SYSTEM AND METHOD FOR TEMPERATURE SENSING IN AN INTERNAL COMBUSTION ENGINE

• US 20160195454A1
• Filed: 01/02/2015
• Published: 07/07/2016
• Est. Priority Date: 01/02/2015
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Edwards, William E., Garrard, Michael R.
• Granted Patent: US 9,909,932 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01K 13/08 in rotary movement
• CPC Class Codes: G01K 7/18 the element being a linear resistance, e.g. platinum resistance thermometer G01K7/26 takes precedence
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A system for determining a temperature of a first portion of an engine, and related circuit, and related method of operation, are disclosed. In one example embodiment, the system includes a wheel having a plurality of magnetic teeth, and an electrical circuit including a variable reluctance sensor (VRS) including at least one winding, the VRS being positioned proximate the wheel, where the VRS is in thermal contact with the first portion, and a comparator having first and second input terminals and an output terminal, where the comparator is configured to output an output signal at the output terminal. Either the output signal or a further signal generated by the electrical circuit is at least indirectly indicative of a resistance of the at least one winding, whereby an indication of the temperature of the first portion can be determined based upon the output signal or further signal.

Claims

1. A system for determining a temperature of a first portion of an internal combustion engine, the system comprising:

a wheel having a plurality of magnetic teeth spaced around a perimeter of the wheel, the wheel being coupled at least indirectly to a crankshaft of the engine so that a wheel rotational speed is at least indirectly related to a crankshaft rotational speed;

an electrical circuit including

a variable reluctance sensor (VRS) including at least one winding, the VRS being positioned proximate the wheel so that the magnetic teeth pass by the VRS during rotation of the wheel, wherein the VRS is mounted on the engine so as to be in thermal contact with the first portion of the engine;

a comparator having first and second input terminals and an output terminal, wherein the at least one winding is electrically coupled to the first input terminal, and wherein the comparator is configured to output an output signal at the output terminal that is indicative of whether a first voltage applied to the first input terminal is lesser or greater than a second voltage applied to the second input terminal;

wherein either the output signal or a further signal generated by the electrical circuit is at least indirectly indicative of a resistance of the at least one winding,

whereby an indication of the temperature of the first portion of the engine can be determined based upon the output signal or further signal that is at least indirectly indicative of the resistance.

5. The system of claim 1, wherein the electrical circuit further includes at least one additional component that is also electrically coupled to the first input terminal or to the second input terminal, wherein the at least one additional component includes a current source that is electrically coupled to the first input terminal.

6. The system of claim 5, wherein the current source is electrically coupled to the first input terminal by way of a switch.

7. The system of claim 5, wherein the current source is configured to generate a forcing current that is communicated to the at least one winding.

8. The system of claim 5, wherein the at least one additional component includes a voltage detection threshold device that is coupled to the second input terminal and configured to apply at least one voltage to the second terminal, wherein the at least one voltage includes the second voltage.

9. The system of claim 8, wherein the voltage detection threshold device is configured to be controllable so as to apply each of the second voltage to the second terminal and a third voltage to the second terminal.

10. The system of claim 1, further comprising an electronic control module (ECM) that is electrically coupled to the output terminal.

11. The system of claim 10, wherein the electrical circuit further includes at least one additional component that is also electrically coupled to the first input terminal or to the second input terminal, wherein the at least one additional component includes a switch, a current source device that is electrically coupled to the first input terminal by way of the switch, and a voltage detection threshold device that is electrically coupled to the second input terminal.

12. The system of claim 11, wherein the ECM is configured to provide at least one control signal to one or more of the switch, the current source device, and the voltage detection threshold device at a time when an output signal from the output terminal does not indicate that one of the magnetic teeth is substantially aligned with the VRS.

13. The system of claim 1, wherein the electrical circuit is configured to operate to generate the signal that is at least indirectly indicative of the resistance of the at least one winding only at one or more times when an output signal provided at the output terminal does not indicate that one of the magnetic teeth is substantially aligned with the VRS.

14. An apparatus comprising the engine and system of claim 1, wherein the apparatus is either a lawn mower or a chain saw.

2. The system of claim I, wherein the electrical circuit further includes at least one additional component that is also electrically coupled to the first input terminal or to the second input terminal, wherein the at least one additional component includes a measurement system.

3. The system of claim 2, wherein the measurement system includes either an ohmmeter or an analog-to-digital converter (ADC).

4. The system of claim 2, wherein the measurement system is configured to sense one or both of a voltage applied to the first input terminal or a current flowing to or from the at least one winding.

15. A circuit for use in determining a temperature of a first portion of an internal combustion engine, the circuit comprising:

a variable reluctance sensor (VRS) including at least one winding and configured to generate a current upon being exposed to a changing magnetic flux due to a rotation of a wheel having magnetic teeth in proximity thereto;

a comparator having first and second input terminals and an output terminal, wherein the at least one winding is electrically coupled to the first input terminal, and wherein the comparator is configured to output an output signal at the output terminal that is indicative of whether a first voltage applied to the first input terminal is lesser or greater than a second voltage applied to the second input terminal,

wherein either the output signal or a further signal generated by the circuit is at least indirectly indicative of a resistance of the VRS that is in turn utilized directly or indirectly to determine the temperature of the first portion of the engine.

16. The circuit of claim 15, further comprising at least one additional component that is also electrically coupled to the first input terminal, wherein the at least one additional component includes either a measurement system component or a current source component, wherein the at least one additional component is configured to interact with the VRS during a time when the output signal provided at the output terminal is not at a level indicating that one of the magnetic teeth is substantially aligned with the VRS.

17. The circuit of claim 16, wherein the at least one additional component includes the measurement system component, and wherein the measurement system component is either an ohmmeter or an analog-to-digital converter (ADC).

18. The circuit of claim 16, wherein the at least one additional component includes the current source component, which is electrically coupled to the first input terminal by way of a switching component, wherein the temperature is determined at least in part by way of an interpolation operation, wherein the circuit also includes a voltage detection threshold device, wherein the second voltage applied to the second input terminal is provided by the voltage detection threshold device, and wherein the voltage detection threshold device is configured so as to be controllable so as to provide either of two different voltage levels as the second voltage.

19. A method of operation for determining a temperature of a first portion of an internal combustion engine, the method comprising:

rotating a wheel having a plurality of magnetic teeth that are spaced apart from one another around the wheel, so that at first times the magnetic teeth are substantially aligned with a variable reluctance sensor (VRS) and at second times none of the magnetic teeth are substantially aligned with the VRS but rather respective spaces between the magnetic teeth are substantially aligned with the VRS;

determining when one of the second times is occurring; and

detecting during one of the second times one or more of (a) a first voltage applied at a first terminal of a comparator electrically coupled to a winding of the VRS, (b) a first current provided to or from at least one winding of the VRS, and (c) an output signal from the comparator, so as to detect a signal that is at least indirectly indicative of a resistance of the at least one winding, wherein the signal that is at least indirectly indicative of the resistance is further at least indirectly indicative of the temperature.

20. A method of controlling an engine operational feature, wherein the method includes the method of claim 19 and further includes controlling one of a choking mechanism, a spark plug actuation, and a fuel injector actuation based at least in part upon the determined temperature.