JP5221983B2 - Fault diagnosis system - Google Patents

Description

The present invention relates to fault diagnosis system.

In recent years, the need for monitoring the negative pressure of a brake booster using negative engine pressure has increased as the efficiency of engines mounted on automobiles and the like has increased and the number of hybrid vehicles has increased. For this reason, the importance of detecting a failure of the negative pressure sensor inevitably provided in the brake booster is also increasing.
By the way, in order to detect such a failure of the negative pressure sensor, it is necessary to detect that the depression operation of the brake pedal is being performed in the previous stage.
Conventionally, in order to detect the operation state of the brake pedal, a brake switch that is turned on by depressing the brake pedal is known. However, since the brake switch is a mechanical part, it has a disadvantage that the detection signal is not reliable. It has.

Therefore, conventionally, failure diagnosis of the negative pressure sensor is performed from the negative pressure output value of the brake booster by limiting the conditions under which the negative pressure of the brake booster fluctuates from factors other than the signal from the brake switch. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 11-36927

However, the conditions under which the negative pressure of the brake booster fluctuates depend on, for example, the engine speed, the deceleration calculated from the vehicle speed, the operation state of the accelerator pedal, the shift position, etc. It was necessary to limit.
For this reason, for example, under specific conditions such as a low vehicle speed range and an ascending / descending slope, there is a problem that diagnosis cannot be performed even when a failure diagnosis of the negative pressure sensor is required.

  On the other hand, the output signal of the brake switch clearly indicates the driver's intention to operate the brake, and it is better to perform failure diagnosis of the negative pressure sensor on the assumption that such a brake switch is used. Diagnosis is not limited to specific conditions. For this reason, development of the technique which concerns on the failure diagnosis which can improve the reliability of a brake switch is desired.

The present invention has been made in view of such circumstances, and an object thereof is to provide a diagnostic system failure because Ru can increase the reliability of the brake switch.

In order to achieve the above object, a failure diagnosis system of the present invention comprises a first and second switch for detecting on / off of a brake operation, and a failure diagnosis device for diagnosing the presence or absence of a failure in the first and second switches. In the failure diagnosis system used, the first switch is a brake switch for lighting a brake lamp, the second switch is for other elements of the vehicle, and the first switch and the first switch Based on the output relationship with the two switches, the failure of the first and second switches is diagnosed, and the failure diagnosis apparatus has a fluctuation in the output of either the first or second switch. The output immediately before the output fluctuates is the same at the first and second switches, and the output after a predetermined time is the same at the first and second switches, and immediately before Said output and place Said output and said first time after, when a mismatch together with the second switch, the first being adapted to the second switch is diagnosed to be normal, the first by the failure diagnosis device When the second switch is diagnosed as being normal, a failure diagnosis of the negative pressure sensor is performed by a negative pressure sensor provided in association with the brake booster.

According to this failure diagnosis system, the first and second switches are provided independently to detect on / off of the brake operation, and the first and second switches are based on the output relationship between the two first and second switches. Therefore, it is possible to ensure the accuracy of the failure diagnosis, and it is possible to make a diagnosis without being limited to the specific conditions as described above.
In addition, a change in the output of one switch and a change in the output of the other switch are mutually diagnosed every predetermined time, and it is diagnosed that the first and second switches are normal from the state of the output every predetermined time. Therefore, failure diagnosis of the first and second switches can be performed with higher reliability.
And according to this failure diagnosis system, failure diagnosis of the negative pressure sensor can be performed on the premise that the brake switch is used, and although it is a simple configuration, it is limited to the specific conditions as described above. Therefore, it is possible to diagnose a negative pressure sensor with high reliability.

In the failure diagnosis system for a failure diagnosis system according to the present invention, the second switch is for an idle stop control device for stopping driving of the engine, and the idle stop control device is based on an output of the second switch. It is preferable that the engine is controlled to stop at least.

According to this failure diagnosis system , it becomes possible to perform failure diagnosis of the first and second switches by using a switch for an idle stop control device that stops driving of the engine, and a separate switch is provided. The failure diagnosis of the brake switch can be suitably performed using the existing switch.

