JP2008174221A - Brake control device and brake control method - Google Patents

Abstract

It is possible to satisfactorily determine the presence or absence of a brake operation by a driver.
A brake control device determines that a braking request from a driver is generated when a braking on determination condition is satisfied, and a braking request from the driver when a braking off determination condition is satisfied. There is provided a brake ECU 70 that determines that is released. The brake ECU 70 may use a condition different from the negation of the brake-on determination condition as the brake-off determination condition. The brake ECU 70 may be set so that the wheel cylinder pressure is used for the brake-on determination condition and the wheel cylinder pressure is not used for the brake-off determination condition.
[Selection] Figure 1

Description

  The present invention relates to a brake control device and a brake control method for controlling braking force applied to wheels provided in a vehicle.

For example, Patent Literature 1 and Patent Literature 2 disclose a brake control system using so-called brake-by-wire. The brake-by-wire detects a driver's brake operation and generates a necessary braking force by electronic control.
JP 2005-35471 A JP 2006-123889 A

  With brake-by-wire, it is necessary to detect the driver's brake operation. In order to reliably generate a braking force in response to a request from the driver, the brake system is required to have a high fail-safe property with respect to detection of a brake operation. It is also required that the braking force is not generated by mistake when the brake operation is not performed.

  The present invention provides a brake control device and a brake control method that satisfactorily determine the presence or absence of a brake operation by a driver.

  The brake control device according to the first aspect of the present invention determines that a braking request from the driver has occurred when the braking on determination condition is satisfied, and from the driver when the braking off determination condition is satisfied. A control unit that determines that the braking request is released.

  The brake control device according to the second aspect of the present invention determines that a braking request from the driver has occurred when the braking on determination condition is satisfied, and from the driver when the braking off determination condition is satisfied. The brake control device includes a control unit that determines that the braking request is released, and the control unit sets a condition different from the negation of the brake on determination condition as the brake off determination condition.

  According to this aspect, the brake-off condition is not set simply as a negation of the brake-on condition, but is set to a condition different from the negation of the brake-on determination condition. Here, the negation of the condition refers to a condition “not condition A” with respect to the condition A. For this reason, it is possible to set an optimum determination condition in accordance with the behavior of the brake system when braking is turned on and off, that is, when a braking request is generated and released. In particular, it is possible to set the determination condition in consideration of the difference in the measurement amount for detecting braking on and braking off, for example, the fluctuation of the hydraulic fluid pressure on and off. As a result, it is possible to satisfactorily determine whether or not there is a braking request from the driver.

  The control unit may be set so that the wheel cylinder pressure is used for the brake-on determination condition and the wheel cylinder pressure is not used for the brake-off determination condition. According to this aspect, the control unit determines braking off, that is, release of the braking request based on another input signal without using the wheel cylinder pressure. When the driver's brake operation is released, the wheel cylinder pressure may remain due to circumstances. For this reason, it can be possible to determine braking off satisfactorily by avoiding the use of the wheel cylinder pressure when determining braking off.

  The control unit may determine braking off using an input signal having a higher response than the wheel cylinder pressure with respect to the release of the brake operation by the driver. According to this aspect, the control unit determines braking off based on an input signal having a higher response than the wheel cylinder pressure, for example, an input signal from the stop lamp switch, with respect to the release of the brake operation by the driver. Thus, by using an input signal that changes immediately in response to the release of the brake operation instead of the wheel cylinder pressure, it is possible to quickly determine the braking off.

  The control unit may determine braking off using an input signal from the stop lamp switch. In this way, using the input signal from the stop lamp switch, it is possible to quickly determine braking off.

  The brake control method according to the third aspect of the present invention determines that a braking request from the driver has occurred when the braking on determination condition is satisfied, and from the driver when the braking off determination condition is satisfied. It is determined that the braking request is released.

  The brake control method according to the fourth aspect of the present invention determines that a braking request from the driver has occurred when the braking on determination condition is satisfied, and from the driver when the braking off determination condition is satisfied. It is determined that the braking request is released. A condition different from the negation of the brake-on determination condition is set as a brake-off determination condition.

  In the first and third aspects, the brake-off determination condition may be a negative of the brake-on determination condition.

  According to the present invention, it is possible to satisfactorily determine whether or not the driver has operated the brake.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a system diagram showing a brake control device 20 according to an embodiment of the present invention. A brake control device 20 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and controls braking force applied to four wheels provided on the vehicle. The brake control device 20 according to the present embodiment is mounted on, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine as a travel drive source. In such a hybrid vehicle, each of regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy and hydraulic braking by the brake control device 20 can be used for braking the vehicle. The vehicle in the present embodiment can execute brake regenerative cooperative control that generates a desired braking force by using both the regenerative braking and the hydraulic braking together.

  As shown in FIG. 1, the brake control device 20 includes disc brake units 21FR, 21FL, 21RR and 21RL provided for each wheel, a master cylinder unit 27, a power hydraulic pressure source 30, a hydraulic pressure, Actuator 40.

