Screw Terminal Block Rotation Restricting Mechanism

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Solution Overview

Problem

Conventional screw terminal blocks face issues with terminal screws loosening due to impact shocks, as the washer between the terminal screw and the terminal plate can rotate and cause the screw to loosen.

Innovation Solution

A screw terminal block design featuring a rotation restricting part, including protrusions on the fastening plate and locking pieces on the terminal plate, which restricts the rotation of the fastening plate, preventing the terminal screw from loosening, even under torque or impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a washer is interposed between the terminal screw and the terminal plate to enable rotation, then the terminal screw can be tightened, but the washer may rotate due to impact shocks and cause the terminal screw to loosen

Engineering Contradiction:

Improvetightening operationVSAvoidscrew fastening reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The fastening structure is divided into two independent parts: the terminal screw for tightening operation and the fastening plate for positional stability. The rotation restricting part (protrusion and locking pieces) segments the rotational freedom, allowing tightening while preventing unwanted rotation during impact shocks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rotation restricting part acts as an intermediary mechanism between the terminal screw and the fastening plate. It mediates the rotational motion by allowing controlled rotation during tightening while restricting rotation during impact, thus preventing screw loosening.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the washer is allowed to rotate freely, then tightening is easier, but the terminal screw loosens under impact shocks

Engineering Contradiction:

Improvescrew tighteningVSAvoidimpact shock effect

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The rotation restricting part is designed to preemptively counteract the harmful rotational motion caused by impact shocks. The protrusion and locking pieces are positioned to engage before impact occurs, preventing the washer from rotating in the loosening direction even when subjected to sudden forces.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The fastening structure transitions from a static rotation-restricted design to a dynamic one where rotation is permitted during tightening but restricted during normal operation and impact. The rotation restricting part dynamically adapts to different operational states, allowing movement when needed and preventing it when harmful.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8882547B2Screw terminal block and attachment plug including the same

Publication Date: 2014.11.11 PANASONIC HOLDINGS CORP

AI summary

A screw terminal block 10A includes a terminal plate 12 provided with an insertion hole 12a through which a terminal screw 11 is inserted; and a fastening plate 13 provided with a screw hole 13a to which the terminal screw 11 inserted through the insertion hole 12a is screwed. The screw hole 13a is formed in the fastening plate 13, and a protrusion 13b is provided at right and left sides of the fastening plate 13. Upper and lower locking pieces 12b protruding toward the fastening plate 13 are provided at right and left side ends of the terminal plate 12 to sandwich the protrusion 13b therebetween. The locking piece 12b of the terminal plate 12 and the protrusion 13b of the fastening plate 13 are engaged with each other to restrict the relative rotation of the fastening plate 13 and the terminal plate 12.