JP2000247219A - Braking force controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the sudden change of braking force, the impairing of steering stability of the vehicle caused thereby and the physical disorder felt by a driver, by preventing the sudden change of a target deceleration in a case when the anormality is found in any one of a plurality of sensors. SOLUTION: The final target deceleration Gt is operated on the basis of the result of detection by the pressure sensors 66, 68 detecting the pressure Pm1, Pm2 of a master cylinder 14 and by a stroke sensor 70 detecting the pedalling stroke Sp of a brake pedal 12, and the braking force of each wheel is controlled on the basis of the same. When any one of sensors is changed between a normal state and an abnormal state, the deviation Δ Gt between the final target deceleration Gt operated while including the result of detection by the abnormal sensor and the final target deceleration Gt operated while excluding the result of detection by the abnormal sensor, is determined, the final target deceleration Gt is corrected on the basis of the deviation Δ Gt, and the magnitude of the deviation Δ Gt is gradually reduced.

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 controlling a braking force based on detection results of a plurality of braking operation amount detecting means.

[0002]

2. Description of the Related Art As one of braking force control devices for vehicles such as automobiles, for example, as described in Japanese Patent Application Laid-Open No. 9-30394, a master cylinder pressure is detected by a pressure sensor, and the master cylinder pressure and its change are detected. 2. Description of the Related Art A braking force control device configured to calculate a target deceleration of a vehicle based on a rate and control a braking force of each wheel based on the target deceleration is conventionally known.

[0003]

In a braking force control device which calculates a target deceleration of a vehicle based on the detection result of the sensor as described above and controls the braking force of each wheel based on the target deceleration, In order to improve the speed calculation accuracy, for example, based on the detection results of a plurality of sensors for detecting the braking operation amount of the driver, such as two pressure sensors for detecting the master cylinder pressure and a stroke sensor for detecting the depression stroke of the brake pedal. It is conceivable to calculate the target deceleration.

However, when it is detected that an abnormality has occurred in any of the plurality of sensors, the target deceleration must be calculated excluding the braking operation amount detected by the sensor in which the abnormality has occurred. Therefore, even if there is no sudden change in the amount of braking operation by the driver, the target deceleration may fluctuate abruptly at the stage when it is detected that an abnormality has occurred in the sensor, and therefore the braking force fluctuates abruptly. As a result, there is a problem that the steering stability of the vehicle is deteriorated and the driver feels strangeness.

The present invention provides a braking force control system which calculates a target deceleration based on detection results of a plurality of sensors for detecting a braking operation amount of a driver and controls a braking force of each wheel based on the target deceleration. The present invention has been made in view of the above-described problems in the apparatus, and a main object of the present invention is to prevent a sudden change in a target deceleration when any of a plurality of sensors has an abnormality. Accordingly, it is an object of the present invention to prevent a sudden change in the braking force and a deterioration in the driving stability of the vehicle or a driver from feeling uncomfortable due to the sudden change in the braking force.

[0006]

According to the present invention, a main object of the present invention is to provide a brake operation amount detecting means for detecting the amount of braking operation on a braking operation member by a driver. Abnormality detecting means for detecting an abnormality of the plurality of braking operation amount detecting means, and when no abnormality is detected by the abnormality detecting means, a vehicle operation based on the braking operation amount detected by the plurality of braking operation amount detecting means. A normal operation mode for calculating a target deceleration, and a braking operation amount detected by a braking operation amount detecting means other than the braking operation amount detecting means when the abnormality is detected by the abnormality detecting means. A target deceleration calculating means having an abnormal time calculation mode for calculating a target deceleration of the vehicle based on the target deceleration calculating mode; A target deceleration change reducing unit configured to reduce a change from a target deceleration calculated in a mode before switching to a target deceleration calculated in a mode after switching when the mode is switched between the abnormal mode and the target mode; This is achieved by a vehicle braking force control device having control means for controlling a braking device based on deceleration.

According to the first aspect of the present invention, when the operation mode of the target deceleration operation means is switched between the normal operation mode and the abnormal operation mode, the target deceleration calculated by the mode before switching is used. Since the change to the target deceleration calculated by the mode after switching is reduced by the target deceleration change reduction means, any one of the braking operation amount detection means has changed between a normal state and an abnormal state. Is detected, the target deceleration is prevented from suddenly fluctuating.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned construction, the plurality of braking operation amount detecting means may include a pressure of a master cylinder of the braking device. And a stroke sensor that detects a depression stroke of a brake pedal of the braking device (the configuration of claim 2).

According to the second aspect of the present invention, when the pressure sensor and the stroke sensor are normal, the target deceleration of the vehicle is controlled by the driver based on both the pressure of the master cylinder and the depression stroke. Accurately calculated according to the amount, and when the pressure sensor or stroke sensor is detected to have changed between a normal state and an abnormal state, the target deceleration is prevented from suddenly fluctuating. Is done.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned structure of the first or second aspect, the plurality of braking operation amount detecting means may include a master cylinder of the braking device. At least two pressure sensors for detecting the pressure of the master cylinder. In the normal operation mode, the target deceleration calculating means sets a target based on an average value of the pressure of the master cylinder detected by at least the two pressure sensors. It is configured to calculate the deceleration (the configuration of claim 3).

According to the third aspect of the present invention, when the two pressure sensors are normal, the target deceleration of the vehicle is controlled by the driver based on the average value of the master cylinder pressure detected by the two pressure sensors. The target deceleration fluctuates rapidly even when it is accurately calculated according to the amount of braking operation on the operating member, and when it is detected that any of the pressure sensors has changed between a normal state and an abnormal state. Is reliably prevented.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration according to any one of claims 1 to 3, the target deceleration change reducing means may include a mode before switching. Is configured to gradually change from the target deceleration calculated by the above to the target deceleration calculated by the mode after switching.

According to the configuration of claim 4, when the operation mode of the target deceleration operation means is switched between the normal operation mode and the abnormal operation mode, the target deceleration is calculated in the mode before the switching. Since the target deceleration is gradually changed to the target deceleration calculated in the mode after switching from the target deceleration, the target deceleration is reliably prevented from suddenly changing.