According to the present invention, the fault diagnosis system using a therefore is Ru can disabilities diagnostic apparatus to improve the reliability of the brake switch is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate.
FIG. 1 is a block diagram for explaining functions of a failure diagnosis system using a failure diagnosis apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a configuration around a brake booster. In the following, a failure diagnosis device applied to an automobile will be described, but this is not intended to limit the vehicle provided with the failure diagnosis device.

As shown in FIG. 1, a failure diagnosis apparatus 10 according to the present embodiment includes a switch unit 10A and a control unit 10B. The switch unit 10A includes an independent first switch 1 that detects on / off of a brake operation, and A second switch 2 is provided. Such a failure diagnosis apparatus 10 can diagnose whether or not the first switch 1 and the second switch 2 are functioning normally as will be described later.
Both the first switch 1 and the second switch 2 are on / off switches having mechanical contacts (not shown). In the present embodiment, the first switch 1 is a brake switch for lighting a brake lamp (not shown). The second switch 2 is a switch for an idle stop control device that stops driving of an engine (not shown).

  As shown in FIG. 2, the first switch 1 and the second switch 2 are juxtaposed to the side of the brake pedal P, and are turned on in synchronization with the depression of the brake pedal P. It is turned off with the release of. In this example, since the brake pedal P is rotated about the support shaft P1, the first and second switches 1 and 2 are located on the side away from the support shaft P1 during the stepping operation. The first switch 1 is turned on first, and then the second switch 2 is turned on. The signals from the first switch 1 and the second switch 2 are input to the ECU 20 through signal lines, and are used as triggers for turning on the brake lamps and for idling stop control. This is used as a trigger for diagnosing the failure of the switches 1 and 2.

The control unit 10B includes a storage unit 11, a delay timer 12, a determination unit 13, and a diagnosis unit 14. The storage unit 11 can sequentially store the ON signal or OFF signal from the first switch 1 and the second switch 2 as data in time series, and can retrieve the previously stored data in the stored order. It is configured to be possible. As the storage unit 11, for example, a FIFO memory or a random access memory can be used.
The delay timer 12 starts counting down for a preset time when the output of either the first switch 1 or the second switch 2 fluctuates, that is, when an on signal or an off signal is input.

  The determination unit 13 determines whether the on signal or the off signal output from the first and second switches 1 and 2 match. Specifically, when the output of any of the first and second switches 1 and 2 fluctuates, the determination unit 13 determines that the output immediately before the output fluctuates is the same at the first and second switches 1 and 2. It is determined whether or not the output after counting (after a predetermined time) of the delay timer 12 is coincident between the first and second switches 1 and 2, and the immediately preceding said It is determined whether or not the output and the output after counting are inconsistent in the first and second switches 1 and 2. The output immediately before the output fluctuation is input from the storage unit 11 to the determination unit 13 (see FIG. 1).

The diagnosis unit 14 diagnoses whether or not the first and second switches 1 and 2 are normal based on the determination of the determination unit 13. Here, the diagnosis unit 14 diagnoses that the first and second switches 1 and 2 are normal when the determination unit 13 determines as follows. Specifically, when the output of any one of the first and second switches 1 and 2 fluctuates, the determination unit 13 determines that the output immediately before the output fluctuates is the same at the first and second switches 1 and 2. It is determined that the output after counting of the delay timer 12 is the same at the first and second switches 1 and 2, and the output immediately before and the output after counting are When it is determined that the first and second switches 1 and 2 are inconsistent, the diagnosis unit 14 diagnoses that the first and second switches 1 and 2 are normal. Therefore, when any of these determinations is different from the above state, it is diagnosed that at least one of the first and second switches 1 and 2 is abnormal.
The diagnosis result by the diagnosis unit 14 is output to the negative pressure sensor failure diagnosis device 30.

The negative pressure sensor failure diagnosis device 30 performs failure diagnosis of the negative pressure sensor 6 based on the diagnosis result from the diagnosis unit 14. Specifically, the negative pressure sensor failure diagnosis device 30 detects the failure of the negative pressure sensor 6 only when the diagnosis unit 14 inputs a diagnosis result that the first and second switches 1 and 2 are both normal. When diagnosis is performed and a diagnosis result indicating that the first and second switches 1 and 2 are abnormal is input, failure diagnosis of the negative pressure sensor 6 is not performed.
In the failure diagnosis of the negative pressure sensor 6 by the negative pressure sensor failure diagnosis device 30, for example, a deviation exceeding an allowable value occurs between an intake negative pressure of an engine (not shown) and a measured value measured by the negative pressure sensor 6. This can be done by determining that the negative pressure sensor 6 is out of order.

