Jigsaw Scotch Yoke With Spherical Bushing to Reduce Wear
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Solution Overview
Problem
Existing jigsaw power tools with scotch yoke mechanisms experience excessive wear due to cylindrical bearing surfaces, leading to reduced longevity and increased friction during reciprocating motion conversion.
Innovation Solution
A jigsaw with a scotch yoke mechanism featuring a spherical bearing surface on the bushing and a laterally extending slot with a chamfered edge, allowing orbital rotation and minimizing mechanical interference, combined with a counterweight for balanced reciprocating motion, enhancing durability and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical bearing surface is used in the scotch yoke mechanism, then the structure is simple and easy to manufacture, but excessive wear occurs and friction increases during reciprocating motion conversion
Solution Approach 1:
The patent applies spheroidality by replacing the traditional cylindrical bearing surface with a spherical bearing surface in the scotch yoke mechanism. This spherical surface allows for orbital rotation of the bushing while converting rotational motion to reciprocating motion, reducing mechanical interference and wear between components. The spherical geometry enables smoother motion conversion and extends component longevity.
2Reliability
If a spherical bearing surface with orbital rotation is implemented, then wear and friction are reduced, but the device complexity increases
Solution Approach 1:
The patent merges the bushing component with the scotch yoke mechanism, integrating the spherical bearing surface directly into the bushing structure that is already part of the scotch yoke assembly. This integration approach reduces the need for separate wear-reduction components while achieving the desired orbital rotation and motion conversion functionality, thereby limiting the increase in overall device complexity.
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 spherical bearing surface and counterweight configuration reduce wear and tear, increasing the longevity of the drive assembly and minimizing friction, resulting in improved performance and extended tool life.
Implementation Method 1
The spherical bearing surface and counterweight configuration reduce wear and tear, increasing the longevity of the drive assembly and minimizing friction
Data Source
AI summary
A jigsaw including a housing, a handle extending transverse from the housing in a direction along a handle axis, a battery selectively coupled to the handle, a foot plate configured to contact a workpiece during a cutting operation, a drive assembly powered by the battery and including a motor, a transmission driven by the motor, an output spindle driven by the transmission and coupled to a saw blade. The jigsaw further includes a scotch yoke mechanism to convert a rotational motion of the transmission to a reciprocating motion of the output spindle and the saw blade generally along a vertical axis that is perpendicular to the handle axis, wherein the scotch yoke mechanism includes a bushing eccentrically mounted to a driven gear of the transmission. The bushing includes a spherical bearing surface received within a laterally extending slot of the output spindle for sliding movement therewith.