Sensor diagnostic device

Abstract

To determine a sensor abnormality at an early stage.SOLUTION: A sensor diagnosis device according to one embodiment is used for a vehicle having a first temperature sensor and a second temperature sensor and detects an abnormality of the first temperature sensor or the second temperature sensor. The sensor diagnosis device includes a control system which has a processor and a memory that are connected to each other in a communicable manner, and which determines a sensor abnormality on the basis of a detection temperature difference between the first temperature sensor and the second temperature sensor. The control system calculates a reduction speed of the first detection temperature on the basis of the first detection temperature detected by the first temperature sensor after the vehicle is stopped, and calculates the reduction speed of the second detection temperature on the basis of the second detection temperature detected by the second temperature sensor. The control system determines a sensor abnormality on the basis of the detection temperature difference when an absolute value of the reduction speed difference between the first detection temperature and the second detection temperature is less than a threshold.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a sensor diagnostic device used in a vehicle equipped with a first temperature sensor and a second temperature sensor.

Background Art

[0002] In vehicles such as automobiles, a plurality of temperature sensors are attached in order to detect the temperature of each part and use it for various controls. For example, as temperature sensors attached to a vehicle, there are a temperature sensor that detects the coolant temperature of an engine, a temperature sensor that detects the operating oil temperature of a transmission, a temperature sensor that detects the cell temperature of a battery, and the like. By the way, in order to appropriately control a vehicle equipped with a temperature sensor, it is necessary to make the temperature sensor function appropriately. Therefore, a diagnostic device has been developed that determines abnormalities in a temperature sensor by performing a so-called soak diagnosis or the like on the temperature sensor (see Patent Documents 1-3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, when performing a soak diagnosis on a temperature sensor, the temperatures detected by each temperature sensor are compared with those of the target object whose temperature is detected by each sensor, under the condition that the temperatures of the objects detected by each sensor are matched. In other words, in order to perform a soak diagnosis, it was necessary to allow a predetermined soak time to elapse after the vehicle stopped. However, since a long soak time of several hours is required to match the temperatures of the target objects, it was difficult to detect sensor abnormalities early.

[0005] The objective of this invention is to detect sensor abnormalities at an early stage. [Means for solving the problem]

[0006] One embodiment of a sensor diagnostic device is used in a vehicle equipped with a first temperature sensor and a second temperature sensor, and is a sensor diagnostic device for detecting abnormalities in the first temperature sensor or the second temperature sensor, comprising a processor and memory that are communicated with each other, and a control system that determines sensor abnormalities based on the temperature difference detected between the first temperature sensor and the second temperature sensor. do. The control system, after the vehicle has stopped, calculates the rate at which the first detected temperature decreases based on the first detected temperature detected by the first temperature sensor, and calculates the rate at which the second detected temperature decreases based on the second detected temperature detected by the second temperature sensor. Based on the changes between the first detected temperature and the second detected temperature, a reversal of the first detected temperature and the second detected temperature within a specified time after the vehicle stops is predicted, and if it is predicted that the first detected temperature and the second detected temperature will not reverse, When the absolute value of the difference in the rate of decrease between the first detected temperature and the second detected temperature falls below a threshold, based on the difference in detected temperatures Ku Sensor malfunction of judgement Start do. One embodiment of a sensor diagnostic device is used in a vehicle equipped with a first temperature sensor and a second temperature sensor, and is a sensor diagnostic device for detecting abnormalities in the first temperature sensor or the second temperature sensor, and includes a processor and memory that are communicated with each other, and a control system that determines sensor abnormalities based on the temperature difference detected by the first temperature sensor and the second temperature sensor. After the vehicle stops, the control system calculates the rate of decrease of the first detected temperature based on the first detected temperature detected by the first temperature sensor, and calculates the rate of decrease of the second detected temperature based on the second detected temperature detected by the second temperature sensor, and predicts the reversal of the first detected temperature and the second detected temperature within a specified time after the vehicle stops, based on the transition between the first detected temperature and the second detected temperature. If the control system predicts that the first detected temperature and the second detected temperature will not reverse, it will start determining a sensor abnormality based on the detected temperature difference when the absolute value of the difference in the rate of decrease between the first detected temperature and the second detected temperature falls below a threshold. On the other hand, if the control system predicts that the first detected temperature and the second detected temperature will reverse, it will start determining a sensor abnormality based on the detected temperature difference after a period of time longer than the specified time has elapsed since the vehicle stopped. [Effects of the Invention]

[0007] The control system determines a sensor malfunction based on the temperature difference between the first and second temperature sensors when the absolute value of the difference in the rate of decrease between the first and second detected temperatures falls below a threshold. This allows for early detection of sensor malfunctions. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of an electric vehicle in which a sensor diagnostic device, which is one embodiment of the present invention, is used. [Figure 2] This figure shows an example of a control system that constitutes a sensor diagnostic device. [Figure 3] This figure shows an example of the basic structure of each control unit. [Figure 4] This flowchart shows an example of the procedure for executing sensor diagnostic control by a control system. [Figure 5] This flowchart shows an example of the procedure for executing sensor diagnostic control by a control system. [Figure 6] This figure shows an example of the sensor temperature changes during sensor diagnostic control. [Figure 7] This figure shows an example of the sensor temperature changes during sensor diagnostic control. [Figure 8] This figure shows an example of the sensor temperature changes during sensor diagnostic control. [Figure 9] This diagram shows the conditions for diagnostic cases 1-9. [Figure 10] This figure shows the change in sensor temperature in diagnostic case 1. [Figure 11] This figure shows the change in sensor temperature in diagnostic case 2. [Figure 12] This figure shows the change in sensor temperature in diagnostic case 3. [Figure 13] This figure shows the change in sensor temperature in diagnostic case 4. [Figure 14] This figure shows the change in sensor temperature in diagnostic case 5. [Figure 15] This figure shows the change in sensor temperature in diagnostic case 6. [Figure 16] This figure shows the change in sensor temperature in diagnostic case 7. [Figure 17] This figure shows the change in sensor temperature in diagnostic case 8. [Figure 18]It is a diagram showing the transition of the sensor temperature in Diagnostic Case 9.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the following description, the same or substantially the same configurations and elements are denoted by the same reference numerals, and repeated descriptions are omitted.

