The measuring device of the step volume inside the high-precision bell-type gas flow standard device

Abstract

The invention relates to a high-precision bell-type gas flow standard device inner order volume measurement device, which comprises a support. The support is fixedly provided with a vertical movement mechanism capable of moving vertically; the upper part of the vertical movement mechanism is provided with a rotation mechanism; the rotation mechanism provides a driving force by a rotation servo motor; a rotation measurement arm is driven to rotate; two ends of the rotation measurement arm are respectively provided with a pneumatic contact-type length gauge; the measurement head of each length gauge ejects to contact the inner wall of the bell body, the chord length of the bell body section is thus measured, the rotation measurement arm rotates for an X angle, the measurement head of the contact-type length gauge ejects again to contact the inner wall of the bell body, the other chord length of the bell body section is measured, and 360 / X chord lengths are measured until one-circle rotation; a control system thus calculates a bell body section area; and the vertical movement mechanism vertically moves for a set distance, and according to different bell body section areas and the vertical movement mechanism movement distances, the order volume of the bell-type gas flow standard device in an effective measurement section can be calculated.

Description

technical field [0001] The invention relates to a device for detecting the volume accuracy of a bell-jar type gas flow standard device, in particular to a device for detecting the step-by-step volume of a high-precision bell-type gas flow standard device, and belongs to the technical field of bell-jar volume accuracy detection. Background technique [0002] The bell-jar gas flow standard device is the main equipment for calibrating gas flow meters, and it is also the basic standard device for gas flow in the low pressure range. As the original standard realized according to the basic definition of flow, whether the value can be accurately traced to the basic quantities such as length and time depends on whether the volume of the bell jar can be accurately measured. Since the bell jar discharges part of the volume of gas step by step from top to bottom, the key to verifying the volume of the bell jar is to measure the volume in steps of its effective metering section. [000...

AI Technical Summary

Problems solved by technology

[0005] Due to the high shape and position accuracy of the housing itself, the volume of gas discharged from the bell jar is directly related to the internal volume of the housing. Therefore, the outer diameter measurement methods such as the π ruler method, the laser tracking method and the outer diameter micrometer method are indirect measurements and must be combined with the wall thickness. Therefore, a large measurement uncertainty (about 0.02%) will be introduced; considering the working characteristics of the bell-type gas flow standard device, what needs to be obtained is the standard air volume discharged by the cover through any starting and ending positions, and the axis Due to the limitations of the radial and radial scales, it is difficult for general-purpose length measuring instruments to measure the fractional volume according to the working method of the bell jar, and the section of the bell jar cannot be a circle in the strict sense, so the calculation method of replacing the surface with a circle introduces measurement uncertainty ; Even if the roundness of the section is good, the rotating spindle of the length measuring device cannot be placed exactly in the center of the housing

[0006] In summary, the existing size measurement method is difficult to measure and has high measurement uncertainty. How to provide a high-precision measuring instrument and measurement method for measuring the internal step volume of a bell-type gas flow standard device is a challenge in this field. technical challenge

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