JPS5857501A - Absolute pressure transducer - Google Patents

Abstract

PURPOSE:To sharply reduce the danger of the operature in high vacuum and to enable the measurement of a high-precision absolute pressure, by further covering a space, where a pressure-sensitive element is vacuum-sealed, with a space part which is brought to a high vacuum state. CONSTITUTION:A pressure of fluid, to be measured, introduced to an introducing part 16 through an inlet 13b, is transferred to a pressure-sensitive element 21 through a diaphragm 15 and a pressure transfer medium 25. The pressure-sensitive element 21 senses a differential pressure between the pressure of the fluid to be measured and a vacuum pressure at the inside of a glass tube 17, serving as a third space, and transfers an electric signal proportioning the differential pressure. Then, even if a very slight leak occurs to, for example, the glass tube 17, serving as the third space, a space around the glass tube 17 forms a fourth space 28 which is vacuum-sealed, and this eliminates the possibility for the glass tube 17 to be reduced in the degree of vacuum at the inside thereof, and prevents the occurrence of an error in a signal outputted from the pressure-sensitive element 21.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention introduces a fluid to be measured and detects the pressure difference between the pressure of the fluid to be measured and a vacuum space provided separately,
This invention relates to an absolute pressure transducer that converts into an electrical signal and outputs it to the outside.

FIG. 1 shows the structure of a conventionally used absolute pressure transducer. A flange 1 having an inlet 11 for introducing the fluid to be measured and the absolute pressure transducer main body 2 are closely fixed through a seal diaphragm 3. ing. The seal diaphragm 3 and the seventh run 1 form a measurement fluid introduction section 4.

Next, the absolute pressure transducer main body 2 has a hole 2a, and a pressure sensitive element 5 is provided so as to close the seal diaphragm S@ of the hole 2m. A space 6 is formed by the pressure sensitive element 5 and the seal diaphragm 3, and a pressure transmission medium 7 is filled in the space 6 to transmit the pressure of the fluid to be measured to the pressure sensitive element 5. ing. In addition, the opposite side of the absolute pressure transducer main body 2 from the pressure-sensitive element 5 is sealed with a lid 8.
and the pressure sensitive element 5 form a space 9. This space 9 is in a vacuum state (-1 if the outside air is 1 kg 7 cm)
Yu/Tan) is formed. The pressure sensitive element 5 senses the pressure difference between the pressure of the fluid to be measured transmitted by the pressure transmission medium 1 and the above-mentioned space 9, converts it into an electric signal proportional to the pressure difference, and transmits the signal via the lead wire 10. It is configured to pass through the through-hole 11 and output to the outside.

Therefore, the fluid to be measured is introduced through the inlet 1a, and the pressure of the fluid to be measured is transmitted to the pressure sensitive element 5 via the seal diaphragm 3 and the pressure transmitting H body 1. Then, the pressure sensitive element SFiS detects the difference between the vacuum pressure in the space 9 and the pressure of the transmitted fluid to be measured, and reads the absolute pressure of the fluid to be measured using an electric signal proportional to the difference. It is output to the outside via IM16.

However, according to the absolute pressure transducer having the above configuration, if even a slight leak occurs at the joint between the absolute pressure transducer main body 2 and the lid 8, the degree of vacuum in the space 9 decreases, and the pressure sensitive element 5 A difference in output KWJ may occur. Furthermore, when the pressure of the fluid to be measured is very low, the space 6 filled with the pressure transmission medium 1 will also be in a near-vacuum state.
Covers the lead wire. There was a problem in that gas was generated due to the insulating support material (Teflon, etc.), resulting in a one-point difference in the output from the pressure-sensitive element 5.

The present invention has been made in view of the above points, and its purpose is to further cover the space in which the pressure sensitive element is sealed in vacuum with a space in a high vacuum state.
Furthermore, since a lead wire for transmitting the output from the pressure-sensitive element can be wired to the same vacuum section, the possibility of a decrease in the degree of vacuum is extremely low, and an absolute pressure transducer that can measure absolute pressure with high precision is provided. It is.

An embodiment of the present invention will be described below with reference to FIG. The absolute pressure transducer main body 12, which has a cylindrical opening, has both sides tightly fixed by the cylinder 11 and the lid 14 through the seal parts 1' and 14a. The lanzo 11 has an enclosed constant fluid inlet 11b, and is connected to the first space by a seal diaphragm 15 interposed between the absolute pressure converter body 12 and the constant fluid inlet 16. is formed. And, for the wound body of the pressure transducer main body 12 which has the shape of a part, #
; Glass tube as this third space where there is glass tube J1 which is the space of 3! ! Inside, there is a tota 18a! y,
Glass tube adsorption r, E18 and evaporation source (
Generally, alkaline earth metal (alkaline earth metal) 1# is provided. This is because in the glass tube 11 which has been closed with high nitrogen fall hardening, the vacuum generates gas from the inner surface of the glass tube 1r, reducing the internal disturbance OX nitrogen.
The evaporation source 19 is heated and evaporated by the heater 18a of the glass tube 11 and the glass tube 11.
This is to prevent the generation of gas by covering the inner surface and to reduce the degree of vacuum. 'Furthermore, the glass tube 1r is made of metal and is integrated with a pressure sensitive element 21 via a hollow shaft 2o. And this integrated glass tube 11. The shaft 2# and the pressure sensitive element 2 are fixed to the absolute pressure converter main body 11 via a support 22, and the contact portion 21 between the absolute pressure converter main body 12 and the absolute pressure converter main body 12 is fixed to the absolute pressure converter main body 11. The welding is worn. And this support 22
A space 24 on side 2 is formed by the seal diaphragm 15 and is filled with a pressure transmission medium 21 . Also, a cover 26 of the lid body 14 is closely fixed to the absolute pressure transducer main body 12 so as to cover the glass tube 11, and the contact portion 2! is in contact all around. This cover 11 is provided with a vacuum exhaust hole 2#a.

