JP2000223312A - Braking force controlling equipment of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable application of a braking force, without being affected by vibration of a vehicle which is caused by the state of a road surface or the like, by setting a target braking force to the vehicle is accordance with a detected signal which is outputted via a filter which eliminates the high-frequency components of a brake operation detecting signal. SOLUTION: A braking force corresponding to operation of a brake pedal BP is applied from a power hydropressure source PS, a flowing current to a pressure increasing solenoid valve SIfl or the like is duty-controlled. Shift to antiskid control is made during brake operation, and it is judged that wheels are liable to be locked. A wheel cylinder Wfr is interconnected with a reservoir RS via a pressure decreasing solenoid valve SDfr. Brake liquid in the wheel cylinder flows out into the reserver, pressure is reduced, and braking force control is performed independently for each wheel. Duty target current of each solenoid valve is corrected on the basis of operated control target current and actual flowing current, and filter level is set corresponding to the road surface adjusting result which is obtained by a wheel speed signal, when control condition is set according to the state of a road surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force control device for a vehicle, and more particularly to a braking force control device for applying a current to a braking force applying means in response to a braking operation by a driver to apply a braking force to the vehicle. Related.

[0002]

2. Description of the Related Art There is known a braking force control device configured to apply a current to a braking force applying means in response to a braking operation by a driver to apply a braking force to a vehicle. For example, Japanese Patent No. 2704772 discloses a problem that the braking oil pressure fluctuates in accordance with a change in the amount of applied electricity due to the vehicle body vibration, and the braking oil pressure acting on the brake device fluctuates unnecessarily. A brake hydraulic pressure control method has been proposed in which a change in the applied hydraulic quantity is not made to follow a change in the brake hydraulic pressure. In such a method, when the amount of braking operation is equal to or greater than a predetermined value and the amount of reduction is equal to or less than the predetermined amount of reduction, the amount of applied electricity is kept constant. That is, the amount of electricity can be reduced.

[0003]

A method for applying a braking force to a vehicle by applying an electric current to a braking force applying means having, for example, a linear solenoid, including the method described in the above publication, is called a brake-by-wire method. Therefore, various devices are known. However, according to the method described in the above publication, when the vibration generated in the traveling vehicle due to the road surface condition or the like is excessive, the driver's intention is not related to the braking operation amount such as the driver's pedaling force or the brake pedal stroke. An extraneous vibration component is added, and there is a possibility that the braking force on the vehicle will fluctuate. Alternatively, even if the driver intends to hold the brake pedal, the pedaling force or stroke may gradually decrease or increase, and the braking force may fluctuate.

Accordingly, the present invention provides a braking force control device for a vehicle which applies a current to a braking force applying means in response to a braking operation by a driver to apply a braking force to the vehicle. It is an object of the present invention to provide a braking force control device that can appropriately apply a braking force according to a braking operation of a driver without being affected.

[0005]

According to a first aspect of the present invention, there is provided a vehicle braking force control apparatus for detecting a braking operation by a driver of a vehicle. Means, target braking force setting means for setting a target braking force on the vehicle according to the detection output of the braking operation detecting means, and braking force application for applying a current and applying a braking force to the vehicle according to the amount of current supplied. And a braking force control unit for controlling the braking force application unit to apply a braking force corresponding to the target braking force set by the target braking force setting unit to the vehicle. And a filter means for removing a high-frequency component of a detection output signal of the braking operation detecting means, and the target braking force setting means is provided in accordance with a detection output signal of the braking operation detecting means output via the filtering means. There are those configured to set the target braking force for the vehicle.

Alternatively, a braking operation detecting means for detecting a braking operation by a driver of the vehicle, and a target for setting a target braking force on the vehicle in accordance with a detection output of the braking operation detecting means. Braking force setting means, braking force applying means for applying a current and applying a braking force to the vehicle in accordance with the amount of energizing current, and braking force corresponding to the target braking force set by the target braking force setting means to the vehicle A braking force control device for controlling the braking force application device so as to apply the braking force to the target. The target braking force setting device sets the target braking force according to a detection output of the braking operation detection device. Filter means for removing a high-frequency component of the braking force, wherein the braking force applying means applies to the vehicle a braking force corresponding to the target braking force output through the filtering means. Good.

