Brake-by-wire Control for Creep Force Management
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Solution Overview
Problem
The non-zero vehicle speed idling stop control system fails to effectively restrain vehicles from moving forward due to creep forces after engine restart during traveling, as drivers struggle to apply sufficient brake pedal pressure, leading to safety and fuel economy issues.
Innovation Solution
A vehicle system with a brake-by-wire mechanism that automatically increases braking force from a detected brake pedal manipulation, maintaining it until the engine speed reaches a maximum after restart, to prevent unintended movement and ensure smooth starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-zero vehicle speed idling stop control is implemented to improve fuel economy, then fuel consumption is reduced, but the vehicle may start moving forwardly due to creep force after engine restart
Solution Approach 1:
The control device applies preliminary anti-action by detecting brake pedal manipulation and automatically increasing braking force before the engine restarts and generates creep force. This preventive measure counteracts the potential forward movement by establishing a restraining braking force in advance, resolving the contradiction between fuel economy improvement and vehicle stability maintenance.
Solution Approach 2:
The system implements feedback control by continuously monitoring brake pedal manipulation signals and engine operation states. When the brake pedal is detected as manipulated during idling stop control, the control device responds by increasing braking force, and when the brake pedal is released, it reduces braking force. This closed-loop feedback mechanism ensures vehicle stability while maintaining fuel economy benefits.
2Reliability
If brake fluid pressure is increased to prevent vehicle movement from creep force, then vehicle stability is improved, but the vehicle may not start moving smoothly after engine restart
Solution Approach 1:
The braking force control is made dynamic rather than static. The control device adjusts braking force based on real-time detection of brake pedal manipulation and engine operation states. Braking force is increased only when the brake pedal is manipulated during idling stop control, and reduced when the brake pedal is released or engine restart is detected. This dynamic adjustment prevents unintended movement while ensuring smooth vehicle starting, resolving the contradiction between stability and ease of operation.
3Use of energy by moving object
If automatic engine stop during traveling is implemented, then fuel economy is improved, but driver's intention to move the vehicle may be ignored due to insufficient brake pedal depression
Solution Approach 1:
The control device provides self-service by automatically detecting brake pedal manipulation and adjusting braking force without requiring the driver to manually apply sufficient brake pressure. The system monitors the brake pedal manipulation signal and autonomously increases braking force when detected during idling stop control, then reduces it when the brake pedal is released. This eliminates the need for the driver to overcome the idling stop control system manually, improving both fuel economy and vehicle responsiveness to driver intent.
Data Source
AI summary
A vehicle system comprises a brake system comprising a brake pedal and a braking mechanism configured to apply a braking force to a vehicle, and a vehicle control unit operable to automatically stop an engine when the vehicle is decelerated to a given vehicle speed or less during traveling. When it is detected that the brake pedal is manipulated and the vehicle is stopped after automatically stopping the engine, the vehicle control unit is operable to control the braking mechanism to increase the braking force from a current value according to a manipulation amount of the brake pedal up to a given value.