Engine Stop Control Using Dual Brake Pressure Thresholds
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Solution Overview
Problem
The existing engine control systems for automatic stop and restart deteriorate the controllability of anti-skid braking systems (ABS) when engine restarts occur under high brake pressure conditions, leading to potential safety issues due to battery voltage drops affecting motor operation.
Innovation Solution
An apparatus with a brake pressure detection unit, first and second determination units, and stop allowing/inhibiting units to manage engine stop and restart based on specific brake pressure thresholds, ensuring ABS controllability by inhibiting engine stop when high brake pressure is applied and preventing restart during ABS operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is stopped under IS control when the vehicle is decelerated, then fuel consumption is reduced, but the controllability of ABS control is deteriorated
Solution Approach 1:
The patent introduces two different brake pressure thresholds (first threshold and second threshold) to control engine stop conditions. When brake pressure exceeds the first threshold but remains below the second threshold, engine stop is permitted. When brake pressure exceeds the second threshold, engine stop is prohibited. This parameter-based differentiation resolves the contradiction by allowing fuel-saving engine stops during normal braking while preventing them during high-brake-pressure ABS operations.
Solution Approach 2:
The system continuously monitors brake pressure and uses this feedback to dynamically adjust engine control decisions. The brake pressure detection unit provides real-time information to the control unit, which then determines whether to permit or prohibit engine stop based on the current brake pressure level relative to the two thresholds. This feedback mechanism ensures that engine stop decisions are always aligned with current braking conditions.
2Productivity
If the engine is restarted based on engine restart request during ABS control, then battery voltage is lowered, but the operation of motor for ABS control is affected
Solution Approach 1:
The system proactively prevents engine restart during ABS control operations by detecting when brake pressure exceeds the second threshold. Before an engine restart request can negatively impact ABS control, the control unit prohibits the restart based on the high brake pressure detection. This preliminary protective action prevents the harmful effect of voltage drop on ABS motor operation.
3Device complexity
If a single brake pressure threshold is used for engine stop control, then the control logic is simple, but the system cannot prevent engine stop during high brake pressure conditions
Solution Approach 1:
The patent segments the brake pressure threshold into two distinct levels: a first threshold for permitting engine stop and a second threshold for prohibiting engine stop. This segmentation allows the system to differentiate between normal braking conditions (where engine stop is acceptable) and high-brake-pressure conditions (where engine stop must be prevented). The segmented threshold approach maintains relatively simple control logic while significantly improving reliability.
Data Source
AI summary
An apparatus for controlling automatic stop/restart of an engine, includes: an automatic-stop/restart-control-unit which stops/restarts the engine; a brake-pressure-detection-unit which detects brake pressure in a brake system and controls the brake pressure to perform anti-skid control; a first-determination-unit which determines whether the brake pressure is not less than a first-threshold; a second-determination-unit which determines whether the brake pressure is not less than a second-threshold larger than the-first threshold; a stop-allowing-unit which allows the automatic-stop/restart-control-unit to stop the engine while the engine operates, when the first-determination-unit determines that the brake pressure is not less than the first-threshold and the second-determination-unit determines that the brake pressure is less than the second-threshold; and a stop-inhibiting-unit which inhibits the automatic-stop/restart-control-unit from stopping the engine while the engine operates, when the-first-determination-unit determines that the brake pressure is less than the first-threshold and the second-determination-unit determines that the brake pressure is not less than the second-threshold.