According to the present invention, in order to achieve the above-mentioned main object effectively, the target deceleration change reducing means may be arranged so that the target deceleration change reducing means is in the normal operation mode. It is configured to correct the target deceleration calculated by the mode after the switching by the correction amount corresponding to the deviation between the target deceleration calculated before and after the switching between the mode and the abnormality calculation mode. (Configuration of Claim 5).

According to the fifth aspect of the present invention, when the operation mode of the target deceleration operation means is switched between the normal operation mode and the abnormal operation mode, the target deceleration calculated by the switched mode is changed. Since the correction is made by the correction amount corresponding to the deviation between the target decelerations calculated before and after the switching of the calculation mode, the target deceleration is surely prevented from rapidly changing.

[0016]

According to a preferred aspect of the present invention, in the configuration of the second aspect, the target deceleration calculating means in the normal mode is a target deceleration calculating means based on the pressure of the master cylinder. It is configured to calculate the target deceleration based on the deceleration and the depressing stroke of the brake pedal, and calculate the final target deceleration as a weighted sum of the two target decelerations (Preferred Embodiment 1).

According to another preferred aspect of the present invention, in the configuration of the second or third aspect, the plurality of braking operation amount detecting means are two pressure sensors for detecting the pressure of the master cylinder of the braking device. And a stroke sensor for detecting the depression stroke of the brake pedal of the braking device. In the normal operation mode, the target deceleration calculating means sets a target based on the average value of the master cylinder pressure detected by the two pressure sensors. It is configured to calculate the target deceleration based on the deceleration and the depression stroke of the brake pedal, and calculate the final target deceleration as a weighted sum of the two target decelerations (preferred mode 2).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1 or 2, the weight of the two target decelerations is changed based on one of the two target decelerations. (Preferred embodiment 3).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1 or 2, the weights of the two target decelerations are the final target deceleration calculated last time or corresponding to the final target deceleration. (Preferred mode 4).

According to another preferred aspect of the present invention, in the configuration of the fourth aspect, the target deceleration change reduction means switches the operation mode between a normal operation mode and an abnormal operation mode. In this case, a deviation between the target deceleration calculated in the mode before switching and the target deceleration calculated in the mode after switching is calculated, and the target deceleration calculated in the mode after switching is corrected according to the deviation. The target deceleration calculated in the mode before switching is gradually changed from the target deceleration calculated in the mode before switching by reducing the magnitude of the correction amount with the passage of time. (Preferred mode 5).

According to another preferred aspect of the present invention, in the configuration of the fifth aspect, the target deceleration change reduction means is configured to switch the target deceleration calculated in the mode after switching to the normal operation mode. If the target deceleration calculated when the operation mode is switched to the abnormal time operation mode is smaller than the target deceleration calculated when the operation mode is switched, the target deceleration calculated by the mode after the switch to the target deceleration calculated when the operation mode is switched It is configured to reduce the magnitude of the correction amount according to the speed ratio (preferred mode 6).

[0022]

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

First Embodiment FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electronic control device of a first embodiment of a vehicle braking force control device according to the present invention. In FIG. 1, the solenoid of each solenoid on-off valve is omitted for the purpose of simplification.

In FIG. 1, reference numeral 10 denotes an electrically controlled hydraulic brake device. The brake device 10 is a master for pumping brake oil in response to a depression operation of a brake pedal 12 by a driver. It has a cylinder 14. A dry stroke simulator 16 is provided between the brake pedal 12 and the master cylinder 14.

The master cylinder 14 has a first master cylinder chamber 14A and a second master cylinder chamber 14B.
One ends of a brake hydraulic pressure supply conduit 18 for the front wheels and a brake hydraulic control conduit 20 for the rear wheels are connected to these master cylinder chambers, respectively. Brake oil pressure control conduit 1
Wheel cylinders 22FL and 22RL for controlling the braking force of the left front wheel and the left rear wheel are connected to the other ends of 8 and 20, respectively.

In the middle of the brake hydraulic pressure supply pipes 18 and 20, a normally open type solenoid on-off valve (master cut valve) 2
4F and 24R are provided, and the solenoid on-off valves 24F and 24R control the communication between the first master cylinder chamber 14A and the second master cylinder chamber 14B and the corresponding wheel cylinder, respectively. The master cylinder 14 and the solenoid on-off valve 2
A wet stroke simulator 28 is connected to the brake hydraulic pressure supply line 20 between the brake hydraulic pressure supply line 4RL and the 4RL via a normally closed type electromagnetic switching valve 26.

A reservoir 30 is connected to the master cylinder 14, and one end of a hydraulic supply pipe 32 is connected to the reservoir 30. An oil pump 36 driven by an electric motor 34 is provided in the middle of the hydraulic supply conduit 32, and an accumulator 38 for accumulating high-pressure hydraulic pressure is connected to the hydraulic supply conduit 32 on the discharge side of the oil pump 36. One end of a hydraulic discharge conduit 40 is connected to a hydraulic supply conduit 32 between the reservoir 30 and the oil pump 36.

The hydraulic supply conduit 32 on the discharge side of the oil pump 36 is connected to the brake hydraulic supply conduit 1 between the solenoid valve 24F and the wheel cylinder 22FL by a hydraulic control conduit 42.
8, a hydraulic control conduit 44 is connected to the wheel cylinder 22FR for the right front wheel, and a hydraulic control conduit 46 is connected to the brake hydraulic supply conduit 20 between the solenoid on-off valve 24R and the wheel cylinder 22RL. 4
8 is connected to a wheel cylinder 22RR for the right rear wheel.

In the middle of the hydraulic control conduits 42, 44, 46, and 48, normally closed solenoid on-off valves 50FL, 50FR,
0RL and 50RR are provided. Solenoid on-off valve 50FL, 5
Wheel cylinder 22FL for 0FR, 50RL, 50RR,
Hydraulic control conduits 42, 4 on the side of 22FR, 22RL, 22RR
4, 46 and 48 are hydraulic control conduits 52, 54 and 5 respectively.
The solenoid valves 60FL, 60FR, 60RL, and 60RR are provided in the middle of the hydraulic control conduits 52, 54, 56, and 58, respectively.

