JP2012206572A - Vehicular brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular brake device that can achieve a larger heat generation reduction effect of a solenoid valve.SOLUTION: A solenoid valve is provided on an oil passage between a master cylinder and a wheel cylinder, and a motor drive cylinder for generating brake hydraulic pressure is provided between the solenoid valve and a wheel cylinder, so that energization is controlled to close the solenoid valve during braking. Piping is implemented so that the hydraulic pressure by the master cylinder may work on in the valve opening direction of the solenoid valve and so that hydraulic pressure by hydraulic pressure generating means may work on in the valve closing direction. The magnitude of energization to the solenoid valve is controlled so that a valve closing state of the solenoid valve may be maintained on the basis of operation amount and travel of the hydraulic pressure generating means. According to a difference in the magnitude of hydraulic pressure between master cylinder side and hydraulic pressure generating side, a driving force of the solenoid valve in the valve closing direction can be estimated. Thus, minimum energization required to maintain a valve closing state can be implemented, thereby achieving further reduction in heat generation of the solenoid valve.

Description

  The present invention relates to a vehicle brake device, and more particularly to a brake generating device that generates a braking force by a brake-by-wire, and includes a hydraulic pressure generating means for generating a hydraulic pressure for a wheel cylinder, a master cylinder, a hydraulic pressure generating means, The present invention relates to a vehicle brake device provided with an electromagnetic valve that opens and closes between the two.

  In a vehicular brake device that performs braking force of a vehicle by brake-by-wire, a motor drive cylinder and a wheel cylinder as hydraulic pressure generating means are provided separately from a master cylinder mechanically connected to an operation member (brake pedal). And a master cylinder and a wheel cylinder are connected as a fail safe. A solenoid valve that is normally open is provided on the pipe between the master cylinder and the wheel cylinder, the solenoid valve is closed during normal braking, and the motor drive cylinder is operated to generate brake fluid pressure.

  In such a vehicle brake device, in order to suppress the heat generation of the solenoid valve due to the energized state for maintaining the valve closed state, the valve opening pressure of the solenoid valve depends on the hydraulic pressure of the motor drive cylinder. There is one in which the solenoid valve is energized so as to be equal to or higher than the hydraulic pressure (see, for example, Patent Document 1).

Japanese Patent No. 4313731

  In the electromagnetic valve as described above, a return spring that biases in the valve opening direction is known. In that case, a current sufficient to operate the valve body against the spring biasing force when the valve is closed. In addition, it is necessary to continue the flow of the current necessary for maintaining the valve closed state. When the solenoid valve is provided so that the hydraulic pressure from the master cylinder is applied in the valve opening direction and the hydraulic pressure from the motor drive cylinder is applied in the valve closing direction, the electromagnetic The driving force of the valve needs to be more than the driving force that resists the hydraulic pressure from the master cylinder.

  Some brake devices provided with such a brake-by-wire system perform regenerative cooperative control. In this case, since the hydraulic pressure of the master cylinder is determined according to the pedal stroke of the brake pedal, the regenerative cooperative control reduces the amount of operation of the motor-driven cylinder according to the magnitude of regenerative braking. The hydraulic pressure on the cylinder side decreases. On the other hand, since the hydraulic pressure of the master cylinder does not change in a state where the amount of depression of the brake pedal is constant under regenerative cooperative control, the force (hydraulic pressure) in the valve opening direction of the solenoid valve becomes relatively large.

  To cope with the case where the hydraulic pressure on the master cylinder side becomes relatively large as described above, it is conceivable to set a large current for maintaining the closed state of the solenoid valve. If the pedal stroke does not reach the full stroke (the fluid pressure on the master cylinder side is small), the current will flow more than necessary for the valve closing maintenance current, and the heat reduction effect of the solenoid valve will be reduced. There is a problem.

  In order to solve such a problem and realize a greater effect of reducing the heat generation of the solenoid valve, in the present invention, it is mechanically connected to the operating member (11) to generate a hydraulic pressure. A master cylinder (15), a wheel cylinder (2b, 3b) connected to the master cylinder via oil passages (42a, 42b, 43a, 43b), and a normally open solenoid valve provided on the oil passage (24a, 24b), an operation amount detection means (11a) for detecting an operation amount of the operation member, and connected between the solenoid valve and the wheel cylinder in the oil passage, and detected by the operation amount detection means A vehicle pressure generating means (13) for supplying a hydraulic pressure to the oil passage according to a value, and a control means (6) for controlling the electromagnetic valve and the hydraulic pressure generating means according to the operation amount. Brake device, front The solenoid valve is configured such that the hydraulic pressure by the master cylinder acts in the valve opening direction, and the hydraulic pressure by the hydraulic pressure generating means acts in the valve closing direction, and the control means has the operation amount and the hydraulic pressure. Based on the operation amount of the generating means, the magnitude of energization to the solenoid valve is controlled so that the closed state of the solenoid valve is maintained.

