JPH11301434A - Brake force control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and adequately control a brake force according to brake requirement from a driver. SOLUTION: A target deceleration Gst is calculated based on a pushing stroke Sp of a brake pedal (S20), a target deceleration Gpt is calculated based on a master cylinder pressure Pm (S30), a weight α for the target deceleration Gpt is calculated based on a final target deceleration Gt calculated at previous time (S40), a final target deceleration Gt is calculated as a weighting sum of the target deceleration Gpt and the target deceleration Gst (S50), a target wheel cylinder pressure Pti for each wheel is calculated as a value proportional to the final target deceleration Gt (S60), a wheel cylinder pressure Pti for each wheel is feedback controlled so as to be the target wheel cylinder pressure Pti (S70).

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, and more particularly to a braking force control device.

[0002]

2. Description of the Related Art As one of braking force control devices for a vehicle such as an automobile, a target deceleration of a vehicle based on a master cylinder pressure and a change in the master cylinder pressure is disclosed in, for example, JP-A-9-30394. Is calculated, and a braking force control device that controls the braking force so that the deceleration becomes the target deceleration is conventionally known.

According to such a braking force control device, the braking force is controlled in accordance with both the master cylinder pressure and the change in the master cylinder pressure. Is higher, the braking force is higher, so that the target deceleration is calculated based on only the master cylinder pressure,
The braking force can be appropriately controlled according to the driver's braking request.

[0004]

Generally, there is a relationship as shown in FIG. 6 between the depression force on the brake pedal and the master cylinder pressure. When the depression force on the brake pedal is low, the master pressure detected by the pressure sensor is low. Since the accuracy of estimating the brake pedal depression force based on the cylinder pressure is low, the conventional braking force control device as described above controls the braking force with high accuracy according to the driver's braking request when the depression force on the brake pedal is low. Can not do it.

It is conceivable to use the depression stroke of the brake pedal as an alternative value of the master cylinder pressure. The relationship shown in FIG. 7 is between the depression force on the brake pedal and the depression stroke of the brake pedal. Yes, when the brake pedal depression stroke is large, the accuracy of estimating the pedal depression force based on the depression stroke detected by the stroke sensor is low. Therefore, when the braking force is controlled based on the brake pedal depression stroke, the brake pedal depression When the stroke is large, the braking force cannot be controlled with high accuracy in accordance with the driver's braking request.

More generally, the driver mainly controls the depressing stroke of the brake pedal in a region where the desired deceleration is low, whereas the driver mainly applies the pedaling force to the brake pedal in a region where the desired deceleration is high. When the braking force is controlled based on either the master cylinder pressure or the depression stroke of the brake pedal, it is difficult to properly control the braking force in response to the driver's braking request. .

The present invention has been made in view of the above-mentioned problems in a conventional braking force control device configured to control a braking force based on a master cylinder pressure or a depression stroke of a brake pedal. The main object of the present invention is that the accuracy of estimating the brake pedal depressing force based on the master cylinder pressure and the accuracy of estimating the brake pedal depressing force based on the depressed stroke differ depending on the driver's operation of the brake pedal, and that the driver operates with a desired deceleration. Noting that the driver's control mode is different, by considering both the master cylinder pressure and the depressing stroke of the brake pedal, the braking force can be accurately and appropriately controlled in accordance with the driver's braking request. is there.

[0008]

According to the present invention, a main object of the present invention is to detect a state quantity corresponding to a depression operation of a brake pedal by a driver,
In a vehicle braking force control device that calculates a target braking force according to a detected state amount and controls the braking force to be the target braking force, the state amount is determined by a master cylinder pressure and a depression of the brake pedal. A braking force control device for a vehicle, wherein the degree of contribution of the master cylinder pressure and the depression stroke to the target braking force is changed according to at least one of the master cylinder pressure and the depression stroke. Is done.

According to the first aspect of the present invention, the target braking force corresponding to the master cylinder pressure and the depression stroke of the brake pedal is calculated, and the master cylinder pressure for the target braking force is determined according to at least one of the master cylinder pressure and the depression stroke. Since the degree of contribution of the pressure and the depression stroke is changed, for example, by changing the degree of contribution according to the deceleration desired by the driver, the braking force can be controlled accurately and appropriately in response to the driver's braking request. It becomes possible to do.

[0010]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the target deceleration based on the master cylinder pressure and the target deceleration based on the depression stroke of the brake pedal are calculated. The target braking force is calculated based on the weighted sum of the two target decelerations, and the contribution of the master cylinder pressure and the depression stroke to the target braking force is changed by changing the weight of the two target decelerations. (Preferred embodiment 1).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the weight of the two target decelerations is changed based on one of the two target decelerations. (Preferred embodiment 2).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the weights of the two target decelerations are changed based on the previously calculated target braking force or a value corresponding thereto. (Preferred embodiment 3).