According to a third aspect of the present invention, the characteristic of the filter means is at least one of a speed of the braking operation, an amount of the braking operation, and a direction of the braking operation by the driver of the vehicle detected by the braking operation detecting means. It is good to make it variable according to one. Specifically, when the speed of the braking operation by the driver is high, it means that the degree of urgency is high. Therefore, the cutoff frequency may be set higher than when the speed of the braking operation is low. When the amount of braking operation by the driver is large, it is easy to cause an unintended decrease in the amount of operation of the driver because the amount of braking operation is resisted. Therefore, when the braking operation amount is large, the cutoff frequency may be set lower than when the braking operation amount is small. When the direction of the braking operation by the driver is on the depressed side, the operation is a request for braking, so it is necessary to increase the braking force without delay. In addition, when the direction of the braking operation is on the return side, it is desirable from the feeling that there is an appropriate response delay. For this reason,
When the direction of the braking operation is on the stepping side, the cutoff frequency may be set higher than on the returning side. The braking operation amount may be a pedaling force on the brake pedal or a stroke of the brake pedal.

Further, according to a fourth aspect of the present invention, the vehicle further comprises a vibration detecting means for detecting a vibration state of the vehicle.
The characteristic of the filter means may be variable according to the vibration state detected by the vibration detection means. Specifically, when the vibration of the vehicle is large, the unintended operation amount of the driver greatly fluctuates. Therefore, when the vehicle vibration is large, the cutoff frequency may be set lower than when the vehicle vibration is small.
Further, the characteristic of the filter means may be controlled so as to change according to the vehicle speed of the vehicle. Specifically, when the vehicle speed is high, the behavior of the vehicle is easily changed by the braking operation, and the operation of the brake pedal by the driver is also easily changed. Therefore, when the vehicle speed is high, the cutoff frequency may be set lower than when the vehicle speed is low.

According to another aspect of the present invention, there is provided a braking operation detecting means for detecting a braking operation by a driver of the vehicle and an operation amount of the braking operation; Target braking force setting means for setting a target braking force, braking force applying means for applying a current and applying a braking force to the vehicle in accordance with the amount of current supplied, and target braking force set by the target braking force setting means. A braking force control device for controlling the braking force application unit to apply a corresponding braking force to the vehicle, wherein the vibration detection unit detects a vibration state of the vehicle; When the fluctuation amount of the operation amount of the braking operation detected by the braking operation detection means within a predetermined time is equal to or less than a predetermined amount, the braking force holding means for holding the output of the braking force applying means is provided. May be configured to increase the predetermined amount as detected vibration level is greater vibration detecting means.

The vibration detecting means may include a wheel speed detecting means for detecting a wheel speed, and may be configured to detect a vibration state of the vehicle based on the wheel speed detected by the wheel speed detecting means. Alternatively, a vehicle height detecting means for detecting a height (vehicle height) of the vehicle from the road surface is provided, and the vibration state of the vehicle is detected based on the vehicle height detected by the vehicle height detecting means. Can also.

[0011]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a vehicle braking force control apparatus according to the present invention. In accordance with an operation of a brake pedal BP, each wheel FL,
Wheel cylinders Wfl, Wfr, Wr for FR, RL, RR
The power hydraulic pressure is supplied to l and Wrr. These wheel cylinders Wfl and the like are connected to a power hydraulic pressure source PS via a pressure increasing solenoid valve SIfl and the like. Further, the wheel cylinder Wfl and the like are connected to a reservoir RS of a master cylinder MC described later via a pressure reducing solenoid valve SDfl and the like. The wheel FL indicates the front left wheel as viewed from the driver's seat, the wheel FR indicates the front right wheel, the wheel RL indicates the rear left wheel, and the wheel RR indicates the rear right wheel.

The power hydraulic pressure source PS includes a hydraulic pump HP and an accumulator AC. The hydraulic pump HP is driven by an electric motor (not shown), and introduces brake fluid from the suction side to increase the pressure to a predetermined pressure. The output is output from the discharge side, and the accumulator AC is configured to accumulate the discharge brake hydraulic pressure of the hydraulic pump HP.

