JP5927865B2 - Control device having sensor failure diagnosis function - Google Patents

Description

  The present invention relates to a control device having a sensor failure diagnosis function for detecting a failure of a sensor element.

  Conventionally, Patent Document 1 proposes a brake control device that performs failure diagnosis of sensor elements by comparing sensor signals output from a plurality of sensors. Specifically, in the brake control device disclosed in Patent Document 1, if two sensor elements that detect the same physical quantity are normal, the added value of the two sensor signals becomes a predetermined constant value. When a failure occurs, the sensor element failure diagnosis is performed based on the fact that the added value of the two sensor signals does not become the constant value.

JP 2010-167970 A

  However, although the brake control device can perform failure diagnosis of the sensor element, there is no function for diagnosing the failure of the sensor device failure diagnosis function itself by the brake control device. For this reason, there is a problem that the fault diagnosis of the sensor element is mistaken. If braking control is performed based on such a sensor signal, there is a possibility that the braking control cannot be performed properly.

  In a control device having a sensor element failure diagnosis function, a test signal is input to the control device through an external terminal, processed by the control device, and then generated as an output of the control device through another external terminal. It is possible to do so. In this case, if the output of the control device generated through the other external terminal is an output expected in advance, the control device is normal, and if it is not the expected output, it can be diagnosed that the control device has failed. Therefore, an external terminal for inputting the test signal and generating an output from the control device is required, which increases the number of terminals.

  An object of this invention is to provide the control apparatus which can perform own fault diagnosis, without increasing the number of terminals in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, when the addition value or the subtraction value calculated by the calculation unit (1c) is a value outside the predetermined range, one of the two sensor elements fails. In the control device including the first failure detection unit (145, 245) for detecting the failure, the signal change unit (13-22) detects a failure of one of the two sensor elements having the addition value or the subtraction value. The signal transmitted by the two signal lines is changed so as to be the value indicated, and the signal transmitted by the two signal lines is a value indicating that the addition value or the subtraction value indicates failure of the two sensor elements. In a state where the first failure detection unit detects that the two sensor elements are normal, the first failure detection unit (120, 220) detects the first failure. Part is late It is characterized by detecting that it is.

  As described above, when the first failure detection unit detects that the two sensor elements are normal in a state where the addition value or the subtraction value is changed to be a value indicating a failure of the two sensor elements. In addition, it can be diagnosed as a failure of the first failure detection unit. Thereby, in addition to failure diagnosis of the sensor element, it is possible to perform failure diagnosis of the control device itself. The control device itself can be diagnosed without having to have a terminal for inputting a test signal and a terminal for outputting the result. For this reason, it becomes possible to perform own failure diagnosis without increasing the number of terminals.

  In the second aspect of the present invention, two sensor elements are caused to output an inverted signal as a sensor signal for the same physical quantity, and signal change portions are provided on both of two signal lines corresponding to the two sensor elements. Two signals transmitted by two signal lines are changed by superimposing the same test signal on the sensor signals output from the two sensor elements. In such a configuration, the calculation means adds the signal values of the signals transmitted by the two signal lines to calculate the addition value, and the first failure detection unit calculates the addition value calculated by the calculation unit. Is a value outside the predetermined range, it is detected that one of the two sensor elements has failed, and the signal of the signal transmitted by the two signal lines in the sensor value generation means (130, 155) A value correlated with a physical quantity is generated by subtracting the value.

  In this way, the two signals transmitted by the two signal lines are changed by the signal changing unit, and the test signal is superimposed on each of them. In this way, the amplitude of the added value calculated by the calculation unit can be set to be twice the amplitude of the test signal component. For this reason, even if the amplitude of the test signal is reduced, the failure diagnosis of the control device itself can be performed based on the test signal. Therefore, when the amplitude of the test signal is increased, it is difficult to restore the signal output from the sensor element from the signal on which the test signal is superimposed. However, the amplitude of the test signal can be reduced. Thus, the restoration of the sensor signal can be facilitated.

  In the invention according to claim 3, the same signal is output as the sensor signal for the same physical quantity by the two sensor elements, and the signal changing unit is provided in any of the two signal lines corresponding to the two sensor elements, Two signals transmitted by two signal lines are changed by superimposing mutually inverted test signals on sensor signals output from two sensor elements. In such a configuration, the subtracting value calculated by the calculating unit in the first failure detecting unit is calculated by subtracting the signal value of the signal transmitted by the two signal lines by the calculating means. Is a value outside the predetermined range, it is detected that one of the two sensor elements has failed, and the signal of the signal transmitted by the two signal lines is detected by the sensor value generation means (230, 255). A value that correlates to a physical quantity is generated by adding the values.

  In this way, even when two sensor elements output the same signal as the sensor signal with respect to the same physical quantity and the test signals inverted from each other are superimposed on the sensor signals output from the two sensor elements, the claims are also claimed. The same effect as 2 can be obtained.

