JP2012052633A

JP2012052633A - Failure determining device of oil temperature sensor

Info

Publication number: JP2012052633A
Application number: JP2010197349A
Authority: JP
Inventors: Ryuji Ito; 隆二伊藤; Hiroyuki Kamatsuki; 裕之釜付
Original assignee: Suzuki Motor Corp
Current assignee: Suzuki Motor Corp
Priority date: 2010-09-03
Filing date: 2010-09-03
Publication date: 2012-03-15

Abstract

PROBLEM TO BE SOLVED: To determine failure of an oil temperature sensor according to a condition of a vehicle at an early stage, and to reduce incorrect determination, in a failure determining device of the oil temperature sensor.SOLUTION: A failure determining section (25) includes an oil temperature estimating part (25A) which estimates oil temperature (To0) of an automatic transmission (2) from an engine temperature (Te) to find an estimated oil temperature (Tx), a failure determination threshold value deciding part (25B) which decides a failure determination threshold value (C1) for determining that the oil temperature sensor (8) is out of order, and a failure index determining section (25C) which finds failure indexes (degree of failure (Cu), degree of normality (Cd)) being larger as getting larger oil temperature difference (ΔT) between the estimated oil temperature (Tx) found by the oil temperature estimating part (25A) and the oil temperature (To0) detected by the oil temperature sensor (8). When a count number (Co) which is sum of a plurality of failure indexes found by every predetermined period reaches the failure determination threshold value (C1), it is determined that the oil temperature sensor (8) is out of order.

Description

この発明は、油温センサの故障判定装置に係り、特に自動変速機の油温を検出する油温センサの故障判定を車両の状況に応じて早期に行う油温センサの故障判定装置に関する。 The present invention relates to a failure determination device for an oil temperature sensor, and more particularly, to a failure determination device for an oil temperature sensor that performs failure determination of an oil temperature sensor that detects an oil temperature of an automatic transmission at an early stage according to the state of the vehicle.

車両に搭載した自動変速機においては、油温を検出する油温センサが設けられており、この油温センサの検出した油温に基づいて最適な変速制御を可能としている。油温センサの故障は、最適な変速制御を阻害するものであり、早期に故障判断がなされるべきである。
油温センサの故障診断方法の―つとして、所定の走行時間後に油温を確認し、この油温が所定温度以下であれば故障と判断する方法がある。 In an automatic transmission mounted on a vehicle, an oil temperature sensor for detecting an oil temperature is provided, and optimal shift control is possible based on the oil temperature detected by the oil temperature sensor. The failure of the oil temperature sensor hinders the optimum shift control, and the failure should be determined at an early stage.
As one of the failure diagnosis methods for the oil temperature sensor, there is a method in which the oil temperature is confirmed after a predetermined traveling time, and a failure is determined if the oil temperature is equal to or lower than a predetermined temperature.

特開２００６−１７７４１２号公報JP 2006-177412 A

上記の特許文献１に係る自動変速機の油温センサ故障検出装置は、走行時間ｔが所定の期間ｔａを経過したときに、油温センサ（Ａ／Ｔ油温センサ）で検出される油温ＴＯが、自動変速機の変速動作の制御を開始する制御開始油温Ｔ＿ｃｒｉを含む所定の温度範囲内にないことに基づいて、油温センサを故障と判断するものであって、走行時間ｔが所定の期間ｔａを経過すれば、油温ＴＯが制御開始油温Ｔ＿ｃｒｉを含む所定の温度範囲にあるはずが、その温度範囲とは異なる油温が検出されたことで、油温センサが故障していると判断するものである。 The oil temperature sensor failure detection device for an automatic transmission according to Patent Document 1 described above detects an oil temperature detected by an oil temperature sensor (A / T oil temperature sensor) when the traveling time t has passed a predetermined period ta. Based on the fact that TO is not within a predetermined temperature range including the control start oil temperature T_cri for starting the control of the shift operation of the automatic transmission, the oil temperature sensor is determined to be in failure, and the running time t is If the predetermined period ta has elapsed, the oil temperature TO should be within a predetermined temperature range including the control start oil temperature T_cri, but an oil temperature different from that temperature range has been detected, and the oil temperature sensor has failed. It is judged that it is.

ところで、上記の特許文献１では、油温センサの故障検出にあたり、所定の期間ｔａを一律に油温ＴＯが制御開始油温Ｔ＿ｃｒｉに達するか否かで油温センサの故障を判定していた。
しかし、車両の走行状態によっては、油温ＴＯが比較的高温の場合もあり、この場合には、油温ＴＯが極低温Ｔ＿ａの場合よりも油温ＴＯが制御開始油温Ｔ＿ｃｒｉに達する時間も短い。
そして、油温センサの故障判定を行うのに、油温ＴＯが極低温Ｔ＿ａと同一の場合と同じ所定の期間ｔａの経過を待ってから油温センサの故障判定を行うことは、油温センサの故障判定に要する時間が必要以上に長く、また、走行時間ｔが所定の期間ｔａよりも短いような場合に油温センサの故障検出を行うことができなかった。
そのため、所定の極低温Ｔ＿ａを最小値とし、かつ制御開始油温Ｔ＿ｃｒｉを最大値として、段階的に増加する複数の初期油温Ｔ＿ａ１〜Ｔ＿ａ４における走行時間ｔの経過に伴う油温上昇マップデータを準備しておき、初期油温に応じて油温センサの故障と判定するまでの時間を可変としている。
これにより、初期油温が高温であればあるほど、油温センサの故障判定に要する時間を少なくでき、故障判定頻度を上げることができる。
しかしながら、上記の特許文献１では、車両の走行状態は様々であり、事前に設定された温度上昇マップデータとは異なる温度上昇となる場合があり、このため、誤った判定結果を招く原因にもなっていた。
よって、常に、車両の走行状況をみて、早期に油温センサの故障判断がなされることが望まれていた。 By the way, in Patent Document 1 described above, when detecting a failure of the oil temperature sensor, the failure of the oil temperature sensor is determined by whether or not the oil temperature TO reaches the control start oil temperature T_cri uniformly over a predetermined period ta.
However, depending on the traveling state of the vehicle, the oil temperature TO may be relatively high. In this case, the time during which the oil temperature TO reaches the control start oil temperature T_cri is also greater than when the oil temperature TO is extremely low temperature T_a. short.
In order to determine the failure of the oil temperature sensor, the failure determination of the oil temperature sensor is performed after waiting for the elapse of the same predetermined period ta as when the oil temperature TO is the same as the cryogenic temperature T_a. The failure detection of the oil temperature sensor could not be performed when the time required for the failure determination is longer than necessary and the traveling time t is shorter than the predetermined period ta.
Therefore, the oil temperature increase map data with the passage of the running time t at a plurality of initial oil temperatures T_a1 to T_a4 that increase in stages with the predetermined cryogenic temperature T_a as the minimum value and the control start oil temperature T_cri as the maximum value. The time until it is determined that the oil temperature sensor has failed is made variable according to the initial oil temperature.
As a result, the higher the initial oil temperature, the less time is required for the failure determination of the oil temperature sensor, and the failure determination frequency can be increased.
However, in the above-mentioned Patent Document 1, the running state of the vehicle is various, and there is a case where the temperature rise is different from the preset temperature rise map data, which may cause an erroneous determination result. It was.
Therefore, it has been desired to always determine the failure of the oil temperature sensor at an early stage by looking at the traveling state of the vehicle.

また、現在、油温センサの低温固着故障診断ロジックは、ある一定の診断時間経過後、ある閾値温度を超えていなければ故障と判断し、ある閾値温度以上であれば、正常と判断している。また、故障の誤検出を避けるために、走行時の油温の上昇率が低い極低温環境を想定して、ある一定の診断時間は決定されている。
しかし、暑い天候の地域や登坂路を走行したときには、極低温環境の走行と比較し油温が上昇しやすい傾向にあるため、故障と診断するまでの診断時間が長くなるという不都合があった。 Also, at present, the low temperature fixing failure diagnosis logic of the oil temperature sensor determines that a failure has occurred if a certain threshold temperature has not been exceeded after a certain diagnosis time has passed, and is determined to be normal if it has exceeded a certain threshold temperature. . In order to avoid erroneous detection of a failure, a certain diagnosis time is determined on the assumption of a cryogenic environment in which the rate of increase in oil temperature during traveling is low.
However, when traveling on a hot weather area or on an uphill road, the oil temperature tends to rise more easily than traveling in a cryogenic environment, so there is a disadvantage that the diagnosis time until a failure is diagnosed becomes longer.

そこで、この発明の目的は、車両の状況に応じた油温センサの故障判定を早期に行えるとともに、誤判定を軽減可能な油温センサの故障判定装置を提供することにある。 SUMMARY OF THE INVENTION An object of the present invention is to provide an oil temperature sensor failure determination device capable of early determination of an oil temperature sensor failure according to a vehicle condition and reducing erroneous determination.

