JP2010036626A - Sensor abnormality determination device and sensor abnormality determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a determination of abnormality of a stroke sensor with high accuracy. <P>SOLUTION: In a sensor abnormality determination device, a brake ECU performs a zero-point correction on a position of a brake pedal when it is not operated using a first detection value detected by a first stroke sensor or a second detection value detected by a second stroke sensor. An EEPROM stores therein a first variance profile indicative of a correspondence between the first detection value and its variance and a second variance profile indicative of a correspondence between the second detection value and its variance. The brake ECU determines whether the second detection value detected immediately after performing the zero-point correction is out of a variation range in which the second detection value should be included using the first detection value, the first variance profile, and the second variance profile detected immediately after performing the zero-point correction, and determines that the abnormality has occurred to the first stroke sensor or the second stroke sensor when the second detection value is out of the variation range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor abnormality determination technique, and more particularly to a sensor abnormality determination technique for determining whether or not an abnormality has occurred in a stroke sensor that detects a detection value corresponding to an operation amount of a brake pedal.

  Currently, development of an electronically controlled brake system that generates an optimal braking force by electronic control is actively underway. In such an electronically controlled brake system, a braking request by a driver is acquired based on a brake pedal depression amount and a master cylinder pressure, and a target wheel cylinder pressure to be applied to each wheel is calculated based on the brake request. For this reason, highly accurate detection of the operation amount of the brake pedal is extremely important in realizing safe and comfortable traveling of the vehicle.

Here, for example, when the difference between the detection values of the two stroke sensors is within a predetermined range and the detection value of the two stroke sensors is smaller than a reference value based on the master cylinder pressure, either the master cylinder pressure sensor or the stroke sensor is used. An abnormality determination device that determines whether an abnormality has occurred has been proposed (see, for example, Patent Document 1).
JP-A-11-301463

  For example, the deviation characteristics of the stroke sensor fluctuate due to temperature changes. For this reason, it is necessary to make a determination with a certain margin in order to avoid the determination of an abnormality despite being normal. However, if the determination is made with a margin in this way, the determination accuracy decreases. In particular, for example, a non-contact type stroke sensor has a complicated structure and various variations in deviation characteristics. Therefore, it is difficult to predict abnormality of the stroke sensor and perform abnormality determination of the stroke sensor.

  The present invention has been made in view of these problems, and an object thereof is to realize an abnormality determination of a highly accurate stroke sensor.

  In order to solve the above problems, a sensor abnormality determination device according to an aspect of the present invention includes a first stroke sensor that detects a first detection value corresponding to an operation amount of a brake pedal, and a first stroke sensor that corresponds to an operation amount of the brake pedal. A second stroke sensor for detecting two detection values, and zero point correction means for performing zero point correction on the position of the brake pedal when not operated by using the first detection value or the second detection value , An abnormality determining means for determining whether an abnormality has occurred in the first stroke sensor or the second stroke sensor, a first deviation characteristic indicating a correspondence between the first detection value and the deviation, and a second detection value and the deviation Storage means for holding a second deviation characteristic indicating a correspondence with the first deviation characteristic. The abnormality determination means uses the first detection value, the first deviation characteristic, and the second deviation characteristic that are detected immediately after the zero point correction is performed, and the second detection value that is detected immediately after the zero point correction is performed. Is determined to be outside the variation range that should fall within the range, and when the second detection value is outside the variation range, it is determined that an abnormality has occurred in the first stroke sensor or the second stroke sensor.

  According to this aspect, by performing the zero point correction, it is possible to remove a deviation that may vary. For this reason, abnormality determination can be performed using the inherent deviation of the stroke sensor, and highly accurate abnormality determination can be realized.

  The abnormality determining means refers to the first deviation characteristic, estimates the brake pedal operation amount range based on the first detection value detected immediately after the zero point correction and the deviation, and refers to the second deviation characteristic. , Estimating a variation range within which the second detection value should fall based on the estimated brake pedal operation range, and determining whether the second detection value immediately after execution of the zero point correction is within the estimated variation range Then, when the second detection value is outside the estimated variation range, it may be determined that an abnormality has occurred in the first stroke sensor or the second stroke sensor.

