Spring-Loaded Fastening Screw for Tolerance Compensation
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Solution Overview
Problem
Existing fastening systems for electronic units on outer housings face mechanical stress and potential failure due to uncompensated dimensional tolerances, leading to inconsistent attachment over temperature ranges and risk of material deformation.
Innovation Solution
A fastening screw design with a front shank section and a spring element that prestresses against the screw carrier, creating a gap between the thread carrier and screw carrier, allowing for tolerance compensation and maintaining constant contact pressure through a spring force, preventing overloading and ensuring secure attachment over a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fastening screw is tightened to block by pressing the screw carrier onto the thread carrier, then the assembly is securely fastened, but mechanical stresses build up leading to excessive stress and potential failure of the screw carrier
Solution Approach 1:
A cushion element is introduced between the screw carrier and the support element to absorb and distribute mechanical stresses before they reach the screw carrier. This cushioning element prevents stress concentration that would otherwise lead to cracking or fracture of the screw carrier, while still maintaining secure fastening of the assembly.
2Device complexity
If dimensional tolerances are not compensated, then the assembly structure is simple, but mechanical stresses build up due to lack of tolerance compensation
Solution Approach 1:
The cushion element is pre-installed in the fastening structure to automatically compensate for dimensional tolerances. When the screw is tightened, the cushion element deforms to absorb tolerance variations, preventing stress buildup without requiring complex adjustment mechanisms or precision manufacturing.
3Stability of the object's composition
If the screw carrier is pressed onto the thread carrier without a gap, then the attachment is rigid, but permanent static load causes setting behavior and prestress loss over time
Solution Approach 1:
The cushion element maintains a controlled gap between the screw carrier and support element even when fully tightened. This gap prevents continuous static loading that would cause setting behavior in plastic materials, while the cushion element itself provides sufficient support to maintain attachment rigidity and stability.
Solution Approach 2:
The cushion element introduces a dynamic, elastic component to the otherwise rigid fastening system. This allows the connection to adapt to thermal expansion and contraction over time, maintaining prestress levels and preventing the permanent deformation that occurs with rigid, stress-loaded connections.
4Ease of manufacture
If tolerances are not compensated, then the manufacturing process is simple, but the assembly force varies over the intended temperature range
Solution Approach 1:
The cushion element compensates for thermal expansion and contraction of the assembly components across the intended temperature range. As materials expand or contract with temperature changes, the cushion element deforms elastically to maintain consistent contact pressure and secure attachment, without requiring complex thermal compensation mechanisms.
Solution Approach 2:
The cushion element's elastic properties allow it to change its compression state in response to temperature-induced dimensional changes in the assembly. This passive parameter adjustment maintains optimal fastening force across varying temperatures while keeping the manufacturing process simple and the design straightforward.
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 provides a 'floating bearing' effect, compensating for all tolerances and ensuring a defined and constant contact pressure, preventing mechanical stress and material deformation, while allowing for consistent torque tightening and secure attachment.
Implementation Method 1
the spring element is prestressed against the screw carrier and a stop on the screw head side, so that the assembly is pressed against the support element
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a mounting device for fastening an assembly (10) to a component (20), comprising: - a fastening screw (30) with a screw head (31), - a screw carrier (11) connected to the assembly (10), wherein - the shank (32) of the fastening screw (30) has a front shank section (34) with thread (33), which in the fastening position is received by an internal thread (22) on the component (20), and wherein - the shank (32) of the fastening screw (30) has a further shank section (35) for receiving a spring element (40), wherein this spring element (40) is pre-tensioned against the screw carrier (11) and a screw-head-side stop (36) when the fastening screw (30) is screwed into the internal thread (22).so that the assembly (10) is pressed against the support element (23) and, in the fastening position of the front shaft section (34) which is fully screwed into the threaded carrier (21), a gap (50) remains between the threaded carrier (20) and the screw carrier (11). The invention further relates to a fastening screw for this mounting device.