JP2023006075A - Sensor failure diagnosis device - Google Patents

Abstract

To provide a sensor failure diagnosis device capable of improving reliability of failure diagnosis by accurately calculating engine stop time corresponding to any change in date/time by a driver.SOLUTION: A sensor failure diagnosis device 1 comprises: a clock part 42 for clocking time; an engine state detection part 41 capable of detecting the start and stop of an engine 2; an engine stop time calculation part 31 that acquires time from a clock part 42 on a predetermined periodic basis, assumes the time when the stop of the engine 2 is detected as a base time, and calculates a period of time from the base time to the time acquired by the clock part after the engine 2 stops as an engine stop time; and a failure diagnosis part 32 that performs sensor failure diagnosis if the engine stop time has passed more than a predetermined period of time. If a different time between the time acquired from the clock part and the previously acquired time is out of a predetermined range, the engine stop time calculation part performs correction according to the different time from the base time.SELECTED DRAWING: Figure 2

Description

The present invention relates to a failure diagnosis device for a sensor such as a temperature sensor mounted on a vehicle.

A vehicle equipped with an engine is equipped with an exhaust purification device using, for example, a catalyst, a filter, and a reducing agent such as urea water in order to purify harmful substances such as NOx and PM (Particulate Matter). In this case, the temperature of the exhaust gas must be within a proper range in order to activate the catalyst and the reducing agent. Therefore, an exhaust temperature sensor that detects the temperature of the exhaust gas flowing into the exhaust purification device is provided to monitor the temperature of the exhaust gas.

If there is an abnormality in such an exhaust temperature sensor, appropriate exhaust gas purification control cannot be performed, so the control unit regularly diagnoses the failure of the exhaust temperature sensor. In addition to the exhaust temperature sensor, the vehicle is provided with various temperature sensors, and failure diagnosis of these temperature sensors is also performed. As a method of diagnosing the failure of temperature sensors, for example, based on the temperature difference between the temperature detected by each of the temperature sensors provided in a plurality of engines and the temperature of the outside air (outside air temperature), an abnormality occurs in each temperature sensor. A technique is disclosed in which an abnormality determination means determines whether or not a malfunction is occurring (see Patent Literature 1). Also, by mounting the first temperature sensor and the second temperature sensor on the same circuit board and comparing the output signals (the first signal and the second signal) of both temperature sensors, an abnormality of one of the temperature sensors is detected. A technique has been disclosed (see Patent Document 2).

JP 2007-211714 A JP 2011-140933 A

By the way, the exhaust temperature sensor detects the temperature of a high-temperature environment compared to other temperature sensors, so comparison with temperatures detected by other temperature sensors should be performed after the engine is sufficiently cooled. There is a need. In other words, the time after the engine stops (hereinafter referred to as engine stop time) is measured, and after a predetermined stop time has passed, the failure diagnosis of the exhaust gas temperature sensor is performed.

For example, the engine stop time is calculated by obtaining date and time information from the clock of the meter unit provided on the instrument panel. However, the date and time of the clock of the meter unit can be changed by the driver, and if the date and time of the clock is changed while the engine is stopped, the correct engine stop time cannot be calculated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to calculate an accurate engine stop time in response to a driver's change of date and time in a failure diagnosis device for sensors mounted on a vehicle. To provide a sensor failure diagnosis device capable of improving the reliability of failure diagnosis.

The present invention has been made to solve at least part of the above problems, and can be implemented as the following aspects or application examples.

An abnormality diagnosis device according to this application example is a sensor failure diagnosis device for diagnosing a failure of a sensor mounted on a vehicle, and includes a clock unit that keeps time and an engine capable of detecting start and stop of an engine of the vehicle. The date and time are acquired from the state detection unit and the timekeeping unit at a predetermined cycle, and when the engine state detection unit detects that the engine has stopped, the date and time acquired from the timekeeping unit is used as a base date and time, and the engine is stopped. an engine stop time calculation unit that later calculates the time from the base date and time to the date and time acquired from the time measuring unit as an engine stop time; and the engine stop time calculation unit, when the difference time between the date and time obtained from the timing unit and the date and time obtained last time is outside a predetermined range, the base date and time is characterized in that a correction is performed according to the difference time.

