Diagnosis device and diagnosis method for temperature sensor of automatic transmission

Abstract

A substrate temperature sensor as an AT control unit (10) has a main substrate temperature sensor (31) and a sub-substrate temperature sensor (32) as substrate temperature sensors of an AT control unit (10). A substrate temperature sensor diagnosis controller (100) assesses whether or not a main temperature sensor value (MA1) and a sub-temperature sensor value (SUB1) have diverged by at least a prescribed value, and upon assessing that a state of divergence by at least a prescribed value is continually ongoing for at least a prescribed time, diagnoses that one of the substrate temperature sensors (31, 32) has an anomaly. For a prescribed interval depending on a predetermined condition after the anomaly diagnosis, a torque limit is imposed, the torque limit limiting input torque from an engine (1) to an automatic transmission (3). When the anomaly detection of the substrate temperature sensors (31, 32) is ongoing even when the prescribed interval has ended, transmission limiting of the automatic transmission (3) is performed in addition to the imposing of the torque limit.

Description

technical field [0001] The present invention relates to a temperature sensor diagnosis device and a diagnosis method of an automatic transmission mounted on a vehicle. Background technique [0002] Conventionally, as a control device for a vehicle equipped with an automatic transmission, a well-known vehicle control device includes: a transmission cooling system diagnostic unit that compares the transmission oil temperature with a judgment threshold to diagnose abnormalities in the transmission cooling system; The transmission cooling system diagnosis means changes the shift mode of the automatic transmission to a high speed side or fixes it to a predetermined level when the transmission cooling system is diagnosed to be abnormally high temperature (see Patent Document 1). [0003] In the conventional device described above, it is impossible to determine whether the temperature is high when the temperature sensor fails, so it is considered to be fixed at a predetermined gear...

AI Technical Summary

Problems solved by technology

However, when diagnosing malfunctions by comparing the values ​​of two sensors, double failures cannot be detected because the comparison object has already failed at the time of abnormality diagnosis.

However, if the abnormality countermeasure based on the speed change restriction is immediately started from the time when the abnormality of the temperature sensor is diagnosed, the drivability at the time of failure will be deteriorated.

On the other hand, if the standby is performed so that the abnormality countermeasures based on the speed change limitation are not entered even if a functional abnormality is diagnosed, if a double fault occurs during the standby, since the functional abnormality of the second temperature sensor cannot be detected, Therefore, it is impossible to shift to a limp home fixed at a predetermined gear, and the state of the automatic transmission deteriorates, which may increase the discomfort to the driver.

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