JP2015000582A - Vehicular brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To do away with an incongruity sense by a change of a deceleration when reducing a brake hydraulic pressure.SOLUTION: A vehicular brake device is provided with: a master cylinder operated by a brake pedal; a slave cylinder driven by an electric motor; a hydraulic pressure generation control part controlling the slave cylinder so as to generate a brake hydraulic pressure corresponding to a stroke amount of the brake pedal; and a hysteresis impartment part imparting hysteresis when reducing the brake hydraulic pressure when returning the brake pedal. The vehicular brake device detects an operation speed of the brake pedal and a vehicle speed, corrects a hysteresis amount according to at least one of the operation speed and the vehicle speed to make a change of a deceleration in time of a changeover gentle, and can further reduce an incongruity sense felt by an operator.

Description

  The present invention relates to a vehicle brake device, and more particularly to a vehicle brake device that generates a braking force by an electric actuator.

  Conventionally, there is a so-called brake-by-wire vehicle brake device in which a brake pressure is generated by a cylinder using an electric actuator having an electric motor as a drive source. For example, when the electric actuator is driven so as to generate the brake fluid pressure corresponding to the depression amount (braking operation amount) of the brake pedal, when the operation to return from the depression state of the brake pedal is performed, the mechanical structure of the brake device, etc. Due to the hysteresis generated between the increase side and the decrease side of the operation amount, a phenomenon occurs in which the generation of the braking force does not match the operator's intention. In order to alleviate such a phenomenon, for example, there is a method in which control is performed by determining a target control value to a different value depending on a difference in operation direction during braking (depressing / returning a brake pedal) (for example, Patent Document 1). reference).

  According to the above-mentioned patent document 1, the deceleration with respect to the braking operation amount (pedal stroke amount) is mapped with an increasing curve at the time of depression and a decreasing curve at the time of stepping back, and the target control value is set according to the difference in the operation direction. It is possible to alleviate the hysteresis phenomenon that the braking force varies depending on the operation direction even if the braking operation amount is the same. For example, when switching from the depressed state to the depressed step in the high braking state, the curve shifts to a curve for gradually decreasing the deceleration after passing through a certain deceleration state according to the decrease in the braking operation amount. As a result, it is possible to prevent a significant increase in deceleration due to hysteresis.

JP 2004-322660 A

  However, the deceleration suddenly changes when moving from a constant deceleration state to a decreasing curve. In addition, by stopping the stepping back at the position of the arbitrary braking operation amount, a sudden change in the deceleration occurs even when the deceleration curve shifts to a constant deceleration, and in that case, a residual feeling of deceleration occurs, There is a problem that there is a region where the operator (driver) feels uncomfortable.

  In order to solve such a problem and realize a vehicle brake device that can eliminate a sense of incongruity due to a change in deceleration when the brake fluid pressure is reduced, in the present invention, a braking operation operated by a driver is performed. An operation amount detection means (124) for detecting the braking operation amount of the member (2), a hydraulic pressure generation means (131) for driving the electric actuator (4) in accordance with the braking operation amount to generate a brake hydraulic pressure, Hysteresis applying means (132) for reducing the brake hydraulic pressure generated when the braking operation amount is decreased by the hydraulic pressure generating means with a hysteresis with respect to a case where the braking operation amount is increased; The vehicle brake device includes a means (126) for detecting a vehicle speed and a means (133) for obtaining a braking operation speed when the amount of braking operation decreases. The hysteresis providing means is configured to change the amount of hysteresis between when the braking operation amount increases and when the braking operation amount decreases to the braking operation amount, the vehicle speed, and the braking operation when the braking operation amount is switched to the decreasing side. It was set based on at least one of the speeds.

  According to this, in the brake device that generates the brake hydraulic pressure by the hydraulic pressure generating means, the braking operation amount increases the brake hydraulic pressure generated by the hydraulic pressure generating means in accordance with the braking operation amount (for example, the stroke of the brake pedal). By reducing the case where the brake pressure decreases with hysteresis, it is possible to relieve the uncomfortable feeling caused by the mechanical resistance or the like when the brake fluid pressure is switched from the increase side to the decrease side. Furthermore, by correcting the amount of hysteresis based on the braking operation amount and one of the vehicle speed and the braking operation speed, the change in deceleration at the time of switching can be moderated, making the operator feel more uncomfortable. It can be further reduced.

  In particular, the hysteresis amount may be set to increase as the braking operation amount increases. According to this, it is possible to reduce the deceleration while decelerating by the deceleration corresponding to the magnitude of the braking operation amount when the braking operation is reduced, and perform appropriate deceleration control according to the driver's braking operation amount. It can be carried out.

  Further, the amount of hysteresis is corrected so as to decrease as the vehicle speed increases when the vehicle speed is higher than a predetermined speed, and is corrected so as to increase as the vehicle speed decreases when the vehicle speed is lower than the predetermined speed. Good.

