JP4360142B2 - Braking force control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking force control device, and more particularly to a so-called electronically controlled braking force control device.

  As one of braking force control devices for vehicles such as automobiles, for example, as described in Patent Document 1 below, electronic control for controlling the braking force of a wheel by braking force control means in accordance with the amount of braking operation by a driver A braking force control device of the type, and when the driver requests braking with the ignition switch turned off, the ignition switch is switched on regardless of whether the driver requests braking or not Similarly, a braking force control device that can control the braking force by supplying a current to the braking force control means is conventionally known.

According to such a braking force control device, even when the ignition switch is off, when the driver requests braking, current is supplied to the braking force control means. The braking force of the wheel can be controlled according to the amount of braking operation to satisfy the driver's braking request.
JP 2002-154414 A

  Generally, in an automobile or the like, when the ignition switch is turned on, engine cranking is started. However, a large amount of current is required for engine cranking, while power is generated by an alternator. Insufficient power supply voltage temporarily decreases. Therefore, when the ignition switch is turned on when there is a braking request by the driver, or when there is a braking request by the driver with the ignition switch turned off, current is supplied to the braking force control means to control the braking force. If the ignition switch is turned on after being made possible, the braking force of each wheel by the braking force control means may not be properly controlled.

In particular, the braking force control device has a normally open type electromagnetic on / off valve (master cut valve) that controls communication between the master cylinder and the wheel cylinder of each wheel, and the normally open type electromagnetic on / off valve is closed. In the case of a configuration in which the braking force of each wheel is controlled based on the amount of braking operation of the driver by controlling the wheel cylinder pressure of each wheel using the pressure of a high pressure source, it is normally opened due to a decrease in power supply voltage. The electromagnetic open / close valve of the mold opens, the high-pressure working fluid flows back to the master cylinder, and the master cylinder pressure instantaneously increases, so that the driver may feel a pedal shock.

The present invention relates to a conventional braking force configured to control the braking force of each wheel by controlling the wheel cylinder pressure in a state where the communication between the master cylinder and the wheel cylinder is blocked by a normally open electromagnetic on-off valve. The present invention has been made in view of the above-described problems in the control device. The main problem of the present invention is that the power supply voltage is temporarily reduced by cranking the engine in a situation where the driver is required to brake. When there is a possibility that the pressure will drop, the high pressure working fluid is prevented from flowing back to the master cylinder, thereby preventing the driver from feeling a pedal shock.

According to the present invention, the above-mentioned main problem is that, according to the present invention, the electromagnetic on-off valve for controlling the communication between the master cylinder and the wheel cylinder of each wheel, and each wheel based on the braking operation amount of the driver. Control means for calculating a target wheel cylinder pressure and controlling the wheel cylinder pressure of each wheel to a corresponding target wheel cylinder pressure with the electromagnetic on-off valve closed using the pressure of a high pressure source And a braking force control device for a vehicle having an electromagnetic on-off valve and a means for supplying electric power to the control means when an ignition switch is in an on state or when a driver's braking operation is detected. The electromagnetic on-off valve is a normally-open type electromagnetic on-off valve that is closed when electric power is supplied, and the control means is configured such that the braking operation amount of the driver is a reference value. Although and engine is above is operated at a situation where the power to the engine rotational speed is less than the idle speed and the solenoid valve and the control means is supplied, the wheel cylinder pressure of each wheel This is achieved by a vehicle braking force control device that controls the pressure to be lower than the target wheel cylinder pressure.

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of claim 1, the pressure lower than the target wheel cylinder pressure is substantially the same as the master cylinder pressure. (Structure of claim 2).

According to the first aspect of the present invention, the amount of braking operation by the driver is equal to or greater than the reference value and the engine is operated, but the engine speed is less than the idle speed and power is supplied to the electromagnetic on-off valve and the control means. In such a situation, the wheel cylinder pressure of each wheel is controlled to be lower than the target wheel cylinder pressure . Accordingly, the differential pressure between the wheel cylinder pressure of each wheel and the master cylinder pressure can be reduced as compared with the case where the wheel cylinder pressure of each wheel is not controlled to a pressure lower than the target wheel cylinder pressure. Even if the power supply voltage drops temporarily due to cranking and the normally open type electromagnetic on-off valve opens temporarily, there is a risk that high-pressure hydraulic fluid will flow back to the master cylinder from the wheel cylinder side of each wheel. Therefore, it is possible to effectively reduce the driver's fear of feeling a pedal shock, and the normally open type electromagnetic on-off valve is caused by a temporary drop in the power supply voltage due to engine cranking. Temporary valve opening can be allowed.

