Method for detecting malfunction of a cooling system based on detected coolant temperature

• US 7,363,804 B2
• Filed: 10/17/2006
• Issued: 04/29/2008
• Est. Priority Date: 12/17/1996
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Wakahara, Keiji, Ichikawa, Akira
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US11/581,362
• Publication Number:
  US 20070033998A1
• Time in Patent Office: 560 Days
• Field of Search: 731/16, 731/172, 731/173, 731/181, 731/19.R
• US Class Current: 73/114.39
• CPC Class Codes: F01P 11/14 Indicating devices; Other safety devices
• CPC Class Codes: F01P 11/16 concerning coolant temperature F01P11/20 takes precedence
• CPC Class Codes: F01P 2023/00 Signal processing; Details thereof
• CPC Class Codes: F01P 2023/08 Microprocessor; Microcomputer
• CPC Class Codes: F01P 2025/08 Temperature
• CPC Class Codes: F01P 2025/13 Ambient temperature
• CPC Class Codes: F01P 2025/62 Load
• CPC Class Codes: F01P 2025/64 Number of revolutions
• CPC Class Codes: F01P 2025/66 Vehicle speed
• CPC Class Codes: F01P 2031/00 Fail safe
• CPC Class Codes: F01P 2031/20 Warning devices
• CPC Class Codes: F01P 2060/14 Condenser
• CPC Class Codes: F01P 5/02 Pumping cooling-air; Arrangements of cooling-air pumps, e.g. fans or blowers
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 41/18 by measuring intake air flow
• 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: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A malfunction of a thermostat in a coolant circulating path is detected from an engine side coolant temperature in consideration of the following behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes different considerably from that in the normal time in the temperature range in which the thermostat is to be normally closed. When a closure-malfunction occurs, the coolant temperature becomes different considerably from that during the normal time in the temperature range in which the thermostat is to be normally opened. Alternatively, the malfunction may be detected from a difference between the engine side coolant temperature and a radiator side coolant temperature.

Claims

1. A method for detecting a malfunction of a cooling system of an internal combustion engine, comprising:

detecting a coolant temperature on a side of the engine; and

determining, when a parameter related to an intake air amount reaches a predetermined value, a malfunction of a cooling system based on the detected coolant temperature,

wherein the malfunction determination uses the coolant temperature detected at an engine start time.

2. The method as in claim 1, wherein the parameter is calculated based on an accumulation of an intake air amount from the engine start time.

3. The method as in claim 1, wherein the parameter is calculated based on an amount of heat radiation generated by the engine.

4. The method as in claim 3, wherein the amount of heat radiation is calculated based on a vehicle speed.

5. The method as in claim 3, wherein the amount of heat radiation is calculated based on an intake air temperature.

6. The method as in claim 3, wherein the amount of heat radiation is calculated based on an air conditioner operation condition.