Cam Mechanism for Rotary to Reciprocating Motion Conversion
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Solution Overview
Problem
Existing devices for transforming rotary motion into alternating rectilinear motion, such as slider-crank mechanisms, face issues with high specific pressures requiring efficient lubrication, bulkiness, and potential leakage, which can lead to environmental pollution in sensitive areas like agricultural farms.
Innovation Solution
A compact device with a monoblock shaft and eccentric body, utilizing rolling bearings and a lubrication system with grease, eliminating the need for liquid lubricants and enhancing structural strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slider-crank mechanism is used to transform rotary motion into alternating rectilinear motion, then the motion transformation function is achieved, but high specific pressures occur at the piston pin requiring very efficient lubrication with pressurised or splash lubricants
Solution Approach 1:
The patent replaces the traditional slider-crank mechanism with a cam mechanism where a cam rotates on the crankshaft and directly actuates a follower valve. This substitution eliminates the piston pin connection, thereby eliminating the high specific pressure problem and the associated lubrication requirements. The cam-follower direct actuation system achieves the same motion transformation without the intermediate connecting rod and piston pin assembly.
2Productivity
If a connecting rod is used in the slider-crank mechanism, then the motion transmission is achieved, but the connecting rod becomes bulky and represents the weak point of the system
Solution Approach 1:
The patent extracts and eliminates the connecting rod from the mechanism by using a cam-follower direct actuation system. The cam profile directly imparts the reciprocating motion to the follower valve without requiring a connecting rod. This extraction simplifies the mechanism, reduces bulkiness, and removes the connecting rod as a potential weak point while maintaining the motion transmission function.
3Stress or pressure
If pressurised or splash lubricants are used in the slider-crank mechanism, then the high specific pressures are managed, but lubricant leakage and pouring into the surrounding environment occurs causing environmental pollution
Solution Approach 1:
The patent eliminates the need for pressurised or splash lubrication systems by replacing the slider-crank mechanism with a cam-follower mechanism. Since the cam rotates on the crankshaft and directly actuates the follower without a piston pin connection, there are no high specific pressure contact points requiring intensive lubrication. This substitution eliminates the source of lubricant leakage and the associated environmental pollution risk.
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 solution prevents lubricant leakage and environmental pollution, while providing a robust and reliable mechanism for transforming rotary motion into alternating rectilinear motion, maintaining system integrity even in case of damage.
Implementation Method 1
at least one rolling bearing, 11, operatively arranged between said eccentric body, 7, and said mobile member, 8
Data Source
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AI summary
The present invention concerns a device (1) for transforming rotary motion into alternating rectilinear motion, in particular for pumps, preferably of the agricultural type. The device comprises a shaft (2) that can be made to rotate about its own longitudinal axis ("X") and at least one eccentric body (7) engaged on the shaft (2) to rotate as a unit with it about the longitudinal axis ("X"). The device (1) also comprises at least one mobile member or piston (8) operatively associated with the eccentric body (7) through a connection pin (13) to translate along an axis of movement ("Y") transversal to the longitudinal axis ("X") of the shaft (2). Between the eccentric body (7) and the mobile member or piston (8) rolling connection means (10) are arranged to eliminate liquid lubricants and allow the use of lubricating grease.