Piston Rod Rotation via Asymmetric Channels
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Solution Overview
Problem
Fluid dispensing systems, such as those used for spraying paint, experience significant wear due to high pressures and the abrasive nature of the fluids, leading to accelerated wear of components and potential imbalanced reciprocation.
Innovation Solution
A piston rod design with an interior piston chamber, exterior channels, and side bores that connect the chamber to the channels, allowing for axial extension and rotation, which facilitates even wear distribution and minimizes the formation of bypass channels by rotating the piston during reciprocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a traditional reciprocating piston is used in high-pressure fluid pumping, then the pump can generate high fluid pressure, but the piston and interfacing parts experience accelerated wear due to cyclic relative movement and abrasive fluid
Solution Approach 1:
The piston is designed to rotate dynamically about its reciprocation axis during operation. This rotation is achieved through asymmetric channel configurations that create uneven fluid pressure distribution, generating a torque that causes the piston to rotate. The rotation transforms the static reciprocating motion into a dynamic combined motion, distributing wear across different surfaces of the piston and interfacing parts, thereby reducing accelerated wear while maintaining high-pressure pumping capability
Solution Approach 2:
The patent employs asymmetric channel configurations within the piston body, where channels have different orientations, positions, or cross-sectional areas. This asymmetry creates non-uniform fluid pressure distribution during reciprocation, generating a net torque that rotates the piston. The asymmetric design is crucial for inducing rotation and achieving even wear distribution across the piston surfaces
2Device complexity
If the piston reciprocates in a fixed orientation, then the pump structure is simple, but wear becomes concentrated on specific interfacing surfaces leading to imbalanced reciprocation
Solution Approach 1:
The piston transitions from fixed-orientation reciprocation to dynamic rotation during reciprocation. The piston rotates about its reciprocation axis, continuously changing which surfaces contact the cylinder wall and sealing elements. This dynamic orientation change distributes wear more evenly across all piston surfaces, preventing concentrated wear and maintaining balanced reciprocation without requiring complex multi-component mechanisms
Solution Approach 2:
The piston's rotation is self-generated through the asymmetric channel configuration and fluid pressure distribution during normal reciprocating operation. The fluid pressure differential created by the asymmetric channels automatically produces a torque that rotates the piston, eliminating the need for external rotation mechanisms or complex control systems. The system uses its own operating fluid and pressure to achieve the wear-distributing rotation
Data Source
AI summary
A piston rod (27) for a spray fluid pump includes an interior pumping chamber (40), one or more channels (50) formed on the exterior of the piston rod, and one or more side bores (32) extending through the piston rod and in fluid communication with the interior piston chamber and one or more channels. The one or more channels (50) extend at least partially axially and are open along a length of the channel. The one or more channels are angled offset with respect to the reciprocation axis for imparting a rotational moment on the piston rod to cause rotation of the piston rod during reciprocation of the piston rod. A spray fluid pump comprising such piston rod is also disclosed.