Torque Converter Piston Seal Assembly Mitigating Thermal Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torque converters face issues with seal growth due to temperature and misalignment, leading to high fluid flow and delayed clutch response, which affect the performance and reliability of the lock-up clutch.
Innovation Solution
A piston assembly with a dynamic seal comprising a split Teflon ring and an o-ring, where the o-ring is positioned in a groove on the outer circumference of the Teflon ring to counteract seal growth and misalignment, and is connected to the lock-up clutch piston to ensure proper sealing and alignment with the transmission input shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional seal assembly is used in the torque converter, then the structure is simple, but the seal growth due to temperature and misalignment leads to high fluid flow and delayed clutch response
Solution Approach 1:
The seal assembly is divided into two separate rings: an inner ring that contacts the transmission input shaft and an outer ring that contacts the piston. This segmentation allows each ring to independently compensate for misalignment and thermal expansion, preventing seal growth that would otherwise cause high fluid flow and delayed clutch response.
Solution Approach 2:
The seal assembly uses composite material construction with an inner ring and an outer ring made of different materials optimized for their specific functions. The inner ring is designed to accommodate shaft rotation and misalignment, while the outer ring provides sealing against the piston, creating a composite structure that resolves the contradiction between simplicity and reliability.
2Reliability
If a single-ring seal assembly is used, then the manufacturing is simpler, but temperature-induced expansion causes misalignment and high fluid flow
Solution Approach 1:
The seal assembly is segmented into an inner ring and an outer ring that can be manufactured separately and then assembled. This allows each ring to be optimized for its specific thermal and mechanical conditions, with the inner ring handling shaft-related thermal expansion and the outer ring handling piston-related sealing, thereby improving reliability without significantly complicating manufacturing.
Solution Approach 2:
The dual-ring design allows for independent parameter optimization of each ring, such as material composition, thickness, and dimensional tolerances, to account for temperature-induced expansion. The inner ring can be designed with parameters suitable for rotating shaft conditions while the outer ring has parameters optimized for static piston sealing, resolving the contradiction between manufacturing simplicity and sealing reliability under thermal conditions.
3Ease of operation
If the seal assembly allows misalignment, then installation is easier, but fluid flow increases and clutch response delays
Solution Approach 1:
The segmented dual-ring structure allows the inner ring to accommodate misalignment during installation and operation without transmitting it to the sealing interface. The inner ring acts as a floating element that absorbs angular and radial misalignment, while the outer ring maintains proper sealing geometry, thus enabling easy installation while preventing the fluid flow issues that would otherwise result from misalignment.
Solution Approach 2:
The inner ring serves as an intermediary element between the transmission input shaft and the outer sealing ring. It absorbs and isolates misalignment effects, preventing them from reaching the critical sealing interface between the outer ring and the piston, thereby maintaining fast clutch response while allowing for easier installation and assembly tolerance.
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 effectively limits temperature-induced expansion and misalignment issues, improving the sealing performance and reducing fluid flow, thereby enhancing the responsiveness and reliability of the lock-up clutch in torque converters.
Implementation Method 1
the o-ring may counteract problems of seal growth due to temperature and/or misalignment
Implementation Method 2
A piston assembly with a dynamic seal comprising a split Teflon ring and an o-ring, where the o-ring is positioned in a groove on the outer circumference of the Teflon ring to counteract seal growth and misalignment, and is connected to the lock-up clutch piston to ensure proper sealing
Data Source
AI summary
A piston assembly for a torque converter is provided. The piston assembly includes a seal assembly including an inner ring configured for fixing to an outer circumferential surface of a transmission input shaft. The seal assembly also includes an outer ring on an outer circumferential surface of the inner ring. The piston assembly also includes a lock-up clutch piston including a radially inner end engaging the seal assembly. A method of forming a piston assembly for a torque converter is also provided. The method includes providing an outer ring on an outer circumferential surface of an inner ring to form a seal assembly configured for fixing to an outer circumferential surface of a transmission input shaft and connecting the seal assembly to a radially inner end of a lock-up clutch piston.