[0010] [Vehicle Configuration] FIG. 1 is a diagram showing an example of an electric vehicle (vehicle) 11 in which a sensor diagnostic device 10 according to an embodiment of the present invention is used. FIG. 2 is a diagram showing an example of a control system 50 that constitutes the sensor diagnostic device 10. Note that the control system 50 shown in FIG. 2 functions not only as the control system 50 of the sensor diagnostic device 10 but also as the control system 50 of the electric vehicle 11. As shown in FIGS. 1 and 2, the electric vehicle 11 is provided with an electric axle 14 that drives the wheels 13. The electric axle 14 has a motor generator 15 and a differential mechanism 16. A differential mechanism 16 is connected to the rotor 17 of the motor generator 15 via a gear train 18. Also, wheels 13 are connected to an axle 19 extending from the differential mechanism 16.

[0011] An inverter 21 is connected to the stator 20 of the motor generator 15, and a battery pack 22 is connected to the inverter 21. The battery pack 22 is provided with two battery modules 30 and 40 connected in parallel to each other, and each battery module has a plurality of battery cells 31 and 41 connected in series to each other. Also, the battery pack 22 is provided with main relays 23 and 24 connected to the battery modules 30 and 40, and a battery control unit 25 that monitors the charge and discharge of the battery modules 30 and 40.

[0012] Furthermore, the battery pack 22 is equipped with current sensors 32 and 42 for detecting the charging and discharging current of the battery modules 30 and 40, voltage sensors 33 and 43 for detecting the voltage of the battery modules 30 and 40, and temperature sensors 34 and 44 for detecting the temperature of the battery modules 30 and 40. In other words, the battery pack 22 is equipped with a first temperature sensor 34 for detecting the temperature of battery module 30 and a second temperature sensor 44 for detecting the temperature of battery module 40. Thus, the electric vehicle 11 is equipped with a first temperature sensor 34 for detecting the temperature of battery module 30 and a second temperature sensor 44 for detecting the temperature of battery module 40.

[0013] [Control System] As shown in Figure 2, the electric vehicle 11 is equipped with a control system 50 consisting of multiple electronic control units for performing sensor diagnostic control (described later) and controlling the electric axle 14, battery pack 22, etc. The control system 50 includes the aforementioned battery control unit 25 and a motor control unit 51 for controlling the inverter 21. The control system 50 also includes a vehicle control unit 52 that outputs control signals to each of the control units 25 and 51. These control units 25, 51, and 52 are connected to each other so as to be able to communicate via an in-vehicle network 53 such as CAN (Controller Area Network).

[0014] Figure 3 shows an example of the basic structure of each control unit 25, 51, and 52. As shown in Figure 3, each control unit 25, 51, and 52 has a microcontroller 62 into which a processor 60 and main memory (memory) 61 are incorporated. A predetermined program is stored in the main memory 61, and the program is executed by the processor 60. The processor 60 and the main memory 61 are connected to each other so as to be able to communicate with each other. Note that the microcontroller 62 may incorporate multiple processors 60, and the microcontroller 62 may also incorporate multiple main memory 61.

[0015] Furthermore, each control unit 25, 51, and 52 is equipped with an input circuit 63, a drive circuit 64, a communication circuit 65, and an external memory 66, etc. The input circuit 63 converts signals input from various sensors into signals that can be input to the microcontroller 62. The drive circuit 64 generates drive signals for various devices such as the aforementioned electric axle 14 based on signals output from the microcontroller 62. The communication circuit 65 converts signals output from the microcontroller 62 into communication signals for other control units. The communication circuit 65 also converts communication signals received from other control units into signals that can be input to the microcontroller 62. In addition, the external memory 66, which consists of non-volatile memory, stores programs and various data.

[0016] The vehicle control unit 52 sets operating targets for the electric axle 14, etc., based on input information from each control unit 25, 51 and various sensors described later. It then generates control signals corresponding to the operating targets for the electric axle 14, etc., and outputs these control signals to each control unit 25, 51. Sensors connected to the vehicle control unit 52 include a vehicle speed sensor 70 for detecting the vehicle speed of the electric vehicle 11, an accelerator sensor 71 for detecting the amount of accelerator pedal operation, and a brake sensor 72 for detecting the amount of brake pedal operation. The vehicle control unit 52 is also connected to a start switch 73 that is operated by the driver when the control system 50 is started. The start switch 73 is also called an ignition switch.

[0017] The control system 50 has two control modes: an OFF mode that puts the electric vehicle 11 into a non-operational start / stop state, and an ON mode that puts the electric vehicle 11 into an operational start state. For example, when switching the control system 50 from OFF mode to ON mode, the driver presses the brake pedal and the start switch 73 while the parking brake (not shown) is engaged. This switches the control system 50 from OFF mode to ON mode. Also, when switching the control system 50 from ON mode to OFF mode, the driver presses the start switch 73 while the brake pedal is pressed and the parking brake is engaged. This switches the control system 50 from ON mode to OFF mode.

