PLC Module Sealing Structure for Shock-Resistant Waterproof Connections

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Solution Overview

Problem

Conventional programmable logic controllers (PLCs) face issues with maintaining waterproofness and dustproofness due to the swaying of module units caused by external shocks, which can damage the sealing members.

Innovation Solution

The PLC design includes a base unit with a substrate and base case, module units with engagement mechanisms and elastic members to secure the connection, and sealing members to maintain waterproofness and dustproofness. The elastic members exert force to press the engagement mechanisms against holding parts, and the sealing members are strategically placed to seal gaps between the base case and module case.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If module units are connected to the base unit using only engagement mechanisms without screws, then ease of operation is improved, but reliability deteriorates due to swaying from external shocks

Engineering Contradiction:

Improveease of installationVSAvoidconnection stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent employs an elastic member (spring) that dynamically adjusts to external forces, maintaining constant contact pressure between the module unit and base unit. This dynamic compensation prevents connection loosening under vibration while preserving easy engagement during installation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The elastic member is pre-loaded to provide beforehand cushioning against external shocks and vibrations. This prior cushioning prevents the engagement mechanism from loosening under anticipated external forces, ensuring reliable connection without requiring additional fastening elements.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If sealing members are provided between base case and module units, then waterproofness and dustproofness are improved, but the sealing members are easily damaged by vibration from module unit swaying

Engineering Contradiction:

Improvewaterproofness and dustproofnessVSAvoidsealing member durability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The elastic member dynamically compensates for relative movements between the module unit and base unit, maintaining constant engagement pressure. This prevents vibration-induced swaying that would otherwise damage the sealing member, while preserving the sealing function.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The engagement mechanism with elastic member provides preliminary anti-action against vibrations before they can transmit to the sealing member. By counteracting vibrational forces at the engagement interface, the sealing member is protected from damage while maintaining its sealing capability.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If the engagement mechanism is pressed firmly against the holding part, then connection stability is improved, but the load on the sealing member increases

Engineering Contradiction:

Improveconnection stabilityVSAvoidsealing member load

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The elastic member provides dynamic, compliant pressing force that adapts to the sealing member's承受能力. This dynamic force application maintains connection stability while avoiding excessive static load that would damage the sealing member.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The elastic member changes the force parameter from a fixed high load to a dynamic, self-regulating force. This parameter change allows sufficient engagement pressure for stability while automatically limiting the load on the sealing member to safe levels.

Inventive Principle:

Principle #35Parameter changes

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

This design effectively reduces the load on the sealing members, preventing damage from external shocks and maintaining the waterproofness and dustproofness of the PLC.

Implementation Method 1

an elastic member to exert a force in a first direction, which is a direction in which the connection unit moves away from the base unit, for pressing the engagement mechanism of the connection unit against the at least one holding part of the base unit

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12225676B2Programmable logic controller, and base unit and module units thereof

Publication Date: 2025.02.11 MITSUBISHI ELECTRIC CORP

AI summary

A programmable logic controller capable of maintaining waterproofness or dustproofness includes a base unit with a substrate, a base case housing the substrate, and at least one holding part to hold a connection unit which is one of a plurality of module units. The connection unit includes a module-side connector, an engagement mechanism to be detachably engaged with the at least one holding part, and a module case with a fitting tenon to be engaged with the base case. The programmable logic controller includes an elastic member to apply a force in a first direction, which is a direction in which the connection unit moves away from the base unit, thereby pressing the engagement mechanism of the connection unit against the at least one holding part of the base unit, and a sealing member to seal a gap between the base case and the fitting tenon of the module case.