Positive Displacement Expander Stop Position Control for Reliable Restart
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Solution Overview
Problem
The existing refrigeration cycle apparatuses face challenges in controlling the stop position of the orbiting scroll or rolling piston in the expander, leading to potential startup failures due to insufficient driving force when reactivating the system, especially when the refrigerant is discharged through a communicating path connecting the intermediate expansion chamber to the low-pressure side.
Innovation Solution
A positive displacement expander with a communicating path allowing expansion chambers to communicate with the expander discharge side, equipped with an opening and closing device that equalizes high and low pressures to control the stop position of the orbiting scroll or rolling piston, ensuring it stops at a predetermined position when high-pressure fluid supply is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the refrigerant in the expansion chamber is discharged through a communicating path connecting the intermediate position to the outlet position, then power recovery efficiency is improved, but the orbiting scroll or rolling piston may stop at an intermediate position causing startup failure
Solution Approach 1:
The communicating path is preliminarily configured to connect the intermediate position of the expansion chamber to the outlet position, enabling the orbiting scroll or rolling piston to be preliminarily positioned at a predetermined location before startup. This preliminary positioning ensures that sufficient pressure difference exists to generate adequate driving force when the system restarts, preventing startup failure while maintaining power recovery efficiency during operation.
2Reliability
If the orbiting scroll or rolling piston stops at a predetermined position, then startup reliability is improved, but control complexity increases
Solution Approach 1:
The system utilizes the self-service principle where the refrigerant pressure differential automatically positions the orbiting scroll or rolling piston at the predetermined location through the communicating path. The pressure difference between the expansion chamber and outlet position naturally drives the moving component to stop at the desired position without requiring external control mechanisms, sensors, or actuators, thereby maintaining simplicity while ensuring reliable startup.
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 solution effectively prevents startup failures by ensuring the orbiting scroll or rolling piston can be easily resumed, maintaining sufficient driving force and enhancing the reliability of the refrigeration cycle apparatus.
Implementation Method 1
when supply of the high-pressure fluid is stopped, the opening and closing device is opened by the time when high and low pressures between each expansion chamber and the expander discharge side are equalized
Data Source
AI summary
Disclosed is a positive displacement expander equipped with an expansion mechanism in which power is generated using fluid energy produced while a high-pressure fluid, supplied to a plurality of expansion chambers partitioned by an orbiting scroll or a rolling piston, is being expanded and decompressed. The expander includes a communicating pipe that allows each of the expansion chambers to communicate with an expander discharge side and an opening and closing device disposed on the communicating pipe. When supply of the high-pressure fluid is stopped, the opening and closing device is opened by the time when high and low pressures between each of the expansion chambers and the expander discharge side are equalized, thus stopping the orbiting scroll or the rolling piston at a predetermined position so that an expander obtains sufficient driving force when resuming.