Low-Profile Switch With Bowed Spring Actuator
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Solution Overview
Problem
There is a need for a thinner yet rugged position sensing switch assembly suitable for industrial applications, particularly in injection molding machines, where the existing micro-switches are not compatible with the lower stop heights used in European and Asian molds, and a better attachment system for the switch assembly to the ejector housing is required, as current methods involve disassembling the mold.
Innovation Solution
A low-profile position sensing switch utilizing a bowed spring actuator with a mounting clip featuring spring biased arms for secure attachment, along with terminal contacts and a bridge contact mechanism that changes state upon compression and release, allowing for secure electrical connections and easy mounting without disassembling the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard micro-switch is used for position sensing, then the switch has sufficient mechanical life and electrical rating, but the switch thickness (0.156 inches) exceeds the available gap (0.118 inches) in European and Asian molds
Solution Approach 1:
The patent reorients the switch from a vertical mounting configuration to a horizontal mounting configuration on the ejector plate. By rotating the switch 90 degrees and mounting it on its side, the thickness dimension becomes the width rather than the height, allowing the switch to fit within the limited vertical gap while maintaining all original mechanical and electrical specifications
Solution Approach 2:
The patent employs a spring-loaded plunger mechanism that provides dynamic adjustment capability. The spring allows the plunger to flex and make contact with the stop under compression, accommodating variations in stop height and positioning tolerance while maintaining reliable electrical contact. This dynamic mechanism enables the switch to function reliably despite the reduced available space
2Reliability
If the switch assembly is mounted using traditional screw attachment methods, then secure attachment is achieved, but the mold must be disassembled to provide access for tapping holes
Solution Approach 1:
The patent divides the attachment system into separate functional elements: a mounting plate with pre-formed attachment features and the main switch body. The mounting plate includes integrated tabs or lugs that can be attached to the ejector plate using external fasteners, eliminating the need to tap holes in the mold itself. This segmentation allows the attachment mechanism to be designed independently of the mold structure
Solution Approach 2:
The mounting plate is pre-prepared with attachment features (such as tabs, lugs, or pre-drilled holes) before installation on the mold. This preliminary preparation allows the final attachment to be completed using simple external fasteners or clips without requiring access to the interior of the mold cavity or disassembly of mold components
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
The solution provides a compact, reliable, and easily mountable position sensing switch that can operate in the thinner European and Asian mold configurations, ensuring accurate position sensing and reducing assembly time by allowing direct attachment to the mold ejector housing without disassembly.
Implementation Method 1
a bowed spring actuating mechanism formed from a bowed piece of spring steel for engaging the plunger of a plunger type switch
Data Source
AI summary
A low profile limit switch utilizes a bowed spring actuator for advancing a bridge contact into and out of contact with a pair of terminal contacts to close and open the switch. The bridge contact is mounted on a glide on an end of the spring and formed from an insulating material. The terminal contacts are spring loaded and maintained in spaced apart and staggered relationship so that only one of the terminal contacts remains in contact with the bridge contact when it is retracted by the bowed spring. A mounting clip including a mounting flange and spaced apart spring loaded arms extending generally perpendicular to the mounting flange is used to mount the switch to a surface proximate an edge without having to obtain any significant amount of vertical clearance above the switch for bolting it to the surface.