Method For Processing A Temperature Sensor Signal

• US 20100161270A1
• Filed: 12/18/2008
• Published: 06/24/2010
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: Discovery Energy LLC
• Original Assignee: Kohler Company
• Inventors: Jayasheela, Vijit Paul
• Granted Patent: US 8,478,558 B2
• Time in Patent Office: Days
• US Class Current: 702/130
• CPC Class Codes: G01K 7/25 for modifying the output characteristic, e.g. linearising
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A method for processes a pulse width modulated signal from a temperature sensor, wherein the signal varies non-linearly and non-exponentially with changes in temperature. An exponential equation is defined that is closely fitted to the relationship between a characteristic of the signal and the temperature. The signal from the sensor is processed by measuring the characteristic to produce a sensor value. That sensor value then is employed to solve the exponential equation which produces a value for the temperature.

Claims

1. A method for processing a signal from a sensor on an apparatus, wherein the signal has a characteristic that varies non-linearly and non-exponentially with changes in a parameter being sensed, said method comprising:

defining an exponential equation that specifies a relationship between the signal from the sensor and the parameter being sensed;

receiving the signal from the sensor;

measuring the characteristic of the signal to produce a sensor value; and

using the sensor value to solve an exponential equation which produces a value for the parameter.

2. The method as recited in claim 1 wherein the relationship between the signal from the sensor and the parameter is dependent upon an initial temperature of the apparatus, and wherein the exponential equation has a term corresponding to the initial temperature;

and the method further comprises sensing the initial temperature of the apparatus to produce an initial temperature value and using that initial temperature value in subsequently solving the exponential equation.

3. The method as recited in claim 2 wherein the initial temperature occurs when the apparatus starts operating.

4. The method as recited in claim 1 wherein the relationship between the signal from the sensor and the parameter being sensed is dependent upon a steady state operating temperature of the apparatus, and wherein the exponential equation contains a term corresponding to the steady state operating temperature.

5. The method as recited in claim 1 wherein the exponential equation is given by:

$T=T_{\mathrm{\infty <br><br>}}+\frac{T_i-T_{\mathrm{\infty <br><br>}}}{e^{\mathrm{kt}}}$

where T is the value for the parameter, T_∞

is a steady state operating temperature of the apparatus, T_i is an initial temperature of the apparatus, k is an exponential constant, and t is the sensor value.

6. The method as recited in claim 5 wherein the exponential constant k is defined based on at least one operating characteristic of the sensor.

7. The method as recited in claim 1 wherein the signal from the sensor is pulse width modulated to indicate the parameter being sensed.

8. The method as recited in claim 1 wherein the signal from the sensor has a portion that varies in duration to indicate the parameter being sensed.

9. A method for processing a signal from a temperature sensor on an engine, wherein the signal has a characteristic that varies non-linearly and non-exponentially with engine temperature changes, said method comprising:

defining an exponential equation that specifies a relationship between the signal from the temperature sensor and the engine temperature;

receiving the signal from the temperature sensor;

measuring the characteristic of the signal to produce a sensor value; and

using the sensor value to solve an exponential equation which produces a value for the engine temperature.

10. The method as recited in claim 9 wherein the relationship between the signal from the temperature sensor and the engine temperature is dependent upon an initial temperature when the engine starts operating, and wherein the exponential equation contains a term corresponding to the initial temperature.

11. The method as recited in claim 9 wherein the relationship between the signal from the sensor and temperature being sensed is dependent upon a steady state operating temperature of the engine, and wherein the exponential equation contains a term corresponding to the steady state operating temperature.

12. The method as recited in claim 9 wherein the exponential equation is given by:

$T=T_{\mathrm{\infty <br><br>}}+\frac{T_i-T_{\mathrm{\infty <br><br>}}}{e^{\mathrm{kt}}}$

where T is the value for the engine temperature, T_∞

is a steady state operating temperature of the engine, T_i is an initial temperature of the engine, k is an exponential constant, and t is the sensor value.

13. The method as recited in claim 12 wherein the exponential constant k is defined based on the relationship between the signal from the temperature sensor and the engine temperature.

14. The method as recited in claim 9 wherein the signal from the sensor is pulse width modulated to indicate the engine temperature.

15. The method as recited in claim 9 wherein the signal from the sensor has a portion that varies in duration to indicate the engine temperature.

16. A method for processing a pulse width modulated signal from a temperature sensor on an engine, wherein a portion of the signal has a duration that varies non-linearly and non-exponentially with engine temperature changes, said method comprising:

defining an exponential equation that specifies a relationship between variation of the signal from the temperature sensor and the engine temperature;

receiving the signal from the temperature sensor;

measuring the duration the portion of the signal to produce a sensor value; and

using the sensor value to solve an exponential equation which produces a value for the engine temperature.

17. The method as recited in claim 16 wherein the exponential equation is given by:

$T=T_{\mathrm{\infty <br><br>}}+\frac{T_i-T_{\mathrm{\infty <br><br>}}}{e^{\mathrm{kt}}}$

where T is the value for the engine temperature, T_∞

is a steady state operating temperature of the engine, T_i is an initial temperature of the engine, k is an exponential constant, and t is the sensor value.

18. The method as recited in claim 17 wherein the exponential constant k is defined based on the relationship between the signal from the temperature sensor and the engine temperature.

19. The method as recited in claim 16 wherein the exponential equation contains a term corresponding to an initial temperature of the engine.

20. The method as recited in claim 16 wherein the exponential equation contains a term corresponding to a steady state operating temperature of the engine.