この発明は、車両の動力源であるエンジンを設け、このエンジンの出力を前記車両の駆動輪に伝える自動変速機を設け、前記エンジンの温度を検出するエンジン温度検出手段を設け、前記自動変速機の油温を検出する油温センサを設け、この油温センサの故障を判定する故障判定部を備える制御手段を設けた車両の油温センサの故障判定装置において、前記故障判定部は、前記エンジン温度検出手段のエンジン温度の検出結果から前記自動変速機の油温を推定して推定油温を求める油温推定部と、前記油温センサが故障していると判定するための故障判定閾値を決定する故障判定閾値決定部と、前記油温推定部が求めた推定油温と前記油温センサの検出油温との油温差が大きいほど大となる故障指数を求める故障指数決定部とを備え、所定時間毎に求められる複数の前記故障指数の合計であるカウント数が前記故障判定閾値に達することで前記油温センサが故障していると判定することを特徴とする。 The present invention includes an engine that is a power source of a vehicle, an automatic transmission that transmits an output of the engine to a drive wheel of the vehicle, an engine temperature detection unit that detects the temperature of the engine, and the automatic transmission. In the vehicle oil temperature sensor failure determination device provided with a control means including a failure determination unit for determining an oil temperature sensor failure and determining a failure of the oil temperature sensor, the failure determination unit includes the engine An oil temperature estimation unit that estimates an oil temperature of the automatic transmission from the detection result of the engine temperature of the temperature detection means and obtains an estimated oil temperature, and a failure determination threshold value for determining that the oil temperature sensor has failed. A failure determination threshold value determination unit for determining, and a failure index determination unit for determining a failure index that increases as the oil temperature difference between the estimated oil temperature obtained by the oil temperature estimation unit and the detected oil temperature of the oil temperature sensor increases. , On time Total counts is a multiple of the failure index is required and judging with the oil temperature sensor by reaching the failure determination threshold value has failed for each.

この発明の油温センサの故障判定装置は、車両の状況に応じた油温センサの故障判定を早期に行えるとともに、誤判定を軽減可能とする。 The oil temperature sensor failure determination device according to the present invention can perform failure determination of the oil temperature sensor in accordance with vehicle conditions at an early stage and can reduce erroneous determination.

図１は油温センサの故障判定装置の入出力信号を説明するブロック図である。（実施例）FIG. 1 is a block diagram illustrating input / output signals of a failure determination device for an oil temperature sensor. (Example) 図２は油温センサの故障判定のフローチャートである。（実施例）FIG. 2 is a flowchart for determining the failure of the oil temperature sensor. (Example) 図３は所定のエンジン水温における故障指数（異常度、正常度）を示す図である。（実施例）FIG. 3 is a diagram showing a failure index (abnormality, normality) at a predetermined engine water temperature. (Example) 図４は油温差とカウント数と精度との関係を示す図である。（実施例）FIG. 4 is a diagram showing the relationship between the oil temperature difference, the count number, and the accuracy. (Example) 図５はエンジンの始動後に油温センサの出力値が途中から固着した場合の故障診断状況を説明するタイムチャートである。（実施例）FIG. 5 is a time chart for explaining a failure diagnosis situation when the output value of the oil temperature sensor is fixed midway after the engine is started. (Example) 図６はエンジンの始動直後から油温センサの出力値が高い状態に固着した場合の故障診断状況を説明するタイムチャートである。（実施例）FIG. 6 is a time chart for explaining a failure diagnosis situation when the output value of the oil temperature sensor is fixed in a high state immediately after the engine is started. (Example)

この発明は、その車両の状況に応じた油温センサの故障判定を早期に行えるとともに、誤判定を軽減可能とする目的を、常に変化する車両の状況を考慮して実現するものである。 The present invention realizes the object of making it possible to determine the failure of the oil temperature sensor in accordance with the situation of the vehicle at an early stage and to reduce the erroneous judgment in consideration of the constantly changing situation of the vehicle.

図１〜図６は、この発明の実施例を示すものである。
図１において、１は車両に搭載されて動力源となるエンジン、２はこのエンジン１に連結してエンジン１の出力を車両の駆動輪に伝える自動変速機である。
このエンジン１は、制御手段（ＥＣＭ）３によって制御される。
この制御手段３は、図１に示すように、油温センサの故障判定装置４に用いられる。
この故障判定装置４において、制御手段３には、入力側で、自動変速機２のシフトポジションを検出するシフトスイッチ５と、車両の速度を検出する車速センサ６と、Ｏ／Ｄオフスイッチ７と、自動変速機２の油温（Ｔｏ０）を検出する油温センサ８と、自動変速機２の入力軸回転センサ９と、ストップランプスイッチ１０と、スロットル開度を検出するスロットルセンサ１１と、エンジン１の温度として冷却水温度をエンジン水温（Ｔｅ）として検出するエンジン温度検出手段である水温センサ１２と、エンジン回転数を検出するエンジン回転数センサ１３と、イグニションスイッチ（ＩＧ・ＳＷ）１４とが連絡し、また、出力側では、自動変速機２のシフトソレノイド１５と、自動変速機２のライン圧制御ソレノイド１６と、自動変速機２のロックアップソレノイド１７と、チェックエンジンランプ１８と、Ｏ／Ｄオフランプ１９とが連絡している。
また、制御手段３は、変速制御部２０と、ロックアップ制御部２１と、スリップ制御部２２と、ライン圧制御部２３と、Ｏ／Ｄ禁止制御部２４と、故障判定部２５と、フェイルセーフ機能部２６と、ウォーニング機能部２７とを備えている。 1 to 6 show an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes an engine that is mounted on a vehicle and serves as a power source. Reference numeral 2 denotes an automatic transmission that is connected to the engine 1 and transmits the output of the engine 1 to driving wheels of the vehicle.
The engine 1 is controlled by a control means (ECM) 3.
As shown in FIG. 1, the control means 3 is used in a failure determination device 4 for an oil temperature sensor.
In this failure determination device 4, the control means 3 includes, on the input side, a shift switch 5 that detects the shift position of the automatic transmission 2, a vehicle speed sensor 6 that detects the vehicle speed, and an O / D off switch 7. , An oil temperature sensor 8 for detecting the oil temperature (To0) of the automatic transmission 2, an input shaft rotation sensor 9 for the automatic transmission 2, a stop lamp switch 10, a throttle sensor 11 for detecting the throttle opening, and an engine A water temperature sensor 12 that is an engine temperature detecting means for detecting the coolant temperature as the engine water temperature (Te) as a temperature of 1, an engine speed sensor 13 for detecting the engine speed, and an ignition switch (IG · SW) 14. Further, on the output side, the shift solenoid 15 of the automatic transmission 2, the line pressure control solenoid 16 of the automatic transmission 2, and the automatic transmission And of the lock-up solenoid 17, and the check engine lamp 18, and the O / D off the lamp 19 is in communication.
The control means 3 includes a shift control unit 20, a lockup control unit 21, a slip control unit 22, a line pressure control unit 23, an O / D prohibition control unit 24, a failure determination unit 25, a fail safe, A function unit 26 and a warning function unit 27 are provided.

図３〜図６に示すように、この実施例に係る故障判定装置４では、正常な油温センサ８を用いて、事前にその油温センサ８が検出した油温（Ｔｏ０）（図面上では「油温Ｔｏ０」と記す）をその油温（Ｔｏ０）の検出精度と共にマップデータ化し、さらに、その検出精度に基づいて、故障指数（異常度（Ｃｕ）、正常度（Ｃｄ））を設定したマップデータを油温センサ８の故障判定に用いる。
また、車両の走行状態のパラメータとしてのエンジン水温（Ｔｅ）を基に、自動変速機２の推定油温（Ｔｘ）を求め、併せて、第一所定値（Ｔｏ１）（図面上では「油温閾値Ｔｏ１」と記す）〜第四所定値（Ｔｏ４）（図面上では「油温閾値Ｔｏ４」と記す）を求め、油温センサ８の検出油温（Ｔｏ０）が上記の各所定値で区画され、どの温度領域にあるかを判定し、推定油温（Ｔｘ）と、その時の油温センサ８が検出した油温（Ｔｏ０）との油温差（ΔＴ）に応じて、マップデータより異常度（Ｃｕ）、正常度（Ｃｄ）を求める。
そして、この求めた異常度（Ｃｕ）、正常度（Ｃｄ）をカウント数（Ｃｏ）にて加算、減算して行き、カウント数（Ｃｏ）が故障判定閾値（Ｃ１）に達することで、油温センサ８の故障を判断し、一方、カウント数（Ｃｏ）が正常判定閾値（Ｃ２）に達することで、油温センサ８の正常を判断する。
そして、故障判定部２５では、エンジン水温（Ｔｅ）から自動変速機２の油温を推定して推定油温（Ｔｘ）を求め、エンジン水温（Ｔｅ）と自動変速機２の検出された油温（Ｔｏ０）から油温センサ８の故障の度合いを示す故障指数（異常度（Ｃｕ）、正常度（Ｃｄ））を求め、この故障指数（異常度（Ｃｕ）、正常度（Ｃｄ））を求めるためにエンジン水温（Ｔｅ）から各油温閾値としての第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）を設定し、そして、故障指数（異常度（Ｃｕ）、正常度（Ｃｄ））を合計してその値をカウントする。
即ち、この実施例において、車両の走行状態のパラメータからカウント数（Ｃｏ）の故障判定閾値（Ｃ１）、正常判定閾値（Ｃ２）と各油温閾値としての第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）を設定し、油温センサ８の検出油温（Ｔｏ０）と比較することで、走行状態に応じた油温センサ８の故障診断を行うものである。これにより、車両の状況に応じた油温センサ８の故障診断を行うことができ、故障検出の精度を上げ、診断時間の短縮を可能とする。
そして、故障判定部２５によって油温センサ８の故障が判定された場合、制御手段３は、乗員に油温センサ８の故障を知らせるウォーニング機能により、チェックエンジンランプ１８の点灯の実施を行うとともに、必要最低限の自動変速機２の変速制御を行えるよう、フェイルセーフ制御を実施する。 As shown in FIGS. 3 to 6, in the failure determination device 4 according to this embodiment, a normal oil temperature sensor 8 is used, and an oil temperature (To0) (To0) detected by the oil temperature sensor 8 in advance (in the drawing). “Oil temperature To0”) is converted into map data together with the detection accuracy of the oil temperature (To0), and the failure index (abnormality (Cu), normality (Cd)) is set based on the detection accuracy. The map data is used for determining the failure of the oil temperature sensor 8.
Further, the estimated oil temperature (Tx) of the automatic transmission 2 is obtained on the basis of the engine water temperature (Te) as a parameter of the running state of the vehicle, and a first predetermined value (To1) (in the drawing, “oil temperature” The threshold value To1 ”to the fourth predetermined value (To4) (denoted as“ oil temperature threshold value To4 ”in the drawing) are obtained, and the detected oil temperature (To0) of the oil temperature sensor 8 is divided by the predetermined values. In accordance with the oil temperature difference (ΔT) between the estimated oil temperature (Tx) and the oil temperature (To0) detected by the oil temperature sensor 8 at that time, an abnormality degree (ΔT) is determined from the map data. Cu) and normality (Cd) are obtained.
Then, the obtained abnormality degree (Cu) and normality (Cd) are added and subtracted by the count number (Co), and the count number (Co) reaches the failure determination threshold value (C1). The failure of the sensor 8 is determined. On the other hand, when the count number (Co) reaches the normal determination threshold value (C2), the normality of the oil temperature sensor 8 is determined.
Then, the failure determination unit 25 estimates the oil temperature of the automatic transmission 2 from the engine water temperature (Te) to obtain the estimated oil temperature (Tx), and the engine water temperature (Te) and the detected oil temperature of the automatic transmission 2. A failure index (abnormality (Cu), normality (Cd)) indicating the degree of failure of the oil temperature sensor 8 is obtained from (To0), and this failure index (abnormality (Cu), normality (Cd)) is obtained. Therefore, the first predetermined value (To1) to the fourth predetermined value (To4) as each oil temperature threshold value are set from the engine water temperature (Te), and the failure index (abnormality (Cu), normality (Cd)) Are counted and the value is counted.
That is, in this embodiment, the failure determination threshold value (C1), the normality determination threshold value (C2) of the count number (Co), and the first predetermined value (To1) to the fourth oil temperature threshold value are determined from the parameters of the running state of the vehicle. By setting a predetermined value (To4) and comparing it with the detected oil temperature (To0) of the oil temperature sensor 8, a failure diagnosis of the oil temperature sensor 8 according to the running state is performed. As a result, failure diagnosis of the oil temperature sensor 8 according to the vehicle condition can be performed, the failure detection accuracy can be increased, and the diagnosis time can be shortened.
When the failure determination unit 25 determines that the oil temperature sensor 8 has failed, the control unit 3 turns on the check engine lamp 18 with a warning function that notifies the occupant of the failure of the oil temperature sensor 8. Fail safe control is performed so that the minimum required shift control of the automatic transmission 2 can be performed.