  The invention according to claim 4 is characterized in that the signal changing section is provided on one of the signal lines corresponding to the two sensor elements.

  Thus, even if the signal changing unit is provided only in one of the signal lines corresponding to the two sensor elements, the failure of the control device itself can be detected. With such a configuration, it is possible to simplify the configuration as compared with the case where both of the signal lines corresponding to the two sensor elements are provided with signal changing units.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a block diagram showing an electrical configuration of a brake ECU according to a first embodiment of the present invention. It is the circuit diagram which showed an example of the connection form of brake ECU1 and various sensors 2-6. It is a flowchart of the braking control including the failure diagnosis process performed by CPU1c of brake ECU1. It is a timing chart of each output including an ECU failure diagnosis period. It is the graph which showed the range of the added value of each sensor signal and the waveform of the sensor signal outputted from the 1st and 2nd sensor parts 11 and 12 to the detected object. It is the circuit diagram which showed an example of the connection form of brake ECU1 concerning the 2nd Embodiment of this invention, and the various sensors 2-6. It is a flowchart of the braking control including the failure diagnosis process performed by CPU1c of brake ECU1. It is a timing chart of each output including an ECU failure diagnosis period. It is the circuit diagram which showed an example of the connection form of brake ECU1 concerning 3rd Embodiment of this invention, and the various sensors 2-6. 4 is a timing chart when a test signal is superimposed on only one sensor signal of the first and second sensor units 11 and 12; It is the circuit diagram which showed an example of the connection form of brake ECU1 and various sensors 2-6 concerning 4th Embodiment of this invention. 4 is a timing chart when a test signal is superimposed on only one sensor signal of the first and second sensor units 11 and 12; It is the circuit diagram which showed an example of the connection form of brake ECU1 and various sensors 2-6 concerning 5th Embodiment of this invention. It is a timing chart in the case of making a 2nd signal into a GND level during ECU failure diagnosis period. It is the figure which showed the waveform when the test signal demonstrated in other embodiment is superimposed. It is the figure which showed the waveform when the test signal demonstrated in other embodiment is superimposed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. In the present embodiment, a control device having a failure diagnosis function will be described by taking a brake electronic control device (hereinafter referred to as a brake ECU) for controlling braking as an example. In the case of the present embodiment, the control device of the present invention is configured by a part provided in the brake ECU and various sensors.

  FIG. 1 is a block diagram illustrating an electrical configuration of a brake ECU according to the present embodiment. As shown in this figure, the brake ECU 1 is connected to a stroke sensor 2, a pressure sensor 3, a negative pressure sensor 4, a yaw rate sensor 5, an acceleration (G) sensor 6 and the like provided in various parts of a brake system (not shown) via signal lines. The brake control using a braking device (not shown) is executed by inputting a signal transmitted from the signal line and performing various calculations based on the input signal.

  The stroke sensor 2 is used to detect a stroke amount of a brake pedal (not shown) and generates a sensor signal corresponding to the stroke. The pressure sensor 3 is used for detecting a master cylinder pressure or the like, and generates a sensor signal corresponding to the detected pressure. The negative pressure sensor 4 is used for detecting engine negative pressure and the like, and generates a sensor signal corresponding to the detected negative pressure. The yaw rate sensor 5 is used to detect a yaw value generated in the vehicle, and generates a sensor signal corresponding to the detected yaw value. The G sensor 6 is used to detect longitudinal acceleration or lateral acceleration generated in the vehicle, and generates a sensor signal corresponding to the detected acceleration. The sensor signals of these various sensors 2 to 6 are respectively input to the brake ECU 1 and used for braking control such as anti-skid control and skid prevention control.

  FIG. 2 is a circuit diagram illustrating an example of a connection form between the brake ECU 1 and the various sensors 2 to 6. Here, a case where the stroke sensor 2 is connected to the brake ECU 1 will be described as an example of the various sensors 2 to 6, but the same connection form is applied to the other sensors 3 to 6 and the brake ECU 1. it can.

  As shown in FIG. 2, the various sensors 2 to 6 include first and second sensor units 11 and 12. Each of the first and second sensor units 11 and 12 includes a sensor element, and is connected to a signal line corresponding to the sensor element and detected by the sensor element (for example, a stroke in the case of the stroke sensor 2). Sensor signals corresponding to are output from the first and second sensor units 11 and 12, respectively. The first and second sensor units 11 and 12 output sensor signals that are the same signal or inverted signals for the same physical quantity, but in the present embodiment, output inverted signals.

