Dynamic Engine Start Threshold for Vehicle Speed
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Solution Overview
Problem
Conventional vehicle engine automatic control devices restart the engine against the driver's intention when driving at reduced speeds, leading to inefficient mileage due to fixed engine start determination thresholds regardless of vehicle speed.
Innovation Solution
The engine start determination threshold is set smaller as the vehicle speed lowers, with separate thresholds for decreasing and increasing brake pedal operations to better align with the driver's intentions and improve mileage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the engine start determination threshold is set fixed regardless of vehicle speed, then the control logic is simple, but the engine may be re-started against the driver's intention when driving at reduced speed
Solution Approach 1:
The engine start determination threshold is changed from a fixed value to a dynamic value that varies with vehicle speed. The control unit adjusts the threshold based on the detected vehicle speed, making the threshold smaller as vehicle speed decreases. This dynamic adjustment prevents premature engine restarts at low speeds while maintaining simple control logic.
Solution Approach 2:
The patent changes the parameter of the engine start determination threshold based on the vehicle speed parameter. By establishing a relationship where the threshold decreases as vehicle speed decreases, the system accurately reflects driver intent across different operating conditions without requiring complex control structures.
2Ease of operation
If the engine start determination threshold is set fixed regardless of vehicle speed, then the control system is easy to operate, but mileage cannot be improved sufficiently
Solution Approach 1:
The system dynamically adjusts the engine start determination threshold according to vehicle speed, allowing the engine to remain stopped longer at low speeds where restarts would be unnecessary. This extends the engine stop duration and reduces fuel consumption while maintaining easy automated operation.
Solution Approach 2:
The patent converts the potential harm of premature engine restarts at low speeds into a benefit by using the vehicle speed information to suppress unnecessary restarts. This transforms what would be a control error into an opportunity for fuel savings and improved mileage efficiency.
3Loss of energy
If the engine start determination threshold is set smaller as vehicle speed lowers, then mileage is improved, but the control logic becomes more complex
Solution Approach 1:
The patent implements a straightforward parameter change relationship where the engine start determination threshold is directly linked to vehicle speed. This simple functional relationship achieves fuel savings without requiring complex control logic, as the threshold automatically adjusts based on the detected speed parameter.
Data Source
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AI summary
A brake operation amount detecting means that is configured to detect the amount of brake operation by the driver, an engine stopping/re-starting means (engine control unit), during coast drive, that is configured to stop the engine based on the amount of brake operation that is detected, and, after the engine stops, re-start the engine when the amount of brake operation that is detected falls below the first threshold, and a first threshold setting means that is configured to set the first threshold smaller as the vehicle speed VSP lowers, are provided.