In this embodiment, all the pressure increasing solenoid valves SIfl, SIfr, SIrl, SIrr and the front wheel side pressure reducing solenoid valves SDfl, SDfr are normally closed linear solenoid valves, and the rear wheel side pressure reducing solenoid valve SDrl. , SDrr are normally open linear solenoid valves. Further, the wheel cylinders Wfr, Wfl of the front wheels FR, FL are connected to the master cylinder MC via solenoid valves SE1, SE2. These solenoid valves SE1 and SE2 are always at the positions shown in FIG. 1, and function as so-called cutoff valves when the power hydraulic pressure source PS is normal. In the master cylinder MC, when the power hydraulic pressure source PS fails, the solenoid valve SE1 and the like are set to the open position, and the brake fluid in the reservoir RS is boosted in response to the operation of the brake pedal BP, so that the wheels FL, The master cylinder hydraulic pressure is output to the brake hydraulic system of the FR.

The master cylinder MC of this embodiment is a tandem-type master cylinder having two pressure chambers C1 and C2. The pressure chamber C1 is connected to the wheel cylinder Wfr of the wheel FR, and the pressure chamber C2 is a wheel of the wheel FL. It is connected to the cylinder Wfl. That is, as shown in FIG.
Pistons PN1, PN2, and PN3 are slidably accommodated in the cylinder CR, and pressure chambers C1 and C2 and a liquid chamber C3 are defined. Each chamber has a compression spring S1 and a compression spring S1, respectively.
2 and S3 are accommodated. Each room C1, C2, C3,
When the brake pedal BP is not operated, it is connected to the reservoir RS. However, when the pistons PN1, PN2, PN3 move forward in response to the operation of the brake pedal BP, the reservoir R is opened.
The communication with S is configured to be cut off.

The piston PN in the master cylinder MC
3, the spring S3 and the liquid chamber C3 constitute a pedal stroke simulator SM. Since the master cylinder MC does not operate when the power hydraulic pressure source PS is normal as described later, the spring C3 corresponds to the operating force applied to the brake pedal BP. This is to secure a stroke having a size as large as possible. The liquid chamber C3 is connected to a reservoir RS via a normally closed solenoid valve SC.

The pressure increasing solenoid valve SIfl and the like, the pressure reducing solenoid valve SDfl and the like, and the motor (not shown) of the hydraulic pump HP are connected to an electronic control unit ECU.
The drive is controlled by the electronic control unit ECU. FIG.
The members indicated by P are pressure sensors, which are also connected to the electronic control unit ECU. Although not shown, an operation force sensor for detecting an operation force applied to the brake pedal BP and a stroke sensor for detecting a stroke of the brake pedal BP are provided.
U is connected. Thus, in the electronic control unit ECU, the target hydraulic pressure of the wheel cylinder hydraulic pressure of each wheel cylinder Wfl and the like is calculated, and the pressure increasing solenoid valve SIfl and the like and the pressure reducing solenoid valve SDfl and the like are adjusted to match the target hydraulic pressure. Opening / closing is controlled.

Further, each wheel is provided with a wheel speed sensor (not shown), which is connected to the electronic control unit ECU. The rotation speed of each wheel, that is, a pulse having a pulse number proportional to the wheel speed, is provided. The signal is configured to be input to the electronic control unit ECU. When the power hydraulic pressure source PS is normal and the wheels tend to lock during braking, for example, the electronic control unit ECU controls the opening and closing of the pressure-intensifying solenoid valve SIfl and the pressure-reducing solenoid valve SDfl and the like. Skid control is performed.

Although not shown, the electronic control unit ECU includes a microcomputer including a processing unit (CPU), memories (ROM, RAM), input ports, output ports, and the like, which are interconnected via a bus. The memory (ROM) stores programs for various processes including the flowcharts shown in FIGS. 2 to 6, and the processing unit (CPU) executes the programs while an ignition switch (not shown) is closed. , A memory (RAM) temporarily stores variable data necessary for executing the program.

The operation of the embodiment having the above configuration will be described. When the brake pedal BP is operated while the power hydraulic pressure source PS is normal, the solenoid valve S is operated.
E1 and SE2 are excited to the closed position, and the pressure reducing solenoid valves SDrl and SDrr are excited to the closed position. Thereafter, the current supplied to the pressure-intensifying solenoid valve SIfl and the like is duty-controlled so that the braking force corresponding to the operation of the brake pedal BP is applied from the power hydraulic pressure source PS. In this case, after the communication between each chamber of the master cylinder MC and the reservoir RS is cut off, the piston PN1
However, since the solenoid valve SC is excited to be in the open position, the liquid chamber C3 communicates with the reservoir RS, and the piston PN3 moves forward against the urging force of the spring S3. Becomes Thus, a stroke corresponding to the applied operating force is secured on the brake pedal BP.