  According to this, since the energization to the solenoid valve is controlled based not only on the operation amount of the brake pedal as the operation member but also on the operation amount of the motor drive cylinder as the hydraulic pressure generating means, for example, the master cylinder side The drive force in the valve closing direction of the solenoid valve can be estimated according to the difference in hydraulic pressure between the motor and the cylinder that drives the motor, and the minimum energization necessary to maintain the valve closed state accordingly. It can be performed.

  In particular, the control means (6) preferably includes energization fixing means (32) for fixing the magnitude of energization when the manipulated variable reaches an upper limit value. According to this, in the state where the brake pedal as the upper limit value of the operation amount has reached the full stroke, it is not possible to detect an increase in the hydraulic pressure on the master cylinder side with an increase in the further depression force. The valve closed state can be reliably maintained by fixing to the magnitude of energization.

  In addition, a valve-opening direction driving force setting unit (34) that sets a driving force in the valve-opening direction of the electromagnetic valve according to the operation amount, and driving of the electromagnetic valve in the valve-closing direction according to the operation amount A valve closing direction driving force setting unit (37) for setting a force, and the control means energizes the solenoid valve when the driving force in the valve closing direction exceeds the driving force in the valve opening direction. Should be reduced. According to this, the magnitude of the valve closing direction driving force of the solenoid valve can be obtained according to the comparison between the valve closing direction driving force and the valve opening direction driving force, and the solenoid valve is energized based on the result. By controlling, it is possible to cope with a case where the hydraulic pressure generating means fluctuates asynchronously with respect to the operation amount (for example, a state following the change in the regenerative amount during regenerative braking).

  Moreover, the said control means is good to reduce the electricity supply to the said solenoid valve in the range which can maintain the valve closing state of the said solenoid valve. According to this, since the maintenance of the valve closing state is ensured and the energization is reduced, it is possible to prevent the valve closing state from being unable to be maintained due to excessive reduction.

  As described above, according to the present invention, the driving force in the valve closing direction of the electromagnetic valve can be estimated according to the difference in hydraulic pressure between the master cylinder side and the hydraulic pressure generating means side, and accordingly Since the minimum necessary energization for maintaining the closed state can be performed, the heat generation of the electromagnetic valve can be further reduced.

It is a principal part systematic diagram of the brake system of the motor vehicle to which this invention was applied. 1 is a hydraulic circuit diagram schematically showing a brake device for an automobile to which the present invention is applied. It is a principal part circuit block diagram which shows the control point based on this invention. It is sectional drawing which shows typically the solenoid valve to which this invention was applied. It is a figure which shows the relationship between a pedal stroke and a hydraulic pressure. It is a figure which shows the hydraulic pressure change with respect to a stroke. It is a figure which shows the electric current change which supplies with electricity to a solenoid valve according to a stroke.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of a principal 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 1 and a pair of left and right rear wheels 3 disposed on the rear side of the vehicle 1. A motor / generator 5 is connected to the front wheel axle 4 connected to the left and right front wheels 2 in a torque transmission relationship. 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.

  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. 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 having a disc 2a, 3a and a wheel cylinder 2b, 3b integrated with the wheel (front wheel 2, rear wheel 3) 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 that constitutes a braking force generating means via a known brake pipe as an oil passage. 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.

  Further, the front wheel 2 and the rear wheel 3 are provided with respective wheel speed sensors 9 for detecting the respective wheel speeds, and the brake pedal 11 serves as an operation amount detecting means for detecting a brake operation amount that is a depression amount by the driver. Displacement sensor 11a is provided. Each detection signal of each wheel speed sensor 9 and displacement sensor 11 a is input to the control unit 6.

  When the control unit 6 determines that a braking command has been generated based on the output signal of the displacement sensor 11a of the brake pedal 11, the control unit 6 performs control to generate a braking force. In the illustrated example, regenerative cooperative control combining regenerative braking and hydraulic braking can be performed.

