Vehicle Engine Starting Control via Crank Angle Offset
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Solution Overview
Problem
Conventional starting control methods for vehicles fail to accurately synchronize engine control timing due to phase fixation issues with cam sensors, leading to engine start failures even when sensor signals appear normal, as they cannot distinguish between assembly errors and phase fixation abnormalities.
Innovation Solution
The proposed method involves determining engine RPM and normalcy of combustion-related parts, offsetting the recognized crank angle by 360 degrees when sensor signals are deemed normal, and restarting the engine based on this offset, with the Electronic Control Unit (ECU) diagnosing cam errors and deciding on limp home logic to maintain engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ECU determines that sensor signals from cam position sensor and crank position sensor are normal, then the engine control timing is determined based on these signals, but the sensor signal information may not coincide with the actual physical fastening state of the crank, leading to engine start failure
Solution Approach 1:
The ECU performs preliminary diagnostic checks during the starting period before normal operation begins. It checks whether the cam signal and crank signal coincide with each other during engine cranking, and if they do not coincide, the ECU determines that cam phase fixation has occurred and adjusts the injection timing accordingly before the engine actually starts, preventing start failure
Solution Approach 2:
The ECU continuously monitors the relationship between cam signal and crank signal during the starting period and uses this feedback to determine whether cam phase fixation has occurred. Based on this feedback, the ECU adjusts the injection timing to compensate for the phase fixation, ensuring reliable engine start even when sensor signals do not accurately reflect the physical crank position
2Measurement precision
If the ECU performs timing control during the starting period, then accurate engine control timing can be achieved, but the device complexity and control complexity increase
Solution Approach 1:
The ECU performs timing control and diagnostic checks during the starting period before normal operation begins. It checks whether the cam signal and crank signal coincide during engine cranking, and if they do not coincide, the ECU determines that cam phase fixation has occurred and adjusts the injection timing accordingly before the engine actually starts, preventing start failure
Solution Approach 2:
The system uses the existing cam position sensor and crank position sensor signals to perform self-diagnosis during the starting period. The ECU autonomously determines whether cam phase fixation has occurred by analyzing the relationship between the sensor signals, and automatically adjusts the injection timing without requiring additional sensors or complex external diagnostic equipment
Data Source
AI summary
A starting control method for a vehicle having an engine may include determining, by an ECU, whether engine RPM rises when the engine is started, determining whether combustion-related parts are normal, when the engine RPM does not rise over a starter RPM, determining whether a cam position sensor and a crank position sensor are normal, when it is determined that the combustion-related parts are normal, performing control to offset a recognized crank angle by 360 degrees, when it is determined that the cam position sensor and the crank position sensor are normal, and restarting the engine based on the offset crank angle.