In this way, the sensor diagnosis device periodically acquires date and time information from the clock-like clock of the meter unit, and when the engine stops, sets the base date and time for calculating the engine stop time. , the elapsed date and time from the base date and time is calculated as the engine stop time. If the time difference between the date and time acquired from the timekeeping unit and the time and date acquired last time is outside a predetermined range, the base date and time are corrected according to the time difference. The base date and time can be appropriately corrected even when the date and time information is greatly changed due to the change of the date and time. As a result, it is possible to accurately calculate the engine stop time, and improve the reliability of failure diagnosis of the temperature sensor whose necessity is determined based on the engine stop time.

1 is a schematic configuration diagram of a sensor failure diagnosis device according to an embodiment of the present invention; FIG. 1 is a block diagram showing the configuration of a control system of a sensor failure diagnosis device according to one embodiment of the present invention; FIG. 4 is a flow chart showing a failure diagnosis routine executed by a control unit of the sensor failure diagnosis device according to one embodiment of the present invention; 5 is a time chart showing an example of the operation of the fault diagnosis device according to one embodiment of the present invention in chronological order;

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a fault diagnosis device according to one embodiment of the present invention. A fault diagnosis device 1 of the present embodiment is provided for diagnosing faults in various temperature sensors mounted on a vehicle. As shown in FIG. 1, the fault diagnosis device 1 includes an SCR temperature sensor 21 for measuring the temperature of the exhaust gas flowing into the exhaust purification device 10, which is interposed downstream of the exhaust pipe 3 of the engine 2 of the vehicle, and a cooling device for the engine 2. A refrigerant temperature sensor 22 for detecting the refrigerant temperature on the outlet side of the circuit 4 and an outside air temperature sensor 23 for detecting the outside air temperature are provided. SCR of the SCR temperature sensor 21 is an abbreviation for Selective Catalytic Reduction, and the details will be described later. The fault diagnosis device 1 also includes a control section 30 , an engine state detection section 41 , a timer section 42 , an ignition key 43 , a notification section 44 , and an in-vehicle communication path 5 . Although not particularly limited, in this embodiment, the vehicle is a bus and the engine 2 is a diesel engine.

The engine 2 is provided with a cooling circuit 4 (indicated by a thick dashed line in FIG. 1). The cooling circuit 4 is a flow path for circulating coolant such as cooling water between a water jacket (not shown) provided in the engine 2 and a radiator (not shown). Refrigerant circulates in the cooling circuit 4 by operation of a mechanical pump (not shown) interlocked with the engine 2, and the engine 2 is cooled or warmed up by heat exchange with the refrigerant passing through the water jacket.

An exhaust purification device 10 is provided downstream of the exhaust pipe 3 of the engine 2 . The exhaust pipe 3 is a pipe through which the exhaust from the engine 2 is discharged to the outside. 1 indicates the flow direction of exhaust gas flowing through the exhaust pipe 3. As shown in FIG.

The exhaust purification device 10 includes a front stage portion 11 including a front oxidation catalyst and a diesel particulate filter (also referred to as DPF), and a rear portion including a selective reduction catalyst (hereinafter referred to as "SCR") and a rear oxidation catalyst. , and are provided in order from the upstream side to the downstream side of the exhaust pipe 3 . The pre-stage oxidation catalyst is an oxidation catalyst for reducing carbon monoxide, hydrocarbons, and the like in exhaust gas. A DPF is provided to collect particulate matter (PM) in the exhaust. SCRs are provided to reduce nitrogen oxides (NOx) in the exhaust. Also, the post-stage oxidation catalyst is an oxidation catalyst for reducing urea that has flowed out from the SCR. Although not shown, a urea injection section capable of injecting urea water, which is a reducing agent, into exhaust gas is provided between the front stage section 11 and the rear stage section 12 .

The SCR temperature sensor 21 has a function of detecting the temperature of the exhaust gas flowing into the rear stage portion 12 as the SCR temperature Tscr. The refrigerant temperature sensor 22 has a function of detecting the refrigerant temperature on the outlet side of the cooling circuit 4 as the refrigerant temperature Tw. The outside air temperature sensor 23 has a function of detecting the temperature around the vehicle as an outside air temperature Ta.

The in-vehicle communication path 5 is a communication path including a communication network such as a so-called CAN (Controller Area Network) or a direct connection using a harness or the like, and mediates transmission of information from each component and various sensors mounted on the vehicle.

The control unit 30 is a control unit including an electronic arithmetic unit, a storage unit, and the like, and can communicate with each component and various sensors of the failure diagnosis device 1 via the in-vehicle communication path 5 . The control unit 30 has a function of calculating the engine stop time mainly according to a predetermined program installed in advance, and executing a failure diagnosis of the SCR temperature sensor 21 when the engine is started after the predetermined stop time or more has elapsed. The control unit 30 of the present embodiment is, for example, a dosing control unit (DCU) that is a control unit for monitoring and controlling the exhaust emission control device 10 . Note that the control section 30 may be composed of a plurality of control units, in which case each control unit may cooperate to execute the above functions.