  According to this, since the hysteresis amount is increased with respect to the braking operation amount when the vehicle speed is high, the vehicle behavior is stabilized by providing a margin before the change in the deceleration occurs with respect to the return of the brake pedal. Can be When the vehicle speed is low, the hysteresis amount is reduced with respect to the braking operation amount, so that a quick deceleration can be realized.

  Further, the hysteresis amount may be corrected so as to decrease as the braking operation speed increases.

  When decreasing the deceleration, increasing the braking operation speed is a case where the brake fluid pressure is lowered early, so reducing the brake fluid pressure early by reducing the hysteresis amount reduces the deceleration. , The remaining feeling of deceleration can be suppressed. Here, the remaining feeling of deceleration is a sense of deceleration that is felt when a change in deceleration is still occurring even though the reduction of the braking operation has been completed.

  Further, the brake hydraulic pressure generated when the braking operation amount is reduced by the hydraulic pressure generating means is decreased according to the decrease in the braking operation amount from when the braking operation amount is switched to the side where the braking operation amount is reduced. The ratio of the decrease in the brake fluid pressure with respect to the braking operation amount may be increased as the braking operation amount increases.

  The brake fluid pressure remains constant until the braking operation amount is reduced by the hysteresis amount when the brake operation amount is reduced, whereas the brake fluid pressure is reduced by decreasing the brake fluid pressure from the time of switching. The beginning of the speed change can be changed gently, and when the deceleration is reduced by a predetermined amount, it can be quickly reduced, so that there is no residual feeling of deceleration at the end of the deceleration reduction. be able to.

  Thus, according to the present invention, in the brake device that generates the brake hydraulic pressure by the hydraulic pressure generating means, the brake hydraulic pressure generated by the hydraulic pressure generating means in accordance with the braking operation amount (for example, the stroke of the brake pedal) is braked. By reducing the case where the operation amount increases with a decrease in hysteresis, it is possible to alleviate the uncomfortable feeling caused by mechanical resistance or the like when the brake fluid pressure is switched from the increase side to the decrease side. Furthermore, by correcting the amount of hysteresis based on one of the vehicle speed and braking operation speed, the change in deceleration at the time of switching can be moderated, further reducing the sense of discomfort felt by the operator. obtain.

It is a figure which shows the hydraulic circuit of the brake device 1 for vehicles. It is a block diagram of the control system of the brake device for vehicles. It is a principal part block diagram which shows the part corresponding to this invention inside ESB_ECU. It is a time chart which shows the state at the time of stepping back. It is a figure which shows the map used for increase / decrease in the brake fluid pressure with respect to the pedal stroke amount. It is a figure which shows the map which calculates | requires the amount of hysteresis according to the amount of pedal strokes. It is a figure which shows the map which calculates | requires the amount of hysteresis according to a vehicle speed. It is a figure which shows the map which calculates | requires the amount of hysteresis according to pedal return speed. It is a figure which shows the map showing the rate with respect to pedal stroke amount. It is a figure corresponding to FIG. 5 in the case of controlling using the rate of FIG. It is a figure corresponding to FIG. 4 in the case of controlling using the rate of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a hydraulic circuit of the vehicle brake device 1, and FIG. 2 is a configuration diagram of a control system of the vehicle brake device. As shown in FIGS. 1 and 2, the vehicle brake device 1 according to the embodiment includes a brake pedal 2 as a brake operation member that is rotatably supported by the vehicle body, and hydraulic pressure according to the operation of the brake pedal 2. A master cylinder 3 and a slave cylinder 4 that are generated, and disc brakes 5, 6, 7, and 8 that are driven by the hydraulic pressure of the master cylinder 3 or the slave cylinder 4 are provided.

  The master cylinder 3 is a tandem cylinder, and includes a cylindrical master-side housing 11 and a master-side first piston 12 and a master-side second piston 13 that are displaceably accommodated inside the master-side housing 11. doing. The master side first piston 12 is disposed on the rear side along the axial direction in the master side housing 11, and the master side second piston 13 is disposed on the front side along the axial direction in the master side housing 11. A master-side first hydraulic chamber 15 is defined between the master-side first piston 12 and the master-side second piston 13, and a master-side first piston 13 and the master-side housing 11 have a master between the master-side first piston 12 and the master-side housing 11. A side second hydraulic chamber 16 is defined. Between the master side first piston 12 and the master side second piston 13 and between the master side second piston 13 and the end of the master side housing 11, return springs 17 as compression coil springs are respectively interposed. Has been. The master side first piston 12 and the master side second piston 13 are urged to the rear of the master side housing 11 by the return spring 17. The positions of the master side first piston 12 and the master side second piston 13 in this state are set as initial positions.

