INTAKE AIR TEMPERATURE (IAT) RATIONALITY DIAGNOSTIC WITH AN ENGINE BLOCK HEATER
First Claim
1. A method of conducting an intake air temperature (IAT) rationality test in a vehicle with an engine having an engine block heater, said method comprising the steps of:
- determining that vehicle soak conditions meet predetermined criteria for the test, including a duration of a soak period and commencing the test at a start-up time; and
determining whether the engine block heater was operated during the soak period; and
discontinuing the rationality test when the engine block heater has been determined to have been operated during the soak period.
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Accused Products
Abstract
A first method is suitable for vehicles having an ambient temperature sensor and employs an estimation model configured to estimate a minimum start-up engine coolant temperature (SUECT) if the engine block heater was operated during the previous soak period. A measured SUECT is then compared to estimated minimum SUECT from the model, and if it is higher, then the diagnostic logic concludes that the engine block heater was operated during the soak period, and disables the reporting its test results. A second method is suitable for vehicles without an ambient (soak) temperature sensor employs an alternative approach. Predetermined data based on actual vehicle testing over a wide range of conditions is stored in a data structure. The data describe respective minimum and maximum start-up IAT thresholds versus SUECT. The thresholds are spaced apart to define a start-up IAT window in between. In other words, the window is bounded by minimum and maximum start-up IAT thresholds. For any measured SUECT, a particular window will be set. If the measured start-up IAT falls within the window, then the engine block heater was operated during the soak period.
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Citations
21 Claims
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1. A method of conducting an intake air temperature (IAT) rationality test in a vehicle with an engine having an engine block heater, said method comprising the steps of:
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determining that vehicle soak conditions meet predetermined criteria for the test, including a duration of a soak period and commencing the test at a start-up time; and determining whether the engine block heater was operated during the soak period; and discontinuing the rationality test when the engine block heater has been determined to have been operated during the soak period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a vehicle having an engine with an engine block heater, a method of determining whether the engine block heater was operated during a soak period, comprising the steps of:
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verifying that boundary conditions for use of an ECT estimation model are satisfied. estimating a minimum engine coolant temperature (ECT) at a start-up time in accordance with the ECT estimation model; and determining whether the engine block heater was operated during the soak period based on a comparison of a start-up ECT and the estimated minimum ECT from the model. - View Dependent Claims (15, 16, 17)
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18. In a vehicle having an engine with an engine block heater, a method of determining whether the engine block heater was operated during a soak period, comprising the steps of:
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verifying that predetermined predicate conditions based on a start-up engine coolant temperature (SUECT) and a start-up intake air temperature (SUIAT) are satisfied wherein the SUECT and SUIAT are taken after the soak period upon start-up of the engine; determining respective minimum and maximum SUIAT thresholds using predetermined SUIAT data as a function of the SUECT; and determining whether the engine block heater was operated during the soak period based on a comparison of the SUIAT and the minimum and maximum SUIAT thresholds. - View Dependent Claims (19, 20, 21)
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Specification