In general, the contact portion 2r is welded all around in the atmosphere, and the vacuum exhaust hole 2σa is evacuated to create a fourth space (to be described later) in a vacuum state, thereby sealing the true 9# pore 2s1. However, in this example, the entire circumference welding of the contact portion and the piercing of the vacuum exhaust hole JGM were performed in the same process in vacuum by electron beam welding. This is done in consideration of work efficiency and reliability. The force d-16 and the support 22 form a fourth space 18 outside the glass tube 11, which is the third space. The inside of this fourth space 28 is also in a high vacuum state like the glass tube IF as the third space, and the signal from the pressure sensitive element 21 is relayed therein via the lead wire 2#. A substrate 3o is supported by the shaft 2o. Further, a lead wire J1 that transmits a signal from this board go to the outside is connected to the outside through a large part 12 provided in the absolute pressure transducer main body 11, and is connected to the outside through this hole part 32.
has a hermetic seal structure that allows for complete sealing.

Next, the operation will be explained based on the above configuration.

First, a constant fluid to be copperized is introduced into the introduction part 1c through the introduction port 11b. The pressure of the introduced fluid to be measured is transmitted to the pressure sensitive element 2 via the seal diaphragm 15 and the pressure transmission medium 1j.

The pressure sensing element 21 senses the pressure difference between the pressure of the fluid to be measured and the vacuum pressure inside the glass tube 11, which is the third space, and sends an electric signal proportional to the pressure difference via the lead @ZS. and is transmitted to the substrate 30. The signal transmitted to the board SOK passes through the hole 12 via the gate 31 and is output to the outside.

At this time, for example, even if a very small amount of glue occurs in the glass tube 17, which is the third space, the area around the glass tube 11 becomes the fourth space 21 that is vacuum-sealed, so The degree of vacuum in the glass tube 17 does not decrease at all, or even if it decreases, the rate of decrease is extremely slow, so the output signal output from the pressure sensitive element 21 is
There is almost no error.

Further, conventionally, a lead wire serving as a medium for outputting to the outside is filled with a pressure transmission medium 25. Although the second space is connected to the outside through the absolute pressure transducer main body 12, in the embodiment of the present invention, the inside of the fourth space 28 is also connected via the substrate JO existing in the fourth space 28. Wired lead wire 3
Since it is connected to the outside via 1, temporarily lead @ 3
Even if I-socket is generated by being drawn into the vacuum of the fourth space 28 from the insulating material surrounding the fourth space 28, there is no adverse effect.

Furthermore, even if a strong impact is applied to the f2 gas tube 11 and the glass tube is destroyed, the differential pressure between the degree of vacuum in the fourth space 28 and the pressure of the fluid to be measured will not be output. Further, the broken glass tube JFIID fragments are scattered only inside the absolute pressure transducer main body 12, but not to the outside, and there is no problem with the absolute pressure transducer.

In this embodiment, high vacuum formation in the third space is performed using heater 1.
The evaporation source 19 was heated and evaporated by the glass tube adsorption r having the component 1a, and the evaporation source 19 was heated and evaporated by the glass tube 18. Needless to say, this is not the only limit.

That is, if the inner surface of the tt glass tube 7 is coated in advance without providing the glass tube suction group 18, and the glass tube LR tube is sealed in a vacuum, the result will be the same as when the glass tube suction group 18 is used. The same effect can be obtained.

Further, although the glass tube 11 is used as the third space in this embodiment, it is also possible to use a material other than the glass tube 1r as long as it can form and maintain a vacuum state.

As detailed above, the absolute pressure transducer according to the present invention includes a first space into which the fluid to be measured flows and a second space in which the pressure transmission medium is accommodated via the seal diaphragm 72,
A third space is isolated from this second space in a vacuum state like S*, and this third space is separated into a fourth space that is also in a vacuum state.
A pressure-sensitive conversion mechanism is interposed between the second space and the third space to sense the differential pressure between the main force of the fluid to be measured and the vacuum pressure in the third space. It is configured to output to.

Even if a leak occurs in the container that forms this third space, the vacuum level will not change because the fourth space has the same degree of vacuum as the third space. There is almost no drop in the output signal, and there is almost no error in the output signal.Also, since the lead wire is wired in the fourth space, even if gas is generated from the insulation material, it will not be sensitive. There is no #i static error in the output signal from the pressure conversion mechanism.
This means that a stable absolute pressure transducer with a long lifespan can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross section showing the configuration of a conventional absolute pressure transducer.
The second section of the figure is a sectional view showing the structure of an absolute pressure transducer as an embodiment of the invention. 16-1f, 1 (D space, 24...second 2 space m, 11.-third wall space, 21.-fourth space, 1
1...Pressure sensitive element (pressure sensitive converter).

Claims (2)

[Claims] (1) A first space into which the fluid to be measured flows;
a second space separated from the space through a seal diaphragm and filled with a pressure transmission medium that transmits the pressure of the fluid to be measured;
, a third space adjacent to the second space and isolated in a true 9 state, and provided to cover the third space and similar to the third space above. a fourth space that is sealed in a vacuum state, and a fourth space that is interposed between the second space and the third space, and that
An absolute pressure transducer characterized by comprising a pressure-sensitive transducer that detects a difference in pressure between the two and outputs an electric signal proportional to the pressure difference to the outside. (2) A patent claim characterized in that, as a means for outputting an electric signal proportional to a pressure difference to the outside, the electric signal is outputted from a pressure-sensitive converter body through a lead wire wired in a fourth space. The absolute pressure transducer according to item 1.