Torque Converter Lock-Up Weld Joint for Low-Distortion Piston Support
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Solution Overview
Problem
Existing lock-up devices for torque converters face challenges with high heat distortion and bead generation during welding of the oil chamber plate to the sleeve, which affects precision and strength, especially in areas supporting the piston.
Innovation Solution
The implementation of butt welding for fixing the oil chamber plate to the sleeve, utilizing annular butt parts and engaging parts to reduce heat penetration and suppress bead formation, while maintaining structural integrity under oil pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lap welding is used to fix the oil chamber plate to the sleeve, then the joint strength is secured, but the member distortion increases and manufacturing precision deteriorates
Solution Approach 1:
The patent changes the welding method from lap welding to butt welding, which fundamentally alters the heat input characteristics and welding geometry. Butt welding requires lower heat input and produces less distortion compared to lap welding, thereby resolving the contradiction between joint strength and manufacturing precision
Solution Approach 2:
Instead of using lap welding where the oil chamber plate is welded onto the sleeve surface, the patent inverts the approach by using butt welding where the oil chamber plate and sleeve are joined end-to-end. This inversion of the welding configuration reduces heat input and distortion while maintaining joint strength
2Strength
If lap welding is used to fix the oil chamber plate to the sleeve, then the joint strength is secured, but the heat input increases causing member distortion
Solution Approach 1:
The patent changes the welding method from lap welding to butt welding, which fundamentally alters the heat input characteristics. Butt welding requires lower heat input compared to lap welding, thereby resolving the contradiction between joint strength and welding heat input
3Strength
If lap welding is used to fix the oil chamber plate to the sleeve, then the joint strength is secured, but welding beads are generated affecting surface quality
Solution Approach 1:
The patent changes the welding method from lap welding to butt welding. Butt welding produces minimal or no welding beads compared to lap welding, thereby resolving the contradiction between joint strength and welding bead generation while maintaining surface quality
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 method allows for lower heat welding with reduced distortion and bead generation, enhancing the accuracy and strength of the welded joint, particularly in critical piston support areas.
Implementation Method 1
a piston (25), and a sleeve (35). The piston (25) is movable in an axial direction, and the piston (25) brings clutch part (24) into a torque transmission state
Implementation Method 2
The second butt part (36b) is butt-welded in contact with the first butt part (35b). When an oil chamber plate is fixed to a sleeve by welding, lap welding is often used. In the case of this lap welding, the amount of heat required to secure the penetration is large. Therefore, the member is distorted.
Data Source
AI summary
A lock-up device includes a clutch part, a piston, a sleeve, and an oil chamber plate. The clutch part is disposed between a front cover and a turbine. The piston is axially movable, and brings the clutch part into a torque-transmission state. The sleeve is fixed to the inner peripheral part of the front cover. The sleeve has a piston support part and a first butt part. The piston support part supports an inner peripheral surface of the piston to be axially movable. The first butt part is formed on the outer peripheral surface of the piston support part. The oil chamber plate is provided between the piston and the turbine. The oil chamber plate has a second butt part. The second butt part is butt-welded with the first butt part. The oil chamber plate forms an oil chamber. Hydraulic fluid is supplied between the oil chamber and the piston.