JP2012206586A - Vehicle brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure the operation of opening/closing valves when the supply of a fluid pressure is started in a vehicle brake device in which two pressure supply systems are changed over by the opening/closing valves.SOLUTION: This vehicle brake device 1 includes a brake pedal 11, a master cylinder 15, wheel cylinders 2b, 3b connected to the master cylinder through pipes 42a, 42b, the solenoid-operated opening/closing valves 24a, 24b installed in the pipes, a pedal position sensor 11a, a motor-driven cylinder 13 which is connected to the portions of the pipes which are positioned between the opening/closing valves and the wheel cylinders and which includes an electric servo-motor 12, an electric power supply 7 for supplying power to the opening/closing valves and the motor-driven cylinder, and a control unit 6. When the operation amount of the pedal reaches a start value, the control unit operably closes the opening/closing valves. In a valve closing operation period between the time when the operation amount of the pedal reaches the start value and the time when the opening/closing valves are closed, the amount of a power consumed by the electric motor is suppressed.

Description

  The present invention relates to a vehicle brake device, and more particularly to a vehicle brake device that generates a brake force by brake-by-wire.

  In some electric vehicles and hybrid vehicles, an electric motor is connected to a drive shaft of a drive wheel, and the motor is used as a generator during braking to perform energy regeneration. In such a vehicle, it may be difficult to achieve all braking force with only regenerative braking due to the motor rating, the remaining battery level, etc., and it is driven by so-called brake-by-wire by electronic control. There is a system that performs coordinated control of the hydraulic brake and the regenerative brake.

  The brake-by-wire is not mechanically connected to the brake pedal, but uses hydraulic pressure generating means that receives the position of the brake pedal as an electrical signal and supplies hydraulic pressure to the wheel cylinder in response to the signal. The The hydraulic pressure generating means is configured as, for example, a motor-driven cylinder including an electric servo motor that is driven according to a signal corresponding to the position of the brake pedal, and a piston that is driven by the electric servo motor. Also, as a fail-safe, a master cylinder that is mechanically connected to the brake pedal and generates hydraulic pressure in response to brake pedal operation is provided, and an open / close solenoid valve that is normally provided between the master cylinder and the wheel cylinder. There is one in which a master cylinder and a wheel cylinder are shut off by a valve (see, for example, Patent Document 1). That is, as a hydraulic pressure supply means, there are two systems of a motor drive cylinder and a master cylinder. While normal, the hydraulic pressure is supplied from the motor drive cylinder to the wheel cylinder, and when the motor drive cylinder etc. fails, the on-off valve The path is switched by supplying hydraulic pressure from the master cylinder to the wheel cylinder.

JP 2009-29294 A

  In the brake device as described above, in an initial state where the brake pedal is not depressed, the open / close valve is opened and the master cylinder and the wheel cylinder are communicated. When the brake pedal is depressed from the initial state and hydraulic pressure is generated in the wheel cylinder, the valve closing operation of the on-off valve and the operation of the motor drive cylinder are performed simultaneously. However, when the on-off valve and the electric servo motor of the motor drive cylinder are supplied with electric power from the same power source, as shown in FIG. 8, if the motor drive cylinder is operated at time t1, the electric servo motor Since a large starting current flows, the power supply voltage decreases and the voltage Vv supplied to the on-off valve decreases from the initial voltage Vv0 to Vv1. For this reason, even if the on-off valve is to be closed simultaneously at time t1, the voltage supplied to the on-off valve is lower than the voltage required to perform the on-off valve closing operation (startup guarantee voltage: one-dot chain line in the figure). Therefore, there is a problem that the operation of the on-off valve cannot be guaranteed.

  The present invention has been made in view of the above problems, and in a brake-by-wire vehicle brake device that switches between two pressure supply systems by an on-off valve, when hydraulic pressure supply to a wheel cylinder is started, It is an object to guarantee the operation of the on-off valve.