  According to the configuration of the second aspect, since the pressure lower than the target wheel cylinder pressure is substantially the same as the master cylinder pressure, the high-pressure working liquid is reliably prevented from flowing back to the master cylinder. This can reliably prevent the driver from feeling pedal shock.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of claim 1 or 2 , the control means sets the target wheel cylinder pressure of each wheel to a value higher than the master cylinder pressure based on the braking operation amount of the driver. It is comprised so that it may calculate (Preferred aspect 1).

According to another preferred aspect of the present invention, in the configuration of claim 1 or 2 , the control means sets the target wheel cylinder pressure of each wheel to be higher than the target wheel cylinder pressure based on the braking operation amount of the driver. By setting to a low pressure, the wheel cylinder pressure of each wheel is controlled to be lower than the target wheel cylinder pressure (preferred aspect 2).

According to another preferred aspect of the present invention, in the configuration according to claim 1 or 2, the control means is configured to control the target wheel cylinder of each wheel based on the master cylinder pressure and the operation displacement amount of the brake operator by the driver. It is comprised so that a pressure may be calculated (Preferred aspect 3 ).

According to another preferred embodiment of the present invention, in the configuration of claim 1 or 2, the control means includes a stroke simulator connected to the master cylinder via a normally closed electromagnetic on-off valve, When the ignition switch is switched on after the driver's braking operation is detected with the ignition switch off, the target wheel cylinder pressure of each wheel is calculated based on the master cylinder pressure and normally closed. The wheel cylinder pressure of each wheel is controlled to the target wheel cylinder pressure in a state where the electromagnetic solenoid valve of the mold is maintained in the closed state and the normally open electromagnetic solenoid valve is closed (Preferable Mode 4 ) .

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a hydraulic circuit of an embodiment of a vehicle braking force control apparatus according to the present invention, and FIG. 2 is a block diagram showing a control system of the embodiment shown in FIG. In FIG. 1, the solenoid of each valve is not shown for the sake of simplicity.

  In FIG. 1, reference numeral 10 denotes an electrically controlled hydraulic brake device. The brake device 10 includes a master cylinder 14 that pumps brake oil in response to a driver's depressing operation of the brake pedal 12. Have. 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, and these master cylinder chambers have a brake hydraulic pressure supply conduit 18 for the left front wheel and a brake hydraulic pressure control conduit for the right front wheel, respectively. One end of 20 is connected. Wheel cylinders 22FL and 22FR for controlling the braking force of the left front wheel and the right front wheel are connected to the other ends of the brake hydraulic pressure control conduits 18 and 20, respectively.

  In the middle of the brake hydraulic pressure supply pipes 18 and 20, normally open type electromagnetic on / off valves (master cut valves) 24L and 24R are provided, respectively. The electromagnetic on / off valves 24L and 24R are respectively connected to the first master cylinder chamber 14A and the second It functions as a shut-off valve that controls communication between the master cylinder chamber 14B and the corresponding wheel cylinders 22FL and 22FR. A wet stroke simulator 28 is connected to the brake hydraulic pressure supply conduit 18 between the master cylinder 14 and the electromagnetic open / close valve 24FL via a normally closed electromagnetic open / close valve (normally closed valve) 26.

  A reservoir 30 is connected to the master cylinder 14, and one end of a hydraulic pressure supply conduit 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 that accumulates 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 the hydraulic supply conduit 32 between the reservoir 30 and the oil pump 36. The reservoir 30, the oil pump 36, the accumulator 38, and the like function as a high pressure source for increasing the pressure in the wheel cylinders 22FL, 22FR, 22RL, and 22RR as will be described later.

  Although not shown in FIG. 1, a conduit is provided for connecting the suction-side hydraulic supply conduit 32 and the discharge-side hydraulic supply conduit 32 of the oil pump 36, and an accumulator 38 is provided in the middle of the conduit. A relief valve is provided that opens when the pressure exceeds a reference value and returns oil from the discharge-side hydraulic supply conduit 32 to the suction-side hydraulic supply conduit 32.

