Device for detecting deterioration of a catalyst temperature sensor

• US 5,388,454 A
• Filed: 12/08/1993
• Issued: 02/14/1995
• Est. Priority Date: 09/05/1990
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Iwata, Yoichi, Kuroda, Shigetaka
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Ashraf, Nashmiya
• Application Number:
  US08/164,685
• Time in Patent Office: 433 Days
• Field of Search: 73/118.1, 73/117.3, 73/116, 340/449, 340/459, 60/277, 374/144, 123/693, 123/688
• US Class Current: 73/114.75
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A device for detecting deterioration of a catalyst temperature sensor which detects the temperature of a three-way catalyst arranged in the exhaust pipe of an internal combustion engine, judges that the sensor has deteriorated when the difference between the actual output value from the catalyst temperature sensor and a reference value based on predetermined engine operating parameters exceeds a predetermined value while the engine is in a predetermined operating condition.

Claims

1. A device for detecting deterioration of a catalyst temperature sensor for detecting a value of the temperature of a catalyst for purifying noxious ingredients of exhaust gases in an internal combustion engine, and providing an electrical signal indicative of the detected value, the device comprising:

a plurality of sensors for providing electrical sensor signals having values indicative of particular operating parameters of said engine;

determining means for processing said electrical sensor signals to determine whether or not (i) a difference between an actual output value from said catalyst temperature sensor and a reference value which should be outputted from said catalyst temperature sensor based upon values of said particular operating parameters of said engine indicated by said electrical sensor signals when said engine is in a certain operating condition, determined when a value of at least one of said particular operating parameters is in a predetermined range, exceeds (ii) a predetermined value while said engine is in said certain operating condition;

judging means for providing a warning signal indicating that deterioration of said catalyst temperature sensor has occurred, when said determining means determines that said difference exceeds said predetermined value while said engine is in said certain operating condition; and

alarm generating means responsive to said warning signal for generating an alarm when said judging means has judged that deterioration of said catalyst temperature sensor has occurred.

2. The device according to claim 1, wherein said certain operating condition of said engine is an operating condition in which at least one of said values of said particular operating parameters indicated by said plurality of sensors lies within a predetermined intermediate range.

3. The device according to claim 1 or 2, wherein said plurality of sensors include at least one of an intake temperature sensor for detecting the temperature of intake air supplied to said engine, an engine temperature sensor for detecting the temperature of a coolant of said engine, and an engine rotational speed sensor for detecting the rotational speed of said engine, or an intake pressure sensor for detecting intake pressure of said engine.

4. The device according to claim 1 or 2, wherein said judging means judges that deterioration of said catalyst temperature sensor has occurred when said difference has continuously exceeded said predetermined value for a predetermined time period.

5. A device for detecting deterioration of a catalyst temperature sensor for detecting the temperature of a catalyst for purifying noxious ingredients of exhaust gases in an internal combustion engine, and providing an electrical signal indicative of the detected value, the device comprising:

a plurality of engine operating parameter sensors including at least one of (i) an intake temperature sensor for detecting the temperature of intake air supplied to said engine, (ii) an engine temperature sensor for detecting the temperature of a coolant of the engine, (iii) an engine rotational speed sensor for detecting the rotational speed of said engine, or (iv) an intake pressure sensor for detecting intake pressure of said engine, for providing electrical sensor signals having values indicative of values of particular operating parameters of said engine;

an electronic control unit including an input circuit responsive to said electrical sensor signals, a central processing unit coupled to said input circuit, a memory coupled to said central processing unit, and an output circuit coupled to said central processing unit, said electronic control unit including

(a) determining means for determining whether or not (i) a difference between an actual output value from said catalyst temperature sensor and a reference value which should be outputted from said catalyst temperature sensor based upon values of said particular operating parameters of said engine corresponding to said electrical sensor signals when said engine is in a certain operating condition, determined when a value of at least one of said particular operating parameters is in a predetermined range, exceeds (ii) a predetermined value while said engine is in said certain operating condition, and

(b) judging means for judging that deterioration of said catalyst temperature sensor has occurred when said determining means determines that said difference exceeds said predetermined value while said engine is in said certain operating condition; and

alarm generating means coupled to said electronic control unit for generating an alarm when said judging means has judged that deterioration of said catalyst temperature sensor has occurred.