Hybrid Idle Stop Control Synchronizes CVT Clutch and Motor Timing
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Solution Overview
Problem
Hybrid electric vehicles experience shocks or shaking during idle stop mode due to mismatched times for engine off and motor torque removal, caused by uneven CVT clutch oil pressure drain and lack of deceleration compensation, leading to an unpleasant driving experience.
Innovation Solution
A method that synchronizes the CVT clutch oil pressure drain time, engine off time, and motor control time by generating a discrete signal based on CVT oil temperature and deceleration, allowing the CVT clutch to open before engine power is blocked and motor torque is applied, ensuring a linear stop without shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is stopped to improve fuel efficiency during idle stop mode, then fuel consumption is reduced, but vehicle shocks or shaking occur due to mismatched timing between engine off time and motor torque removal
Solution Approach 1:
The patent applies preliminary action by opening the CVT clutch in advance before stopping the engine. The control method calculates a clutch opening time based on oil temperature and deceleration, then opens the clutch at this calculated time point before the engine stop. This preliminary clutch opening ensures that the power transmission path is disconnected before engine stop, preventing the engine stop from directly causing vehicle shocks or shaking while still allowing the engine to be stopped for fuel efficiency.
2Speed
If the CVT clutch is opened quickly to enable engine stop, then idle stop mode is activated faster, but uneven oil pressure drain causes timing mismatch and vehicle instability
Solution Approach 1:
The patent applies dynamics by making the clutch opening timing adaptive rather than fixed. The control method dynamically calculates the optimal clutch opening time based on real-time oil temperature and deceleration conditions. Different oil temperatures and deceleration rates result in different calculated opening times, allowing the system to adapt to varying operational conditions and maintain vehicle stability while achieving relatively fast idle stop mode activation.
3Manufacturing precision
If additional sensors or actuators are added to precisely control the timing, then timing synchronization is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by using existing sensor data (oil temperature and deceleration information) that is already available in the hybrid vehicle system to calculate and determine the optimal clutch opening timing. The method does not require additional dedicated sensors or actuators for timing synchronization; instead, it utilizes the vehicle's existing operational parameters to self-determine the appropriate control timing, thereby achieving precise timing synchronization without increasing device complexity.
Data Source
AI summary
A method for controlling an idle stop mode in a hybrid electric vehicle is disclosed. The control method accords an oil pressure drain time that a continuously variable transmission clutch oil pressure is fully drained, a final off time of an engine, and a final control time of a motor when a hybrid electric vehicle enters an idle stop mode, thereby preventing a shock or shaking of the vehicle.