JP4821345B2 - Brake control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake control device that prevents occurrence of knockback due to turning of a vehicle.

  As a vehicle brake device, a disc brake is known in which a pad is pressed against a disc rotating integrally with a wheel by a wheel cylinder to generate a braking force. In this disk brake, the pad is pushed back to the disk by the vibration or inclination of the disk while the vehicle is running, and the braking responsiveness may be lowered due to an increase in the stroke of the wheel cylinder due to the pushing back (so-called knockback). In particular, when the vehicle turns, the disk is inclined and knockback is likely to occur.

  In order to prevent knockback due to turning of the vehicle, when the vehicle is detected to be turning based on the detection signal of the steering angle sensor of the steering wheel, the pad is pressed against the disc and the disc is displaced by the tilt. 2. Description of the Related Art A vehicle brake device is known (Patent Document 1).

  However, since this brake device detects the turning state of the vehicle based on the detection signal of the steering angle sensor of the steering wheel, the control for pressing the pad against the disc is started after the vehicle enters the turning state. Therefore, if the driver performs a brake operation immediately after the vehicle enters the turning state, the process of pressing the pad against the disc is not in time, and it is impossible to prevent a decrease in braking response due to an increase in the stroke of the wheel cylinder. It was.

JP 2005-67247 A

  A problem to be solved by the present invention is that a vehicle capable of preventing a decrease in braking responsiveness due to an increase in wheel cylinder stroke even when a driver performs a brake operation immediately after the vehicle enters a turning state. A brake control device is provided.

In order to solve the above problems, a turning circuit determination means for determining whether or not the road surface of the current location of the vehicle is a turning circuit, and whether or not the front road surface is a turning circuit, and the turning circuit determination means When it is determined that the road surface ahead of the vehicle is a turning circuit, the turning degree estimation means for calculating the turning degree of the vehicle in the turning circuit, and the turning circuit determination means, the road surface of the current location of the vehicle is not a turning circuit, In addition, control is performed to press the pad against the disk that rotates integrally with the wheel with a force corresponding to the degree of turning of the front road surface calculated by the turning degree estimation means from the state immediately before turning determined that the front road surface is a turning circuit. and a knock back suppression control means for performing the knock back suppression control means includes a wheel cylinder for pressing the pad to the disc by the brake fluid pressure, the wheel cylinder Proportional control valve that adjusts the differential pressure between the wheel cylinder side and the opposite side through the valve, and supplies brake fluid to the pipe between the wheel cylinder and the proportional control valve. And holding the differential pressure between the wheel cylinder side of the proportional control valve and the opposite side through the valve in a state where the pump is driven, the pad is pressed against the disk. The configuration is adopted in the vehicle brake control device.

  For example, the turning circuit determination means is configured to determine whether or not the front road surface of the vehicle is a turning circuit based on the GPS signal received by the GPS receiver and the map information read from the map information storage device. It can also be configured to determine whether or not the front road surface of the vehicle is a turning circuit based on an image captured by a CCD camera that captures the front of the vehicle, and is fixed to the ground. It can also be configured to determine whether or not the front road surface of the vehicle is a turning circuit based on a signal transmitted by the transmitter.

  For example, the turning degree estimation means calculates the turning degree of the vehicle in the turning circuit based on the turning degree of the turning circuit when the turning circuit determination means determines that the road surface ahead of the vehicle is a turning circuit. Can be configured. Further, the turning degree of the vehicle in the turning circuit may be calculated based on the speed of the vehicle when the turning circuit determination unit determines that the road surface ahead of the vehicle is a turning circuit.

  In the vehicle brake control device according to the present invention, the turning circuit determination means determines whether or not the front road surface of the vehicle is a turning circuit, and therefore starts the process of pressing the pad against the disk before the vehicle enters the turning state. Thus, an increase in the stroke of the wheel cylinder can be prevented. Therefore, even when the driver performs a braking operation immediately after the vehicle enters the turning state, the braking response is not easily lowered due to an increase in the stroke of the wheel cylinder.

  In addition, since the pad is pressed against the disc with a force according to the degree of turning of the front road surface calculated by the turning degree estimating means, even when the degree of turning of the vehicle is large, the braking by the increased stroke of the wheel cylinder is more reliably performed. A decrease in responsiveness can be prevented.

  FIG. 1 shows a piping system diagram of a brake system that employs a vehicle brake control device according to an embodiment of the present invention. This brake system has a master cylinder 2 that converts the depression force of the brake pedal 1 into hydraulic pressure, and a master reservoir 3 that stores brake fluid is attached to the master cylinder 2. The master reservoir 3 supplies brake fluid to the master cylinder 2 and collects excess brake fluid from the master cylinder 2.

