Integrated Bearing Retainer for Axial Thrust in Power Tools

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Solution Overview

Problem

Existing impact wrenches face challenges in securely supporting the output shaft for rotation while effectively converting torque into a striking rotational force, particularly under axial thrust loads.

Innovation Solution

The power tool design includes a bearing retainer with a specific configuration to axially and radially secure the bearing to the end cap, ensuring stability and securement of the output shaft during rotation and torque conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a bearing is used to support the output shaft for rotation, then the output shaft can rotate smoothly, but the bearing may become loose under axial thrust loads

Engineering Contradiction:

Improveoutput shaft rotationVSAvoidbearing position stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent introduces a bearing retainer as an intermediary component between the bearing and the motor housing. This retainer features a bearing receiving portion that accommodates the bearing and a flange with radially extending bearing securing portions that engage the bearing outer race. The retainer acts as a mediator to transfer and distribute the axial thrust loads from the bearing to the motor housing, preventing bearing loosening while maintaining smooth rotation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bearing retainer extends axially beyond the bearing in a direction away from the drive assembly, creating an additional dimensional space for load distribution. The flange structure projects radially outward to engage the bearing outer race, adding a radial dimension to the load path. This dimensional extension allows the retainer to effectively counteract axial thrust forces that would otherwise cause bearing loosening.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If the bearing is secured tightly to prevent loosening, then bearing position stability improves, but the bearing may not accommodate axial thrust loads effectively

Engineering Contradiction:

Improvebearing position stabilityVSAvoidaxial thrust load capacity

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The bearing retainer is segmented into distinct functional portions: a bearing receiving portion that accommodates the bearing, a flange with bearing securing portions that engage the bearing outer race, and a motor housing engaging portion that interfaces with the motor housing. This segmentation allows each portion to perform its specific function optimally - the securing portions maintain bearing position stability while the motor housing engaging portion distributes axial thrust loads over a larger area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bearing retainer is pre-installed in the motor housing before the bearing is assembled. This preliminary positioning ensures that when the bearing is installed, it is immediately supported and aligned by the retainer's bearing receiving portion and securing portions. The retainer is already in place to accommodate axial thrust loads, preventing bearing loosening before operational forces are applied.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If a complex bearing securing mechanism is used to prevent loosening under axial loads, then bearing position stability improves, but device complexity increases

Engineering Contradiction:

Improvebearing position stabilityVSAvoidbearing securing structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The bearing retainer merges multiple functions into a single integrated component: it provides bearing support, axial load distribution, and positional stability simultaneously. By combining the bearing receiving portion, flange with securing portions, and motor housing engaging portion into one piece, the design avoids the need for separate retaining rings, clips, or adjustment mechanisms that would increase device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bearing retainer serves multiple functions: it supports the bearing, secures the bearing against axial and radial forces, distributes axial thrust loads to the motor housing, and maintains bearing position stability. This multi-functionality eliminates the need for multiple specialized components, simplifying the overall device structure while effectively addressing bearing securing requirements under axial loads.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12263562B2Bearing retainer for a power tool

Publication Date: 2025.04.01 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A power tool includes a motor housing and a motor supported within the motor housing. The motor includes an output shaft defining an axis. The power tool also includes a bearing configured to support the output shaft for rotation about the axis, an end cap removably coupled to the motor housing, and a bearing retainer integrally formed with the end cap. The bearing retainer is configured to axially and radially secure the bearing to the end cap.