  In order to solve the above-described problems, the present invention provides a master cylinder (15) that is mechanically connected to a brake pedal (11) and generates hydraulic pressure, and an oil passage (42a, 42b) connected to the master cylinder. Connected wheel cylinders (2b, 3b), on-off valves (24a, 24b), which are solenoid valves provided on the oil passage, and pedal operation amounts for detecting the pedal operation amount corresponding to the operation amount of the brake pedal A detecting means (11a), a hydraulic pressure generating means (13) connected between the on-off valve of the oil passage and the wheel cylinder, and supplying a hydraulic pressure to the oil passage by driving an electric motor (12); A power supply (7) for supplying electric power to the on-off valve and the hydraulic pressure generating means, and a control means (6) for controlling the on-off valve and the hydraulic pressure generating means in accordance with the pedal operation amount. When the pedal operation amount reaches a start value at which the supply of hydraulic pressure from the hydraulic pressure generating means to the wheel cylinder is to be started, the control means controls the on-off valve. The valve closing operation period required from the time when the start value is reached to the time when the on-off valve is closed is sufficient to ensure a voltage sufficient to close the on-off valve. The power consumption of the electric motor is suppressed.

  According to this configuration, during the valve closing operation period, which is a period until the on-off valve is closed, the power consumption of the hydraulic pressure generating means is suppressed, and the voltage necessary for the valve closing operation is supplied to the on-off valve. Thereby, the operation of the on-off valve is surely performed.

  According to another aspect of the present invention, there is provided voltage detecting means (50) for detecting the voltage of the power source, wherein the control means has a voltage of the power source equal to or lower than a predetermined threshold voltage and the pedal operation amount is When the start value is reached, the electric motor is driven to close the open / close valve, and the electric motor is consumed so that a voltage sufficient to close the open / close valve can be secured during the valve closing operation period. It is characterized by suppressing the amount of electric power. The threshold voltage can be the lower limit of the voltage of the power source that can secure a sufficient voltage to close the on-off valve even when the electric motor and the on-off valve are started simultaneously.

  According to this configuration, when the power supply voltage is larger than the threshold voltage, the operation amount of the hydraulic pressure generating unit is not decreased, so that the hydraulic pressure from the hydraulic pressure generating unit is supplied to the wheel cylinder more quickly. .

  According to another aspect of the present invention, the apparatus further includes an operation amount detection unit that detects an operation amount of the fluid pressure generation unit, and the open / close valve is closed by a pressure from the fluid pressure generation unit in a closed state. The control means determines whether or not the on-off valve is in a closed state, and whether or not the hydraulic pressure generating means after the pedal operation amount reaches the start value is determined. When the operating amount of the hydraulic pressure generating means is equal to or greater than the value corresponding to the closed state of the on-off valve, the energization amount to the on-off valve is reduced from that at the time of closing the valve. It is characterized by making it.

  According to this configuration, when the on-off valve is closed, it receives the hydraulic pressure from the hydraulic pressure generating means and is urged in the valve closing direction. Therefore, the amount of electric power necessary to maintain the valve closed state Decreases. Therefore, it is possible to reduce the power supplied to the on-off valve, while increasing the power supplied to the hydraulic pressure generating means, and the operation of the hydraulic pressure generating means can be performed reliably and quickly.

  According to another aspect of the present invention, the control means makes the operating speed of the hydraulic pressure generating means smaller than the operating speed in a period other than the valve operating period in the valve closing operation period. And

  According to this configuration, it is possible to quickly generate the hydraulic pressure in the hydraulic pressure generating means while securing electric power to the on-off valve.

  According to the above configuration, in the brake-by-wire vehicle brake device that switches between the two pressure supply systems using the opening / closing valve, the operation of the opening / closing valve can be ensured when the hydraulic pressure supply to the wheel cylinder is started. .

Main part system diagram of automobile brake system according to the embodiment Hydraulic circuit diagram schematically showing a vehicle brake device according to an embodiment Sectional drawing which shows the on-off valve of the brake device of the motor vehicle which concerns on embodiment The flowchart which shows the control procedure of the control unit which concerns on embodiment The time chart which shows the effect of the brake device of the car concerning an embodiment The time chart which shows the effect of the brake device of the car concerning an embodiment The flowchart which shows the control procedure of the control unit which concerns on some deformation | transformation embodiment The figure which shows the voltage supplied to the on-off valve in a prior art

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of an essential part of a brake system of an electric vehicle or a hybrid vehicle to which the present invention is applied.

