Screw compressor and chiller unit using same
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Solution Overview
Problem
Conventional screw compressors experience over-compression, leading to hit sound and vibration due to the repeated opening and closing of the valve body, which is inefficient in reducing pressure imbalances and requires a spring for operation, causing durability and adjustment issues.
Innovation Solution
A screw compressor design featuring a valve body driven by a piston and electromagnetic valves, controlled by sensors detecting suction and discharge pressures to manage over-compression, eliminating the need for a spring and reducing vibrations and hit sounds by precise pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a spring is used to bias the valve body to reduce over-compression, then over-compression is reduced, but the valve body repeatedly opens and closes causing hit sound and vibration
Solution Approach 1:
The patent replaces the mechanical spring-based valve body driving system with an electromagnetic valve system. The electromagnetic valve opens and closes the bypass flow path based on pressure sensor feedback, eliminating the need for a spring and the associated repeated mechanical contact that causes hit sound and vibration.
Solution Approach 2:
The patent employs pressure sensors to detect the pressure in the compression work chamber and provides feedback to the electromagnetic valve control. This allows the system to dynamically adjust the bypass flow path opening based on actual pressure conditions, preventing over-compression without the oscillatory behavior caused by spring-based systems.
2Ease of operation
If a spring is used to operate the valve body, then the valve body can respond to pressure changes, but durability and adjustment issues arise
Solution Approach 1:
The patent replaces the mechanical spring system with an electromagnetic actuation system controlled by pressure sensors and a control unit. This substitution eliminates the durability and adjustment issues associated with mechanical springs while maintaining the ability to respond to pressure changes through electronic control.
Solution Approach 2:
The system uses pressure sensors to automatically detect pressure conditions and the electromagnetic valve to self-regulate the bypass flow path opening based on detected over-compression, eliminating the need for manual spring adjustment and providing reliable automatic operation.
3Stress or pressure
If the valve body is opened to reduce over-compression, then pressure imbalance is reduced, but the valve body immediately closes due to spring force causing repeated cycling
Solution Approach 1:
The patent uses pressure sensors to continuously monitor the compression work chamber pressure and provides feedback to the electromagnetic valve control. This feedback mechanism allows the system to maintain the bypass flow path opening as long as over-compression conditions persist, preventing the immediate closing behavior caused by spring force and reducing operational cycling.
Solution Approach 2:
By replacing the spring-based mechanical system with an electromagnetic valve system, the patent eliminates the inherent oscillatory behavior where the valve immediately closes after opening. The electromagnetic system can maintain a stable opening state controlled by pressure feedback, improving operational efficiency.
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 effectively reduces over-compression, minimizes valve body vibrations and hit sounds, and ensures reliable operation across varying compressor pressures and rotation speeds, enhancing performance by precise control of the valve body.
Implementation Method 1
introducing a fluid on a discharge side into the cylinder chambers to move the piston; discharging the fluid introduced into the cylinder chambers to a suction side
Implementation Method 2
a plurality of valve means provided at the pressure discharge path or the communication path, the valve means changing pressure in the cylinder chambers
Implementation Method 3
a male rotor and a female rotor rotating while engaging with each other with rotation axes thereof in substantially parallel to each other; a compression work chamber formed by the male rotor and the female rotor
Data Source
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AI summary
Screw compressor (130) including a valve hole (28) formed at a discharge side end surface of the discharge casing (16) and at a position opening to a compression work chamber (36A, 36B); a bypass flow path (29) connecting the valve hole and a discharge chamber with each other; and a valve body (31) arranged in the valve hole; cylinder chambers (35, 70) provided on a rear surface side of the valve body (31); a piston (51) reciprocally moving in the cylinder chambers; a rod (53) connecting the piston (51) and the valve body (31); communication paths (81, 120, 121, 83, 84, 85, 86, 112) for introducing a fluid on a discharge side into the cylinder chambers; a pressure discharge path (80, 80a, 80b, 85, 86, 112) for discharging to a suction side the fluid introduced into the cylinder chambers; a plurality of valve means (42, 43) provided at the pressure discharge path or the communication path and changing pressure in the cylinder chambers; and a controller (113) controlling the plurality of valves means to open the valve body upon detecting over-compression and close the valve body upon not detecting the over-compression.