Thermostat setting diagnostics for internal combustion engine
First Claim
1. Apparatus for measuring the operation of the thermostat mounted in an engine cooling system with the engine running, comprising:
- pressure sensor means adapted to be disposed to sense the pressure of the coolant of the cooling system, and providing a pressure signal in response thereto;
temperature sensor means adapted to be disposed to sense the temperature of the coolant in said cooling system and provide a temperature signal in response thereto; and
processing apparatus comprising means operative in response to said temperature and to said pressure signals with all of said sensor means disposed as described hereinbefore for determining a variation in either of said signals indicative of thermostat operation.
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Accused Products
Abstract
Electronic processing means are utilized in a composite measurement of performance of an engine cooling system thermostat, with diagnostic procedures to ensure viable measurement. The speed of the engine is initially tested to ensure the engine is at high idle speed, so that temperature in the cooling system will increase to that at which the thermostat will normally operate; and during the testing, the speed is continuously monitored to be sure it remains close to the initial test speed (near high idle) to minimize coolant pump pressure variations due to engine speed. Three temperature diagnostics are performed to ensure a viable test: first, if the temperature ever exceeds 15° over the rated thermostat temperature, the test is terminated in a fault since the thermostat is presumed to be stuck in the closed position; second, if the temperature fails to increase by at least 2° for each 2 minutes of operation above rated speed, the test is terminated in a fault since it is assumed that the thermostat is stuck in the open position; third, if the test is not completed within 5 minutes after the temperature reaching 5° less than the rated thermostat temperature, the test is terminated in a fault since the thermostat operation is too imprecise to reliably perform the measurements of the operation (such as laggardly or stuck partially open). The actual thermostat operation measurements are the highest temperature reached before sensing either a temperature drop of 2° below the highest temperature sensed theretofore, or sensing a pressure drop of 5 psi below the highest pressure sensed theretofore.
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Citations
25 Claims
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1. Apparatus for measuring the operation of the thermostat mounted in an engine cooling system with the engine running, comprising:
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pressure sensor means adapted to be disposed to sense the pressure of the coolant of the cooling system, and providing a pressure signal in response thereto; temperature sensor means adapted to be disposed to sense the temperature of the coolant in said cooling system and provide a temperature signal in response thereto; and processing apparatus comprising means operative in response to said temperature and to said pressure signals with all of said sensor means disposed as described hereinbefore for determining a variation in either of said signals indicative of thermostat operation. - View Dependent Claims (2)
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3. Apparatus for measuring the operation of the thermostat mounted in an engine cooling system with the engine running, comprising:
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pressure sensor means adapted to be disposed to sense the pressure of the coolant of the cooling system, and providing a pressure signal in response thereto; temperature sensor means adapted to be disposed to sense the temperature of the coolant in said cooling system and provide a temperature signal in response thereto; speed sensor means, including means adapted to be disposed to sense rotation of the engine, for providing a speed signal indicative of the speed of rotation of the engine; signal responsive means for providing in response to signals applied thereto a manifestation of thermostat operation; and processing apparatus comprising means operative in response to said pressure signal, said temperature signal and to said speed signal with all of said sensor means disposed as described hereinbefore for successively sampling all of said signals in an interspersed fashion, for continuously comparing successively sampled values of said pressure signals and of said temperature signals, respectively, and in response to variation in either of them by an amount sufficient to indicate thermostat operation, providing signals to said signal responsive means to cause it to provide a manifestation of thermostat operation, and for continuously comparing successively sampled values of said speed signal and in response thereto terminating said interspersed sampling in response to said speed signal values indicating an excessive variation in the speed of said engine. - View Dependent Claims (4, 5, 6, 7)
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8. Apparatus for measuring the operation of the thermostat mounted in an engine cooling system having a thermostat bypass with the engine running, comprising:
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sensor means adapted to be disposed for response to parameters of the coolant of the cooling system which are indicative of thermostat operation and indicative of the temperature of coolant circulating in the cooling system through the bypass, and for providing signals indicative thereof; signal responsive means for providing in response to signals applied thereto a manifestation of thermostat operation; and processing apparatus comprising means operative in response to the signals of said sensor means with said sensor means disposed as described hereinbefore for successively sampling signals of said sensor means, for comparing values of said signals indicative of thermostat operation and in response to a significant variation therein providing signals to said signal responsive means to cause it to provide a manifestation of the operation of said thermostat, and for comparing values of said signals indicative of temperature of the coolant circulating in the cooling system through the bypass and terminating said successive samplings in response to indications that the thermostat is stuck in one position. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. Apparatus for measuring the operation of the thermostat mounted in an engine cooling system having a thermostat bypass with the engine running, comprising:
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sensor means adapted to be disposed for response to the temperature of coolant circulating in the cooling system through the bypass and providing a temperature signal indicative thereof; pressure sensor means adapted to be disposed for response to the pressure of the coolant circulating in the cooling system with the thermostat closed and providing a pressure signal indicative thereof; and processing apparatus operative in a repetitive process in response to said sensor means with said sensors disposed for response as described hereinbefore, for successively sampling all of said signals, for comparing successively sampled values of said signals, for providing, in response to sensing either a variation in said temperature signal values or a variation in said pressure signal values indicative of thermostat operation, a manifestation of thermostat operation and terminating said process, and for otherwise terminating said process in response to successively samples values of said temperature indicating a failure of said temperature to maintain a given temperature rise per unit of time, said temperature exceeding the rated temperature of the thermostat by on the order of several degrees, or said process having continued over a period of time of on the order of several minutes after said temperature first reaches a given temperature which is a substantial fraction of the rated temperature of the thermostat.
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16. In the method of measuring the operation of the thermostat mounted in the cooling system of an engine, the steps of:
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operating the engine so that the temperature of the coolant in the cooling system will increase from a temperature below the rated thermostat temperature; monitoring parameters of the coolant in the cooling system including temperature and pressure; and providing, in response to a change in one of said parameters sufficient to indicate thermostat operation, an indication of one of said parameters. - View Dependent Claims (17, 18, 19, 20, 21)
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22. In the method of monitoring a parameter of an engine cooling system having a thermostat bypass, to sense the operation of a thermostat mounted therein with the engine running, the steps of:
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monitoring the temperature of coolant circulating in the cooling system through the thermostat bypass; and terminating the method in the event that said temperature indicates that the thermostat is stuck.
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23. In the method of monitoring a parameter of an engine cooling system having a thermostat bypass, to sense the operation of a thermostat mounted therein with the engine running, the steps of:
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monitoring the temperature of coolant circulating in the cooling system through the thermostat bypass; and terminating the method in the event that said temperature fails to maintain a temperature rise of a given magnitude per unit of time.
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24. In the method of monitoring a parameter of an engine cooling system having a thermostat bypass, to sense the operation of a thermostat mounted therein with the engine running, the steps of:
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monitoring the temperature of coolant circulating in the cooling system through the thermostat bypass; and terminating the method in the event that said temperature exceeds the rated thermostat temperature by on the order of several degrees.
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25. In the method of monitoring a parameter of an engine cooling system having a thermostat bypass, to sense the operation of a thermostat mounted therein with the engine running, the steps of:
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monitoring the temperature of coolant circulating in the cooling system through the thermostat bypass; and terminating the method in the event that the method continues over a period of time on the order of several minutes after said temperature first reaches a given, substantial fraction of the rated thermostat temperature for the cooling system under test.
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Specification