For example, when the control is shifted to the anti-skid control during the braking operation, and it is determined that the wheel FR has a tendency to lock, for example, the solenoid valve SE1 is kept in the closed position, and the pressure-intensifying solenoid valve SIfr is closed. At the same time, the pressure reducing solenoid valve SDfr is set to the open position. Thus, the wheel cylinder Wfr is connected to the pressure reducing solenoid valve S.
The brake fluid in the wheel cylinder Wfr flows into the reservoir RS and is reduced in pressure by communicating with the reservoir RS via Dfr. Thus, independent braking force control is performed for each wheel.

When the power hydraulic pressure source PS fails, the solenoid valves SC, SE1, SE2, the pressure increasing solenoid valve SIfl, etc., and the pressure reducing solenoid valve SDfl, etc. are de-energized and returned to the state shown in FIG. When the brake pedal BP is operated in this state, the liquid chamber C3 of the master cylinder MC is operated.
After the communication between the piston PN and the reservoir RS is interrupted,
3 cannot be advanced, but the solenoid valves SE1, SE1,
Since SE2 is in the open position, the pistons PN1 and PN2
Moves forward in response to the operation of the brake pedal BP, and the master cylinder hydraulic pressure is supplied from the pressure chambers C1 and C2 of the master cylinder MC to the wheel cylinders Wfr and Wfl via the solenoid valves SE1 and SE2, respectively.

When the brake pedal BP is not operated,
The solenoid valves SC, SE1, SE2, the pressure increasing solenoid valve SIfl, etc., and the pressure reducing solenoid valve SDfl, etc. are de-energized to the state shown in FIG.
Since N1 to PN3 return to the initial position, each chamber of the master cylinder MC communicates with the reservoir RS. Therefore, the brake fluid pressure is not supplied to the wheel cylinder Wfl or the like from either the power fluid pressure source PS or the master cylinder MC.

In the present embodiment configured as described above, a series of processing such as braking force control is performed by the electronic control unit ECU, and an ignition switch (not shown) is used.
Is closed, the execution of the program corresponding to the flowcharts of FIGS. 2 to 6 and the like starts. FIG. 2 shows the control of the linear solenoid valves such as the pressure increasing solenoid valve SIfl and the pressure reducing solenoid valve SDfl. First, at step 101, the electronic control unit ECU is initialized. Next, in step 102, the process waits until a predetermined time (for example, 7 ms) elapses. That is, in the present embodiment, the following processing is performed in a cycle of 7 ms, but is not particularly limited to this time.

In step 103, the stroke and the pedaling force indicating the operation amount of the brake pedal BP, the state of the brake switch (not shown), the energizing current, the vehicle body acceleration, the wheel cylinder hydraulic pressure (Pwc), and the accumulator hydraulic pressure (P
For ac) and the like, various processes required for control are performed.
In step 104, a duty-target current map (not shown) of each solenoid valve is corrected based on the calculated control target current and the actual energizing current.

Next, the routine proceeds to step 105, where step 1
The target wheel cylinder hydraulic pressure is calculated based on the stroke and the pedaling force of the brake pedal BP input at 03. Feedback control is performed based on the relationship between the target wheel cylinder fluid pressure and the actual wheel cylinder fluid pressure to correct the target wheel cylinder fluid pressure. Thereafter, the corrected target wheel cylinder fluid pressure is referred to as the target wheel cylinder fluid pressure. Call.

In step 106, a comparison is made between the target wheel cylinder hydraulic pressure and the actual wheel cylinder hydraulic pressure obtained in step 105, and any one of pressure increase, hold, and pressure reduction is performed according to the comparison result. The pressure mode is set. When the actual wheel cylinder fluid pressure is smaller than the target wheel cylinder fluid pressure, the target current and duty of the pressure-intensifying solenoid valve SIfl and the like are set to the values in the pressure-increasing mode in step 107, and
At 8, the target current and the duty of the pressure reducing solenoid valve SDfl and the like are also set to the values in the pressure increasing mode. In particular,
A target current is set based on a target wheel cylinder hydraulic pressure-target current map (not shown) representing solenoid valve characteristics, and a duty corresponding to the target current is set based on a target current-duty map (not shown). You. In the holding mode of steps 109 and 110, and step 1
The same processing is performed in the decompression mode of 11, 112.