  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 displacement amount) of the brake pedal 11 is detected by the displacement sensor 11a, and the motor drive cylinder 13 serving as the hydraulic pressure generating means is driven based on the detected value to generate the brake hydraulic pressure. Is generated. 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.

  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. In the cylinder of the master cylinder 15, a first liquid chamber 17a is formed between the first piston 15a and the second piston 15b, and the second liquid is disposed on the side opposite to the first piston of the second piston 15b. A 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 hydraulic pressure generating chamber 23a is formed between the first piston 21a and the second piston 21b, and the second piston 21b is arranged on the side opposite to the first piston 21a. A two-hydraulic pressure generating chamber 23b is formed.

  The first fluid chamber 17a of the master cylinder 15 is connected to the first fluid pressure generating chamber 23a via the respective pipelines 42a and 42b constituting the oil passage, and the second fluid chamber 17b of the master cylinder 15 similarly constitutes the oil passage. Are connected to the second hydraulic pressure generating chamber 23b through the respective pipelines 43a and 43b. A normally-open electromagnetic valve 24a as a shutoff valve is provided on the oil passage (between 42a and 42b) composed of the conduits 42a and 42b, and on the oil passage (43a and 43b) which is also composed of the conduits 43a and 43b. A normally open solenoid valve 24b as a shut-off valve is also provided. With this piping, the first fluid chamber 17a communicates with the first fluid chamber 17a of the master cylinder 15 through the normally open electromagnetic valve 24a, and the second fluid chamber 23b. In addition, the second liquid chamber 17b of the master cylinder 15 communicates with the normally open electromagnetic valve 24b. A master cylinder side brake pressure sensor 25a is connected between the first fluid chamber 17a and the electromagnetic valve 24a, and a motor driven cylinder side brake pressure sensor is connected between the electromagnetic valve 24b and the second fluid pressure generating chamber 23b. 25b is connected.

  Further, a cylinder type simulator 28 is connected between the second liquid chamber 17b and the electromagnetic valve 24b via a normally closed type electromagnetic valve 24c. The simulator 28 is provided with a piston 28a that divides the inside of the cylinder, a liquid storage chamber 28b is formed on the solenoid 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 28a side. A spring 28c is received. When both the solenoid valves 24a and 24b are closed and the solenoid valve 24c is opened, the second fluid chamber 17b and the fluid storage chamber 28b communicate with each other. When the brake pedal 11 is depressed in this state, the brake in the second fluid 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.

  Furthermore, the first hydraulic pressure generation chamber 23a and the second hydraulic pressure generation chamber 23b of the motor drive cylinder 13 are plural (4 in the illustrated example) via the respective pipelines 42c and 43c and, for example, the VSA device 26 in the present embodiment. Are connected to the wheel cylinders 2b and 3b. 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. In the VSA device 26, each brake actuator 26b using various hydraulic elements respectively constituting a first system corresponding to each wheel cylinder 2b of the front wheel and a second system corresponding to each wheel cylinder 3b of the rear wheel. And a VSA control unit 26a for controlling them.

  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 stroke 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. Further, a motor rotation angle signal of the electric servo motor 12 is also input.

  The control unit 6 controls the brake hydraulic pressure generated by the motor drive cylinder 13 based on the detection signal from the stroke 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, and the control unit 6 performs regeneration in the case of performing regeneration control. The distribution control of the magnitude of the brake hydraulic pressure by the motor drive cylinder 13 is also performed.

  Next, an example of the valve control circuit according to the present invention will be described with reference to the block diagram of FIG. The circuit of FIG. 3 may be provided in the control unit 6 or may be processed in combination with a program.

  In the figure, a stroke Sp, which is a detected value of the brake pedal 11 by the stroke sensor 11a, is inputted to the maximum value discriminating unit 31. In the maximum value discriminating unit 31, whether the stroke Sp exceeds the maximum value Spf (Sp> Spf) Determine whether or not. When the brake pedal 11 is depressed and both the solenoid valves 24a and 24b are closed and the piston 28a of the simulator 28 bottoms out, the brake fluid is sealed between the master cylinder 15 and the simulator 28. Then, the stroke Sp reaches a limit value (Spf + ΔSp) that exceeds the maximum control value Spf.

