is not applied to the driven wheels 6, 6. Until the regenerative braking force reaches the maximum limit, all the braking forces according to the braking operation amount are applied to the drive wheels 2 and 2 by the regenerative braking force by the regenerative brake 3, and when the regenerative braking force reaches the maximum limit. A control signal is output to the motor controller 5 and the brake actuator 15 so that a braking force corresponding to a braking operation amount is given by the maximum regenerative braking force by the regenerative brake 3 and the friction braking force by the mechanical brake 4.

Incidentally, an anti-lock brake device (ABS) 8 is attached to this braking device in order to prevent the brake wheels from being locked when traveling on a low μ road. The ABS 8 determines whether the locking tendency of the wheels 2 and 6 is determined based on one of the wheel speed sensors 23 provided for the wheels 2, 2, 6 and 6, respectively.
The brake actuator 15 individually reduces the braking force of the wheels that tend to lock, and prevents the locking of the braking wheels.

The motor 1 simultaneously applies a driving force and a regenerative braking force to the left and right driving wheels 2 and 2,
In BS8, since the braking forces of the wheels 2, 2, 6, and 6 are individually controlled, regenerative braking and ABS are controls that are hardly compatible with each other. As described above, the regenerative braking force includes a braking force corresponding to the engine brake and a braking force corresponding to the brake operation amount. In the ABS, the braking force corresponding to the brake operation amount is reduced for each wheel. Of the regenerative braking force, the braking force corresponding to the brake operation amount interferes with the ABS. However, the braking force equivalent to the engine brake is basically A
Does not interfere with BS. That is, in an automobile whose driving wheels are driven by an engine (internal combustion engine), the engine brake operates even during the ABS control. Therefore, based on such an automobile, a braking force equivalent to the engine brake is basically provided. A
It does not affect BS.

Therefore, in the brake controller 7 of this braking device, when the ABS is operated during the braking operation, basically, the application of the braking force corresponding to the brake operation amount out of the regenerative braking force is stopped, and the engine brake equivalent is stopped. Only the braking force is given. In this case, the braking force corresponding to the brake operation amount in the regenerative braking force disappears, but this is appropriately compensated for by the mechanical brake. The brake controller 7 includes an operation start determination unit (operation start detection unit) 7A for determining the start of the operation of the ABS. Based on this, the operation of the ABS is started.

Further, when the ABS is operated, an extremely low μ road where the tendency of locking the wheel does not fall even if only the regenerative braking force equivalent to the engine brake is applied is conceivable. And stop applying regenerative braking force equivalent to engine brake,
Alternatively, the regenerative braking force corresponding to the engine brake is reduced.

More specifically, when the slip ratio λ of the wheel reaches a predetermined value a during the ABS operation, the application of the regenerative braking force equivalent to the engine brake is stopped in order to secure the performance of the ABS (ie, , Stop all regenerative braking force)
When the slip ratio λ of the wheel does not reach the predetermined value a, the road surface μ is determined or estimated, and the regenerative braking force equivalent to the engine brake does not exceed the braking force corresponding to the road surface μ (that is, the slip of the wheel is reduced). Control so that it can be suppressed).

The slip ratio λ is calculated by the slip ratio calculating means 24 from the vehicle speed Xv and the wheel speed Xw by, for example, the following equation. The predetermined value a is set to a value (for example, about 20 to 40%) larger than the slip ratio λ (for example, about 10%) at which the operation of the ABS is assumed to start. λ = (Xv−Xw) / Xv Further, the wheel speed Xw is detected by the wheel speed sensor 23,
The vehicle speed Xv is estimated based on the wheel speed Xw detected by the wheel speed sensor 23. For example, if there is no slip on the wheels, the wheel speed Xw matches the vehicle speed Xv.
Therefore, the largest value among the four wheel speeds Xw of the four wheels may be adopted. Here, it is assumed that an abnormally large maximum value is output due to a disturbance or the like. Without using the maximum value, each wheel speed X of the four wheels
The second largest value of w is adopted. Further, when slippage occurs in each wheel, it may be estimated as a value obtained by adding a time integral value of the longitudinal acceleration of the vehicle thereafter to the vehicle speed Xv immediately before the occurrence of slippage.