  The master cylinder 2 has pressure chambers 2A and 2B. One pressure chamber 2A includes a master cylinder side pipe line 4A, a proportional control valve 5A, a pressure increase pipe line 6A, a pressure increase control valve 7RL, and a wheel cylinder side pipe line 8RL. The wheel cylinder side pipe line 8RL is connected to the pressure reducing line 11A via the pressure reducing control valve 10RL. Similarly, the pressure increase pipe line 6A is connected to the wheel cylinder 9FR via a pressure increase control valve 7FR and a wheel cylinder side pipe line 8FR, and the wheel cylinder side pipe line 8FR is connected to the pressure reduction pipe via a pressure reduction control valve 10FR. It is connected to the road 11A. The pressure increase control valves 7RL and 7FR are normally open solenoid valves, and the pressure reduction control valves 10RL and 10FR are normally closed solenoid valves.

  The wheel cylinder 9RL is operated by the hydraulic pressure supplied from the wheel cylinder side pipe line 8RL, whereby the piston (not shown) of the wheel cylinder 9RL is padded to the disk 12RL that rotates integrally with the left rear wheel (see FIG. (Not shown) and apply braking force to the left rear wheel. Similarly, the wheel cylinder 9FR also operates with the hydraulic pressure supplied from the wheel cylinder side pipe line 8FR, and presses a pad (not shown) against the disk 12FR that rotates integrally with the right front wheel.

  The pressure increasing line 6A and the pressure reducing line 11A are connected via a pump 13A. When the pump 13A is driven by the motor 14, the brake fluid is sent from the pressure reducing line 11A to the pressure increasing line 6A. A check valve 15A is provided on the discharge side of the pump 13A, and this check valve 15A prevents the backflow of the brake fluid from the pressure increasing line 6A to the pump 13A.

  The proportional control valve 5A adjusts the differential pressure between the pressure increasing pipeline 6A and the master cylinder side pipeline 4A in accordance with a control signal from a brake electronic control unit (hereinafter referred to as “brake ECU”) 33 shown in FIG. Further, the proportional control valve 5A is connected before and after via a bypass line 16A, and the bypass line 16A is provided with a check valve 17A that allows only the flow from the master cylinder side line 4A to the pressure increasing line 6A. It has been. Therefore, when a hydraulic pressure is generated in the pressure chamber 2A of the master cylinder 2 by the operation of the brake pedal 1, the hydraulic pressure is transmitted to the pressure increasing pipeline 6A through the check valve 17A regardless of the state of the proportional control valve 5A.

  Further, the pressure reducing line 11A and the master cylinder side line 4A are connected via an auxiliary reservoir 18A.

  The auxiliary reservoir 18A includes a cylinder 19A, a piston 20A that slides inside the cylinder 19A, and a spring 22A that biases the piston 20A in a direction that reduces the volume of the reservoir chamber 21A formed by the cylinder 19A and the piston 20A. Have. The reservoir chamber 21A is formed with a first port 23A connected to the master cylinder side conduit 4A and a second port 24A connected to the decompression conduit 11A. Further, the piston 20A is provided with a protrusion 25A in the piston sliding direction, while the first port 23A is provided with a valve seat 26A and a valve body 27A supported by the tip of the protrusion 25A and separated from the valve seat 26A. It has been. The valve body 27A and the valve seat 26A flow from the reservoir chamber 21A to the master cylinder side conduit 4A when the piston 20A moves in the direction in which the volume of the reservoir chamber 21A increases and the valve body 27A is seated on the valve seat 26A. A check valve that only allows

  Therefore, when hydraulic pressure is generated in the master cylinder side pipe line 4A by the operation of the brake pedal 1, the spring 20A contracts and the piston 20A moves in a direction in which the volume of the reservoir chamber 21A increases, and the valve body 27A moves to the valve seat 26A. Since the first port 23A is seated and closed, the hydraulic pressure generated in the pressure chamber 2A of the master cylinder 2 can be supplied to the wheel cylinders 9RL and 9FR. Further, when the pressure reducing control valves 10RL and 10FR are opened in this state, the brake fluid flows from the pressure reducing pipe 11A to the reservoir chamber 21A, and the hydraulic pressures in the wheel cylinder side pipes 8RL and 8FR are reduced.

  Further, when the pump 13A is driven to send brake fluid from the pressure reducing line 11A to the pressure increasing line 6A, the brake fluid in the master cylinder side line 4A flows to the pressure reducing line 11A via the auxiliary reservoir 18A. Is not overloaded.