The above process is repeated until the process is completed for all the wheels. If it is determined in step 113 that the process is completed, the process proceeds to step 114, where the target current and the duty are output. Thus, the wheel cylinder pressure is controlled according to the brake operation input of the vehicle driver. In the present embodiment, the wheel cylinder hydraulic pressure is used as the control target, but the same processing can be performed by using the longitudinal acceleration of the vehicle.

FIG. 3 shows an example of the calculation process of the target wheel cylinder hydraulic pressure performed in step 105 of FIG. First, in step 201, the filter level F
L is cleared (0). This filter level FL is
The higher the value, the lower the cutoff frequency. Then, the process proceeds to a step 202, wherein the brake pedal B
The target wheel cylinder hydraulic pressure Pwb before the filtering process is calculated according to the braking operation amount such as the pedaling force and stroke of P.

Next, at step 203, the road surface condition is determined, and the filter level FL is set according to the road surface condition. It should be noted that the determination of the road surface state is such that the more the road surface is rough, the greater the vehicle vibration. Therefore, the road surface determination result (for example, the vehicle (The coefficient of friction of the traveling road surface). If the road is good, the process proceeds to step 204, and the filter level FL is kept as it is. If the road is bad, the filter level FL is counted up by one in step 205. The level FL is counted up by two.

Subsequently, in step 207, the operation state of the brake pedal BP is determined. If the driver is depressing the brake pedal BP, step 208 is executed.
The filter level FL is kept as it is, and if the operation is on the return side, the filter level FL is incremented by 1 in step 209.

Further, proceeding to step 210, step 2
The hydraulic pressure gradient of the target wheel cylinder hydraulic pressure Pwb before the filtering process calculated in 02 is obtained, and the urgency of pressure increase or pressure reduction is determined based on the absolute value thereof. If the hydraulic pressure gradient of the target wheel cylinder hydraulic pressure Pwb is large, step 211 is executed.
, The filter level FL is kept as it is. If the filter level is medium, the filter level FL is counted up by 1 in step 212, and if it is smaller, the filter level FL is counted up by 2 in step 213.

At step 214, the filter level FL is determined. When the filter level FL is 0 based on the determination result, the cutoff frequency is set to f1 at step 215, and when the filter level FL is 1, In step 216, the cutoff frequency becomes f
When the filter level FL is 2, the cutoff frequency is set to f3 in step 217, and when the filter level FL is 3, the cutoff frequency is set to f4 in step 218. When the filter level FL is 4 or more, the cutoff frequency is set to f5 in step 219.

The cutoff frequencies f1 to f5 have a relationship of f1>f2>f3>f4> f5, and the cutoff frequency increases as the numerical value of the filter level FL decreases, and the cutoff frequency decreases as the numerical value increases. It is set as follows. Incidentally, as these cutoff frequencies f1 to f5, for example, a 1/4 filter, a 1/16 filter,
The moving average of the past four to 128 times of data may be obtained by using the / 32 filter, the 1/64 filter, and the 1/128 filter, respectively. Filter processing is performed in this manner, and in step 220, the target wheel cylinder hydraulic pressure Pwf is set.

FIG. 4 shows an example of the input processing performed in step 103 of FIG. 2 according to another embodiment of the present invention. First, in step 301, the stroke and depression force of the brake pedal BP, the state of a brake switch (not shown), the energizing current, the vehicle body acceleration, the wheel cylinder fluid pressure (Pwc), the accumulator fluid pressure (Pac), and the like are read into a memory. In step 302, the filter level FL is cleared (0).

Next, at step 303, the road surface condition is determined based on the road surface determination result (for example, the friction coefficient of the road surface on which the vehicle is running) determined when the anti-skid control condition is set, as in the above-described embodiment. The filter level FL is set according to the road surface condition. That is, if the road is good, the process proceeds to step 304, and the filter level FL is kept as it is. If the road is bad, the filter level FL is counted up by one in step 305. Is counted up by 2.

