Linear Electrical Machine with Segmented Cylindrical Stator
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Solution Overview
Problem
Free piston engine generators face challenges in achieving high electrical efficiency, effective piston motion control, and cost-effective design due to the mismatch between the piston and combustion chamber diameters, leading to complex and expensive mechanical solutions for sealing and alignment.
Innovation Solution
A linear switched reluctance or switched flux generator design with a cylindrical stator secured within a cylinder housing, featuring segmented elements with low Young's Modulus and coated with hard materials, and a piston with a length at least five times its diameter, allowing for axial flux topology with minimal eddy current losses and improved control authority.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electrical machine diameter is increased to achieve sufficient air gap area for given combustion chamber geometry, then the power output is improved, but the mechanical complexity and cost increase due to complex sealing and alignment requirements
Solution Approach 1:
Instead of increasing the electrical machine diameter to achieve sufficient air gap area, the patent inverts the approach by using a smaller diameter electrical machine with a correspondingly smaller diameter piston. The air gap area is maintained at an optimal value rather than being scaled up, thereby reducing mechanical complexity while preserving power output efficiency
Solution Approach 2:
The patent changes the diameter parameter of both the electrical machine and piston to be equivalent or closely matched, rather than having the electrical machine diameter be larger. This parameter change optimizes the air gap area and eliminates the need for complex mechanical solutions for sealing and alignment
2Area of stationary object
If the piston diameter is increased to match the electrical machine diameter, then the air gap area is improved, but the sealing and alignment complexity increases
Solution Approach 1:
The patent inverts the conventional approach by not increasing the piston diameter to match a larger electrical machine. Instead, it reduces both dimensions to equivalent values, maintaining sufficient air gap area while eliminating the need for complex sealing and alignment mechanisms
Solution Approach 2:
The cylinder housing is designed to perform multiple functions: it provides structural support, cooling, and coaxial alignment of the electrical machine and piston. This multi-functionality eliminates the need for separate alignment mechanisms, reducing overall device complexity
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
This design enables a free piston engine with higher electrical efficiency, improved piston motion control, and reduced costs by maintaining equivalent diameters for the air gap and combustion chamber, enhancing the power output matching and reducing mechanical complexity.
Implementation Method 1
as it reciprocates within the cylinder it generates an electric current in a second coil that surrounds the cylinder
Implementation Method 2
the piston carries a first coil and as it reciprocates within the cylinder it generates an electric current in a second coil that surrounds the cylinder
Data Source
Figure 1
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Figure 4
AI summary
A linear electrical machine comprising a movable piston, an axially segmented cylinder having least one magnetically permeable segment and a bore configured to allow the piston to move within the cylinder, a cylinder housing having a bore for receiving the segmented cylinder, and means for securing the segmented cylinder in place within the cylinder housing. This arrangement permits the construction of a free piston engine linear with improved piston position control, more consistent combustion and improved electrical conversion efficiency.