Engine Stop Control via Brake Pressure Thresholds
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Solution Overview
Problem
Existing idle stop control systems do not allow engine automatic stop before the vehicle reaches a predetermined speed, limiting fuel consumption benefits when a driver wishes to stop the engine in traffic jams.
Innovation Solution
An engine control apparatus that detects increased brake operation and inhibits engine automatic stop until a predetermined speed is exceeded, allowing the engine to be stopped based on the driver's intent by releasing inhibition when the brake pressure exceeds a second threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine automatic stop is inhibited until the vehicle speed exceeds a predetermined speed, then frequent starts and stops are prevented in traffic jams, but the driver's intent to stop the engine earlier cannot be fulfilled
Solution Approach 1:
The system monitors brake operation amount as feedback from the driver's action, and uses this feedback to determine when to release the engine automatic stop inhibition, thereby adapting to the driver's intent while maintaining the speed-based safety constraint
Solution Approach 2:
The inhibition release condition is made dynamic by combining a fixed speed threshold with a variable brake operation threshold, allowing the system to adapt between maintaining strict speed-based inhibition and responding to driver intent based on real-time brake pressure conditions
2Loss of energy
If the engine automatic stop is allowed at low speeds without speed threshold restriction, then fuel consumption is reduced by stopping the engine earlier, but frequent starts and stops occur in traffic jams
Solution Approach 1:
The system changes the operational parameters by introducing a dual-threshold mechanism (speed threshold and brake operation threshold) that dynamically adjusts when engine automatic stop is permitted, balancing energy savings with operational stability
Solution Approach 2:
The system performs preliminary inhibition of engine automatic stop at low speeds until the speed threshold is exceeded, preventing premature stopping, but allows the function to activate when brake operation indicates driver intent, achieving early stop when appropriate
3Adaptability or versatility
If the brake operation threshold is set low, then the engine automatic stop is released frequently responding to minor brake inputs, but false activation occurs during normal braking
Solution Approach 1:
The system uses parameter changes by establishing a specific threshold relationship where the brake operation threshold is set higher than normal braking pressure but lower than firm braking pressure, and combines this with the speed threshold condition to filter false activations
Solution Approach 2:
The system applies partial action by requiring both conditions (speed threshold and brake operation threshold) to be satisfied simultaneously, rather than responding to either condition alone, thereby reducing false activation while maintaining responsiveness
Data Source
AI summary
An engine control apparatus capable of performing engine automatic stop includes an engine automatic stop inhibition means configured to inhibit the engine automatic stop after engine restart conditions are satisfied and the engine is restarted until a vehicle speed exceeds a predetermined speed, a brake operation detection means configured to detect a presence of increase of the amount of a brake operation in a state of the brake operation being performed after the vehicle has been stopped, and an engine stop control means configured to release inhibition of the engine automatic stop to allow the engine to be automatically stopped, if the brake operation detection means detects presence of increase of the amount of the brake operation while the engine automatic stop is inhibited by the engine automatic stop inhibition means.