  One end of a rod 19 that extends along the axial direction and projects rearward from the master side housing 11 is coupled to the master side first piston 12. The protruding end of the rod 19 is rotatably coupled to the brake pedal 2. Accordingly, when the brake pedal 2 is depressed, the master side first piston 12 and the master side second piston 13 move to the front side of the master side housing 11 against the return spring 17.

  A master-side first output port 21 that communicates with the master-side first hydraulic chamber 15 and a second output port 22 that communicates with the master-side second hydraulic chamber 16 are formed in the master-side housing 11. The master side housing 11 is provided with a master side reservoir tank 23. The master-side reservoir tank 23 supplies brake oil to the master-side first hydraulic chamber 15 and the master-side second hydraulic chamber 16 via a fluid path (reference number omitted) formed in the master-side housing 11. A known seal member (not shown) is provided between the master-side first hydraulic chamber 15, the master-side second hydraulic chamber 16, and the master-side reservoir tank 23. Brake oil does not flow from the first hydraulic chamber 15 and the master-side second hydraulic chamber 16 to the master-side reservoir tank 23.

  The slave cylinder 4 is a tandem cylinder and has a cylindrical slave-side housing 31 and a slave-side first piston 32 and a slave-side second piston 33 accommodated in the slave-side housing 31 so as to be displaceable. doing. The slave-side first piston 32 is disposed on the rear side along the axial direction in the slave-side housing 31, and the slave-side second piston 33 is disposed on the front side along the axial direction in the slave-side housing 31. A slave-side first hydraulic chamber 35 is defined between the slave-side first piston 32 and the slave-side second piston 33, and between the slave-side second piston 33 and the front end portion of the slave-side housing 31, the slave A side second hydraulic chamber 36 is defined. The slave side first piston 32 and the slave side second piston 33 are connected by a connecting rod 37 so as to be relatively movable within a predetermined range. The connecting rod 37 extends along the axial direction of the slave-side housing 31, the front end is fixed to the slave-side second piston 33, and the rear end is supported displaceably with respect to the slave-side first piston 32. Accordingly, the maximum value and the minimum value of the interval between the slave side first piston 32 and the slave side second piston 33 are determined.

  A return spring 38, which is a compression coil spring, is interposed between the slave side first piston 32 and the slave side second piston 33 and between the slave side second piston 33 and the end of the slave side housing 31. Has been. The return-side spring 38 biases the slave-side first piston 32 and the slave-side second piston 33 behind the slave-side housing 31.

  The slave cylinder 4 has a motor 40 that is an electric servomotor as an electric actuator, and a ball screw mechanism 42 to which the rotational force of the motor 40 is transmitted via a gear train 41. The ball screw mechanism 42 moves the slave-side first piston 32 forward against the biasing force of the return spring 38 according to the rotation of the motor 40. In the initial position, the slave-side first piston 32 and the slave-side second piston 33 are disposed most rearward.

  The slave-side housing 31 is formed with a slave-side first output port 45 communicating with the slave-side first hydraulic chamber 35 and a slave-side second output port 46 communicating with the slave-side second hydraulic chamber 36. Yes. The slave side housing 31 is provided with a slave side reservoir tank 47. The slave-side reservoir tank 47 supplies brake oil to the slave-side first hydraulic chamber 35 and the slave-side second hydraulic chamber 36 via a fluid path (not shown) formed in the slave-side housing 31. The master side reservoir tank 23 and the slave side reservoir tank 47 communicate with each other via a communication path 48. A known seal member (not shown) is provided between the slave-side first hydraulic chamber 35, the slave-side second hydraulic chamber 36, and the slave-side reservoir tank 47. Brake oil does not flow from the first fluid pressure chamber 35 and the slave second fluid pressure chamber 36 to the slave reservoir tank 47.

  The master-side first output port 21 is connected to the wheel cylinders 55 and 56 of the left and right rear wheel disc brakes 5 and 6 via the first fluid passage 51, the VSA device 52, the left rear wheel fluid passage 53, and the right rear wheel fluid passage 54. (First system). The second output port 22 of the master cylinder 3 is connected to the wheel cylinders 65 and 66 of the left and right front wheel disc brakes 7 and 8 via the second fluid path 61, the VSA device 52, the left front wheel fluid path 63, and the right front wheel fluid path 64. Connected (second system). The liquid path is constituted by a piping member.

  A first master cut valve 71, which is a normally open solenoid valve, is provided on the path of the first liquid path 51, and a second master cut valve 72, which is a normally open type solenoid valve, is provided on the path of the second liquid path 61. Is provided. A third liquid path 73 branches from a portion of the first liquid path 51 closer to the VSA device 52 than the first master cut valve 71 (downstream side). An output port 45 is connected. A fourth liquid path 74 branches from a portion of the second liquid path 61 closer to the VSA device 52 than the second master cut valve 72 (downstream side). An output port 46 is connected.