As shown in FIG. 2, as described above, the first and second switches 1 and 2 are juxtaposed to the side of the brake pedal P, and as the brake pedal P is depressed or released. It is turned on and off in synchronism, and the signal is output to the ECU 20.
The brake pedal P is connected to the brake booster 3, and the brake booster 3 is connected to the intake manifold 5 via the negative pressure pipe 4. A negative pressure sensor 6 is connected to the negative pressure pipe 4, and the internal pressure of the brake booster 3 can be detected by the negative pressure sensor 6. The detection value of the negative pressure sensor 6 is output to the ECU 20 and used for output control of the engine and the like, and also used for failure diagnosis of the negative pressure sensor failure diagnosis device 30 as described above.
The negative pressure pipe 4 is provided with a check valve 4a, and the flow from the intake manifold 5 side to the brake booster 3 is prevented.

Next, the procedure for performing failure diagnosis of the first and second switches 1 and 2 will be described in detail with reference to FIGS. 1 and 2 as appropriate with reference to the flowchart of FIG.
First, when the brake pedal P is depressed, either the first switch 1 or the second switch 2 is turned on (Yes in step S1), and the signal is input to the ECU 20. Then, the delay timer 12 starts counting down by the ECU 20 (step S2).

When the count of the delay timer 12 becomes zero (0) (Yes in Step S3, and when No in Step S3, Step S3 is repeated until the count becomes zero), the determination unit 13 first changes the output. It is determined whether or not the output immediately before is matched between the first and second switches 1 and 2 (step S4). If it is determined that they match (Yes in step S4), the process proceeds to step S5. Then, it is determined whether or not the output after the count of the delay timer 12 coincides with the first and second switches 1 and 2.
Then, when the determination unit 13 determines in step S5 that the output after the count of the delay timer 12 is the same in the first and second switches 1 and 2 (Yes in step S5), the determination unit 13 proceeds to step S6. It is determined whether or not the immediately preceding output and the counted output are inconsistent in the first and second switches 1 and 2.
Then, when the determination unit 13 determines in step S6 that the output immediately before and the output after counting are inconsistent in the first and second switches 1 and 2 (Yes in step S6), the determination unit 13 proceeds to step S7. The diagnosis unit 14 diagnoses that the first and second switches 1 and 2 are normal. That is, it is diagnosed that the first and second switches 1 and 2 are normal only when it is determined to be Yes in steps S4 to S6.

On the other hand, if it is determined in step S4 that the output immediately before the output fluctuates does not match between the first and second switches 1 and 2 (No in step S4), the process proceeds to step S8 and diagnosis is performed. The unit 14 diagnoses that the first and second switches 1 and 2 are abnormal.
Further, when it is determined in step S5 that the output after the count of the delay timer 12 does not match between the first and second switches 1 and 2 (No in step S5), or the previous output in step S6. Similarly, when it is determined that the output after counting is not inconsistent in the first and second switches 1 and 2 (matching, No in step S6), the process proceeds to step S8, and the diagnosis unit 14 The first and second switches 1 and 2 are diagnosed as abnormal.
That is, in Steps S4 to S6, when it is determined that even one is No, it is diagnosed that the first and second switches 1 and 2 are abnormal.

  Next, failure determination of the first and second switches 1 and 2 will be described with reference to the time chart of FIG. In the following description, a case where the first switch 1 is turned on first and then the second switch 2 is turned on by the depression operation of the brake pedal P will be described as an example, but the turn-on order is not limited.

  When the brake pedal P is depressed at time t1, the first switch 1 is turned on first as shown in FIG. 4A, and the delay timer 12 counts down as shown in FIG. 4C. Start. At the same time, the determination unit 13 reads the output immediately before the output fluctuates from the storage unit 11, and determines whether these outputs match between the first and second switches 1 and 2. In this case, as shown in FIGS. 4A and 4B, immediately before the time t1, both the first and second switches 1 and 2 are in the off state. , 2 match.

  As shown in FIG. 4B, at time t2, the second switch 2 is turned on, and the signal is input to the ECU 20.