Electromagnetic valves 50FL, 50FR, 50RL, 50
RR is wheel cylinder 22FL, 22FR, 22R respectively
L, 22RR function as pressure increasing control valves, and the solenoid on-off valves 60FL, 60FR, 60RL, 60RR function as pressure reducing control valves on the wheel cylinders 22FL, 22FR, 22RL, 22RR, respectively. The pressure increase / decrease control valve controls the supply and discharge of high-pressure oil from the accumulator 38 to each wheel cylinder.

The hydraulic supply conduit 18 for the front wheels and the hydraulic control conduit 44 for the right front wheel are respectively connected to the corresponding wheel cylinders 22.
FL and 22FR are connected to each other by a connecting conduit 62F at a position close to them. A normally closed electromagnetic on-off valve 64F is provided in the middle of the connection conduit 62F, and the electromagnetic on-off valve 64F functions as a communication control valve for controlling communication between the wheel cylinders 22FL and 22FR.

Similarly, the hydraulic supply conduit 20 for the rear wheel and the hydraulic control conduit 48 for the right rear wheel are connected to the connecting conduit 6 at positions close to the corresponding wheel cylinders 22RL and 22RR, respectively.
They are connected to each other by 2R. A normally closed electromagnetic on-off valve 64R is provided in the middle of the connecting conduit 62R, and the electromagnetic on-off valve 64R functions as a communication control valve for controlling communication between the wheel cylinders 22RL and 22RR.

As shown in FIG. 1, the pressure in the brake hydraulic control conduit 18 between the first master cylinder chamber 14A and the solenoid on-off valve 24F is defined as the first master cylinder pressure Pm1. A pressure sensor (Pm1 sensor) 66 for detecting is provided. Similarly, a pressure sensor (Pm2 sensor) for detecting the pressure in the brake hydraulic control conduit 20 between the second master cylinder chamber 14B and the solenoid on-off valve 24R as a second master cylinder pressure Pm2.
68 are provided.

The brake pedal 12 is provided with a stroke sensor (Sp sensor) 70 for detecting a depression stroke Sp as a driver's braking operation amount. A hydraulic supply conduit 32 on the discharge side of the oil pump 34 is provided in the brake pedal 12. Pressure sensor 7 for detecting pressure as accumulator pressure Pa
2 are provided.

In the brake hydraulic pressure supply conduits 18 and 20 between the solenoid valves 24F and 24R and the wheel cylinders 22FL and 22RL, respectively, the pressures in the corresponding conduits are detected as the pressures Pfl and Prl in the wheel cylinders 22FL and 22RL. Pressure sensors 74FL and 74RL are provided. A hydraulic control conduit 44 between the solenoid valves 50FR and 50RR and the wheel cylinders 22FR and 22RR, respectively.
And 48 are provided with pressure sensors 74FR and 74RR for detecting the pressure in the corresponding conduits as the pressures Pfr and Prr in the wheel cylinders 22FR and 22RR.

Electromagnetic on-off valves 24F and 24R, electromagnetic on-off valve 2
6, electric motor 34, solenoid on-off valve 50FL, 50FR, 50RL,
50RR, solenoid on-off valve 60FL, 60FR, 60RL, 60RR,
The solenoid on-off valves 64F and 64R are controlled by an electric control unit 76 as described in detail later. Electric control device 7
Reference numeral 6 denotes a microcomputer 78 and a drive circuit 80.

A drive current is supplied from a battery (not shown in FIG. 1) to each of the solenoid on-off valves and the electric motor 34 via a drive circuit 80. In particular, when no drive current is supplied to each of the solenoid on-off valves and the electric motor 34 during non-control operations. The solenoid on-off valves 24F and 24R and the solenoid on-off valves 64F and 64R are maintained in the open state, and the solenoid on-off valve 26, the solenoid on-off valves 50FL, 50FR, 50
RL, 50RR, solenoid on-off valve 60FL, 60FR, 60RL, 60
RR is kept closed.

Although the microcomputer 78 is not shown in detail in FIG. 1, for example, the central processing unit (CP)
U), a read only memory (ROM), a random access memory (RAM), and an input / output port device, which have a general configuration connected to each other by a bidirectional common bus. Good.

The input / output port device of the microcomputer 78 has a signal indicating the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 from the pressure sensors 66 and 68, respectively, and a depressing stroke of the brake pedal 12 from the stroke sensor 70. The signal indicating Sp, the signal indicating the accumulator pressure Pa from the pressure sensor 72, and the wheel cylinder 2 from the pressure sensors 74FL to 74RR, respectively.
A signal indicating a pressure Pi (i = fl, fr, rl, rr) within 2FL to 22RR is input.

The ROM of the microcomputer 78 stores the braking force control flow shown in FIGS. 2 and 3 as will be described later.
Cylinder pressures Pm1, Pm detected by
Based on m2 and the depression stroke Sp of the brake pedal 12 detected by the stroke sensor 70, a final target deceleration Gt of the vehicle is calculated as described later. When the final target deceleration Gt is 0 and there is no driver's braking request, The solenoid on-off valve is maintained in an uncontrolled state, and when the final target deceleration Gt is positive and the driver has a braking request, the target braking pressure Pti (i = fl, fr, rl) of each wheel is based on the final target deceleration Gt. , R
r) is calculated to control the wheel cylinder pressure of each wheel to the target braking pressure Pti.

Further, the electric control device 76 is required based on the accumulator pressure Pa detected by the pressure sensor 72 so that the pressure in the accumulator is maintained at a pressure not less than a predetermined lower limit value and not more than an upper limit value. Accordingly, the electric motor 34 is driven to operate the oil pump 36.