  The automobile shown in FIG. 1 has a pair of left and right front wheels 2 disposed on the front side of the vehicle V and a pair of left and right rear wheels 3 disposed on the rear side of the vehicle V. A motor / generator 5 is connected to the front wheel axle 4 connected to the left and right front wheels 2 so as to transmit torque. A differential mechanism provided on the front wheel axle 4 is not shown.

  The motor / generator 5 and a battery 7 as a secondary battery as a power source are connected via an inverter 10. The electric power of the battery 7 is supplied to the motor / generator 5 and the inverter 10 is controlled so that the electric power generated by the motor / generator 5 is supplied (charged) to the battery 7. As a result, the motor / generator 5 functions as a braking force generating means for generating a regenerative braking force by converting deceleration energy into electric power when decelerating, serving as both a vehicle running motor and a regenerative generator. Further, the battery 7 supplies power to a control unit 6 and a brake fluid pressure generating measure 8 which will be described later.

  In addition, a control unit (ECU) 6 is provided as a control unit that performs various control of the vehicle and performs braking force distribution control. The control unit 6 includes a control circuit using a CPU and is electrically connected to the inverter 10. The control unit 6 can perform regenerative cooperative control that combines regenerative braking and hydraulic braking. In the case of an electric vehicle, a rear wheel motor / generator for driving the rear wheel 3 may be provided as it is, but in the case of a hybrid vehicle, the front wheel axle 4 is indicated by a two-dot chain line in the figure. The output shaft of an engine (internal combustion engine) E shown is connected. In the case of the engine E in the figure, an example of front wheel drive is shown, but four-wheel drive can also be used.

  Each wheel of the front wheel 2 and the rear wheel 3 is constituted by a caliper including discs 2a and 3a integrated with the wheels (front wheel 2 and rear wheel 3) and wheel cylinders 2b and 3b as friction braking means for performing friction braking. A known disc brake is provided. The wheel cylinders 2b and 3b are connected to a brake fluid pressure generating device 8 constituting a braking force generating means via a known brake pipe. As will be described in detail later, the brake fluid pressure generator 8 is configured by a hydraulic circuit that can distribute the brake pressure by increasing or decreasing the brake pressure for each wheel. The brake fluid pressure generator 8 and the disc brake, and the control unit 6 that controls the brake fluid pressure generator 8 are referred to as a brake device 1.

  The front wheel 2 and the rear wheel 3 are provided with wheel speed sensors 9 for detecting wheel speeds, and the brake pedal 11 is provided with a pedal position sensor 11a for detecting a pedal position which is a position of the brake pedal 11. It has been. The pedal position sensor 11a can detect a pedal operation amount (brake operation amount) that is a driver's stepping amount, with an initial state (pedal position = 0) when the brake pedal is not depressed by the driver. The battery 7 is provided with a voltage sensor 51 for measuring the power supply voltage (V). Each detection signal of each wheel speed sensor 9, pedal position sensor 11 a and voltage sensor 51 is input to the control unit 6.

  Next, the brake fluid pressure generator 8 will be described with reference to FIG. In the braking system of the present embodiment, the operation amount (pedal operation amount) of the brake pedal 11 is detected by the pedal position sensor 11a, and the motor drive cylinder 13 as the hydraulic pressure generating means is driven based on the detected value to generate the brake fluid. Generate pressure. The motor drive cylinder 13 is integrally provided with an electric servo motor 12 and a gear box 18 connected to the electric servo motor 12, and torque is transmitted to the gear box 18 via a ball screw mechanism. Are provided with a threaded rod 19 that is displaced in the axial direction, and a first piston 21a and a second piston 21b that are coaxially arranged in series with the threaded rod 19 and in series with each other. The electric servo motor 12 is supplied with power from the battery 7.

  As a result, the electric servo motor 12 rotates in accordance with the operation amount of the brake pedal 11, the rotational force is converted into the axial force of the threaded rod 19 via the gear box 18, and the first piston 21a moves linearly. . In this way, the operation of the brake pedal 11 as the braking operation member is not mechanically transmitted to the brake hydraulic pressure generating cylinder to generate the brake hydraulic pressure, but the motor drive cylinder is generated according to the depression amount of the brake pedal 11. 13 is a so-called brake-by-wire that generates brake fluid pressure.

