Linear Compressor Piston Position Control Without Separate Sensors
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Solution Overview
Problem
Linear compressors face challenges in accurately detecting the absolute position of a piston without a separate sensor, leading to difficulties in controlling piston movement and resulting in noise and potential collisions, which affect efficiency and lifespan.
Innovation Solution
A control system that uses motor voltage and current sensing to estimate piston stroke, calculate compensation values, and detect absolute piston position, allowing for precise control of piston movement without additional sensors, thereby reducing noise and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor is used to detect piston position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses the motor's own voltage and current signals to detect piston position, eliminating the need for separate sensors. The motor serves dual purposes: driving the piston and providing position information through its electrical characteristics.
Solution Approach 2:
The patent replaces mechanical position sensors with an electrical field-based detection method. By monitoring motor voltage and current, the system infers piston position without mechanical contact or additional sensing components.
2Ease of operation
If piston movement is not mechanically restrained, then ease of operation is improved, but reliability deteriorates due to potential collisions
Solution Approach 1:
The system continuously monitors motor current and voltage to detect piston position in real-time. When the piston approaches top dead center, the feedback signal triggers a voltage adjustment to prevent collision, maintaining both freedom of movement and safety.
Solution Approach 2:
The control system proactively adjusts motor voltage before the piston reaches top dead center, preventing collision before it occurs. This preliminary action maintains piston freedom while ensuring reliability.
3Productivity
If stroke voltage is increased to improve compression, then productivity is improved, but harmful factors increase due to piston collisions
Solution Approach 1:
The system dynamically adjusts stroke voltage based on real-time piston position feedback. Voltage is optimized for compression efficiency during most of the stroke but reduced near top dead center to prevent collisions, achieving both high productivity and safety.
Solution Approach 2:
The patent changes the voltage parameter dynamically throughout the compression cycle. High voltage is applied during the compression phase for productivity, while voltage is reduced near the end of the stroke to prevent harmful collisions.
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 solution enables reduced noise and increased efficiency by preventing piston collisions, extending the lifespan of components and maintaining accurate piston positioning within the cylinder.
Implementation Method 1
a linear motor used... Since the linear motor directly generates a linear driving force by itself
Data Source
AI summary
Provided is a linear compressor capable of reducing noise and manufacturing cost. The linear compressor includes a piston reciprocating within a cylinder, a motor providing a driving force for movement of the piston, a sensing unit sensing a motor voltage and a motor current related to the motor, a discharge part installed at one end of the cylinder and adjusting discharge of a refrigerant compressed within the cylinder, and a controller detecting a load variation of the motor using at least one of the motor voltage and the motor current, calculating a compensation value related to a position of the piston each time a load variation of the motor is detected, and detecting an absolute position of the piston using the calculated compensation value.