Multi-Piston Cam Geometry for Constant Fluid Volume Delivery
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Solution Overview
Problem
Existing multi piston machines are limited by the common factor between the number of pistons and lobes, restricting the symmetry in piston movement and the relationship between fluid volume and rotation angle, which complicates achieving a constant fluid volume at the working port with each rotational position.
Innovation Solution
The first and second numbers of pistons and lobes are selected arbitrarily without a common factor, and the valve assembly is configured with multiple switching positions to ensure a constant angular interval between reference positions, allowing for a consistent fluid volume delivery at the working port across rotor positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of pistons and lobes are selected with a common factor to achieve symmetric piston movement, then the relationship between fluid volume and rotation angle becomes constant, but the flexibility in selecting numbers is restricted
Solution Approach 1:
The patent introduces asymmetric first sections with non-zero angular extent that break the traditional symmetric piston-cam configuration. This allows achieving constant fluid volume delivery without requiring a common factor between piston count and lobe count, thereby resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The patent applies different angular extents to different first sections (local differentiation) rather than uniform treatment. By assigning specific angular portions to each first section, the system achieves constant fluid volume delivery while allowing arbitrary selection of piston and lobe numbers, eliminating the common factor restriction.
2Device complexity
If all first sections are configured with zero angular extent to maintain symmetry, then the piston movement remains simple, but the constant relationship between fluid volume and rotation angle cannot be achieved with arbitrary numbers
Solution Approach 1:
The patent changes the parameter of angular extent from zero (traditional symmetric case) to non-zero values for the first sections. This parameter change enables the system to achieve constant fluid volume delivery with arbitrary piston and lobe numbers, while the overall mechanism remains relatively simple through controlled angular portions.
Data Source
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AI summary
The invention concerns with a rotor having multiple pistons (1.1 - 1.12) contacting a cam surface (21) having first and second sections (81; 82), which are arranged alternately with respect to a rotation of the rotor. According to the invention set of reference positions (91) of the rotor is defined for each of the named switching positions of the valve assembly respectively, wherein at each reference position (91) a piston (1.1 - 1.12) connected to the first working port enters a second section (82), due to a rotation of the rotor, wherein an angular extent of at least one first section (81) with respect to the axis of rotation (13) is greater than zero, such that in at least one switching position of the valve assembly the pistons (1.1 - 1.11) contributing to the displacement volume of the multi piston machine (10') pass the associated reference positions (91) at essentially constant angular intervals during a complete revolution of the rotor.