[0018] As mentioned above, the battery pack 22 is equipped with a first temperature sensor 34 for detecting the temperature of the battery module 30 and a second temperature sensor 44 for detecting the temperature of the battery module 40. In order to properly control the electric vehicle 11 equipped with this battery pack 22, it is necessary for the first temperature sensor 34 and the second temperature sensor 44 to function properly. Therefore, the battery control unit 25, which constitutes the control system 50, determines whether or not there is an abnormality in the first temperature sensor 34 or the second temperature sensor 44 by performing the sensor diagnostic control described later. As will be described later, the sensor diagnostic control continues even after the control system 50 is switched to OFF mode, so even if the control system 50 is switched to OFF mode, the battery control unit 25 and other components remain in an activated state.

[0019] [Sensor diagnostic control] The following describes the sensor diagnostic control performed by the control system 50. Figures 4 and 5 are flowcharts showing an example of the procedure for performing sensor diagnostic control by the control system 50. In the flowcharts shown in Figures 4 and 5, the components are connected at the points indicated by the symbol A. Each step shown in the flowcharts of Figures 4 and 5 represents a process performed by one or more processors 60 that constitute the control system 50. The sensor diagnostic control shown in Figures 4 and 5 is performed by the control system 50 at predetermined intervals after the control system 50 is started in ON mode.

[0020] <Decision start timing based on soak time> As shown in Figure 4, in step S10, it is determined whether the control mode has been switched from ON mode to OFF mode, that is, whether the electric vehicle 11 is controlled to be in a stop-start state where it cannot be driven. If it is determined in step S10 that the control mode is ON mode, charging and discharging of the battery pack 22 continues, and the routine is exited without initiating abnormality detection of the first temperature sensor 34 and the second temperature sensor 44. On the other hand, if it is determined in step S10 that the control mode is OFF mode, that is, if it is determined that the electric vehicle 11 is stopped, charging and discharging of the battery pack 22 stops, and the process proceeds to step S11, initiating abnormality detection of the first temperature sensor 34 and the second temperature sensor 44.

[0021] In step S11, the initial temperature Ta1 of the battery module 30 detected by the first temperature sensor 34, that is, the initial temperature Ta1 at the time of switching from ON mode to OFF mode, is acquired by the battery control unit 25. Similarly, in step S11, the initial temperature Tb1 of the battery module 40 detected by the second temperature sensor 44, that is, the initial temperature Tb1 at the time of switching from ON mode to OFF mode, is acquired by the battery control unit 25. In the following step S12, it is determined whether a predetermined sampling time (e.g., several tens of minutes) tia has elapsed. If it is determined in step S12 that the sampling time tia has elapsed, the process proceeds to step S13, where the update temperature Ta2 of the battery module 30 detected by the first temperature sensor 34 is acquired by the battery control unit 25, and the update temperature Tb2 of the battery module 40 detected by the second temperature sensor 44 is acquired by the battery control unit 25.

[0022] In the following step S14, the battery control unit 25 calculates an approximation line LA showing the trend of the first detected temperature of the first temperature sensor 34 (hereinafter referred to as sensor temperature TA) based on the initial temperature Ta1 and the update temperature Ta2. Similarly, in step S14, the battery control unit 25 calculates an approximation line LB showing the trend of the second detected temperature of the second temperature sensor 44 (hereinafter referred to as sensor temperature TB) based on the initial temperature Tb1 and the update temperature Tb2. In the following step S15, it is predicted whether the approximation lines LA and LB will intersect before a predetermined time t1b has elapsed since switching to OFF mode. In other words, it is predicted whether the sensor temperatures TA and TB will reverse positions before a predetermined time t1b has elapsed since switching to OFF mode.

[0023] In step S15, if it is predicted that the approximation lines LA and LB will intersect within a specified time t1b, the process proceeds to step S16, where it is determined whether a predetermined soak time (e.g., several hours) t1c has elapsed since switching to OFF mode. The soak time (standing time) t1c is set to be longer than the specified time t1b. In step S16, if it is determined that the soak time t1c has elapsed, the process proceeds to step S17, where the battery control unit 25 acquires the determination temperatures Taj and Tbj of the battery modules 30 and 40. Specifically, in step S17, the battery control unit 25 acquires the determination temperature Taj of the battery module 30 detected by the first temperature sensor 34, i.e., the sensor temperature TA at the time the soak time tic has elapsed. Similarly, in step S17, the battery control unit 25 acquires the determination temperature Tbj of the battery module 40 detected by the second temperature sensor 44, i.e., the sensor temperature TB at the time the soak time tic has elapsed.

[0024] Next, in step S18, the detected temperature difference ΔT, which is the difference between the determination temperature Taj and the determination temperature Tbj, is calculated. In the following step S19, it is determined whether the absolute value of the detected temperature difference ΔT is less than or equal to a predetermined temperature difference threshold (second temperature difference threshold) X2. If in step S19 it is determined that the absolute value of the detected temperature difference ΔT is less than or equal to the temperature difference threshold X2, the process proceeds to step S20, where it is determined that the first temperature sensor 34 and the second temperature sensor 44 are functioning normally. On the other hand, if in step S19 it is determined that the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X2, the process proceeds to step S21, where it is determined that there is an abnormality in either the first temperature sensor 34 or the second temperature sensor 44.

