Engine Start Control Device Torque Synchronization
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Solution Overview
Problem
Conventional engine start control devices face challenges in controlling torque and rotational speed variations during engine restart, leading to potential engine stalling and decreased controllability, especially when transitioning from motor-driven to fuel combustion modes without precise torque detection.
Innovation Solution
An engine start control device with three control modes: motoring, fuel combustion, and combined motor/engine control, where the transition from motoring to fuel combustion is managed through a motor/engine combined control state, synchronizing with the crank angle of the first fuel combustion to optimize torque control and reduce motor torque accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque detection sensors (internal pressure sensor or torque sensor) are installed to detect engine torque precisely, then torque control precision is improved, but vehicle cost increases
Solution Approach 1:
The patent creates a virtual copy of torque detection by calculating engine torque from the relationship between engine rotational speed and motor rotational speed, rather than using physical sensors. This computational model replicates the function of expensive torque sensors through software algorithms, eliminating the need for additional hardware while achieving precise torque control during engine restart
Solution Approach 2:
The patent replaces the mechanical sensor-based torque detection system with an electronic calculation system. By substituting physical measurement devices with computational methods that analyze rotational speed relationships, the system achieves the same control precision without the cost and complexity of additional sensors
2Device complexity
If the engine transitions directly from motoring control state to fuel combustion control state, then control simplicity is improved, but engine stalling risk increases due to sudden torque fluctuation
Solution Approach 1:
The patent divides the engine restart process into three distinct control stages: motoring control state (motor provides all torque), motor/engine combined control state (motor and engine share torque), and fuel combustion control state (engine provides all torque). This segmentation allows gradual transition and smooth torque handover, preventing engine stalling while maintaining manageable control complexity through clear state definitions
Solution Approach 2:
The patent implements preliminary action by introducing the motor/engine combined control state as a preparatory phase before full fuel combustion control. During this intermediate state, the motor gradually reduces its torque contribution while the engine gradually increases its torque output, allowing the engine to stabilize before complete motor disengagement. This preliminary transition phase prevents sudden torque fluctuations that could cause stalling
3Speed
If motor torque is reduced immediately when fuel combustion torque is detected, then torque control responsiveness is improved, but control delay occurs due to one control cycle detection lag
Solution Approach 1:
The patent applies preliminary action by proactively reducing motor torque based on predicted combustion timing rather than waiting for actual torque detection. The control system calculates when combustion will occur and begins reducing motor torque in advance, eliminating the one-control-cycle delay that would otherwise occur while maintaining rapid responsiveness to combustion events
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 precise control of torque and rotational speed variations without delays, improving engine restart stability and reducing the risk of stalling by aligning motor and engine torque adjustments with fuel combustion timing.
Implementation Method 1
a motor which causes the engine to rotate
Implementation Method 2
the engine enters a restart state in which the rotational speed of the engine rises. Then, when predetermined conditions are satisfied, fuel injection is restarted
Data Source
AI summary
A start control device for an engine includes an engine control unit, a motor control unit, and a control unit which controls the engine control unit and the motor control unit, wherein the control unit, when transferring an engine restart control mode from a motoring control state to a fuel combustion control state, executes the transfer via a motor/engine combined control state, and sets the timing of transferring from the motoring control state to the motor/engine combined control state, to a timing at which a crank angle of a cylinder where fuel is combusted first after starting fuel injection reaches a crank angle at which it is estimated that torque is generated by the first combustion of fuel in the cylinder.