  Each of the sensors 2 to 6 includes a test signal generator 13 and a timer 14, and mixing units 15 and 16. The test signal generator 13 outputs a test signal for detecting a failure of the brake ECU 1 (pseudo failure signal). In the present embodiment, a pulse-like output having a predetermined amplitude is generated as the test signal. The timer 14 is for measuring a period during which a failure diagnosis of the sensor failure diagnosis function of the brake ECU 1 is performed (hereinafter referred to as an ECU failure diagnosis period), and at the ECU failure diagnosis period, a test signal is sent to the test signal generator 13. Is generated. The timer 14 measures a predetermined period as an ECU failure diagnosis period. In the present embodiment, as an example, the timer 14 starts measuring the ECU failure diagnosis period when the ignition switch is switched from OFF to ON. I am doing so. The mixing units 15 and 16 superimpose the test signals output from the test signal generator 13 on the sensor signals output from the first and second sensor units 11 and 12.

  As described above, the various sensors 2 to 6 transmit the two sensor signals output from the first and second sensors 11 and 12 to the brake ECU 1, and generate test signals for the two sensor signals during the failure diagnosis period. A signal on which the test signal output from the device 13 is superimposed is transmitted to the brake ECU 1.

  The brake ECU 1 inputs a sensor signal or a signal in which a test signal is superimposed on the sensor signal to a central processing circuit (hereinafter referred to as CPU) 1c through built-in A / D conversion circuits 1a and 1b, Based on this, failure diagnosis and various braking controls are executed. As the failure diagnosis, diagnosis of failure of the first and second sensor units 11 and 12 (specifically, sensor elements) and failure of the sensor failure diagnosis function of the brake ECU 1 (hereinafter referred to as failure of the brake ECU 1 itself) is performed. Yes.

  When the brake ECU 1 diagnoses various failures based on failure of the first and second sensor units 11 and 12 (specifically, sensor elements) and failure diagnosis results of the brake ECU 1 itself, This is reported, and various faults are displayed through indicators provided in the meter 7. Further, the brake ECU 1 executes braking control such as anti-skid control and skid prevention control by controlling an actuator 8 provided in the braking device, for example, a control valve and a motor for driving the pump, based on the sensor signal.

  In such a configuration, the test signal generator 13, the timer 14, and the mixing units 15 and 16 constitute a signal changing unit that changes the sensor signal transmitted by the two signal lines corresponding to the two sensor elements, and A control device is constituted by the brake ECU 1.

  Next, a failure diagnosis method based on the failure diagnosis function provided in the brake ECU 1 according to the present embodiment will be described.

  The brake ECU 1 according to the present embodiment detects a failure of the sensors 2 to 6, specifically, a failure of any of the first and second sensor units 11 and 12 provided in the sensors 2 to 6 as a failure diagnosis function. In addition to the sensor failure diagnosis function, the ECU has a ECU failure diagnosis function for detecting a failure of the brake ECU 1 itself. Various brake controls are executed after performing these fault diagnoses. FIG. 3 shows a flowchart of braking control including a failure diagnosis process executed by the CPU 1c of the brake ECU 1, and FIG. 4 shows a timing chart of each output including an ECU failure diagnosis period. A process executed by the CPU 1c will be described.

  The process shown in FIG. 3 is started, for example, when the ignition switch is switched from OFF to ON, and is executed every predetermined control cycle. In this embodiment, the failure diagnosis of the brake ECU 1 itself is performed with the initial check period after the ignition switch is turned on as the ECU failure diagnosis period, and then the failure diagnosis of the sensors 2 to 6 is performed.

  Specifically, first, in step 100, the first signal is acquired, and in step 105, the second signal is acquired. The first and second signals are signals input to the CPU 1c through the A / D conversion circuits 1a and 1b. In the case of the present embodiment, at the same time that the ignition switch is switched from OFF to ON, the ECU 14 measures the ECU failure diagnosis period, and during that period, each sensor unit 11, 12 outputs from the test signal generator 13. A test signal is superimposed on the sensor signal. In the case of this embodiment, the sensor signals output from the first and second sensors 11 and 12 are inverted signals with respect to the same physical quantity. The test signal has a pulse shape with a predetermined amplitude. Therefore, as shown in FIG. 4, the first and second signals are sensor signals that are inverted signals in which test signals composed of pulse waves having the same phase and amplitude are inverted during the ECU fault diagnosis period. The signal is superimposed. After the ECU failure diagnosis period, the first and second signals become sensor signals that are inverted signals that are inverted from each other.

  In step 110, it is determined whether the internal timer value is less than a predetermined value T1. The internal timer value is a value measured by a timer provided in the CPU 1c, and the predetermined value T1 is a value corresponding to an ECU failure diagnosis period. The CPU 1c measures the ECU failure diagnosis period using an internal timer, and determines whether or not it is during the ECU failure diagnosis period based on whether or not the internal timer value is less than a predetermined value T1.