このため、故障判定部２５は、図１に示すように、水温センサ１２のエンジン水温（Ｔｅ）の検出結果から自動変速機２の油温を推定して推定油温（Ｔｘ）を求める油温推定部２５Ａと、油温センサ８が故障していると判定するための故障判定閾値（Ｃ１）（図５、図６参照）を決定する故障判定閾値決定部２５Ｂと、油温推定部２５Ａが求めた推定油温（Ｔｘ）と油温センサ８の検出油温（Ｔｏ０）との油温差（ΔＴ）が大きいほど大となる故障指数（異常度Ｃｕ、正常度Ｃｄ）を求める故障指数決定部２５Ｃと、故障指数（異常度Ｃｕ、正常度Ｃｄ）をカウントする故障指数カウント部２５Ｄとを備え、所定時間毎に求められる複数の前記故障指数の合計であるカウント数（Ｃｏ）が前記故障判定閾値（Ｃ１）に達することで油温センサ８が故障していると判定する。
これにより、エンジン水温（Ｔｅ）から求める推定油温（Ｔｘ）と油温センサ８の検出油温（Ｔｏ０）との油温差（ΔＴ）が大きいほど、早期に油温センサ８の故障判定できる。 Therefore, as shown in FIG. 1, the failure determination unit 25 estimates the oil temperature of the automatic transmission 2 from the detection result of the engine water temperature (Te) of the water temperature sensor 12 and obtains the estimated oil temperature (Tx). An estimation unit 25A, a failure determination threshold value determination unit 25B that determines a failure determination threshold value (C1) (see FIGS. 5 and 6) for determining that the oil temperature sensor 8 has failed, and an oil temperature estimation unit 25A Failure index determination unit for determining a failure index (abnormality Cu, normality Cd) that increases as the oil temperature difference (ΔT) between the obtained estimated oil temperature (Tx) and the detected oil temperature (To0) of the oil temperature sensor 8 increases. 25C and a failure index counting unit 25D that counts a failure index (abnormality Cu, normality Cd), and a count number (Co) that is a sum of a plurality of the failure indexes obtained every predetermined time is the failure determination Oil temperature sensor by reaching the threshold (C1) There is judged to be a failure.
Thereby, the failure of the oil temperature sensor 8 can be determined earlier as the oil temperature difference (ΔT) between the estimated oil temperature (Tx) obtained from the engine water temperature (Te) and the detected oil temperature (To0) of the oil temperature sensor 8 is larger.

また、故障判定部２５は、前記故障指数を求めるための基準となる第一所定値（Ｔｏ１）と、この第一所定値（Ｔｏ１）よりも小さい第二所定値（Ｔｏ２）と、検出油温（Ｔｏ０）が第一所定値（Ｔｏ１）よりも大きい温度領域若しくは第二所定値（Ｔｏ２）よりも小さい温度領域である第一領域を設定し（図４参照）、検出油温（Ｔｏ０）が第一領域内にある場合に、前記故障指数はカウント数（Ｃｏ）を故障判定閾値（Ｃ１）側に近づける値を採る（図３参照）。
故障判定部２５は、図５、図６に示すように、第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）を設定する油温閾値決定部２５Ｅを備える。
これにより、油温センサ８が故障していると推測される温度領域である第一領域が第一所定値（Ｔｏ１）及び第二所定値（Ｔｏ２）によって明確化され、油温センサ８の故障判定精度を向上させることができる。 Further, the failure determination unit 25 uses a first predetermined value (To1) as a reference for obtaining the failure index, a second predetermined value (To2) smaller than the first predetermined value (To1), and the detected oil temperature. A first region where (To0) is a temperature region larger than the first predetermined value (To1) or a temperature region smaller than the second predetermined value (To2) is set (see FIG. 4), and the detected oil temperature (To0) is set. When in the first area, the failure index takes a value that brings the count number (Co) closer to the failure determination threshold (C1) side (see FIG. 3).
The failure determination unit 25 includes an oil temperature threshold value determination unit 25E that sets a first predetermined value (To1) to a fourth predetermined value (To4) as shown in FIGS.
As a result, the first region, which is a temperature region in which it is estimated that the oil temperature sensor 8 has failed, is clarified by the first predetermined value (To1) and the second predetermined value (To2). The determination accuracy can be improved.

更に、故障判定部２５は、油温センサ８が正常に機能していると判定する正常判定閾値（Ｃ２）を決定する正常判定閾値決定部２５Ｆと、カウント数（Ｃｏ）を故障判定閾値（Ｃ１）より遠ざけるよう加算される正常指数を求める正常指数決定部２５Ｇとを備え、前記正常指数を求めるための基準となる第三所定値（Ｔｏ３）とこの第三所定値（Ｔｏ３）よりも小さい第四所定値（Ｔｏ４）と、検出油温（Ｔｏ０）が第三所定値（Ｔｏ３）よりも小さく且つ前記第四所定値（Ｔｏ４）よりも大きい温度領域である第二領域を設定し（図４参照）、検出油温（Ｔｏ０）が前記第二領域内にある場合に、油温差（ΔＴ）が小さいほど、カウント数（Ｃｏ）を故障判定閾値（Ｃ１）より遠ざけるとともに正常判定閾値（Ｃ２）に近づける。
これにより、エンジン水温（Ｔｅ）から求める推定油温（Ｔｘ）と油温センサ８の検出油温（Ｔｏ０）との油温差（ΔＴ）が小さいほど、早期に油温センサ８が正常に機能していると判定できる。また、油温センサ８が正常に機能していると予想される温度領域である第二領域が第三所定値（Ｔｏ３）及び第四所定値（Ｔｏ４）によって明確化され、油温センサ８の故障判定精度及び正常判定精度を向上させることができる。 Further, the failure determination unit 25 includes a normal determination threshold value determination unit 25F that determines a normal determination threshold value (C2) for determining that the oil temperature sensor 8 is functioning normally, and sets the count number (Co) as a failure determination threshold value (C1). And a normal index determining unit 25G for determining a normal index that is added so as to be further away, and a third predetermined value (To3) serving as a reference for determining the normal index and a value smaller than the third predetermined value (To3) Four predetermined values (To4) and a second region that is a temperature region in which the detected oil temperature (To0) is smaller than the third predetermined value (To3) and larger than the fourth predetermined value (To4) are set (FIG. 4). Reference), when the detected oil temperature (To0) is within the second region, the smaller the oil temperature difference (ΔT), the farther the count number (Co) is from the failure determination threshold (C1) and the normal determination threshold (C2). Move closer to.
Thereby, the oil temperature sensor 8 functions normally earlier as the oil temperature difference (ΔT) between the estimated oil temperature (Tx) obtained from the engine water temperature (Te) and the detected oil temperature (To0) of the oil temperature sensor 8 is smaller. Can be determined. Further, the second region, which is a temperature region where the oil temperature sensor 8 is expected to function normally, is clarified by the third predetermined value (To3) and the fourth predetermined value (To4). Failure determination accuracy and normality determination accuracy can be improved.