The electric control unit 76 detects abnormalities in these sensors based on the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 and the depression stroke Sp of the brake pedal 12 detected by the stroke sensor 70, respectively. It is determined whether or not any of the sensors has occurred. If any of the sensors has an abnormality, the final target deceleration Gt is calculated based on the master cylinder pressure or the depressing stroke detected by the normal sensor. This prevents the final target deceleration Gt from abruptly changing like a step due to the change between the state and the abnormal state.

Next, the braking force control in the illustrated embodiment will be described with reference to the flowcharts shown in FIGS. The control according to the flowcharts shown in FIGS. 2 and 3 is started when an ignition switch (not shown) is turned on, and is repeatedly executed at predetermined time intervals.

First, in step 10, signals indicating the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 detected by the pressure sensors 66 and 68 are read, and in step 20, Calculates the target deceleration Gst based on the depression stroke Sp from the map corresponding to the graph shown in FIG.

In step 30, the average value Pma of the first and second master cylinder pressures Pm1 and Pm2 is calculated, and in step 40, the first and second master cylinder pressures Pm1 and Pm2 are calculated from the map corresponding to the graph shown in FIG. Second master cylinder pressure P
A target deceleration Gpt based on the average value Pma of m1 and Pm2 is calculated.

In step 50, the pressure sensor (Pm1
It is determined whether or not the sensor 66 is normal, and if a negative determination is made, a target based on the second master cylinder pressure Pm2 is obtained from the map corresponding to the graph shown in FIG. After the deceleration Gpt is calculated, the routine proceeds to step 90, and when an affirmative determination is made, the routine proceeds to step 70.

In step 70, the pressure sensor (Pm2
It is determined whether or not the sensor 68 is normal. If a negative determination is made, a target based on the first master cylinder pressure Pm1 is determined in step 80 from a map corresponding to the graph shown in FIG. After the deceleration Gpt is calculated, the routine proceeds to step 90, and when a positive determination is made, the routine proceeds to step 90.

In step 90, it is determined whether or not the stroke sensor (Sp sensor) 70 is normal. If a negative determination is made, in step 100, the final target deceleration Gt is set to the target deceleration. Gpt is set, and when a positive determination is made, the routine proceeds to step 110.

The determination as to whether or not each sensor is normal in steps 50, 60, and 70 does not constitute the gist of the present invention, but is performed in any manner known in the art. May be.

In step 110, based on the final target deceleration Gt calculated in the previous cycle, a weight α (0 ≦ α ≦ 1) for the target deceleration Gpt from a map corresponding to the graph shown in FIG. In step 120, the final target deceleration Gt is calculated as the weighted sum of the target deceleration Gpt and the target deceleration Gst according to the following equation 1. Gt = αGpt + (1−α) Gst (1)

In step 130, FIG.
The deviation ΔGt of the final target deceleration Gt is calculated according to the calculation routine shown in FIG.
The final target deceleration Gt is corrected in accordance with the correction routine shown in FIG.

In step 240, it is determined whether or not the final target deceleration Gt is positive, that is, whether or not the braking force needs to be controlled. In step 250, each solenoid on-off valve is controlled to the non-control position.
0, the coefficient (positive constant) of the target wheel cylinder pressure of each wheel with respect to the final target deceleration Gt is Ki (i = fl, f
The target wheel cylinder pressure Pti (i = fl, fr, rl, rr) of each wheel is calculated as r, rl, rr according to the following equation 2, and in step 270, the wheel cylinder pressure of each wheel is reduced to the target braking. The pressure is controlled to be Pti. Pti = K
i Gt …… (2)

In step 132 of the routine for calculating the deviation ΔGt of the final target deceleration Gt shown in FIG. 4, it is detected that the pressure sensor (Pm1 sensor) 66 has now changed from a normal state to an abnormal state. When a negative determination is made, the routine proceeds to step 138, and when an affirmative determination is made, in step 134 the deviation ΔGt1 includes the master cylinder pressure Pm1 detected by the pressure sensor 66. Calculated final target deceleration G
The difference ΔGt is calculated as ΔGt1 in step 136 by calculating the difference between t and the final target deceleration Gt calculated excluding the master cylinder pressure Pm1 detected by the pressure sensor 66.

In step 138, the pressure sensor (P
It is determined whether or not the m2 sensor 68 has been changed from a normal state to an abnormal state this time. If a negative determination is made, the process proceeds to step 144, and if an affirmative determination is made, step 140 is performed. The master cylinder pressure P at which the deviation ΔGt2 is detected by the pressure sensor 68
m2 and the final target deceleration Gt calculated by excluding the master cylinder pressure Pm2 detected by the pressure sensor 68 and the final target deceleration Gt calculated by excluding the master cylinder pressure Pm2. It is set to ΔGt2.

In step 144, it is determined whether or not the stroke sensor (Sp sensor) 70 has been changed from a normal state to an abnormal state this time. If a negative determination is made, the process proceeds to step 144. Proceeding to 152, when an affirmative determination is made, the deviation ΔGt3 in step 148 is calculated with the final target deceleration Gt including the stepping stroke Sp detected by the stroke sensor 70 and the stepping stroke detected by the stroke sensor 70. The difference from the final target deceleration Gt calculated excluding Sp is calculated, and in step 150, the difference ΔGt is set to ΔGt3.

In step 152, it is determined whether or not it has been detected that the pressure sensor (Pm1 sensor) 66 has now changed from an abnormal state to a normal state. If a negative determination is made, the process proceeds to step 152. Proceeding to 158, if an affirmative determination is made, then at step 154 the deviation ΔG
t1 is the deviation between the final target deceleration Gt calculated excluding the master cylinder pressure Pm1 detected by the pressure sensor 66 and the final target deceleration Gt calculated including the master cylinder pressure Pm1 detected by the pressure sensor 66 , And in step 156, the deviation ΔGt is set to ΔGt1.

In step 158, the pressure sensor (P
It is determined whether or not the m2 sensor) 68 has been changed from an abnormal state to a normal state this time. If a negative determination is made, the process proceeds to step 164; The master cylinder pressure P at which the deviation ΔGt2 is detected by the pressure sensor 68
The difference ΔGt is calculated in step 162 as the difference between the final target deceleration Gt calculated excluding m2 and the final target deceleration Gt calculated including the master cylinder pressure Pm2 detected by the pressure sensor 68. It is set to ΔGt2.

