Hybrid Transmission Clutch Control for Smooth Gear Shifts
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Solution Overview
Problem
Existing automatic transmission control methods cause lag feeling and torque variation during gear shifts in hybrid vehicles, especially when the electric motor performs power generation during gear shifts, leading to increased speed change time and perceived driver discomfort.
Innovation Solution
An automatic transmission control device that adjusts the releasing and connecting speeds of the clutch in conjunction with the electric motor's output state, providing assist torque during clutch release and engagement to synchronize torque transitions and reduce lag feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the speed of disengaging the friction clutch is increased to reduce variation in torque during speed change, then torque variation is reduced, but the speed change takes more time and the driver perceives a lag feeling
Solution Approach 1:
The control device determines the motor's output state (power generation or torque output) before initiating clutch disengagement. Based on this preliminary determination, it selects the appropriate disengagement speed strategy: high speed when motor torque is available, low speed when motor is generating power. This preliminary action allows the system to optimize clutch disengagement speed in advance, avoiding torque variation while maintaining fast response.
Solution Approach 2:
The clutch disengagement speed is made dynamic rather than fixed. The control device adjusts the disengagement speed based on the motor's real-time output state. When the motor can provide torque, the clutch disengages quickly; when the motor is generating power, the clutch disengages slowly. This dynamic adjustment resolves the contradiction between fast response and smooth torque transition.
2Ease of operation
If the friction clutch is gradually disengaged to minimize perceived deceleration during gear shift, then comfort is improved, but the speed change time increases and lag feeling occurs
Solution Approach 1:
The clutch disengagement process is made dynamic by adjusting the disengagement speed according to motor output state. Instead of always using gradual disengagement, the system switches between gradual (low speed) and rapid (high speed) disengagement based on whether the motor is generating power or providing torque. This dynamic approach maintains comfort when needed while reducing lag when possible.
Solution Approach 2:
The motor acts as an intermediary to compensate for torque loss during clutch disengagement. When the clutch is disengaged quickly, the motor provides assist torque to maintain wheel torque. When the motor is generating power, it cannot provide assist torque, so the clutch must disengage slowly. This intermediary role of the motor allows the system to achieve fast disengagement without comfort loss under certain conditions.
3Device complexity
If the motor transmits no torque during clutch disengagement to simplify control, then control complexity is reduced, but torque variation increases and lag feeling occurs
Solution Approach 1:
The motor serves as an intermediary to compensate for torque variation during clutch disengagement. When the clutch disengages quickly, the motor provides assist torque to maintain stable wheel torque. The control device monitors motor output state and activates this intermediary function only when needed, based on whether the motor can provide torque without conflicting with power generation.
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
This approach reduces torque variation and lag feeling during speed changes, shortens the speed change time, and minimizes energy consumption by optimizing clutch speed changes based on the electric motor's output state, enhancing the driving experience and efficiency.
Implementation Method 1
causing the motor to output speed-change assist torque
Data Source
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AI summary
An automatic transmission control device mounted on a hybrid vehicle 1 including an engine 2, a motor 4, a transmission 3 that changes a speed of rotation of the engine and transmits the rotation to a drive shaft 11, and a clutch 31 that releases or connects power transmission between the engine and the drive shaft, wherein the automatic transmission control device includes a control unit 8 that, in a clutch releasing process during a speed change of the transmission, changes a releasing speed of the clutch and causes the motor 4 to output a speed-change assist torque, at a timing according to an output state of torque of the motor at a start of the speed change of the transmission.