  Disc brake units 21FR, 21FL, 21RR, and 21RL apply braking force to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. The master cylinder unit 27 as the manual hydraulic pressure source in the present embodiment sends the brake fluid pressurized according to the amount of operation by the driver of the brake pedal 24 as the brake operation member to the disc brake units 21FR to 21RL. To do. The power hydraulic pressure source 30 can send the brake fluid as the working fluid pressurized by the power supply to the disc brake units 21FR to 21RL independently from the operation of the brake pedal 24 by the driver. is there. The hydraulic actuator 40 appropriately adjusts the hydraulic pressure of the brake fluid supplied from the power hydraulic pressure source 30 or the master cylinder unit 27 and sends it to the disc brake units 21FR to 21RL. Thereby, the braking force with respect to each wheel by hydraulic braking is adjusted.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 27, the power hydraulic pressure source 30, and the hydraulic actuator 40 will be described in more detail below. Each of the disc brake units 21FR to 21RL includes a brake disc 22 and wheel cylinders 23FR to 23RL incorporated in the brake caliper, respectively. The wheel cylinders 23FR to 23RL are connected to the hydraulic actuator 40 via different fluid passages. Hereinafter, the wheel cylinders 23FR to 23RL are collectively referred to as “wheel cylinders 23” as appropriate.

  In the disc brake units 21FR to 21RL, when brake fluid is supplied to the wheel cylinder 23 from the hydraulic actuator 40, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel. Thereby, a braking force is applied to each wheel. In the present embodiment, the disc brake units 21FR to 21RL are used, but other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In this embodiment, the master cylinder unit 27 is a master cylinder with a hydraulic booster, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir. The hydraulic booster 31 is connected to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, and transmits it to the master cylinder 32. When the brake fluid is supplied from the power hydraulic pressure source 30 to the hydraulic pressure booster 31 via the regulator 33, the pedal effort is amplified. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 34 for storing brake fluid is disposed above the master cylinder 32 and the regulator 33. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 is in communication with both the reservoir 34 and the accumulator 35 of the power hydraulic pressure source 30, and the reservoir 34 is used as a low pressure source, the accumulator 35 is used as a high pressure source, and the hydraulic pressure is approximately equal to the master cylinder pressure. Is generated. Hereinafter, the hydraulic pressure in the regulator 33 is appropriately referred to as “regulator pressure”. The master cylinder pressure and the regulator pressure do not need to be exactly the same pressure. For example, the master cylinder unit 27 can be designed so that the regulator pressure is slightly higher.

  The power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 27. When the pressure of the brake fluid in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake fluid is returned to the reservoir 34.

  As described above, the brake control device 20 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a supply source of brake fluid to the wheel cylinder 23. A master pipe 37 is connected to the master cylinder 32, a regulator pipe 38 is connected to the regulator 33, and an accumulator pipe 39 is connected to the accumulator 35. These master pipe 37, regulator pipe 38 and accumulator pipe 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of flow paths are formed, and a plurality of electromagnetic control valves. The flow paths formed in the actuator block include individual flow paths 41, 42, 43 and 44 and a main flow path 45. The individual flow paths 41 to 44 are respectively branched from the main flow path 45 and connected to the wheel cylinders 23FR, 23FL, 23RR, 23RL of the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Thereby, each wheel cylinder 23 can communicate with the main flow path 45.

  In addition, ABS holding valves 51, 52, 53 and 54 are provided in the middle of the individual flow paths 41, 42, 43 and 44. Each of the ABS holding valves 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and both are normally open electromagnetic control valves that are opened when the solenoid is in a non-energized state. Each of the ABS holding valves 51 to 54 in the opened state can distribute the brake fluid in both directions. That is, the brake fluid can flow from the main flow path 45 to the wheel cylinder 23, and conversely, the brake fluid can also flow from the wheel cylinder 23 to the main flow path 45. When the solenoid is energized and the ABS holding valves 51 to 54 are closed, the flow of brake fluid in the individual flow paths 41 to 44 is blocked.

  Further, the wheel cylinder 23 is connected to the reservoir channel 55 via pressure reducing channels 46, 47, 48 and 49 connected to the individual channels 41 to 44, respectively. ABS decompression valves 56, 57, 58 and 59 are provided in the middle of the decompression channels 46, 47, 48 and 49. Each of the ABS pressure reducing valves 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the ABS pressure reducing valves 56 to 59 are closed, the flow of brake fluid in the pressure reducing flow paths 46 to 49 is blocked. When the solenoid is energized and the ABS pressure reducing valves 56 to 59 are opened, the brake fluid is allowed to flow through the pressure reducing flow paths 46 to 49, and the brake fluid flows from the wheel cylinder 23 to the pressure reducing flow paths 46 to 49 and It returns to the reservoir 34 via the reservoir channel 55. The reservoir channel 55 is connected to the reservoir 34 of the master cylinder unit 27 via a reservoir pipe 77.

  The main channel 45 has a separation valve 60 in the middle. By this separation valve 60, the main channel 45 is divided into a first channel 45 a connected to the individual channels 41 and 42 and a second channel 45 b connected to the individual channels 43 and 44. The first flow path 45a is connected to the front wheel wheel cylinders 23FR and 23FL via the individual flow paths 41 and 42, and the second flow path 45b is connected to the rear wheel wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the separation valve 60 is in the closed state, the flow of brake fluid in the main flow path 45 is blocked. When the solenoid is energized and the separation valve 60 is opened, the brake fluid can be circulated bidirectionally between the first flow path 45a and the second flow path 45b.