  One end of the arm of the brake pedal 11 is rotatably supported by the vehicle body, and one end of the rod 14 that converts the arc motion of the brake pedal 11 into a substantially linear motion is located at the middle portion of the arm of the brake pedal 11. The other end of the rod 14 is engaged so as to push in the first piston 15a of the master cylinder 15 arranged in series. In the master cylinder 15, a second piston 15b is arranged in series on the side opposite to the rod 14 with respect to the first piston 15a, and each piston 15a, 15b is connected to the rod 14 side by a return spring 41a, 41b, respectively. Is spring-biased. The brake pedal 11 is spring-biased by a return spring (not shown) so as to return to the standby position shown in FIG. 1, and is stopped by a stopper (not shown) at the standby position.

  The master cylinder 15 is provided with a reservoir tank 16 for exchanging brake fluid according to the displacement of the pistons 15a and 15b. The pistons 15a and 15b are provided with seal members having a known structure for sealing between the oil passages 16a and 16b communicating with the reservoir tank 16, respectively. And in the cylinder of the master cylinder 15, the 1st liquid chamber 17a is formed between the 1st piston 15a and the 2nd piston 15b, and it is 2nd on the side opposite to the 1st piston 15a of the 2nd piston 15b. A liquid chamber 17b is formed.

  In the motor drive cylinder 13 described above, the connecting member 27 having one end fixed to the second piston 21b extends to the first piston 21a side, and the other end in the extending direction of the connecting member 20 extends to the first piston 21a. On the other hand, it is supported so as to be displaceable by a predetermined amount in the axial direction. As a result, the first piston 21a can be displaced by a predetermined amount relative to the second piston 21b during forward movement (displacement on the second piston 21b side), but from the forward movement state of the first piston 21a to the initial state of FIG. At the time of retreating back to the second position, the second piston 21b is also pulled back to the initial position via the connecting member 20. In addition, each piston 21a * 21b is spring-biased to the rod 19 side by each return spring 27a * 27b provided corresponding to each.

  The motor drive cylinder 13 is provided with oil passages 22 a and 22 b that communicate with the reservoir tank 16 via the communication passage 22. Each piston 21a, 21b is provided with a known structure of a sealing member for sealing the space between the oil passages 22a, 22b. In the cylinder of the motor drive cylinder 13, a first liquid chamber 23a is formed between the first piston 21a and the second piston 21b, and the second liquid is disposed on the side opposite to the first piston 21a of the second piston 21b. A chamber 23b is formed.

  The first liquid chamber 17a and the second liquid chamber 17b of the master cylinder 15 communicate with a plurality of (four in the illustrated example) wheel cylinders 2b and 3b via pipes (oil passages) 42a and 42b and the VSA device 26. So connected. The VSA device 26 is a ABS that prevents wheel lock during braking, and a traction control system (TCS) that prevents wheel slipping during acceleration, etc., and suppresses slipping during turning to control the three functions in total. It may be a known stabilization control system, and its description is omitted. The VSA device 26 includes brakes using various hydraulic elements that respectively constitute a first system corresponding to each wheel cylinder 2b of the front wheel 2 and a second system corresponding to each wheel cylinder 3b of the rear wheel 3. The actuator 26b and a VSA control unit 26a for controlling them are constituted. In other embodiments, the VSA device 26 may be omitted.

  An open / close valve 24a, which is a normally open electromagnetic valve, is provided on the pipe 42a, and a normally open type open / close valve 24b, which is an electromagnetic valve, is also provided on the pipe 42b. A portion of the pipe 42a between the on-off valve 24a and the VSA device 26 is connected to communicate with the first liquid chamber 23a through the pipe 43a. A portion of the pipe 42b between the on-off valve 24b and the VSA device 26 is connected to communicate with the first liquid chamber 23a through the pipe 43b.