  When the stroke Sp exceeds the maximum control value Spf, the maximum value discriminating unit 31 outputs a limit value (Spf + ΔSp) to the constant output unit 32 as the energization fixing means. At the limit of the stroke Sp, the hydraulic pressure on the motor drive cylinder 13 side (pressure of the brake pressure sensor 25b) is constant unless regenerative cooperative braking is performed, but the brake pressure on the master cylinder 15 side (pressure of the brake pressure sensor 25a) ) Increases with an increase in the depressing force of the brake pedal 11, the brake pressure on the master cylinder 15 side cannot be estimated from the stroke Sp. In this case, the constant output unit 32 outputs a predetermined value Id, which is a value sufficient to ensure the hydraulic sealing performance of the electromagnetic valves 24a and 24b. The predetermined value Id output from the constant output unit 32 is input to one of the two inputs of the OR circuit 33.

  When the stroke Sp is equal to or less than the maximum value Spf, the value (stroke Sp) detected by the stroke sensor 11a is input to the valve opening current setting unit 34 as the valve opening direction driving force setting unit. The valve opening current setting unit 34 obtains the valve opening direction current Io of the electromagnetic valves 24a and 24b corresponding to the magnitude of the stroke Sp. For example, a stroke-valve opening current conversion map in which the valve opening direction current Io changes proportionally to the stroke Sp (Io = a × Sp: a is a coefficient) can be used. The output (valve opening direction current Io) of the valve opening current setting unit 34 is input to the subtractor 35 as a subtraction value.

  On the other hand, the motor rotation angle θ signal of the electric servo motor 12 is input to the motor drive cylinder stroke setting unit 36, and the motor drive cylinder stroke setting unit 36 corresponds to the magnitude of the motor rotation angle θ. The cylinder stroke amount Sm is obtained. The cylinder stroke amount Sm is set using a motor rotation angle-stroke conversion map in which the cylinder stroke amount Sm changes proportionally to the motor rotation angle θ (Sm = b × θ: b is a coefficient), as described above. be able to. The output (cylinder stroke amount Sm) of the motor drive cylinder stroke setting unit 36 is input to a valve closing current setting unit 37 serving as a valve closing direction driving force setting unit.

  The valve closing current setting unit 37 obtains the valve closing direction current Ic of the electromagnetic valves 24a and 24b corresponding to the magnitude of the cylinder stroke amount Sm. Similarly to the above, a stroke-valve closing current conversion map in which the valve closing direction current Ic changes in proportion to the cylinder stroke amount Sm (Ic = c × Sm: c is a coefficient) can be used. The output (valve closing direction current Ic) of the valve closing current setting unit 37 is input to the subtractor 35 as an added value. The valve closing direction current Ic is a corresponding amount when a similar valve closing force is generated by the electromagnetic valves 24a and 24b.

  The subtractor 35 outputs a deviation ΔI (= Io−Ic) obtained by subtracting the valve closing direction current Ic from the valve opening direction current Io to the valve closing maintenance auxiliary current setting unit 38. The valve closing maintenance auxiliary current setting unit 38 obtains a valve closing maintenance auxiliary current Is that is a thrust current corresponding to the auxiliary force for maintaining the closed state of the electromagnetic valves 24a and 24b based on the deviation ΔI. The valve closing maintenance auxiliary current Is changes proportionally to the deviation ΔI (Is = d × ΔdI: d is a coefficient). However, when the deviation ΔI is small, it becomes a certain lower limit, and when the deviation ΔI is large. It is obtained using a deviation-thrust current conversion map set so as to have a certain upper limit value. The output of the valve closing maintenance auxiliary current setting unit 38 (valve closing maintenance auxiliary current Is) is input to the other of the two inputs of the OR circuit 33.

  As for the output of the OR circuit 33, the larger one of the valve closing maintenance auxiliary current Is and the predetermined value Id of the constant output unit 32 is input to the subtracter 39 as a subtraction value. To the subtractor 39, the valve closing maintaining current Ik in which the power output Wb is set via the limiting gain circuit 40 is input as an added value. The result of the subtracter 39 is output as a control value Si for the amount of current applied to the solenoid valves 24a and 24b to a valve drive circuit (not shown) that controls the drive of the solenoid valves 24a and 24b.

