Segmented Ring Cam Layout for Lower Wear in Fluid-Working Machines
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Solution Overview
Problem
Large ring cam fluid-working machines used in renewable energy applications face challenges with high internal forces and pressures, leading to excessive wear and difficulty in repair, as they require disassembly and costly transportation for maintenance, and existing modular designs suffer from discontinuities that increase wear and maintenance costs.
Innovation Solution
A ring cam design with a wave-like working surface featuring leading and trailing faces with strategically located discontinuities to reduce the force exerted on these regions, minimizing wear and allowing in-situ repair by limiting pressure when the cam engaging element bears on these discontinuities, and using electronically controlled valves to manage fluid flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ring cam is designed as a single large component, then the machine can handle high internal forces and pressures, but repair becomes difficult and expensive requiring disassembly and transportation
Solution Approach 1:
The ring cam is divided into multiple segments that can be independently removed and replaced. Each segment is designed to be separable from the others, allowing individual segment replacement without disassembling the entire ring cam structure. This enables in-situ repair of large fluid-working machines while maintaining the overall strength and pressure handling capability of the complete ring cam assembly.
2Ease of repair
If the ring cam is divided into multiple segments, then repair becomes easier, but discontinuities at segment interfaces increase wear
Solution Approach 1:
The segment interfaces are designed with localized discontinuities positioned at specific regions where the cam engaging elements experience lower forces. The discontinuities are strategically placed in low-stress zones, allowing the high-stress regions to maintain continuous contact surfaces. This local differentiation reduces wear at interfaces while preserving load-bearing performance in critical areas.
Solution Approach 2:
The discontinuities are pre-positioned at predetermined locations during design and manufacturing, specifically placed where cam engaging elements naturally experience reduced forces during operation. This preliminary placement ensures that wear-prone interface regions are avoided during high-load phases, reducing excessive wear while maintaining ease of repair.
3Object-affected harmful factors
If discontinuities are added to the working surface, then wear is reduced by limiting force on certain regions, but the manufacturing complexity increases
Solution Approach 1:
The ring cam is segmented into multiple independent components, each containing predetermined discontinuities in their working surfaces. By distributing discontinuities across separate segments rather than a single monolithic structure, the manufacturing complexity is localized to each segment. This allows standardized segment production with built-in discontinuities that reduce wear, while the overall assembly process remains relatively simple.
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 design reduces wear on the ring cam and cam engaging elements, extends the working lifetime, and enables in-situ repair of large fluid-working machines, reducing maintenance costs and the need for costly transportation.
Implementation Method 1
the ring cam having a wave-like cam working surface for operative engagement with the at least one piston by way of a cam engaging element so as to couple reciprocating motion of the at least one piston to rotation of the ring cam
Implementation Method 2
a low pressure manifold typically acts as a net source of a working fluid and a high pressure manifold typically acts as a net sink for a working fluid
Data Source
Figure 1(a)~1(b)
Figure 2(a)~3
AI summary
A fluid-working machine comprising a ring cam (1), at least one piston (11) defining a working chamber, and at least one valve (19, 21) associated with the or each working chamber for connecting the working chamber alternately to low and high pressure manifolds(23, 25) in phased relationship to cycles of working chamber volume. The ring cam has a wave-like cam working surface for operative engagement with the at least one piston. The waves of the wave-like cam surface each having a leading face (70) and a trailing face (72) and discontinuities (4), such as apertures (4) to retain bolts (3), are located in the working surface on whichever of the leading face and the trailing face the at least one piston does least work during normal operation resulting from the flow of fluid into and out of the working chamber in phased relationship to cycles of working chamber volume. As a result, there is reduced wear on cam following elements, such as piston rollers (9).