  The first liquid chamber 23a communicates with the first liquid chamber 17a of the master cylinder 15 via the pipe 42a, the normally open on-off valve 24a and the pipe 43a, and the second liquid chamber 23b communicates with the pipe 42b. The second liquid chamber 17b of the master cylinder 15 communicates with the mold opening / closing valve 24b and the pipe 43b. A master cylinder side brake pressure sensor 25a is connected between the first fluid chamber 17a and the on-off valve 24a, and a motor-driven cylinder side brake pressure sensor 25b is connected between the on-off valve 24b and the second fluid chamber 23b. It is connected.

  As shown in FIG. 3, the on-off valve 24a (24b) has the same configuration, and is provided in the middle of the passage 56 and the casing 56 in which the passage 55 communicating with the pipe 42a (42b) is formed. A valve seat 57; a valve body 58 seatable on the valve seat 57; a columnar plunger 59 coupled to the valve body 58; a solenoid 60 provided in the casing 56 for moving the plunger 59 forward and backward by magnetic force; The coil spring 61 is provided in the cylinder 55 and urges the plunger 59 in the direction in which the plunger 59 is retracted, and the stopper 62 is provided in the casing 56 and defines the retracted position of the plunger 59. When the solenoid 60 is not energized, the plunger 59 is retracted by the coil spring 61, the valve body 58 is separated from the valve seat 57, and the passage 55 is opened. When the solenoid 60 is energized, the plunger 59 receives the magnetic force of the solenoid 60 and moves forward against the biasing force of the coil spring 61, and the valve body 58 is seated on the valve seat 57 and closes the passage 55. In the closed state of the on-off valve 24 a in which the valve body 58 is seated on the valve seat 57, the valve body 58 is biased toward the valve seat 57 by receiving the hydraulic pressure from the motor drive cylinder 13. Therefore, the magnetic force of the solenoid 60 required to maintain the valve closing state of the on-off valve 24a is smaller than that when the valve body 58 is operated. That is, the energization amount of the solenoid 60 necessary for maintaining the closed state of the on-off valve 24a is smaller than that when the valve body 58 is operated. Electric power from the battery 7 is supplied to the solenoids 60 of the on-off valves 24a and 24b.

  A cylinder type simulator 28 is connected between the second liquid chamber 17b and the on-off valve 24b via a simulator valve 24c which is a normally closed electromagnetic valve. The simulator 28 is provided with a piston 28a that divides the cylinder, a liquid storage chamber 28b is formed on the simulator valve 24c side of the piston 28a, and a compression coil is provided on the side of the piston 28a opposite to the liquid storage chamber 28b side. A spring 28c is received. When both the on-off valves 24a and 24b are closed and the simulator valve 24c is opened, the second liquid chamber 17b and the liquid storage chamber 28b communicate with each other. When the brake pedal 11 is depressed in this state, the brake in the second liquid chamber 17b is The liquid enters the liquid storage chamber 28b. As a result, the urging force of the compression coil spring 28c to be compressed is transmitted to the brake pedal 11, so that a reaction force against the depression similar to that of a brake device in which a known master cylinder and wheel cylinder are directly connected is obtained.

  The brake hydraulic pressure generator 8 configured in this way is comprehensively controlled by the control unit 6. The control unit 6 receives detection signals from the pedal position sensor 11a and the brake pressure sensors 25a and 25b, and also receives detection signals from various sensors (not shown) for detecting the behavior of the vehicle V. In addition, a motor rotation angle signal from a motor rotation angle sensor 44 provided in the electric servo motor 12 and a power supply voltage signal from a voltage sensor 51 are also input.

  The control unit 6 controls the brake fluid pressure generated by the motor drive cylinder 13 based on the detection signal from the pedal position sensor 11a and in accordance with the running situation determined from the detection signals from the various sensors. Further, in the case of a hybrid vehicle (or an electric vehicle) that is a target vehicle of the present embodiment, regeneration control by a motor / generator is performed. In the control unit 6, the magnitude of regeneration when performing regeneration control is performed. The distribution control of the magnitude of the brake hydraulic pressure by the motor drive cylinder 13 is also performed.

