Linear Motor Compressor Free-Piston Control
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Solution Overview
Problem
Existing linear motor compressors for gas compression, particularly in natural gas vehicles, operate at limited and economically disadvantageous conditions due to rigid movement sequences tied to crankshaft rotation, leading to inefficiencies and high energy consumption.
Innovation Solution
A method for operating a linear motor compressor with a free-piston arrangement driven by an electric linear motor, allowing for controlled movement with specified state variables such as speed, acceleration, and force profiles, enabling optimized operation for energy efficiency and flexibility in compressing or expanding gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the linear motor compressor operates with rigid movement sequences tied to crankshaft rotation, then the compressor can maintain stable operation, but the energy consumption increases and efficiency decreases
Solution Approach 1:
The patent applies dynamics by transitioning from rigid, fixed movement sequences to dynamic, adaptive control of the free-piston arrangement. The control device adjusts piston position, speed, and acceleration in real-time based on operating conditions, allowing the system to optimize energy consumption while maintaining operational stability. This dynamic control enables the compressor to adapt its movement profile to match actual load requirements rather than following predetermined crankshaft-driven sequences.
Solution Approach 2:
The patent implements parameter changes by varying key operational parameters including piston speed, acceleration, position, and force profiles. The control device modifies these parameters dynamically during operation to optimize the balance between energy consumption and compression efficiency. By changing parameters such as stroke rate, stroke length, and intermediate position holding, the system achieves lower energy consumption while maintaining the required compression performance.
2Productivity
If the linear motor compressor uses fixed movement sequences, then the device structure can be simplified, but the productivity and efficiency are reduced
Solution Approach 1:
The patent replaces the traditional mechanical crankshaft-driven piston movement system with an electrically controlled linear motor system. This substitution eliminates the need for complex mechanical linkages, connecting rods, and crank mechanisms while enabling precise electronic control of piston motion. The linear motor directly drives the piston along its stroke path, allowing independent control of position, speed, and acceleration through electrical signals rather than mechanical constraints, thereby improving compression efficiency without excessive complexity increase.
Solution Approach 2:
The control system employs dynamic adjustment of piston movement parameters including speed profiles, acceleration rates, and position timing. The control device continuously monitors operating conditions and adjusts the free-piston arrangement's movement characteristics in real-time to optimize compression efficiency. This dynamic control approach replaces fixed, predetermined movement sequences with adaptive control that responds to actual system state, improving productivity through optimized timing and parameter selection.
3Adaptability or versatility
If the linear motor compressor operates continuously at resonant frequency, then the operation is stable, but the operating possibilities are extremely limited
Solution Approach 1:
The patent applies dynamics by enabling the free-piston arrangement to operate at variable frequencies and movement profiles rather than being locked to a single resonant frequency. The control device adjusts piston speed, acceleration, and position dynamically, allowing the system to adapt to different operating conditions such as varying load demands, temperature conditions, and compression ratios. This dynamic control maintains operational stability through active regulation while dramatically expanding operating possibilities beyond continuous resonant frequency operation.
Solution Approach 2:
The patent implements multi-functionality by designing the linear motor compressor to perform multiple operating modes including compression, expansion, heating, and cooling cycles. The free-piston arrangement can be controlled to execute different thermodynamic cycles depending on application requirements. The system can operate in single-acting or double-acting modes, adjust stroke length and frequency, and respond to varying environmental conditions, making it a universal solution for diverse thermal management applications rather than being limited to a single resonant frequency compression mode.
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 approach allows for efficient operation by reducing flow resistance during gas ejection, minimizing energy consumption, and extending the duration of the ejection phase, thereby enhancing the overall efficiency and flexibility of the linear motor compressor.
Implementation Method 1
a free-piston linear motor compressor in which the compressor is designed as a reciprocating compressor, the linear motor is designed with two poles
Implementation Method 2
the entire free-piston linear motor compressor is operated at a resonant frequency
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for operating a linear motor compressor (1) comprising an electric linear motor (14), a cylinder (2), and a linearly movable free piston assembly (16) comprising a piston (3). The cylinder (2) and the piston (3) form a compression chamber (5), and a free piston assembly (16) is directly driven by the linear motor (14) and is moved back and forth between an upper dead center (XOTP) and a lower dead center (XUTP) along a stroke path (X). The compression chamber (5) is supplied with a fluid from the outside, and the supplied fluid is compressed or expanded in the compression chamber (5) and subsequently dispensed back outside. At least one state variable (Ztarget) is specified for the linear motor compressor (1), and the linear motor (14) is actuated such that the linear motor compressor (1) exhibits the specified state variable (Ztarget).