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electronic control device of one embodiment of a vehicle braking force control device according to the present invention.

In FIG. 1, reference numeral 10 denotes a hydraulic brake device. The brake device 10 has a master cylinder 14 for pumping brake oil in response to a depression operation of a brake pedal 12 by a driver. I have. Master cylinder 1
One end of a brake hydraulic control conduit 16 for the left front wheel and one end of a brake hydraulic control conduit 18 for the right front wheel are connected to 4, and the other ends of these brake hydraulic control conduits control the braking force of the left front wheel and the right front wheel, respectively. Wheel cylinders 20FL and 20FR are connected. In the middle of the brake hydraulic pressure control conduits 16 and 18, a normally-open solenoid valve 2 is provided.
2FL and 22FR are provided.

A stroke simulator 24 and a reservoir 26 are connected to the master cylinder 14, and one end of a hydraulic supply conduit 28 and a hydraulic discharge conduit 30 are connected to the reservoir 26. An oil pump 34 driven by an electric motor 32 is provided in the middle of the hydraulic supply conduit 28, and the other end of the hydraulic supply conduit 28 is connected via a hydraulic supply conduit 36FL for the left front wheel and a part of the brake hydraulic control conduit 16. To the front left wheel cylinder 20FL, and to the right front wheel cylinder 20FR via a part of the right front wheel hydraulic supply conduit 36FR and the brake hydraulic control conduit 18, to provide a left rear wheel hydraulic supply conduit 36RL. Is connected to the wheel cylinder 20RL of the left rear wheel via a part of the hydraulic supply conduit 36RL for the left rear wheel and to the wheel cylinder 20RR of the right rear wheel via the hydraulic supply conduit 36RR for the right rear wheel. I have.

Similarly, the other end of the hydraulic discharge conduit 30 is connected to a hydraulic discharge conduit 38FL for the left front wheel and a hydraulic supply conduit 36FL for the left front wheel.
And a part of the brake hydraulic control conduit 16 are connected to the wheel cylinder 20FL of the left front wheel, a hydraulic discharge conduit 38FR for the right front wheel, a hydraulic supply conduit 36FR and a brake hydraulic control conduit 18 for the right front wheel. Connected to the wheel cylinder 20FR of the right front wheel through a part of the hydraulic discharge conduit 38FL for the left front wheel, the hydraulic discharge conduit 38RL for the left rear wheel, and the hydraulic supply conduit 36RL for the left rear wheel. And a part of the hydraulic discharge conduit 38RL for the left rear wheel and the hydraulic discharge conduit 38RR for the right rear wheel.
And it is connected to the wheel cylinder 20RR of the right rear wheel via a part of the hydraulic supply conduit 36RR for the right rear wheel.

Hydraulic supply conduits 36FL, 36RL, 36RL, 3
In the middle of 6RR, each normally closed type electromagnetic flow control valve 40F
L, 40FR, 40RL, and 40RR are provided, and in the middle of the hydraulic discharge conduits 38FL, 38RL, 38RL, and 38RR, normally closed electromagnetic flow control valves 42FL, 42FR, and 42RL, respectively.
42RR is provided. The brake oil pressure control conduits 16 and 18 are provided with pressure sensors 44FL and 44FR for detecting the pressure in the corresponding control conduits as the pressures Pfl and Pfr in the wheel cylinders 20FL and 20FR, respectively. Are provided with pressure sensors 44RL and 44RR for detecting the pressures in the corresponding conduits as the pressures Prl and Prr in the wheel cylinders 20RL and 20RR.

Further, the brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke Sp of the brake pedal 12, and the master cylinder 14 and the electromagnetic opening / closing valve 22 for the right front wheel are provided.
A pressure sensor 48 for detecting the pressure in the brake hydraulic control conduit 18 between the FR and the FR as the master cylinder pressure Pm is provided. A pressure sensor 50 for detecting the pressure in the control conduit as a pump supply pressure Pp is provided in the hydraulic supply conduit 28 on the discharge side of the oil pump 34.

The electromagnetic switching valves 22FL, 22FR, the electric motor 32, and the electromagnetic flow control valves 42FL, 42FR, 42RL, 42RR are controlled by an electronic control unit 52 as described later in detail. The electronic control unit 52 includes a microcomputer 54 and a drive circuit 56, and the microcomputer 5
Although not shown in detail in FIG. 1, reference numeral 4 denotes a central processing unit (CPU) and a read only memory (ROM).
, A random access memory (RAM), and an input / output port device, which may be connected to each other by a bidirectional common bus.