  According to this aspect, it is possible to accurately estimate the fluctuation range in which the second detection value should fall. For this reason, a highly accurate abnormality determination can be realized.

  The zero point correction means is configured to detect the first position and the first position of the brake pedal when one of the first position of the brake pedal calculated based on the first detection value and the second position of the brake pedal calculated based on the second detection value satisfies the correction condition. Zero point correction may be performed for both of the second positions.

  According to this aspect, the zero point correction can be performed also on the first position and the second position that do not satisfy the correction condition. For this reason, it is possible to accurately determine the stroke sensor abnormality to be executed next.

  The first stroke sensor or the second stroke sensor may be a non-contact sensor.

  According to this aspect, even in a non-contact type sensor, it is possible to perform stroke sensor abnormality determination by removing characteristic variations of the stroke sensor that are difficult to predict by executing zero point correction. For this reason, the stroke sensor abnormality determination can be executed with high accuracy.

  The first stroke sensor and the second stroke sensor may have a gain set to match different brake pedal structures.

  According to this aspect, for example, when the first stroke sensor is adapted to the first brake pedal structure, the first stroke sensor is used for braking control, and the second stroke sensor is used for stroke sensor abnormality determination. it can. Further, for example, when the second stroke sensor is adapted to the second brake pedal structure, the second stroke sensor can be used for braking control and the first stroke sensor can be used for stroke sensor abnormality determination. For this reason, the combination of a 1st stroke sensor and a 2nd stroke sensor can be used in common with multiple types of brake pedal structures, and the cost reduction by the number of parts reduction is realizable.

  Another aspect of the present invention is a sensor abnormality determination method. In this method, whether or not an abnormality has occurred in the first stroke sensor that detects the first detection value according to the operation amount of the brake pedal or the second stroke sensor that detects the second detection value according to the operation amount of the brake pedal. In the sensor abnormality determination method for determining whether the brake pedal is not operated, the first point detection value or the second detection value is used to perform zero point correction on the position of the brake pedal when not operated, and execution of zero point correction Using the first detection value detected immediately after, the first deviation characteristic indicating the correspondence between the first detection value and the deviation, and the second deviation characteristic indicating the correspondence between the second detection value and the deviation, A step of determining whether or not the second detection value detected immediately after execution of the zero point correction is out of a variation range to be accommodated; and when the second detection value is out of the variation range, Comprising determining that an abnormality in the two-stroke sensor occurs, the.

  According to this aspect, by performing the zero point correction, it is possible to remove a deviation that may vary. For this reason, abnormality determination can be performed using the inherent correspondence between the detection value and deviation of the stroke sensor, and highly accurate abnormality determination can be realized.

  According to the present invention, it is possible to realize an abnormality determination of a highly accurate stroke sensor.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a system diagram showing a braking control device 20 according to the first embodiment. A braking 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 braking control device 20 according to the first 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 electrical energy and hydraulic braking by the braking control device 20 can be used for braking the vehicle. The vehicle in the first embodiment can execute the 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 braking 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 first embodiment applies the brake fluid pressurized according to the operation amount by the driver of the brake pedal 24 as the brake operation member to the disc brake units 21FR to 21RL. And send it out. 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. Although the disc brake units 21FR to 21RL are used in the first embodiment, other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In the first 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. The brake pedal 24 employs a so-called single pedal type brake structure. Of course, other pedal structures may be employed for the brake pedal 24, and for example, a link pedal type brake pedal structure may be employed. 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 master cylinder 32 and the regulator 33 have a so-called idle stroke. The idle stroke is a stroke from when the brake operation is not performed until the brake pedal 24 is depressed and the connection between the master cylinder 32 and the regulator 33 and the reservoir 34 is cut off. During the idle stroke, the fluid pressure in the master cylinder 32 and the regulator 33 does not increase because the reservoir 34 is in communication. The master cylinder unit 27 of the first embodiment is configured such that when the brake pedal is depressed, the idle stroke of the regulator 33 is first reduced as the stroke increases, and then the idle stroke of the master cylinder 32 is reduced. That is, the connection with the reservoir 34 is cut off in the order of the regulator 33 and the master cylinder 32.