  The hydraulic pressure supply conduit 32 on the discharge side of the oil pump 36 is connected to the brake hydraulic pressure supply conduit 18 between the electromagnetic on-off valve 24L and the wheel cylinder 22FL by a hydraulic control conduit 42, and the electromagnetic on-off valve 24R and the wheel by a hydraulic control conduit 44. It is connected to a brake hydraulic pressure supply conduit 20 between the cylinder 22FR, a hydraulic control conduit 46 to a left rear wheel wheel cylinder 22RL, and a hydraulic control conduit 48 to a right rear wheel wheel cylinder 22RR. .

  Normally closed electromagnetic linear valves 50FL, 50FR, 50RL, and 50RR are provided in the middle of the hydraulic control conduits 42, 44, 46, and 48, respectively. The hydraulic control conduits 42, 44, 46, 48 on the side of the wheel cylinders 22FL, 22FR, 22RL, 22RR with respect to the linear valves 50FL, 50FR, 50RL, 50RR are connected to the hydraulic discharge conduit 40 by the hydraulic control conduits 52, 54, 56, 58, respectively. And normally closed electromagnetic linear valves 60FL and 60FR are provided in the middle of the hydraulic control conduits 52 and 54, respectively, and normally closed electromagnetic solenoids are provided in the middle of the hydraulic control conduits 56 and 58, respectively. There are provided normally-open electromagnetic linear valves 60RL and 60RR that are cheaper than the conventional linear valves.

  The linear valves 50FL, 50FR, 50RL, 50RR function as pressure-increasing valves (holding valves) for the wheel cylinders 22FL, 22FR, 22RL, 22RR, respectively. The linear valves 60FL, 60FR, 60RL, 60RR are wheel cylinders 22FL, 22FR, 22RL, respectively. The linear valves function as pressure reducing valves for 22RR, so that these linear valves form a pressure increasing / decreasing control valve for controlling supply / discharge of high pressure oil to / from each wheel cylinder from the accumulator 38 in cooperation with each other.

  Note that the electromagnetic on / off valves 24L and 24R are kept open during non-control when no drive current is supplied to the electromagnetic on / off valves, linear valves and motor 34, and the electromagnetic on / off valves 26, linear valves 50FL to 50RR, linear valves 60FL and 60FR is maintained in a closed state, and linear valves 60RL and 60RR are maintained in an open state (non-control mode). In addition, when any one of the linear valves 50FL to 50RR and the linear valves 60FL to 60RR is lost and the pressure in the corresponding wheel cylinder cannot be normally controlled, each electromagnetic on-off valve is set to the non-control mode. As a result, the pressure in the wheel cylinders of the left and right front wheels is directly controlled by the master cylinder 14.

  As shown in FIG. 1, a brake hydraulic pressure control conduit 18 between the first master cylinder chamber 14A and the electromagnetic on-off valve 24L detects a pressure in the control conduit as a first master cylinder pressure Pm1. One pressure sensor 66 is provided. Similarly, the brake pressure control conduit 20 between the second master cylinder chamber 14B and the electromagnetic on-off valve 24R is provided with a second pressure sensor 68 for detecting the pressure in the control conduit as the second master cylinder pressure Pm2. It has been. The brake pedal 12 is provided with a stroke sensor 70 for detecting a brake pedal depression stroke St by a driver, and a pressure for detecting the pressure in the conduit as an accumulator pressure Pa is provided in a hydraulic supply conduit 32 on the discharge side of the oil pump 34. A sensor 72 is provided.

  Pressure sensors for detecting the pressure in the corresponding conduits as the pressures Pfl and Pfr in the wheel cylinders 22FL and 22FR are provided in the brake hydraulic pressure supply conduits 18 and 20 between the electromagnetic on-off valves 24L and 24R and the wheel cylinders 22FL and 22FR, respectively. 74FL and 74FR are provided. Further, in the hydraulic control conduits 46 and 48 between the electromagnetic on-off valves 50RL and 50RR and the wheel cylinders 22RL and 22RR, respectively, pressure sensors for detecting the pressure in the corresponding conduits as the pressures Prl and Prr in the wheel cylinders 22RL and 22RR. 74RL and 74RR are provided.