[0025] In other words, after a soak time tick has elapsed, the battery modules 30 and 40 have converged to almost the same temperature. Therefore, if both the first temperature sensor 34 and the second temperature sensor 44 are functioning normally, the sensor temperatures TA and TB will be close to each other. For this reason, if the absolute value of the detected temperature difference ΔT is determined to be less than or equal to the temperature difference threshold X2, the process proceeds to step S20, where the first temperature sensor 34 and the second temperature sensor 44 are determined to be functioning normally. On the other hand, if the absolute value of the detected temperature difference ΔT is determined to be greater than the temperature difference threshold X2, the process proceeds to step S21, where either the first temperature sensor 34 or the second temperature sensor 44 is determined to have an offset abnormality, deviating from the normal value. In step S21, for example, the temperature sensor with the offset abnormality may be identified by comparing the ambient temperature detected by an ambient temperature sensor (not shown) with the sensor temperatures TA and TB detected by the temperature sensors.

[0026] Figure 6 shows an example of the changes in sensor temperatures TA and TB during sensor diagnostic control. As shown in Figure 6 at time t1, when the control mode is switched to OFF mode, the initial temperatures Ta1 and Tb1 of sensor temperatures TA and TB are detected. Subsequently, as shown at time t2, after the sampling time tia has elapsed, the updated temperatures Ta2 and Tb2 of sensor temperatures TA and TB are detected. Then, by connecting the initial temperature Ta1 and the updated temperature Ta2 with a straight line, an approximation line LA showing the change in sensor temperature TA is obtained, and by connecting the initial temperature Tb1 and the updated temperature Tb2 with a straight line, an approximation line LB showing the change in sensor temperature TB is obtained. Then, it is predicted whether or not the approximation lines LA and LB intersect each other within a specified time tib.

[0027] In the example shown in Figure 6, at time t3 within the specified time tib, the approximation lines LA and LB are expected to intersect. Therefore, the determination of sensor abnormalities is initiated after waiting for the soak time tic to elapse. That is, as shown at time t4 in Figure 6, once the soak time tic has elapsed, the determination temperatures Taj and Tbj of the sensor temperatures TA and TB are detected. Then, based on the absolute value of the detected temperature difference ΔT, a sensor abnormality in the first temperature sensor 34 or the second temperature sensor 44 is determined. In other words, if the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X2, it is determined that an offset abnormality has occurred in the first temperature sensor 34 or the second temperature sensor 44, deviating from the normal value. On the other hand, if the absolute value of the detected temperature difference ΔT falls below the temperature difference threshold X2, both the first temperature sensor 34 and the second temperature sensor 44 are determined to be normal. In the example shown in Figure 6, as shown in the enlarged portion, the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X2, so it is determined that an offset abnormality has occurred in the first temperature sensor 34 or the second temperature sensor 44.

[0028] <Decision start timing based on the difference in the rate of decrease of sensor temperature> As shown in Figure 4, if it is predicted in step S15 that the approximation lines LA and LB will not intersect within the specified time t1b, the process proceeds from step S15 to step S22 in Figure 5, in order to determine the start timing of the determination using the decrease rates of sensor temperatures TA and TB, as will be described later. As shown in Figure 5, in step S22, the battery control unit 25 calculates the decrease rate Sa1 of sensor temperature TA based on the initial temperature Ta1, the update temperature Ta2, and the sampling time tia. Similarly, in step S22, the battery control unit 25 calculates the decrease rate Sb1 of sensor temperature TB based on the initial temperature Tb1, the update temperature Tb2, and the sampling time tia. In other words, in step S22, the decrease rate Sa1, which is the amount of change in sensor temperature TA per unit time, and the decrease rate Sb1, which is the amount of change in sensor temperature TB per unit time, are calculated.

[0029] Next, the process proceeds to step S23, where the speed difference (decrease speed difference) ΔS1, which is the difference between the decrease speed Sa1 and the decrease speed Sb1, is calculated. In the following step S24, it is determined whether the absolute value of the speed difference ΔS1 falls below a predetermined threshold Xa. If it is determined in step S24 that the absolute value of the speed difference ΔS1 falls below the threshold Xa, the process proceeds to step S25, where the battery control unit 25 acquires the determination temperatures Taj and Tbj of the battery modules 30 and 40. In other words, the situation in which the speed difference ΔS1 between the decrease speed Sa1 of the sensor temperature TA and the decrease speed Sb1 of the sensor temperature TB falls below the threshold Xa is a situation in which the decrease speeds of the sensor temperatures TA and TB, which decrease over time, are close to each other. In this case, the process proceeds to step S25, where the battery control unit 25 acquires the determination temperatures Taj and Tbj of the battery modules 30 and 40 in order to determine the sensor abnormality without waiting for the soak time tic.

[0030] Next, in step S26, the detected temperature difference ΔT, which is the difference between the determination temperature Taj and the determination temperature Tbj, is calculated. In the following step S27, it is determined whether the absolute value of the detected temperature difference ΔT is less than or equal to a predetermined temperature difference threshold (first temperature difference threshold) X1. Note that the temperature difference threshold X2 used in step S19 is smaller than the temperature difference threshold X1 used in step S27. If in step S27 it is determined that the absolute value of the detected temperature difference ΔT is less than or equal to the temperature difference threshold X1, the process proceeds to step S28, where it is determined that the first temperature sensor 34 and the second temperature sensor 44 are functioning normally. On the other hand, if in step S27 it is determined that the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X2, the process proceeds to step S29, where it is determined that there is an abnormality in either the first temperature sensor 34 or the second temperature sensor 44.

[0031] On the other hand, if it is determined in step S24 that the absolute value of the speed difference ΔS1 is greater than or equal to the threshold Xa, the process proceeds to step S30 to determine whether a predetermined sampling time tia has elapsed. If it is determined in step S30 that the sampling time tia has elapsed, the process proceeds to step S31, where the update temperature Tan of the battery module 30 detected by the first temperature sensor 34 is acquired, and the update temperature Tbn of the battery module 40 detected by the second temperature sensor 44 is acquired.