  If an affirmative determination is made in step 110, the ECU failure diagnosis period is in progress, so the routine proceeds to step 115, where the added value is calculated by adding the first signal and the second signal. As shown in FIG. 4, the addition value is obtained by adding the sensor signals output from the first and second sensor units 11 and 12 that are inverted with each other and the test signal including a pulse wave having the same phase and amplitude. Therefore, the sensor signal component becomes a constant value, and the test signal component appears as a double amplitude. For this reason, the added value has a waveform with a large amplitude around a certain value.

  Then, the process proceeds to step 120, and based on the added value calculated in step 115, it is determined whether or not there is a failure related to the failure diagnosis function of the sensor element of the brake ECU 1, that is, whether or not the brake ECU 1 itself has failed. Specifically, the determination in this step is performed based on whether or not the addition value has reached a sensor failure determination range that indicates a failure of the sensor element. Here, the sensor failure determination range will be described with reference to FIG.

  FIG. 5 shows the waveform of the sensor signal output from the first and second sensor units 11 and 12 and the range of the added value of each sensor signal with respect to the object to be detected (for example, the stroke in the case of the stroke sensor 2). It is a graph.

  As shown in this figure, the sensor signal of the first sensor unit 11 decreases as the value of the detected object increases, and conversely, the sensor signal of the second sensor unit 12 increases as the value of the detected object decreases. Thus, the sensor signals of the first and second sensor units 11 and 12 are inverted signals. For this reason, the addition value of the sensor signals of the first and second sensor units 11 and 12 becomes a constant value and falls within the sensor normality determination range shown in FIG. This sensor normality determination range is a range in which it is assumed that the sensor element has not failed, and a range exceeding the sensor normality determination range is a sensor failure determination range.

  After the ECU failure diagnosis period described later, failure diagnosis of the sensors 2 to 6 is performed, and it is determined whether or not the added value of the first and second signals is within the sensor normality determination range. However, during the ECU failure diagnosis period, the first and second signals are changed so as to have a value indicating a failure of the sensor element, and the added value becomes a value including the test signal component. The sensor failure determination range is reached.

  Therefore, if the failure detection unit of the sensors 2 to 6 of the brake ECU 1 is normal, the added value of the first and second signals reaches the sensor failure determination range during the ECU failure diagnosis period, and within the sensor normal determination range. If there is, the brake ECU 1 is in failure. On the basis of this, in step 120, based on whether the added value of the first and second signals is within the sensor normality determination range or the sensor failure determination range during the ECU failure determination period, the failure related to the sensors 2 to 6 occurs. The result is stored in a memory (not shown) in the CPU 1c.

  And it progresses to step 125 and it is determined using the result of step 120 whether the sensors 2-6 are normal. If the sensors 2 to 6 have failed, the failure detection unit according to the sensors 2 to 6 of the brake ECU 1 does not have the failure targeted by the present embodiment. The sensor value is restored from the two signals, and braking control using a braking device, for example, the actuator 8 is driven based on the restored sensor value to execute anti-skid control, skid prevention control, or the like. If the sensors 2 to 6 are normal, the brake ECU 1 has failed. The process proceeds to step 135 to inform the meter 7 that the brake ECU 1 has failed, and then proceeds to step 140 to control by the braking device. To stop. As a result, it is indicated that the brake ECU 1 has failed using an indicator or the like provided on the meter 7, and the control by the braking device is stopped, so that it is based on the erroneous processing of the failed brake ECU 1. Thus, it is possible to prevent the braking control from being performed.

  On the other hand, if a negative (normal) determination is made at step 110, the process proceeds to step 145 because the ECU failure diagnosis period is exceeded and the normal period is reached. Then, after calculating the added value by adding the first signal and the second signal, it is determined whether there is a failure relating to the sensor elements provided in the first and second sensor units 11 and 12 based on the added value. To do. That is, as described above, it is determined whether the added value is within the sensor normality determination range or the sensor failure determination range, and if it is within the sensor normality determination range, the sensor element has not failed and the sensor failure determination If it is within the range, it is determined that the sensor element has failed, and the result is stored in a memory (not shown) in the CPU 1c.

  Thereafter, the process proceeds to step 150, and it is determined whether or not the sensor element is in failure using the result of step 145. Here, if the sensor element is not in failure, the process proceeds to step 155, and braking control is executed using the braking device based on the sensor signal. As the sensor signal used at this time, there is a first signal, a second signal, or a difference between the first signal and the second signal (for example, first signal-second signal). That is, since the first signal and the second signal are simply sensor signals output from the first and second sensor units 11 and 12 after the ECU failure diagnosis period, they correspond to the values of the detected objects. Value. Further, since the difference between the first signal and the second signal is an inverted signal obtained by inverting each other, it becomes a value corresponding to the value of the object to be detected as shown in FIG. Therefore, the braking control can be executed using the first signal, the second signal, or the difference between the first signal and the second signal as a sensor signal. In this way, braking control including failure diagnosis processing is executed.