The road surface μ (road surface friction coefficient μ) is calculated by the road surface μ calculating means 25 by a known method. Conventionally, various methods have been employed for calculating (estimating) the road surface μ, examples of which are disclosed in, for example, JP-A-60-35646 and JP-A-3-128755. All of these road surface μ estimation methods focus on the fact that the wheel deceleration is proportional to the road surface μ during braking, and calculate and obtain the road surface μ based on the wheel deceleration of the target wheel. Here, as the target wheel, among the wheel speeds of the respective wheels, for example, the wheel having the second highest wheel speed is uniquely selected. Japanese Patent Application Laid-Open No. 7-40826 discloses an average front wheel speed of both front wheels and a selected rear wheel speed selected based on the principle of select high. A method of estimating a road surface μ in which one of these wheel speeds is selected by determining a height relationship with the speed and a road surface μ is calculated based on a differential value of the selected wheel speed is disclosed. The road surface μ calculating means 25 calculates the road surface μ by using these techniques.

The braking force according to the road surface μ is a magnitude at which the longitudinal acceleration of the vehicle becomes a value corresponding to the road surface μ (ie, μG). By controlling the braking force, it is possible to control so that the regenerative braking force equivalent to the engine brake does not exceed the braking force according to the road surface μ. Since the vehicle braking device as one embodiment of the present invention is configured as described above, regenerative braking is controlled, for example, as shown in FIG.

That is, first, it is determined whether or not a braking operation is being performed (during operation of a brake pedal) (step S10). If a braking operation is being performed, the process proceeds to step S20 to determine whether or not regenerative braking control is being performed. Here, if the regenerative brake control is not being performed, only the mechanical brake is performed and the regenerative brake is not performed (step S90). If the regenerative brake is being performed, it is determined whether the ABS is operating (step S30).

If the ABS operation is not being performed, normal regenerative braking control is performed (step S80). That is, the sum of the braking force corresponding to the engine brake and the braking force corresponding to the braking operation amount is applied to the drive wheels 2 and 2 using the regenerative braking force as much as possible. If the braking force according to the braking operation amount is not sufficient with the regenerative braking force alone, the braking force is supplemented by the friction braking force using the mechanical brake 4.

On the other hand, if the ABS is operating, step S4
The process proceeds to 0, the application of the braking force corresponding to the braking operation amount out of the regenerative braking force is stopped, only the braking force corresponding to the engine brake is applied, and the ABS is performed by controlling the friction braking force using the mechanical brake 4. Therefore, even if the ABS is activated,
A braking force equivalent to the engine brake by the regenerative braking force is secured, so that it is possible to prevent the occurrence of the “G feeling of missing” and improve the braking feeling. In addition, the regenerative braking force is used as effectively as possible.

Next, it is determined whether or not the wheel slip ratio λ has reached a predetermined value a (step S5).
0). When the slip ratio λ reaches the predetermined value a, step S
Proceeding to 100, the application of the regenerative braking force equivalent to the engine brake is also stopped (that is, all the regenerative braking forces are stopped), and the braking force is given only by the ABS control using the mechanical brake.
The predetermined value a is set to a value that is sufficiently larger than a value at which the operation of the ABS is expected. When such a large slip ratio occurs, the slip of the wheels is generated by applying a regenerative braking force equivalent to the engine brake. (Lock when braking), so stop all regenerative braking force immediately,
Wheel grip (i.e., lock suppression) can be entrusted to ABS control.

On the other hand, if the wheel slip ratio λ does not reach the predetermined value a, the road surface μ is determined or estimated (step S).
60), control is performed so that the regenerative braking force equivalent to the engine brake does not exceed the braking force corresponding to the road surface μ (step S7).
0). As a result, the regenerative braking force equivalent to the engine brake is applied within a range that does not cause the wheel to slip (here, lock), and the wheel is slipped (locked) while using the regenerative braking as much as possible. By suppressing the interference, interference with the ABS can be avoided.

That is, it is possible to more reliably avoid the regenerative braking from interfering with the antilock brake control while more effectively utilizing the regenerative braking force. Note that the above-described embodiment is an example for describing the present invention, and the embodiment can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, when the slip ratio λ of the wheel does not reach the predetermined value a, the regenerative braking force corresponding to the engine brake is controlled so as not to exceed the braking force according to the road surface μ. If the predetermined value a is set to be relatively small, if the slip ratio λ of the wheel does not reach the predetermined value a, it may be set so as to apply only the regenerative braking force equivalent to the engine brake as in step S40. Thereby, control is further simplified.