  In the hydraulic actuator 40, a master channel 61 and a regulator channel 62 communicating with the main channel 45 are formed. More specifically, the master channel 61 is connected to the first channel 45 a of the main channel 45, and the regulator channel 62 is connected to the second channel 45 b of the main channel 45. The master channel 61 is connected to a master pipe 37 that communicates with the master cylinder 32. The regulator channel 62 is connected to a regulator pipe 38 that communicates with the regulator 33.

  The master channel 61 has a master cut valve 64 in the middle. The master cut valve 64 is provided on the brake fluid supply path from the master cylinder 32 to each wheel cylinder 23. The master cut valve 64 has a solenoid and a spring that are ON / OFF-controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The master cut valve 64 in the opened state can cause the brake fluid to flow in both directions between the master cylinder 32 and the first flow path 45 a of the main flow path 45. When a prescribed control current is applied to the solenoid and the master cut valve 64 is closed, the flow of brake fluid in the master flow path 61 is interrupted.

  A stroke simulator 69 is connected to the master channel 61 via a simulator cut valve 68 on the upstream side of the master cut valve 64. That is, the simulator cut valve 68 is provided in a flow path connecting the master cylinder 32 and the stroke simulator 69. The simulator cut valve 68 has a solenoid and a spring that are ON / OFF controlled, and the valve opening state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally closed electromagnetic control valve that is closed in some cases. When the simulator cut valve 68 is closed, the flow of brake fluid between the master flow path 61 and the stroke simulator 69 is blocked. When the solenoid is energized and the simulator cut valve 68 is opened, the brake fluid can be circulated bidirectionally between the master cylinder 32 and the stroke simulator 69.

  The stroke simulator 69 includes a plurality of pistons and springs, and creates a reaction force corresponding to the depression force of the brake pedal 24 by the driver when the simulator cut valve 68 is opened. As the stroke simulator 69, in order to improve the feeling of brake operation by the driver, it is preferable to employ one having a multistage spring characteristic.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 is provided on the brake fluid supply path from the regulator 33 to each wheel cylinder 23. The regulator cut valve 65 also has a solenoid and a spring that are controlled to be turned on and off, and the closed state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is turned off. It is a normally open electromagnetic control valve that is opened in some cases. The regulator cut valve 65 that has been opened can cause the brake fluid to flow in both directions between the regulator 33 and the second flow path 45 b of the main flow path 45. When the solenoid is energized and the regulator cut valve 65 is closed, the flow of brake fluid in the regulator flow path 62 is blocked.

  In the hydraulic actuator 40, an accumulator channel 63 is also formed in addition to the master channel 61 and the regulator channel 62. One end of the accumulator channel 63 is connected to the second channel 45 b of the main channel 45, and the other end is connected to an accumulator pipe 39 that communicates with the accumulator 35.

  The accumulator flow path 63 has a pressure-increasing linear control valve 66 in the middle. Further, the accumulator channel 63 and the second channel 45 b of the main channel 45 are connected to the reservoir channel 55 via the pressure-reducing linear control valve 67. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. In the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67, the opening degree of the valve is adjusted in proportion to the current supplied to each solenoid.

  The pressure-increasing linear control valve 66 is provided as a common pressure-increasing control valve for each of the wheel cylinders 23 provided corresponding to each wheel. Similarly, the pressure reducing linear control valve 67 is provided as a pressure reducing control valve common to the wheel cylinders 23. That is, in this embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common control valves that control the supply and discharge of the working fluid sent from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as. Thus, if the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are made common to each wheel cylinder 23, it is preferable from the viewpoint of cost as compared with the case where a linear control valve is provided for each wheel cylinder 23.

  Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the pressure of the brake fluid in the accumulator 35 and the pressure of the brake fluid in the main flow path 45, and the inlet / outlet of the pressure-reducing linear control valve 67. The pressure difference therebetween corresponds to the pressure difference between the brake fluid pressure in the main flow path 45 and the brake fluid pressure in the reservoir 34. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship of F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  In the brake control device 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by a brake ECU 70 as a control unit in the present embodiment. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 can communicate with a host hybrid ECU (not shown) and the like, and based on control signals from the hybrid ECU and signals from various sensors, the pump 36 of the power hydraulic pressure source 30 and the hydraulic pressure The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the actuator 40 are controlled.

  Further, a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 are connected to the brake ECU 70. The regulator pressure sensor 71 detects the pressure of the brake fluid in the regulator flow path 62 on the upstream side of the regulator cut valve 65, that is, the regulator pressure, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure of the brake fluid in the accumulator flow path 63, that is, the accumulator pressure on the upstream side of the pressure increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake fluid in the first flow path 45a of the main flow path 45, and gives a signal indicating the detected value to the brake ECU 70. The detection values of the pressure sensors 71 to 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area of the brake ECU 70.

  When the separation valve 60 is opened and the first flow path 45 a and the second flow path 45 b of the main flow path 45 communicate with each other, the output value of the control pressure sensor 73 is the low pressure of the pressure-increasing linear control valve 66. This indicates the hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 and the output value can be used to control the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. When the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed and the master cut valve 64 is opened, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the separation valve 60 is opened so that the first flow path 45a and the second flow path 45b of the main flow path 45 communicate with each other, and the ABS holding valves 51 to 54 are opened, while the ABS pressure reducing valves 56 are opened. When? 59 is closed, the output value of the control pressure sensor 73 indicates the working fluid pressure acting on each wheel cylinder 23, i.e., the wheel cylinder pressure.