[0032] In the following step S31, the battery control unit 25 calculates the rate of decrease of the sensor temperature TA, San, based on the previous update temperature Ta2, the current update temperature Tan, and the sampling time tia. Similarly, in step S22, the battery control unit 25 calculates the rate of decrease of the sensor temperature TB, Sbn, based on the previous update temperature Tb2, the current update temperature Tbn, and the sampling time tia. In other words, in step S32, the rate of decrease San, which is the amount of change in the sensor temperature TA per unit time, is updated, and the rate of decrease Sbn, which is the amount of change in the sensor temperature TB per unit time, is updated.

[0033] Next, the process proceeds to step S33, where the speed difference (decrease speed difference) ΔSn, which is the difference between the deceleration speed San and the deceleration speed Sbn, is calculated. In the following step S34, it is determined whether the absolute value of the speed difference ΔSn falls below a predetermined threshold Xa. If it is determined in step S34 that the absolute value of the speed difference ΔSn falls below the threshold Xa, the process proceeds to step S25, where the battery control unit 25 acquires the determination temperatures Taj and Tbj of the battery modules 30 and 40. As mentioned above, if it is determined in step S27 that the absolute value of the detected temperature difference ΔT is less than or equal to the temperature difference threshold X1, the process proceeds to step S28, where it is determined that the first temperature sensor 34 and the second temperature sensor 44 are functioning normally. On the other hand, if it is determined in step S27 that the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X2, the process proceeds to step S29, where it is determined that an offset abnormality has occurred in either the first temperature sensor 34 or the second temperature sensor 44. Furthermore, if it is determined in step S34 that the absolute value of the velocity difference ΔSn is greater than or equal to the threshold Xa, then in steps S30 to S33, the updated temperature Tan, Tbn, the decrease rate San, Sbn, and the velocity difference ΔSn are updated each time the sampling time tia has elapsed.

[0034] Figures 7 and 8 show examples of the changes in sensor temperature TA and TB during sensor diagnostic control. Figure 7 shows a situation where no offset abnormality occurs, while Figure 8 shows a situation where an offset abnormality occurs.

[0035] As shown in Figure 7 at time t1, when the control mode is switched to OFF mode, the initial temperatures Ta1 and Tb1 of the sensor temperatures TA and TB are detected. Subsequently, as shown at time t2, after the sampling time tia has elapsed, the updated temperatures Ta2 and Tb2 of the sensor temperatures TA and TB are detected. Then, based on the initial temperature Ta1 and the updated temperature Ta2, the rate of decrease Sa1 of the sensor temperature TA is calculated, and based on the initial temperature Tb1 and the updated temperature Tb2, the rate of decrease Sb1 of the sensor temperature TB is calculated. In addition, based on the rate of decrease Sa1 and Sb1 of the sensor temperatures TA and TB, the rate difference ΔS1 of the decrease rates Sa1 and Sb1 is calculated. In the example shown in Figure 7, since the rate difference ΔS1 exceeds the threshold Xa, as shown at times t3 and t4, the decrease rates San and Sbn and the rate difference ΔSn are updated each time a predetermined sampling time tia has elapsed.

[0036] Then, as shown in Figure 7 at time t4, when the rate difference ΔS3 between the decreasing rates Sa3 and Sb3 falls below the threshold Xa, the abnormality detection of the first temperature sensor 34 and the second temperature sensor 44 is initiated. In other words, as shown in Figure 7 at time t4, the determination temperatures Taj and Tbj of the sensor temperatures TA and TB are detected. If the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X1, it is determined that an offset abnormality has occurred in either the first temperature sensor 34 or the second temperature sensor 44. On the other hand, if the absolute value of the detected temperature difference ΔT falls below the temperature difference threshold X1, it is determined that the first temperature sensor 34 and the second temperature sensor 44 are normal. In the example shown in Figure 7, as shown in the enlarged portion, the absolute value of the detected temperature difference ΔT falls below the temperature difference threshold X1, so it is determined that the first temperature sensor 34 and the second temperature sensor 44 are normal.

[0037] Furthermore, as shown in Figure 8 at time t1, when the control mode is switched to OFF mode, the initial temperatures Ta1 and Tb1 of the sensor temperatures TA and TB are detected. Subsequently, as shown in time t2, after the sampling time tia has elapsed, the updated temperatures Ta2 and Tb2 of the sensor temperatures TA and TB are detected. Then, based on the initial temperature Ta1 and the updated temperature Ta2, the rate of decrease Sa1 of the sensor temperature TA is calculated, and based on the initial temperature Tb1 and the updated temperature Tb2, the rate of decrease Sb1 of the sensor temperature TB is calculated. In addition, based on the rate of decrease Sa1 and Sb1 of the sensor temperatures TA and TB, the rate difference ΔS1 of the rate of decrease Sa1 and Sb1 is calculated. In the example shown in Figure 8, since the rate difference ΔS1 exceeds the threshold Xa, as shown in times t3 and t4, the rate of decrease San and Sbn and the rate difference ΔSn are updated each time a predetermined sampling time tia has elapsed.

[0038] Then, as shown in Figure 8 at time t4, when the rate difference ΔS3 between the decreasing rates Sa3 and Sb3 falls below the threshold Xa, the abnormality detection of the first temperature sensor 34 and the second temperature sensor 44 is initiated. In other words, as shown in Figure 8 at time t4, the determination temperatures Taj and Tbj of the sensor temperatures TA and TB are detected. If the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X1, it is determined that an offset abnormality has occurred in either the first temperature sensor 34 or the second temperature sensor 44. On the other hand, if the absolute value of the detected temperature difference ΔT falls below the temperature difference threshold X1, it is determined that both the first temperature sensor 34 and the second temperature sensor 44 are normal. In the example shown in Figure 8, as shown in the enlarged portion, the absolute value of the detected temperature difference ΔT exceeds the temperature difference threshold X1, so it is determined that an offset abnormality has occurred in either the first temperature sensor 34 or the second temperature sensor 44.

