The low-temperature rotary valve type high-pressure helium gas with liquid nitrogen pre-cooling is firstly exchanged with the low-pressure helium gas in the first-stage heat exchanger, and then enters the liquid nitrogen precooler, and then enters the second-stage heat exchanger after being pre-cooled by liquid nitrogen. Further, after heat exchange with the low pressure helium gas, the pulse tube enters the pulse tube. After a period of time, the valve head is turned to a certain position, so that the high pressure channel is disconnected from the pulse tube, and the charging process ends; the valve head continues to rotate to a certain position so that the heat exchanger The low-pressure channel is connected to the pulse tube, and the gas in the pulse tube is expanded and cooled, and then heat exchanges with the high-pressure helium gas through the secondary heat exchanger and then into the compressor, and the valve head continues to rotate to cut off the low-pressure channel and the pulse. The connection of the tubes and the expansion process are completed, thus forming a complete cycle.
The motor used for the low temperature rotary valve of low temperature rotary valve is driven by 70LY54 permanent magnet DC torque motor produced by Beijing Micromotor General Factory. Its rated current is 1.26A, rated voltage is 48V, maximum no-load speed is 900r/min, and minimum torque is 0.637Nm. The operating frequency of the chiller is controlled by adjusting the input voltage of the DC motor. All other components are designed and processed by us.
Because the rotary valve works in the low temperature zone, in order to reduce the axial leakage heat loss, the transmission shaft of the DC motor and the rotary valve valve head adopts a straightened thin-walled stainless steel pipe for the low-temperature rotary valve valve head and the valve seat structure. The structure of the valve head and the valve seat of the low-temperature rotary valve is shown. The valve head is made of wear-resistant black PTFE material for the working environment, and the valve seat is made of stainless steel. The high and low pressure between the inlet and the exhaust is mainly between them. The difference (in addition to the preload of the spring) is pressed together to prevent crosses between high and low pressure. Such a structure has certain disadvantages such that frictional heat is inevitably generated when the valve head is rotated. Since the rotary valve is arranged in the low temperature part of the refrigerator, the helium gas entering and exiting the pulse tube must pass through the valve head, and the friction heat will be carried away by the refrigerant gas, which consumes the cooling capacity and thus affects the performance of the refrigerator.
A low temperature rotary valve will produce a special case at the cold end of the pulse tube of this refrigerator. In the pulse tube refrigerator using the regenerator, the cold end of the pulse tube always has airflow in and out during the operation of the refrigerator; in this pulse tube refrigerator, when the valve head is in a position such that the pulse tube is neither high nor high When it is not connected to the low voltage, the flow rate of the cold end of the pulse tube is zero at this time, thus causing the discontinuity of the working fluid flow, which is bound to adversely affect the performance of the refrigerator.
Pneumatic Screw Locking Machine
Pneumatic Screw Locking Machine,Screw Fastening Robot,Screw Tightening Machine,Automatic Screw Tightening Machine
Suzhou Huaweile Automation Technology Co., Ltd , https://www.hwlelocking.com