In step 164, it is determined whether or not the stroke sensor (Sp sensor) 70 has been changed from an abnormal state to a normal state this time. If a negative determination is made, the process proceeds to step 164. The program proceeds to 180, and when an affirmative determination is made, in step 168, the deviation ΔGt3 is calculated with the final target deceleration Gt calculated excluding the stepping stroke Sp detected by the stroke sensor 70 and the stepping stroke detected by the stroke sensor 70. It is calculated as a deviation from the final target deceleration Gt calculated including Sp, and in step 170, the deviation ΔGt is set to ΔGt3.

In step 182 of the final target deceleration Gt correction routine shown in FIG. 5, it is determined whether or not the absolute value of the deviation ΔGt of the final target deceleration exceeds the reference value β (positive constant). When the determination is made and the negative determination is made, the deviation ΔGt is set to 0 in step 184, and when the affirmative determination is made, the process proceeds to step 186.

In step 186, it is determined whether or not the deviation ΔGt of the final target deceleration is positive. If the determination is affirmative, in step 188, ΔGtf is changed to the deviation ΔGt of the final target deceleration. The deviation ΔGt is set to ΔGtf−β as the previous value of, and when a negative determination is made, the deviation ΔGt is set to ΔGtf + β in step 190.

In step 192, the final target deceleration Gt is set in step 100 or the final target deceleration Gt calculated in step 120 and set in steps 184, 188 or 190. The deviation is corrected to the sum of the deviation ΔGt, and then the routine proceeds to step 210.

Thus, according to the first embodiment, the target deceleration Gst based on the depression stroke Sp is calculated in step 20, and the first and second master cylinder pressures Pm1 and Pm2 are calculated in steps 30 and 40. Is calculated based on the average value Pma of the pressure sensor 6
6, 68 and the stroke sensor 70 are normal, the weight .alpha. For the target deceleration Gpt is calculated in step 110 based on the final target deceleration Gt calculated in the previous cycle. A final target deceleration Gt is calculated as a weighted sum of the speed Gpt and the target deceleration Gst.

When the pressure sensor 66 is abnormal, the target deceleration Gpt based on the second master cylinder pressure Pm2 is calculated in step 60, and when the pressure sensor 68 is abnormal, the first deceleration Gpt is calculated in step 80. A target deceleration Gpt based on the master cylinder pressure Pm1 is calculated, and a weight α for the target deceleration Gpt is calculated based on the final target deceleration Gt calculated in the previous cycle in step 110, and in step 120 Target deceleration Gpt
The final target deceleration Gt is calculated as a weighted sum of the target deceleration Gst and the target deceleration Gst.

Further, when the stroke sensor 70 is abnormal, in step 100, the final target deceleration Gt is set to the target deceleration Gpt based on the average value Pma of the first master cylinder pressure Pm1 and the second master cylinder Pm2. You.

If the final target deceleration Gt is positive and it is necessary to control the braking force of each wheel, step 240
In step 260, the target wheel cylinder pressure Pti of each wheel with respect to the final target deceleration Gt is calculated, and in step 270, the wheel cylinder pressure of each wheel becomes the target braking pressure Pti. Is controlled as follows.

Therefore, according to the first embodiment shown, when the pressure sensors 66, 68 and the stroke sensor 70 are normal, the master cylinder pressures Pm1, Pm2 and the stroke sensor 7, which are detected by the pressure sensors 66, 68, respectively.
Since the final target deceleration Gt is calculated based on both the depressing stroke Sp detected by 0, the braking force of the vehicle can be accurately controlled according to the driver's braking operation amount.

If an abnormality occurs in the pressure sensor 66 or 68, the final target deceleration Gt is calculated based on the master cylinder pressure Pm1 or Pm2 detected by the normal pressure sensor and the depression stroke Sp, and the stroke sensor 7
If an error occurs in the master cylinder pressures Pm1 and Pm2
, The final target deceleration Gt is calculated based on the abnormal target cylinder deceleration Gt. Power control can be reliably prevented, and braking force control according to the amount of braking operation performed by the driver can be reliably continued even if an abnormality occurs in the pressure sensor or the stroke sensor.

In particular, according to the illustrated embodiment, step 1
30, ie, the deviation Δ of the final target deceleration Gt shown in FIG.
In steps 132 to 150 of the Gt calculation routine,
When it is detected that the pressure sensor or the stroke sensor has become abnormal from the normal state, the final target deceleration Gt calculated including the detection result of the abnormal sensor and the detection result of the abnormal sensor are excluded. The calculated deviation ΔGt from the final target deceleration Gt is calculated.
When it is detected that the pressure sensor or the stroke sensor has changed from the abnormal state to the normal state in steps 166 to 166, the final target deceleration Gt calculated excluding the detection result of the abnormal sensor and the abnormal sensor The deviation ΔGt from the final target deceleration Gt calculated including the detection result is calculated, and step 140, that is, the final target deceleration Gt shown in FIG.
In steps 182 to 192 of the correction routine, the final target deceleration Gt is corrected by the deviation ΔGt and the deviation ΔG
The magnitude of t is gradually reduced.

Therefore, when it is detected that the pressure sensor or the stroke sensor has become abnormal from the normal state, and when it is detected that the pressure sensor or the stroke sensor has become normal from the abnormal state. In any case, when the change in the state of the sensor is detected, the final target deceleration Gt rapidly fluctuates in a step-like manner, and the braking force of each wheel fluctuates rapidly due to this. It is possible to reliably prevent the steering stability of the vehicle from deteriorating and the driver from feeling uncomfortable.

For example, as shown in FIG. 9, in a situation where the pressure sensor (Pm2 sensor) 68 has an abnormal decrease in gain, the driver starts depressing the brake pedal 12 at time t1. As a result, the stepping stroke Sp, the first master cylinder pressure Pm1, the second master cylinder pressure Pm2, and the average value Pma of the first and second master cylinder pressures gradually increase. It is assumed that an abnormality of the pressure sensor 68 is detected when the deviation between the master cylinder pressure Pm1 and the second master cylinder pressure Pm2 becomes equal to or larger than a reference value.