  Hereinafter, for the sake of convenience, the pedal stroke when the connection between the regulator 33 and the reservoir 34 is cut off is referred to as a first cut-off stroke, and the stroke when the connection between the master cylinder 32 and the reservoir 34 is cut off is referred to as a second cut-off stroke. Called. In the first embodiment, the second cutoff stroke is larger than the first cutoff stroke. When the pedal stroke is between the first cutoff stroke and the second cutoff stroke, the regulator 33 has a higher pressure than the master cylinder 32 and a differential pressure is generated between the two hydraulic fluid chambers. This is because the regulator 33 is disconnected from the reservoir 34 and the hydraulic fluid is pressurized according to the stroke, whereas the master cylinder 32 is connected to the reservoir 34 and the hydraulic pressure does not increase.

  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 pressure is maintained within a set range to be maintained by the pump 36 (this may be referred to as an allowable range in the present specification). Based on the measurement value of the accumulator pressure sensor 72, the brake ECU 70 turns on the pump 36 to increase the accumulator pressure when the accumulator pressure falls below the lower limit of the allowable range, and when the accumulator pressure exceeds the upper limit of the allowable range. The pressurization is finished by turning off the pump 36.

  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 ON / OFF controlled, and the valve closing 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 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. In other words, in the first embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common controls for controlling the supply and discharge of the working fluid delivered from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as a control valve. Thus, if the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are made common to the wheel cylinders 23, it is preferable from the viewpoint of cost as compared to providing a linear control valve 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 braking 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 first 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 sensors connected to the brake ECU 70 include a first stroke sensor 25A and a second stroke sensor 25B provided on the brake pedal 24. The first stroke sensor 25A and the second stroke sensor 25B detect a pedal stroke as an operation amount of the brake pedal 24 and give a signal indicating the detected value to the brake ECU 70. In the braking control device 20, the detected value by the first stroke sensor 25A is used for braking control for controlling the wheel cylinder pressure. Further, the detection value by the second stroke sensor 25B is used for stroke sensor abnormality determination as to whether or not an abnormality has occurred in the first stroke sensor 25A or the second stroke sensor 25B.

  Further, a stop lamp switch is connected to the brake ECU 70. The stop lamp switch is turned on when the brake pedal 24 is depressed. As a result, the stop lamp is turned on. When the depression of the brake pedal 24 is released, the stop lamp switch is turned off and the stop lamp is turned off. A signal indicating the lighting state of the stop lamp switch is input from the stop lamp switch to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70.

  The braking control device 20 configured as described above can execute brake regeneration cooperative control. The braking control device 20 receives the braking request and starts braking. 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 that should be generated by the braking control device 20 by subtracting the regenerative braking force from the required braking force. Here, the effective value of the braking force due to regeneration is supplied from the hybrid ECU to the braking 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 each wheel cylinder 23 via the pressure-increasing linear control valve 66, and a 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 first 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. A so-called brake-by-wire braking force control 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. The braking control device 20 according to the first embodiment naturally controls the braking force by the wheel cylinder pressure control system even when the required braking force is provided only by the hydraulic braking force without using the regenerative braking force. Can do.

  When brake-by-wire braking force control is performed, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid delivered 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. The brake ECU 70 opens the separation valve 60. Thereby, each wheel cylinder pressure is controlled to a common hydraulic pressure.