  Further, the sensor connected to the brake ECU 70 includes a stroke sensor 25 provided on the brake pedal 24. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The output value of the stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70. In the present embodiment, the stroke sensor 25 has two contact points, and can output two measured values to the brake ECU 70 as if they seemed to be two sensors.

  A stop lamp switch 80 is connected to the brake ECU 70. The stop lamp switch 80 is turned on when the brake pedal 24 is depressed. As a result, a stop lamp (not shown) is turned on. When the depression of the brake pedal 24 is released, the stop lamp switch 80 is turned off and the stop lamp is turned off. A signal indicating the lighting state of the stop lamp switch 80 is input from the stop lamp switch 80 to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70.

  The brake control device 20 configured as described above can execute brake regeneration cooperative control. The brake control device 20 starts braking in response to a braking request. The braking request is generated when a braking force should be applied to the vehicle, for example, when the driver operates the brake pedal 24. In response to the braking request, the brake ECU 70 calculates a required braking force, and calculates a required hydraulic braking force that is a braking force to be generated by the brake control device 20 by subtracting the braking force due to regeneration from the required braking force. Here, the value of the braking force by regeneration is supplied from the hybrid ECU to the brake control device 20. Then, the brake ECU 70 calculates the target hydraulic pressure of each wheel cylinder 23FR to 23RL based on the calculated required hydraulic braking force. The brake ECU 70 determines the value of the control current supplied to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 based on the feedback control law so that the wheel cylinder pressure becomes the target hydraulic pressure.

  As a result, in the brake control device 20, the brake fluid is supplied from the power hydraulic pressure source 30 to the wheel cylinders 23 via the pressure-increasing linear control valve 66, and braking force is applied to the wheels. Further, brake fluid is discharged from each wheel cylinder 23 through the pressure-reducing linear control valve 67 as necessary, and the braking force applied to the wheel is adjusted. In the present embodiment, a wheel cylinder pressure control system is configured including the power hydraulic pressure source 30, the pressure-increasing linear control valve 66, the pressure-decreasing linear control valve 67, and the like. Braking force control by so-called brake-by-wire is performed by the wheel cylinder pressure control system. The wheel cylinder pressure control system is provided in parallel to the brake fluid supply path from the master cylinder unit 27 to the wheel cylinder 23.

  At this time, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid sent from the regulator 33 is not supplied to the wheel cylinder 23. Further, the brake ECU 70 closes the master cut valve 64 and opens the simulator cut valve 68. This is because the brake fluid sent from the master cylinder 32 in accordance with the operation of the brake pedal 24 by the driver is supplied not to the wheel cylinder 23 but to the stroke simulator 69. During the brake regeneration cooperative control, a differential pressure corresponding to the magnitude of the regenerative braking force acts between the upstream and downstream of the regulator cut valve 65 and the master cut valve 64.

  In the present embodiment, the generation or release of the braking request from the driver, that is, the start and end of the depression of the brake pedal 24 by the driver is determined by the control unit, that is, the brake ECU 70 based on the input from the sensor. When the brake-on condition is satisfied, the brake ECU 70 determines that the brake operation by the driver is started and a braking request is generated. When the brake-off condition is satisfied, the brake ECU 70 determines that the brake operation by the driver is released and the braking request is also released. Hereinafter, for the sake of convenience, the generation of a braking request is appropriately referred to as “braking on” and the cancellation of the braking request is appropriately referred to as “braking off”.

  From the viewpoint of improving the fail-safe property or realizing braking determination with higher accuracy, the brake ECU 70 determines braking on and braking off based on input signals from a plurality of sensors. Of course, the brake ECU 70 can make a determination based on the measurement value of a single sensor, and may do so.

  In the present embodiment, the control unit applies a first determination for determining the occurrence of a braking request based on a plurality of input signals including an input signal indicating a stroke, and a plurality of input signals including an input signal indicating a working hydraulic pressure. Based on this, a second determination is made to determine the occurrence of a braking request. The control unit sets a braking-on determination condition that at least one of the determination results of the first determination and the second determination indicates the occurrence of a braking request. In the first determination, the control unit determines that a braking request has been generated as a determination result of the first determination when all or a majority of the plurality of input signals including the input signal indicating the stroke indicate generation of the braking request. To do. In the second determination, the control unit generates a braking request as a determination result of the second determination when all or a majority of the plurality of input signals including the input signal indicating the hydraulic fluid pressure indicate the generation of the braking request. Shall.

  The input signal used by the control unit for each determination is typically a signal indicating a measurement value measured by a sensor such as a stroke sensor or a hydraulic pressure sensor, and is a signal input from the sensor to the control unit. However, it is not limited to this. Instead of a signal indicating the measured value from the sensor, it may be a signal that changes depending on whether the brake operation is on or off, such as an input signal from a stop lamp switch to the control unit. In the following, for convenience, the term “sensor” includes not only a so-called sensor but also means for inputting a signal that changes according to a brake operation to the control unit.