Subsequently, the operation state of the brake pedal BP is determined in step 307, and if the driver is depressing the brake pedal BP, step 308 is performed.
The filter level FL is kept as it is, and if the operation is on the return side, the filter level FL is incremented by 1 in step 309.

Further, the routine proceeds to step 310, where the change rate (gradient) of the stroke of the brake pedal BP is determined. If the change rate of the stroke is equal to or more than the predetermined rate and it is determined that the brake pedal operation is fast, step 311
In step 312, the filter level FL is counted up by 1 in step 312, and if the brake pedal operation is slow, the filter level FL is counted up in step 313 in step 313. . It should be noted that also in step 310, the braking operation may be determined based on the gradient of the wheel cylinder hydraulic pressure as in step 210.

At step 314, the filter level FL is determined. When the filter level FL is 0 according to the determination result, the cutoff frequency is set to f1 at step 315, and the filter level FL is 1. Sometimes, in step 316, the cutoff frequency becomes f
When the filter level FL is 2, the cutoff frequency is set to f3 in step 317, and when the filter level FL is 3, the cutoff frequency is set to f4 in step 318. When the filter level FL is 4 or more, the cutoff frequency is set to f5 in step 319. These cutoff frequencies f1 to f5 are also f1>f2> f similarly to the above-described embodiment.
3>f4> f5, and the cutoff frequency is set to be higher as the numerical value of the filter level FL is smaller, and to be lower as the numerical value is larger.

The filter processing is performed as described above, and at step 320, the operation amount of the brake pedal BP (for example, the stroke after filtering) is set. Instead of the stroke of the brake pedal BP, the brake pedal BP
May be used to represent the operation amount of the brake pedal BP. The pedaling force applied to the brake pedal BP can be detected by the master cylinder hydraulic pressure.

FIGS. 5 to 8 relate to still another embodiment of the present invention, and the flowcharts of FIGS.
Another example of the calculation process of the target wheel cylinder hydraulic pressure performed in step 103 of FIG. First, based on the road surface determination result obtained when setting the anti-skid control condition based on the wheel speed signal, steps 401 and 4 are performed.
03, a road surface condition is determined, and a hysteresis width A, which is a fluctuation width of the operation amount of the braking operation, is determined according to the road surface condition.
Is set. That is, if it is determined in step 401 that the road is extremely rough, the process proceeds to step 402, and the hysteresis width A is set to A2. If the road is not extremely rough, it is further determined in step 403 whether or not the road is rough. If it is determined that the road is bad, the process proceeds to step 404, and the hysteresis width A is set to A1, and if the road is good, the process proceeds to step 405, where the hysteresis width A is A.
It is set to 0. In this case, there is a relationship of A2>A1> A0, and as shown in FIG. 7, the hysteresis width A is set to increase as the road surface condition deteriorates. The bad road determination may be made based on the number of vibrations and the amplitude of the wheel acceleration per unit time.

Next, at step 406, it is determined whether or not the previous time is outside the hysteresis range based on the state of a hysteresis flag or a non-hysteresis flag described later.
If it is outside the hysteresis range, the process proceeds to step 407 and thereafter. If it is within the hysteresis range, step 417 in FIG.
Proceed to the following. In step 407, it is determined whether or not the brake pedal input has increased from the previous time. If the brake pedal input has increased or is maintained, the process proceeds to step 408, where the target wheel cylinder hydraulic pressure is increased to the basic pressure increasing target hydraulic pressure shown in FIG. After the setting, the process returns to the main routine.

If it is determined in step 407 that the brake pedal input has decreased from the previous time, step 4
At 09, the hysteresis range is set. That is, it is set to a range between the value of the previous target wheel cylinder fluid pressure and a value obtained by subtracting the hysteresis width A from the value. Then, the routine proceeds to step 410, where it is determined whether or not the brake pedal input is within the hysteresis range. If the brake pedal input is within the hysteresis range, the hysteresis-in-progress flag is set (1) at step 411, and then the routine proceeds to step 412. The wheel cylinder pressure is set to the same value as the previous target wheel cylinder pressure, and the wheel cylinder pressure is maintained.