  On the other hand, if the sensor is malfunctioning, the process proceeds to step 160 to inform the meter 7 that the sensor is malfunctioning, and then proceeds to step 165 to prohibit the braking device from being controlled by the malfunctioning sensor. As a result, it is indicated that one of the sensors 2 to 6 is malfunctioning using an indicator provided in the meter 7, and control by the braking device by the sensor is prohibited, and an erroneous sensor signal is generated. Based on this, the braking control is prevented from being executed. For example, when a sensor used for the skid prevention control, such as the yaw rate sensor 5, has failed, processing such as prohibiting the skid prevention control is performed.

  As described above, according to the brake ECU 1 according to the present embodiment, in addition to the failure diagnosis of the sensor element, the failure diagnosis function of the brake ECU 1 itself, specifically, the failure diagnosis function that detects the failure of the sensor element. Fault diagnosis can be performed. The brake ECU 1 can perform failure diagnosis of the brake ECU 1 without providing a terminal for inputting a test signal and a terminal for outputting the result of the failure diagnosis of the brake ECU 1 itself. For this reason, it becomes possible to perform own failure diagnosis without increasing the number of terminals.

  In the present embodiment, the first and second signals are changed by superimposing the test signal on both of the sensor signals transmitted by the two signal lines. In this way, the amplitude of the added value of the first signal and the second signal can be made twice the amplitude of the test signal component. For this reason, even if the amplitude of the test signal is reduced, the failure diagnosis of the brake ECU 1 itself can be performed based on the test signal. Therefore, when the amplitude of the test signal is increased, it is difficult to restore the sensor signal from the first and second signals. However, the sensor signal can be restored by reducing the amplitude of the test signal. Can be facilitated.

(Second Embodiment)
A second embodiment of the present invention will be described. This embodiment is different from the first embodiment because the first and second signals input to the brake ECU 1 are changed with respect to the first embodiment, and the other is the same as the first embodiment. Only the part will be described.

  FIG. 6 is a circuit diagram illustrating an example of a connection form between the brake ECU 1 and the various sensors 2 to 6. As shown in this figure, in the present embodiment, the first and second sensor units 11 and 12 provided in the various sensors 2 to 6 output sensor signals of the same signal for the same physical quantity.

  Further, a test signal is output from the test signal generator 13 during the ECU failure diagnosis period based on the measurement of the timer 14, but with respect to one of the sensor signals of the first and second sensor units 11 and 12, Superimposes a test signal and superimposes an inverted test signal on the other. Specifically, the test signal output from the test signal generator 13 is inverted by the NOT circuit 17, then transmitted to the mixing unit 15, and the test signal inverted with respect to the sensor signal output from the first sensor unit 11. Is superimposed on the first signal. Further, the test signal output from the test signal generator 13 is transmitted to the mixing unit 16 through the buffer 18, and a second signal is generated by superimposing the test signal on the sensor signal output from the second sensor unit 12. Yes. Other configurations are basically the same as those in the first embodiment.

  In the present embodiment, the process executed by the CPU 1c of the brake ECU 1 is also different from the first embodiment. FIG. 7 shows a flowchart of a braking control including a failure diagnosis process executed by the CPU 1c of the brake ECU 1, and FIG. 8 shows a timing chart of each output including an ECU failure diagnosis period. A process executed by the CPU 1c will be described.

  The process shown in FIG. 7 is started, for example, when the ignition switch is switched from OFF to ON, and is executed every predetermined control cycle. Also in this embodiment, the failure diagnosis of the brake ECU 1 itself is performed with the initial check period after the ignition switch is turned on as the ECU failure diagnosis period, and then the failure diagnosis of the sensors 2 to 6 is performed.

  Specifically, first, in steps 200 and 205, the first and second signals are acquired in the same manner as in steps 100 and 105 of FIG. Also in the present embodiment, at the same time that the ignition switch is switched from OFF to ON, the ECU 14 measures the ECU failure diagnosis period, and the test signal generator 13 outputs a test signal during the period. For this reason, a signal obtained by superimposing an inverted test signal on the sensor signal output from the first sensor unit 11 becomes the first signal, and a test signal is superimposed on the sensor signal output by the second sensor unit 12. Becomes the second signal. That is, in the present embodiment, the sensor signals output from the first and second sensors 11 and 12 are the same signal for the same physical quantity. The test signal has a pulse shape with a predetermined amplitude. For this reason, as shown in FIG. 8, the first and second signals are signals in which a pulse wave having an opposite phase during the ECU fault diagnosis period is superimposed on the same sensor signal. Then, after the ECU failure diagnosis period, the first and second signals are the same signal.

  Subsequently, in step 210, it is determined whether or not the internal timer value is less than the predetermined value T1 as in step 110 of FIG. 3, and if an affirmative determination is made, the process proceeds to step 215 to subtract the first and second signals. To calculate the subtraction value. This subtraction value is a value obtained by subtracting the same sensor signal output from the first and second sensor units 11 and 12 and adding a pulse wave having an opposite phase amplitude. Becomes a constant value (zero), and the test signal component appears as double amplitude. For this reason, the subtraction value has a waveform with a large amplitude centering on a certain value.

