Vehicle Cruise Control Engine Stop Logic
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Solution Overview
Problem
When automatic cruise control is stopped, the engine may start unexpectedly if the brake pedal is not depressed, causing driver unease and potentially leading to fuel wastage and unintended vehicle movement.
Innovation Solution
An electronic control unit that selectively executes and stops cruise control, keeps the engine stopped even when the brake pedal is not depressed, maintains braking force, and allows the engine to be started via the accelerator pedal, preventing malfunctions and ensuring the vehicle remains stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is stopped during automatic cruise control and the cruise control is stopped, the engine may start automatically since the brake pedal is not depressed, causing driver unease
Solution Approach 1:
The system dynamically adjusts engine start/stop behavior based on the operational state of cruise control. When cruise control is active, the engine remains stopped even if cruise control is subsequently deactivated, creating a dynamic transition state that prevents automatic restart. This dynamic behavior resolves the contradiction by maintaining fuel efficiency while eliminating unexpected engine starts that cause driver unease.
Solution Approach 2:
The system changes the parameter of engine restart permission based on the cruise control execution state. A flag or condition is set when cruise control is executed, which modifies the restart logic to prevent automatic engine start even when brake pedal conditions would normally permit it. This parameter change ensures the engine only restarts when the driver explicitly intends to do so, resolving the reliability issue while preserving fuel savings.
2Loss of energy
If the engine is kept stopped after stopping cruise control during deceleration, fuel consumption is reduced but the vehicle may move backward
Solution Approach 1:
The system introduces an intermediary braking mechanism that operates independently of engine status. When the engine is kept stopped during deceleration under cruise control, a braking force generation unit provides necessary braking force to prevent backward movement. This intermediary braking system resolves the contradiction by maintaining fuel efficiency through engine stoppage while ensuring vehicle stability through active braking intervention.
Solution Approach 2:
The braking system serves itself by automatically generating braking force when needed, without requiring engine operation. The braking force generation unit detects when engine stoppage might cause backward movement and autonomously applies braking force to prevent it, ensuring the vehicle remains stable while the engine remains stopped for fuel efficiency.
3Loss of energy
If the engine is kept stopped during deceleration under cruise control, fuel wastage is reduced but driver control flexibility is limited
Solution Approach 1:
The system implements feedback through the accelerator pedal detection mechanism. When the accelerator pedal is depressed, the system receives feedback indicating driver intent to accelerate, which triggers engine restart. This feedback loop resolves the contradiction by maintaining fuel efficiency through extended engine stoppage while preserving driver control flexibility, as the driver can still initiate engine restart through natural accelerator pedal operation.
Solution Approach 2:
The engine restart function serves itself automatically when the driver depresses the accelerator pedal. The system monitors accelerator pedal position and autonomously restarts the engine when acceleration is requested, without requiring separate ignition or start commands. This self-service mechanism maintains fuel efficiency while ensuring full driver control flexibility is preserved through intuitive accelerator-based engine restart.
Data Source
AI summary
A control system for a vehicle including a brake pedal operable by a driver and an engine includes an electronic control unit. The electronic control unit is configured to: (a) execute cruise control, the cruise control selectively executed and stopped through an operation of the driver, (b) stop the engine upon depression of the brake pedal, when the cruise control is stopped, (c) stop the engine while the vehicle is being decelerated or stopped, even when the brake pedal is not depressed, when the cruise control is executed, and (d) keep the engine stopped even when the operation to stop the cruise control is performed, after the engine is stopped and the cruise control is executed.