Terminal Screw with Concentric Blind Hole for Compact Circuit Breaker Installation
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Solution Overview
Problem
Existing connecting arrangements for low-voltage circuit breakers face challenges in installation when there is limited space, as they require a large connection opening or disassembly of the device, and terminals with small cable openings cannot accommodate terminal screws due to insufficient space between the terminal and housing.
Innovation Solution
A connecting arrangement featuring a terminal screw with a through-hole and a concentric blind hole that allows for tool access, enabling secure attachment from the front side without needing to insert tools through the connection opening, and a countersunk head screw for secure fixation without obstructing cable introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a terminal with a small cable opening is used, then the terminal size is reduced and it is suitable for small cables, but there is insufficient space between the terminal and housing wall to install the terminal screw
Solution Approach 1:
The patent implements nesting by placing the blind hole for tool access inside the terminal screw structure. The blind hole is positioned concentrically within the terminal screw, allowing the tool access opening to be nested within the screw body itself. This nested configuration enables tool access without requiring additional external space that would increase terminal size.
Solution Approach 2:
The patent transitions from a two-dimensional planar access approach to a three-dimensional solution by creating a blind hole that extends into the terminal screw body. This dimensional change allows tool access through the terminal screw thickness rather than requiring lateral space, enabling installation in compact configurations where the terminal is positioned close to the housing wall.
2Ease of operation
If the connection opening is made large to accommodate terminal screw installation, then the terminal screw can be installed, but very small electrical connections can deviate sharply because of the large connection opening
Solution Approach 1:
The patent extracts the tool access function from the connection opening by creating a separate blind hole within the terminal screw. This separation allows the connection opening to be minimized for cable stability while the blind hole provides dedicated tool access for terminal screw installation, eliminating the need to enlarge the connection opening.
3Strength
If the terminal is secured to the electrical contact first, then the terminal is firmly attached, but there is no space above between the terminal and switching device housing to enable the terminal screw to be installed
Solution Approach 1:
The patent enables preliminary installation of the terminal screw into the terminal before the terminal is mounted to the electrical contact. The blind hole allows the terminal screw to be partially threaded and secured in advance, and this pre-installed screw remains accessible through the blind hole for final tightening after the terminal is attached to the contact, eliminating the need for vertical clearance.
4Ease of operation
If a different connecting arrangement is used when installation space is too small, then installation is possible, but the terminal must be clamped behind the electrical contact which allows cables to deviate sharply
Solution Approach 1:
The patent inverts the conventional approach by enabling front-side access for terminal screw installation through the blind hole, rather than requiring rear-side clamping. This inversion allows the terminal to be securely attached from the front, providing stable cable positioning while maintaining installation feasibility in compact spaces.
Data Source
AI summary
A connecting arrangement is disclosed for an electrical switching device for attaching an electrical connection to the electrical switching device, including a terminal, a fixing screw and a terminal screw including an external thread. The terminal includes a connection opening for introducing the electrical connection, a fixing opening through which the fixing screw can be passed for the purpose of securing the terminal to an electrical contact of the electrical switching device, and a terminal bore having an internal thread through which the terminal screw can be screwed in for the purpose of retaining the electrical connection. The terminal screw includes a through-hole and, arranged concentrically with respect to the through-hole, a blind hole which is embodied for receiving a turning tool. The blind hole covers the through-hole and has a greater cross-sectional area than the through-hole. An electrical switching device including at least one such connecting arrangement is disclosed.