Hybrid Vehicle Drive Mode Shift Control via Clutch Torque Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid vehicles face challenges in shifting drive modes from single-motor to dual-motor mode efficiently due to potential damage to stopper devices from excessive torque and the need for space-consuming torque limiters, which can slow down acceleration responses.
Innovation Solution
A control system that uses an engagement device to interrupt torque transmission and a stopper device closer to the engine to control the output shaft's rotation, allowing for reduced speed differences and increased torque capacity without synchronizing input and output speeds, enabling prompt mode shifts and reducing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque limiter is disposed between the input shaft of the differential gear unit and the first rotary element to reduce torque applied to the stopper device, then the stopper device is protected from damage, but a space for arranging the torque limiter is additionally required resulting in growth in size of the vehicle
Solution Approach 1:
The clutch is designed to perform multiple functions: it serves as both the engagement device for connecting/disconnecting the engine from the differential gear unit and as the torque limiter protecting the stopper device. By making the clutch multi-functional, the patent eliminates the need for a separate torque limiter component, thus protecting the stopper device without increasing vehicle size.
2Volume of moving object
If the clutch for disconnecting the engine from the differential gear unit is disposed between the input shaft of the differential gear unit and the first rotary element to serve as a torque limiter, then vehicle size is reduced, but a synchronization of input speed and output speed has to be carried out to reduce speed difference to almost zero during engagement, resulting in long time to complete shifting operation and deteriorated acceleration response
Solution Approach 1:
The system performs preliminary actions by controlling the first motor to reduce the speed difference between input and output shafts before clutch engagement, and by pre-positioning the clutch to serve as both engagement device and torque limiter. This preliminary speed synchronization and component positioning enables faster mode shifting without requiring extensive speed matching during the actual engagement, thus reducing the overall shifting time and improving acceleration response.
3Loss of time
If the engagement device is brought into engagement without synchronizing input speed and output speed to reduce speed difference to zero, then mode shifting time is reduced and acceleration response is improved, but excessive torque may be applied to the stopper device causing damage
Solution Approach 1:
The patent changes the torque parameter by using the clutch to gradually increase torque transmission capacity during engagement, rather than immediately transmitting full torque. The clutch allows torque to build up progressively as its engagement progresses, which reduces the shock torque that would otherwise be applied to the stopper device during rapid mode shifting, thus protecting the stopper device while maintaining fast shifting performance.
4Power
If the clutch is brought into engagement to shift drive mode from single-motor mode to dual-motor mode, then dual-motor power is achieved, but synchronization of speeds and subsequent torque generation by the first motor after engagement completion increases the time required for mode shifting
Solution Approach 1:
The system maintains continuous useful action by controlling the first motor to generate torque continuously during the clutch engagement process, rather than waiting for engagement completion. The first motor begins generating torque before the clutch is fully engaged and continues throughout the engagement, ensuring that dual-motor power is achieved as soon as possible without requiring a separate torque generation phase after engagement, thus reducing mode shifting time while maintaining dual-motor power capability.
Data Source
AI summary
A control system for a hybrid vehicle configured to promptly shift a drive mode. In the single-motor mode, the vehicle is powered by a second motor while bringing an engagement device into disengagement and stopping the engine. In the dual-motor mode, the vehicle is powered by both a first motor and the second motor while bringing the engagement device into engagement and stopping a rotation of the output shaft of the engine by a stopper device. When shifting the drive mode from the single-motor mode to the dual-motor mode, the control system controls the first motor in a manner such that a speed difference between an input speed and an output speed of the engagement device is reduced while increasing a torque transmitting capacity of the engagement device.