The target deceleration Gst based on the depression stroke Sp does not fluctuate abruptly even at the time t2.
As shown in the second row from the bottom, the target deceleration Gpt is equal to the first and second master cylinder pressures Pm at time t2.
The target deceleration Gpt based on the first master cylinder pressure Pm1 from the target deceleration Gptma based on the average value Pma of 1 and Pm2
As a result, the final target deceleration Gt also changes abruptly at time t2, as shown by a thick imaginary line at the bottom of FIG. Is inevitable. In FIG. 9, Gptm2 indicates a target deceleration based on the second master cylinder pressure Pm2 (the same applies to FIG. 13 described later).

On the other hand, according to the first embodiment shown in the figure, as shown by the solid line at the bottom of FIG.
Between time t2 and time t3, the final target deceleration Gt is equal to the target deceleration Gst based on the depressed stroke Sp detected by the normal stroke sensor 70 from the value calculated immediately before time t2. Pressure sensor 66
Gradually changes to the value of the final target deceleration Gt calculated on the basis of the target deceleration Gptm1 based on the first master cylinder pressure Pm1 detected by the step (c). Suddenly fluctuating can be reliably prevented.

Second Embodiment FIG. 10 is a flowchart similar to FIG. 3 showing the latter half of the braking force control routine of the second embodiment, and FIG. 11 is a deviation of the final target deceleration Gt in the second embodiment. FIG. 12 is a flowchart showing a ΔGt calculation routine, and FIG. 12 is a flowchart showing a final target deceleration Gt correction routine in the second embodiment. In FIG. 10, the same steps as those shown in FIG. 3 are denoted by the same reference numerals as those in FIG.

Also in this embodiment, Step 100
Or 120, the final target deceleration G according to the calculation routine shown in FIG.
The deviation ΔGt of t is calculated.
According to the correction routine shown in FIG. 2, the final target deceleration Gt
Is corrected, and then the routine proceeds to step 240.

The final target deceleration Gt in this embodiment
In step 202 of the deviation .DELTA.Gt calculation routine, it is determined whether or not it has been detected that the pressure sensor (Pm1 sensor) 66 has now changed between a normal state and an abnormal state. Is done when step 2
Proceeding to step 10, if a negative determination is made, step 20
Proceed to 4.

In step 204, the pressure sensor (P
It is determined whether or not the m2 sensor 68 has been changed between the normal state and the abnormal state this time. If an affirmative determination is made, the process proceeds to step 210, and a negative determination is made. Sometimes the process proceeds to step 206.

In step 206, it is determined whether or not it has been detected that the stroke sensor (Sp sensor) 70 has now changed between a normal state and an abnormal state, and a negative determination is made. Sometimes step 23
0, and when a positive determination is made, step 210
In step 212, a deviation ΔGto is calculated as a deviation between the last calculated final target deceleration Gt and the currently calculated final target deceleration Gt. In step 212, the deviation ΔGt is calculated as ΔGto
Is set to

In step 232 of the final target deceleration Gt correction routine in this embodiment, the deviation Δ
The final target deceleration Gt when Gto is calculated, that is, the final target deceleration Gt calculated immediately after it is detected that any of the sensors has changed between the normal state and the abnormal state.
Is the reference value Gto, the final target deceleration G calculated this time is
It is determined whether or not t is smaller than the reference value Gto. If the determination is affirmative, the process proceeds to step 236. If the determination is negative, the process proceeds to step 234.
t is set to the previous value ΔGtf.

In step 236, the deviation ΔGt is Δ
Step 2 is performed to reduce and correct the reduction to the product of Gt and the ratio Gt / Gto of the final target deceleration Gt calculated this time to the reference value Gto.
At 38, the final target deceleration Gt is the deviation ΔGt after the correction.
The process proceeds to step 240.

Thus, according to the second embodiment, similarly to the first embodiment, the pressure sensors 66, 6
8 and the stroke sensor 70 are normal, the final target deceleration Gt is calculated based on both the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 and the depression stroke Sp detected by the stroke sensor 70. Therefore, the braking force of the vehicle can be accurately controlled according to the amount of braking operation by the driver.

When an abnormality occurs in the pressure sensor 66 or 68, the final target deceleration Gt is calculated based on the master cylinder pressure Pm1 or Pm2 detected by the normal pressure sensor and the depression stroke Sp, and the stroke sensor 7
If an error occurs in the master cylinder pressures Pm1 and Pm2
, The final target deceleration Gt is calculated based on the abnormal target cylinder deceleration Gt. Power control can be reliably prevented, and braking force control according to the amount of braking operation performed by the driver can be reliably continued even if an abnormality occurs in the pressure sensor or the stroke sensor.

In particular, according to the illustrated embodiment, step 2
00, that is, in steps 202 to 212 of the deviation ΔGt calculation routine of the final target deceleration Gt shown in FIG. 11, the pressure sensor 66, 68 or the stroke sensor 70 changes between a normal state and an abnormal state. When it is detected that the difference ΔGt between the previously calculated final target deceleration Gt and the currently calculated final target deceleration Gt is calculated, step 230, that is, the final target deceleration Gt shown in FIG. In steps 232 to 238 of the correction routine, when the final target deceleration Gt is equal to or more than the reference value Gto, the final target deceleration Gt is corrected by the deviation ΔGt, and when the final target deceleration Gt is less than the reference value Gto, the final target deceleration Gt is reduced. The speed Gt is corrected by the deviation ΔGt, and the magnitude of the deviation ΔGt is reduced according to the ratio Gto / Gt.

Consider the case where the pressure sensor (Pm1 sensor) 66 changes from a normal state to an abnormal state.
The “last target deceleration Gt calculated last time” is the pressure sensor 6
6 was normal, and thus “the previous value of the final target deceleration Gt calculated including the first master cylinder pressure Pm1 detected by the pressure sensor 66”, and “the final target deceleration Gt calculated this time”. "Is the current value of the final target deceleration Gt calculated excluding the first master cylinder pressure Pm1 detected by the pressure sensor 66 because the pressure sensor 66 is abnormal.