  Then, the process proceeds to step 220, and based on the subtraction value calculated in step 215, the presence / absence of a failure relating to the failure diagnosis function of the sensor elements provided in the first and second sensor units 11 and 12 of the brake ECU 1 is determined. Since the subtraction value calculated in step 215 has a waveform with a large amplitude centering on a constant value, similarly to the addition value calculated in step 115 of FIG. 3, the subtraction value is assumed to be a failure of the sensor element. The determination in this step can be performed based on whether the sensor failure determination range is reached or the sensor normality determination range is reached.

  Thereafter, in steps 225 to 240, the same processing as in steps 125 to 140 in FIG. 3 is performed to determine whether or not the brake ECU 1 itself has failed, and the failure targeted by this embodiment has occurred. If not, braking control is executed. If a failure occurs, a warning is given and control by the braking device is stopped.

  On the other hand, if a negative (normal) determination is made in step 210, the process proceeds to step 245 because the ECU failure diagnosis period is exceeded and the normal period is reached. Then, after calculating the subtraction value by subtracting the first signal and the second signal, the presence / absence of a failure relating to the sensor element provided in the first and second sensor units 11 and 12 is determined based on the subtraction value. To do. That is, it is determined whether the subtraction value is within the sensor normality determination range or the sensor failure determination range. If the subtraction value is within the sensor normality determination range, the sensor element has not failed and is within the sensor failure determination range. It is determined that the sensor element has failed, and the result is stored in a memory (not shown) in the CPU 1c.

  Thereafter, in steps 250 to 265, the same processing as in steps 150 to 165 in FIG. 3 is performed to determine whether or not the sensor element has failed. If not, the braking control is executed. If so, a warning is given and control by the braking device is prohibited. In this way, braking control including failure diagnosis processing is executed.

  As described above, the first and second sensor units 11 and 12 output sensor signals that are the same signal with respect to the same physical quantity, and pulse waves that are amplified in opposite phases during the ECU fault diagnosis period are the same signal. Even if the first and second signals superimposed on the sensor signal are used, the same effect as in the first embodiment can be obtained.

(Third embodiment)
A third embodiment of the present invention will be described. This embodiment is also different from the first embodiment because the first and second signals input to the brake ECU 1 are changed with respect to the first embodiment, and the other aspects are the same as the first embodiment. Only the part will be described.

  FIG. 9 is a circuit diagram illustrating an example of a connection form between the brake ECU 1 and the various sensors 2 to 6. As shown in this figure, in this embodiment, the first and second sensor units 11 and 12 provided in the various sensors 2 to 6 output sensor signals that are inverted signals with respect to the same physical quantity. However, the test signal output from the test signal generator 13 is superimposed only on the sensor signal of the second sensor unit 12.

  As described above, even when the test signal is superimposed on only one of the first and second sensor units 11 and 12, the first implementation is performed by performing various processes of the braking control shown in the flowchart of FIG. Similarly to the embodiment, it is possible to execute braking control including failure diagnosis processing of the brake ECU 1 itself in addition to the failure of the sensor element.

  That is, as in the present embodiment, a timing chart in the case where the test signal is superimposed on only one of the first and second sensor units 11 and 12 is expressed as shown in FIG. The added value of the signal is a value obtained by superimposing a pulse wave having an amplitude corresponding to the test signal around a constant value. For this reason, if the amplitude of the added value is smaller than that of the first embodiment but the amplitude is set to reach the sensor failure determination range, the ECU is similar to the first embodiment. During the failure diagnosis period, it is possible to perform a failure diagnosis of the brake ECU 1 itself by determining whether the added value reaches the sensor failure determination range or the sensor normality determination range.

  As described above, even when the test signal is superimposed on only one of the first and second sensor units 11 and 12, the same effect as that of the first embodiment can be obtained. With such a configuration, it is possible to simplify the configuration as compared with the first and second embodiments in which the signal changing units are provided in both of the signal lines corresponding to the two sensor elements.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. This embodiment is also different from the first embodiment because the first and second signals input to the brake ECU 1 are changed with respect to the first embodiment, and the other aspects are the same as the first embodiment. Only the part will be described.

  FIG. 11 is a circuit diagram showing an example of a connection form between the brake ECU 1 and the various sensors 2 to 6. As shown in this figure, in this embodiment, the first and second sensor units 11 and 12 provided in the various sensors 2 to 6 output sensor signals that are inverted signals with respect to the same physical quantity. However, the sensor signal itself output from the first sensor unit 11 is used as the first signal, the sensor signal output from the second sensor unit 12 is used as the second signal, and a pulse with a predetermined amplitude is used during the ECU fault diagnosis period. The test signal is used. Specifically, one of the sensor signal output from the second sensor unit 12 and the test signal output from the test signal generator 13 becomes the second signal by switching the switch 20 by the timer 19. That is, the ECU 19 measures the ECU failure diagnosis period, and during this period, the test signal is the second signal, and after that period, the sensor signal output by the second sensor unit 12 is the second signal.

