Coast-Stop Control Device Gear Ratio Optimization
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Solution Overview
Problem
Existing coast-stop technologies fail to optimize gear change ratios during vehicle travel, leading to delays in acceleration restart and potential battery power shortages for maintaining hydraulic pressure in vehicles with automatic transmissions.
Innovation Solution
A coast-stop control device that includes an engine-stop-condition determination unit and a gear change control unit, which adjusts the gear change ratio before engine stop, utilizing a power transmission mechanism, an operating oil supply pump, and an electric oil pump to ensure appropriate gear positioning and hydraulic pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gear change control is performed regardless of the state of the preceding vehicle, then the transmission can downshift during coast-stop, but an appropriate gear change ratio cannot be attained if the vehicle comes close to the preceding vehicle or travels slowly
Solution Approach 1:
The patent changes the control parameters for gear shifting by introducing conditions based on vehicle speed and distance to preceding vehicle. The gear change control unit now considers multiple parameters (vehicle speed, inter-vehicle distance, acceleration request) to determine appropriate gear change ratios, rather than performing downshifts unconditionally during coast-stop.
2Loss of energy
If the coast-stop state continues for a long time, then fuel consumption is reduced, but a shortage of power of the battery for an electric oil pump may occur
Solution Approach 1:
The patent applies preliminary action by changing the gear ratio to a lower gear before the coast-stop ends or before battery power becomes insufficient. This prepares the transmission in advance to allow engine restart without requiring prolonged coast-stop, thus preventing battery power shortage while maintaining fuel efficiency benefits.
3Speed
If the gear change ratio is optimized for immediate acceleration restart, then acceleration response is improved, but the coast-stop duration is reduced due to battery power constraints
Solution Approach 1:
The patent makes the gear change control dynamic by continuously monitoring multiple conditions (vehicle speed, distance to preceding vehicle, coast-stop duration, battery state) and adjusting the gear change ratio accordingly. The system dynamically determines when to change gears based on the current operational context rather than using a fixed control strategy.
Data Source
AI summary
The purpose of the present invention is to provide a coast-stop control device that makes it possible to change gears to an appropriate gear change while traveling, before the engine is stopped. The present invention is a coast-stop control device for performing coast-stop control that automatically stops an engine while the vehicle is traveling, the coast-stop control device being characterized: in being provided with an engine stop condition-assessing means for assessing whether it is possible to stop the engine and a gear change control means for controlling the gear change ratio of a gear change mechanism; and in controlling the gear change mechanism to a prescribed gear change ratio when the engine stop condition-assessing means determines that an engine stop condition has been met.