Engine Stop Delay Control Throttle Valve Adjustment
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Solution Overview
Problem
Conventional variable valve actuation mechanisms in internal combustion engines face challenges in maintaining optimal valve characteristics during engine stop and restart, leading to potential startability issues and safety concerns during delay control periods.
Innovation Solution
A control apparatus that includes delay means to extend the engine stop request period, changing means to adjust valve characteristics for starting conditions, and limiting means to reduce engine control amounts during delay control, along with determination and inhibiting means to assess urgent stop requests and prevent accidental engine power increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delay control is performed to extend the period from engine stop request to actual engine stop, then valve characteristics can be changed to suitable starting characteristics, but the risk of accidental engine manipulation and safety hazards increases
Solution Approach 1:
The throttle valve opening degree is dynamically adjusted based on the execution state of delay control. During delay control execution, the opening degree is limited to a predetermined degree or less, while during non-execution, it can be set to a larger degree corresponding to accelerator pedal depression. This dynamic adjustment resolves the contradiction by adapting the throttle valve behavior to the specific operational phase.
Solution Approach 2:
The control apparatus changes the parameter of throttle valve opening degree based on the delay control execution state. By setting the opening degree to a predetermined degree or less during delay control, the system modifies the engine's response to accelerator pedal depression, preventing accidental power increases while maintaining the ability to achieve suitable valve characteristics for starting.
2Ease of operation
If the throttle valve opening degree is set according to accelerator pedal depression degree during delay control, then engine responsiveness is maintained, but engine safety is compromised due to potential accidental power increases
Solution Approach 1:
The system dynamically changes the relationship between accelerator pedal depression and throttle valve opening degree based on delay control execution. During delay control, the throttle valve opening is decoupled from accelerator pedal depression and limited to a predetermined degree, eliminating the harmful effect of accidental manipulation while maintaining operational simplicity.
Solution Approach 2:
The control apparatus applies different control strategies to the throttle valve based on the operational phase. During delay control execution, a restrictive opening degree is applied locally to prevent power increases, while during non-execution, the normal responsive control is restored. This local differentiation resolves the contradiction between responsiveness and safety.
Data Source
AI summary
An electronic control unit 9 performs a delay control for extending the period from when an engine stop request is made to when the engine is actually stopped. During non-execution of the delay control, the electronic control unit 9 adjusts the opening degree of a throttle valve 38 according to an accelerator pedal depression degree. During the execution of the delay control, the electronic control unit 9 adjusts the opening degree of a throttle valve 38 such that the opening degree becomes less than the opening degree during the non-execution of the delay control.