[0039] As explained using Figures 7 and 8, the situation in which the rate difference ΔSn between the decrease rates San and Sbn falls below the threshold Xa is a situation in which the decrease rates of the sensor temperatures TA and TB, which decrease over time, are close to each other. In other words, it is a situation in which the decrease rates San and Sbn of the sensor temperatures TA and TB do not diverge significantly, and the detected temperature difference ΔT between the sensor temperatures TA and TB decreases stably without sudden changes. For this reason, without waiting for the aforementioned soak time tick to elapse, abnormality detection of the first temperature sensor 34 and the second temperature sensor 44 is initiated based on the detected temperature difference ΔT between the sensor temperatures TA and TB. As a result, as shown by arrow α in Figures 7 and 8, the timing of the determination can be started much earlier compared to waiting for the soak time tick to elapse, and sensor abnormalities can be detected earlier.

[0040] [Diagnostic Cases 1-9] Next, we will explain various diagnostic cases 1-9 in sensor diagnostic control. Figure 9 shows the situation for each diagnostic case 1-9. Figure 10 shows the changes in sensor temperature TA and TB in diagnostic case 1, Figure 11 shows the changes in sensor temperature TA and TB in diagnostic case 2, and Figure 12 shows the changes in sensor temperature TA and TB in diagnostic case 3. Furthermore, Figure 13 shows the changes in sensor temperature TA and TB in diagnostic case 4, Figure 14 shows the changes in sensor temperature TA and TB in diagnostic case 5, and Figure 15 shows the changes in sensor temperature TA and TB in diagnostic case 6. In addition, Figure 16 shows the changes in sensor temperature TA and TB in diagnostic case 7, Figure 17 shows the changes in sensor temperature TA and TB in diagnostic case 8, and Figure 18 shows the changes in sensor temperature TA and TB in diagnostic case 9.

[0041] <Diagnosis Cases 1-3> Diagnostic cases 1-3 are described below. As shown in Figure 9, diagnostic cases 1-3 are situations in which no offset abnormalities occur for the first and second temperature sensors 34 and 44. In diagnostic case 1, the initial temperature Ta1 is higher than the initial temperature Tb1; in diagnostic case 2, the initial temperature Ta1 is lower than the initial temperature Tb1; and in diagnostic case 3, the initial temperatures Ta1 and Tb1 are equal.

[0042] As shown in Figure 10, in diagnostic case 1, as shown at time t1, the initial temperature Ta1 is higher than the initial temperature Tb1, and as shown at time t4, the sensor temperatures TA and TB are almost the same after the soak time tic has elapsed. In other words, the amount of temperature decrease of sensor temperature TA is greater than the amount of temperature decrease of sensor temperature TB, so the rate of decrease of sensor temperature TA is faster than the rate of decrease of sensor temperature TB, and the difference in the rate of decrease of sensor temperatures TA and TB ΔS is on the positive side. In diagnostic case 1, as shown at time t2, the absolute value of the rate of decrease difference ΔS is below the threshold Xa, so at time t3, after the sampling time tia has elapsed, the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and sensor abnormalities can be detected earlier.

[0043] As shown in Figure 11, in diagnostic case 2, as shown at time t1, the initial temperature Ta1 is lower than the initial temperature Tb1, and as shown at time t4, the sensor temperatures TA and TB are almost the same after the soak time tic has elapsed. In other words, the amount of temperature decrease of sensor temperature TB is greater than the amount of temperature decrease of sensor temperature TA, so the rate of decrease of sensor temperature TB is faster than the rate of decrease of sensor temperature TA, and the difference in the rate of decrease of sensor temperatures TA and TB, ΔS, is on the negative side. In diagnostic case 2, as shown at time t2, the absolute value of the rate of decrease difference ΔS is below the threshold Xa, so at time t3, after the sampling time tia has elapsed, the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and sensor abnormalities can be detected earlier.

[0044] As shown in Figure 12, in diagnostic case 3, as shown at time t1, the initial temperature Ta1 and initial temperature Tb1 are the same, and as shown at time t3, the sensor temperatures TA and TB are almost the same after the soak time tic has elapsed. In other words, since the amount of temperature decrease of sensor temperatures TA and TB is almost the same, the rate of decrease of sensor temperatures TA and TB is almost the same, and the difference in the rate of decrease of sensor temperatures TA and TB ΔS is near zero. In diagnostic case 3, at time t2 after the sampling time tia has elapsed, the absolute value of the rate of decrease difference ΔS falls below the threshold Xa, so the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and sensor abnormalities can be detected earlier.

[0045] <Diagnostic Case 4-6> Diagnostic cases 4-6 will now be explained. As shown in Figure 9, diagnostic case 4-6 is a situation in which a lower offset anomaly occurs with respect to the second temperature sensor 44. Furthermore, in diagnostic case 4, the initial temperature Ta1 is higher than the initial temperature Tb1, in diagnostic case 5, the initial temperature Ta1 is lower than the initial temperature Tb1, and in diagnostic case 6, the initial temperatures Ta1 and Tb1 are equal.

[0046] As shown in Figure 13, in diagnostic case 4, as shown at time t1, the initial temperature Ta1 is higher than the initial temperature Tb1, and as shown at time t4, after the soak time tic has elapsed, the sensor temperature TA is higher than the sensor temperature TB. In other words, since there is no significant difference in the amount of temperature decrease between sensor temperatures TA and TB, the rate of decrease between sensor temperatures TA and TB is almost the same, and the difference in the rate of decrease between sensor temperatures TA and TB, ΔS, is near zero. In diagnostic case 4, at time t2, after the sampling time tia has elapsed, the absolute value of the rate of decrease difference ΔS falls below the threshold Xa, and the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and sensor abnormalities can be detected earlier.