  The fifth fluid passage 75 branches off from the portion of the second fluid passage 61 closer to the master cylinder 3 (upstream side) than the second master cut valve 72, and a stroke simulator 76 is provided at the end of the fifth fluid passage 75. It is connected. The stroke simulator 76 is interposed between a cylinder 77, a piston 78 slidably accommodated in the cylinder 77, and between the piston 78 and the inner wall of the cylinder 77, and urges the piston 78 toward one side of the cylinder 77. And a spring 79. The piston 78 divides the inside of the cylinder 77 into a first hydraulic pressure chamber 81 communicating with the fifth hydraulic path 75 and another second hydraulic pressure chamber 82. The spring 79 urges the piston in the direction in which the first hydraulic chamber 81 is reduced. A simulator valve 84 that is a normally open electromagnetic valve is provided on the fifth liquid passage 75.

  The VSA device 52 includes a first brake actuator 85 that controls the left and right rear wheel disc brakes 5 and 6 (first system), and a second brake actuator 86 that controls the left and right front wheel disc brakes 7 and 8 (second system). And have. Since the first and second brake actuators 86 have the same structure, the first brake actuator 85 will be described as a representative.

  The first brake actuator 85 has a first VSA liquid path 91 and a second VSA liquid path 92 connected to the first liquid path 51. Between the first liquid passage 51 and the first VSA liquid passage 91, a regulator valve 93 made of a normally open electromagnetic valve having a variable opening and a parallel arrangement with respect to the regulator valve 93 are arranged from the first liquid passage 51 side. A first check valve 94 that allows the brake fluid to flow to the first VSA fluid passage 91 side is provided. Between the first VSA fluid passage 91 and the left rear wheel fluid passage 53, a first in-valve 95 made of a normally open solenoid valve and a left rear wheel fluid passage 53 arranged in parallel to the first in-valve 95 are arranged. A second check valve 96 that allows the brake fluid to flow from the side toward the first VSA fluid passage 91 is provided. Between the first VSA fluid passage 91 and the right rear wheel fluid passage 54, a second in-valve 98 made of a normally-open electromagnetic valve and a right rear wheel fluid passage 54 arranged in parallel to the second in-valve 98. A third check valve 99 that allows the brake fluid to flow from the side to the first VSA fluid passage 91 side is provided.

  A first out valve 101 made up of a normally closed solenoid valve is provided between the left rear wheel fluid passage 53 and the second VSA fluid passage 92, and between the right rear wheel fluid passage 54 and the second VSA fluid passage 92. A second out valve 102 made of a normally closed electromagnetic valve is provided. A reservoir 103 is connected to the second VSA liquid path 92. The reservoir 103 includes a cylinder connected to the second VSA liquid path 92, a piston accommodated in the cylinder so as to be displaceable, and a return spring that biases the piston toward the second VSA liquid path 92 (all omitted). ), And the piston is displaced when the brake fluid flows from the second VSA fluid passage 92.

  Between the second VSA liquid path 92 and the first liquid path 51, a fourth check valve 108 that allows the brake fluid to flow from the second VSA liquid path 92 side to the first liquid path 51 side, and a normally closed electromagnetic A suction valve 109 consisting of a valve is provided in series from the second VSA liquid passage 92 side in the order described. A portion of the second VSA liquid path 92 between the fourth check valve 108 and the suction valve 109 is connected to the first VSA liquid path 91 via the pump 111. The pump 111 is driven by the electric motor 112 and transports brake fluid from the second VSA fluid path 92 side to the first VSA fluid path 91 side. A fifth check valve 113 and a sixth check valve 114 are provided on the suction side (second VSA liquid path 92 side) and the discharge side (first VSA liquid path 91 side) of the pump 111 to prevent backflow of brake fluid. .

  A first fluid pressure sensor 121 that detects fluid pressure is provided in a portion of the first fluid passage 51 closer to the master cylinder 3 than the first master cut valve 71. A second hydraulic pressure sensor 122 that detects the hydraulic pressure is provided in a portion closer to the VSA device 52 than the second master cut valve 72 in the second hydraulic path 61. Further, a third hydraulic pressure sensor 123 that detects the hydraulic pressure is provided in a portion of the first liquid passage 51 closer to the VSA device 52 than the first master cut valve 71.

  The brake pedal 2 is provided with a pedal position sensor 124 as an operation amount detecting means for detecting a pedal position which is a position of the brake pedal 2. The pedal position sensor 124 detects a pedal stroke amount that is a driver's braking operation amount (depression amount) with an initial state (pedal position = 0) in a state in which the driver does not depress the brake pedal 2.

  The slave cylinder 4 is provided with a motor rotation angle sensor 125 that detects the rotation angle of the motor 40. Each wheel is provided with a wheel speed sensor 126 for detecting the wheel speed.