  Thus, even when the test signal is to be the second signal during the ECU failure diagnosis period, by performing various processes of the braking control shown in the flowchart of FIG. 3, as in the first embodiment, In addition to the failure of the sensor element, it is possible to execute braking control including failure diagnosis processing of the brake ECU 1 itself.

  That is, as in the present embodiment, a timing chart in the case where the test signal is superimposed on only one of the first and second sensor units 11 and 12 is expressed as shown in FIG. The second signal, that is, a test signal composed of a pulse wave with a predetermined amplitude is superimposed on the signal. For this reason, as long as the amplitude of the added value is set so as to reach the sensor failure determination range, as in the first embodiment, whether the added value has reached the sensor failure determination range during the ECU failure diagnosis period. A failure diagnosis of the brake ECU 1 itself can be performed by determining whether it is within the normal determination range.

  In this way, the test signal is the second signal during the ECU failure diagnosis period, and the sensor signal output from the second sensor unit 12 is the second signal after that period. An effect can be obtained. In addition, with such a configuration, it is possible to simplify the configuration as compared with the first and second embodiments in which both signal lines corresponding to the two sensor elements are provided with signal changing units. .

(Fifth embodiment)
A fifth embodiment of the present invention will be described. This embodiment is also different from the first embodiment because the first and second signals input to the brake ECU 1 are changed with respect to the first embodiment, and the other aspects are the same as the first embodiment. Only the part will be described.

  FIG. 13 is a circuit diagram showing an example of a connection form between the brake ECU 1 and the various sensors 2 to 6. As shown in this figure, also in this embodiment, the first and second sensor units 11 and 12 provided in the various sensors 2 to 6 output sensor signals that are inverted signals with respect to the same physical quantity. However, the sensor signal itself output from the first sensor unit 11 is used as the first signal, and the sensor signal output from the second sensor unit 12 is used as the second signal while switching to the GND level during the ECU failure diagnosis period. I have to. Specifically, by switching the switch 22 by the timer 21, either the sensor signal output from the second sensor unit 12 or the GND level becomes the second signal. That is, the ECU 21 measures the ECU failure diagnosis period, and during this period, the GND level is set as the second signal, and after that period, the sensor signal output from the second sensor unit 12 becomes the second signal.

  Thus, even when the second signal is set to the GND level during the ECU failure diagnosis period, by performing various processes of the braking control shown in the flowchart of FIG. 3, as in the first embodiment, In addition to the failure of the sensor element, it is possible to execute braking control including failure diagnosis processing of the brake ECU 1 itself.

  That is, as in the present embodiment, the timing chart when the second signal is set to the GND level during the ECU failure diagnosis period is represented as shown in FIG. 14, and the added value is the second signal with respect to the first signal, That is, it becomes a value in which the GND level is superimposed. For this reason, if the added value with the GND level superimposed is set so as to reach the sensor failure determination range, the added value is detected during the ECU failure diagnosis period as in the first embodiment. The failure diagnosis of the brake ECU 1 itself can be performed by determining whether it is within the sensor normal determination range.

  As described above, even if the second signal is set to the GND level during the ECU failure diagnosis period, and the sensor signal output from the second sensor unit 12 becomes the second signal after the period, the same as in the first embodiment. An effect can be obtained. In addition, with such a configuration, it is possible to simplify the configuration as compared with the first and second embodiments in which both signal lines corresponding to the two sensor elements are provided with signal changing units. .

(Other embodiments)
In the first embodiment and the like, a pulsed test signal having a predetermined amplitude is superimposed on the sensor signal. For example, as shown in FIG. You may make it superimpose on. In the fifth embodiment, the second signal is lowered to the GND level. However, the second signal may be raised to the power supply voltage Vcc level.

  In the first and second embodiments, the test signals having the same amplitude are superimposed on the sensor signals of the first and second sensor units 11 and 12, but the test signals having different amplitudes are superimposed on those signals. Also good.

  In each of the above-described embodiments, the first and second sensor units 11 and 12 are configured by superimposing a test signal on the sensor signals of the first and second sensor units 11 and 12 or setting the second signal to the GND level. The signal values of the first and second signals transmitted to the brake ECU 1 through signal lines corresponding to the sensor elements are changed. The portion that changes the signal value in this manner corresponds to the signal changing unit of the present invention. In each of the above embodiments, the test signal generator 13, the timers 14, 19, 21, the mixing units 15, 16, the NOT circuit 17, and the switch 20 , 22 etc. constitute a signal changing section. In the first and second embodiments, the test signal is superimposed on both of the sensor signals of the first and second sensor units 11 and 12, and the signal value is changed. As in the fifth embodiment, any signal that changes at least one of the first and second signals may be used.

