Hybrid Transmission Control With Timed Motor Assist During Shifts
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Solution Overview
Problem
Existing hybrid vehicle transmission control methods, such as JP 2019-55771 A, face drivability issues when the electric motor assists during gear shifts, leading to variations in torque during speed changes.
Innovation Solution
The hybrid vehicle employs an automatic transmission control device that manages torque by adjusting the releasing and connecting speeds of the clutch in multiple steps, using the motor to provide assist torque during clutch release and engagement, ensuring a smoother torque transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric motor transmits no torque at the start of the gear shift phase, then energy consumption of the electric motor is reduced, but drivability is affected when the electric motor performs travel assist
Solution Approach 1:
The patent dynamically adjusts the clutch engagement/disengagement strategy based on whether the electric motor is providing travel assist. When travel assist is active, the clutch is engaged more quickly to maintain torque delivery and drivability. When travel assist is not active, the clutch is disengaged more completely to reduce energy consumption. This dynamic adaptation resolves the contradiction between energy efficiency and drivability.
Solution Approach 2:
The control device changes the torque transmission parameters by adjusting the clutch engagement state based on the travel assist condition. The clutch engagement rate and timing are modified as control parameters to balance energy consumption and drivability requirements under different operating conditions.
2Stability of the object's composition
If the clutch is gradually disengaged and engaged during gear shift, then torque variation is reduced, but speed change time increases
Solution Approach 1:
The electric motor provides preliminary torque assistance before the clutch is fully disengaged during gear shift. This preliminary action ensures that torque delivery to the wheels is maintained during the transition, allowing the clutch to be disengaged and re-engaged more quickly without causing excessive torque variation or drivability issues.
3Loss of time
If the clutch engagement rate is increased during gear shift, then speed change time is reduced, but torque variation increases
Solution Approach 1:
The electric motor acts as an intermediary to compensate for torque variations caused by rapid clutch engagement. When the clutch engagement rate is increased to reduce speed change time, the electric motor provides additional torque to smooth out the transitions, preventing excessive torque variation while allowing faster gear shifts.
Data Source
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AI summary
An automatic transmission control device for a hybrid vehicle 1 comprising an engine 2, a motor 4, a transmission 3 that changes a speed of rotation of the engine 2 and transmits the rotation to a drive shaft 11, a clutch 31 that releases or connects power transmission between the engine 2 and the drive shaft 11, and a control unit 8, wherein the control unit 8 changes a releasing speed of the clutch 31 in a clutch releasing process during a speed change of the transmission 3 and causes the motor 4 to output speed-change assist torque at a timing according to an output state of torque of the motor 4 at a start of the speed change of the transmission 3.