  FIG. 2 is a configuration diagram of a control system of the vehicle brake device. As shown in FIG. 2, ESB_ECU 130 that is an electronic control unit of the vehicle brake device includes first to third hydraulic pressure sensors 121 to 123, a pedal position sensor 124, a motor rotation angle sensor 125, and wheel speed sensors 126. An output signal is input. The ESB_ECU 130 controls the first and second master cut valves 71 and 72, the simulator valve 84, the slave cylinder 4, and the VSA device 52 based on these output signals.

  The operation of the vehicle brake device 1 configured as described above will be described. When the system functions normally and the first hydraulic pressure sensor 121 detects that the driver depresses the brake pedal 2, the first and second master cut valves 71 and 72, which are normally open solenoid valves, are excited. The simulator valve 84, which is a normally closed electromagnetic valve, is excited and opened. At the same time, the motor 40 of the slave cylinder 4 is actuated to advance the slave-side first piston 32 and the slave-side second piston 33, and brake fluid is supplied to the slave-side first hydraulic chamber 35 and the slave-side second hydraulic chamber 36. Generate pressure. The brake fluid pressure is determined by the VSA device in which the third fluid passage 73 and the fourth fluid passage 74, the first fluid passage 51 and the second fluid passage 61, the regulator valve 93, and the first and second inlet valves 95 and 98 are opened. 52 is transmitted to the wheel cylinders 55, 56, 65, 66 of the respective disc brakes 5 to 8 through the brake 52 to brake each wheel.

  At this time, since the simulator valve 84 composed of a normally closed electromagnetic valve is excited and opened, the brake hydraulic pressure generated by the master-side second hydraulic chamber 16 is transmitted to the hydraulic chamber of the stroke simulator 76, and its piston By moving 78 against the spring 79, the stroke of the brake pedal 2 is allowed and a pseudo pedal reaction force is generated.

  When the VSA device 52 is not in operation, the regulator valve 93 is demagnetized and opened, the suction valve 109 is demagnetized and closed, and the first and second in valves 95 and 98 are demagnetized and opened, The first and second out valves 101 and 102 are demagnetized and closed. Accordingly, the brake fluid pressure generated in the first fluid passage 51 and the second fluid passage 61 is supplied to the wheel cylinders 55, 56, 65 and 66 through the regulator valve 93 and the first and second in valves 95 and 98.

  When the VSA device 52 is operated, the pump 111 is driven with the suction valve 109 excited and opened, and is pressurized by the pump 111 from the first liquid passage 51 and the second liquid passage 61 through the suction valve 109. Brake fluid is supplied to the first VSA fluid passage 91. Therefore, by exciting the regulator valve 93 and adjusting the opening, the brake fluid pressure in the first VSA passage is regulated, and the wheel is passed through the first and second in-valves 95 and 98 that have opened the brake fluid pressure. The cylinders 55, 56, 65 and 66 can be selectively supplied. Thereby, even when the driver does not step on the brake pedal 2, the braking force of the four wheels can be individually controlled. Thereby, turning performance improvement, straight running stability improvement, and anti-lock control of a brake can be performed.

  When the power supply fails, the first and second master cut valves 71 and 72 which are normally open solenoid valves are automatically opened, and the simulator valve 84 which is a normally closed solenoid valve is automatically closed. The first and second in valves 95 and 98 that are normally open solenoid valves and the regulator valve 93 are automatically opened, and the first and second out valves 101 and 102 that are normally closed solenoid valves and the suction valve. The valve 109 is automatically closed. In this state, the brake fluid pressure generated in the master-side first hydraulic chamber 15 and the master-side second hydraulic chamber 16 of the master cylinder 3 is not absorbed by the stroke simulator 76, and the first and second fluid passages. 61, the wheel cylinders 55, 56, 65, 66 of the disc brake 5-8 device of each wheel can be operated via the VSA device 52, and the braking force can be generated without hindrance.

  Next, the control point based on this invention is demonstrated. The present invention is applied to control when the brake pedal 2 is stepped back from a state where the brake pedal 2 is depressed to generate a braking force.

  FIG. 3 is a principal block diagram showing a part of the ESB_ECU 130 corresponding to the present invention. A hydraulic pressure generation control unit 131 as a hydraulic pressure generation unit to which output signals of the first to third hydraulic pressure sensors 121 to 123 are input, and a hysteresis application unit 132 as a hysteresis application unit to which an output signal of the pedal position sensor 124 is input. And an operation speed calculation unit 133 as means for obtaining a braking operation speed that is a displacement speed of the brake pedal 2 based on an output signal of the pedal position sensor 124. The output signal of the operation speed calculation unit 133 is input to the hysteresis applying unit 132, and the output signal of the wheel speed sensor 126 is input to the hysteresis applying unit 132. The slave cylinder 4 is driven and controlled by the output signal of the hydraulic pressure generation control unit 131. The vehicle pressure increase map may be provided in the hydraulic pressure generation control unit 131 so that the output signal of the wheel speed sensor 126 passes through the hysteresis applying unit 132.