更にまた、故障判定部２５は、エンジン水温（Ｔｅ）が高くなるほど、故障判定閾値（Ｃ１）と正常判定閾値（Ｃ２）との差を小さく設定し、第一所定値（Ｔｏ１）と第二所定値（Ｔｏ２）との差を小さく設定し、第三所定値（Ｔｏ３）と第四所定値（Ｔｏ４）との差を小さく設定する。
これは、車両が走行することで、エンジン水温（Ｔｅ）、自動変速機２の検出油温（Ｔｏ０）が上昇し、エンジン水温（Ｔｅ）、自動変速機２の検出油温（Ｔｏ０）が車両の外的要因（外気温等）の影響を受け難くなり、自動変速機２の推定油温（Ｔｘ）がエンジン水温（Ｔｅ）から推定しやすいことによる。つまり、推定油温（Ｔｘ）の推定精度が向上する。そのため、故障指数を求めるための第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）の各所定値の温度差を小さくでき、第一領域を拡大して、第二領域、第三領域を縮小して油温センサ８の故障判定条件を厳しくできる。また、推定油温（Ｔｘ）の推定精度が向上していることで、故障判定閾値（Ｃ１）と正常判定閾値（Ｃ２）との差を小さく設定して、油温センサ８の故障判定までに要する時間を減らすことができる。これにより、早期に油温センサ８の故障判定や正常判定を可能としている。 Furthermore, the failure determination unit 25 sets the difference between the failure determination threshold value (C1) and the normal determination threshold value (C2) to be smaller as the engine coolant temperature (Te) becomes higher, and the first predetermined value (To1) and the second predetermined value. The difference from the value (To2) is set small, and the difference between the third predetermined value (To3) and the fourth predetermined value (To4) is set small.
This is because when the vehicle travels, the engine water temperature (Te) and the detected oil temperature (To0) of the automatic transmission 2 rise, and the engine water temperature (Te) and the detected oil temperature (To0) of the automatic transmission 2 increase. This is because the estimated oil temperature (Tx) of the automatic transmission 2 is easily estimated from the engine water temperature (Te). That is, the estimation accuracy of the estimated oil temperature (Tx) is improved. Therefore, the temperature difference of each predetermined value of the first predetermined value (To1) to the fourth predetermined value (To4) for obtaining the failure index can be reduced, the first region is expanded, and the second region and the third region are expanded. The condition for failure determination of the oil temperature sensor 8 can be tightened by reducing the size. Further, since the estimation accuracy of the estimated oil temperature (Tx) is improved, the difference between the failure determination threshold value (C1) and the normality determination threshold value (C2) is set small, and the failure determination of the oil temperature sensor 8 is performed. The time required can be reduced. As a result, failure determination and normality determination of the oil temperature sensor 8 are possible at an early stage.

また、故障判定部２５は、第一所定値（Ｔｏ１）と第三所定値（Ｔｏ３）では第一所定値（Ｔｏ１）が大きく、且つ第二所定値（Ｔｏ２）と第四所定値（Ｔｏ４）では第二所定値（Ｔｏ２）が小さい大小関係を持ち、検出油温（Ｔｏ０）が第一所定値（Ｔｏ１）よりも小さく第三所定値（Ｔｏ３）よりも大きい、若しくは検出油温（Ｔｏ０）が第二所定値（Ｔｏ２）よりも大きく第四所定値（Ｔｏ４）よりも小さい温度領域である第三領域を設定し、検出油温（Ｔｏ０）が第三領域内にある場合に、カウント数（Ｃｏ）に加算する値は故障指数及び正常指数が共に零（０）である。
これにより、エンジン水温（Ｔｅ）より推定される推定油温（Ｔｘ）と油温センサ８の検出油温（Ｔｏ０）との油温差（ΔＴ）が大きいものの、正常に機能している油温センサ８が検出し得る検出油温（Ｔｏ０）であって、油温センサ８が故障しているか否かの判断がつかない場合、その検出油温（Ｔｏ０）に基づく結果を油温センサ８の故障判定に用いないことで、誤った油温センサ８の故障判定を防止できる。 Further, the failure determination unit 25 has a first predetermined value (To1) that is larger than the first predetermined value (To1) and the third predetermined value (To3), and a second predetermined value (To2) and a fourth predetermined value (To4). The second predetermined value (To2) has a small and large relationship, and the detected oil temperature (To0) is smaller than the first predetermined value (To1) and larger than the third predetermined value (To3), or the detected oil temperature (To0). Is set to a third region that is a temperature region that is larger than the second predetermined value (To2) and smaller than the fourth predetermined value (To4), and the detected oil temperature (To0) is within the third region. The value added to (Co) is zero (0) for both the failure index and the normality index.
Thereby, although the oil temperature difference (ΔT) between the estimated oil temperature (Tx) estimated from the engine water temperature (Te) and the detected oil temperature (To0) of the oil temperature sensor 8 is large, the oil temperature sensor functioning normally. 8 is a detected oil temperature (To0) that can be detected, and if it is not possible to determine whether or not the oil temperature sensor 8 is out of order, the result based on the detected oil temperature (To0) By not using the determination, it is possible to prevent erroneous determination of the oil temperature sensor 8.

更に、故障判定部２５は、カウント数（Ｃｏ）に設定する初期値（Ｃｉ）として、油温センサ８の故障判定処理開始時において、故障判定閾値（Ｃ１）と正常判定閾値（Ｃ２）との中間の値を採る。
これにより、カウント数（Ｃｏ）が故障判定閾値（Ｃ１）若しくは正常判定閾値（Ｃ２）に達するまでの時間を大きく要することを避けられ、早期に油温センサ８の故障判定や正常判定を行うことができる。 Further, the failure determination unit 25 uses the failure determination threshold value (C1) and the normal determination threshold value (C2) as the initial value (Ci) to be set for the count number (Co) when the failure determination process of the oil temperature sensor 8 is started. Take an intermediate value.
As a result, it is possible to avoid taking a long time until the count number (Co) reaches the failure determination threshold value (C1) or the normality determination threshold value (C2), and to perform failure determination or normal determination of the oil temperature sensor 8 at an early stage. Can do.

次いで、この実施例に係る油温センサ８の故障判定について、図２のフローチャートに基づいて説明する。
この故障判定においては、油温センサ８が検出する油温（Ｔｏ０）と、その油温（Ｔｏ０）を自動変速機２の油温を推定するための車両のパラメータ（例えば、エンジン水温）を用いて自動変速機２の油温を推定して推定油温（Ｔｘ）を求め、それらの油温差（ΔＴ）に応じて、油温センサ８が故障していると判断するためのカウント数（Ｃｏ）に加算若しくは減算する故障指数を求め、その求めた故障指数に加算若しくは減算の値を加えて行き、ある所定値（油温閾値）に達することで、油温センサ８が故障しているか否かを判定する。
図２に示すように、イグニッションスイッチ１４のＯＮがトリガとなり（ステップＡ０１）、エンジン１が始動すると（ステップＡ０２）、制御手段３のプログラムが実行され、カウント数（Ｃｏ）に初期値（Ｃｉ）を代入する（ステップＡ０３）。ここで、カウント数（Ｃｏ）とは、油温センサ８が故障しているか否かを判断する指標である。また、このプログラムでは、故障判定閾値（Ｃ１）と正常判定閾値（Ｃ２）を備える。
そして、カウント数（Ｃｏ）が故障判定閾値（Ｃ１）に達することで、油温センサ８が故障していると判定し、正常判定閾値（Ｃ２）に達する場合は、正常に機能していると判定する。なお、初期値（Ｃｉ）は、故障判定閾値（Ｃ１）と正常判定閾値（Ｃ２）との中間の値を採る。また、故障判定閾値（Ｃ１）＞正常判定閾値（Ｃ２）の大小関係を持つ。
油温センサ８が故障しているおそれがあると判定された場合は、故障判定閾値（Ｃ１）に近づくようにカウント数（Ｃｏ）の値が大となり、油温センサ８が正常に機能していると予測される場合には、正常判定閾値（Ｃ２）に近づくようにカウント数（Ｃｏ）の値が小となる。
なお、エンジン水温（Ｔｅ）が比較的高温である場合は、初期値（Ｃｉ）を正常判定閾値（Ｃ２）に近づけるように小さく設定しても良い。これにより、エンジン水温（Ｔｅ）が比較的高温である場合には、油温センサ８が正常に機能していると早期に判断することができる。エンジン水温（Ｔｅ）が高い場合には、自動変速機２の油温（Ｔｏ０）も高い場合が多く、自動変速機２の油温（Ｔｏ０）が低温時に比べて比較的予想しやすいためである。 Next, failure determination of the oil temperature sensor 8 according to this embodiment will be described based on the flowchart of FIG.
In this failure determination, the oil temperature (To0) detected by the oil temperature sensor 8 and vehicle parameters (for example, engine water temperature) for estimating the oil temperature of the automatic transmission 2 are used based on the oil temperature (To0). The estimated oil temperature (Tx) is obtained by estimating the oil temperature of the automatic transmission 2, and the count number (Co) for determining that the oil temperature sensor 8 has failed according to the oil temperature difference (ΔT). ) Is added to or subtracted from the failure index, and the added or subtracted value is added to the determined failure index to reach a predetermined value (oil temperature threshold value). Determine whether.
As shown in FIG. 2, when the ignition switch 14 is turned on (step A01) and the engine 1 is started (step A02), the program of the control means 3 is executed, and the count value (Co) is set to the initial value (Ci). Is substituted (step A03). Here, the count number (Co) is an index for determining whether or not the oil temperature sensor 8 has failed. In addition, this program includes a failure determination threshold value (C1) and a normality determination threshold value (C2).
Then, when the count number (Co) reaches the failure determination threshold (C1), it is determined that the oil temperature sensor 8 has failed, and when it reaches the normal determination threshold (C2), it is functioning normally. judge. The initial value (Ci) takes an intermediate value between the failure determination threshold (C1) and the normal determination threshold (C2). Further, there is a magnitude relationship of failure determination threshold (C1)> normal determination threshold (C2).
When it is determined that the oil temperature sensor 8 may be broken, the count value (Co) increases so as to approach the failure determination threshold (C1), and the oil temperature sensor 8 functions normally. When it is predicted that the count number (Co) approaches the normal determination threshold value (C2), the count number (Co) decreases.
When the engine water temperature (Te) is relatively high, the initial value (Ci) may be set small so as to approach the normal determination threshold value (C2). Thereby, when the engine water temperature (Te) is relatively high, it can be determined early that the oil temperature sensor 8 is functioning normally. This is because when the engine water temperature (Te) is high, the oil temperature (To0) of the automatic transmission 2 is often high, and the oil temperature (To0) of the automatic transmission 2 is relatively predictable compared to when the temperature is low. .

