Hybrid Vehicle Ignition Timing Control for Engine Speed Stability
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Solution Overview
Problem
In hybrid vehicles, engine load variations during startup can lead to sudden increases in engine speed, causing fuel efficiency degradation, increased noise, and vibration, due to uncontrolled engine revolution speed by the rotating electric machine.
Innovation Solution
A control device adjusts the ignition timing of the engine based on whether the engine revolution speed is controlled by the rotating electric machine, setting a more retarding ignition timing initially and restoring it to a steady operation timing at a predetermined rate, depending on the control status, to manage engine load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the ignition timing is set to suppress sudden increase of engine revolution speed in low load state, then the engine speed stability is improved, but knocking may occur due to insufficient engine torque when load is relatively high
Solution Approach 1:
The ignition timing is made dynamic rather than fixed, adjusting between advance and retard positions based on real-time engine operating conditions. The ECU monitors engine speed, load, and other parameters to determine optimal ignition timing, allowing the system to suppress speed fluctuations when needed while ensuring sufficient torque when load increases
Solution Approach 2:
The ignition timing parameter is changed based on engine operating conditions. When engine speed fluctuates excessively, the timing is retarded to suppress the fluctuation. When load increases and torque is needed, the timing is advanced to ensure sufficient engine output. This parameter adjustment resolves the contradiction between speed stability and torque sufficiency
2Device complexity
If the engine revolution speed is not controlled by the rotating electric machine during startup, then the device complexity is reduced, but the engine speed may suddenly increase causing fuel efficiency degradation and increased noise
Solution Approach 1:
The engine control system uses its own ignition timing mechanism to regulate engine speed during startup, rather than relying on the rotating electric machine. By adjusting ignition timing between advance and retard positions, the system achieves speed control functionality using existing engine components, avoiding additional complexity while preventing fuel efficiency degradation from uncontrolled speed increases
3Power
If the engine is restarted frequently during running based on torque requirements and SOC state, then the power availability is improved, but the fuel efficiency may degrade due to repeated engine load variations
Solution Approach 1:
The ECU continuously monitors engine operating parameters including speed, load, and torque requirements, using this feedback to determine optimal ignition timing. When the engine is restarted or load conditions change, the system adjusts ignition timing to prevent excessive speed fluctuations, thereby maintaining power availability while minimizing fuel efficiency degradation from repeated load variations
Data Source
AI summary
A hybrid vehicle includes an engine, a motor generator configured to control the revolution speed of the engine, and an ECU configured to control ignition timing of the engine. The ECU modifies, in the case where the revolution speed of the engine is not controlled by the motor generator, the ignition timing for startup of the engine to a further timing retarding side, as compared to the case where the revolution speed of the engine is controlled by the motor generator.