  A control method during normal braking of the control unit 6 will be described. As shown in FIG. 2, in the initial state where the brake pedal 11 is not depressed, the on-off valves 24 a and 24 b and the simulator valve 24 c are open, and in the motor drive cylinder 13, the threaded rod 19 is most retracted. Accordingly, the pistons 21a and 21b urged by the return springs 27a and 27b are also retracted, and no brake fluid pressure is generated in the liquid chambers 23a and 23b.

  FIG. 4 is a control flow diagram executed in the control unit 6. This control flow is executed when the driver steps on the brake pedal 11 from the initial state (pedal position = 0). In step S1, it is determined whether or not the pedal position has reached a position P1 (start value). The range where the pedal position is from position 0 to position P1 is provided as pedal play, and position P1 may be set arbitrarily. The control unit 6 controls the on-off valves 24a and 24b and the motor drive cylinder 13 so as to supply hydraulic pressure to the wheel cylinders 2b and 3b when the pedal position becomes equal to or greater than the position P1. In step S1, if the determination is No, step S1 is repeated until the pedal position reaches position P1, and if the determination is Yes, the process proceeds to step S2.

  In step S2, the control unit 6 determines whether the power supply voltage is equal to or higher than the threshold voltage Vsh based on a signal corresponding to the power supply voltage from the voltage sensor 51. The threshold voltage Vsh is set as a lower limit value of the power supply voltage that can secure a sufficient voltage to close the on-off valves 24a and 24b even if the electric servo motor 12 and the on-off valves 24a and 24b are started simultaneously. Is done. Here, regarding the voltage supplied to the on-off valves 24a and 24b, a voltage that can reliably operate the on-off valves 24a and 24b is set as a start guarantee voltage (see the one-dot chain line in FIGS. 5 and 6), and the on-off valve 24a A voltage that can reliably maintain 24b in the closed state is a retention guarantee voltage (see the two-dot chain line in FIGS. 5 and 6). In the closed state, the on-off valves 24a and 24b according to the present embodiment receive the hydraulic pressure from the motor drive cylinder 13 and the valve body 58 is urged toward the valve seat 57 side. Lower. When the electric servo motor 12 is activated (starts driving), a large activation current flows and the power supply voltage temporarily decreases greatly. The threshold voltage Vsh is the voltage supplied to the on / off valves 24a and 24b even when the electric servo motor 12 and the on / off valves 24a and 24b start to operate simultaneously. It is set to a value that does not drop below the guaranteed startup voltage.

  When the determination in step S2 is Yes, the process proceeds to step S3, and the control unit 6 operates the on-off valves 24a and 24b in the closing direction and normally operates the motor drive cylinder 13 (electric servo motor 12). In the normal operation by the control unit 6 here, the target motor rotation angle of the electric servo motor 12 is set based on the pedal position, and the electric servo motor 12 is controlled by feedback control so that the actual motor rotation angle matches the target motor rotation angle. Drive. The target motor rotation angle based on the pedal position is set based on a predetermined normal operation map. In the normal operation map, for example, the target motor rotation angle may increase as the pedal position increases. By driving the electric servo motor 12, the threaded rod 19 and the first piston 21a are pushed out, and hydraulic pressure is generated in the first liquid chamber 23a.

  When the determination in step S2 is No, the process proceeds to step S4, and the control unit 6 operates the on-off valve in the closing direction and operates the motor drive cylinder 13 (electric servo motor 12) with low power consumption. In the low power consumption operation by the control unit 6 here, the target motor rotation angle of the electric servo motor 12 is set based on the pedal position as in the normal operation, and the actual motor rotation angle matches the target motor rotation angle. Thus, the electric servo motor 12 is driven by feedback control, but the target motor rotation angle set based on the pedal position is set smaller than the target motor rotation angle set by normal operation. That is, for the same pedal position, the operation amount of the motor drive cylinder 13 is controlled to be smaller in the low power consumption operation than in the normal operation. The target motor rotation angle based on the pedal position in the low power consumption operation may be set based on a predetermined low power consumption operation map, or a predetermined coefficient is set to the target motor rotation angle set based on the normal operation map. You may set by multiplying. In the low power consumption operation, the drive amount of the electric servo motor 12 is smaller than that in the normal operation, so that the electric servo motor 12 is driven with a lower duty ratio than in the normal operation, and the starting current of the electric servo motor 12 is reduced. By driving the electric servo motor 12, the threaded rod 19 and the first piston 21a are pushed out, and hydraulic pressure is generated in the first liquid chamber 23a.

