Hybrid Transmission Segmented Input Paths
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Solution Overview
Problem
Hybrid transmissions with a single motor and no torque converter face issues such as clutch engagement impacts, performance degradation during low-speed hill climbing, and restricted fuel efficiency due to identical input shafts for engine and motor power, limiting optimal motor efficiency operation.
Innovation Solution
A hybrid transmission design featuring a first and second planetary gear set with multiple rotation elements, clutches, and a motor/generator, allowing for selective connections to optimize power input paths from both the engine and motor, eliminating torque converter slips and enhancing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single motor and no torque converter are used in hybrid transmission, then cost is reduced, but clutch engagement impacts and performance degradation occur
Solution Approach 1:
The transmission system is segmented into distinct power input paths: one for the engine and another for the motor. This segmentation allows independent optimization of each power source's connection to the planetary gear sets, enabling smooth clutch engagement and preventing performance degradation while maintaining cost-effectiveness through single-motor architecture
Solution Approach 2:
The transmission employs dynamic clutch control mechanisms that adjust engagement timing and pressure based on operating conditions. The clutches connecting the engine and motor to respective planetary gear sets are controlled dynamically to prevent impact during engagement and maintain stable operation across varying vehicle speeds and load conditions
2Device complexity
If identical input shafts are used for engine and motor power, then device complexity is reduced, but fuel efficiency is restricted due to limited motor operating point optimization
Solution Approach 1:
The input shaft system is segmented into separate engine input shaft and motor input shaft, each connected to different planetary gear sets. This structural segmentation enables independent rotation speed control for engine and motor, allowing the motor to operate at its optimal efficiency point regardless of engine speed, thereby maximizing fuel efficiency without excessive complexity
Solution Approach 2:
The transmission system enables independent parameter control of engine and motor rotation speeds through separate planetary gear pathways. The motor's rotation speed can be optimized for maximum efficiency independently from the engine's operating parameters, achieving significant fuel economy improvements through parameter optimization
3Ease of operation
If clutch slip is used for power transmission, then ease of operation is improved, but thermal deterioration of clutch and performance degradation occur
Solution Approach 1:
The system replaces traditional torque converter-based mechanical power transmission with a planetary gear set and clutch mechanism. This substitution eliminates the need for continuous clutch slip, reducing thermal deterioration while maintaining smooth power transmission through controlled engagement and mechanical gear ratios
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
The design provides smooth vehicle starts, regenerative braking, and torque assistance for improved drivability, maximizing fuel efficiency by utilizing the motor's optimal efficiency operating point without engine speed limitations.
Implementation Method 1
a first planetary gear set constituted of a complex planetary gear train connected to an input element, a motor/generator, and a first clutch
Data Source
AI summary
A hybrid transmission includes a first planetary gear set and a second planetary gear set. The first planetary gear set is constituted of a complex planetary gear train connected to an input element, a motor/generator, and a first clutch, and has four or more rotation elements. The first rotation element of the first planetary gear set is selectively connected to the input element and the first clutch is installed to selectively stop rotation of a third rotation element of the first planetary gear set. The fourth rotation element of the first planetary set is selectively connected to the motor/generator. The second planetary gear set is connected to an output element, and has four or more rotation elements.