At time t3, as shown in FIG. 4C, when the delay timer 12 finishes counting, the determination unit 13 determines whether the outputs of the first and second switches 1 and 2 match, In addition, it is determined whether or not the immediately preceding output and the counted output are inconsistent in the first and second switches 1 and 2. In this case, as shown in FIGS. 4A and 4B, the outputs of the first and second switches 1 and 2 at the time t3 coincide with each other in the ON state, and the output immediately before and the count after the count The output is determined to be inconsistent between the off state and the on state in the first and second switches 1 and 2.
Therefore, based on the above determination, as shown in FIG. 4D, the diagnosis unit 14 diagnoses that the first and second switches 1 and 2 are normal.

  Similarly, when the depression of the brake pedal P is released at time t4, the second switch 2 is turned off first as shown in FIG. 4 (b), and the delay as shown in FIG. 4 (c). Timer 12 starts counting down. At the same time, the determination unit 13 reads the output immediately before the output fluctuates from the storage unit 11, and determines whether these outputs match between the first and second switches 1 and 2. In this case, as shown in FIGS. 4A and 4B, immediately before time t4, the first and second switches 1 and 2 are both in the on state. , 2 match.

  As shown in FIG. 4A, at time t5, the first switch 1 is turned off and the signal is input to the ECU 20.

At time t6, as shown in FIG. 4C, when the delay timer 12 finishes counting, the determination unit 13 determines whether or not the outputs of the first and second switches 1 and 2 match, In addition, it is determined whether or not the immediately preceding output and the counted output are inconsistent in the first and second switches 1 and 2. In this case, as shown in FIGS. 4A and 4B, the outputs of the first and second switches 1 and 2 at the time t6 coincide with each other in the OFF state, and the output immediately before and the count after the counting are the same. The output is determined to be inconsistent between the on and off states of the first and second switches 1 and 2.
Therefore, based on the above determination, as shown in FIG. 4D, the diagnosis unit 14 maintains a diagnosis that the first and second switches 1 and 2 are normal. Accordingly, it is permitted to perform the failure diagnosis of the negative pressure sensor 6 by the negative pressure sensor failure diagnosis device 30, and the vehicle based on the measured value of the negative pressure sensor 6 when the negative pressure sensor 6 is diagnosed as normal. Is controlled.

  Here, the determination when one of the first and second switches 1 and 2 fails will be described with reference to FIG. FIG. 5 exemplifies a case where the second switch 2 fails, and assumes a case where the second switch 2 fails after time t13. In the figure, the first determination refers to the determination by the determination unit 13 as to whether or not the output immediately before the output fluctuates is the same at the first and second switches 1 and 2. Similarly, the second determination is a determination of whether or not the output after counting of the delay timer 12 is the same in the first and second switches 1 and 2, and the third determination is Similarly, it is shown whether or not the immediately preceding output and the counted output are inconsistent in the first and second switches 1 and 2.

  As shown in FIGS. 5 (a) and 5 (b), at time t11 to time t13, the first and second switches 1 and 2 are both diagnosed as normal by the diagnosis unit 14 because the on / off states are both synchronized. The

  At time t14, when the second switch 2 fails and the brake pedal P is released, the second switch 2 remains on, but the determination unit 13 determines that the second determination is NG (described above). It is determined that the answer is No in step S5 (see FIG. 3). That is, since the NG determination is included in the first to third determinations, the comprehensive determination is NG. Thereby, as shown in FIG.5 (d), it is diagnosed by the diagnostic part 14 that it is abnormal. In FIG. 5C, for convenience of explanation, the first to third determinations are all performed. However, as in the flowchart of FIG. 3 described above, determination of No (for example, determination of No in step S4) ), The process proceeds to step S8 (without performing the second and third determinations), and the diagnosis unit 14 diagnoses that the first and second switches 1 and 2 are abnormal. In addition, as shown in FIG.5 (c), you may comprise so that these may be determined comprehensively by performing all the determinations of 1st determination-3rd determination.

