Cold Head Bypass Channel for Overflow Valve Load Relief
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Solution Overview
Problem
Existing low-temperature refrigeration machines with helium as the working gas experience excessive load on the overflow valve due to pulsed gas supply, leading to potential damage, noise, and performance losses, especially when connected to cold heads with high resistance.
Innovation Solution
A cold head design incorporating a bypass channel with a flow control device between the high-pressure and low-pressure connections, allowing excess refrigerant to divert directly from the high-pressure to the low-pressure connection, thereby reducing the load on the overflow valve and potentially omitting the need for it altogether.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cold head with high resistance is connected to the compressor, then cooling performance is improved, but the working pressure on the high-pressure side becomes excessive causing overflow valve damage
Solution Approach 1:
The invention segments the pressure relief function by introducing a separate bypass channel that operates independently from the compressor's overflow valve. The bypass channel divides the high-pressure gas flow into two paths: one through the cold head and another directly back to the low-pressure side, thereby segmenting the load and preventing excessive pressure buildup that would damage the overflow valve.
Solution Approach 2:
The bypass channel acts as an intermediary pathway between the high-pressure and low-pressure sides. Instead of relying solely on the overflow valve for pressure relief, the bypass channel provides an intermediate route that continuously manages pressure differentials, reducing the stress and frequency of operation on the overflow valve.
2Stress or pressure
If the overflow valve frequently opens and closes due to gas oscillations, then pressure regulation is maintained, but the valve seat becomes damaged and noise increases
Solution Approach 1:
The bypass channel provides preliminary pressure relief by continuously managing excess pressure before it reaches critical levels that would trigger frequent overflow valve operation. By establishing this alternative pathway in advance, the system prevents the conditions that lead to repeated valve cycling and subsequent seat damage.
Solution Approach 2:
The bypass channel enables continuous pressure management rather than intermittent relief through the overflow valve. This continuous action smooths out gas oscillations and maintains stable pressure differentials, eliminating the repeated opening and closing cycles that cause valve seat deterioration and noise.
3Ease of manufacture
If the overflow valve is designed for standard differential pressure, then manufacturing is simplified, but it cannot handle high resistance cold heads
Solution Approach 1:
The bypass channel creates a universal pressure management system that works with various cold head resistance levels. By providing an additional pressure relief pathway, the system maintains compatibility with standard overflow valve designs while extending adaptability to high resistance cold heads that would otherwise overload these valves.
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 design reduces the operational stress on the compressor, enhances reliability, increases output, and minimizes the risk of oil leakage, while providing cost savings and consistent noise behavior.
Implementation Method 1
a bypass channel which is arranged between the high-pressure connection and the low-pressure connection or connects the two connections
Implementation Method 2
In a particularly preferred development of the invention, a flow control device is arranged in the bypass channel
Implementation Method 3
a thermodynamic cycle process (Stirling process or Gifford-McMahon process) is carried out with the process gas
Implementation Method 4
While the displacer is periodically moved back and forth by the piston-cylinder unit, heat is constantly withdrawn from the cold head housing
Data Source
Figure 1~2
Figure 3
AI summary
A cold head for cryogenic machines comprises a displacer (72, 76) mounted in a working chamber (38, 40, 46) of a housing (34, 36). The cold head also has a high-pressure connection (64) for supplying highly compressed refrigerant and a low-pressure connection (60) for discharging expanded refrigerant. Also provided is a control valve arrangement (58) for controlling the supply and discharge of refrigerant. According to the invention there is a bypass channel (80) connecting the high-pressure connection to the low-pressure connection.