  3, the stroke change amount (reduced target hydraulic pressure) as the return amount of the brake pedal 2 and the return speed of the brake pedal 2 in the driver factor as the input factor and the return speed of the brake pedal 2 are output signals from the pedal position sensor 124. The vehicle speed (inertia) of the vehicle factor is processed by the output signal of the wheel speed sensor 126, and the deceleration of the vehicle factor is similarly processed by the stroke amount of the brake pedal 2 (brake hydraulic pressure at the start of return). Control according to the invention can be performed.

  FIG. 4 is a time chart in a case where the brake pedal 2 is stepped back from a state where the pedal is depressed by a certain amount and is maintained at a midway position. From the top, the pedaling force F, the pedal stroke amount S, the brake fluid pressure P, the decrease The change of the speed G is shown.

  The hysteresis applying unit 132 obtains a target control value of the brake hydraulic pressure P to which the hysteresis is added based on the input signal of the pedal stroke amount S using the map of FIG. 5, and sends the target control value to the hydraulic pressure generation control unit 131. Output. The hydraulic pressure generation control unit 131 drives and controls the slave cylinder 4 according to the target control value signal.

  The hysteresis applying unit 132 obtains a target control value of the brake fluid pressure P (deceleration G) with respect to the pedal stroke amount S using the map of FIG. When the brake fluid pressure P is increased, a target control value is obtained using a pressure increase map curve indicated by a two-dot chain line in FIG. 5, and when the brake fluid pressure P is decreased, a pressure reduction map indicated by a solid line in FIG. To obtain the target control value. As shown in FIG. 6, the hysteresis amount ΔS with respect to the pedal stroke amount S is set so as to increase as the pedal stroke amount S increases and converge on the smaller side. When the hydraulic pressure generation control unit 131 controls the brake hydraulic pressure P using the pressure increase map curve, the hydraulic pressure generation control is performed by passing the output signal of the pedal position sensor 124 through the hysteresis applying unit 132. You may output to the part 131.

  As described above, when the pedal stroke amount S starts to decrease (return) from S1 at the timing T2, the map for obtaining the target control value is moved to the decompression map indicated by the solid line in FIG. While moving from the pressure increase map to the pressure decrease map, the brake fluid pressure P1 obtained from the pressure increase map is maintained according to the pedal stroke amount S1. When the pressure reduction map (solid line) is reached as the pedal stroke amount S decreases, the target control value is decreased according to the decrease in the pedal stroke amount S using the pressure reduction map thereafter. In this case, the hysteresis amount is ΔS1.

  FIG. 6 is a map for obtaining the hysteresis amount ΔS with respect to the pedal stroke amount S when the pedal stroke amount S starts to decrease. As shown in the figure, the hysteresis amount ΔS is set to increase to the negative side as the pedal stroke amount S increases. The hysteresis amount ΔS1 corresponding to the pedal stroke amount S1 is obtained using this map. The reason why the hysteresis amount ΔS is negative is to provide a decompression map that is decreased by the hysteresis amount ΔS in the decreasing direction of the pedal stroke amount S with respect to the pressure increase map.

  As shown in FIG. 4, when the brake pedal 2 is first depressed by the pedal stroke amount S1 with the depression force F1, the brake fluid pressure P1 is generated, and the deceleration G1 is generated accordingly. From this state, the depression force of the brake pedal 2 is weakened at the timing of T1, and the pedal stroke amount S starts to return from the timing T2. The brake fluid pressure P is constant (P1) from the timing T2 to the pedal stroke amount S2 reaching the decompression map, decreases after moving to the decompression map, and after the timing T3 when the decrease of the pedal stroke amount S is stopped, the pedal stroke. A value (P2) corresponding to the amount S3 is obtained. As a result, it is possible to delay the start of the decrease of the brake fluid pressure P and to gradually change the deceleration G at the start of the change of the deceleration G, so that the driver does not feel uncomfortable.

  On the other hand, for example, in order to alleviate the uncomfortable feeling caused by the hysteresis caused by the mechanical structure of the brake device described in the background art, it is conceivable to provide a low-pass filter in the circuit for obtaining the target control value. Changes in the pressure P and the deceleration G are shown by a two-dot chain line in FIG. In the case where the low-pass filter is provided, as indicated by the two-dot chain line in the figure, the brake hydraulic pressure P starts to decrease with the decrease in the pedal stroke amount S from the start of the decrease in the pedal stroke amount S (T2). Since it is gradually reduced by the filter, there is an effect that a sudden change in the deceleration G can be mitigated. However, the brake fluid pressure P stops decreasing after the driver stops decreasing the pedal stroke amount S for a while (T3 to T4). In this case, since the deceleration G changes even after the return operation of the brake pedal 2 is stopped, the feeling of the remaining deceleration G occurs, and the driver feels uncomfortable.