From time t14 to time t18, as shown in FIG. 5C, since the NG determination is included in the first to third determinations, the comprehensive determination is NG. Thereby, as shown in FIG.5 (d), it is diagnosed by the diagnostic part 14 that it is abnormal. As a result, idle stop control, all cylinder suspension control, and the like are not performed.
Further, after time t14, that is, after the diagnosis unit 14 diagnoses that there is an abnormality, the failure determination permission flag of the negative pressure sensor 6 by the negative pressure sensor failure diagnosis device 30 is as shown in FIG. It becomes “0” (not permitted), and the failure determination of the negative pressure sensor 6 is not performed. Thereby, after time t14, control using the measured value of the negative pressure sensor 6 is not performed.

  According to the failure diagnosis apparatus 10 of the present embodiment described above, the first and second switches 1 and 2 that detect the on / off of the brake operation are provided, and the two first and second switches 1 and 2 are provided. The failure diagnosis of the first and second switches 1 and 2 is diagnosed on the basis of the output relationship by the above, so that it is possible to ensure the accuracy of failure diagnosis and diagnosis that is not limited to a specific condition as in the past. It is. In other words, failure diagnosis of the first and second switches 1 and 2 can be performed even under conditions other than specific conditions. Even under specific conditions such as the above, when a failure diagnosis of the negative pressure sensor is required, the diagnosis can be performed.

  Further, the failure diagnosis apparatus 10 is configured such that when an output change occurs from any one of the first and second switches 1 and 2, the output immediately before the output change is the first and second switches 1 and 2. The first and second switches 1 and 2 match the output after the count of the delay timer 12 and the first and second switches 1 and 2 match. 2 is inconsistent, the first and second switches 1 and 2 are diagnosed as being normal. Therefore, the output fluctuation of one switch and the output fluctuation of the other switch are mutually diagnosed at predetermined intervals. Thus, it can be diagnosed that the first and second switches 1 and 2 are normal from the state every predetermined time, and the failure diagnosis of the first and second switches 1 and 2 can be performed with higher reliability. .

  Further, since the second switch 2 is for the idle stop control device, it is not necessary to provide a separate switch, and the failure diagnosis of the first and second switches 1 and 2 is preferably performed using the existing switch. be able to.

  In the failure diagnosis system using the failure diagnosis device 10, the negative pressure provided in the brake booster 3 when the failure diagnosis device 10 diagnoses that the first and second switches 1 and 2 are normal. The failure diagnosis of the negative pressure sensor 6 by the sensor 6 can be performed, and the negative pressure sensor 6 can be diagnosed with high reliability without being limited to the specific conditions as in the past while having a simple configuration. is there.

  Further, the second switch 2 may be used for other elements of the vehicle, such as a switch for controlling cruise control.

It is a block diagram for demonstrating the function of the failure diagnosis system using the failure diagnosis apparatus concerning one Embodiment of this invention. It is a schematic diagram which shows the structure around a brake booster. It is a flowchart for demonstrating failure diagnosis. (A)-(d) is a time chart for demonstrating failure diagnosis. (A)-(e) is explanatory drawing for demonstrating failure diagnosis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st switch 2 2nd switch 3 Brake booster 6 Negative pressure sensor 10 Failure diagnosis device 10A Switch part 10B Control part 11 Memory | storage part 12 Delay timer 13 Judgment part 14 Diagnosis part 20 ECU
30 Negative pressure sensor failure diagnosis device P Brake pedal

Claims (2)

A failure diagnosis system that includes first and second switches that detect on / off of a brake operation, and that uses a failure diagnosis device that diagnoses the presence or absence of a failure of the first and second switches,
The first switch is a brake switch for lighting a brake lamp;
The second switch is for other elements of the vehicle;
Based on the output relationship between the first switch and the second switch, the failure of the first and second switches is diagnosed,
The fault diagnosis apparatus is
When there is a change in the output of any of the first and second switches, the output immediately before the change in the output coincides with the first and second switches, and a predetermined time later The first and second switches when the outputs match at the first and second switches, and the output immediately before and the output after a predetermined time do not match at the first and second switches. Is diagnosed as normal ,
When the failure diagnosis device diagnoses that the first and second switches are normal, the failure diagnosis of the negative pressure sensor is performed by the negative pressure sensor provided in association with the brake booster. Fault diagnosis system. The fault diagnosis apparatus is
The second switch is for an idle stop control device that stops driving the engine, and the idle stop control device controls the engine to stop at least based on the output of the second switch. The failure diagnosis system according to claim 1 .

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