Vehicle Control System Inhibits Engine Stop During Brake Mode Release
Solution Overview
Problem
Vehicles with idle-stop functions face unintentional movement due to loss of creep force when the engine stops, especially when the electric parking brake is not activated or malfunctioning, leading to reliability issues.
Innovation Solution
A vehicle control system that includes a brake control section, power control section, and inclination detection section, which inhibits the automatic stop of the drive power source when the automatic mode of the brake control section is released or if an abnormal condition is detected, ensuring the mechanical brake is engaged to prevent movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the automatic mode of the brake control section is released, then the driver has manual control over the brake system, but the vehicle may unintentionally move due to loss of creep force when the engine stops
Solution Approach 1:
The control section preemptively prevents automatic engine stop when the automatic brake mode is released, eliminating the potential hazard before it can occur. By checking the brake mode status and inhibiting automatic stop under inappropriate conditions, the system avoids the loss of creep force that would cause unintentional movement.
Solution Approach 2:
The control section continuously monitors the operation mode of the brake control section and uses this feedback information to determine whether automatic engine stop should be permitted. This closed-loop control ensures that automatic stop only occurs when the automatic brake mode is properly engaged, preventing safety issues.
2Use of energy by moving object
If the electric parking brake is not activated during idle stop, then energy consumption is reduced, but the vehicle may start to move unintentionally due to loss of creep force
Solution Approach 1:
The system preemptively prevents the combination of conditions that would lead to unintentional movement by inhibiting automatic engine stop when the automatic brake mode is released, regardless of energy consumption considerations. This ensures safety is prioritized over energy savings.
Solution Approach 2:
The system dynamically adjusts the automatic engine stop function based on the operational state of the brake control section. When the automatic mode is released, the system adapts by disabling automatic stop, while allowing it when the mode is properly engaged, optimizing both safety and energy efficiency.
3Ease of operation
If the automatic mode is released, then the driver maintains control over braking operations, but the brake booster stop may reduce braking force
Solution Approach 1:
The control section prevents automatic engine stop when the automatic brake mode is released, avoiding the scenario where reduced braking force from booster stop would compromise vehicle safety. This preemptive measure ensures adequate braking force is maintained when driver control is active.
Data Source
AI summary
A brake control section can select an automatic mode in which a mechanical brake is automatically transitioned from a released state to a braking state in response to the running condition of a vehicle. A diagnostic section outputs a fail signal when an abnormal condition of the brake control section is detected. A power control section automatically stops a drive power source of the vehicle when the running condition of the vehicle satisfies a predetermined condition for determining a vehicle stop. When the automatic mode of the brake control section is released or when the diagnostic section outputs a fail signal of the brake control section, the power control section is inhibited to automatically stop the drive power source, so that an unintentional movement of the vehicle caused by an inclination of the road surface and the automatic stop of the drive power source can be prevented.