  The electromagnetic on / off valves 24L and 24R, the electromagnetic on / off valve 26, the motor 34, the linear valves 50FL to 50RR, and the linear valves 60FL to 60RR are controlled by an electronic control unit 78 shown in FIG. 2 as will be described in detail later. The electronic control unit 78 includes a microcomputer 80 and a drive circuit 82. Although not shown in detail in FIG. 1, the microcomputer 80 has, for example, a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus. It may be.

  In the microcomputer 80, a signal indicating the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 from the pressure sensors 66 and 68, a signal indicating the depression stroke St of the brake pedal 12 from the stroke sensor 70, and a pressure sensor 72, respectively. A signal indicating the accumulator pressure Pa and a signal indicating the pressure Pi (i = fl, fr, rl, rr) in the wheel cylinders 22FL to 22RR are input from the pressure sensors 74FL to 74RR, respectively, and an ignition switch (IGSW) 84 and A signal indicating whether or not the ignition switch 84 is in an ON state and a signal indicating whether or not the brake pedal 12 is depressed, a signal indicating the power supply voltage E from the power supply circuit 90, and an engine, respectively, from the stop lamp switch (STPSW) 86 Engine rotation from controller 94 Signal indicating Ne is input.

  The electronic control unit 78 includes a standby control circuit 88. When the door not shown is opened and closed when the ignition switch 84 is OFF, the power supply circuit 90 causes the microcomputer 80, pressure Electric power is supplied to the sensors 66 and 68 and the stroke sensor 70, thereby making the microcomputer 80 and these sensors operable to bring the electronic controller 78 into a standby state. When the ignition switch 84 is turned on while the electronic control unit 78 is in the standby state, power is supplied from the power supply circuit 90 to the other sensors and drive circuit 82, and the other sensors and drive circuit 82 also operate. As a result, the electronic control device 78 is activated.

  The power supply circuit 90 is always connected to the stop lamp switch 86. When the stop lamp switch 86 is turned on when the brake pedal 12 is depressed, the stop lamp 92 is turned on and the top lamp switch 86 is turned on. A signal indicating the state is supplied to the microcomputer 80. The microcomputer 80 stores a power supply control and braking force control routine according to the flowchart shown in FIG. 3 as will be described later, and when the electronic control device 78 is activated by switching the ignition switch 84 on, When the brake pedal 12 is depressed, the electromagnetic on-off valve 26 is opened and the electromagnetic on-off valves 24L and 24R are closed. In this state, the master cylinder pressures Pm1, Pm2 and stroke sensors detected by the pressure sensors 66, 68 are opened. Based on the depression stroke St detected from 70, the target wheel cylinder pressure Pti (i = fl, fr, rl, rr) of each wheel is calculated to be higher than the master cylinder pressures Pm1, Pm2, and the braking pressure Pi of each wheel is calculated. Each linear valve 50FL-50RR and 60FL-60RR is controlled so that becomes the target wheel cylinder pressure Pti. To (normal control mode).

  On the other hand, when the electronic control unit 78 is activated by depressing the brake pedal 12 when the microcomputer 80 and each sensor are in the standby state, the microcomputer 80 opens the electromagnetic on-off valve 26 and opens the electromagnetic on-off. The valves 24L and 24R are closed. In principle, the target wheel of each wheel is based on the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 and the depression stroke St detected by the stroke sensor 70 in that state. The cylinder pressure Pti (i = fl, fr, rl, rr) is calculated to a value higher than the master cylinder pressure Pm1, Pm2, and each linear valve 50FL-50RR is set so that the braking pressure Pi of each wheel becomes the target wheel cylinder pressure Pti. And 60FL to 60RR (control mode when the brake pedal is depressed).

  As will be understood from the above description, the microcomputer 80 calculates the target wheel cylinder pressure of each wheel based on the braking operation amount of the driver, and the electromagnetic on / off valves 24L and 24R, the electromagnetic on / off valve 26, the electric motor 34, and the linear valves 50FL to 50RR. In addition, the solenoid valves 24L and 24R are closed using the pressure of the high pressure source in cooperation with the sensors such as the linear valves 60FL to 60RR, the electronic control device 78, and the pressure sensor 66. Control means for controlling the wheel cylinder pressure to become the corresponding target wheel cylinder pressure is configured.

