Stirling Machine Generation
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Solution Overview
Problem
Existing Stirling machines face issues with high gas flow rates through conduits leading to increased dead volume, unbalanced pressure forces on cylinders, and accelerated wear on piston rings due to non-parallel alignment, which are exacerbated by thermal expansion and gas flow direction.
Innovation Solution
A Stirling machine configuration with concentrically arranged pistons and heat exchanger modules connected via manifolds and conduits, minimizing dead volume and balancing pressure forces, allowing piston rings to operate within a temperature gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a considerable flow cross section is allowed below the displacer to avoid high pumping losses and pressure pulses, then pumping losses are reduced, but the dead volume of the circuit increases
Solution Approach 1:
The patent introduces a fourth dimension (axial direction) by positioning the flow cross-section above the displacer piston rather than below it. This dimensional repositioning allows the gas flow to occur in a different spatial location, avoiding the dead volume penalty while still providing sufficient flow area to minimize pumping losses and pressure pulses.
2Device complexity
If the conduit between displacer cylinder and power cylinder is made longer to connect volumes below pistons, then the configuration is simplified, but the dead volume increases
Solution Approach 1:
The patent changes the spatial arrangement by connecting the power cylinder volume above the piston rather than below, thereby shortening the conduit length and reducing dead volume without significantly increasing configuration complexity.
3Volume of moving object
If gas conduits are arranged directly between cylinders with flow direction through the cylinder bank plane, then the structure is compact, but unbalanced pressure forces cause cylinder misalignment and piston wear
Solution Approach 1:
The patent extracts the flow cross-section from the plane of the cylinder bank and positions it above the displacer piston in a separate axial location. This separation removes the source of unbalanced pressure forces that cause cylinder misalignment, thereby eliminating the root cause of piston ring wear while maintaining structural compactness.
Solution Approach 2:
The patent introduces an intermediary flow path above the displacer piston that mediates the gas flow between cylinders. This intermediary location balances the pressure forces acting on the cylinders, preventing misalignment and the resulting piston ring wear.
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
Reduces dead volume and eliminates unbalanced pressure forces, enabling efficient operation with reduced wear on piston rings and improved temperature management.
Implementation Method 1
at least three heat exchangers: an expansion heat exchanger, a regenerative heat exchanger and a compression heat exchanger
Implementation Method 2
a regenerative heat exchanger
Data Source
AI summary
The invention is a stirling machine configuration that can be realized with the smallest possible gas dead volumes relative to the pumping losses between the active components (i.e. cylinders, heat exchangers, pistons and displacers. A further object of the invention is to make possible a stirling machine configuration where it is possible to design the machine so that the piston rings can operate at a temperature high enough to avoid brittleness, and low enough to avoid accelerated wear. Even if the temperatures in one or more of the cylinder volumes are outside the temperature region of 0 to 150° C., it will be possible to design the pistons so that the piston rings experience temperatures within this range, as there will be a temperature gradient in both the cylinders and the pistons.