  In this way, the control unit determines that the brake is on when either of the determination results of the first determination or the second determination indicates that the brake is on, so that the brake-on trigger that generates the braking force is generated in the brake-by-wire. Fail-safety can be enhanced with respect to detection. By using both the first determination and the second determination, if any sensor used for one determination is abnormal, or even if it is not abnormal, the output value of the sensor cannot be trusted for a very short time due to the influence of noise or the like. Even if the state is a so-called invalid state, it is possible to detect braking on the basis of the other determination result. Further, an additional determination may be added to the first determination and the second determination described above to determine that the braking is on when any of the determination results indicates braking on. For example, any one of the three determination results May indicate that a braking request is generated as a braking-on determination condition.

  In each of the first determination and the second determination, it is concluded that braking is on when all or a majority of the plurality of input signals indicate braking on. Each of the first determination and the second determination is configured as a multiple system including a plurality of sensors. In each of the first determination and the second determination, the control unit typically determines based on two input signals. In this way, when all or a majority of the input signals in each judgment system indicate that braking is on, the judgment system judges that braking is on. Therefore, due to fluctuations in sensor values unrelated to braking on. The possibility of erroneously determining that braking is on can be reduced. Factors that cause fluctuations in the sensor value regardless of braking on include, for example, noise in the sensor value and changes in environmental temperature.

  Further, regarding the brake-off condition as well as the above-described brake-on condition, the control unit can use a plurality of determination systems configured as a multiplex system with a plurality of sensors. The control unit determines the release of the braking request based on a plurality of input signals including an input signal indicating a stroke, and cancels the braking request based on a plurality of input signals including an input signal indicating the hydraulic pressure. The fourth determination is performed. The control unit uses the determination result of the third determination and the fourth determination that both indicate the release of the braking request as a brake-off determination condition. In the third determination, when all or a majority of the plurality of input signals including the input signal indicating the stroke indicate release of the braking request, the control request is canceled as a determination result of the third determination. And In the fourth determination, the control unit cancels the braking request as the determination result of the fourth determination when all or a majority of the plurality of input signals including the input signal indicating the hydraulic fluid pressure indicate the cancellation of the braking request. Shall be.

  Further, in each of the third determination and the fourth determination, it is concluded that braking is off when any of the plurality of input signals indicates braking off. Each of the third determination and the fourth determination is configured as a multiple system including a plurality of sensors. In each of the third determination and the fourth determination, the control unit typically determines based on two input signals.

  The control unit may execute the first determination and the third determination based on an input signal from a common sensor, or make a combination of a plurality of sensors to be referred to differ between the first determination and the third determination. Also good. In addition, the control unit may execute the second determination and the fourth determination based on an input signal from a common sensor, and the combination of a plurality of sensors to be referred to is different between the second determination and the fourth determination. It may be allowed. When the first determination and the third determination are performed based on the input signal from the common sensor, and the second determination and the fourth determination are performed based on the input signal from the common sensor, braking is performed. The off condition is a negation of the brake on condition.

  More specifically, in this embodiment, the braking-on condition is set to use a stroke, a regulator pressure, and a wheel cylinder pressure. The brake ECU 70 determines whether or not the braking is on by using, for example, two measured values from the stroke sensor 25 as the first determination. It is assumed that the brake ECU 70 determines that the determination result of the first determination is braking on on condition that both of the two measured values from the stroke sensor 25 exceed a preset threshold value. Further, the brake ECU 70 determines whether or not the braking is on by using the measured values of the regulator pressure sensor 71 and the control pressure sensor 73, for example, as the second determination. The brake ECU 70 assumes that the determination result of the second determination is brake-on on the condition that the measured values of the regulator pressure sensor 71 and the control pressure sensor 73 both exceed a preset threshold value. The brake ECU 70 determines that the brake is on when at least one of the determination results of the first determination and the second determination indicates that the brake is on, and starts brake force control by brake-by-wire.

Here, for ease of understanding,
Condition A1: An input signal from one system of the stroke sensor 25 indicates braking on.
Condition A2: An input signal from the other system of the stroke sensor 25 indicates braking on.
Condition A3: The input signal from the regulator pressure sensor 71 indicates braking on.
Condition A4: The input signal from the control pressure sensor 73 indicates braking on.
In this case, the braking on condition of this embodiment is
(A1 and A2) or (A3 and A4)
Can be expressed as: In other words, the brake ECU 70 determines that braking is on when it is determined that braking is on based on the measured value of the stroke or when braking is determined on the basis of the hydraulic fluid pressure. Here, the expression “or” is not limited to the case where either “A1 and A2” or “A3 and A4” is satisfied, but both “A1 and A2” and “A3 and A4” are satisfied. Including the case of doing.

  Further, the brake-off condition is set so as to use the stroke, the regulator pressure, and the wheel cylinder pressure as in the brake-on condition. The brake ECU 70 determines whether or not the braking is off using, for example, two measured values from the stroke sensor 25 as the third determination. Assume that the brake ECU 70 determines that the determination result of the third determination is braking off on condition that at least one of the two measured values from the stroke sensor 25 falls below a preset threshold value. In the present embodiment, the stroke threshold value in the first determination and the third determination is set to the same value.

