Tape Measure Motor Assembly Spring Retention
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Solution Overview
Problem
Conventional tape measures have limitations in the engagement between the tape and the motor assembly, particularly in the assembly of the spring into the motor, which affects the locking mechanism and belt clip functionality, leading to inefficiencies in the retraction and extension of the tape.
Innovation Solution
The proposed solution involves a motor assembly with a spring fixed between a hub and a combination of inner and outer motor bodies, utilizing a backer plate and adhesive or rivets to secure the spring, and a belt clip system that allows for left- or right-handed configurations, enhancing the engagement between the tape and the motor assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional springs are attached to reels or cases via physical interlocks, cut into the spring, or assembled with physical retainers such as rivets, screws, or bolts, then the spring connection is secure, but the assembly process is complex and time-consuming
Solution Approach 1:
The patent merges the spring attachment function with the motor body structure by integrating a recess directly into the motor body that receives and secures the spring end. This eliminates the need for separate physical retainers such as rivets, screws, or bolts, thereby reducing assembly complexity while maintaining secure spring connection. The motor body itself becomes both the mounting structure and the securing mechanism.
2Ease of manufacture
If adhesive is used to secure the spring, then the assembly process is simplified, but waiting for adhesive curing is required which reduces productivity
Solution Approach 1:
The patent segments the spring attachment function into two distinct mechanisms: a recess in the motor body for positioning and a separate locking mechanism (such as a deformable portion or mechanical latch) for immediate securing. This segmentation eliminates the need for adhesive curing time while maintaining simple assembly, as the mechanical locking portion can be engaged instantly without waiting for chemical bonding.
3Reliability
If the spring is fixed between the hub and the combination of inner motor body and outer motor body, then the spring is securely retained, but the assembly requires multiple components increasing device complexity
Solution Approach 1:
The patent makes the motor body multi-functional by integrating multiple roles into single components. The motor body simultaneously serves as: (1) the mounting structure for the spring, (2) the securing mechanism through its recess and locking features, and (3) part of the drive mechanism itself. This multi-functionality reduces the number of separate components needed while maintaining secure spring retention, as the motor body performs both structural and fastening functions.
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 improves the locking mechanism and belt clip functionality, ensuring reliable retraction and extension of the tape, while also simplifying the assembly process and reducing the need for waiting for adhesive curing, thus enhancing user convenience and operational efficiency.
Implementation Method 1
a spring, wherein a first end of the spring is connected to a hub received in the motor body, and wherein a second end of the spring extends out of an opening in the inner motor body
Implementation Method 2
The coupling region comprise a rivet or an adhesive between the motor body, the spring, and the backer plate to fix or bond the motor body, the second end of the spring and the backer plate together
Data Source
Figure 1
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AI summary
A motor assembly (300) for a tape measure comprises a motor body having an inner motor body (340) and an outer motor body (350) and a spring (370). A first end of the spring (370) is connected to a hub (390) received in the motor body. A second end (360) of the spring (370) extends out of an opening (380) in the inner motor body (340), and is received between the inner motor body (340) and the outer motor body (350) such that the spring (370) is fixed between the hub (390) and the combination of the inner motor body (340) and outer motor body (350).