  After step S4, in step S5, it is determined whether or not the motor rotation angle has reached a predetermined determination value θsh. The determination value θsh is a period required for the motor rotation angle to reach the determination value θsh from the initial value when the electric servo motor is driven with low power consumption operation, and a period required for completing the closing operation of the on-off valves 24a and 24b. It is set to be longer than (valve closing operation period). That is, when the closing operation of the on-off valves 24a and 24b and the drive of the electric servo motor 12 are started simultaneously, the motor rotation angle reaches the determination value θsh after the closing operation of the on-off valves 24a and 24b is completed. Is set. In Step S5, when the determination is No, Step S5 is repeated until the motor rotation angle reaches the determination value θsh, and when the determination is Yes, the process proceeds to Step S6.

  In step S6, the control unit 6 normally operates the motor drive cylinder 13 (electric servo motor 12).

  The effect when the control is performed according to the above control flow will be described with reference to the time charts of FIGS. FIG. 5 shows a case where the determination in step S2 (whether the power supply voltage is equal to or higher than the threshold voltage Vsh) is Yes, and FIG. 6 shows a case where the determination in step S2 is No.

  As shown in FIG. 5, when the driver depresses the brake pedal 11 from time 0 and the pedal position detected by the pedal position sensor 11a becomes the position P1 (time t1), the control unit 6 has a power supply voltage of the threshold value. It is determined whether or not the voltage is Vsh or higher, the power supply voltage is determined to be higher than or equal to the threshold voltage Vsh, and the on-off valves 24a and 24b are closed and the motor drive cylinder 13 (electric servo motor 12) is normally operated. Let

  When the electric servo motor 12 is normally operated, a large starting current flows through the electric servo motor 12 at the time of starting, and the voltage supplied to the on-off valves 24a and 24b decreases from the initial value Vv0 to Vv1, but the power supply voltage is the threshold voltage. Since it is Vsh, the voltage value Vv1 supplied to the on-off valves 24a and 24b is maintained at or above the guaranteed start-up voltage. Therefore, the on / off valves 24a and 24b are reliably closed.

  On the other hand, when it is determined whether or not the power supply voltage is equal to or higher than the threshold voltage Vsh when the pedal position is at the position P1 (time t1), when it is determined that the power supply voltage is lower than the threshold voltage Vsh, FIG. As shown, the on-off valves 24a and 24b are closed, and the motor drive cylinder 13 (electric servo motor 12) is operated with low power consumption. In the low power consumption operation, since the operation amount of the electric servo motor is smaller than that in the normal operation, the activation power generated in the electric servo motor 12 at the time of activation is small, and the voltage supplied to the on-off valves 24a and 24b maintains the initial value Vv0. To do. Therefore, the on-off valves 24a and 24b are reliably closed.

  At time t3 after the closing operation of the on-off valves 24a and 24b is completed, the motor rotation angle reaches the determination value θsh, and the control unit 6 operates the motor drive cylinder 13 (electric servo motor 12) as a low power consumption operation. To normal operation. As a result, a large starting current flows through the electric servo motor 12, and the voltage supplied to the on-off valves 24a and 24b decreases from the initial value Vv0 to Vv2 and becomes smaller than the guaranteed start-up voltage, but the on-off valves 24a and 24b are closed. Since the operation has already been completed, the open / close valves 24a and 24b can maintain the closed state if the retention guarantee voltage is maintained.

  In the present embodiment, as described above, when the power supply voltage is smaller than the threshold voltage Vsh, the voltage supplied to the on-off valves 24a and 24b is set to be equal to or higher than the startup guarantee voltage by reducing the startup current of the electric servo motor 12. As a result, the on-off valves 24a and 24b can be reliably closed. Since this control is performed only when the power supply voltage is smaller than the threshold voltage Vsh, when the power supply voltage is equal to or higher than the threshold voltage Vsh, the electric servo motor 12 is normally operated and the motor drive cylinder 13 is quickly liquidated. Pressure can be generated.