  On the other hand, since the brake fluid pressure P is reduced by using a pressure reduction map that is farther away from the pressure increase map by the amount of hysteresis ΔS, the brake fluid pressure P can be reduced by a change different from that at the time of pressure increase. Since no delay occurs, the desired brake fluid pressure P2 (deceleration G2) can be reached at timing T3 earlier than timing T4 as shown in FIG. Thereby, even after the decrease in the pedal stroke amount S is stopped, the uncomfortable feeling that the deceleration changes and the remaining feeling of the deceleration occurs can be solved.

  When the pedal stroke amount S is small (S4 in FIG. 5), the hysteresis amount ΔS4 (<ΔS1) is obtained from the map in FIG. 6, and the boosting map is moved to the decrease side of the pedal stroke amount S by the hysteresis amount. It is possible to use the reduced pressure map (the broken pressure map shown by the broken line in FIG. 5). In this case, the brake fluid pressure P (deceleration) is reduced in the same manner as described above.

  In the first embodiment, the hysteresis amount ΔS is obtained on the basis of the pedal stroke amount S at the start of the decrease in the pedal stroke amount S. However, the hysteresis amount obtained using another parameter may be corrected, The procedure for obtaining the hysteresis correction amount will be described below.

  FIG. 7 is a diagram showing an example of a map for obtaining the hysteresis correction amount ΔSv according to the vehicle speed. As shown in the figure, a hysteresis correction amount ΔSv1 is set so that the vehicle speed V is 0 and maximizes on the negative side. When the vehicle speed V is less than a predetermined vehicle speed (for example, an arbitrary vehicle speed in the middle speed range) Vd, as the vehicle speed Vd approaches The hysteresis correction amount ΔSv decreases so that the change becomes smaller, the hysteresis correction amount ΔSv is 0 at a predetermined vehicle speed Vd, and the hysteresis correction amount ΔSv becomes a positive value and the vehicle speed V is higher at a higher side than the predetermined vehicle speed Vd. It is designed to increase with a smaller change.

  Here, a procedure for creating a map for obtaining the hysteresis correction amount ΔSv to be corrected according to the vehicle speed V will be described. When creating a map (FIG. 6) for obtaining the hysteresis amount ΔS corresponding to the pedal stroke amount S, for example, the vehicle decelerates with a deceleration of 0 to 1 G with respect to the entire operation amount of the pedal stroke amount S at a predetermined vehicle speed Vd. The hysteresis amount ΔS to be obtained is set. Based on this, a map set for the predetermined vehicle speed Vd even when the vehicle speed V is different from the predetermined vehicle speed Vd in consideration of the effects of braking inertia and pitching due to the difference in the vehicle speed V (FIG. 6). The hysteresis correction amount ΔSv to be corrected according to the vehicle speed V is set so that a change equivalent to the appropriate deceleration due to is obtained.

  This hysteresis correction amount ΔSv is added to the hysteresis amount ΔS obtained from FIG. 6 to obtain a target control value. As a result, the hysteresis amount ΔS increases in the low speed region of the vehicle speed V, and the hysteresis amount ΔS decreases in the high speed region. Note that the change (decrease amount) in the high speed range is generally smaller than the change (increase amount) in the low speed range. By using the target control value corrected in this way, it is possible to avoid the influence of inertia and pitching during braking due to the vehicle factor (vehicle speed).

  FIG. 8 is a diagram showing an example of a map for obtaining the hysteresis correction amount ΔSp according to the pedal return speed (braking operation speed). As shown in the figure, the hysteresis correction amount ΔSp is set to increase and change as the pedal return speed (mm / s) Bp increases. When the pedal return speed Bp is large, the brake pedal 2 is operated suddenly. In this case, the above-described start of the decrease in the pedal stroke amount S suddenly changes. Therefore, the correction amount may be increased. Thereby, the remaining feeling of the deceleration caused by the driver's operation can be reduced. On the other hand, when the pedal return speed Bp is low (when the brake pedal 2 is operated gently), the above-described start of the decrease in the pedal stroke amount S changes gently, and the change in the deceleration G also becomes gentle. Therefore, there is no need to increase the correction amount.

  The combination of the correction amounts may be arbitrary, and either one or both of the vehicle speed and the pedal return speed can be added. As a result, the hysteresis effect considering the vehicle speed V and the pedal return speed Bp can be added to the hysteresis effect corresponding only to the pedal stroke amount S, and the brake fluid pressure can be increased with a more appropriate hysteresis amount ΔS (= ΔS + ΔSv + ΔSp). P pressure reduction control can be performed.

  Furthermore, the process up to the target control value using the hysteresis amount may be controlled using the rate Rs, and the control procedure in that case will be described with reference to FIGS. FIG. 9 is an example of a map representing the change in the hysteresis amount with respect to the deceleration as a rate Rs with respect to the pedal stroke amount S. FIG. 10 is a diagram corresponding to FIG. 5 showing a change in the brake hydraulic pressure P in accordance with a change in the pedal stroke amount S when the control is performed using the rate Rs.

