JP2012206571A - Vehicular brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress operational noise during switching a solenoid valve in a vehicular brake system.SOLUTION: When a brake pedal is operated and a pedal stroke reaches a predetermined value Sp1, a closing-valve driving voltage is set at Vc1 and the voltage is increased to Vc2 until the stroke reaches Sp2, according to a rise in the stroke. Application of a drive voltage is implemented not at a burst, but by including a state of a gradual change; therefore, the magnitude of operational noise by valve body's sitting can be reduced. During valve opening, the voltage is gradually reduced from Vc2 to Vc1, which is then reduced to 0V; therefore, the voltage returns to a valve closing state not at a burst, thereby suppressing operational noise from the valve body.

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.

  In the brake-by-wire, the piston of the hydraulic pressure generating cylinder is driven by an electric motor according to the stroke of the brake pedal, and the brake pedal and the hydraulic pressure generating cylinder are not mechanically connected. On the other hand, as a fail safe, a brake pedal as an operation member and a master cylinder are mechanically connected, and the master cylinder and the wheel cylinder are normally shut off by a shut-off valve provided between the master cylinder and the wheel cylinder. (See, for example, Patent Document 1).

JP 2009-29294 A

  Although it is suitable to use a solenoid valve as a shut-off valve in a hydraulic circuit such as the brake device described above, when controlling the solenoid valve to close when the brake pedal is depressed and to open when the brake pedal is released Whenever the solenoid valve is switched from opening to closing and from closing to opening, an operation sound is generated in which the valve body strikes the valve seat or the stopper. In particular, in a vehicle device, it is necessary to operate stably under various environmental conditions. Therefore, with a solenoid valve, setting the drive voltage to a high value tends to increase the above operating noise, which can be used as a sound insulation measure to reduce noise. There was a problem that costs increased.

  In order to solve such a problem and realize a vehicle brake device that can reduce the operation sound at the time of switching of the electromagnetic valve, in the present invention, it is mechanically connected to the operation member (11), A master cylinder (15) for generating hydraulic pressure, a wheel cylinder (2b, 3b) connected to the master cylinder via oil passages (42a, 42b), 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 the solenoid valve and the wheel cylinder of the oil passage, and depending on the operation amount, A vehicular brake device having a hydraulic pressure generating means (13) for supplying a brake hydraulic pressure to an oil passage and a control means (6) for controlling the electromagnetic valve and the hydraulic pressure generating means in accordance with the operation amount. The control means The electromagnetic valve is fully closed when the operation amount in the direction of generating the hydraulic pressure is detected, and the electromagnetic valve is fully opened when the operation amount leading to the disappearance of the hydraulic pressure is detected. In addition, when the solenoid valve is fully opened or fully closed, the drive voltage of the solenoid valve is changed, including a state where it is gradually changed.

  According to this, when, for example, a brake pedal as an operation member is operated and a brake hydraulic pressure is generated with respect to the wheel cylinder by a motor drive cylinder using, for example, a motor actuator as a hydraulic pressure generation means, the brake member is connected to the operation member. When the solenoid valve is fully closed to shut off the master cylinder and the wheel cylinder that generate hydraulic pressure, the drive voltage is applied not only at once, but also in a state of gradually changing. For this reason, it is possible to reduce the magnitude of the operation sound caused by the seating of the valve body.

  In particular, the control means (6) sets the energization control value for the solenoid valves (24a, 24b) so that the operation amount becomes a predetermined value or more and the brake fluid pressure by the hydraulic pressure generation means becomes a predetermined value or more. In this case, the electromagnetic valve may be reduced to a value that can maintain the closed state. According to this, when the brake hydraulic pressure on the hydraulic pressure generating means side becomes a predetermined value or more, the pressure difference between the solenoid valve and the master cylinder side becomes small, so that the solenoid valve can be kept closed. Power can be reduced.

  In addition, the control means (6) sets the energization control value for the solenoid valves (24a, 24b) to the operation amount and the operation amount of the hydraulic pressure generation means when the operation amount becomes a predetermined value or more. Control based on According to this, when the operation amount of the operation member is equal to or greater than a predetermined value and the closed state of the solenoid valve is ensured in the same manner as described above, energization to the solenoid valve is thereafter performed with the operation amount and the hydraulic pressure generation means corresponding thereto. The power consumption can be reduced by controlling the electromagnetic valve so that the closed state of the electromagnetic valve can be maintained based on the operation amount of the valve.

  Moreover, the said control means (6) is good to make the electricity supply control value to the said solenoid valve (24a * 24b) when the said operation amount becomes more than predetermined value into a fixed value lower than a maximum value. According to this, when the operation amount of the operation member is equal to or greater than a predetermined value and the closed state of the solenoid valve is ensured in the same manner as described above, the energization control value for the solenoid valve is thereafter set to a constant value lower than the maximum value. Thus, power consumption can be reduced.