The same applies to the case where the pressure sensor 66 changes from an abnormal state to a normal state.
The same applies to the case where the pressure sensor 68 or the stroke sensor 70 has changed between an abnormal state and a normal state. Therefore, if the operation cycle of the control according to the flowchart shown in FIG. Thus, the deviation ΔGt can be calculated with the same accuracy as in the first embodiment.

Therefore, when it is detected that the pressure sensor or the stroke sensor has become abnormal from the normal state, and when it is detected that the pressure sensor or the stroke sensor has become normal from the abnormal state. In any case, when the change in the state of the sensor is detected, the final target deceleration Gt fluctuates abruptly like a step, and due to this, the braking force of each wheel fluctuates abruptly. It is possible to reliably prevent the driver from feeling strange.

For example, as shown in FIG. 13, when the pressure sensor (Pm2 sensor) 68 has an abnormal gain decrease, the actual master cylinder pressure Pmc is reduced to Pmc.
When it becomes o, for example, the first master cylinder pressure Pm1
It is assumed that an abnormality has occurred in the pressure sensor 68 due to the difference between the pressure and the second master cylinder pressure Pm2 being equal to or greater than the reference value.

As shown by the thick imaginary line in FIG. 13, the final target deceleration Gt is the first and second master cylinder pressures Pm1 in the region where the actual master cylinder pressure Pmc is less than Pmco. , Pm2, the target deceleration Gptma based on the first master cylinder pressure Pm1 is substantially the same as the target deceleration Gptma based on the first master cylinder pressure Pm1 in a region where the actual master cylinder pressure Pmc is equal to or higher than Pmco. And the actual master cylinder pressure Pmc becomes Pmc.
It is inevitable that the final target deceleration Gt fluctuates abruptly when stepping up and down.

On the other hand, according to the illustrated second embodiment, the final target deceleration Gt is equal to the actual master cylinder pressure Pm.
In the region where c is equal to or higher than Pmco, the first and second master cylinder pressures are calculated by calculating a value that is substantially smaller than the target deceleration Gptm1 based on the first master cylinder pressure Pm1 by the deviation ΔGto. It is substantially the same as or very close to the target deceleration Gptma based on the average value Pma of Pm1 and Pm2.

The actual master cylinder pressure Pmc is equal to Pmc
In the region less than or equal to or greater than o, the final target deceleration Gt is smaller than the target deceleration Gptm1 based on the first master cylinder pressure Pm1 by a deviation ΔGto as the actual master cylinder pressure Pmc decreases (see FIG. 13). (Indicated by a thin dashed line in FIG. 1), and becomes zero when the actual master cylinder pressure Pmc becomes zero, thereby obtaining an average value Pma of the first and second master cylinder pressures Pm1 and Pm2. Is substantially the same as or very close to the target deceleration Gptma based on

Therefore, according to the second embodiment, the final target deceleration Gt rapidly changes in a stepped manner at the stage when the change in the state of the sensor is detected. It is possible to more surely prevent the steering stability of the vehicle from deteriorating due to a sudden change in the braking force and the driver feeling uncomfortable than in the first embodiment.

According to the second embodiment, even if it is detected that any one of the sensors has changed between the normal state and the abnormal state, the calculation is performed when the sensor is in the normal state. Final target deceleration Gt (substantially the target deceleration Gp
(equal to tm1), but in general, the driver determines the actual braking condition of the vehicle and adjusts the amount of depression on the brake pedal 12, so that this deviation actually causes excessive inconvenience to the driver in controlling the braking force. Never come.

In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to the above embodiment, and various other embodiments are included in the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in each of the above-described embodiments, the pressure sensor 66 for detecting the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 as a plurality of sensors for detecting the braking operation amount by the driver, respectively. Although there are provided two pressure sensors 68 and a stroke sensor 70 for detecting the depression stroke Sp of the brake pedal 12, a plurality of sensors for detecting the amount of braking operation by the driver include one pressure sensor and one stroke sensor. , A combination of two pressure sensors, a combination of two pressure sensors and two stroke sensors, or the like.

Further, in each of the above-described embodiments, steps 60 and 80 are executed when a negative determination is made in steps 50 and 70, respectively. Is performed, it is determined whether the pressure sensor (Pm2 sensor) 68 is normal and whether the stroke sensor 70 is normal. If these sensors are normal, the process proceeds to step 60. When the pressure sensor 68 is normal and the stroke sensor 70 is abnormal, the routine proceeds to step 100, where the stroke sensor 70 is normal but the pressure sensor 6
When 8 is abnormal, the final target deceleration Gt is set to the target deceleration Gst based on the stroke Sp, and when the pressure sensor 68 and the stroke sensor 70 are abnormal, the process may proceed to step 250.

Similarly, if a negative determination is made in step 70, it is determined whether or not the stroke sensor 70 is normal. If the stroke sensor 70 is normal, the process proceeds to step 80, and the stroke sensor When 70 is abnormal, the target deceleration Gptm1 is calculated from the map corresponding to the graph shown in FIG. 7 based on the first master cylinder pressure Pm1, and the final target deceleration Gt is set to the target deceleration Gptm1. It may be modified to proceed to step 130.

In each of the above embodiments, when a change between the normal state and the abnormal state of the sensor is detected, the final target deceleration Gt itself is corrected regardless of the type of the sensor. Although a sudden change is prevented, if the sensor detecting the change between the normal state and the abnormal state is the pressure sensor 66 or 68, the target deceleration Gpt is corrected according to the present invention. By doing so, it may be modified so that a sudden change in the final target deceleration Gt is indirectly prevented.

In the above embodiments, the weight α of the target deceleration Gpt is calculated based on the final target deceleration Gt calculated in the previous cycle. It may be calculated based on Gpt or Gst.