  As a fourth determination, the brake ECU 70 determines, for example, whether or not the braking is off using the measured values of the regulator pressure sensor 71 and the control pressure sensor 73. The brake ECU 70 determines that the determination result of the fourth determination is brake-off on condition that at least one of the measured values of the regulator pressure sensor 71 and the control pressure sensor 73 has fallen below a preset threshold value. In the present embodiment, the hydraulic pressure threshold values in the second determination and the fourth determination are set to the same value. The brake ECU 70 determines that the brake is off when both of the determination results of the third determination and the fourth determination indicate that the brake is off, and ends the brake control.

For ease of understanding, as well as the description of the braking on condition above,
Condition B1: An input signal from one system of the stroke sensor 25 indicates braking off.
Condition B2: An input signal from the other system of the stroke sensor 25 indicates braking off.
Condition B3: The input signal from the regulator pressure sensor 71 indicates braking off.
Condition B4: The input signal from the control pressure sensor 73 indicates braking off.
In this case, the brake-off condition of this embodiment is
(B1 or B2) and (B3 or B4)
Can be expressed as: When it is noted that the conditions B1 to B4 are negations of the conditions A1 to A4, it will be understood that the braking off condition of the present embodiment is the negation of the braking on condition. That is, in this embodiment, the brake-off condition is satisfied when the brake-on condition is not satisfied.

  In the present embodiment, a determination system for determining the generation and release of the braking request is constructed using the control pressure sensor 73 for measuring the wheel cylinder pressure. For this reason, the number of sensors mounted on the brake control device 20 can be reduced when a plurality of determination systems is constructed as a multiplex system from the viewpoint of fail-safety as described above. Specifically, it is possible to omit the hydraulic pressure sensor that is arranged on the master side so as to be paired with the regulator pressure sensor 71 and directly measures the master cylinder pressure. This is preferable in that the wiring in the brake control system can be simplified and the system can be downsized, and the cost can be reduced.

  Since the master cylinder unit 27 according to the present embodiment is a master cylinder with a hydraulic pressure booster, the wheel cylinder pressure is relatively likely to increase when the driver operates the brake. Therefore, even when the wheel cylinder pressure is used for the brake on condition or the brake off condition, it is possible to determine whether the brake is on or off with good accuracy.

  Note that the determination threshold for each sensor may be different depending on the braking-on condition and the braking-off condition. For example, in the above-described embodiment, the hydraulic pressure threshold values in the second determination and the fourth determination are set to the same value, but may be set to different values. The hydraulic pressure threshold value in the fourth determination may be set higher than the hydraulic pressure threshold value in the second determination. In this way, even if there is a delay in the hydraulic pressure response at the time of braking off, for example, the hydraulic pressure threshold value in the fourth determination is set high, so that the braking off condition is satisfied. Can reduce the delay.

  The arrangement of the regulator pressure sensor 71 and the control pressure sensor 73 in the present embodiment is preferable in that the number of hydraulic pressure sensors to be mounted on the brake control device 20 in order to configure the system can be minimized. .

  As described above, the brake control device 20 includes a front system that connects the master cylinder unit 27 and the front wheel side wheel cylinders 23FL and 23FR, and a rear system that connects the master cylinder unit 27 and the rear wheel side wheel cylinders 23RL and 23RR. The main flow path 45 which connects a system | strain, a front system | strain, and a rear system | strain and is provided with the separation valve 60 in the middle is provided. The front system and the rear system are each provided with a cut valve for controlling the flow of hydraulic fluid between the master cylinder unit 27 and each wheel cylinder 23, specifically, a master cut valve 64 and a regulator cut valve 65. A wheel cylinder pressure control system for controlling the wheel cylinder pressure in common when the separation valve 60 is opened is provided in parallel to the front system and the rear system.

  Under such an overall configuration, the brake control device 20 includes a wheel cylinder pressure sensor such as a control pressure sensor 73 disposed on the wheel cylinder side of the cut valve provided in the front system. Further, the brake control device 20 includes a hydraulic pressure source pressure sensor such as a regulator pressure sensor 71 disposed on the master cylinder unit side of the cut valve provided in the rear system. The brake control device 20 according to the present embodiment includes only three of a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 as hydraulic pressure sensors.

  The wheel cylinder pressure sensor arranged in the front system can measure the wheel cylinder pressure that is commonly controlled when the separation valve 60 is in the open state. In addition, even when the front system and the rear system are separated by closing the separation valve 60, the wheel cylinder pressure sensor can surely know the wheel cylinder pressure on the front wheel side that generally contributes to braking. Become.

  On the other hand, the hydraulic pressure in the master cylinder unit 27, that is, the master cylinder pressure and the regulator pressure can be measured by a hydraulic pressure source pressure sensor arranged in the rear system. Further, when the front system and the rear system are separated by closing the separation valve 60, the hydraulic pressure of the rear system can be known.

  By arranging such hydraulic pressure sensors, it is possible to construct a brake system with the minimum number of hydraulic pressure sensors. Thereby, simplification of wiring in the brake control system and miniaturization of the system are realized, and the cost can be reduced.

  Next, a first modification of the present embodiment will be described. This modification is a modification related to the above-described second determination and fourth determination using hydraulic fluid pressure. In this modification, the control unit uses an input signal indicating the wheel cylinder pressure and an input signal from the stop lamp switch 80 in combination. The control unit selectively uses the input signal indicating the wheel cylinder pressure and the input signal from the stop lamp switch 80 when determining the braking on.