  When the brake pedal 24 is depressed, the brake ECU 70 uses the detection results of the stroke sensor 25 and the control pressure sensor 73 to start calculating the target wheel cylinder pressure. The brake ECU 70 controls the hydraulic actuator 40 to increase or decrease the wheel cylinder pressure so as to realize the calculated target wheel cylinder pressure. Therefore, the brake ECU 70 functions as a wheel cylinder pressure control unit that controls the hydraulic actuator to increase or decrease the wheel cylinder pressure.

  In the electronically controlled brake, the required accuracy of the stroke sensor for setting the driver's brake feeling is very high. For this reason, the stroke sensor alone may not satisfy the accuracy. In such a case, it is necessary to satisfactorily set the brake feeling in the entire brake system including the brake ECU 70.

  Here, since the contact-type stroke sensor generally detects the operation amount of the stroke sensor by a variable resistance, the structure is simple and there are few types of failure modes. In addition, since the variation of the deviation characteristic due to the temperature change is simple, it is possible to predict the variation and execute the abnormality determination of the stroke sensor.

  On the other hand, the non-contact type stroke sensor employed as the first stroke sensor 25A and the second stroke sensor 25B has a complicated structure because it requires a complicated electric circuit using a hall element or the like. For this reason, the types of failure modes generally increase, and the deviation characteristics change in a complicated manner even with temperature changes. Therefore, in order to avoid the influence on the brake feeling, it is necessary to reliably detect an abnormality corresponding to such various failure modes and temperature changes.

  Currently, brake pedal structures such as a single pedal type and a link pedal type are known. In the first embodiment, a single-pedal brake structure is employed. Since single pedal type and link pedal type brake pedal structures are known, the description thereof will be omitted. Thus, when the brake pedal structure is different, the detection range for detecting the operation amount of the brake pedal is usually different. However, it is preferable that the number of component types is small from the viewpoint of cost reduction.

  Hereinafter, the abnormality determination control of the first stroke sensor 25A and the second stroke sensor 25B will be described in detail with reference to the flowchart shown in FIG.

  FIG. 2 is a flowchart showing in detail the execution procedure of the stroke sensor abnormality determination control according to the first embodiment. The processing in this flowchart starts when the ignition switch of the vehicle is turned on, and is repeatedly executed every predetermined time until the ignition switch is turned off.

  The brake ECU 70 has an EEPROM (Electrically Erasable and Programmable Read Only Memory) (not shown) as storage means. The brake ECU 70 determines whether or not the zero point correction of the first stroke sensor 25A and the second stroke sensor 25B has been executed by determining whether or not the EEPROM has been initialized (S10). When the zero point correction has not been executed (N in S10), the brake ECU 70 determines whether or not the first abnormality determination condition is satisfied (S22).

  In the first embodiment, when no abnormality has occurred in both the first stroke sensor 25A and the second stroke sensor 25B, the sum of the detection value V1 of the first stroke sensor 25A and the detection value V2 of the second stroke sensor 25B. Is theoretically the control voltage V0. Using this, the brake ECU 70 determines that an abnormality has occurred in either the first stroke sensor 25A or the second stroke sensor 25B when the difference between the sum of V1 and V2 and V0 exceeds a predetermined ratio of V0. judge. This is expressed by the following formula. This is the first abnormality determination condition.

| V0− (V1 + V2) | ≧ αV0
When the first abnormality determination condition is not satisfied (N in S22), the processing in this flowchart is temporarily ended. When the first abnormality determination condition is satisfied (Y in S22), it is determined that an abnormality has occurred in the first stroke sensor or the second stroke sensor, and the brake ECU 70 executes error processing (S20).

  Specifically, the brake ECU 70 cancels the electronic control of the wheel cylinder pressure in the error processing, and opens the regulator cut valve 65 and the master cut valve 64 so that the depression force of the brake pedal 24 directly increases the wheel cylinder pressure. Let Such error processing is well known and will not be described. In this manner, the brake ECU 70 functions as an abnormality determination unit that determines whether an abnormality has occurred in the first stroke sensor 25A or the second stroke sensor 25B.