そして、エンジン１の始動から所定期間経た所定の時間（ｔｗ）を経過したか否かを判断する（ステップＡ０４）（図５、図６参照）。このステップＡ０４がＮＯの場合には、この判断を所定の時間（ｔｗ）が経過するまで継続する。
このステップＡ０４を設けた理由は、フロー処理の開始直後では油温センサ８から検出される油温（Ｔｏ０）が大きく変動する場合があるためである。つまり、自動変速機２の油温センサ８の故障判定を行うにあたり、エンジン水温（Ｔｅ）を基に自動変速機２の油温（Ｔｏ０）を推定して推定油温（Ｔｘ）を求め、この推定油温（Ｔｘ）と油温センサ８の検出した油温（Ｔｏ０）との比較を行うが、例えば、事前に車両が走行しており、エンジン１が比較的高温となっているような場合は、エンジン１内の高温な冷却水とラジエータ内の低温な冷却水とが混ざり合い、冷却水の温度が安定せず、このような状況の下での油温センサ８の故障診断は結果の信頼性が低く、誤判定を招くおそれがあることから、このような故障診断結果を除くためである。
その後、車両のパラメータとしての水温センサ１２からのエンジン水温（Ｔｅ）と油温センサ８からの検出油温（Ｔｏ０）とを取得し（ステップＡ０５）、そして、エンジン水温（Ｔｅ）から、自動変速機２の推定油温（Ｔｘ）、第一所定値（油温閾値Ｔｏ１）、第二所定値（油温閾値Ｔｏ２）、第三所定値（油温閾値Ｔｏ３）、第四所定値（油温閾値Ｔｏ４）、油温センサ８が故障していると判定する故障判定閾値（Ｃ１）、油温センサ８が正常に作動していることを判定する正常判定閾値（Ｃ２）を求める（ステップＡ０６）。
これら推定油温（Ｔｘ）及び第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）は、事前に用意したマップデータより求める。このマップデータは、正常に機能している油温センサ８等を用いて測定した、エンジン水温（Ｔｅ）と自動変速機２の推定油温（Ｔｘ）との関係を示したマップデータである。
なお、図４〜図６に示すように、第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）は、カウント数（Ｃｏ）に加算する異常度（Ｃｕ）若しくは減算する正常度（Ｃｄ）を求めるためにあり、その大小関係が、Ｔｏ１≧Ｔｏ３＞Ｔｏ４≧Ｔｏ２にある。また、Ｔｏ０≧Ｔｏ１若しくはＴｏ０≦Ｔｏ２となる領域を第一領域とし、Ｔｏ１及びＴｏ２を第一所定値とし、また、Ｔｏ３＜Ｔｏ０＜Ｔｏ４となる領域を第二領域とし、Ｔｏ３及びＴｏ４を第二所定値とし、さらに、Ｔｏ３≦Ｔｏ０＜Ｔｏ１若しくはＴｏ４≦Ｔｏ０＜Ｔｏ２となる領域を第三領域とする。 Then, it is determined whether or not a predetermined time (tw) after a predetermined period has elapsed since the start of the engine 1 (step A04) (see FIGS. 5 and 6). If step A04 is NO, this determination is continued until a predetermined time (tw) has elapsed.
The reason for providing this step A04 is that the oil temperature (To0) detected from the oil temperature sensor 8 may fluctuate greatly immediately after the start of the flow process. That is, when performing the failure determination of the oil temperature sensor 8 of the automatic transmission 2, the estimated oil temperature (Tx) is obtained by estimating the oil temperature (To0) of the automatic transmission 2 based on the engine water temperature (Te). The estimated oil temperature (Tx) is compared with the oil temperature (To0) detected by the oil temperature sensor 8, for example, when the vehicle is running in advance and the engine 1 is at a relatively high temperature. The high temperature cooling water in the engine 1 and the low temperature cooling water in the radiator are mixed, and the temperature of the cooling water is not stable. This is because such a failure diagnosis result is excluded because the reliability is low and an erroneous determination may be caused.
Thereafter, the engine water temperature (Te) from the water temperature sensor 12 and the detected oil temperature (To0) from the oil temperature sensor 8 as vehicle parameters are acquired (step A05), and automatic transmission is performed from the engine water temperature (Te). Estimated oil temperature (Tx), first predetermined value (oil temperature threshold To1), second predetermined value (oil temperature threshold To2), third predetermined value (oil temperature threshold To3), fourth predetermined value (oil temperature) Threshold value To4), a failure determination threshold value (C1) for determining that the oil temperature sensor 8 has failed, and a normality determination threshold value (C2) for determining that the oil temperature sensor 8 is operating normally (step A06). .
The estimated oil temperature (Tx) and the first predetermined value (To1) to the fourth predetermined value (To4) are obtained from map data prepared in advance. This map data is map data showing the relationship between the engine water temperature (Te) and the estimated oil temperature (Tx) of the automatic transmission 2 measured using the normally functioning oil temperature sensor 8 or the like.
As shown in FIGS. 4 to 6, the first predetermined value (To1) to the fourth predetermined value (To4) are the degree of abnormality (Cu) to be added to the count number (Co) or the degree of normality (Cd) to be subtracted. The magnitude relationship is To1 ≧ To3> To4 ≧ To2. In addition, a region where To0 ≧ To1 or To0 ≦ To2 is set as the first region, To1 and To2 are set as the first predetermined value, a region where To3 <To0 <To4 is set as the second region, and To3 and To4 are set as the second region. A predetermined value is set, and a region where To3 ≦ To0 <To1 or To4 ≦ To0 <To2 is set as a third region.

そして、検出油温（Ｔｏ０）と推定油温（Ｔｘ）との油温差（ΔＴ）を、
ΔＴ＝Ｔｘ−Ｔｏ０
で求める（ステップＡ０７）。
そして、Ｔｏ０≧Ｔｏ１又はＴｏ０≦Ｔｏ２か否か、つまり、検出油温（Ｔｏ０）が第一領域内にあるか否かを判断する（ステップＡ０８）。
このステップＡ０８がＹＥＳの場合には、検出油温（Ｔｏ０）が第一領域内にあると判定中であって、油温センサ８が故障しているおそれがあるとし、図３、図４のマップデータから異常度（Ｃｕ）を求め（ステップＡ０９）、この異常度（Ｃｕ）をカウント数（Ｃｏ）に加算する（ステップＡ１０）。このとき、Ｃｏ≧Ｃｍａｘであれば、カウント数（Ｃｏ）は、最大故障カウント数（Ｃｍａｘ）とする。
図３、図４のマップデータは、カウント数（Ｃｏ）に加算する異常度（Ｃｕ）若しくは減算する正常度（Ｃｄ）を求めるためのものである。この図３、図４のマップデータは、自動変速機２の推定油温（Ｔｘ）と油温センサ８の検出油温（Ｔｏ０）との油温差（ΔＴ）がその時の精度と、精度に応じた異常度（Ｃｕ）、正常度（Ｃｄ）との関係を示したものとなっている。ここで、精度とは、所定のエンジン水温（Ｔｅ）における油温差（ΔＴ）の発生度合いの高さを示す値である。この図３、図４のマップデータを例にとると、この精度は、１００回測定した場合の検出し得る回数を示している。例えば、油温差（ΔＴ）が零（０℃）となるのは、１００回測定した場合に、４７回取り得る可能性があること示している。油温差（ΔＴ）が小さいほど正常度（Ｃｄ）が大となる一方、油温差（ΔＴ）が大きいほど異常度（Ｃｕ）が大となる。検出油温（Ｔｏ０）が推定油温（Ｔｘ）より離れるほど、油温センサ８が故障しているおそれが高いと考えられるためである。この精度の値に応じて、異常度（Ｃｕ）、正常度（Ｃｄ）が設定されている。
また、この図３、図４のマップデータは、あるエンジン水温（Ｔｅ）におけるデータを示す。実際は、エンジン水温（Ｔｅ）を複数の温度範囲（例えば、１０℃ごと）に分け、その夫々の温度範囲における図３、図４のマップデータを複数用意して、異常度（Ｃｕ）、正常度（Ｃｄ）を求める構成とする。
一方、前記ステップＡ０８がＮＯの場合には、Ｔｏ０≧Ｔｏ３又はＴｏ０≦Ｔｏ４か否か、つまり、検出油温（Ｔｏ０）が第二領域又は第三領域にあるか否かを判断する（ステップＡ１１）。 And the oil temperature difference (ΔT) between the detected oil temperature (To0) and the estimated oil temperature (Tx) is
ΔT = Tx−To0
(Step A07).
Then, it is determined whether or not To0 ≧ To1 or To0 ≦ To2, that is, whether or not the detected oil temperature (To0) is within the first region (step A08).
If this step A08 is YES, it is determined that the detected oil temperature (To0) is in the first region and the oil temperature sensor 8 may be broken, The degree of abnormality (Cu) is obtained from the map data (step A09), and this degree of abnormality (Cu) is added to the count number (Co) (step A10). At this time, if Co ≧ Cmax, the count number (Co) is set to the maximum failure count number (Cmax).
The map data in FIG. 3 and FIG. 4 is for obtaining the degree of abnormality (Cu) to be added to the count number (Co) or the degree of normality (Cd) to be subtracted. The map data in FIGS. 3 and 4 indicate that the oil temperature difference (ΔT) between the estimated oil temperature (Tx) of the automatic transmission 2 and the detected oil temperature (To0) of the oil temperature sensor 8 depends on the accuracy and accuracy at that time. The relationship between the degree of abnormality (Cu) and the degree of normality (Cd) is shown. Here, the precision is a value indicating the level of occurrence of the oil temperature difference (ΔT) at a predetermined engine water temperature (Te). Taking the map data of FIG. 3 and FIG. 4 as an example, this accuracy indicates the number of times that detection is possible when measurement is performed 100 times. For example, the oil temperature difference (ΔT) becomes zero (0 ° C.) indicates that there is a possibility that the oil temperature difference can be taken 47 times when measured 100 times. The smaller the oil temperature difference (ΔT), the greater the normality (Cd), while the greater the oil temperature difference (ΔT), the greater the degree of abnormality (Cu). This is because the more likely the detected oil temperature (To0) is farther from the estimated oil temperature (Tx), the higher the risk that the oil temperature sensor 8 is malfunctioning. The degree of abnormality (Cu) and the degree of normality (Cd) are set according to the accuracy value.
The map data in FIGS. 3 and 4 shows data at a certain engine coolant temperature (Te). Actually, the engine water temperature (Te) is divided into a plurality of temperature ranges (for example, every 10 ° C.), and a plurality of map data of FIG. 3 and FIG. 4 in each temperature range are prepared. It is assumed that (Cd) is obtained.
On the other hand, when step A08 is NO, it is determined whether or not To0 ≧ To3 or To0 ≦ To4, that is, whether or not the detected oil temperature (To0) is in the second region or the third region (step A11). ).