The engine state detector 41 can detect the operating state of the engine including at least starting and stopping of the engine 2 . Specifically, the engine state detector 41 detects the operating state of the engine 2 based on information from other devices, sensors, control units, and the like. For example, the operating state of the engine 2 is detected based on the operating state of the ignition key 43 and the engine speed detected by an engine speed sensor (not shown). When the ignition key 43 is operated to start the engine and the engine speed reaches or exceeds a predetermined speed (for example, idling speed), the start of the engine 2 is detected. Further, when the ignition key 43 is turned off and the engine speed becomes equal to or lower than a predetermined speed (for example, 10 rpm), it is detected that the engine 2 is stopped. Further, the engine state detection unit 41 can detect the operation state of the engine 2 from start to stop as being in operation.

The clock unit 42 is a clock configured as a part of a meter unit provided on, for example, the instrument panel of the driver's seat, and has a function of keeping the date and time. The date and time includes at least year, month, day, and hour, minute, and second to indicate the date. As for the clock function, a known configuration may be used, and a description thereof will be omitted.

The ignition key 43 has an engine start operation for starting the engine 2, an off operation for stopping the engine 2, an on operation for maintaining the operation of the engine 2 after starting the engine 2, and an engine 2 operation. In order to supply power to the electrical components of the vehicle while stopping the power supply, it is possible to perform operations such as turning on the accessory (ACC). In this embodiment, to simplify the explanation, the ACC ON operation and the engine start operation shall be included in the ON operation. Further, the ignition key 43 is not necessarily operated by turning the key, but may be operated by pressing the button.

The notification unit 44 is, for example, an indicator or the like that is provided on the instrument panel of the driver's seat and notifies a warning about a failure.

FIG. 2 is a control block diagram of the fault diagnosis device according to one embodiment of the present invention. The configuration and functions of the control system of the failure diagnosis device 1 will be described below with reference to this figure.

The control unit 30 can communicate with the SCR temperature sensor 21, the refrigerant temperature sensor 22, the outside air temperature sensor 23, the engine state detection unit 41, the timer unit 42, the ignition key 43, and the notification unit 44 via the in-vehicle communication path 5. It is connected. The control unit 30 also includes an engine stop time calculation unit 31 , a failure diagnosis unit 32 , an alarm generation unit 33 and a storage unit 34 .

The engine stop time calculation unit 31 acquires information on the date and time kept by the clock unit 42 (hereinafter referred to as meter date and time tm) via the in-vehicle communication path 5 at a predetermined cycle Cy (for example, one second cycle). The acquisition of the meter date and time tm in this cycle Cy is performed while the control unit 30 is activated, that is, when the ignition key 43 to which power is supplied to the control unit 30 is in the ON operation. On the other hand, while the ignition key 43 is turned off and power is not supplied to the control unit 30, the meter date and time tm is not acquired at the cycle Cy. It should be noted that the predetermined period Cy is set to a time equal to or less than the minimum unit of date and time that can be changed by the timer 42 . For example, when the date and time of the clock unit 42 can be changed in units of minutes, the predetermined period Cy is set to a period of 1 minute or less, and when it can be changed in units of seconds, the predetermined period Cy is set to a period of 1 second or less. be.

The engine stop time calculation unit 31 also sets the meter date tm acquired from the clock unit 42 when the engine state detection unit 41 detects that the engine 2 has stopped as the base date tbase, and stores the base date tbase in the storage unit 34 . The base date and time tbase is reset (for example, updated to the current meter date and time) after it is determined whether or not failure diagnosis is necessary while the ignition key 43 is on. The engine stop time calculator 31 has a function of calculating the time from the base date tbase to the meter date _tmn obtained from the timer 42 after the engine 2 is stopped as the engine stop time tes.

