Engine Output Control for CVT Shift Response and Belt-Slip Prevention
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Solution Overview
Problem
Existing engine output control systems face challenges in simultaneously achieving transient shift response improvement and steady belt-slip prevention due to limitations in responsiveness and stability, particularly in automatic transmissions like CVTs, where throttle opening control has low responsiveness and ignition timing control has durability and emission concerns.
Innovation Solution
An engine output control apparatus that selectively uses multiple control systems, such as throttle opening control for steady-state stability and ignition timing control for transient response, based on operating conditions to prevent excessive torque input and enhance shift speed, thereby reconciling the need for both belt-slip prevention and shift response improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If throttle opening control is used for engine output limiting, then steady-state stability is improved, but transient response is deteriorated
Solution Approach 1:
The system dynamically switches between throttle opening control and ignition timing control based on operating conditions. During transient states (acceleration, deceleration, gear shifts), ignition timing control is activated for fast response. During steady-state operation, throttle opening control is used for stability. This dynamic adaptation resolves the contradiction by applying the appropriate control mode at the appropriate time.
Solution Approach 2:
The control system changes the operating parameters of the engine by adjusting either throttle opening or ignition timing depending on the situation. The ECU monitors engine load, speed, and other parameters to determine which control parameter to modify, enabling the system to achieve both fast transient response and stable steady-state operation through parameter selection.
2Speed
If ignition timing control is used for fast torque reduction, then transient response is improved, but catalyst durability and emission performance are deteriorated
Solution Approach 1:
The system applies ignition timing control periodically or temporarily only during transient events (gear shifts, acceleration changes) rather than continuously. The ECU activates ignition timing adjustment only when transient conditions are detected, then switches back to throttle control for steady-state operation, thereby limiting the cumulative impact on catalyst temperature while maintaining fast response when needed.
Solution Approach 2:
The control strategy dynamically selects between ignition timing control and throttle opening control based on real-time operating conditions. Ignition timing control is applied only during transient states where fast response is critical, while throttle control handles steady-state conditions, thus protecting the catalyst from prolonged exposure to suboptimal combustion conditions while maintaining transient performance.
3Device complexity
If single control system is used for both transient and steady-state control, then device complexity is reduced, but control performance is deteriorated
Solution Approach 1:
The ECU serves multiple functions by implementing both throttle opening control and ignition timing control algorithms within a single control unit. The ECU monitors various engine parameters and selectively applies the appropriate control strategy based on operating conditions, achieving multi-functionality without requiring separate physical control systems for transient and steady-state operations.
Solution Approach 2:
The patent combines throttle opening control and ignition timing control into a unified control system managed by a single ECU. The control algorithms for both methods are integrated, and the ECU selectively activates the appropriate control mode based on sensor inputs, merging the benefits of both control strategies while avoiding the complexity of completely separate control systems.
Data Source
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Figure 3A~3G
AI summary
In an engine output control apparatus of a power train employing an engine and an automatic transmission, capable of executing engine output control for excessive torque input prevention engine torque limiting action and for a shift speed control of the transmission, at least two different kinds of engine output control systems having control characteristics differing from each other, are provided. A controller selectively uses these engine output control systems depending on a power-train operating condition, such that a first one of the engine output control systems having a superior transient response is used for the engine output control for shift response control during shifting, and that a second one of the engine output control systems having a superior steady-state stability is used for the engine output control for excessive torque input prevention engine torque limiting action during non-shifting.