Torque Converter Stud Welding for Hermetic Cover Sealing
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Solution Overview
Problem
Existing torque converter designs face challenges in creating a strong, hermetic seal between the cover and the studs, which can lead to oil leakage and reduced connection strength, especially under varying engine conditions.
Innovation Solution
The torque converter design incorporates a cover with pressed-out portions and studs featuring an annular projection that are welded together using capacitive-discharge welding, forming a hermetic seal around the holes and enhancing the connection strength by moving the weld location to the interior side of the cover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stud attachment methods are used, then assembly is simpler, but the hermetic seal and connection strength are insufficient leading to oil leakage
Solution Approach 1:
The annular projection is pre-formed on the stud during stud manufacturing, before assembly. This preliminary action ensures that when the stud is installed and welded to the cover, the projection is already positioned to create the hermetic seal around the hole, eliminating the need for additional sealing components or complex assembly steps while ensuring reliable sealing.
Solution Approach 2:
The annular projection acts as an intermediary element between the stud and the cover. It provides a dedicated sealing surface that mediates the connection between these two components, creating a hermetic seal while also serving as a reinforcement for the weld joint, thus solving both the sealing and strength issues simultaneously.
2Strength
If welds are placed directly under tensile load, then connection is direct, but fatigue resistance and weld strength are reduced
Solution Approach 1:
The connection function is segmented into two distinct roles: the annular projection handles the hermetic sealing function, while the weld handles the structural attachment function. This segmentation allows the weld to be optimized for strength without bearing the full tensile load, as the projection's sealing interface shares the mechanical burden, thereby improving fatigue resistance.
Solution Approach 2:
Different regions of the stud-connection system are given different properties: the annular projection is designed with sealing surface characteristics (smooth, conforming to the cover's sealing surface), while the weld zone is designed for maximum bond strength. This local differentiation of qualities allows each component to excel at its specific function without compromising the other.
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 design improves the weldability and connection strength between the studs and the cover, reducing the risk of oil leakage and increasing fatigue resistance by distributing tensile forces effectively, while also reducing the axial length of the torque converter.
Implementation Method 1
The stud is connected to the cover by coalescence between the annular projection and the inner surface creating a hermetic seal around the hole
Implementation Method 2
urging the first and second electrodes towards each other to compress the cover against the projection and, during the urging, applying current to one or more of the electrodes to weld the projection to the cover
Data Source
AI summary
A torque converter includes an impeller and a cover rotationally fixed to the impeller. The cover has opposing inner and outer surfaces and a through hole extending from the inner surface to the outer surface. A stud is attached to the cover. The stud has a head and a shank extending from the head. The head defines an annular projection circumscribing the shank and raised from the head. The stud is disposed on the cover with the shank extending through the hole to project from the outer surface and with the head being connected to the cover by coalescence between the annular projection and the inner surface creating a hermetic seal around the hole.