  A plurality of the solenoid valves (24a, 24b) are provided, and the control means (6) may vary the timing of energization of the plurality of solenoid valves. According to this, since the generation timing of each operation sound of a plurality of solenoid valves is dispersed, it is possible to avoid the generation of a plurality of operation sounds at the same time, and to reduce the operation sounds of the plurality of solenoid valves as a whole.

  Moreover, the said control means (6) is good to reduce the electricity supply control value to the said solenoid valve (24a * 24b) according to time passage, when the said operation amount is less than predetermined value. According to this, even when the solenoid valve is changed from the fully closed state to the fully open state, the driving voltage is not lost at once, but is gradually reduced including the state of changing the operating voltage. Can be reduced.

  As described above, according to the present invention, when the solenoid valve is fully closed to shut off the master cylinder and the wheel cylinder that generate hydraulic pressure according to the operation amount of the operation member, the drive voltage is applied all at once. However, since it is applied including the state of changing gradually, the magnitude of the operating sound due to the seating of the valve body can be 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 flowchart which shows the control point based on this invention. (A) shows the drive voltage change at the time of valve closing, (b) is a figure which shows the drive voltage change at the time of valve opening. It is a figure corresponding to Fig.4 (a) which shows the 2nd example of the drive voltage change at the time of valve closing. It is a principal part circuit block diagram which shows the control point based on this invention. It is a figure which shows an example of the time chart based on this invention.

  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.

  The control unit 6 determines that a braking command has been issued when the output signal of the displacement sensor 11a of the brake pedal 11 is greater than 0, and 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 a piping 42a as an oil passage, and the second fluid chamber 17b of the master cylinder 15 is connected to the first fluid chamber 17a via a piping 42b as an oil passage. It is connected to the two fluid pressure generating chamber 23b. A normally open solenoid valve 24a as a shutoff valve is provided on the pipe 42a, and a normally open solenoid valve 24b as a shutoff valve is also provided on the pipe 42b. 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, a plurality (four in the illustrated example) of the first hydraulic pressure generation chamber 23a and the second hydraulic pressure generation chamber 23b of the motor drive cylinder 13 are respectively connected via the pipes 42a and 42b and, for example, the VSA device 26 in this embodiment. Are connected so as to communicate with 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, the control point based on this invention is demonstrated with reference to the flow of FIG. This control may be a program process using the CPU of the control unit 6. As shown in the figure, first, in step ST1, it is determined whether or not the brake pedal 11 has been released. If it is determined that the brake pedal 11 has not been released, the process proceeds to step ST2. The case where the brake pedal 11 is not released is a case where the brake pedal 11 is depressed, and the case where the brake pedal 11 is released is a case where the brake pedal 11 is released. For example, the brake pedal 11 may be returned to the standby position.

  In step ST2, a timer (not shown) is reset, and in the next step ST3, the valve closing drive voltage Vc is calculated. This valve closing drive voltage Vc may be obtained from a map associated with the pedal stroke Sp as shown in FIG. The valve closing drive voltage Vc according to the map is 0 until the pedal stroke Sp reaches 0 to Sp1, becomes Vc1 at Sp1, and increases proportionally from Vc1 to Vc2 in the region where the pedal stroke increases from Sp1 to Sp2. However, when the pedal stroke is Sp2 or more, Vc2 is constant. The pedal stroke Sp1 corresponds to the position where the first piston 15a closes the port 16c opening to the first liquid chamber 17a of the oil passage 16a communicating with the reservoir tank 16, and Sp2 is the second liquid chamber 17b of the oil passage 16b. Corresponding to the position where the second piston 15b closes the port 16d that opens to the rear. This pedal stroke Sp2 is a stroke corresponding to the start of increasing the brake pressure. The voltage Vc2 is a voltage that can close the solenoid valves 24a and 24b even at a high temperature, and the voltage Vc1 is a voltage that can be closed at room temperature (for example, 20 ° C.). In addition, when the hydraulic pressure of the master cylinder 15 acts in the valve opening direction of the electromagnetic valves 24a and 24b, it is preferable that the hydraulic pressure of the master cylinder 15 rises between the pedal strokes Sp1 and Sp2. Thereby, when the solenoid valves 24a and 24b are closed, the hydraulic pressure of the master cylinder 15 acts in the valve opening direction, so that the moving speed in the valve closing direction of the solenoid valves 24a and 24b is reduced, and the silencing effect at the time of sitting is achieved. Become big.