  This first modification is effective for a brake system having no booster mechanism and a brake system having a relatively large brake caliper, that is, a wheel cylinder volume. In these brake systems, the wheel cylinder pressure is relatively less likely to increase with respect to the driver's brake operation. In contrast, the master cylinder pressure and the regulator pressure are relatively easy to increase because the master cut valve 64 and the regulator cut valve 65 function as orifices.

  In this modification, the brake ECU 70 determines whether the input signal from at least one of the control pressure sensor 73 and the stop lamp switch 80 indicates braking on, and the input signal from the regulator pressure sensor 71 indicates braking on. Suppose that the determination result of 2 determination is braking on. The brake ECU 70 determines the fourth determination when the input signals from both the control pressure sensor 73 and the stop lamp switch 80 indicate braking off, or when the input signal from the regulator pressure sensor 71 indicates braking off. Suppose the result is braking off. Note that the input signal from the stop lamp switch 80 indicates braking on means that the stop lamp should be turned on specifically, and the input signal from the stop lamp switch 80 indicates braking off. Specifically, this means that the stop lamp should be turned off.

Here, in order to facilitate the understanding as described above,
Condition A5: The input signal from the stop lamp switch 80 indicates braking on.
Condition B5: The input signal from the stop lamp switch 80 indicates braking off.
If the notation, the brake-on condition and the brake-off condition of this modification are respectively
Braking on condition: (A1 and A2) or (A3 and (A4 or A5))
Braking off condition: (B1 or B2) and (B3 or (B4 and B5))
Can be expressed as: If it is noted that the condition B5 is a negative of the condition A5, it will be understood that the brake-off condition is also a negative of the brake-on condition in this modified example.

  In the first modification, an input signal having a higher response than the wheel cylinder pressure with respect to the driver's braking operation is used together with the input signal indicating the wheel cylinder pressure. As a result, even if a delay occurs in the response of the wheel cylinder pressure to the brake operation, the delay in the braking determination can be reduced. In particular, since the signal from the stop lamp switch 80 generally has a higher response than the wheel cylinder pressure to the driver's brake operation, it is effective to reduce the determination delay.

  Next, a second modification of the present embodiment will be described. In this modification, the control unit sets a condition different from the negation of the brake-on determination condition as the brake-off determination condition. The control unit varies the combination of sensors used to determine whether braking is on and the combination of sensors used to determine whether braking is off. For example, the control unit is set so that the wheel cylinder pressure is used for the brake-on determination condition and the wheel cylinder pressure is not used for the brake-off determination condition.

  In a brake-by-wire brake system, the wheel cylinder pressure may not be reduced immediately even when the driver releases his / her foot from the brake pedal 24 and releases the operation. In the present embodiment, for example, there may be a pressure reduction response delay in the pressure reduction linear control valve 67. Alternatively, there is a case where a pressure reduction response by the pressure reduction linear control valve 67 is intentionally generated in order to reduce an operation sound due to self-excited vibration or the like in the pressure reduction linear control valve 67. In these cases, there is a possibility that a time difference occurs between the release of the brake operation by the driver and the reduction of the wheel cylinder pressure, and the brake-off determination using the wheel cylinder pressure may be delayed. In particular, an abnormality may occur in the regulator pressure sensor 71, and there is a possibility that the brake-off determination may be delayed in a state where the detection of the reduction in the wheel cylinder pressure by the control pressure sensor 73 is essential.

  This second modification is a further modification related to the first modification described above. The second modified example is the same as the first modified example with respect to the braking on condition, and the braking off condition is different from that of the first modified example. The first modification and the second modification are different with respect to the fourth determination of the brake-off condition. In the brake-off condition according to the second modification, an input signal from the stop lamp switch is used instead of the wheel cylinder pressure. Specifically, the brake ECU 70 determines that the determination result of the fourth determination is braking off when the input signal from the stop lamp switch 80 indicates braking off or when the input signal from the regulator pressure sensor 71 indicates braking off. Suppose that

Here, if the notation for facilitating understanding is used in the same manner as described above, the braking on condition and the braking off condition according to the second modification example are respectively
Braking on condition: (A1 and A2) or (A3 and (A4 or A5))
Braking off condition: (B1 or B2) and (B3 or B5)
It becomes. It will be understood that the brake-off condition is set to a condition different from the negation of the brake-on condition.

  As described above, in the second modification, the brake-off is performed by using an input signal having a response higher than the wheel cylinder pressure when the driver releases the brake operation, specifically, for example, an input signal from a stop lamp switch. Is determined. Thus, instead of the wheel cylinder pressure, by using an input signal that changes immediately in response to the release of the brake operation, it is possible to quickly and successfully determine that the brake is off. Further, as long as the stop lamp switch is normal even when the regulator pressure sensor 71 is abnormal, it is possible to quickly determine braking OFF, so that braking determination with high fail-safe property is realized. Furthermore, it is possible to improve the degree of freedom in designing the intentional pressure reduction response delay of the pressure reducing linear control valve 67. Although the fourth determination is an example in which braking off is determined using the input signal from the stop lamp switch 80 and the input signal from the regulator pressure sensor 71, the fourth determination is performed from the stop lamp switch 80. It is also possible to make a determination based only on the input signal.