In the input / output port device of the microcomputer 54, pressures Pi (i = fl, f) in the wheel cylinders 20FL to 20RR are detected by pressure sensors 44FL to 44RR, respectively.
r, rl, rr), a signal indicating the depression stroke Sp of the brake pedal 12 from the stroke sensor 46, a signal indicating the master cylinder pressure Pm from the pressure sensor 48, and a signal indicating the pump supply pressure Pp from the pressure sensor 50. It is supposed to be.

The ROM of the microcomputer 54 stores a control flow described later, and the CPU determines the target of the vehicle based on the depression stroke Sp of the brake pedal 12 and the master cylinder pressure Pm detected by the sensors described above. The deceleration is calculated, the target wheel cylinder pressure of each wheel is calculated based on the target deceleration, and control is performed so that the wheel cylinder pressure of each wheel becomes the target wheel cylinder pressure.

Next, the operation of the braking force control device according to the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started when an ignition switch (not shown) is turned on, and is repeatedly executed at predetermined time intervals. When the ignition switch is turned on, the solenoid valves 22FL and 22FR are closed prior to step 10, whereby the communication between the master cylinder 14 and the wheel cylinders 20FL and 20FR is cut off.

First, in step 10, a signal indicating the depression stroke Sp of the brake pedal 12 detected by the stroke sensor 46 is read, and in step 20, the signal corresponding to the graph shown in FIG. The target deceleration Gst based on the depression stroke Sp is calculated from the map, and in step 30, the master cylinder pressure Pm is calculated from the map corresponding to the graph shown in FIG.
Is calculated based on the target deceleration Gpt.

In step 40, the weight α (0 ≦ α ≦) for the target deceleration Gpt based on the master cylinder pressure Pm from the map corresponding to the graph shown in FIG. 5 based on the final target deceleration Gt calculated last time. 1) is calculated, and in step 50, the target deceleration G is calculated according to the following equation 1.
The final target deceleration Gt is calculated as a weighted sum of pt and the target deceleration Gst. Gt = αGpt + (1−α) Gst (1)

In step 60, the final target deceleration G
Assuming that the coefficient (positive constant) of the target wheel cylinder pressure of each wheel with respect to t is Ki (i = fl, fr, rl, rr), the target wheel cylinder pressure Pti (i) of each wheel according to the following equation (2).
= Fl, fr, rl, rr) are calculated. Pti = Ki Gt (2)

In step 70, feedback control is performed so that the wheel cylinder pressure Pi of each wheel becomes the target wheel cylinder pressure Pti. In this case, when the brake pedal 12 is not depressed by the driver and the final target deceleration Gt is 0, the oil pump 34 is not driven, and the electromagnetic on-off valves 22FL and 22FR are maintained in the closed state. Flow control valves 42FL, 42FR, 42RL, 42RR
1 is also maintained in the position of FIG. 1, so that no braking force is applied to each wheel.

On the other hand, when the brake pedal 12 is depressed by the driver, the depression stroke Sp is reduced.
Is greater than or equal to the reference value Spo, the oil pump 34 is driven by the electric motor 32 as necessary so that the pressures Pfl-Prr in the wheel cylinders 20FL-20RR of each wheel become the target wheel cylinder pressures Ptfl-Ptrr. The electromagnetic flow control valves 42FL, 42FR, 42RL, and 42RR are feedback-controlled, whereby the braking force of each wheel is controlled in accordance with the driver's depressing operation of the brake pedal 12.

Thus, according to the illustrated embodiment, at step 20, the target deceleration Gst based on the depression stroke Sp of the brake pedal 12 is calculated, and at step 3
At 0, a target deceleration Gpt based on the master cylinder pressure Pm is calculated, and at step 40, a weight α for the target deceleration Gpt is calculated based on the last calculated final target deceleration Gt, and at step 50 Target deceleration Gpt
The final target deceleration Gt is calculated as a weighted sum of the target deceleration Gst and the target wheel cylinder pressure Pti of each wheel is calculated as a value proportional to the final target deceleration Gt in step 60, and in step 70 Feedback control is performed so that the wheel cylinder pressure Pi of each wheel becomes the target wheel cylinder pressure Pti.

