Torque Converter Lock-up Device Curved Support Member
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Solution Overview
Problem
Existing lock-up devices for torque converters face challenges in utilizing heavyweight torsion springs due to stress concentration issues, leading to increased weight and vibration problems, and struggle to achieve effective torsional vibration attenuation with linear or bilinear torsional characteristics.
Innovation Solution
A lock-up device design featuring an input rotary member, an output rotary member, and an elastic member with a support member that includes a support part and an engaging part, where the support part has a curvature reducing stress concentration and allows for flexible assembly, and a trilinear torsional characteristic setup using pairs of coil springs with varying stiffness stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavyweight torsion springs are used to increase torsional stiffness for vibration attenuation, then torsional vibration attenuation is improved, but stress concentration occurs at the notch regions of the support member
Solution Approach 1:
The support member features a curved outer peripheral surface with continuously varying radius of curvature, eliminating sharp notches and corners. This curvature design distributes stress more evenly throughout the structure, preventing stress concentration at specific points while maintaining the structural integrity needed to support heavyweight torsion springs
Solution Approach 2:
The invention changes the geometric parameters of the support member by continuously varying the radius of curvature along the outer peripheral surface. This parameter variation allows the structure to adapt to different stress conditions, providing higher stiffness where needed while avoiding stress concentration zones, thus enabling the use of heavier torsion springs
2Reliability
If the plate thickness of the support member is increased to handle stress concentration, then stress concentration is reduced, but the weight of the lock-up device is increased
Solution Approach 1:
Instead of uniformly increasing plate thickness, the invention changes the geometric parameters by varying the radius of curvature along the outer peripheral surface. This allows the support member to achieve the required strength and stress distribution through optimized geometry rather than increased mass, maintaining lightweight design while improving reliability
Solution Approach 2:
The curved geometry with continuously varying radius distributes stress more effectively throughout the existing plate structure, eliminating the need for additional thickness. The curvature creates a more efficient stress flow path that maximizes the utilization of the existing material
3Device complexity
If linear or bilinear torsional characteristics are used, then the structure is simple, but effective torsional vibration attenuation across a range of torsional angles is not achieved
Solution Approach 1:
The invention implements trilinear torsional characteristics by dividing the torsional response into three distinct stages with different stiffness values. This is achieved through the curved geometry of the support member that provides progressively increasing resistance to torsional deformation, enabling effective vibration attenuation across a wide range of torsional angles while maintaining a relatively simple single-piece structure
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 reduces stress concentration, allows for weight reduction, and effectively inhibits torsional vibration across a range of torsional angles without increasing weight, enabling flexible design and reliable vibration attenuation.
Implementation Method 1
an elastic member (74a, 74b, 174a, 174b, 274a, 274b) that elastically couples the input rotary member (71) and the output rotary member (22) in a rotational direction
Implementation Method 2
Fluctuation in torque to be inputted from an engine is herein absorbed and attenuated by a plurality of torsion springs disposed in the outer peripheral part of the lock-up device
Implementation Method 3
Torque of the front cover is configured to be transmitted to the lock-up device when a friction facing annularly attached to the outer peripheral part of the piston is pressed onto a friction surface of the front cover
Data Source
AI summary
The lock-up device includes an input rotary member, an output rotary member, an elastic member and a support member. The elastic member elastically couples the input rotary member and the output rotary member in a rotational direction. The support member is rotatably disposed relatively to the input rotary member and the output rotary member. The support member has a support part supporting the elastic member and an engaging part engaged with the elastic member in the rotational direction. The support part of the support member herein has an outer peripheral side support portion supporting the outer peripheral side of the elastic member. Further, the outer peripheral end of the outer peripheral side support portion has a curvature continuously reduced in proportion to distance from the engaging part in the rotational direction.