Rotary Cam Mechanism for Compact Reciprocating Motion Conversion
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Solution Overview
Problem
Existing mechanisms for converting rotating motion to reciprocating motion, such as in small hand-held devices like electric brushes, require significant space and are not compact or lightweight, making them inconvenient for such applications.
Innovation Solution
A device comprising a rotatable shaft with a groove and a second element constrained to move along its axis, featuring a pin that engages with the groove to convert rotating motion into reciprocating motion, utilizing a cam track on a crown gear wheel to define the motion of a push-pull rod, allowing for compact and efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cranks and crankshafts or Scotch Yokes are used to convert rotating motion into reciprocating motion, then the conversion function is achieved, but the device requires considerable space and becomes heavy
Solution Approach 1:
The invention extracts the essential motion conversion function from the complex crank-crankshaft mechanism, retaining only the necessary elements (cam track, pin, follower) to achieve reciprocating motion from rotation, thereby eliminating unnecessary components and reducing space requirements
Solution Approach 2:
The invention uses a cam track with an asymmetric cross-section that is rotated about an axis, creating a three-dimensional motion conversion mechanism that achieves reciprocating motion through rotational movement of the cam track itself, rather than through linear movement of a crankshaft
2Reliability
If traditional motion conversion mechanisms are used, then reliable motion conversion is achieved, but the device becomes complex and occupies significant axial space
Solution Approach 1:
The invention combines the cam track, rotation axis, and motion conversion function into a single integrated component structure, where the cam track itself performs the motion conversion through its asymmetric cross-section geometry, eliminating the need for separate crankshafts and connecting rods
Solution Approach 2:
The cam track serves multiple functions simultaneously: it guides the pin movement, defines the reciprocating motion path through its asymmetric cross-section, and converts rotational motion to reciprocating motion, making the mechanism simpler while maintaining reliability
Data Source
AI summary
A device for converting a rotating motion into a reciprocating motion comprises a rotatable shaft carrying a first grooved element, a second element constrained to move along an axis of said second element, and a pin carried on the second element. The pin may be engaged in the groove on the rotatable shaft so that as the rotatable shaft rotates, the pin moves in the groove thereby causing the second element to move along its axis. The shape of the groove defines the motion of the second element. There is also disclosed an electric brush assembly and an electric tool assembly comprising such a device.