Vehicle Engine Control Device for Stable Braking During Coast Stop
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Solution Overview
Problem
Existing engine automatic control devices may cause sudden deceleration when restarting the engine while driving, due to sudden multiplication of braking force resulting from negative pressure cessation after engine stop.
Innovation Solution
A vehicle engine automatic control device that stops the engine when the brake pedal operation exceeds a first threshold during coast drive and restarts it when negative pressure falls below a first threshold, preventing sudden deceleration by setting specific operation and negative pressure thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is stopped to improve mileage, then fuel consumption is reduced, but negative pressure ceases and causes sudden deceleration when the engine is re-started
Solution Approach 1:
The control device monitors negative pressure levels and re-starts the engine before negative pressure completely ceases. By taking preliminary action to re-start the engine when negative pressure falls below the threshold, the system prevents the harmful effect of sudden deceleration while maintaining the fuel-saving benefit of engine stop during coast drive.
Solution Approach 2:
The control device continuously monitors negative pressure levels and uses this feedback to determine the appropriate timing for engine re-start. The negative pressure threshold serves as a feedback signal that triggers the re-start condition, creating a closed-loop control system that balances fuel economy with braking stability.
2Speed
If the engine is re-started immediately after stop, then response time is improved, but negative pressure multiplication causes excessive braking force
Solution Approach 1:
The control device changes the operational parameters by introducing a negative pressure threshold condition for engine re-start. Instead of immediate re-start, the system waits until negative pressure falls below the threshold, thereby controlling the timing of re-start to prevent excessive braking force while maintaining adequate response speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents sudden increases in deceleration by ensuring the engine is restarted with sufficient negative pressure, maintaining stable braking force and improving mileage by optimizing engine stop and restart conditions.
Implementation Method 1
a negative pressure-based force multiplying means that multiplies the force with which the brake is operated by using negative pressure
Data Source
AI summary
A vehicle engine automatic control device has a brake pedal operation amount detecting unit that detects an amount of brake pedal operation by a driver, a negative pressure-based force multiplying unit that multiplies a force, with which a brake is operated, using an intake negative pressure of an engine, a negative pressure detecting unit that detects a negative pressure of the negative pressure-based force multiplying unit, and a coast stop control unit that stops the engine when the amount of brake pedal operation that is detected is equal to or greater than a first operation amount threshold during coast drive, and re-starts the engine when the negative pressure that is detected falls below a first negative pressure threshold after the engine stops.