[0047] As shown in Figure 14, in diagnostic case 5, as shown at time t1, the initial temperature Ta1 is lower than the initial temperature Tb1, and as shown at time t3, after the soak time tic has elapsed, the sensor temperature TA is higher than the sensor temperature TB. In other words, the amount of temperature decrease of sensor temperature TB is significantly larger than the amount of temperature decrease of sensor temperature TA, so the rate of decrease of sensor temperature TB is significantly faster than the rate of decrease of sensor temperature TA, and the difference in the rate of decrease of sensor temperatures TA and TB, ΔS, is large on the negative side. Thus, in diagnostic case 5, where the rate of decrease difference ΔS is large, it is predicted that the sensor temperatures TA and TB will reverse midway, as shown at time t2. In this case, since it is difficult to set the timing for starting the judgment based on the rate of decrease difference ΔS, the abnormality judgment of the first and second temperature sensors 34 and 44 is started at time t3, after the soak time tic has elapsed. This allows the sensor temperatures TA and TB to stabilize over the soak time tic, and the sensor abnormality can be appropriately determined.

[0048] As shown in Figure 15, in diagnostic case 6, as shown at time t1, the initial temperatures Ta1 and Tb1 are the same, and as shown at time t4, after the soak time tic has elapsed, the sensor temperature TA is higher than the sensor temperature TB. In other words, the amount of temperature decrease of sensor temperature TB is greater than the amount of temperature decrease of sensor temperature TA, so the rate of decrease of sensor temperature TB is faster than the rate of decrease of sensor temperature TA, and the difference in the rate of decrease of sensor temperatures TA and TB ΔS is on the negative side. In diagnostic case 6, as shown at time t2, the absolute value of the rate of decrease difference ΔS is below the threshold Xa, so at time t3, after the sampling time tia has elapsed, the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and the sensor abnormality can be detected earlier.

[0049] <Diagnostic Case 7-9> Diagnostic cases 7-9 will now be explained. As shown in Figure 9, diagnostic case 7-9 is a situation in which an upper offset abnormality occurs with respect to the second temperature sensor 44. Furthermore, in diagnostic case 7, the initial temperature Ta1 is higher than the initial temperature Tb1, in diagnostic case 8, the initial temperature Ta1 is lower than the initial temperature Tb1, and in diagnostic case 9, the initial temperatures Ta1 and Tb1 are equal.

[0050] As shown in Figure 16, in diagnostic case 7, as shown at time t1, the initial temperature Ta1 is higher than the initial temperature Tb1, and as shown at time t3, after the soak time tic has elapsed, the sensor temperature TA is lower than the sensor temperature TB. In other words, the amount of temperature decrease of sensor temperature TA is significantly larger than the amount of temperature decrease of sensor temperature TB, so the rate of decrease of sensor temperature TA is significantly faster than the rate of decrease of sensor temperature TB, and the difference in the rate of decrease of sensor temperatures TA and TB, ΔS, is large on the positive side. Thus, in diagnostic case 7, where the rate of decrease difference ΔS is large, it is predicted that the sensor temperatures TA and TB will reverse midway, as shown at time t2. In this case, since it is difficult to set the timing for starting the judgment based on the rate of decrease difference ΔS, the abnormality judgment of the first and second temperature sensors 34 and 44 is started at time t3, after the soak time tic has elapsed. This allows the sensor temperatures TA and TB to stabilize over the soak time tic, and the sensor abnormality can be appropriately determined.

[0051] As shown in Figure 17, in diagnostic case 8, as shown at time t1, the initial temperature Ta1 is lower than the initial temperature Tb1, and as shown at time t3, after the soak time tic has elapsed, the sensor temperature TA is lower than the sensor temperature TB. In other words, since there is no significant difference in the amount of temperature decrease between sensor temperatures TA and TB, the rate of decrease between sensor temperatures TA and TB is almost the same, and the difference in the rate of decrease between sensor temperatures TA and TB, ΔS, is near zero. In diagnostic case 8, at time t2, after the sampling time tia has elapsed, the absolute value of the rate of decrease difference ΔS falls below the threshold Xa, and the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and sensor abnormalities can be detected earlier.

[0052] As shown in Figure 18, in diagnostic case 9, as shown at time t1, the initial temperatures Ta1 and Tb1 are the same, and as shown at time t4, after the soak time tic has elapsed, the sensor temperature TB is higher than the sensor temperature TA. In other words, the amount of temperature decrease of sensor temperature TA is greater than the amount of temperature decrease of sensor temperature TB, so the rate of decrease of sensor temperature TA is faster than the rate of decrease of sensor temperature TB, and the difference in the rate of decrease of sensor temperatures TA and TB ΔS is on the positive side. In diagnostic case 9, as shown at time t2, the absolute value of the rate of decrease difference ΔS is below the threshold Xa, so at time t3, after the sampling time tia has elapsed, the abnormality detection of the first and second temperature sensors 34 and 44 is initiated. As a result, as shown by arrow α, the timing of the start of the detection can be significantly earlier compared to waiting for the soak time tic to elapse, and the sensor abnormality can be detected earlier.