Further, the engine stop time calculation unit 31 determines that the difference time Δt between the meter date tm n acquired in the current cycle and the meter date tm _{n −1} acquired in the previous cycle from the timing unit 42 is outside the predetermined time range. In this case, it has a function of correcting the base date and time tbase according to the difference time Δt. If the amount of change in the clocking unit 42 and the cycle Cy in which the engine stop time calculating unit 31 acquires the date and time match, the difference time Δt=Cy, but the date and time of the timing unit 42 is changed by the driver or the like. Then, the difference time Δt and the cycle Cy diverge. In other words, the predetermined time range is a threshold value for determining whether or not the date and time of the clock unit 42 has been changed, and is different from the period Cy (for example, 1 second) for acquiring date and time information from the clock unit 42. For example, from -tc to tc (a value that is sufficiently small compared to the threshold value for the engine stop time and does not affect the reliability of failure diagnosis, for example, several minutes to several tens of minutes) Range.

The failure diagnosis unit 32 performs failure diagnosis of the SCR temperature sensor 21 when the engine stop time tes has passed a predetermined stop time ta (a time during which the engine can be sufficiently cooled, for example, several hours).

The failure diagnosis unit 32 detects when the temperature difference between the outside air temperature Ta detected by the outside air temperature sensor 23 and the refrigerant temperature Tw detected by the refrigerant temperature sensor 22 is within a predetermined temperature range. When the temperature is sufficiently cooled to almost the same temperature, the difference temperature between the outside air temperature Ta detected by the outside air temperature sensor 23 and the SCR temperature Tscr detected by the SCR temperature sensor 21 is within a predetermined temperature range. Failure diagnosis of the SCR temperature sensor 21 is performed depending on whether or not there is. If the differential temperature is within the predetermined temperature range, the SCR temperature sensor 21 is diagnosed as normal, and if the differential temperature is outside the predetermined range, the SCR temperature sensor 21 is diagnosed as faulty. The predetermined temperature range used for failure diagnosis may be different for each sensor to be diagnosed, or may be the same.

When the failure diagnosis unit 32 diagnoses that the SCR temperature sensor 21 has a failure, the alarm generation unit 33 generates alarm information, outputs the information to the notification unit 44, and the notification unit 44 warns the driver.

The storage unit 34 has a function of storing time information such as the base date and time tbase and the meter date and time tm set by the engine stop time calculation unit 31, failure diagnosis result information obtained by the failure diagnosis unit 32, and the like.

FIG. 3 is a flow chart showing a fault diagnosis routine executed by the controller 30 of the fault diagnosis device according to one embodiment of the present invention. The procedure for fault diagnosis will be described below with reference to the flow chart of FIG. The routine proceeds when the control unit 30 is operable, that is, when at least the ignition key 43 is turned on.

As shown in FIG. 3, as step S101, the engine stop time calculation unit 31 of the control unit 30 determines whether or not the engine state detection unit 41 has detected that the engine 2 has stopped. If the determination result is false (No), that is, if the engine 2 is running, the routine is returned. On the other hand, if the determination result is true (Yes), that is, if the stopped state of the engine 2 is detected, the process proceeds to the next step S102.

In step S<b>102 , the engine stop time calculation section 31 sets the meter date and time _tmn acquired from the clock section 42 at this time as the base date and time tbase and stores it in the storage section 34 . Note that even when the ignition key 43 is turned off and the engine 2 is stopped, electric power is still supplied to the control unit 30 for a period during which the process of step S102 can be executed.

In step S103, the engine stop time calculation unit 31 calculates a predetermined time from the timer unit 42 while power is being supplied to the control unit 30 with the ignition key 43 turned on after the engine is stopped (for example, when the ACC is turned on). The meter date and time _tmn is acquired at the cycle Cy of , and the process proceeds to the next step S104.

In step S104, the engine stop time calculation unit 31 calculates the difference time Δt between the current meter date tm _n obtained in step S103 and the meter date tm _n−1 obtained from the previous timer 42 (Δt=tm _n −tm _n−1 ), the process proceeds to the next step S105.

As step S105, the engine stop time calculation unit 31 determines whether or not the difference time Δt calculated in step S104 is within a predetermined time range (−tc<Δt<tc). If the determination result is false (No), that is, if the difference time Δt is outside the predetermined time range, it is determined that the date and time of the timer 42 has been changed, and the process proceeds to step S106. On the other hand, if the determination result is true (Yes), it is determined that the date and time of the timer unit 42 has not been changed, and the process proceeds to step S107.

In step S106, the engine stop time calculation unit 31 adds the difference time Δt calculated in step S104 to the base date and time tbase stored in the storage unit 34 (subtraction when the difference time Δt is negative). This corrects the base date and time tbase. The engine stop time calculation unit 31 overwrites the storage unit 34 with the corrected base date and time tbase, and proceeds to step S107.