If it is determined in step 410 that the brake pedal input is out of the hysteresis range, the out-of-hysteresis flag is set (1) in step 413, and the process proceeds to step 414, where the target wheel cylinder fluid pressure Predetermined value X from target wheel cylinder fluid pressure
Is set to the value obtained by subtracting. This is because if there is a large difference between the basic pressure-reducing side target hydraulic pressure corresponding to the brake pedal input and the previous target wheel cylinder hydraulic pressure, so-called pressure drop occurs, the difference is reduced to prevent this. Things. The basic pressure-reducing-side target hydraulic pressure is a characteristic at the time of pressure reduction when the hysteresis width is the hysteresis width A0 on a good road, and is set as shown in FIG.

The target wheel cylinder hydraulic pressure set in the above step 414 is compared with a basic pressure reducing side target hydraulic pressure corresponding to a brake pedal input in a step 415. If the target wheel cylinder hydraulic pressure is lower than the target hydraulic pressure, the process proceeds to a step 416. The wheel cylinder hydraulic pressure is set to the same value as the basic reduced pressure side target hydraulic pressure. If the target wheel cylinder hydraulic pressure is equal to or higher than the basic pressure reducing target hydraulic pressure, the process returns to the main routine.

On the other hand, if it is determined in step 406 that the previous time is within the hysteresis range, step 417 in FIG.
It is determined whether or not the brake pedal input has increased from the previous time.
It is determined whether or not the brake pedal input is outside the hysteresis range, and if it is within the hysteresis range, the routine proceeds to step 419, where the target wheel cylinder fluid pressure is set to the same value as the previous target wheel cylinder fluid pressure. After that, the process returns to the main routine. If it is determined in step 418 that the brake pedal input is out of the hysteresis range, the out-of-hysteresis flag is set (1) in step 420, and then the process proceeds to step 421, where the target wheel cylinder fluid pressure corresponds to the brake pedal input. Is set to the basic pressure increase side target hydraulic pressure.

If it is determined in step 417 that the brake pedal input has decreased from the previous time, it is determined in step 422 whether the brake pedal input is within the hysteresis range. If the brake pedal input is within the hysteresis range, the process proceeds to step 419. After the target wheel cylinder fluid pressure is set to the same value as the previous target wheel cylinder fluid pressure, the process returns to the main routine. If it is determined in step 422 that the brake pedal input is outside the hysteresis range, the out-of-hysteresis flag is set (1) in step 423, and then the process proceeds to step 424, where the target wheel cylinder hydraulic pressure is set as the target wheel cylinder hydraulic pressure. It is set to a value obtained by subtracting a predetermined value X from the hydraulic pressure. This target wheel cylinder hydraulic pressure is compared with the basic pressure-reducing side target hydraulic pressure corresponding to the brake pedal input in step 425,
If it is lower than this, the routine proceeds to step 426, where the target wheel cylinder hydraulic pressure is set to the basic pressure reducing side target hydraulic pressure.
If the target wheel cylinder hydraulic pressure is equal to or higher than the basic pressure reducing target hydraulic pressure, the process returns to the main routine.

According to the present embodiment, the hysteresis width can be set larger on a rough road where the vehicle is vibrated violently than on a good road where the vibration is small. It can be reliably prevented.
In the present embodiment, when setting the control conditions of the anti-skid, for example, the road surface state is determined based on the friction coefficient of the vehicle traveling road surface obtained based on the wheel speed, but is not limited to this. Alternatively, the road condition may be determined based on, for example, the number of vibrations and the amplitude of a vehicle height sensor (not shown) in a unit time. Also.
The hysteresis width is not a fixed value, but may be variable according to the vehicle speed or brake pedal input.

[0048]

The present invention has the following effects because it is configured as described above. That is, the vehicle braking force control apparatus of the present invention includes a filter means for removing a high-frequency component of a detection output signal of the braking operation detecting means, as described in claim 1, and outputs the signal via the filter means. A target braking force for the vehicle set according to a detection output signal of the braking operation detecting means.
The filter means for removing the high-frequency component of the target braking force according to the detection output of the braking operation detection means as described in,
It is configured to apply a braking force corresponding to the target braking force output through the filter means to the vehicle, so that the braking force can be appropriately adjusted according to the braking operation of the driver without being affected by the vibration of the vehicle. A braking force can be applied.

