Cable Shield Connecting Assembly for Electric Motor Grounding

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Solution Overview

Problem

Existing cable fixation methods for electric rotary motors are cumbersome, costly, and inefficient in securing and grounding braided shielding, often requiring manual adjustment and protruding components that compromise motor size and safety.

Innovation Solution

A cable shield connecting assembly featuring a mounting plate with a cavity and grommet, where a clamp or washer is press-fitted against the grommet to secure and cut braided shielding, eliminating the need for additional clamps and reducing assembly complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cable glands are used to secure and ground cables to the housing, then reliable cable fixation and grounding are achieved, but the assembly becomes more expensive and complex

Engineering Contradiction:
Improvecable fixation reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the cable securing function and the grounding function into a single integrated mounting plate assembly. The mounting plate simultaneously provides mechanical support for the cable gland and establishes electrical ground connection through its contact with the housing, eliminating the need for separate grounding components and reducing assembly complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The mounting plate serves multiple functions: it provides mechanical support for the cable gland, establishes electrical ground connection, and structurally integrates with the housing. This multi-functional design replaces what would traditionally require multiple separate components, reducing both cost and complexity while maintaining reliability.

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

2Ease of manufacture

If grommets made of insulating material are used to secure cables, then cost is reduced, but additional clamps are required for grounding which protrude and increase motor size

Engineering Contradiction:
Improvemanufacturing costVSAvoidmotor height
Core Design Contradiction:
Ease of manufactureVSLength of stationary object

Solution Approach 1:

The mounting plate integrates the grounding function directly into the cable securing assembly. By providing a ground contact surface on the mounting plate itself, the invention eliminates the need for separate protruding clamps, thereby maintaining the cost benefits of using insulating grommets while avoiding the space penalty of additional grounding components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention extracts the grounding function from separate protruding clamps and integrates it into the mounting plate structure. This removes the harmful protruding elements that increase motor height while preserving the essential grounding capability through the mounting plate's contact with the housing.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If manual adjustment and cutting of braided shielding is required, then proper grounding can be achieved, but labor time and assembly complexity increase

Engineering Contradiction:
Improvegrounding effectivenessVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The mounting plate is pre-configured with an integrated ground contact surface and structured to automatically position and secure the braided shielding during assembly. This preliminary preparation of the mounting plate structure enables the braided shielding to be grounded and secured in a single operation without requiring manual adjustment or separate cutting steps, reducing assembly time while maintaining grounding effectiveness.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3787123B1Cable shield connecting assembly for electrical device and method for securing and grounding a cable to a cylindrical housing of an electric rotary motor
Publication Date: 2023.01.18 ETEL SA
  • EP3787123B1 patent drawingFigure 1~5
  • EP3787123B1 patent drawingFigure 6~9

AI summary

The present invention relates to a cable shield connecting assembly (10) for securing and grounding a cable (30) to the housing of an electrical device. The cable (30) comprises a cable jacket (32) and braided shielding (34) extending from an end portion of the cable jacket (32). The cable shield connecting assembly (10) comprises: i) a mounting plate (20) having a cavity (22) and an aperture (24) arranged on a bottom side of the cavity (22), and ii) a grommet (12) having an inner diameter inside which the end portion of the cable jacket (32) is fitted, and upper and lower portions (14a, 14b) extending on both sides of an edge of the aperture (24) of the mounting plate (20), wherein the upper portion (14a) of the grommet (12) is fitted inside the cavity (22). The cable shield connecting assembly (10) further comprises a clamp (16) pressed-fitted against the upper portion (14a) of the grommet (12) inside said cavity (22) to squeeze therebetween said braided shielding (34).