  Moreover, although each said embodiment demonstrated the structure by which the signal change part was provided in the various sensors 2-6, it may be made separate from the various sensors 2-6, and is provided in brake ECU1. May be. Moreover, not only brake ECU1 but the control apparatus with which other ECU is provided may be sufficient.

  Note that the steps shown in each figure correspond to each unit or means for executing various processes. Specifically, a portion of the brake ECU 1 that executes the processes of steps 145 and 245 corresponds to a first failure detector, and a portion that executes the processes of steps 120 and 220 corresponds to a second failure detector. In other words, the portion of the brake ECU 1 that realizes the sensor failure diagnosis function corresponds to the first failure detection unit, and the portion that realizes the ECU failure diagnosis function corresponds to the second failure detection unit. Further, the part that executes the processing of steps 130, 230, 155, and 255 corresponds to the sensor value generating means.

  Further, in each of the above embodiments, during the initial check, the signal values of the first and second signals are always changed to values within the sensor failure determination range. However, as shown in FIG. It may be changed in a predetermined pattern to a value within the range and a value within the sensor failure determination range. In this case, when the failure detection unit related to the sensors 2 to 6 of the brake ECU 1 does not determine whether there is a failure related to the sensors 2 to 6 according to the predetermined pattern, the failure detection unit related to the sensors 2 to 6 of the brake ECU 1 Is determined to be faulty.

  Further, in the above embodiment, the “same signal” may not be a signal having exactly the same phase as long as the accuracy of the failure determination of the brake ECU 1 permits, and the “inverted signal” is as long as the accuracy of the failure determination of the brake ECU 1 permits. It may not be an antiphase signal.

  DESCRIPTION OF SYMBOLS 1 ... Brake ECU, 1c ... CPU, 2 ... Stroke sensor, 3 ... Pressure sensor, 4 ... Negative pressure sensor, 5 ... Yaw rate sensor, 6 ... G sensor, 7 ... Meter, 8 ... Actuator, 11, 12 ... First, 2nd sensor part, 13 ... Test signal generator, 14, 19, 21 ... Timer, 15, 16 ... Mixing part, 17 ... NOT circuit, 20, 22 ... Switch

Claims (4)

Two sensor elements (11, 12) that output the same signal or an inverted signal as sensor signals for the same physical quantity are connected to each other by a signal line corresponding to the sensor element, and a signal signal transmitted by the signal line A calculation unit (1c) for calculating an addition value or a subtraction value by adding or subtracting a value;
A first failure detection unit (145) that detects that one of the two sensor elements has failed when the addition value or the subtraction value calculated by the calculation unit (1c) is outside a predetermined range. 245),
Said two provided in the sensor element in at least one of the two said signal lines corresponding, so that the added value or the subtracted value is a value that indicates the failure of any of the two sensor elements, the two one of the signal change portion for changing at least one of the signal electrical transmission by a signal line (13 to 22),
In the state where the signal changing unit changes the signal transmitted by the two signal lines so that the added value or the subtracted value becomes a value indicating a failure of the two sensor elements. A second failure detection unit (120, 220) for detecting that the first failure detection unit has failed when it is detected that the two sensor elements are normal by failure detection; A control device characterized by that. The two sensor elements output an inverted signal as a sensor signal for the same physical quantity,
The signal changing unit is provided on any of the two signal lines corresponding to the two sensor elements, and superimposes the same test signal on the sensor signals output from the two sensor elements, Change the two signals sent by the signal line,
The computing means computes an added value by adding signal values of signals transmitted by the two signal lines,
The first failure detection unit detects that one of the two sensor elements has failed when the addition value calculated by the calculation unit is a value outside a predetermined range;
The sensor value generation means (130, 155) for subtracting signal values of signals transmitted by the two signal lines to generate a value correlated with the physical quantity is provided. Control device. The two sensor elements output the same signal as a sensor signal for the same physical quantity,
The signal changing unit is provided in any of the two signal lines corresponding to the two sensor elements, and superimposes the inverted test signals on the sensor signals output from the two sensor elements, and Changing two signals transmitted by one signal line,
The calculation means subtracts a signal value of a signal transmitted by the two signal lines to calculate a subtraction value,
The first failure detection unit detects that one of the two sensor elements has failed when the subtraction value calculated by the calculation unit is a value outside a predetermined range;
The sensor value generation means (230, 255) for adding a signal value of a signal transmitted by the two signal lines to generate a value correlated with the physical quantity is provided. Control device.   The control device according to claim 1, wherein the signal changing unit is provided on one of signal lines corresponding to two sensor elements.

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