  As a modification of the above embodiment, as shown in the control flow diagram of FIG. 7, when it is determined in step S12 that the power supply voltage is smaller than the threshold voltage Vsh, the on / off valves 24a and 24b are switched in step S14. Only the valve closing operation is performed. In the subsequent step S15, it is determined whether or not the time from when the pedal position has reached P1 has reached a predetermined determination time Tsh, and if the time has reached the determination time Tsh, the motor is driven. The cylinder 13 may be normally operated. The determination time Tsh is set to be longer than the time required for the on-off valves 24a and 24b to complete the valve closing operation (valve closing operation period). As described above, when the power supply voltage is smaller than the threshold voltage Vsh, only the closing operation of the on-off valves 24a and 24b is performed first, and after the closing operation of the on-off valves 24a and 24b is completed, the motor drive cylinder 13 is turned on. You may make it operate normally.

  DESCRIPTION OF SYMBOLS 1 ... Brake device, 2b * 3b ... Wheel cylinder, 6 ... Control unit (control means), 8 ... Brake hydraulic pressure generator, 11 ... Brake pedal, 11a ... Pedal position sensor (pedal operation amount detection means), 12 ... Electricity Servo motor, 13 ... motor drive cylinder (hydraulic pressure generating means), 15 ... master cylinder, 17a ... first liquid chamber, 17b ... second liquid chamber, 23a ... first liquid chamber, 23b ... second liquid chamber, 24a 24b ... Open / close valve, 24c ... Simulator valve, 25a ... Master cylinder side brake pressure sensor, 25b ... Motor driven cylinder side brake pressure sensor, 26 ... VSA device, 28 ... Simulator (reaction force simulator), 42a, 42b ... Piping (oil) Path), 43a, 43b ... piping, 44 ... motor rotation angle sensor (operation amount detection means), 51 ... voltage sensor

Claims (4)

A master cylinder that is mechanically coupled to the brake pedal and generates hydraulic pressure;
A wheel cylinder connected to the master cylinder via an oil passage;
An on-off valve that is an electromagnetic valve provided on the oil passage;
Pedal operation amount detection means for detecting a pedal operation amount corresponding to the operation amount of the brake pedal;
Hydraulic pressure generating means connected between the on-off valve of the oil passage and the wheel cylinder, and supplying hydraulic pressure to the oil passage by driving of an electric motor;
A power source for supplying power to the on-off valve and the electric motor;
A vehicle brake device having control means for controlling the on-off valve and the electric motor in accordance with the pedal operation amount;
The control means drives the valve to close the on-off valve when the pedal operation amount reaches a start value at which supply of hydraulic pressure from the hydraulic pressure generating means to the wheel cylinder should be started, and In the valve closing operation period required from when the start value is reached until the on-off valve is closed, the power consumption of the electric motor is suppressed so that a voltage sufficient to close the on-off valve can be secured. A vehicle brake device. Voltage detecting means for detecting the voltage of the power source;
The control means drives to close the on-off valve when the voltage of the power source becomes a predetermined threshold voltage or less and the pedal operation amount reaches the start value, and the valve closing operation period is The vehicle brake device according to claim 1, wherein power consumption of the electric motor is suppressed so that a voltage sufficient to close the on-off valve can be secured. An operation amount detecting means for detecting an operation amount of the fluid pressure generating means;
The on-off valve is configured to be urged toward the closed position by the pressure from the hydraulic pressure generating means in the closed state,
The control means determines whether or not the on-off valve is in a closed state based on an operating amount of the hydraulic pressure generating means after the pedal operation amount reaches the start value, and generates the hydraulic pressure. 3. The method according to claim 1, wherein when the operation amount of the means becomes equal to or greater than a value corresponding to the closed state of the on-off valve, the energization amount to the on-off valve is reduced from that during the valve closing operation. The vehicle brake device described in 1.   The said control means makes the operating speed of the said hydraulic pressure generation means smaller than the operating speed in periods other than the said valve operating period in the said valve closing operation period. The vehicle brake device according to any one of the items.

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