Further, in the above-described first embodiment, the reference value β is a positive constant, but the rate of change of the braking operation amount by the driver, for example, the magnitude of the time differential value of the final target deceleration Gt May be variably set in accordance with the rate of change in the amount of braking operation by the driver so that the larger the value is, the larger the value becomes.

[0099]

As is apparent from the above description, according to the first aspect of the present invention, any one of the braking operation amount detecting means has changed between a normal state and an abnormal state. Even if detected, the target deceleration can be reliably prevented from suddenly fluctuating, thereby causing a sudden change in the braking force and, due to this, deteriorating the driving stability of the vehicle or causing the driver to fail. Can be reliably prevented from feeling uncomfortable.

According to the second aspect of the present invention, when the pressure sensor and the stroke sensor are normal, it is possible to accurately determine the amount of braking operation on the braking operation member by the driver based on both the pressure of the master cylinder and the depression stroke. The target deceleration of the vehicle is calculated, whereby the braking force of each wheel can be accurately controlled according to the driver's braking request, and the pressure sensor or the stroke sensor can be switched between a normal state and an abnormal state. Even when it is detected that the target deceleration has changed, it is possible to reliably prevent the target deceleration from fluctuating rapidly.

According to the third aspect of the present invention, when the two pressure sensors are normal, the amount of braking operation on the braking operation member by the driver based on the average value of the master cylinder pressure detected by the two pressure sensors. Calculates the target deceleration of the vehicle accurately according to the braking force of each vehicle, thereby accurately controlling the braking force of each wheel according to the braking request of the driver. Even when it is detected that the target deceleration has changed during a short time, it is possible to reliably prevent the target deceleration from suddenly fluctuating. Claim 4
According to the configuration, when the calculation mode of the target deceleration calculation means is switched between the normal calculation mode and the abnormal calculation mode, the target deceleration is switched from the target deceleration calculated by the mode before switching. The target deceleration is gradually changed to the target deceleration calculated by the above mode, so that the target deceleration does not suddenly fluctuate when the calculation mode switches between the normal calculation mode and the abnormal calculation mode. can do.

According to the fifth aspect of the present invention, when the operation mode of the target deceleration operation means is switched between the normal operation mode and the abnormal operation mode, the target deceleration calculated in the post-switch mode is changed. Since the correction is made with the correction amount corresponding to the deviation between the target deceleration calculated before and after the change of the calculation mode, the target is set when the calculation mode is switched between the normal calculation mode and the abnormal calculation mode. A sudden change in deceleration can be reliably prevented.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a first half of a braking force control routine according to the first embodiment.

FIG. 3 is a flowchart illustrating a latter half of a braking force control routine according to the first embodiment.

FIG. 4 is a flowchart showing a routine for calculating a deviation ΔGt of a final target deceleration Gt in the first embodiment.

FIG. 5 is a flowchart illustrating a final target deceleration Gt correction routine according to the first embodiment.

FIG. 6 is a graph showing a relationship between a depression stroke Sp of a brake pedal and a target deceleration Gst.

FIG. 7 shows an average value P of first and second master cylinder pressures.
It is a graph which shows the relationship between ma and target deceleration Gpt.

FIG. 8 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. 9 is a time chart showing an example of a change in a final target deceleration Gt and the like when a driver depresses a brake pedal.

FIG. 10 is a flowchart similar to FIG. 3, showing the second half of the braking force control routine of the second embodiment.

FIG. 11 shows a final target deceleration Gt in the second embodiment.
9 is a flowchart showing a deviation ΔGt calculation routine of the first embodiment.

FIG. 12 shows a final target deceleration Gt in the second embodiment.
9 is a flowchart illustrating a correction routine.

FIG. 13 is an explanatory diagram showing a relationship between an actual master cylinder pressure Pmc, a target deceleration Gpt, and a final target deceleration Gt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Brake device 12 ... Brake pedal 14 ... Master cylinder 22FL-22RR ... Wheel cylinder 66, 68 ... Pressure sensor 70 ... Stroke sensor 72, 74FL-74RR ... Pressure sensor 76 ... Electric control device

Claims (5)

[Claims] A plurality of braking operation amount detecting means for detecting an amount of braking operation of a braking operation member by a driver; an abnormality detecting means for detecting an abnormality of the plurality of braking operation amount detecting means; When an abnormality is not detected, a normal operation mode in which a target deceleration of the vehicle is calculated based on the braking operation amounts detected by the plurality of braking operation amount detecting means, and when an abnormality is detected by the abnormality detecting means, A target deceleration calculating means having an abnormal time calculation mode for calculating a target deceleration of the vehicle based on the braking operation amount detected by the braking operation amount detecting means other than the braking operation amount detecting means in which the abnormality is detected; When the calculation mode of the target deceleration calculation means is switched between the normal calculation mode and the abnormal calculation mode, A target deceleration change reduction unit that reduces a change to a target deceleration calculated in a mode after switching from the calculated target deceleration, and a control unit that controls a braking device based on the target deceleration. Braking force control device. 2. The braking device according to claim 1, wherein the plurality of braking operation amount detecting means include a pressure sensor for detecting a pressure of a master cylinder of the braking device and a stroke sensor for detecting a depression stroke of a brake pedal of the braking device. The braking force control device for a vehicle according to claim 1, wherein 3. The braking operation amount detecting means includes at least two pressure sensors for detecting a pressure of a master cylinder of the braking device, and the target deceleration calculating means is at least in the normal operation mode. 3. The braking force control device for a vehicle according to claim 1, wherein a target deceleration is calculated based on an average value of the pressure of the master cylinder detected by the two pressure sensors. 4. The target deceleration change reducing means gradually changes a target deceleration calculated in a mode before switching to a target deceleration calculated in a mode after switching. 3. The braking force control device for a vehicle according to claim 3. 5. The target deceleration change reduction means switches by a correction amount corresponding to a deviation between target decelerations calculated before and after switching between the normal operation mode and the abnormal operation mode. 4. The braking force control device for a vehicle according to claim 1, wherein a target deceleration calculated in a later mode is corrected.