Step S50 and subsequent steps in FIG. 2 are deleted, and during the ABS operation, the application of the braking force corresponding to the braking operation amount of the regenerative braking force is stopped, and only the braking force equivalent to the engine brake is applied. May be set as follows. Thereby, the control is further simplified.

[0035]

As described in detail above, according to the vehicle brake system of the present invention, when the antilock brake control is started, the regenerative braking force corresponding to the brake pedal operation amount is stopped. Since only the regenerative braking force equivalent to the engine brake is used, it is possible to secure the braking force equivalent to the engine brake while preventing the regenerative braking from interfering with the anti-lock brake control, thereby preventing the occurrence of the "G feeling missing". it can. Thereby, the braking feeling can be improved. In addition, the regenerative braking force is used as effectively as possible, and the effective use of energy is promoted.

According to the second aspect of the present invention, when the antilock brake control is started, the regenerative braking force corresponding to the operation amount of the brake pedal is stopped, and the regenerative braking force corresponding to the engine brake is stopped. Only, and further, when the wheel slip rate is equal to or more than a predetermined value, the regenerative braking force equivalent to the engine brake is stopped or reduced, so that
While reliably preventing the regenerative braking from interfering with the anti-lock brake control, a braking force equivalent to the engine brake can be secured and the occurrence of the "G feeling of missing" can be prevented.
Thereby, the braking feeling can be improved. In addition, the regenerative braking force is used as effectively as possible, and the effective use of energy is promoted.

According to the third aspect of the present invention, when the wheel slip ratio is equal to or more than a predetermined value, the regenerative braking force is controlled so as to have a magnitude corresponding to the road surface μ. Thus, it is possible to more reliably avoid the regenerative braking from interfering with the anti-lock brake control while more effectively utilizing the regenerative braking force.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a vehicle braking device as one embodiment of the present invention.

FIG. 2 is a flowchart illustrating the details of braking control by a vehicle braking device as one embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating conventional regenerative cooperative control.

[Explanation of symbols]

 Reference Signs List 1 electric motor (motor) 3 regenerative braking device (regenerative brake) 4 mechanical braking device (mechanical brake) 7 brake controller (control means) 7A operation start determination means (operation start detection means) 8 antilock brake device (ABS) 24 slip Rate calculation means 25 Road μ calculation means

Continued on the front page F term (reference) 3D046 BB23 BB28 CC02 EE01 EE03 HH02 HH16 HH36 HH46 LL02 LL05 LL21 5H115 PA01 PA08 PG04 PU01 QE10 QE14 QE15 QI04 QI07 QI12 QI14 SE04 TB01 TO23 TO26 TW07

Claims (3)

[Claims] An electric motor which generates a driving force of a vehicle, and which can also generate a regenerative braking force during deceleration and braking, is provided.
In a vehicle braking device that can use both friction braking using a mechanical braking device and regenerative braking through the electric motor, an operation start detecting unit that detects an operation start of antilock brake control; and Control means for stopping the regenerative braking force corresponding to the operation amount of the brake pedal and using only the regenerative braking force equivalent to the engine brake when the anti-lock brake control starts operating based on the detection information of A braking device for a vehicle, characterized in that: 2. An electric motor which generates a driving force of a vehicle, and which can also generate a regenerative braking force during deceleration and braking.
In a vehicle braking device that can use both friction braking using a mechanical braking device and regenerative braking through the electric motor, an operation start detecting unit that detects an operation start of antilock brake control, and a vehicle wheel slip ratio. When the anti-lock brake control starts operating based on the detected slip ratio detecting means and the detection information from the operation start detecting means, the regenerative braking force corresponding to the brake pedal operation amount is stopped and the engine brake is stopped. Control means for controlling only the regenerative braking force corresponding to only the substantial regenerative braking force and stopping or reducing the regenerative braking force corresponding to the engine brake when the wheel slip rate from the slip rate detecting means is a predetermined value or more. A braking device for a vehicle, comprising: 3. The vehicle according to claim 1, further comprising: a road surface μ detecting unit for detecting or estimating a road surface μ of a road surface on which the vehicle travels, wherein the control unit detects a wheel slip ratio from the slip ratio detecting unit that is equal to or more than a predetermined value. 3. The vehicle braking device according to claim 2, wherein the regenerative braking force is controlled so as to have a magnitude corresponding to the road surface μ based on detection information from the road surface μ detecting means.