  In the present embodiment, error processing is executed when the first abnormal condition is continuously satisfied for a predetermined time. Specifically, the brake ECU 70 starts measuring time when the first abnormal condition is first satisfied, and then satisfies the first abnormal condition continuously for a predetermined time when the first abnormal condition is satisfied again. Determine whether or not. Thus, the brake ECU 70 executes error processing when the first abnormal condition is continuously satisfied for a predetermined time.

  When it is determined that the zero point correction has been executed (Y in S10), the brake ECU 70 determines whether or not the brake pedal 24 is at an off point (S12). Here, the off point of the brake pedal 24 refers to the position of the brake pedal 24 that is recognized as not being depressed. The brake ECU 70 determines whether or not the brake pedal 24 is at the off point by using detection results of the regulator pressure sensor 71 and a wheel speed sensor (not shown). Since it is known whether or not the brake pedal 24 is at the off point, further detailed description is omitted. When the brake pedal 24 is not at the off point (N in S12), the processing in this flowchart is temporarily ended.

  The brake ECU 70 has a power supply circuit (not shown). The power supply circuit converts an input voltage of 12V into a control voltage of 5V and supplies it to the first stroke sensor 25A and the second stroke sensor 25B. Each of the first stroke sensor 25 </ b> A and the second stroke sensor 25 </ b> B detects an operation amount of the brake pedal 24 and outputs an analog output to the brake ECU 70. The power supply circuit also supplies a control voltage to the CPU. The CPU calculates a value obtained by dividing the first detection voltage input from the first stroke sensor 25A by the control voltage. This value is defined as a first detection value X1 detected by the first stroke sensor 25A. Further, the CPU calculates a value obtained by dividing the second detection voltage input from the second stroke sensor 25B by the control voltage. This value is set as a second detection value X2 detected by the second stroke sensor 25B.

  When the brake pedal 24 is at the off point (Y in S12), the brake ECU 70 determines the position of the brake pedal 24 calculated from the first detection value X1 (hereinafter referred to as “first position”) or the second detection value X2. It is determined whether or not the calculated position of the brake pedal 24 (hereinafter referred to as “second position”) is more than the reference operation amount Lref from the zero point corrected by the previous zero point correction (S14). When both the first position and the second position are closer to the reference operation amount Lref from the zero point (N in S14), the processing in this flowchart is temporarily ended.

  When the first position or the second position is away from the zero point by the reference operation amount Lref or more (Y in S14), the brake ECU 70 executes zero point correction (S16). Specifically, the brake ECU 70 executes zero point correction by setting the position of the brake pedal 24 at that time to zero.

  In this way, the brake ECU 70 performs zero point correction on the position of the brake pedal when not being operated, using the first detection value X1 or the second detection value X2. Therefore, the brake ECU 70 functions as a zero point correction unit for the brake pedal 24. Thereby, for example, even when a variation in the deviation of the first stroke sensor 25A and the second stroke sensor 25B due to a temperature change occurs, such a deviation can be removed.

  Note that the brake ECU 70 corrects the zero point with respect to both the first position and the second position even when one of the first position and the second position is away from the zero point by the reference operation amount Lref. Execute. As a result, it is possible to reliably remove variations in deviations of the first stroke sensor 25A and the second stroke sensor 25B due to temperature changes and the like.

  When the zero point correction is executed, the brake ECU 70 determines that the first detection value X1 or the second detection value X2 detected immediately after the execution of the zero point correction is both the first detection value X1 and the second detection value X2. It is determined whether or not a second abnormality determination condition based on the deviation is satisfied (S18). When the second abnormality determination condition is not satisfied (N in S18), the processing in this flowchart is temporarily ended. When the second abnormality determination condition is satisfied (Y in S18), it is determined that an abnormality has occurred in the first stroke sensor or the second stroke sensor, and the brake ECU 70 executes error processing (S20).