  In the illustrated embodiment, in both the normal control mode and the brake pedal depression start-up control mode, the microcomputer 80 has a driver's braking request because the driver's braking operation amount is equal to or greater than a reference value. When the engine speed Ne is less than the reference value in the situation, the target wheel cylinder pressure Pti of each wheel is set to the average value Pma of the master cylinder pressures Pm1 and Pm2, and thereby the wheel cylinder pressure Pi of each wheel. And the master cylinder pressures Pm1 and Pm2 are set to the same pressure, and even if the power supply voltage E is temporarily decreased due to engine cranking and the electromagnetic on / off valves 24L and 24R are temporarily opened, It prevents the high pressure oil from flowing back from the wheel cylinder side to the master cylinder 14 and kickback of the brake pedal 12 due to this.

  Next, the braking force control in the embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 3 is started when the microcomputer 80 is started, and is repeatedly executed at predetermined time intervals.

  First, in step 10, for example, whether or not the power supply voltage is normal is determined by determining whether or not the power supply voltage E is equal to or higher than the reference value Eo. If negative determination is made, the process proceeds to step 40. The process proceeds to step 20 when an affirmative determination is made. The reference value Eo is set to a minimum voltage necessary for the electronic control device 78 to operate normally, for example.

  In step 20, it is determined whether or not there is a braking request by the driver. If a negative determination is made, the process proceeds to step 40. If an affirmative determination is made, the process proceeds to step 30. Whether or not there is a braking request by the driver is determined by, for example, whether the average value Pma of the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 is equal to or greater than the start reference value Pms (positive constant) or It may be performed by determining whether or not the stepping stroke St detected by the stroke sensor 70 is greater than or equal to the start reference value Sts (positive constant).

  In step 30, the electromagnetic on-off valve 26 is opened or maintained, and the electromagnetic on-off valves 24L and 24R are closed or maintained, whereby the master cylinder 14 and the wet stroke are maintained. The simulator 28 is connected in communication, and communication between the master cylinder 14 and the wheel cylinders 22FL, 22FR, 22RL, and 22RR of each wheel is blocked. In step 40, the electromagnetic on-off valve 26 is closed, and the electromagnetic on-off valves 24L and 24R are opened, whereby the communication between the master cylinder 14 and the wet stroke simulator 28 is shut off and the master cylinder 14 is opened. And wheel cylinders 22FL, 22FR, 22RL, and 22RR of each wheel are connected in communication.

  In step 50, it is determined whether or not the engine not shown in the drawing is operating based on a signal from the engine control device 94. If a negative determination is made, the process proceeds to step 70 as it is. When the determination is made, the process proceeds to step 60.

In step 60, it is determined whether or not the engine speed Ne is less than a reference value Neo (positive value). If an affirmative determination is made, the process proceeds to step 120, and if a negative determination is made. Proceed to step 70. The reference value Neo is set to the minimum value of the engine speed at which an alternator not shown in the figure can stably generate power , that is, the idle speed.

  In step 70, a signal indicating the master cylinder pressure Pm1 detected by the pressure sensor 66 is read, and a map corresponding to the graph shown in FIG. 4 based on the average value Pma of the master cylinder pressures Pm1 and Pm2. Thus, the target deceleration Gpt based on the master cylinder pressure is calculated.

  In step 80, based on the depression stroke St detected by the stroke sensor 70, a target deceleration Gst based on the depression stroke is calculated from a map corresponding to the graph shown in FIG.

In step 90, the weight α (0 ≦ α ≦ 1) for the target deceleration Gpt is calculated from the map corresponding to the graph shown in FIG. 6 based on the previous final target deceleration Gtf, and the following equation is used: According to 1, the final target deceleration Gt is calculated as a weighted sum of the target deceleration Gpt and the target deceleration Gst. In the illustrated embodiment, the weight α is calculated based on the previous final target deceleration Gtf, but may be modified to be calculated based on the target deceleration Gpt or Gst.
Gt = α · Gpt + (1−α) Gst (1)

