Engine Temperature Estimation from Camshaft Angular Correction
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Solution Overview
Problem
Existing methods fail to accurately determine the engine temperature in internal combustion engines when the temperature sensor fails or provides incorrect data, necessitating degraded engine operation.
Innovation Solution
A method utilizing crankshaft and camshaft position sensors to calibrate and calculate engine temperature by determining corrective angular values based on engine speed and temperature correlations, allowing temperature estimation without a dedicated sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to measure engine temperature, then temperature measurement accuracy is improved, but system complexity and cost increase
Solution Approach 1:
The patent uses camshaft position sensor signals as an intermediary to indirectly determine engine temperature. Instead of directly measuring temperature with a temperature sensor, the system uses the angular position information from the camshaft position sensor to calculate temperature based on the relationship between camshaft position and engine operating conditions.
Solution Approach 2:
The patent replaces the thermal measurement system (temperature sensor) with a mechanical position measurement system (camshaft position sensor). The camshaft position sensor, which is already present for valve timing control, is repurposed to provide temperature information through signal processing and calculation algorithms.
2Reliability
If a temperature sensor is installed in the engine, then temperature monitoring capability is improved, but the number of components and system cost increase
Solution Approach 1:
The patent makes the camshaft position sensor multi-functional by using it for both its original purpose (valve timing control) and for temperature determination. This eliminates the need for a separate temperature sensor while maintaining temperature monitoring capability.
Solution Approach 2:
The system uses its existing components (camshaft position sensor and control unit) to provide temperature monitoring functionality without requiring additional dedicated temperature sensing components. The control unit processes the camshaft position signals to derive temperature information.
3Reliability
If the engine operates in degraded mode due to temperature sensor failure, then system reliability is maintained, but engine performance and emission compliance deteriorate
Solution Approach 1:
The patent prepares for temperature sensor failure by establishing an alternative temperature determination method using camshaft position signals. This backup system is ready to take over immediately when the temperature sensor fails, preventing the need for degraded operation mode.
Solution Approach 2:
The system continuously monitors camshaft position and uses this feedback to calculate engine temperature in real-time. This continuous feedback loop allows the control unit to maintain accurate temperature awareness and adjust engine parameters accordingly, even without a dedicated temperature sensor.
Data Source
AI summary
A method for determining an operating temperature of an engine, includes the following steps: calibrating the engine by determining an initial corrective angular value (CAV) in order to know the actual position of a camshaft; storing the initial CAV, a calibration temperature and a calibration speed; determining an operating CAV; determining a speed NRef and calculating an equivalent calibration CAV for a speed NRef and an equivalent operating CAV for NRef; calculating an angular difference AD between the equivalent calibration CAV and the equivalent operating CAV; determining the operating temperature on the basis of the difference AD, a CAV varying linearly with the temperature at constant speed according to a slope PTEMP, the temperature corresponding to the calibration temperature increased by the difference AD divided by the slope PTEMP.