Profiled Locking Washer Structure for Vibration-Resistant Screw Joints

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Solution Overview

Problem

Existing screw connection securing methods, such as lock washers with radial ribs, are inadequate in preventing loosening under strong vibrations and dynamic loads, particularly in motor vehicles.

Innovation Solution

A disc-shaped body with profiled inner and outer annular surfaces is used in conjunction with a screw or nut, creating a form fit that prevents rotation and ensures secure assembly by having the screw or nut emboss into the inner surface and the outer surface impress into a component's contact surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a disc-shaped body with profiled surfaces is used to create positive fit locking, then anti-loosening reliability is improved, but the device complexity increases compared to traditional lock washers

Engineering Contradiction:
Improvelocking reliabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The disc-shaped body merges multiple functions into a single component: it acts as both a locking element and a spacer, provides two positive locking interfaces simultaneously, and ensures correct assembly orientation. This merging reduces the need for multiple separate components while maintaining high locking reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The disc-shaped body is designed with universal applicability through its dual-profile configuration that can engage with different screw heads or nuts while providing consistent locking performance. The symmetric design allows it to function correctly regardless of assembly direction, enhancing versatility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If the inner and outer annular surfaces are made as mirror images, then correct assembly orientation is ensured, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveassembly orientation guidanceVSAvoidsymmetry precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

While the overall design aims for symmetry to ensure correct assembly orientation, the inner and outer annular surfaces employ asymmetric profile configurations relative to each other. This controlled asymmetry provides orientation guidance without requiring perfect mirror-image symmetry between the two surfaces, balancing ease of assembly with manufacturing feasibility.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP3705740B1Screw connection and method for preventing the loosening of the screw connection
Publication Date: 2022.02.23 MAN TRUCK & BUS SE
  • EP3705740B1 patent drawingFigure 1~5
  • EP3705740B1 patent drawingFigure 6~7
  • EP3705740B1 patent drawingFigure 8

AI summary

The device (10) has a disc-shaped body (12) with a front (14), a back (16), and a through-hole (18), preferably central, connecting the front (14) to the back (16). The front (14) and the back (16) each have an inner annular surface (20, 22) that is flat and an outer annular surface (24, 26) that is profiled. Advantageously, the device (10) can be used together with a screw (30) or a nut (38) with a profiled underside (36, 40). When tightened, the profiled underside (36; 40) of the screw head (32) or the nut (38) can be impressed into one of the inner, flat annular surfaces (20, 22) of the disc-shaped body (12), while one of the outer, profiled annular surfaces (24, 26) of the disc-shaped body (12) is impressed into a contact surface (42) of a component (44) to be connected with the screw connection (48).