Engine Stop/Start Throttle Control for Vibration Suppression
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Solution Overview
Problem
Existing engine stop/start control systems face challenges in securing startability while minimizing vibration when an engine is automatically stopped and restarted, particularly due to insufficient air supply and increased compression reactive force during idling stop conditions.
Innovation Solution
An engine stop/start control apparatus that adjusts the throttle valve opening degree to be larger than the idle state during engine stop, applies counter torque using a rotating electrical machine to shorten the engine speed drop period through the resonance range, and optimizes the rotation drop control based on predetermined speed ranges to suppress vibration and ensure restartability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the throttle valve is opened to introduce air before rotation of an engine output shaft is stopped, then air supply for restart is improved, but compression reactive force increases which results in increasing vibration
Solution Approach 1:
The throttle valve is opened in advance before the engine output shaft stops rotating to secure air supply for restart. This preliminary action ensures that sufficient air is available in the intake system when the engine needs to restart, while the control strategy manages the timing to minimize vibration effects during the deceleration phase.
Solution Approach 2:
The throttle valve opening degree is dynamically adjusted based on the engine's rotational state. By making the opening degree larger than in the idle rotating state during the rotation drop period, the system optimizes air supply while managing compression reactive force to suppress vibration during the transition to stop and restart.
2Speed
If the throttle valve is closed to stop the engine, then engine stop is achieved, but air supply becomes insufficient when the engine restarts
Solution Approach 1:
The throttle valve is opened in advance before the engine output shaft stops rotating to secure air supply for restart. This ensures that the intake system has sufficient air available when the engine needs to restart, preventing air supply insufficiency that would occur with complete closure.
Solution Approach 2:
The throttle valve opening degree parameter is changed from a closed or idle state to a larger opening degree during the rotation drop period. This parameter change ensures adequate air supply for restart while the engine speed is decreasing, resolving the contradiction between stopping the engine and maintaining air supply.
3Quantity of substance
If the engine speed passes through the resonance range slowly, then air supply is maintained, but vibration increases in the resonance range
Solution Approach 1:
The engine speed is controlled to pass through the resonance range more quickly by adjusting the throttle valve opening degree. This rushing through strategy minimizes the time spent in the resonance range, thereby suppressing vibration while still maintaining adequate air supply for the restart process.
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
The solution secures a sufficient air supply for engine restarts, reduces vibration by shortening the time in the resonance range, and enhances startability and power efficiency by using existing vehicle components without additional devices.
Implementation Method 1
the rotation drop control section applies counter torque to the engine output shaft by the auxiliary device as the rotation drop processing
Data Source
AI summary
An ECU makes an opening degree of a throttle valve larger than an opening degree in an idle rotating state of an engine in a rotation drop period during which engine speed drops to zero after combustion of the engine is stopped. Further, the ECU determines that the engine speed is within a predetermined rotation speed range including at least a resonance range of the engine in the rotation drop period, and, in the case where it is determined that the engine speed is within the predetermined rotation speed range, the ECU performs rotation drop processing of temporarily increasing a drop rate of the engine speed.