Then, the characteristics of the filter means are set according to claim 3.
Alternatively, if variable as described in claim 4, appropriate filter characteristics can be set according to various operating conditions.

Further, when the variation of the operation amount of the braking operation during a predetermined time is equal to or less than a predetermined amount, the output of the braking force applying means is held, and the larger the vibration level of the vehicle is, the more the braking force is applied. Even when configured to increase the predetermined amount, without being affected by the vibration of the vehicle,
Appropriate braking force can be applied according to the driver's braking operation.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of a vehicle braking force control device according to the present invention.

FIG. 2 is a flowchart showing the entire braking force control according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating an example of a calculation process of a target wheel cylinder hydraulic pressure according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating an example of an input process according to another embodiment of the present invention.

FIG. 5 is a flowchart illustrating an example of a calculation process of a target wheel cylinder hydraulic pressure according to another embodiment of the present invention.

FIG. 6 is a flowchart illustrating an example of a calculation process of a target wheel cylinder hydraulic pressure according to another embodiment of the present invention.

FIG. 7 is a graph showing a map for setting a hysteresis width according to a road surface condition in another embodiment of the present invention.

FIG. 8 is a graph showing a relationship between a brake pedal input and a target wheel cylinder hydraulic pressure in another embodiment of the present invention.

[Explanation of symbols]

BP brake pedal, MC master cylinder, H
P Hydraulic pump RS Reservoir, Wfr, Wfl, Wrr, Wrl Wheel cylinder FR, FL, RR, RL Wheel ECU Electronic control unit

Claims (5)

[Claims] 1. A braking operation detecting means for detecting a braking operation by a driver of a vehicle, a target braking force setting means for setting a target braking force on the vehicle in accordance with a detection output of the braking operation detecting means, and a current supply. Braking force applying means for applying a braking force to the vehicle in accordance with the amount of current supplied; and applying the braking force so as to apply to the vehicle a braking force corresponding to the target braking force set by the target braking force setting means. A braking force control device for a vehicle, comprising: a braking force control means for controlling the means.
Filter means for removing a high-frequency component of a detection output signal of the braking operation detection means, wherein the target braking force setting means is configured to output the target braking force according to the detection output signal of the braking operation detection means output through the filter means. A braking force control device for a vehicle, wherein a target braking force is set for the vehicle. 2. A braking operation detecting means for detecting a braking operation by a driver of a vehicle, a target braking force setting means for setting a target braking force on the vehicle in accordance with a detection output of the braking operation detecting means, and a current supply. Braking force applying means for applying a braking force to the vehicle in accordance with the amount of current supplied; and applying the braking force so as to apply to the vehicle a braking force corresponding to the target braking force set by the target braking force setting means. A braking force control device for a vehicle, comprising: a braking force control means for controlling the means.
Filter means for removing a high-frequency component of the target braking force set by the target braking force setting means in accordance with the detection output of the braking operation detection means; and a filter corresponding to the target braking force output via the filter means. A braking force control device for a vehicle, wherein the braking force applying means applies the power to the vehicle. 3. A characteristic of the filter means is variable according to at least one of a speed of a braking operation, a braking operation amount, and a direction of the braking operation by the driver of the vehicle detected by the braking operation detecting means. The vehicle braking force control device according to claim 1 or 2, wherein 4. The apparatus according to claim 1, further comprising vibration detecting means for detecting a vibration state of said vehicle, wherein characteristics of said filter means are made variable according to the vibration state detected by said vibration detecting means. 4. The braking force control device for a vehicle according to claim 2 or 3. 5. A braking operation detecting means for detecting a braking operation by the driver of the vehicle and an operation amount of the braking operation, and a target braking force for setting a target braking force on the vehicle in accordance with a detection output of the braking operation detecting means. Setting means, a braking force applying means for applying a current and applying a braking force to the vehicle according to the amount of the supplied current, and applying a braking force corresponding to the target braking force set by the target braking force setting means to the vehicle. A braking force control unit that controls the braking force application unit so as to control the vibration state of the vehicle, and the braking operation detected by the braking operation detection unit. A braking force holding unit that holds an output of the braking force applying unit when a variation width of the operation amount of the operation during a predetermined time is equal to or less than a predetermined amount, wherein the larger the detected vibration level of the vibration detecting unit is, A vehicle braking force control device configured to increase the predetermined amount.