Method for detecting cooling system faults
First Claim
1. A method for diagnosing a thermostat in an internal combustion engine, the method comprising:
- estimating an engine coolant temperature based on an operating condition and a characteristic of the thermostat;
reading said engine coolant temperature;
determining that the thermostat performance is degraded if said reading agrees with said estimate in a first operating region, and said reading disagrees with said estimate in a second operating region; and
indicating that said engine coolant temperature sensor performance is degraded if said estimate and said reading disagree for temperatures below and above said specified temperature.
2 Assignments
0 Petitions
Accused Products
Abstract
A method for diagnosing engine thermostat is presented. Indicated engine coolant temperature is estimated based on engine operating conditions, such as engine speed, net engine torque, air flow, fuel-air ratio, net engine torque, etc. This estimate is compared to the reading of the engine coolant temperature sensor in areas below the temperature at which the thermostat starts to open and above in order to detect degradation in the performance of the sensor or the engine thermostat. If the estimate and the reading agree in one area and disagree in the other, then the thermostat performance is degraded. If the estimate and the reading disagree in both temperature ranges, then the coolant sensor performance may be degraded.
-
Citations
14 Claims
-
1. A method for diagnosing a thermostat in an internal combustion engine, the method comprising:
-
estimating an engine coolant temperature based on an operating condition and a characteristic of the thermostat;
reading said engine coolant temperature;
determining that the thermostat performance is degraded if said reading agrees with said estimate in a first operating region, and said reading disagrees with said estimate in a second operating region; and
indicating that said engine coolant temperature sensor performance is degraded if said estimate and said reading disagree for temperatures below and above said specified temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method for diagnosing a thermostat in an internal combustion engine, the method comprising:
-
estimating an engine coolant temperature based on an operating condition and a characteristic of the thermostat;
reading engine coolant temperature from an engine coolant temperature sensor;
comparing said estimate to said reading;
determining that the thermostat is stuck closed if said estimate and said reading agree for temperatures below a specified temperature, and said estimate and said reading disagree for temperatures above said specified temperature; and
determining that the thermostat is stuck open if said estimate and said reading agree for temperatures above a specified temperature, and said estimate and said reading disagree for temperatures below said specified temperature; and
indicating that said engine coolant temperature sensor performance is degraded if said estimate and said reading disagree for temperatures below and above said specified temperature. - View Dependent Claims (12, 13, 14)
-
Specification