In step S107, the engine stop time calculation unit 31 calculates the time from the base date tbase stored in the storage unit 34 at this time to the meter date _tmn acquired in step S103 as the engine stop time tes (tes = tm _n - tbase).

As step S108, the fault diagnosis unit 32 determines whether or not the engine stop time tes calculated in step S107 has exceeded a predetermined stop time ta or more. If the determination result is false (No), that is, if the engine stop time tes is shorter than the predetermined stop time ta, it is determined that the engine 2 and the exhaust pipe 3 are not sufficiently cooled, and the sensor failure diagnosis is performed. Return the routine without doing anything. On the other hand, if the determination result is true (Yes), it is determined that the engine 2 and the exhaust pipe 3 are sufficiently cooled, and the process proceeds to the next step S110.

As step S109, the failure diagnosis unit 32 performs failure diagnosis of the SCR temperature sensor. The specific contents of the failure diagnosis are as described above, and when the sensor is normal without failure, the routine is returned as it is. On the other hand, if there is a failure in the sensor, the alarm generation unit 33 generates alarm information, the notification unit 44 issues an alarm, and the routine returns.

Next, FIG. 4 shows a time chart showing an example of the operation of the fault diagnosis device according to one embodiment of the present invention in chronological order. An operation example in this case will be described.

The time chart in the upper part of FIG. 4 shows, from the top, the ON/OFF state of the ignition key 43 (specifically, the ON operation, the ACC ON operation, the engine start operation, and the OFF operation), the starting/running of the engine 2 (during operation). • Stops are shown along the horizontal time axis. In the time chart in the lower part of FIG. 4, the vertical axis is the date and time t calculated by the control unit 30, the horizontal axis is the time axis (real time treal) on the same scale as the upper part, and the ignition key 43 and the engine 2 shown in the upper part. The time change of the engine stop time calculated by the control unit 30 according to the state is shown. Also, the dashed line perpendicular to the time axis indicates dates and times from t0 to t12.

From time t0 to time t1 in the time chart, the ignition key 43 is off, the engine 2 is also stopped, and at time t1 the ignition key 43 is on (ACC is turned on at this time). Although not shown, it is assumed that the base date and time tbase is set by the engine stop time calculator 31 when the engine is stopped before time t0.

At time t1 when the ignition key 43 is turned on, the control unit 30 performs activation processing such as reading various information and confirming communication. tes is counted (processing from S103 to S107 in FIG. 3). That is, from time t2, the engine stop time calculation unit 31 acquires the meter date and time tm from the clock unit 42 every predetermined cycle Cy, and adds the difference time Δt as the engine stop time tes. In addition, in FIG. 4, the period Cy is shown to be larger than the actual time interval for the purpose of understanding the invention.

At time t3, the ignition key 43 is operated to start the engine, and the engine 2 is started. Since the engine stop time tes1 at this point is less than the predetermined stop time ta (No in S108), the failure diagnosis unit 32 resets the base date and time tbase without executing the sensor failure diagnosis.

When the ignition key 43 is turned on at time t4 and the engine 2 is stopped (Yes in S101), the engine stop time calculator 31 stores the meter date and time tm at this time as the base date and time tbase (S102). . From time t4 to time t5, the engine stop time calculation section 31 counts the engine stop time tes as in the case from time t2 to time t3 (processing from S103 to S107).

At time t5, the ignition key 43 is turned off, power supply to the control unit 30 is stopped, and the engine stop time calculation unit 31 stops counting the engine stop time tes.

At time t6, the ignition key 43 is turned on (ACC ON operation), and when the activation process of the control unit 30 is completed at time t7, the engine stop time calculation unit 31 restarts counting the engine stop time tes.

Then, at time t8, the driver changes the date and time of the timer unit 42 . Therefore, the difference time Δt is out of the predetermined range (Yes in S105), and the engine stop time calculator 31 performs correction by adding the difference time Δt to the base date tbase (S106). In FIG. 4, the dashed-dotted line after time t8 indicates the new base date and time tbase, and the engine stop time calculator 31 counts the engine stop time tes based on the new base date and time tbase.

Specifically, from time t8 to time t9 when the ignition key 43 is in the ON state (ACC ON state), the engine stop time tes is counted (processing from S103 to S107 in FIG. 3), and the ignition key 43 is in the OFF state. The counting of the engine stop time tes is stopped from time t9 to time t10.

When the ignition key 43 is turned on (ACC on state) at time t10 and the activation process of the control unit 30 is completed at time t11, the engine stop time calculation unit 31 restarts counting the engine stop time tes.