  In the present embodiment, error processing is executed when the second abnormal condition is continuously satisfied for a predetermined time. Specifically, the brake ECU 70 starts time measurement when the second abnormal condition is first satisfied, and whether the second abnormal condition is satisfied continuously for a predetermined time when the second abnormal condition is satisfied again after that. Determine whether or not. Thus, the brake ECU 70 executes error processing when the second abnormal condition is continuously satisfied for a predetermined time.

  Hereinafter, the second abnormality determination condition will be described with reference to FIGS. 3 (a), 3 (b), and 4.

  FIG. 3A is a diagram showing the deviation characteristics of the first stroke sensor 25A before execution of zero point correction, and FIG. 3B is the deviation characteristics of the first stroke sensor 25A after execution of zero point correction. FIG. 3A and 3B, θa on the horizontal axis indicates the sensor arm rotation angle.

  As shown in FIG. 3A, before the zero point correction is executed, the deviation of the first stroke sensor 25A, that is, the difference between the deviation upper limit D1 and the deviation lower limit D2 increases as the sensor arm rotation angle θa increases. However, before the zero point correction is executed, the R portion shown in FIG. 3A of the difference between the deviation upper limit D1 and the deviation lower limit D2 is a deviation that varies depending on a variation factor such as temperature. Hereinafter, this portion is referred to as a variation deviation R.

  After the zero point correction is executed, the fluctuation deviation R can be removed as shown in FIG. 3B, and only the deviation inherent to the first stroke sensor 25A can be largely left. Such inherent deviation can be obtained experimentally in advance. Hereinafter, a deviation characteristic unique to the first stroke sensor 25A is referred to as a first deviation characteristic, and a deviation characteristic unique to the second stroke sensor 25B is referred to as a second deviation characteristic. The EEPROM of the brake ECU 70 stores the first deviation characteristic and the second deviation characteristic acquired in advance as described above.

  FIG. 4 is a diagram illustrating the stroke sensor characteristics of the first stroke sensor 25A and the second stroke sensor 25B. In FIG. 4, the stroke sensor characteristic of the first stroke sensor 25A is shown as a first stroke sensor characteristic L1, and the stroke sensor characteristic of the second stroke sensor 25B is shown as a second stroke sensor characteristic L2.

  The first stroke sensor characteristic L1 indicates the correspondence between the operation amount θs and the first detection value X1, and the second stroke sensor characteristic L2 indicates the correspondence between the operation amount θs and the second detection value X2. The upper limit and lower limit of the deviation in the first stroke sensor characteristic L1 are calculated based on the first deviation characteristic, and are shown as a first deviation upper limit line La and a first deviation lower limit line Lb in FIG. Further, the upper limit and lower limit of the deviation in the second stroke sensor characteristic L2 are calculated based on the second deviation characteristic, and are shown as the second deviation upper limit line Lc and the second deviation lower limit line Ld in FIG.

  First, the brake ECU 70 refers to the first deviation characteristic held in the EEPROM, and estimates the operation amount range of the brake pedal 24 based on the first detection value X1 detected immediately after execution of the zero point correction and the deviation. Specifically, as shown in FIG. 4, the brake ECU 70 calculates the brake pedal operation amount θs at the intersection of the straight line “detection value X = first detection value X1” and the first deviation upper limit line La. This is the estimated minimum operation amount θsmin. Further, as shown in FIG. 4, the brake ECU 70 calculates the brake pedal operation amount θs at the intersection of the straight line “detection value X = first detection value X1” and the first deviation lower limit line Lb. This is the estimated maximum manipulated variable θsmax. The range from the estimated minimum operation amount θsmin to the estimated maximum operation amount θsmax is the operation amount range of the brake pedal 24 estimated from the first detection value X1.