  According to the second modification, the brake-off condition is not simply set as a negation of the brake-on condition, but is set to a condition different from the negation of the brake-on determination condition. For this reason, the determination condition can be set in consideration of the difference in the amount of measurement object at the time of braking on and braking off, for example, the variation of hydraulic fluid pressure. Thereby, the presence or absence of the braking request | requirement from a driver | operator can be determined favorably.

  Here, it is possible to use the stroke sensor 25 instead of the stop lamp switch 80. However, when the determination system is constructed in a double manner by the determination system based on the stroke and the determination system based on the hydraulic pressure as in this embodiment, a sensor other than the stroke sensor 25 already incorporated in the determination system is used. It would be preferable.

It is a distribution diagram showing a brake control device concerning one embodiment of the present invention.

Explanation of symbols

  20 brake control device, 23 wheel cylinder, 24 brake pedal, 25 stroke sensor, 70 brake ECU, 71 regulator pressure sensor, 73 control pressure sensor, 80 stop lamp switch.

Claims (17)

  A control unit that determines that a braking request from the driver has occurred when the braking-on determination condition is satisfied, and determines that the braking request from the driver has been canceled when the braking-off determination condition is satisfied A brake control device comprising:   The brake control device according to claim 1, wherein the control unit sets a condition different from the negation of the braking on determination condition as the braking off determination condition.   3. The brake according to claim 2, wherein the control unit is set to use a wheel cylinder pressure for the brake-on determination condition and not to use a wheel cylinder pressure for the brake-off determination condition. Control device.   4. The brake control device according to claim 3, wherein the control unit determines braking-off based on an input signal having a response higher than the wheel cylinder pressure with respect to the release of the brake operation by the driver.   The brake control device according to claim 4, wherein the control unit determines braking off based on an input signal from a stop lamp switch.   The brake control device according to claim 1, wherein the control unit sets negation of the braking on determination condition as the braking off determination condition.   The controller determines a first determination for determining the occurrence of the braking request based on a plurality of input signals including an input signal indicating a pedal stroke, and determines the generation of the braking request based on an input signal indicating the hydraulic pressure. A second determination to determine the release of the braking request based on a plurality of input signals including an input signal indicating the pedal stroke, and the braking request based on the input signal indicating the hydraulic pressure. The brake control device according to claim 1, wherein a fourth determination for determining release is performed. The braking-on determination condition is satisfied when at least one of the determination results of the first determination and the second determination indicates the occurrence of the braking request,
The brake control device according to claim 7, wherein the brake-off determination condition is satisfied when both of the determination results of the third determination and the fourth determination indicate that the braking request is released. In the first determination, when all or a majority of the plurality of input signals including the input signal indicating the pedal stroke indicate generation of a braking request, the control unit determines the determination result of the first determination as the determination result of the first determination. Assume that a braking request has occurred,
In the second determination, when all or a majority of the plurality of input signals including the input signal indicating the hydraulic fluid pressure indicate generation of the braking request, the braking request is determined as a determination result of the second determination. As it occurred,
In the third determination, when all or a majority of the plurality of input signals including the input signal indicating the pedal stroke indicate cancellation of the braking request, the braking request is canceled as a determination result of the third determination. And
In the fourth determination, when all or a majority of the plurality of input signals including the input signal indicating the hydraulic pressure indicate release of the braking request, the braking request is determined as a determination result of the fourth determination. The brake control device according to claim 7, wherein the brake control device is released. In the first determination, the occurrence of the braking request is determined using two measured values from a stroke sensor,
In the second determination, the occurrence of the braking request is determined using the measured values of the regulator pressure sensor and the control pressure sensor,
The third determination determines cancellation of the braking request using two measured values from the stroke sensor,
The brake control device according to claim 7, wherein the fourth determination determines whether to release the braking request by using measured values of the regulator pressure sensor and the control pressure sensor. When the input signal from at least one of the control pressure sensor and the stop lamp switch indicates braking on and the input signal from the regulator pressure sensor indicates braking on, the control unit displays the determination result of the second determination as the braking result. Suppose that a request occurs,
When the input signals from both the control pressure sensor and the stop lamp switch indicate braking off, or when the input signal from the regulator pressure sensor indicates braking off, the determination result of the fourth determination is determined as the braking request. The brake control device according to claim 7, wherein the brake control device is released.   When the braking on determination condition is satisfied, it is determined that a braking request from the driver has occurred, and when the braking off determination condition is satisfied, it is determined that the braking request from the driver has been canceled. Brake control method characterized.   The brake control method according to claim 12, wherein the brake-off determination condition is a condition different from the negation of the brake-on determination condition.   14. The brake control method according to claim 13, wherein a wheel cylinder pressure is used for the brake-on determination condition, and a wheel cylinder pressure is not used for the brake-off determination condition.   The brake control method according to claim 14, wherein braking-off is determined based on an input signal having a response higher than the wheel cylinder pressure with respect to release of the brake operation by the driver.   The brake control method according to claim 15, wherein braking off is determined based on an input signal from a stop lamp switch.   The brake control method according to claim 12, wherein the brake-off determination condition is negative of the brake-on determination condition.

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