At time t12, the ignition key 43 is operated to start the engine, and the engine 2 is started. At this time, the engine stop time tes2 is less than the predetermined stop time ta (No in S108), and the failure diagnosis section 32 executes sensor failure diagnosis and resets the base date and time tbase.

In FIG. 4, the dashed arrow indicates the case where the base date and time tbase is not corrected in response to the change in the date and time of the timer 42 at time t8. is greater than or equal to the predetermined stop time ta. In other words, if the base date and time tbase is not corrected due to the change in the date and time of the timer unit 42, the failure diagnosis is performed even though the cooling is insufficient and the failure diagnosis of the sensor cannot be performed based on the actual engine stop time. As a result, the reliability of failure diagnosis is lowered.

As described above, according to the fault diagnosis device 1 of the present embodiment, the date and time information is periodically obtained from the timekeeping unit 42 such as the clock of the meter unit, and the base date and time tbase is set when the engine 2 stops. Then, the elapsed date and time from the base date and time tbase is calculated as the engine stop time tes. Then, when the difference time Δt between the meter date tm n acquired from the timer unit 42 and the meter date tm _{n −1} acquired last time is outside the predetermined range, the difference time Δt is calculated relative to the base date tbase. By performing this correction, even if the driver changes the date and time of the clock unit 42 and the date and time information greatly changes, the base date and time tbase can be corrected appropriately. As a result, an accurate engine stop time tes can be calculated, and the reliability of failure diagnosis of the SCR temperature sensor 21 whose necessity is determined based on the engine stop time can be improved.

Although the description of the embodiment of the fault diagnosis device 1 according to the present invention is finished above, the aspect of the present invention is not limited to this embodiment. In the above description, the case of diagnosing the failure of the SCR temperature sensor has been described as an example, but the aspects of the present invention can also be applied to failure diagnosis of other temperature sensors.

The fault diagnosis device of the above embodiment detects that the meter unit including the clock unit 42 has been replaced while the engine 2 continues to be stopped, and detects the base date and time tbase stored in the storage unit 34. You may add a function to reset the . For example, a second time range wider than the predetermined time range for the difference time Δt is set, and when the ignition key 43 is turned on from off (t1, t6, t10 in FIG. 4). time point), if the difference time Δt is outside the second time range, the engine stop time calculation unit resets the base date and time tbase stored in the storage unit 34 . Normally, when the meter unit is replaced, the initial setting of the clock is, for example, 00:00 on January 1, 2000, because it deviates significantly from the actual date and time. If it is outside the time range, it is determined that the meter unit has been replaced, and the base date and time tbase is reset, thereby ensuring the reliability of failure diagnosis.

In the above-described embodiment, FIG. 4 illustrates an example in which the driver changes the date and time of the timekeeping unit to the positive side (time advances). A change to the minus side (the side where time returns) can also be handled. If the date and time change is on the negative side, the engine stop time calculation unit 31 determines that the difference time Δt calculated in step S103 of FIG. The difference time Δt is subtracted from the date and time tbase (the base date and time tbase is returned).

Reference Signs List 1: Fault diagnosis device 2: Engine 3: Exhaust pipe 4: Cooling circuit 5: In-vehicle communication path 10: Exhaust purification device 11: Front stage 12: Rear stage 21: SCR temperature sensor 22: Refrigerant temperature sensor 23: Outside air temperature sensor 30 : Control unit 31 : Engine stop time calculation unit 32 : Failure diagnosis unit 33 : Alarm generation unit 34 : Storage unit 41 : Engine state detection unit 42 : Clock unit 43 : Ignition key 44 : Notification unit

Claims (1)

A sensor failure diagnosis device for diagnosing a failure of a sensor mounted on a vehicle,
a clocking unit that clocks the date and time;
an engine state detection unit capable of detecting starting and stopping of the engine of the vehicle;
The date and time are acquired from the timing unit at a predetermined cycle, and the date and time acquired from the timing unit when the engine state detection unit detects that the engine has stopped is set as a base date and time, and after the engine has stopped, the date and time is changed from the base date and time. an engine stop time calculation unit that calculates the time until the date and time acquired from the clock unit as an engine stop time;
a failure diagnosis unit that executes a failure diagnosis of the sensor when the engine stop time has passed a predetermined stop time or more;
The engine stop time calculation unit corrects the base date and time according to the difference time when the difference time between the date and time obtained from the clock unit and the date and time obtained last time is outside a predetermined range. A sensor failure diagnosis device characterized by:

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