In step 100, Ki (i = fl, fr, rl, rr) is defined as a coefficient of the target wheel cylinder pressure of each wheel with respect to the final target deceleration Gt (a positive coefficient considering the braking effectiveness coefficient of each wheel). The target wheel cylinder pressure Pti (i = fl, fr, rl, rr) of each wheel is calculated according to the following formula 2.
Pti = Ki ・ Gt (2)

In step 110, coefficients Kf and Kr are calculated from a map corresponding to the graph shown in FIG. 7 based on the average value Pma of the master cylinder pressures Pm1 and Pm2, and in step 120, the target braking pressure of each wheel is calculated. Pti is calculated according to the following equations 3 and 4.
Ptfl = Ptfr = Kf · Pma (3)
Ptrl = Ptrr = Kr · Pma (4)

  In step 130, the wheel cylinder pressure Pi of each wheel is controlled by hydraulic feedback so as to become the target braking pressure Pti calculated in step 00 or 120, respectively.

  Thus, according to the illustrated embodiment, when the driver performs a braking operation in a situation where the power supply voltage E is normal and the engine is operated at a rotational speed equal to or higher than the reference value Neo, step 10, An affirmative determination is made at 20, 50, and a negative determination is made at step 60, whereby the wheel cylinder pressure Pi of each wheel is greater than the master cylinder pressures Pm1, Pm2 at steps 70-100 and 130. The electromagnetic on-off valves 24L and 24R are controlled in a brake-by-wire manner so that the target braking pressure Pti is high.

On the other hand, the power supply voltage E is normal, but the driver is performing a braking operation or the driver is performing a braking operation in a situation where the engine is operated at a rotational speed less than the reference value Neo. If the engine is running but the engine speed Ne is less than the reference value Neo and there is a driver's braking request, as in the situation where the engine is started, affirmative in steps 10, 20, 50 In addition to the determination, an affirmative determination is also made in step 60, whereby the wheel cylinder pressure Pi of each wheel is equal to the average value Pma of the master cylinder pressures Pm1 and Pm2 in steps 110, 120 and 130. The electromagnetic on-off valves 24L and 24R are controlled in a brake-by-wire manner so that the braking pressure Pti is obtained.

  Therefore, even if the power supply voltage E temporarily decreases due to engine cranking and the electromagnetic on-off valves 24L and 24R are temporarily opened, high pressure oil is supplied from the wheel cylinder side of each wheel to the master cylinder 14. Thus, it is possible to reliably prevent the driver from feeling a shock due to the kickback of the brake pedal 12 due to the reverse flow of the high-pressure oil to the master cylinder 14. be able to.

It should be noted that the engine is being operated but the engine speed Ne is less than the reference value Neo and the driver's braking request does not continue for a long time, and the driver depresses the brake pedal 12. Thus, the braking force of the wheels can be increased, so that no excessive inconvenience is caused by setting the target wheel cylinder pressure Pti of each wheel to the average value Pma of the master cylinder pressures Pm1 and Pm2.

  Further, when the brake pedal 12 is depressed by the driver while the ignition switch 84 is off, the electronic control device 78 operates in the control mode when the brake pedal is depressed, unless the engine is started. Therefore, a negative determination is made in step 50, so that the wheel cylinder pressure Pi of each wheel is determined in steps 110, 120 and 130 as in the normal control mode. Is controlled in a brake-by-wire manner with the electromagnetic on-off valves 24L and 24R closed so that the target braking pressure Pti is equal to the average value Pma of the master cylinder pressures Pm1 and Pm2.

In particular, according to the illustrated embodiment, if the engine is running but the engine speed Ne is less than the reference value Neo and there is a driver's braking request, then in step 110 based on the master cylinder pressure Pm. The coefficients Kf and Kr are calculated from the map corresponding to the graph shown in FIG. 7. The coefficients Kf and Kr are larger than 1 in the region where the average value Pma of Pm1 and Pm2 is high. Since the calculation is performed so as to gradually increase, the braking force of the wheel can be reliably controlled to a high value according to the request when the degree of the driver's braking request is very high.

  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 are possible within the scope of the present invention. It will be apparent to those skilled in the art.