  As shown in FIG. 9, the rate Rs used for this control is set so as to gradually decrease as the pedal stroke amount S increases. As described above, the hysteresis amount (ΔS + ΔSv + ΔSp) is maintained while the brake fluid pressure P is maintained. This shows the rate at which the brake fluid pressure P is also reduced as the pedal stroke S is reduced, compared to the case where the pedal stroke amount S is returned. For example, in the depressurization process of the brake hydraulic pressure P that reaches the depressurization map set using the hysteresis amount ΔS1 (= ΔS + ΔSv + ΔSp) in the case of the pedal stroke amount S1 shown in FIG. 5, the pedal stroke amount S1 to the rate Rs (in FIG. 9). The brake fluid pressure P is reduced using a decrease rate by the rate Rs) corresponding to the pedal stroke amount S1. In this case, the change in the brake hydraulic pressure P (deceleration G) according to the pedal stroke amount S is as shown by an arrow line inclined obliquely downward to the left shown in FIG.

  As shown in FIGS. 10 and 11, the brake fluid pressure P starts to decrease from the pedal stroke amount S1 according to the decrease in the stroke, and after reaching the decompression map (brake fluid pressure P3), the pedal according to the decompression map. It decreases until it reaches the stroke amount S3 (brake hydraulic pressure P2 / deceleration G3). As a result, the deceleration start can be changed more slowly and at the same time as in FIG. 5, the control can be performed so as not to feel the remaining feeling of deceleration by ending the deceleration end as quickly as in FIG. 5. Therefore, the pitching can be controlled in the return operation of the brake pedal 2 at the time of deceleration, and the deceleration control can be performed without causing the driver to feel uncomfortable. In the case of a small pedal stroke amount S4, the deceleration G (brake hydraulic pressure P) at the start of the return operation of the brake pedal 2 is small, and therefore an appropriate change in deceleration can be obtained by reducing it relatively slowly. The decompression map is reached with a small slope according to the rate Rs obtained from FIG.

  As described above, according to the present invention, the change in the pedal stroke amount, that is, the change in the appropriate brake fluid pressure according to the driver's request is generated, so that the deceleration starts to decrease gradually and the deceleration is reduced. When the decrease is stopped, it is possible to prevent the remaining feeling of deceleration from occurring.

  The present invention has been described with reference to the preferred embodiments. However, as those skilled in the art can easily understand, the present invention is not limited to such embodiments, and the gist of the present invention. As long as it does not deviate from the above, it can be appropriately changed. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

1 Brake device for vehicle 2 Brake pedal (braking operation member)
4 Slave cylinder (electric actuator)
124 pedal position sensor (operation amount detection means)
126 Wheel speed sensor (means for detecting vehicle speed)
131 Fluid pressure generation control unit (fluid pressure generating means)
132 Hysteresis imparting section (hysteresis imparting means)
133 Operation speed calculation unit (means for obtaining braking operation speed)

Claims (5)

An operation amount detecting means for detecting a braking operation amount of a braking operation member operated by a driver, a hydraulic pressure generating means for driving the electric actuator according to the braking operation amount to generate a brake hydraulic pressure, and the hydraulic pressure generation In the vehicle brake device, comprising: hysteresis applying means for reducing the brake hydraulic pressure generated when the braking operation amount is decreased by means with a hysteresis with respect to the case where the braking operation amount is increased,
Means for detecting a vehicle speed, and means for obtaining a braking operation speed when the amount of braking operation decreases,
The hysteresis applying means changes the amount of hysteresis between when the braking operation amount increases and when the braking operation amount decreases to when the braking operation amount is switched to the decreasing side, the vehicle speed, and the braking The vehicle brake device is set based on at least one of the operation speeds.   The vehicular brake device according to claim 1, wherein the hysteresis amount is set to increase as the braking operation amount increases.   The hysteresis amount is corrected so as to decrease as the vehicle speed increases when the vehicle speed is higher than a predetermined speed, and is corrected so as to increase as the vehicle speed decreases when the vehicle speed is lower than the predetermined speed. The vehicle brake device according to claim 1, wherein the vehicle brake device is a vehicle brake device.   The vehicular brake device according to any one of claims 1 to 3, wherein the hysteresis amount is corrected so as to decrease as the braking operation speed increases. The brake hydraulic pressure generated when the braking operation amount is decreased by the hydraulic pressure generating means is decreased according to the decrease in the braking operation amount from when the braking operation amount is switched to the side where the braking operation amount is decreased.
5. The vehicle brake device according to claim 1, wherein a rate of decrease in the brake fluid pressure with respect to the braking operation amount is increased as the braking operation amount is increased.

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