このステップＡ１１がＮＯの場合には、検出油温（Ｔｏ０）が第三領域内にあると判定中であり、図３、図４のマップデータから異常度（Ｃｕ）又は正常度（Ｃｄ）を求め（ステップＡ１２）、そして、カウント数（Ｃｏ）に異常度（Ｃｕ）又は正常度（Ｃｄ）を加算する（ステップＡ１３）。但し、この場合の異常度（Ｃｕ）、正常度（Ｃｄ）は、零（０）である。
この第三領域は、油温センサ８が正常に機能しているか、故障しているかが明確に判別できない領域である。この領域は、１００回測定した場合に、１回程度検出される可能性があって、油温センサ８に異常が発生しているか判断ができない。そのため、図３、図４に示すように、この第三領域では、異常度（Ｃｕ）、正常度（Ｃｄ）も零（０）を設定している。また、エンジン水温（Ｔｅ）や自動変速機２の検出油温（Ｔｏ０）が変動しやすい状況下では、このような第三領域を設けることで、油温センサ８の誤判定を行わないようにしている。但し、エンジン水温（Ｔｅ）や自動変速機２の検出油温（Ｔｏ０）が比較的安定しているような場合（例えば、比較的高温であるような状況下のような場合）には、特に第三領域を設けなくても良い。
前記ステップＡ１１がＹＥＳの場合には、検出油温（Ｔｏ０）が第二領域内にあると判定中であり、図３、図４のマップデータから正常度（Ｃｄ）を求め（ステップＡ１４）、そして、カウント数（Ｃｏ）から正常度（Ｃｄ）を減算する（ステップＡ１５）。但し、この場合、Ｃｕ≦０のとき、カウント数（Ｃｏ）は、零（０）とする。 When step A11 is NO, it is determined that the detected oil temperature (To0) is within the third region, and the degree of abnormality (Cu) or degree of normality (Cd) is determined from the map data of FIGS. Determination (step A12), and the degree of abnormality (Cu) or normality (Cd) is added to the count number (Co) (step A13). However, the degree of abnormality (Cu) and the degree of normality (Cd) in this case are zero (0).
This third region is a region where it is not possible to clearly determine whether the oil temperature sensor 8 is functioning normally or has failed. This region may be detected about once when measured 100 times, and it cannot be determined whether an abnormality has occurred in the oil temperature sensor 8. Therefore, as shown in FIGS. 3 and 4, in this third region, the degree of abnormality (Cu) and the degree of normality (Cd) are also set to zero (0). In addition, in a situation where the engine water temperature (Te) and the detected oil temperature (To0) of the automatic transmission 2 are likely to fluctuate, such a third region is provided so that the oil temperature sensor 8 is not erroneously determined. ing. However, especially when the engine water temperature (Te) and the detected oil temperature (To0) of the automatic transmission 2 are relatively stable (for example, when the temperature is relatively high). The third region may not be provided.
When step A11 is YES, it is determined that the detected oil temperature (To0) is in the second region, and the normality (Cd) is obtained from the map data of FIGS. 3 and 4 (step A14). Then, the normality (Cd) is subtracted from the count number (Co) (step A15). However, in this case, when Cu ≦ 0, the count number (Co) is zero (0).

前記ステップＡ１０の処理後、前記ステップＡ１３の処理後、又は、前記ステップＡ１５の処理後は、カウント数（Ｃｏ）≧故障判定閾値（Ｃ１）か否かを判断する（ステップＡ１６）。
このステップＡ１６がＹＥＳの場合には、油温センサ８が故障していると判定し、油温センサ８の故障判定結果を記録、油温センサ８の故障発生の警告灯の点灯、油温センサ８の故障によるフェイルセーフ制御（例えば、油温センサ８の検出結果によらない必要最低限の自動変速機２の変速制御等）の実行等を実施する（ステップＡ１７）。 After the process of step A10, after the process of step A13, or after the process of step A15, it is determined whether or not count number (Co) ≧ failure determination threshold value (C1) (step A16).
If this step A16 is YES, it is determined that the oil temperature sensor 8 has failed, the failure determination result of the oil temperature sensor 8 is recorded, the warning light indicating that the oil temperature sensor 8 has failed, the oil temperature sensor The execution of fail-safe control due to failure 8 (for example, the minimum necessary shift control of the automatic transmission 2 that does not depend on the detection result of the oil temperature sensor 8) is executed (step A17).

前記ステップＡ１６がＮＯの場合には、カウント数（Ｃｏ）≦正常側閾値（Ｃ２）か否かを判断する（ステップＡ１８）。
このステップＡ１８がＹＥＳの場合には、油温センサ８は正常に機能していると判定したとする（ステップＡ１９）。
前記ステップＡ１７の処理後、前記ステップＡ１８がＮＯの場合、前記ステップＡ１９の処理後は、イグニッションスイッチ１４がオフがなされたか否かを判定する（ステップＡ２０）。これは、乗員の車両の使用意思を確認するためのものである。
このステップＡ２０がＹＥＳで、イグニッションスイッチ１４がオフとなれば、車両の使用意思がないと判断でき、プログラムをエンドとする（ステップＡ２１）。
しかし、このステップＡ２０がＮＯで、イグニッションスイッチ１４がオンであれば、前記ステップＡ０５に戻り、次のフロー処理の実行に移り、再度、カウント数（Ｃｏ）の結果から油温センサ８の故障若しくは正常の判定を行う。その場合、前回のカウント数（Ｃｏ）を引き継いで処理を続ける。
但し、前記ステップＡ１７若しくは前記ステップＡ１９を経由した場合、つまり、油温センサ８が故障若しくは正常と判断された場合には、前記ステップＡ０３からフロー処理を開始し、新たにカウント数（Ｃｏ）に初期値（Ｃｉ）を代入して処理を行うとしても良い。この場合は、前記ステップＡ０４を行わず、前記ステップＡ０５に進んでフロー処理を進める。
このフロー処理は、乗員の車両の運転意思が継続する間に行われる。具体的には、例えばイグニッションスイッチ１４がオンとなってからオフになるまでの間に実施される。そのため、エンジン１の自動停止（エンジンアイドルストップ等）による一時的なエンジン１の停止の間も、このフロー処理は継続して実行される。 If step A16 is NO, it is determined whether or not the count number (Co) ≦ normal threshold (C2) (step A18).
If this step A18 is YES, it is determined that the oil temperature sensor 8 is functioning normally (step A19).
After step A17, if step A18 is NO, after step A19, it is determined whether or not the ignition switch 14 is turned off (step A20). This is for confirming the occupant's intention to use the vehicle.
If this step A20 is YES and the ignition switch 14 is turned off, it can be determined that there is no intention to use the vehicle, and the program is ended (step A21).
However, if this step A20 is NO and the ignition switch 14 is on, the process returns to the step A05 to move to the next flow process, and again from the result of the count number (Co), the failure of the oil temperature sensor 8 or Perform normal judgment. In that case, the process is continued by taking over the previous count number (Co).
However, when the process goes through the step A17 or the step A19, that is, when the oil temperature sensor 8 is determined to be faulty or normal, the flow process is started from the step A03, and the count number (Co) is newly set. Processing may be performed by substituting the initial value (Ci). In this case, the step A04 is not performed, and the flow proceeds to the step A05 to proceed with the flow process.
This flow process is performed while the driver's intention to drive the vehicle continues. Specifically, for example, this is performed between when the ignition switch 14 is turned on and when it is turned off. Therefore, this flow process is continuously executed even during the temporary stop of the engine 1 due to the automatic stop of the engine 1 (engine idle stop or the like).