  Next, the brake ECU 70 refers to the second deviation characteristic held in the EEPROM, and estimates the variation range Xv in which the second detection value X2 should be accommodated based on the estimated operation range of the brake pedal. Specifically, as shown in FIG. 4, the brake ECU 70 calculates a detected value X of an intersection point between the straight line “brake pedal operation amount θs = estimated minimum operation amount θsmin” and the second deviation upper limit line Lc. This is defined as an estimated maximum detected value Xmax. Further, as shown in FIG. 4, the brake ECU 70 calculates a detected value X of an intersection point between the straight line “brake pedal operation amount θs = estimated maximum operation amount θsmax” and the second deviation lower limit line Ld. This is assumed to be the estimated minimum detection value Xmin. A range between the estimated minimum detection value Xmin and the estimated maximum detection value Xmax is a variation range Xv in which the second detection value X2 should fall.

  The brake ECU 70 determines whether or not the second detection value X2 immediately after execution of the zero point correction is outside the variation range Xv in which the second detection value X2 should fall. When the second detection value X2 immediately after execution of the zero point correction is outside the variation range Xv, the brake ECU 70 determines that an abnormality has occurred in the first stroke sensor 25A or the second stroke sensor 25B, assuming that the abnormality determination condition is satisfied. To do. When the second detection value X2 immediately after execution of the zero point correction is within the variation range Xv, the brake ECU 70 determines that the first stroke sensor 25A and the second stroke sensor 25B are normal because the abnormality determination condition is not satisfied.

  As described above, the brake ECU 70 determines whether the first detection value X1 or the second detection value X2 detected immediately after the zero point correction is performed is based on the deviation between both the first detection value X1 and the second detection value X2. When the two abnormality determination conditions are satisfied, it is determined that an abnormality has occurred in the first stroke sensor 25A or the second stroke sensor 25B. Accordingly, it is possible to reliably detect an abnormality in the first stroke sensor 25A or the second stroke sensor 25B in response to various failure modes associated with employing a non-contact type stroke sensor. Further, by correcting the zero point, it is possible to remove a variation in deviation due to, for example, a temperature change, so that it is possible to set the brake feeling well.

  It should be noted that a map in which the variation range of the second detection value X2 that should be accommodated with respect to the first detection value X1 is stored in the ROM of the brake ECU 70, instead of the line relationship as shown in FIG. Good. The brake ECU 70 refers to this map to determine whether or not the second detection value X2 immediately after execution of the zero point correction is within a variation range that should be within the range. It may be determined that an abnormality has occurred in either the first stroke sensor 25A or the second stroke sensor 25B.

(Second Embodiment)
FIG. 5 is a diagram illustrating gain characteristics of the first stroke sensor 25A and the second stroke sensor 25B of the braking control apparatus 20 according to the second embodiment. The braking control device 20 according to the second embodiment has the same configuration as the braking control device 20 according to the first embodiment except for the gain characteristics of the first stroke sensor 25A and the second stroke sensor 25B.

  The first stroke sensor 25 </ b> A and the second stroke sensor 25 </ b> B have gains set to match different brake pedal structures. In the second embodiment, the first stroke sensor 25A has a gain characteristic suitable for a single pedal type brake pedal structure, and the second stroke sensor 25B has a gain characteristic suitable for a link pedal type brake pedal structure. is doing.

  Also in the second embodiment, the brake control device 20 employs a single pedal brake pedal structure. For this reason, the detected value by the first stroke sensor 25A is used for braking control for controlling the wheel cylinder pressure. Further, the detection value by the second stroke sensor 25B is used for stroke sensor abnormality determination as to whether or not an abnormality has occurred in the first stroke sensor 25A or the second stroke sensor 25B.

  Thus, when the gains of the first stroke sensor 25A and the second stroke sensor 25B are set, for example, when a single-pedal brake pedal structure is employed as in the second embodiment, the first The first stroke sensor 25A can be used for braking control, and the second stroke sensor 25B can be used for abnormality determination. On the other hand, for example, when a link pedal type brake pedal structure is employed in the braking control device 20, the second stroke sensor 25B can be used for braking control and the first stroke sensor 25A can be used for abnormality determination. Therefore, the combination of the first stroke sensor 25A and the second stroke sensor 25B can be used in common for a plurality of types of brake pedal structures while ensuring the accuracy of both braking control and abnormality determination, and the number of parts can be reduced. Cost reduction due to

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention.

