Constant pressure type gas flowmeter transfiguration chamber

Abstract

The invention relates to a varactor chamber of a constant voltage type gas flow indicator, belonging to the technical field of vacuum measurement. The varactor chamber comprises a pull rod, a bracket, a pin, a motion block, a bellows, a lead rail cylinder, a fixed block and a joint thereof; the main body of the varactor chamber of the constant voltage type gas flow indicator is a hydraulic thin wall forming bellows, the upper end of which is connected with the motion block and the lower end of which is connected with the fixed block; the motion block is connected with the pull rod by the pin,the pull rod pulls the motion block to move, the motion block compresses or stretches the bellows; the pull rod penetrates through a through hole in the center of the bracket; the lead rail cylinder is arranged in the bellows and is welded at one end of the fixed block, the other end of the fixed block is connected with the joint. The hydraulic thin wall forming bellows is made by stainless steelmaterials. The varactor chamber is completely made from stainless steel. The invention has the advantages of simple structure, small volume, light weight and low cost. By adopting the varactor chamber of the invention, the whole constant voltage type gas flow indicator can be roasted to 150 DEG C, thus facilitating degassing of the flow indicator, reducing gas outlet of the wall of the constant voltage type gas flow indicator and effectively extending the lower limit of flow capacity of the constant voltage type gas flow indicator.

Description

technical field [0001] The invention relates to a variable volume chamber of a constant-pressure gas flowmeter, which belongs to the technical field of vacuum measurement. Background technique [0002] In the document "Design of constant pressure gas micro flowmeter, "China Space Science and Technology", No. 3, 1999, pages 65-71", a constant pressure gas flowmeter variable volume chamber is introduced. The variable volume chamber adopts the structure of the piston hydraulically driving the bellows. When the piston moves in the oil chamber, the bellows is compressed by the hydraulic oil, and the change rate of the volume of the piston is considered to be equal to the volume change rate of the bellows of the variable volume chamber. Among them, a rubber ring is used for dynamic sealing between the piston and the oil chamber. [0003] The disadvantage of this structure is that the temperature change will cause the expansion or contraction of the volume of the hydraulic oil, an...

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Problems solved by technology

[0003] The disadvantage of this structure is that the temperature change will cause the expansion or contraction of the volume of the hydraulic oil, and there is a dead space in the oil chamber, and some gas is dissolved in the hydraulic oil, which will affect the effect of the hydraulic oil on the piston volume. accurate delivery

In addition, the variable volume chamber is composed of an oil chamber and a bellows, which cannot be baked, which is not conducive to the degassing of the variable volume chamber, resulting in a poor measurement lower limit; if the oil chamber is used for too long, the oil chamber will incorporate air bubbles, and a special vacuum pump is required Regular pumping; the rubber ring is used for dynamic sealing between the piston and the oil chamber, and if it is used for too long, it is easy to cause air leakage

The variable capacity chamber has complex structure, large volume, heavy weight and high cost

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