Air-Cooled Engine Temperature Estimation Without Cylinder Head Sensor
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Solution Overview
Problem
Air-cooled internal combustion engines without a cylinder head temperature sensor require an alternative method for temperature control, especially during cold-start and warm-up phases, as traditional sensors cannot be installed in all configurations.
Innovation Solution
An electronic control unit method that determines engine temperature by setting initial values based on admitted-air temperature and iteratively adjusts filtering coefficients and setpoints using stored maps related to engine operational states, rotational speed, and load, allowing for temperature estimation without a dedicated sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is installed on the cylinder head to measure engine temperature, then temperature measurement accuracy is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent replaces the mechanical/physical temperature sensor with an electronic control algorithm that calculates engine temperature based on admitted air temperature and filtering coefficients. This substitution eliminates the need for physical sensor installation on the cylinder head while maintaining temperature monitoring capability through computational methods.
Solution Approach 2:
The patent introduces an intermediary approach by using admitted air temperature as a proxy indicator for engine temperature. Instead of directly measuring cylinder head temperature, the system uses the temperature of air entering the engine combined with filtering coefficients to estimate engine temperature, thereby avoiding direct sensor installation on the cylinder head.
2Measurement precision
If a temperature sensor is installed on the cylinder head, then temperature control accuracy is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent extracts the temperature sensing function from the physical cylinder head by removing the requirement for sensor installation. The temperature measurement capability is extracted and relocated to the electronic control unit, where it is calculated based on admitted air temperature and filtering coefficients, thereby eliminating the need for mechanical modifications to the engine structure.
Solution Approach 2:
The patent replaces the mechanical sensor installation approach with an electronic computational approach. The control unit calculates engine temperature using algorithms that process admitted air temperature data and filtering coefficients, substituting the need for physical sensor integration into the engine manufacturing process.
3Device complexity
If admitted-air temperature is used as the initial engine temperature value, then device complexity is reduced, but temperature measurement precision deteriorates
Solution Approach 1:
The patent implements feedback mechanisms through iterative filtering processes. The control unit continuously refines the engine temperature estimate by applying filtering coefficients that are updated based on operational conditions. This feedback loop allows the system to progressively improve temperature measurement accuracy starting from the initial admitted-air temperature value without requiring complex sensor hardware.
Solution Approach 2:
The patent changes the parameter used for temperature estimation from a static initial value to a dynamically updated value. The filtering coefficient is continuously adjusted based on engine operational state, allowing the temperature calculation to adapt to changing conditions and improve precision over time while maintaining relatively simple control architecture.
Data Source
AI summary
A method for controlling an air-cooled internal combustion engine (ICE) of a motor vehicle controlled by an electronic control unit, includes: activating the electronic control unit; zeroing stored values of temperature of the ICE and the filtered filtering coefficient; in one iteration, —determining whether the ICE is operating, determining a filtering coefficient and a temperature setpoint, —determining a filtered filtering coefficient based on the filtering coefficient and the stored filtered filtering coefficient value, —determining temperature of the ICE according to the coefficient, temperature setpoint and stored temperature of the ICE, —determining whether the ICE is moving and whether the difference between engine temperature and admitted air temperature is below a threshold, ⋅ if not, storing the filtered filtering coefficient and the temperature of the ICE, then beginning a new iteration, and ⋅ if so, transmitting a signal authorizing the shutdown of the electronic control unit.