Method for estimating the temperature in an internal combustion engine
View Patent ↗A method is provided for estimating the temperature in an internal combustion engine. The method includes, but is not limited to the steps of providing a sensor resistor (RTD) in the internal combustion engine, the sensor resistor (RTD) having a predetermined resistance-temperature characteristic, measuring a sensor voltage (V RTD ) across the sensor resistor (RTD), calculating a resistance value of the sensor resistor (RTD) based on the sensor voltage (V RTD ) and estimating the temperature using the resistance value and the resistance-temperature characteristic. The method further comprises the steps of connecting, in series to the sensor resistor (RTD), a first branch of a current mirror arrangement, connecting a reference resistor (R 0 ) in series to a second branch of the current mirror arrangement, measuring a reference voltage (V 0 ) across the reference resistor (R 0 ) and calculating the resistance value of the sensor resistor (RTD) based on the sensor voltage (V RTD ) and the reference voltage (V 0 ).
1. A circuit for estimating a temperature in an internal combustion engine, the circuit comprising:
a sensor resistor (RTD) having a predetermined resistance-temperature characteristic;
a computer (M) connected in parallel to the sensor resistor (RTD) and arranged to:
measure a sensor voltage (V RTD ) across said sensor resistor (RTD);
calculate a resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ); and
estimate a temperature value using said resistance value and the predetermined resistance-temperature characteristic of the sensor resistor (RTD);
a first branch of a current mirror arrangement connected in series to said sensor resistor (RTD);
a reference resistor (R 0 ) connected in series to a second branch of the current mirror arrangement,
wherein the computer (M) is connected in parallel to the reference resistor (R 0 ) and being arranged to:
measure a reference voltage (V 0 ) across said reference resistor (R 0 ); and
calculate the resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ) and said reference voltage (V 0 ); and
an analogue to digital converter (ADC) in parallel to the sensor resistor (RTD) and the reference resistor (R 0 ) configured to provide digital values representative of the sensor voltage (V RTD ) and the reference voltage (V 0 ).
2. The circuit of claim 1 , wherein the current mirror arrangement is configured to supply a mirrored current (I RTD ) to the sensor resistor (RTD), said mirrored current (I RTD ) flowing through the first branch of the current mirror arrangement.
3. The circuit of claim 1 , wherein the current mirror arrangement is configured to supply a reference current (I 0 ) to the reference resistor (R 0 ), said reference current (I 0 ) flowing through said second branch of the current mirror arrangement.
4. The circuit of claim 2 , wherein the current mirror arrangement is configured to supply a reference current (I 0 ) to the reference resistor (R 0 ), said reference current (I 0 ) flowing through said second branch of the current mirror arrangement.
5. The circuit of claim 4 , wherein the computer (M) is configured to calculate the resistance value of the sensor resistor (RTD) according to:
RTD
=
R
0
V
RTD
V
0
where RTD is a value representative of the resistance value of the sensor resistor (RTD).
6. A circuit for estimating a temperature in an internal combustion engine, the circuit comprising:
a sensor resistor (RTD) having a predetermined resistance-temperature characteristic;
a computer (M) connected in parallel to the sensor resistor (RTD) and arranged to:
measure a sensor voltage (V RTD ) across said sensor resistor (RTD);
calculate a resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ); and
estimate a temperature value using said resistance value and the predetermined resistance-temperature characteristic of the sensor resistor (RTD);
a first branch of a current mirror arrangement connected in series to said sensor resistor (RTD); and
a reference resistor (R 0 ) connected in series to a second branch of the current mirror arrangement,
wherein the computer (M) is connected in parallel to the reference resistor (R 0 ) and being arranged to:
measure a reference voltage (V 0 ) across said reference resistor (R 0 ); and
calculate the resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ) and said reference voltage (V 0 ),
wherein the computer (M) is configured to calculate the resistance value of the sensor resistor (RTD) according to:
RTD
=
R
0
V
RTD
V
0
where RTD is a value representative of the resistance value of the sensor resistor (RTD).
7. The circuit of claim 6 , further comprising an analogue to digital converter (ADC) in parallel to the sensor resistor (RTD) and the reference resistor (R 0 ) configured to provide digital values representative of the sensor voltage (V RTD ) and the reference voltage (V 0 ).