It is a systematic diagram showing a braking control device concerning a 1st embodiment. It is a flowchart which shows in detail the execution procedure of the stroke sensor abnormality determination control which concerns on 1st Embodiment. (A) is a figure which shows the deviation characteristic of the 1st stroke sensor before zero point correction execution, (b) is a figure which shows the deviation characteristic of the 1st stroke sensor after zero point correction execution. It is a figure which shows the stroke sensor characteristic of a 1st stroke sensor and a 2nd stroke sensor. It is a figure which shows the gain characteristic of the 1st stroke sensor of the braking control apparatus which concerns on 2nd Embodiment, and a 2nd stroke sensor.

Explanation of symbols

  20 brake control device, 24 brake pedal, 25A first stroke sensor, 25B second stroke sensor, 70 brake ECU.

Claims (6)

A first stroke sensor for detecting a first detection value corresponding to an operation amount of the brake pedal;
A second stroke sensor for detecting a second detection value corresponding to the amount of operation of the brake pedal;
Zero point correction means for performing zero point correction on the position of the brake pedal when not operated, using the first detection value or the second detection value;
An abnormality determining means for determining whether an abnormality has occurred in the first stroke sensor or the second stroke sensor;
Storage means for holding a first deviation characteristic indicating a correspondence between the first detection value and the deviation, and a second deviation characteristic indicating a correspondence between the second detection value and the deviation;
With
The abnormality determination means uses the first detection value, the first deviation characteristic, and the second deviation characteristic that are detected immediately after the zero point correction is performed, and the second detection that is detected immediately after the zero point correction is performed. It is determined whether or not the value is out of a variation range within which the value is within the range, and it is determined that an abnormality has occurred in the first stroke sensor or the second stroke sensor when the second detection value is out of the variation range. Sensor abnormality determination device. The abnormality determining means includes
With reference to the first deviation characteristic, the operation amount range of the brake pedal is estimated based on the first detection value detected immediately after execution of the zero point correction and the deviation,
Referring to the second deviation characteristic, estimating a variation range within which the second detection value should be based on the estimated operation range of the brake pedal,
It is determined whether or not the second detection value immediately after execution of the zero point correction is within the estimated variation range, and when the second detection value is outside the estimated variation range, the first stroke sensor or the The sensor abnormality determination device according to claim 1, wherein it is determined that an abnormality has occurred in the second stroke sensor.   The zero point correction means is configured to detect the first position when one of the first position of the brake pedal calculated based on the first detection value and the second position of the brake pedal calculated based on the second detection value satisfies the correction condition. 3. The sensor abnormality determination device according to claim 1, wherein zero point correction is executed for both the second position and the second position.   The sensor abnormality determination device according to any one of claims 1 to 3, wherein the first stroke sensor or the second stroke sensor is a non-contact sensor.   The sensor abnormality determination device according to any one of claims 1 to 4, wherein the first stroke sensor and the second stroke sensor have a gain set to match different brake pedal structures. A sensor that determines whether an abnormality has occurred in the first stroke sensor that detects the first detection value corresponding to the operation amount of the brake pedal or the second stroke sensor that detects the second detection value corresponding to the operation amount of the brake pedal In the abnormality judgment method,
Performing zero point correction on the position of the brake pedal when it is not operated using the first detection value or the second detection value;
The first detection value detected immediately after the zero point correction is executed, the first deviation characteristic indicating the correspondence between the first detection value and the deviation, and the second deviation characteristic indicating the correspondence between the second detection value and the deviation. A step of determining whether or not the second detection value detected immediately after the execution of the zero point correction is outside a variation range to be accommodated;
Determining that an abnormality has occurred in the first stroke sensor or the second stroke sensor when the second detection value is outside a variation range;
A sensor abnormality determination method comprising:

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