Threaded Compression Limiter for Thermal-Cycle Joint Reliability
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Solution Overview
Problem
Current compression limiters in automotive assemblies face challenges such as increased machining costs due to the need for a springing flange and specialized fasteners, and thermal cycling causes deformation and loss of connection between plastic and metal components, leading to stress/strain issues.
Innovation Solution
A self-tapping compression limiter with a body having a threaded portion and a shoulder that provides a positive lock interface, allowing torque application via shaped drives like male or female hex drives, reducing tolerance and maintaining bolt clamp load transfer while minimizing plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a springing flange is incorporated into the sleeve design to permit deflection during fastener assembly, then the compression limiter can accommodate thermal cycling and material deformation, but additional machining is required and clearance must be provided increasing device complexity
Solution Approach 1:
The compression limiter body is segmented into distinct functional zones: a threaded portion for engagement, a shoulder for load bearing, and a reduced tolerance section for precise positioning. This segmentation allows each zone to perform its specific function optimally without requiring complex machining throughout the entire component.
Solution Approach 2:
Different sections of the compression limiter have different tolerance requirements and geometric properties. The shoulder portion has specific dimensional characteristics for load distribution, while the threaded portion has different requirements for engagement. This local differentiation of properties eliminates the need for uniform complex machining while maintaining reliability.
2Reliability
If a protruding shank rib member is added to the fastener to prevent release from the sleeve assembly, then the fastener remains secured during installation, but the fastener requires special machining increasing manufacturing cost
Solution Approach 1:
The retention function is extracted from the fastener itself and transferred to the compression limiter design. The limiter's geometric features and tolerance control provide the retention mechanism, eliminating the need for special fastener modifications and reducing fastener manufacturing complexity.
Solution Approach 2:
The compression limiter acts as an intermediary component between the fastener and the sleeve assembly. It provides the retention function through its own geometric features rather than requiring modifications to either the fastener or the sleeve, simplifying the overall system.
3Reliability
If tolerance is reduced in the compression limiter design to improve connection reliability, then the interface connection between plastic and metal components is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The compression limiter is designed with pre-established geometric features (shoulder, threaded portion) that inherently control tolerances and ensure proper positioning before assembly. This preliminary design approach builds in tolerance control rather than requiring post-assembly adjustments or extremely tight manufacturing tolerances across all features.
Solution Approach 2:
The solution addresses tolerance issues by introducing dimensional variations in specific zones (such as the shoulder radius and reduced tolerance section) rather than uniformly tightening all dimensions. This targeted dimensional control achieves reliability while maintaining manufacturability.
Data Source
AI summary
A self-tapping compression limiter for a structure of an automotive vehicle. The limiter includes a body having a first end extending to a second end. The body has a bore formed through the first and second ends defining a longitudinal axis. The body has an outer wall having a shoulder radially extending from the outer wall and formed adjacent one of the first and second ends to reduce tolerance to the structure. The outer wall has a threaded portion formed about the longitudinal axis. The threaded portion is matingly cooperable with the structure to provide a positive lock interface between the limiter and the structure.