  On the other hand, if it is determined in step ST1 that the brake pedal 11 has been released, the process proceeds to step ST4. In step ST4, the timer is started to calculate the elapsed time, and in the next step ST5, the valve opening drive voltage Vo is calculated. This valve opening drive voltage Vo may be obtained from a map associated with the elapsed time of the timer as shown in FIG. The valve opening drive voltage Vo according to the map in the figure is constant at Vc2 from the start of the timer to time T1, and decreases from Vc2 to Vc1 in proportion to the passage of time from time T1 to time T2. It becomes 0 after time T2.

After step ST3 or step ST5, the process proceeds to step ST6, where it is determined whether or not the valve closing drive voltage Vc is equal to or higher than the valve opening drive voltage Vo. When the process proceeds to steps ST2 and ST3, the valve opening drive voltage Vo is Vc2 due to the timer reset, and the step is performed when the valve closing drive voltage Vc is less than the valve opening drive voltage Vo (= Vc2) as the pedal stroke Sp increases. Proceed to ST7. On the other hand, when the process proceeds to steps ST4 and ST5, the pedal stroke Sp decreases from Sp2 or more, but Vc is greater than Vo at the start of the timer calculation.
Proceed to step ST8. By setting the timer time T1 longer than the time for the brake pedal 11 to return to the standby position by the return spring, the valve opening drive voltage Vo obtained from FIG. Since it becomes larger than the valve closing drive voltage Vc (= 0), step ST8 can be continued.

  In step ST7, the valve driving voltage Ve is set as the valve closing driving voltage Vc, and the process proceeds to step ST9. In step ST8, the valve drive voltage Ve is set to the valve opening drive voltage Vo, and the process proceeds to step ST9. In step ST9, the solenoid valves 24a and 24b are driven and controlled by the valve drive voltage Ve, and this flow is finished.

  In the valve closing control of the electromagnetic valves 24a and 24b that shut off the master cylinder 15 and the wheel cylinders 2b and 3b, the conventional valve drive voltage is binary (0) as shown by the two-dot chain line in FIG. Vc2) was changed stepwise, and the seating sound of the valve body was large, resulting in noise.

  On the other hand, when the brake pedal 11 is depressed, the valve closing drive voltage Vc for closing the solenoid valves 24a and 24b from the opened state is 0 V as shown in FIG. 4A according to the increase in the pedal stroke Sp. Since it changes from the intermediate voltage Vc1 to gradually increase to the voltage Vc2 instead of increasing to the maximum voltage Vc2 at once, the seating noise of the valve body on the valve seat can be reduced. it can. The voltage Vc1 may be set to a voltage that can be closed at room temperature, for example, and the voltage Vc2 may be set to a voltage that can be closed even at a high temperature (assumed temperature in the use range of the vehicle).

  Further, as shown in FIG. 4B, when the brake pedal 11 is released from the depressed state, the valve opening drive voltage Vo for opening the electromagnetic valves 24a and 24b from the closed state is the time T1 measured by the timer. Rather than decreasing from the maximum voltage Vc2 to 0V all at once as shown by the two-dot chain line, it decreases from time T1, gradually decreases to the intermediate voltage Vc1 at time T2, and then changes to 0V. To do. At this time, the stroke of the motor drive cylinder 13 may be gradually decreased in synchronization with the decrease in the valve opening direction voltage Vo. Since the hydraulic pressure of the motor drive cylinder 13 acts in the valve closing direction, it is possible to reduce the sound during valve opening.

  Also in this case, in the valve opening control of the electromagnetic valves 24a and 24b, in the conventional control, the valve driving voltage is changed from Vc2 to 0V at a stroke as shown by the two-dot chain line in FIG. The impulsive sound hitting the stopper on the valve opening position side of the valve body was loud, and the operating noise was noise. On the other hand, according to the present invention, the valve opening drive voltage Vo is gradually decreased from Vc2 to Vc1 as time elapses (T1 to T2) as described above, and then is set to 0V. This can reduce the operating noise. Note that, as indicated by a one-dot chain line in the figure, the valve opening drive voltage Vo may be decreased to Vc1 at time T1 and then gradually decreased to 0V until time T2.

  In the above-described on / off valve drive control, the electromagnetic valves 24a and 24b are driven at the same time. However, they may be controlled separately. For example, an example in the case of the valve closing drive voltage Vc will be described with reference to FIG. 5 corresponding to FIG. The valve opening control can be performed in the same manner, and the description thereof is omitted.

