Ultra-precision micro-differential pressure measuring device and ultra-precision differential pressure measuring device

Abstract

The ultra-precision micro-differential pressure measuring device comprises a device body 1 having an inner space part therein, a pressure receiving plate 3 which is installed inside the inner space of the device body 1 and divides the said inner space hermetically into a lower space 7 and an upper part space 8, an electronic weighing and pressure converting device 2 which is installed in the lower space 7, and supports and secures the pressure receiving plate 3, and a liquid sealing part R which liquid-seals the outer peripheral part of the afore-mentioned pressure receiving plate 3 and maintains the air-tightness between the lower space 7 and the upper space 8. A micro-differential pressure between a pressure P1 inside the upper space 8 and a pressure P2 inside the lower space 7 is measured by the electronic weighing and pressure converting device 2 through the pressure receiving plate 3.

Description

FIELD OF THE INVENTION [0001] The present invention is concerned with an ultra-precision micro-differential pressure measuring device and an ultra-precision differential measuring device in which a high-performance electronic weighing and pressure converting device is employed. The present invention is also concerned with an ultra-precision micro-differential pressure measuring device which is used as a standard instrument for a differential pressure gauge, and also used as a tool for measuring the pressure drop characteristics of a low-resistance filter, monitoring the filter characteristics, and assessing the flow characteristics of the fluid equipment which deals with gases under a reduced pressure, and further an ultra-precision differential pressure measuring device widely used for the measurement of the differential pressure of approximately 2-5 atmospheric pressure. BACKGROUND OF THE INVENTION [0002] The Askania type micro-manometer and the liquid column manometer in which th...

AI Technical Summary

Benefits of technology

[0026] According to the ultra-precision micro-differential pressure measuring device in accordance with the present invention, the pressure receiving plate 3 is never affected by a meniscus formed by the sealing liquid 6 because there is no involvement of up and down movements of the pressure receiving plate 3.

[0027] Although the heights of the liquid levels of the sealing liquid 6 which forms two ring-shaped liquid surfaces differ depending on the differential pressure ΔP between the pressure spaces 7 and 8, as will be explained later, it is not mandatory that the areas A1 and A2 of the liquid surfaces should be the same.

[0028] Furthermore, in the event that the shape of the liquid surface changes due to a micro-change of the differential pressure ΔP between the pressure spaces 7 and 8, a change of the meniscus formed by the sealing liquid 6 is caused such that a force that acts on the pressure receiving plate 3 in the upward and downward directions is induced.

[0029] However, precision of the measuring of the differential pressure is not affected because the force is counterbalanced between the ring-shaped liquid levels of the inside and the outside (the two liquid faces).

[0030] With the present invention, the electronic weighing and pressure converting device 2 is installed inside the lower space 7 in the device body 1, and the inside of the device body is divided hermetically into the lower space 7 and the upper space 8 by the pressure receiving plate 3 and the liquid sealing part R at the periphery of the pressure receiving plate 3. Further, the force applied by the differential pressure between the spaces 7 and 8 on the afore-mentioned pressure receiving plate 3 is continuously measured with the electronic weighing and pressure converting device 2, and converted into the differential pressure and outputted in the form of the electric signals.

[0031] As a result, the force exerted by the differential pressure is directly transmitted to the electronic weighing and pressure converting device 2 through the pressure receiving plate 3 fixed on the electronic weighing and pressure converting device 2. Because there exists no mechanical friction part in the transmission route of the force exerted by the differential pressure, precision of the measuring of the differential pressure is remarkably improved. By employing the electronic weighing and pressure converting device 2 with the minimum measurement capacity as suitably chosen, a continuous high-precision measurement of the micro-differential pressure having effective figures of three digits or more becomes possible with the ultra-precision micro-differential pressure measuring device in accordance with the present invention. For example, in the case of the electronic weighing and pressure converting device 2 having a minimum measurement capacity of 0.0001 g, a continuous high-precision measurement of the differential pressure of the water column of a few hundred nanometer order becomes possible.

Problems solved by technology

Furthermore, a method in which the differential pressure is electrically detected by a strain gauge, a semiconductor gauge or the like is also used, but not widely.

This means that it is totally impossible to continuously and accurately measure the micro-differential pressure of the water column of a nanometer (nmAq) order lower than 0.01 mm.

However, this device has a problem that the occurrence of measurement errors arising from the friction of moving or sliding parts and a low degree of mechanical machining precision is unavoidable because the device is so constituted that a force generated by the pressure to be measured is transmitted to an electronic weighing and pressure converting device by way of a stem, a ram and the like with the result that a high-precision measurement of the micro-differential pressure can not be achieved.

Measurement errors due to friction of moving parts are also unavoidable, thus resulting in failure of the high-precision measurement.

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