Power Tool Housing Assembly With Offset Screw Layout

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Solution Overview

Problem

Power tools face challenges in smooth assembly and reduced likelihood of upsizing due to complex enclosure structures, leading to increased size and assembly difficulties.

Innovation Solution

The power tool design incorporates a motor with a stator and rotor, a gear system, and a specific screw placement strategy, where first screws fasten the rear cover and motor compartment, and second screws fasten the motor compartment and gear case, positioned differently in orthogonal planes to facilitate smooth assembly and reduce the tool's overall size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If multiple screws are used to fasten enclosure parts, then structural integrity is improved, but assembly complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoidassembly complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The enclosure is divided into multiple parts (motor compartment, gear case, rear cover) that can be assembled separately and then fastened together using screws, allowing for modular assembly while maintaining structural integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Screws are positioned at different locations in a plane orthogonal to the rotation axis, distributing fastening points across multiple dimensions to enhance structural stability while maintaining manageable assembly complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If enclosure parts are designed for structural integrity, then reliability is improved, but the power tool size increases

Engineering Contradiction:

Improvestructural integrityVSAvoidpower tool size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

Screws are strategically positioned at specific locations rather than uniformly distributed, providing structural integrity only where needed while minimizing overall enclosure volume and preventing upsizing of the power tool

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If screws are positioned at different locations, then assembly smoothness is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveassembly smoothnessVSAvoidscrew position precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Screw holes and screw positions are pre-defined and pre-positioned during the design and manufacturing stage, allowing for smooth assembly operations while maintaining precise screw placements through advance preparation rather than requiring high precision during assembly itself

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11738441B2Power tool

Publication Date: 2023.08.29 MAKITA CORP

AI summary

A power tool includes a motor including a stator and a rotor rotatable relative to the stator about a rotation axis, a gear drivable in response to rotation of the rotor, a motor compartment accommodating the motor, a rear cover covering a rear opening in the motor compartment, a gear case accommodating the gear and covering a front opening in the motor compartment, a first screw fastening the rear cover and the motor compartment together, and a second screw fastening the motor compartment and the gear case together, and at a different position from the first screw in a plane orthogonal to the rotation axis.