  Here, an example of the electromagnetic valves 24a and 24b will be described with reference to FIG. As shown in FIG. 4, each of the electromagnetic valves 24 a and 24 b can be seated on a casing 56 in which a passage 55 communicating with the pipe 42 a is formed, a valve seat 57 provided in the middle of the passage 55, and the valve seat 57. A valve body 58, a columnar plunger 59 connected to the valve body 58, a solenoid 60 provided in the casing 56, and a direction in which the plunger 59 is retracted to move the plunger 59 forward and backward by magnetic force. And a coil spring 61 for urging the spring.

  In addition, the power of the battery 7 is supplied to the solenoid 60. When the solenoid 60 is not energized, the plunger 59 is retracted from the valve seat 57 by the coil spring 61, the valve body 58 is separated from the valve seat 57, the passage 55 is opened, and both the pipe lines 42 a. 42b communicates. 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, the valve body 58 is seated on the valve seat 57, the passage 55 is closed, and both pipes are closed. The paths 42a and 42b are blocked.

  When the solenoid valve 24 a is closed with the valve body 58 seated on the valve seat 57, the valve body 58 is urged toward the valve seat 57 by receiving the hydraulic pressure from the motor drive cylinder 13. The solenoid valve 24b has the same configuration as the solenoid valve 24a.

  Next, an opening / closing control procedure of the electromagnetic valves 24a and 24b in the vehicle brake device of the present invention configured as described above will be described.

  FIG. 5 shows changes in the fluid pressure (solid line) in the first fluid chamber 17a and the fluid pressure (two-dot chain line) in the second fluid chamber 17b, which are the master cylinder fluid pressure, with respect to the pedal stroke Sp of the brake pedal 11. It is a figure which shows the change of the cylinder pressure Sm of the motor drive cylinder 13, the brake hydraulic pressure which generate | occur | produces with the motor drive cylinder 13, and the differential pressure | voltage of a master cylinder hydraulic pressure and a brake hydraulic pressure.

  As shown in the figure, until the pedal stroke Sp reaches a full stroke, the cylinder stroke Sm also changes so as to be proportional to the change in the stroke. However, if the cylinder stroke Sm is only based on the displacement sensor 11a, the pedal stroke When Sp reaches full stroke, it becomes a constant value. On the other hand, the brake pedal 11 does not increase the stroke when the flow of the brake fluid between the master cylinder 15 and the simulator 28 stops, but even in that case, the hydraulic pressure (second fluid chamber is increased by increasing the stepping force. 17b) can rise (solid line in the figure).

  Note that the stroke change of the motor drive cylinder 13 decreases as indicated by a two-dot chain line in the figure in accordance with the braking distribution when the regenerative cooperative control is performed, for example, when the solid line in the figure is the maximum value. In that case, the brake fluid pressure also decreases.

  Moreover, with reference to FIG. 6, an example of the change of each hydraulic pressure with respect to the depression change of the brake pedal 11 and a differential pressure is demonstrated. As the pedal stroke Sp rises to the full stroke, the brake fluid pressure generated by the motor drive cylinder 13 (solid line), the fluid pressure generated by the first fluid chamber 17a (two-dot chain line), and the second fluid chamber The hydraulic pressure (dotted line) generated at 17b increases. In addition, the liquid pressure of the first liquid chamber 17a and the second liquid chamber 17b is the same.

  In FIG. 6, an example of the depression operation of the pedal stroke 11 is shown as a change with time, and the change in the master cylinder hydraulic pressure and the brake hydraulic pressure according to the change, and the differential pressure between them The change in pressure difference is shown. The fluid pressure in the first fluid chamber 17a is indicated by a one-dot chain line, the fluid pressure in the second fluid chamber 17b is indicated by a two-dot chain line, and the brake fluid pressure by the motor drive cylinder 13 is indicated by a solid line. Further, as shown in the figure, in the brake device in the brake-by-wire to which the present invention is applied, the hydraulic pressure (13) by the motor drive cylinder 13 is higher than the hydraulic pressure (17b) by the master cylinder 15. Designed to be

  In the figure, the pedal stroke Sp is shown in the full stroke state and the stepping force increases. In this case, even if it is detected that the pedal stroke Sp is constant, the master cylinder hydraulic pressure (17b) increases as indicated by the one-dot chain line. Then, as the pedal stroke Sp is reduced by releasing the stepping force with the passage of time, the fluid pressure in the second fluid chamber 17b decreases, and after the fluid pressure in the first fluid chamber 17a becomes the same, the same pressure is reached. And decreases with a decrease in the pedal stroke Sp. When each hydraulic pressure changes in this way, the differential pressure (the pressure difference applied to both sides of the valve body 58 of the electromagnetic valves 24a and 24b) changes as shown in the figure.