  A hydraulic system similar to the hydraulic system connected to the pressure chamber 2A of the master cylinder 2 is also connected to the other pressure chamber 2B of the master cylinder 2, and hydraulic pressure is applied to the wheel cylinders 9FL and 9RR through the hydraulic system. Can be supplied.

  Thus, the brake system which comprised the hydraulic system piping performs normal braking with the pressure increase control valves 7RL, 7FR, 7FL, 7RR opened and the pressure reduction control valves 10RL, 10FR, 10FL, 10RR closed. Can do. In addition, when any wheel tends to lock during braking, the braking force is maintained by closing the pressure increase control valve corresponding to that wheel, or the braking force is reduced by opening the pressure reducing control valve. This eliminates the tendency of the wheels to lock.

  Further, by driving the pumps 13A and 13B, the hydraulic pressure can be supplied to the wheel cylinders 9RL, 9FR, 9FL, and 9RR regardless of the operation of the brake pedal 1, and the hydraulic pressure is proportional to the proportional control valve 5A, It can be adjusted by controlling the differential pressure before and after 5B.

  In addition, this vehicle is equipped with a navigation device. As shown in FIG. 2, the navigation device includes a destination input device 28 for inputting a destination, a GPS receiver 29 for receiving a GPS signal, a map information storage device 30 for storing map information, a GPS signal, A navigation control unit (hereinafter referred to as “navi ECU”) 31 that calculates an estimated arrival time at the destination based on the map information, and a display 32 that displays the estimated arrival time at the destination and a map around the current location. .

  The navigation ECU 31 determines the current position of the vehicle on the basis of the time when the GPS receiver 29 receives the GPS signal, the transmission time information and position information of the GPS satellites included in the GPS signal, the determined current position, Based on the destination input to the location input device 28 and the map information read from the map information storage device 30, an expected arrival time at the destination is calculated.

  Further, the navigation ECU 31 determines the traveling state of the vehicle based on the GPS signal received by the GPS receiver 29 and the map information read from the map information storage device 30, and sends a signal indicating each determination result to the brake ECU 33. .

  The brake ECU 33 outputs control signals to the proportional control valves 5A and 5B, the pressure increase control valves 7RL to 7RR, the pressure reduction control valves 10RL to 10RR, and the pump driving motor 14 in response to signals from the navigation ECU 31, respectively.

  Control of the brake system configured as described above will be described with reference to FIGS.

FIG. 3 shows the main routine of this control. First, various variables of the navigation ECU 31 and the brake ECU 33 are initialized (step S ₁ ), and input signals from each sensor are captured (step S ₂ ).

Next, a turning circuit determination for determining whether or not the road surface ahead of the vehicle is a turning circuit is executed (step S ₃ ). This turning circuit determination subroutine will be described with reference to FIG. Assuming that the GPS receiver 29 has received the GPS signal normally (step S ₁₁ ), the navigation ECU 31 converts the GPS signal received by the GPS receiver 29 and the map information read from the map information storage device 30. Based on this, it is determined whether the road surface at the current location of the vehicle is a turning circuit (step S ₁₂ ). If it is determined that the circuit is a turning circuit, the turning state is set (step S ₁₃ ), and the straight traveling state and the state immediately before turning are reset (step S ₁₄ ).

On the other hand, when it is determined that the road surface of the current location of the vehicle is not a turning circuit (step S ₁₂ ), the current location of the vehicle is determined based on the GPS signal received by the GPS receiver 29 and the map information read from the map information storage device 30. It is determined whether or not a certain range of road surface ahead (for example, a road surface within 100 m ahead of the current location) includes a turning circuit (step S ₁₅ ). When it is determined that a turning circuit is included, the state immediately before turning is set (step S ₁₆ ), and the straight traveling state and the turning state are reset (step S ₁₇ ).

If the road surface at the current position of the vehicle is not a turning circuit (step S ₁₂ ) and the front road surface does not include a turning circuit (step S ₁₅ ), a straight traveling state is set (step S ₁₈ ), and immediately before turning. The state and the turning state are reset (step S ₁₉ ).

Next, the turning degree estimation for calculating the turning degree of the vehicle in the forward turning circuit is executed (step S ₄ ). A subroutine for estimating the turning degree will be described with reference to FIG. When it is determined in the above-mentioned turning circuit determination that the state is just before turning (step S ₂₁ ), the navigation ECU 31 calculates the radius R of the front turning circuit based on the map information read from the map information storage device 30 and wheels. Based on the signal from the speed sensor, the speed V of the vehicle in the state immediately before turning is calculated (step S ₂₂ ). Thereafter, the turning degree G of the vehicle in the forward turning circuit is calculated based on the radius R of the turning circuit and the vehicle speed V (step S ₂₃ ).