  In FIG. 5, apart from the solid line shown in FIG. 4A, the valve closing drive voltage Vc becomes Vc1 when the pedal stroke Sp becomes Sp3 between Sp1 and Sp2, and the pedal stroke Sp. The voltage change map indicated by the alternate long and short dash line is provided so that Vc2 increases to Sp4 until it reaches Sp4 which is larger than Sp2 and reaches Vc2, and thereafter Vc2. In this case, in the drive voltage supply of both the solenoid valves 24a and 24b, either one can be controlled in the same manner as described above with a solid line and the other with a one-dot chain line. The shift between Sp1 and Sp3 in this case corresponds to the difference in stroke at which the first piston 15a and the second piston 15b begin to close the opening ports 16c and 16d of the oil passages 16a and 16b as described above, and Sp2 and Sp4 The deviation may correspond to a difference in stroke for completely closing the ports 16c and 16d.

  By doing in this way, when driving a plurality of solenoid valves (two in the illustrated example), they are not driven simultaneously, but are driven at different timings, so that it is possible to disperse the operating sound, and even more. Silencing can be improved.

  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 shown in FIG. 6 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. 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. 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 the valve closing current setting unit 37.

  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.

  FIG. 7 shows an example of a control result based on the present invention. When the brake pedal 11 is depressed as shown in the first stage of FIG. 7, the valve closing drive voltage Vc is applied as shown in FIG. As a result, the valve drive current for driving the solenoid valves 24a and 24b in the valve closing direction gradually increases as shown in the third stage of the figure. As described above, since the valve closing drive voltage Vc is increased in two stages, the valve driving current does not flow at a stroke, and the operation sound due to the seating sound of the valve body when the valve is closed is reduced, and noise is suppressed.

  When the maximum current Ic2 corresponding to the maximum value Vc2 of the valve closing drive voltage Vc is reached, the electromagnetic valves 24a and 24b are fully closed, and further, as shown in the second stage of FIG. As the brake pressure of the cylinder 15 increases, the stroke of the motor drive cylinder 13 increases as shown in the fourth stage of FIG.

  The valve drive current after the solenoid valves 24a and 24b are completely closed may be supplied with a maintenance current Ic1 (<Ic2) that can maintain the closed state. In the third stage of FIG. It is reduced to the sustain current Ic1. For example, when regenerative braking is performed by regenerative cooperative control from time T2, the stroke of the motor drive cylinder 13 is reduced according to the amount of regenerative braking as shown in the fourth stage of FIG.

  When releasing the braking force, the brake pedal 11 is released, and the brake pedal 11 is returned to the standby position by the return spring. In this case, the solenoid valves 24a and 24b are temporarily closed so that the brake pressure on the master cylinder 15 side is not applied to the wheel cylinders 2b and 3b until the brake pressure of the master cylinder 15 is sufficiently reduced. The drive current is set to the maximum value Ic2 (drive voltage Vc2), and then the valve drive current is reduced. At this time, as described above, the valve opening drive voltage Vo is reduced in two stages, so that the valve drive current does not disappear at a stroke, and the operation sound due to the valve body impulse sound at the time of valve opening decreases, and noise is reduced. It is suppressed.

2b / 3b Wheel cylinder 6 Control unit (control means)
11 Brake pedal (operating member)
11a Displacement sensor (operation amount detection means)
13 Motor driven cylinder (hydraulic pressure generating means)
15 Master cylinders 24a and 24b Solenoid valves 42a and 42b Piping (oil passage)

Claims (6)

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 brake fluid pressure to the oil passage according to the operation amount;
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 control means fully closes the solenoid valve when the operation amount in the direction in which the fluid pressure is generated is detected, and when the operation amount that causes the fluid pressure to disappear is detected, A vehicular brake device, wherein the electromagnetic valve is fully opened, and when the electromagnetic valve is fully opened or fully closed, the drive voltage of the electromagnetic valve is changed including a state of gradually changing.   The control means sets the energization control value to the solenoid valve so that the solenoid valve is closed when the operation amount becomes a predetermined value or more and the brake fluid pressure by the fluid pressure generating means becomes a prescribed value or more. The vehicle brake device according to claim 1, wherein the vehicle brake device is reduced to a value that can be maintained.   The control means controls an energization control value for the electromagnetic valve based on the operation amount and the operation amount of the hydraulic pressure generating means when the operation amount becomes a predetermined value or more. The vehicle brake device according to claim 1.   4. The vehicle according to claim 2, wherein the control unit sets the energization control value to the solenoid valve when the operation amount is equal to or greater than a predetermined value to a constant value lower than a maximum value. 5. Brake device. A plurality of the solenoid valves are provided,
The vehicular brake device according to any one of claims 1 to 4, wherein the control means varies timings of energization of the plurality of electromagnetic valves.   The said control means reduces the electricity supply control value to the said solenoid valve according to time passage, when the said operation amount is less than predetermined value, The time in any one of Claim 1 thru | or 5 characterized by the above-mentioned. Vehicle brake system.

Images