For example, in the above-described embodiment, when the engine is operated but the engine speed Ne is less than the reference value Neo and there is a driver's braking request, the coefficients Kf and Kr are set to 1 in principle. By setting the target wheel cylinder pressure Pti of the wheel to the average value Pma of the master cylinder pressures Pm1 and Pm2, the wheel cylinder pressure Pi of each wheel is controlled to a pressure lower than the original target wheel cylinder pressure. However, the wheel cylinder pressure Pi of each wheel is reduced to a pressure lower than the original target wheel cylinder pressure, and the backflow of high-pressure oil from the wheel cylinder side of each wheel to the master cylinder 14 is suppressed. As long as the kickback of the brake pedal 12 is reduced, the coefficients Kf and Kr may be larger than 1.

  In the above embodiment, the coefficients Kf and Kr are constant values (1) regardless of the average value Pma in the region where the average value Pma of Pm1 and Pm2 is low, and the region where the average value Pma is high. The coefficient Kf and Kr are calculated to be gradually larger than 1 as the average value Pma is higher. However, the coefficients Kf and Kr are 1 as the average value Pma is higher than the region where the average values Pma of Pm1 and Pm2 are lower. It may be calculated so as to be gradually larger than that, and may be modified so that it is calculated to be a constant value even in a region where the average value Pma is high.

  In the above-described embodiment, the target braking pressure Pti of each wheel is operated based on the average value Pma of the master cylinder pressures Pm1 and Pm2 as a value indicating the amount of braking operation by the driver and the depression amount St of the brake pedal. The driver's required deceleration Gt is calculated, and the target braking pressure Pti of each wheel is calculated based on the driver's required deceleration Gt, but the control of the braking force itself forms the gist of the present invention. Rather, it may be performed in any manner known in the art.

  In the above-described embodiment, the pressure increasing / reducing control valve for controlling the wheel cylinder pressure Pi of each wheel is composed of the linear valves 50FL to 50RR as pressure increasing control valves and the linear valves 60FL to 60RR as pressure reducing control valves. However, these valves may be replaced with control valves having functions of increasing and decreasing pressure and holding.

  Furthermore, although the master cylinder pressure is detected by the two pressure sensors 66 and 68, the master cylinder pressure may be corrected so as to be detected by one pressure sensor.

It is a schematic block diagram which shows the hydraulic circuit of the Example of the braking force control apparatus of the vehicle by this invention. It is a block diagram which shows the control system of the braking force control apparatus in an Example. It is a flowchart which shows the braking force control routine in an Example. It is a graph which shows the relationship between the average value Pma of a master cylinder pressure, and target deceleration Gpt. It is a graph which shows the relationship between the depression stroke St of a brake pedal, and the target deceleration Gst. It is a graph which shows the relationship between the weight (alpha) with respect to the last final target deceleration Gtf and the target deceleration Gpt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Brake device 12 Brake pedal 14 Master cylinder 22FL-22RR Wheel cylinder 24F, 24R, 26 Electromagnetic on-off valve 50FL-50RR Linear valve 60FL-60RR Linear valve 66, 68 Pressure sensor 70 Stroke sensor 72, 74FL-74RR Pressure sensor 78 Electronic control Device 84 Ignition switch 86 Stop lamp switch 88 Standby control circuit 90 Power supply circuit 94 Engine control device

Claims (2)

The electromagnetic on-off valve that controls the communication between the master cylinder and the wheel cylinder of each wheel, the target wheel cylinder pressure of each wheel is calculated based on the braking operation amount of the driver, and the pressure of the high pressure source is used to calculate Control means for controlling the wheel cylinder pressure of each wheel to the corresponding target wheel cylinder pressure with the electromagnetic on-off valve closed, and when the ignition switch is on or when the driver's braking operation is detected In a braking force control apparatus for a vehicle having the electromagnetic on-off valve and a means for supplying electric power to the control means, the electromagnetic on-off valve is a normally open type that is closed when electric power is supplied. of a solenoid valve, said control means is a braking operation by a driver is the reference value or more and engines are operated engine speed It is In the situation in which power is supplied to the idle less than the rotational speed and the solenoid valve and the control means, characterized by controlling the wheel cylinder pressure of each wheel to a pressure lower than the target wheel cylinder pressure A vehicle braking force control device.   2. The vehicle braking force control device according to claim 1, wherein the pressure lower than the target wheel cylinder pressure is substantially the same as the master cylinder pressure.

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