次に、エンジン１の始動後、油温センサ８の出力値（検出油温Ｔｏ０）が途中から固着した場合の故障診断状況で、つまり、検出油温（Ｔｏ０）とは異なる一定値の油温を検出し続ける固着状態で故障した場合の例を、図５に示す。図５中の第一領域、第二領域若しくは第三領域と判定している期間とは、油温センサ８の検出油温（Ｔｏ０）が、その各々の時間において第一領域、第二領域、第三領域のどの領域にあるかを示している。
図５に示すように、エンジン１の始動後、故障診断を所定期間の時間（ｔｗ）［ｓ］まで待機させている間は、油温センサ８の出力値（検出油温（Ｔｏ０））の正常・異常にかかわらず、カウント数（Ｃｏ）を一定の初期値（Ｃｉ）とする。この診断開始直後から油温センサ８の検出油温（Ｔｏ０）は正常を示し、検出油温（Ｔｏ０）が第二領域にある（図２のステップ１１にてＮＯの判定）ため、カウント数（Ｃｏ）を正常度（Ｃｄ）に応じて減少させていく。
そして、時間（ｔ１）にカウント数（Ｃｏ）が正常判定閾値（Ｃ２）以下になったら、油温センサ８を正常と診断する。
しかし、時間（ｔ２）に油温センサ８が故障し、油温センサ８の検出油温（Ｔｏ０）が一定値を検出し続ける固着状態になると、時間（ｔ３）で第三領域にて正常又は異常のどちらともいえない値（図２のステップＡ１１にてＹＥＳの判定）、時間（ｔ４）で異常といえる値（図２のステップＡ０８の条件が成立）になり、異常度（Ｃｕ）に応じてカウント数（Ｃｏ）を増加させる。その結果、時間（ｔ５）に、カウント数（Ｃｏ）は異常判定閾値（Ｃ１）以上となり、油温センサ８を故障と判定する。 Next, in the failure diagnosis situation when the output value (detected oil temperature To0) of the oil temperature sensor 8 is fixed from the middle after the engine 1 is started, that is, a constant oil temperature different from the detected oil temperature (To0). FIG. 5 shows an example in the case where a failure occurs in the fixed state in which the detection of the continuity is continued. The period determined as the first region, the second region, or the third region in FIG. 5 means that the detected oil temperature (To0) of the oil temperature sensor 8 is the first region, the second region, It shows which area in the third area.
As shown in FIG. 5, the output value of the oil temperature sensor 8 (the detected oil temperature (To0)) is kept while the failure diagnosis is on standby for a predetermined period of time (tw) [s] after the engine 1 is started. Regardless of normality / abnormality, the count number (Co) is set to a constant initial value (Ci). Immediately after the start of the diagnosis, the detected oil temperature (To0) of the oil temperature sensor 8 is normal, and the detected oil temperature (To0) is in the second region (determination of NO in step 11 in FIG. 2). Co) is decreased according to the normality (Cd).
When the count number (Co) becomes equal to or less than the normal determination threshold value (C2) at time (t1), the oil temperature sensor 8 is diagnosed as normal.
However, when the oil temperature sensor 8 breaks down at time (t2) and the detected oil temperature (To0) of the oil temperature sensor 8 continues to detect a constant value, it is normal in the third region at time (t3). A value that cannot be said to be either abnormal (determined as YES at step A11 in FIG. 2), becomes a value that can be considered abnormal at time (t4) (the condition at step A08 in FIG. 2 is satisfied), and depends on the degree of abnormality (Cu) To increase the count (Co). As a result, at time (t5), the count number (Co) becomes equal to or greater than the abnormality determination threshold value (C1), and the oil temperature sensor 8 is determined to be faulty.

また、エンジン１の始動直後から油温センサ８が高い油温を検出し続ける場合の故障診断状況で、つまり、検出油温（Ｔｏ０）とは異なる一定値の油温を検出し続ける固着状態で故障した場合の例を、図６に示す。図６中の第一領域と判定している期間とは、図５と同様に、油温センサ８の検出油温（Ｔｏ０）が、その各々の時間において第一領域の領域にあることを示している。
図６に示すように、エンジン１の始動直後から油温センサ８が故障しており、油温センサ８の検出油温（Ｔｏ０）は、高温側の値を示している。
故障判定を時間（ｔｗ）［ｓ］待機した後、故障診断を行う。油温センサ８の検出油温（Ｔｏ０）は、正常値から大きく離れているため、図２のステップＡ０８にてＹＥＳの判定を行うとともに大きい値の異常度（Ｃｕ）を採り、短時間で油温センサ８を故障確定とする。 In the failure diagnosis situation when the oil temperature sensor 8 continues to detect a high oil temperature immediately after the engine 1 is started, that is, in a fixed state in which a constant oil temperature different from the detected oil temperature (To0) is continuously detected. An example of a failure is shown in FIG. The period determined as the first region in FIG. 6 indicates that the detected oil temperature (To0) of the oil temperature sensor 8 is in the region of the first region at each time, as in FIG. ing.
As shown in FIG. 6, the oil temperature sensor 8 has failed immediately after the engine 1 is started, and the detected oil temperature (To0) of the oil temperature sensor 8 indicates a value on the high temperature side.
After waiting for time (tw) [s] for failure determination, failure diagnosis is performed. Since the detected oil temperature (To0) of the oil temperature sensor 8 is far from the normal value, YES is determined in step A08 of FIG. 2 and a large value of the degree of abnormality (Cu) is taken. The temperature sensor 8 is determined to be faulty.

さらに、図５、図６において、第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）は、時間経過につれて各所定値の温度差が小さくなっている。これは、前述したように、車両が走行することでエンジン水温（Ｔｅ）、自動変速機２の検出油温（Ｔｏ０）が上昇し、車両の外的要因（外気温等）の影響を受け難くなり、自動変速機２の検出油温（Ｔｘ）がエンジン水温（Ｔｅ）から推定しやすいことによる。
故障判定部２５は、故障判定閾値（Ｃ１）若しくは正常判定閾値（Ｃ２）のどちらか一方の判定値（油温閾値）に達した場合、その判定結果を他方の判定値（油温閾値）に達するまで出し続ける。
具体的には、図５において、時間（ｔ１）にて油温センサ８の正常判定がなされたら、その後のカウント数（Ｃｏ）の値によらず、時間（ｔ５）にて油温センサ８の異常判定がなされるまで故障判定部２５は、正常判定を出し続ける。
また、図５、図６において、エンジン１の始動時からの所定期間経た時間（ｔｗ）経過によって、第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）の各所定値の温度差が小さくなっても、故障度（Ｃｕ）、正常度（Ｃｄ）の最大値は、エンジン１の始動時に比べて大きく設定されることはあるが、小さく設定されることはない。これにより、エンジン１の始動の初期に比べて、時間をかけずに油温センサ８の故障判定を行うことができる。
第一所定値（Ｔｏ１）、第三所定値（Ｔｏ３）は、その初期段階で大きく上昇している。これは、乗員によって故意に自動変速機２に負荷がかけられた場合を想定しているためである。例えば、ドライブレンジ（Ｄレンジ）等のシフトポジションとした状態で乗員がブレーキを踏みつつ、アクセル操作が有る場合は、自動変速機２にかかる負荷が通常走行時にくらべて大きい。この場合、自動変速機２の油温上昇傾向は、エンジン水温（Ｔｅ）の上昇とは異なる。特に、エンジン水温（Ｔｅ）が低い状況下では、自動変速の負荷増大による自動変速機２の油温の上昇が著しいためである。但し、上記の条件のうち、いずれか一つでも成立しない場合は、第一所定値（Ｔｏ１）、第三所定値（Ｔｏ３）は、その初期段階で大きくしないようにしても良く、この場合、より油温センサ８の故障判定を正確に行うことができる。 Further, in FIGS. 5 and 6, the temperature difference between the predetermined values of the first predetermined value (To1) to the fourth predetermined value (To4) decreases with time. As described above, this is because the engine water temperature (Te) and the detected oil temperature (To0) of the automatic transmission 2 increase as the vehicle travels, and are not easily affected by external factors (such as the outside air temperature) of the vehicle. This is because the detected oil temperature (Tx) of the automatic transmission 2 is easily estimated from the engine water temperature (Te).
When the failure determination unit 25 reaches one of the determination values (oil temperature threshold) of the failure determination threshold (C1) or the normality determination threshold (C2), the determination result is changed to the other determination value (oil temperature threshold). Continue out until it reaches.
Specifically, in FIG. 5, when the oil temperature sensor 8 is determined to be normal at time (t1), the oil temperature sensor 8 at time (t5) does not depend on the value of the subsequent count number (Co). The failure determination unit 25 continues to issue a normal determination until an abnormality determination is made.
5 and 6, the temperature difference between the predetermined values of the first predetermined value (To1) to the fourth predetermined value (To4) is small with the passage of a predetermined time (tw) from the start of the engine 1. Even if the maximum value of the failure level (Cu) and the normality level (Cd) is set to be larger than that at the time of starting the engine 1, it is not set to be small. Thereby, the failure determination of the oil temperature sensor 8 can be performed without taking time compared with the initial stage of the start of the engine 1.
The first predetermined value (To1) and the third predetermined value (To3) are greatly increased in the initial stage. This is because it is assumed that a load is intentionally applied to the automatic transmission 2 by the occupant. For example, when an accelerating operation is performed while an occupant is stepping on a brake in a shift position such as a drive range (D range), the load on the automatic transmission 2 is greater than that during normal driving. In this case, the oil temperature rising tendency of the automatic transmission 2 is different from the engine water temperature (Te) increase. Particularly, when the engine water temperature (Te) is low, the oil temperature of the automatic transmission 2 is significantly increased due to an increase in the load of automatic transmission. However, if any one of the above conditions is not satisfied, the first predetermined value (To1) and the third predetermined value (To3) may not be increased in the initial stage. Therefore, the failure determination of the oil temperature sensor 8 can be performed accurately.