  Next, a procedure for energizing the solenoid valves 24a and 24b when the fluid pressure in the second fluid chamber 17b increases in the full stroke state will be described with reference to FIG. Here, as the waveform of the solenoid valve current, the current corresponding to the valve closing direction driving force necessary for closing the solenoid valves 24a and 24b is shown as "valve closing direction" (solid line), and the valve opened state Current to be shown is shown as “valve opening direction” (two-dot chain line) In the figure, the reason why the waveform of the “valve opening direction” is not shown in the full stroke region is that the current corresponding to the valve opening direction cannot be defined.

  Then, the applied current for driving the electromagnetic valves 24a and 24b in the valve closing direction is controlled as indicated by the two-dot chain line at the bottom of FIG. At the bottom of the figure, Iv is the solenoid valve drive current (rated value), and Id is the brake pressure> master cylinder hydraulic pressure, as described above, with respect to the deceleration generated in the full stroke. Is a predetermined value that can be maintained. As described above, when the depression force is increased as described above with the full stroke of the brake pedal 11, the hydraulic pressure by the master cylinder 15 increases and the force for driving the valve body 58 in the valve opening direction increases. A current of a predetermined value Id that can generate a driving force in the valve closing direction that resists is supplied, and the closed state of the electromagnetic valves 24a and 24b is reliably maintained. In addition, when the depression of the brake pedal 11 is maintained, the motor drive cylinder 13 may fluctuate due to factors other than the stroke of the brake pedal 11 (cooperative regenerative braking), so that the solenoid valves 24a and 24b are kept closed. A constant current is preferable.

  Except for the full stroke, the applied current is controlled in accordance with the pedal stroke Sp and the cylinder stroke amount Sm as shown by the two-dot chain line in FIG. 7, thereby reducing the current with respect to the rated value Iv of the solenoid valves 24a and 24b. Can be reduced as shown by the solid line in the figure. Thereby, the heat_generation | fever by continuing flowing rated value Iv to electromagnetic valve 24a * 24b can be reduced. In addition, the power saving effect is increased.

2b, 3b Wheel cylinder 6 Control means 11 Brake pedal (operation member)
11a Displacement sensor (operation amount detection means)
13 Motor driven cylinder (hydraulic pressure generating means)
15 Master cylinders 24a and 24b Solenoid valve 32 Constant output part
34 Valve opening current setting part (valve opening direction driving force setting part)
37 Valve closing current setting part (valve closing direction driving force setting part)
42a, 42b, 43a, 43b Piping (oil passage)

Claims (4)

A master cylinder mechanically connected to the operating member and generating hydraulic pressure;
A wheel cylinder connected to the master cylinder via an oil passage;
A normally open solenoid valve provided on the oil passage;
An operation amount detection means for detecting an operation amount of the operation member;
Hydraulic pressure generating means connected between the solenoid valve of the oil passage and the wheel cylinder, and supplying hydraulic pressure to the oil passage according to a detection value of the operation amount detection means;
A vehicular brake device having control means for controlling the electromagnetic valve and the hydraulic pressure generating means in accordance with the operation amount;
The solenoid valve is configured such that the hydraulic pressure by the master cylinder acts in the valve opening direction, and the hydraulic pressure by the hydraulic pressure generating means acts in the valve closing direction,
The control means controls the magnitude of energization to the electromagnetic valve so that the closed state of the electromagnetic valve is maintained based on the operation amount and the operation amount of the hydraulic pressure generating means. Brake device for vehicles.   2. The vehicle brake device according to claim 1, wherein the control unit includes an energization fixing unit that fixes the magnitude of the energization when the operation amount reaches an upper limit value. 3. A valve opening direction driving force setting unit that sets the driving force of the solenoid valve in the valve opening direction according to the operation amount, and a valve closing direction that sets the driving force of the solenoid valve in the valve closing direction according to the operation amount. A valve direction driving force setting unit,
The vehicle according to claim 1, wherein the control unit reduces energization to the electromagnetic valve when the driving force in the valve closing direction exceeds the driving force in the valve opening direction. Brake device.   4. The vehicle brake device according to claim 3, wherein the control unit reduces energization to the solenoid valve within a range in which the solenoid valve can be kept closed.

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