[0053] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. In the above description, an electric vehicle 11 is given as an example of a vehicle equipped with a first temperature sensor 34 and a second temperature sensor 44, but the invention is not limited to this. For example, the sensor diagnostic device 10 of this embodiment may be applied to a vehicle equipped only with an engine as a power source. Alternatively, for example, the sensor diagnostic device 10 of this embodiment may be applied to a vehicle equipped with an engine and a motor generator as power sources. Furthermore, the control system 50 that performs sensor diagnostic control may be a control system composed of one control unit, or a control system composed of multiple control units.

[0054] In the above description, sensor diagnostic control is performed by the sensor diagnostic device 10 with respect to the first temperature sensor 34 and the second temperature sensor 44 provided on the battery pack 22, but it is not limited to this. In other words, the temperature sensor that is the target of sensor diagnostic control may be, for example, a temperature sensor that detects the engine coolant temperature, a temperature sensor that detects the transmission fluid temperature, or a temperature sensor that detects the engine intake air temperature. Also, the objects whose temperature is detected by the first temperature sensor and the second temperature sensor may be the same object, or they may be different objects. In other words, they may be different objects as long as they are cooled to the same temperature after the vehicle is stopped. Furthermore, the type of temperature sensor that is the target of sensor diagnostic control may be any type. For example, it may be a temperature sensor composed of a thermistor, a temperature sensor composed of a semiconductor element, or a temperature sensor composed of a thermocouple.

[0055] As shown in the flowchart of Figure 5, in step S22, the decrease rates Sa1 and Sb1 of the sensor temperatures TA and TB are calculated, and in step S32, the decrease rates San and Sbn of the sensor temperatures TA and TB are calculated. In steps S22 and S32, the decrease rates Sa1 and San may be calculated by differentiating the sensor temperature TA, or by differentiating the sensor temperature TA. Furthermore, as shown in Figure 6, the reversal of the sensor temperatures TA and TB is predicted using linear approximation lines LA and LB, but this is not the only method, and the reversal of the sensor temperatures TA and TB may be predicted using other approximation curves. [Explanation of Symbols]

[0056] 10 Sensor diagnostic device 11. Electric Vehicles (Vehicles) 34. First temperature sensor 44. Second temperature sensor 50 Control Systems 60 processors 61 Main memory (memory) TA sensor temperature (first detection temperature) TB sensor temperature (second detection temperature) ΔT Detected temperature difference Sa1,Sa2,Sa3,San Decrease speed Sb1,Sb2,Sb3,Sbn Decrease rate ΔS1, ΔS2, ΔS3, ΔSn, ΔS Decrease speed difference Xa threshold X1 Temperature difference threshold (first temperature difference threshold) X2 Temperature difference threshold (second temperature difference threshold) tib specified time tic soak time (leaving time)

Claims

1. A sensor diagnostic device used in a vehicle equipped with a first temperature sensor and a second temperature sensor, for detecting abnormalities in the first temperature sensor or the second temperature sensor, The system includes a processor and memory that are connected to each other in a manner that enables communication, and a control system that determines a sensor abnormality based on the temperature difference detected between the first temperature sensor and the second temperature sensor. The control system is After the aforementioned vehicle has come to a stop, Based on the first detected temperature detected by the first temperature sensor, the rate of decrease of the first detected temperature is calculated, and based on the second detected temperature detected by the second temperature sensor, the rate of decrease of the second detected temperature is calculated. Based on the changes between the first detected temperature and the second detected temperature, the reversal of the first detected temperature and the second detected temperature within a specified time after the vehicle stops is predicted. If it is predicted that the first detected temperature and the second detected temperature will not reverse, the determination of a sensor abnormality based on the detected temperature difference is initiated when the absolute value of the difference in the rate of decrease between the first detected temperature and the second detected temperature falls below a threshold. Sensor diagnostic device.

2. In the sensor diagnostic device according to claim 1, The control system is If it is predicted that the first detected temperature and the second detected temperature will reverse, the determination of a sensor abnormality based on the difference in detected temperatures will be initiated after a period of time longer than the specified time has elapsed since the vehicle stopped. Sensor diagnostic device.

3. A sensor diagnostic device used in a vehicle equipped with a first temperature sensor and a second temperature sensor, for detecting abnormalities in the first temperature sensor or the second temperature sensor, The system includes a processor and memory that are connected to each other in a manner that enables communication, and a control system that determines a sensor abnormality based on the temperature difference detected between the first temperature sensor and the second temperature sensor. The control system is After the aforementioned vehicle has come to a stop, Based on the first detected temperature detected by the first temperature sensor, the rate of decrease of the first detected temperature is calculated, and based on the second detected temperature detected by the second temperature sensor, the rate of decrease of the second detected temperature is calculated. Based on the changes between the first detected temperature and the second detected temperature, the reversal of the first detected temperature and the second detected temperature within a specified time after the vehicle stops is predicted. The control system is If it is predicted that the first detected temperature and the second detected temperature will not reverse, the determination of a sensor abnormality based on the detected temperature difference is initiated when the absolute value of the difference in the rate of decrease between the first detected temperature and the second detected temperature falls below a threshold, If it is predicted that the first detected temperature and the second detected temperature will reverse, the determination of a sensor abnormality based on the difference in detected temperatures will be initiated after a period of time longer than the specified time has elapsed since the vehicle stopped. Sensor diagnostic device.

4. In the sensor diagnostic device according to claim 2 or 3, The control system is When determining a sensor malfunction based on the absolute value of the rate of decrease falling below the threshold, it is determined that a sensor malfunction has occurred if the absolute value of the detected temperature difference exceeds the first temperature difference threshold. When the determination of a sensor abnormality is initiated after the aforementioned waiting period has elapsed, a sensor abnormality is determined to have occurred if the absolute value of the detected temperature difference exceeds a second temperature difference threshold that is smaller than the first temperature difference threshold. Sensor diagnostic device.

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