Camshaft Position Determination Using Motor Controller Feedback
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Solution Overview
Problem
Existing engine control systems face challenges in accurately determining camshaft position during engine cranking, particularly in vehicles with variable cam timing, leading to inaccurate air/fuel charge estimation and increased emissions.
Innovation Solution
The method involves using an electric motor controller to indicate camshaft position during engine cranking, allowing for accurate determination of engine operating parameters, and switching to a camshaft sensor for position identification after cranking, ensuring precise air/fuel charge calculation and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cam position detection methods are used during engine cranking, then the system structure remains simple, but cam position measurement accuracy deteriorates leading to incorrect air/fuel charge estimation
Solution Approach 1:
The motor controller serving the electric motor for variable cam timing is made to perform dual functions: it not only controls the electric motor but also provides accurate cam position measurements during cranking. This eliminates the need for separate detection mechanisms during startup while maintaining measurement precision.
Solution Approach 2:
The motor controller utilizes its own operational data and control information to determine cam position during cranking without requiring external sensors or additional detection systems. The controller serves itself by leveraging its existing functionality to solve the measurement problem.
2Productivity
If default cam position is used during cranking, then the system operation remains simple, but engine start time increases and emissions increase due to inaccurate air/fuel charge
Solution Approach 1:
The motor controller provides real-time cam position feedback to the engine controller during cranking, enabling accurate determination of air charge and fuel injection timing. This feedback mechanism ensures optimal air/fuel mixture from the moment of cranking, reducing start time and emissions.
Solution Approach 2:
The system performs preliminary accurate cam position measurement and air/fuel charge calculation during the cranking phase itself, rather than relying on default values. This preliminary action ensures correct combustion parameters are established before the engine actually starts running.
3Measurement precision
If electric motor is used to drive camshaft during cranking, then cam position can be accurately indicated, but the system complexity increases compared to conventional detection methods
Solution Approach 1:
The motor controller is designed to perform multiple functions: controlling the electric motor that drives the camshaft and simultaneously providing accurate cam position measurements. This multi-functionality reduces the need for separate detection systems and minimizes overall system complexity while maintaining high measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate camshaft position indication during cranking, resulting in shorter engine start times and lower emissions by ensuring precise air/fuel charge determination, thereby improving engine control and reducing operational inefficiencies.
Implementation Method 1
the motor controller determines the motor position by decoding signals from three Hall Effect sensors coupled to a shaft of said motor
Data Source
AI summary
Various methods for determining camshaft position based on position indicated by an electric motor controller are provided. In one example, a method comprises: during cranking of an engine, driving a camshaft of the engine by an electric motor controlled by a motor controller which indicates motor position and position of the camshaft; determining one or more engine operating parameters for controlling the engine during the cranking by an engine controller from the indicated cam position; and after the cranking, identifying the cam position from a sensor coupled to the camshaft.