なお、この発明は、上記の実施例に限定されず、種々応用改変が可能であることは勿論である。
例えば、エンジン水温の他に外気温度やエンジン吸入空気温度の検出結果を組み合わせて、自動変速機の油温を推定する構成としても可能である。これにより、異常度（Ｃｕ）、正常度（Ｃｄ）が零（０）となる第三領域を狭めることが可能となり、より早期に油温センサの故障判定を行うことができる。この場合、複数の異なる外気温若しくはエンジン吸入空気温度条件の下でのエンジン水温おける図３、図４と同様のマップデータを用意する構成とする。
また、油温センサの断線、ショート故障診断への応用を図る。油温センサの断線時に出力される温度、ショート時に出力される油温に応じて所定値（油温閾値）を設定し、カウント数（Ｃｏ）や診断時間を車両のパラメータ（エンジン温度等）に応じて可変にすることで、診断までの時間を短縮することが可能となる。
更に、エンジン温度検出手段の故障診断、油温センサの故障診断として、同様の故障判定を行うことも可能である。
更にまた、第一所定値（Ｔｏ１）〜第四所定値（Ｔｏ４）を決定する指標として、エンジン水温を挙げたが、他に、以下の車両のパラメータ（１）〜（４）が挙げられる。
（１）、エンジン水温の代わりに、エンジン油温やエンジン吸入空気温度を用い、又は、それらのパラメータとの組み合わせることで、より正確に各所定値（油温閾値）を設定することができるとともに、より早期に油温センサの故障判定を行うこともできる。
（２）、自動変速機内に２つ以上の油温センサが搭載されている場合、油温センサからの出力値を診断する代わりに、油温センサからの出力値の差分を診断する。また、それらのパラメータを組み合わせることもできる。
（３）、実際の走行データを基にして、車両のパラメータ（エンジン水温、エンジン始動時間、走行距離等）を軸とした各所定値（油温閾値）のマップを予め作成し、それを基に各所定値を導出する。
（４）、エンジンから自動変速機に伝わる熱（エンジン水温、エンジン油温から推定）、自動変速機の内部で発生する熱（エンジントルクと車両の加速度から推定）、自動変速機が放出する熱（ラジエータの性能、エンジン吸入空気温度、車速から推定）を基に所定値（油温閾値）を導出する。
また、前回のエンジンの始動時間と、前回のエンジンのオフから今回のエンジンのオンまでの時間を取得し、前回のエンジンの始動時間とオフ時間とを取得することで、エンジンの始動後間もないエンジン水温や自動変速機の油温の状態を考慮した故障を行うことができ、また、図２のステップＡ０３における初期値（Ｃｉ）の値もより正確に求めることができる。 Of course, the present invention is not limited to the above-described embodiments, and various application modifications are possible.
For example, the oil temperature of the automatic transmission can be estimated by combining the detection results of the outside air temperature and the engine intake air temperature in addition to the engine water temperature. As a result, the third region where the degree of abnormality (Cu) and the degree of normality (Cd) are zero (0) can be narrowed, and the failure determination of the oil temperature sensor can be performed earlier. In this case, the same map data as in FIGS. 3 and 4 is prepared for the engine water temperature under a plurality of different outside air temperature or engine intake air temperature conditions.
In addition, it will be applied to disconnection of oil temperature sensor and short failure diagnosis. A predetermined value (oil temperature threshold) is set according to the temperature output when the oil temperature sensor is disconnected and the oil temperature output when short-circuited, and the count number (Co) and diagnosis time are used as vehicle parameters (engine temperature, etc.). By making it variable accordingly, it is possible to shorten the time to diagnosis.
Furthermore, the same failure determination can be performed as failure diagnosis of the engine temperature detection means and failure diagnosis of the oil temperature sensor.
Furthermore, the engine water temperature is cited as an index for determining the first predetermined value (To1) to the fourth predetermined value (To4), but the following vehicle parameters (1) to (4) are also included.
(1) Instead of the engine water temperature, each predetermined value (oil temperature threshold) can be set more accurately by using the engine oil temperature or the engine intake air temperature, or by combining them with those parameters. The failure determination of the oil temperature sensor can be performed earlier.
(2) When two or more oil temperature sensors are mounted in the automatic transmission, the difference between the output values from the oil temperature sensor is diagnosed instead of diagnosing the output value from the oil temperature sensor. These parameters can also be combined.
(3) Based on the actual driving data, a map of each predetermined value (oil temperature threshold) with the vehicle parameters (engine water temperature, engine starting time, driving distance, etc.) as axes is created in advance. Each predetermined value is derived.
(4) Heat transmitted from the engine to the automatic transmission (estimated from engine water temperature and engine oil temperature), heat generated inside the automatic transmission (estimated from engine torque and vehicle acceleration), heat released by the automatic transmission A predetermined value (oil temperature threshold) is derived based on (estimated from the performance of the radiator, the engine intake air temperature, and the vehicle speed).
Also, by acquiring the previous engine start time and the time from the previous engine off to the current engine on, and obtaining the previous engine start time and off time, It is possible to perform a failure taking into account the state of the engine water temperature and the oil temperature of the automatic transmission, and the initial value (Ci) in step A03 in FIG. 2 can be determined more accurately.

この発明に係る油温センサの故障判定装置を、各車両の変速機に適用可能である。 The oil temperature sensor failure determination device according to the present invention can be applied to a transmission of each vehicle.

１エンジン
２自動変速機
３制御手段
４油温センサの故障判定装置
８油温センサ
１２水温センサ
１４イグニションスイッチ
２５故障判定部
２５Ａ油温推定部
２５Ｂ故障判定閾値決定部
２５Ｃ故障指数決定部
２５Ｄ故障指数カウント部
２５Ｅ油温閾値決定部
２５Ｆ正常判定閾値決定部
２５Ｇ正常指数決定部 DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Control means 4 Oil temperature sensor failure determination apparatus 8 Oil temperature sensor 12 Water temperature sensor 14 Ignition switch 25 Failure determination part 25A Oil temperature estimation part 25B Failure determination threshold value determination part 25C Failure index determination part 25D Failure index Count unit 25E Oil temperature threshold value determination unit 25F Normal determination threshold value determination unit 25G Normal index determination unit

Claims

An engine that is a power source of the vehicle is provided, an automatic transmission that transmits the output of the engine to the drive wheels of the vehicle is provided, engine temperature detection means that detects the temperature of the engine is provided, and the oil temperature of the automatic transmission is reduced. In a vehicle oil temperature sensor failure determination apparatus provided with an oil temperature sensor for detection and provided with a control means including a failure determination unit for determining a failure of the oil temperature sensor, the failure determination unit includes: An oil temperature estimation unit that estimates an oil temperature of the automatic transmission from an engine temperature detection result to obtain an estimated oil temperature, and a failure determination that determines a failure determination threshold value for determining that the oil temperature sensor has failed A threshold value determination unit, and a failure index determination unit that calculates a failure index that increases as the oil temperature difference between the estimated oil temperature obtained by the oil temperature estimation unit and the detected oil temperature of the oil temperature sensor increases. Asked for That a plurality of failure determination device for an oil temperature sensor count number is total and judging with the oil temperature sensor by reaching the failure determination threshold value is faulty the fault index.

The failure determination unit includes a first predetermined value serving as a reference for obtaining the failure index, a second predetermined value smaller than the first predetermined value, and a temperature at which the detected oil temperature is larger than the first predetermined value. When a first region that is a region or a temperature region smaller than the second predetermined value is set, and the detected oil temperature is in the first region, the failure index indicates the count number to the failure determination threshold value side. The oil temperature sensor failure determination device according to claim 1, wherein a value that approaches is adopted.

The failure determination unit includes a normal determination threshold value determination unit that determines a normal determination threshold value that determines that the oil temperature sensor is functioning normally, and a normality index that is added so as to keep the count number away from the failure determination threshold value. A normal index determining unit to determine, a third predetermined value serving as a reference for determining the normal index, a fourth predetermined value smaller than the third predetermined value, and the detected oil temperature is lower than the third predetermined value When the second region which is a temperature region that is smaller and larger than the fourth predetermined value is set, and the detected oil temperature is in the second region, the failure number is determined as the oil temperature difference is smaller. The failure determination device for an oil temperature sensor according to claim 1 or 2, wherein the failure determination device is further away from a threshold value and closer to the normal determination threshold value.

The failure determination unit sets the difference between the failure determination threshold and the normal determination threshold smaller as the engine water temperature becomes higher, sets the difference between the first predetermined value and the second predetermined value smaller, The oil temperature sensor failure determination device according to any one of claims 1 to 3, wherein a difference between a third predetermined value and the fourth predetermined value is set to be small.

The failure determination unit has a magnitude relationship in which the first predetermined value is large between the first predetermined value and the third predetermined value, and the second predetermined value is small between the second predetermined value and the fourth predetermined value. A third temperature range in which the detected oil temperature is smaller than the first predetermined value and larger than the third predetermined value, or the detected oil temperature is larger than a second predetermined value and smaller than the fourth predetermined value. When the region is set and the detected oil temperature is in the third region, the value added to the count number is that both the failure index and the normal index are zero. Item 5. The oil temperature sensor failure determination device according to any one of Items4.

The failure determination unit takes an intermediate value between the failure determination threshold value and the normality determination threshold value at the time of starting the failure determination process of the oil temperature sensor as an initial value set to the count number. The failure determination device for an oil temperature sensor according to any one of claims 1 to 5.