Linear Compressor Electro-Magnetic Spring Linear Force Control
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Solution Overview
Problem
Linear compressors in refrigerator appliances face inefficiencies due to high friction from moving parts and require complex active control for piston motion, as well as non-linear spring forces that decrease performance.
Innovation Solution
A linear compressor design incorporating an electro-magnetic spring with ferromagnetic teeth and spring magnets that apply a non-linear force to the piston, ensuring a substantially linear total spring force during compression strokes, enhancing efficiency and performance by controlling the force and frequency of the driving coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional spring is used to urge the piston towards the default position, then the piston can oscillate at resonant frequency, but the spring is inefficient at storing energy and applies non-linear force that decreases compressor performance
Solution Approach 1:
The patent replaces the traditional mechanical spring with an electro-magnetic spring consisting of ferromagnetic teeth and spring magnets. This substitution eliminates the energy storage inefficiencies and non-linear force characteristics of mechanical springs while maintaining the resonant oscillation capability. The electro-magnetic spring applies a substantially linear force to the piston during compression strokes, improving compressor performance.
Solution Approach 2:
The patent changes the fundamental parameter of spring force characteristics from non-linear (traditional spring) to substantially linear (electro-magnetic spring). By controlling the magnetic field strength and tooth geometry, the system achieves linear force-displacement relationship during compression strokes, directly addressing the performance degradation caused by non-linear spring forces.
2Productivity
If a piston and crankshaft mechanism is used to compress refrigerant, then compression can be achieved, but the large number of moving parts generate large friction forces resulting in poor efficiency
Solution Approach 1:
The patent extracts and eliminates the crankshaft mechanism from the compressor system, retaining only the essential piston for refrigerant compression. By removing the connecting rod, crankshaft, and associated moving parts, the system dramatically reduces friction losses while maintaining the core compression function. The piston is directly actuated by electromagnetic forces, simplifying the mechanical structure.
Solution Approach 2:
The patent replaces the mechanical crankshaft-driven piston motion with an electromagnetic driving coil that directly actuates the piston. This substitution eliminates the need for complex mechanical linkages and reduces moving parts, thereby minimizing friction losses and improving overall system efficiency.
3Ease of operation
If active control is applied to stop piston motion at each end of displacement, then precise control can be achieved, but the control system becomes complex and expensive
Solution Approach 1:
The patent utilizes resonant vibration of the piston to achieve automatic stopping at displacement extremes. By operating at the resonant frequency of the piston-spring system, the piston naturally comes to rest at the ends of its stroke without requiring active control intervention. This passive control approach significantly simplifies the control system while maintaining precise piston positioning.
Solution Approach 2:
The system employs self-service control where the resonant oscillation characteristics of the piston-spring system automatically regulate piston motion. The electro-magnetic spring and driving coil work together to create a self-regulating system that stops the piston at appropriate positions without external control signals, reducing system 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
The electro-magnetic spring design improves the linear compressor's efficiency by providing a balanced and linear force application, reducing friction and complexity, thus enhancing the overall performance and energy storage during piston motion.
Implementation Method 1
Linear compressors can include a piston and a driving coil. The driving coil generates a force that slides the piston backward and forwards within a chamber to compress refrigerant.
Implementation Method 2
An electro-magnetic spring includes at least one ferromagnetic tooth. Each ferromagnetic tooth of the at least one ferromagnetic tooth has an outward surface. The outward surface of each tooth of the at least one ferromagnetic tooth is positioned proximate a respective outer surface of the at least one spring magnet.
Data Source
AI summary
A linear compressor is provided. The linear compressor includes an electro-magnetic spring and a casing that defines a chamber. A piston is received within the chamber of the casing. The electro-magnetic spring can apply a non-linear force to the piston such that a total spring force applied to the piston during a compression stroke is substantially linear.