Torque Converter with Planetary Gear Splitter
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Solution Overview
Problem
Conventional torque converters in automatic transmissions face challenges in achieving low K-factors across the entire speed ratio range, which affects energy transfer efficiency and drivability, particularly at higher speed ratios and during engine idle conditions.
Innovation Solution
A hydrodynamic torque converter assembly with an internal planetary gear assembly that splits torque between the torque converter and a direct path to the transmission input, incorporating a damper and a torque converter clutch, either a friction clutch pack or a face clutch, to reduce the K-factor and enhance coupling point efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional torque converter is used, then the vehicle can stop without stalling the engine and torque can be multiplied in the lower speed range, but the K-factor remains high across the entire speed ratio range reducing energy transfer efficiency
Solution Approach 1:
The torque converter assembly is segmented into multiple independent components: a planetary gear assembly with sun gear, planet gears, and ring gear; a torque converter with pump, turbine, and stator; a damper assembly; and a torque converter clutch. This segmentation allows each component to be optimized for its specific function while working together to reduce the K-factor and improve energy transfer efficiency across the entire speed ratio range.
Solution Approach 2:
The invention merges the planetary gear assembly directly with the torque converter components, creating an integrated assembly where the sun gear connects to the damper and torque converter output shaft, the ring gear connects to the torque converter clutch and pump, and the turbine connects to the clutch. This merging allows torque to be split between the torque converter path and the direct planetary gear path, reducing the K-factor while maintaining a compact structure.
2Ease of operation
If torque converter clutch slip control is improved, then fuel economy and drivability are enhanced, but the K-factor and coupling point efficiency are reduced
Solution Approach 1:
The torque converter clutch acts as an intermediary component between the planetary gear assembly and the torque converter turbine. It provides controlled slip to manage torque transfer, improving drivability and fuel economy. The clutch can be either a friction clutch pack with multiple interleaved discs or a face clutch, both designed to optimize slip control while minimizing energy losses at the coupling point.
Solution Approach 2:
The invention changes the operating parameters of the torque converter assembly by using the planetary gear mechanism to alter torque distribution and speed relationships. The damper assembly, with its springs and damping elements, modifies the mechanical parameters to reduce engine speed flare and improve clutch slip control characteristics across different operating conditions.
3Loss of energy
If the planetary gear assembly is used to split torque, then coupling point efficiency is increased, but the device complexity increases
Solution Approach 1:
The planetary gear assembly is nested within the torque converter housing, with the sun gear, planet gears, and ring gear arranged concentrically. The damper assembly is nested within the sun gear, and the torque converter clutch is positioned between the ring gear and the torque converter pump. This nesting arrangement increases coupling point efficiency by reducing the K-factor while keeping the overall assembly compact, though it does increase structural complexity.
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 solution achieves a reduced K-factor across the entire speed ratio range, improving torque converter clutch slip control and energy transfer efficiency, resulting in better drivability and fuel economy by reducing engine speed flare during pedal tip-in events and increasing efficiency at higher speed ratios.
Implementation Method 1
The sun gear of the planetary gear assembly is coupled to the torque converter output shaft through a spring damper
Implementation Method 2
The sun gear of the planetary gear assembly is coupled to the torque converter output shaft through a spring damper
Implementation Method 3
The torque converter clutch may be either a friction clutch pack (with multiple interleaved discs or plates) or a face clutch
Implementation Method 4
a hydrodynamic torque converter assembly having an internal planetary gear assembly that splits torque between a torque converter and a direct path to the transmission input
Data Source
AI summary
A hydrodynamic torque converter assembly includes an internal planetary gear assembly that splits torque between a torque converter and a direct path to the transmission input as well as a damper and a torque converter clutch. The torque converter assembly includes an input shaft that is driven by the engine output shaft and is coupled to both the planetary gear carrier of the planetary gear assembly and the transmission hydraulic pump. The sun gear of the planetary gear assembly is coupled to the torque converter output shaft through a spring damper. The ring gear of the planetary gear assembly is coupled to one side of the torque converter clutch and the pump of the torque converter. The other side of the torque converter clutch is coupled to both the turbine of the torque converter and the spring damper. The stator of the torque converter is grounded. An alternate embodiment replaces the torque converter with a fluid coupling.