Here, the turning degree G of the vehicle is a value corresponding to the pressing force of the pad necessary for suppressing the knockback, and the knockback is caused by the centrifugal force acting on the vehicle when the vehicle is turning and the disc is tilted. Therefore, it is preferable to use the lateral acceleration of the vehicle as the turning degree G of the vehicle. At this time, the turning degree G of the vehicle is generally calculated by the following equation.
G = V ² / R

Turning degree G of the vehicle calculated in this manner is sent to the brake ECU 33, the brake ECU 33 based on the turning degree G performs knock back suppression control based on the subroutine shown in FIG. 6 (step S ₅₎ . That is, when it is determined that the state is just before turning in the turning circuit determination (step S ₃₁ ), the target hydraulic pressure is calculated based on the relationship between the turning degree G and the target hydraulic pressure shown in FIG. 7 (step S ₃₁ ). _32), the liquid until a pressure wheel cylinders 9RL, 9FR, 9FL, increasing the fluid pressure in the 9RR (step _{S 33, S} 34). The increase in the hydraulic pressure until the target hydraulic pressure is reached is performed even after the turning state is reached (step S ₃₅ ).

Wheel cylinders 9RL, 9FR, 9FL, the hydraulic pressure in the 9RR reaches the hydraulic pressure in the target (step _{S 33),} to hold the hydraulic pressure in the wheel cylinders 9RL~9RR constant (step _S 36). The hydraulic pressure of the wheel cylinders 9RL to 9RR can be maintained, for example, by holding the differential pressure before and after the proportional control valves 5A and 5B constant while the pumps 13A and 13B are driven.

When neither the state just before turning nor the turning state is in effect (steps S ₃₁ and S ₃₅ ), the driving of the pumps 13A and 13B is stopped and the differential pressure before and after the proportional control valves 5A and 5B is reduced to reduce the respective wheels. releasing the hydraulic cylinder 9RL～9RR (step _S 37).

  When this vehicle brake control device is used, when the vehicle is in a state just before turning, supply of hydraulic pressure to the wheel cylinders 9RL to 9RR is started and the pads are pressed against the disks 12RL to 12RR. As shown in FIG. It is possible to prevent an increase in the stroke of each of the wheel cylinders 9RL to 9RR by closing the gap between the pad and the disk before the vehicle enters the turning state. Therefore, even when the driver performs a braking operation immediately after the vehicle enters the turning state, the braking response is not easily lowered due to an increase in the stroke of the wheel cylinder. On the other hand, in the conventional brake device, since the control of pressing the pad against the disk is started after detecting the turning state of the vehicle based on the steering angle sensor of the steering wheel or the like, as shown by the broken line in FIG. The process of pressing onto the brake is not in time for the brake operation by the driver, resulting in a decrease in braking response due to an increase in the stroke of the wheel cylinder.

  In addition, since the vehicle brake control device supplies the wheel cylinders 9RL to 9RR with hydraulic pressure having a magnitude corresponding to the turning degree G of the vehicle, the pad is discs with a force having a magnitude corresponding to the turning degree G of the vehicle. Pressed to 12RL to 12RR. For this reason, even when the centrifugal force acting on the vehicle during turning of the vehicle is large, such as when the turning circuit is bent or when the vehicle speed during turning is high, the braking response due to the increased stroke of the wheel cylinders 9RL to 9RR is more reliably achieved. A decrease can be prevented.

In the above embodiment, in order to keep the hydraulic pressure of the wheel cylinders 9RL to 9RR constant, the differential pressure before and after the proportional control valves 5A and 5B is kept constant while the pumps 13A and 13B are driven (step) _S36 ) Thus, even when the disks 12RL to 12RR are inclined and the wheel cylinders 9RL to 9RR are pushed back, an increase in the braking force due to an increase in the hydraulic pressure of the wheel cylinders 9RL to 9RR is prevented, and Although the response of braking when a braking operation is performed is enhanced, the hydraulic pressure may be kept constant by other methods. For example, the hydraulic pressures of the wheel cylinders 9RL to 9RR may be held by closing the pressure increase control valves 7RL to 7RR.