Therefore, according to the illustrated embodiment, the weight α for the target deceleration Gpt based on the master cylinder pressure Pm.
Is small in an area where the amount of depression of the brake pedal 12 by the driver is small, and is variably set so as to gradually increase as the amount of depression of the brake pedal 12 increases, so that the final target deceleration Gt becomes equal to the master cylinder pressure Pm or the brake pedal 12. The wheel cylinder pressure Pi of each wheel is more accurately controlled in accordance with the driver's operation of depressing the brake pedal 12 than when the operation is performed based only on the depression stroke Sp of the vehicle or when the weight α is constant. Thus, the braking force of each wheel can be controlled with high accuracy in accordance with the driver's braking request.

In particular, according to the illustrated embodiment, the target deceleration Gst based on the depression stroke Sp and the target deceleration Gpt based on the master cylinder pressure Pm are calculated, and the target deceleration Gt is calculated based on the last calculated final target deceleration Gt. The weight α for Gpt is calculated, the final target deceleration Gt is calculated as a weighted sum of the target deceleration Gpt and the target deceleration Gst, and the target wheel cylinder pressure Pti of each wheel is calculated as a value proportional to the final target deceleration Gt. Therefore, the target wheel cylinder pressure Pti of each wheel is simply calculated as compared with the case where the target wheel cylinder pressure Pti itself of each wheel is calculated based on the weighted sum of the target deceleration Gpt and the target deceleration Gst. be able to.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described embodiment, the final target deceleration Gt is calculated as a weighted sum of the target deceleration Gpt based on the master cylinder pressure Pm and the target deceleration Gst based on the depression stroke Sp. However, for example, a change rate ΔPm of the master cylinder pressure is calculated, and a target deceleration Δ based on the change rate ΔPm of the master cylinder pressure is obtained from a map set in advance based on the change rate ΔPm.
Gpt is calculated, and the final target deceleration Gt is calculated as the target deceleration Gpt.
And ΔGpt may be calculated as a weighted sum of the target deceleration Gst.

In the above embodiment, the weight α for the target deceleration Gpt is calculated based on the last calculated final target deceleration Gt. The calculation may be performed based on the deceleration Gst.

In the above embodiment, the target deceleration Gpt based on the master cylinder pressure Pm is calculated from the linear map shown in FIG. The map for the calculation may be calculated from a non-linear map as shown by a broken line in FIG.

In the above-described embodiment, the coefficients Ki for calculating the target wheel cylinder pressures Pti of the respective wheels based on the final target deceleration Gt in step 60 are constants. May be variably set in accordance with, for example, the running state or running environment of the vehicle.

In the above-described embodiment, the booster is not provided in the master cylinder 14. However, the brake device 10 may be provided with a booster in the master cylinder. Although the power supply 34 is supplied by being driven by the electric motor 32 as needed, an accumulator may be provided in the braking device 10 as shown by a virtual line in FIG.

[0038]

As is apparent from the above description, according to the first aspect of the present invention, the target braking force according to the master cylinder pressure and the depression stroke of the brake pedal is calculated, and the master cylinder pressure and the depression force are calculated. The degree of contribution of the master cylinder pressure and the depressing stroke to the target braking force is changed according to at least one of the strokes. For example, by changing the degree of contribution according to the deceleration desired by the driver, the driver's braking request is changed. Accordingly, the braking force can be controlled with high accuracy and appropriateness.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of one embodiment of a vehicle braking force control device according to the present invention.

FIG. 2 is a flowchart showing an operation of the braking force control device according to the illustrated embodiment.

FIG. 3 is a graph showing a relationship between a depression stroke Sp of a brake pedal and a target deceleration Gst.

FIG. 4 is a graph showing a relationship between a master cylinder pressure Pm and a target deceleration Gpt.

FIG. 5 is a graph showing a relationship between a final target deceleration Gt calculated last time and a weight α for the target deceleration Gpt.

FIG. 6 is a graph showing the relationship between the depression force on the brake pedal and the master cylinder pressure Pm.

FIG. 7 is a graph showing a relationship between a depression force on a brake pedal and a depression stroke Sp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Braking device 12 ... Brake pedal 14 ... Master cylinder 20FL-20RR ... Wheel cylinder 44FL-44RR ... Pressure sensor 46 ... Stroke sensor 48, 50 ... Pressure sensor 52 ... Electronic control device

Claims (1)

[Claims] 1. A vehicle for detecting a state quantity corresponding to a depression operation of a brake pedal by a driver, calculating a target braking force according to the detected state quantity, and controlling the braking force to be the target braking force. In the braking force control device, the state quantity is a master cylinder pressure and a depression stroke of the brake pedal, and the master cylinder pressure and the target braking force with respect to the target braking force according to at least one of the master cylinder pressure and the depression stroke. A braking force control device for a vehicle, wherein the degree of contribution of the depression stroke is changed.