  In the above embodiment, the navigation system is used as a means for determining whether or not the road surface ahead of the vehicle is a turning circuit, so that stable determination can be performed regardless of whether the field of view ahead of the vehicle is good or bad. For example, a CCD camera that captures the front of the vehicle is installed in the vehicle, and the CCD control determines whether or not the road surface ahead of the vehicle is a turning circuit based on the image data of the CCD camera. A device may be provided, and a signal indicating the vehicle running state may be sent from the CCD control device to the brake ECU. Further, the bending degree of the turning circuit ahead of the vehicle is calculated based on the image data of the CCD camera, and the hydraulic pressure supplied to the wheel cylinders 9RL to 9RR by the brake ECU 33 immediately before the turning is increased according to the bending degree. You may make it perform control to perform.

  In addition, a receiver that receives a signal transmitted from a transmitter for road-to-vehicle communication that is fixed on the ground is installed in the vehicle, and the road surface in front of the vehicle is based on information included in the signal received by the receiver. A determination device for determining whether or not is a turning circuit may be provided. In this case, examples of the signal transmitted by the transmitter for road-to-vehicle communication include a signal indicating the approach to the turning circuit and a signal indicating the degree of bending of the turning circuit.

Piping system diagram of brake system adopting vehicle brake control device of embodiment of this invention Block diagram of the vehicle brake control device The flowchart which shows the main routine of control of the brake control apparatus for vehicles of Drawing 2 Flow diagram showing the process of step S ₃ in Fig. 3 Flow diagram showing the process of step S ₄ in FIG. 3 Flow diagram showing the process of step S ₅ in FIG. 3 The figure which shows an example of the relationship between the turning degree of a vehicle, and the target hydraulic pressure The figure explaining the timing which the process which presses a pad against a disk is started when the running state of the vehicle changes from a straight traveling state to a turning state through a state just before turning.

Explanation of symbols

12RL, 12FR, 12FL, 12RR Disc 29 GPS receiver 30 Map information storage device 31 Navigation control unit 33 Brake electronic control device

Claims (6)

The turning circuit judging means (S ₃ ) for judging whether or not the road surface at the current location of the vehicle is a turning circuit and whether the front road surface is a turning circuit and the turning circuit judging means (S ₃ ) When it is determined that the road surface of the vehicle is a turning circuit, the turning degree estimation means (S ₄ ) for calculating the turning degree of the vehicle in the turning circuit and the turning circuit determination means (S ₃ ) Since the road surface is not a turning circuit and the front road surface is determined to be a turning circuit, it is integrated with the wheels with a force corresponding to the turning degree of the front road surface calculated by the turning degree estimating means (S ₄ ). the rotating disk (12RL, 12FR, 12FL, 12RR ) knockback suppression control means for pressing control pad and a _{(S 5)} possess a,
The knockback suppression control means includes
A wheel cylinder (9RL) that presses the pad against the disc (12RL) by brake fluid pressure;
Proportional control valve (5A) provided in the middle of the pipe (8RL, 6A, 4A) connected to the wheel cylinder (9RL) to adjust the pressure difference between the wheel cylinder side and the opposite side via the valve (5A) When,
A pump (13A) for supplying brake fluid to a pipe (8RL, 6A) between the wheel cylinder (9RL) and the proportional control valve (5A);
In the state where the pump (13A) is driven, the disc (12RL) is held in the disc (12RL) by maintaining a constant differential pressure between the wheel cylinder side of the proportional control valve (5A) and the opposite side via the valve (5A). A brake control device for a vehicle, wherein the pad is pressed . Whether the front road surface of the vehicle is a turning circuit based on the GPS signal received by the GPS receiver (29) and the map information read from the map information storage device (30) by the turning circuit determination means (S ₃ ). The vehicle brake control device according to claim 1, which determines whether or not.   The vehicle brake control device according to claim 1, wherein the turning circuit determination unit determines whether or not the front road surface of the vehicle is a turning circuit based on an image captured by a CCD camera that captures the front of the vehicle.   2. The vehicle brake control device according to claim 1, wherein the turning circuit determination means determines whether or not the road surface ahead of the vehicle is a turning circuit based on a signal transmitted from a transmitter fixed on the ground. . The turning degree estimation means (S ₄ ) turns the vehicle on the turning circuit based on the turning degree of the turning circuit when the turning circuit determination means (S ₃ ) determines that the front road surface of the vehicle is a turning circuit. The vehicle brake control device according to any one of claims 1 to 4, wherein the degree is calculated. The turning degree estimating means (S ₄ ) determines the turning degree of the vehicle in the turning circuit based on the speed of the vehicle when the turning circuit determining means (S ₃ ) determines that the front road surface of the vehicle is a turning circuit. The vehicle brake control device according to any one of claims 1 to 5, wherein the vehicle brake control device is calculated.

Images