JPS6070329A - Pressure transmitting device - Google Patents

Abstract

PURPOSE:To avoid the effect of temperature even though constituent members are changed due to the change in ambient temperature, by forming symmetrical right and left pressure detecting chambers at the central part of a body, and forming two pressure actuating chambers having the same shape at both sides. CONSTITUTION:A pressure transmitting device 1 has a structure having symmetrical right and left parts. A movable electrode 3 comprising a thick plate spring is provided at the central part of a body 2. Symmetrical right and left pressure detecting chambers 2a are formed at the central part of the body 2 by a flange 3a of the movable electrode 3. Recesses, whose diameters are the same as those of communicating paths 2b and 2c are formed in both attachments 7 and 8. Thus a pressure acting chamber 7a on the process side and a pressure acting chamber 8a on the atmospheric side are formed. In this constitution, even though the constituent members are changed due to the change in ambient temperature, the deformations are offset at the right and left sides, and the effect of the temperature can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a capacitive pressure transmitter.

(B) Prior Art Conventionally, as shown in Fig. 1, a pressure transmitter has a flange b attached to one side of a body a by bolts C.
A communication passage d is formed through this body a on both sides, and a disk-shaped pressure detection chamber e is formed in the centrifugal direction from this communication passage d, while a pressure conversion chamber f is formed on one side of the body a. b, an atmospheric pressure working chamber g is formed on one side, a thick plate spring h is provided in the pressure conversion chamber f, a corrugated seal diaphragm i is provided in the atmospheric pressure working chamber g, and this spring h and the seal diaphragm There is one in which silicone oil j is sealed throughout the pressure detection chamber e and the like. Furthermore, on both sides of the spring h, there are rods ff
are connected, one rod k passes through the communication path d, a movable electrode m located in the pressure detection chamber e is attached, and the other rod β faces the pressure action chamber fl formed in the flange b, and the diaphragm 0 A fixed electrode p is provided in the pressure detection chamber e.

Accordingly, process pressure or the like acts on the pressure chamber n, pressing the rod β, bending the thick plate spring h, and moving one of the rods k. This movement causes the movable electrode m to displace, and the gap between it and the fixed electrode p changes, and the capacitance change due to this gap change is derived as a detection signal.

However, this pressure transmitter has a left-right asymmetric structure for reasons such as versatility. That is, a thick plate spring h is provided at the introduction part of the measurement pressure, and the deflection of the spring h is temporarily converted. This poses a problem in that when the ambient temperature, process temperature, etc. change, the displacement due to expansion of the constituent members differs between the atmospheric pressure side and the process side, making them susceptible to temperature effects. Moreover, because atmospheric pressure is transmitted through silicone oil, it is greatly affected by temperature changes.
Measurement reliability was low.

Further, since the thick plate spring h is fixed by the flange b, the structure is complicated.

(c) Purpose This invention was made in view of the above points, and it uses a thick plate spring in combination with the movable electrode and provides it in the center, making the whole structure bilaterally symmetrical, and at the same time canceling out the displacement caused by temperature effects on the left and right sides. The object of the present invention is to provide a pressure transmitter with a simplified structure.

(d) Structure In order to achieve the above-mentioned object, this invention has a pressure detection chamber with a bilaterally symmetrical shape in the center of the body, and two communicating passages of the same shape extending from this pressure detection chamber toward both sides. At the same time, two pressure acting chambers of the same shape are formed on both sides, and a symmetrical movable electrode made of a thick plate spring is provided in the center of the pressure detection chamber, and fixed electrodes are provided on the sides, respectively. Two rods of the same shape are arranged sideways in the center of this movable electrode, and these rods pass through the communication path, and their tip faces face the pressure acting chamber and are configured as pressure receiving surfaces. A seal diaphragm is stretched between the body and the pressure detection chamber, and the pressure detection chamber is configured to have the same pressure on both sides of the movable electrode, and the movable electrode is configured to be displaced by the pressure acting on the pressure receiving surface. ing.

(E) Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

As shown in FIG. 2, numeral 1 is a pressure transmitter, which detects pressures in various processes using changes in capacitance.

This pressure transmitter 1 has a bilaterally symmetrical structure, and a movable electrode 3 made of a thick plate spring is provided in the center of a body 2, and a symmetrical pressure detection chamber is formed in the center of the body 2 by a flange 3a of the movable electrode 3. 2a is formed and configured.

The movable electrode 3 is composed of a flat plate spring with a groove (=J) and has a symmetrical shape, and a fixed electrode 4 facing the movable electrode 3 is attached to the side surface of the pressure detection chamber 2a via an insulator 5. , lead wires 6 are connected to both electrodes 3.4, respectively.

Two communication passages 2b and 2C are bored in the body 2 from the pressure detection chamber 2a toward both sides, and the double-speed passages 2b and 2c are formed in the same shape. Furthermore, attachments 7.8 are fitted and fixed in the recesses on both sides of the body 2. Both axotiments 7.8 include the communication path 2b,
2C and a recess having the same diameter as the communication passages 2b and 2c is formed to constitute a process-side pressure action chamber 7a and an atmosphere-side pressure action chamber 8a. This attachment 7 on the process side slightly protrudes from the body 2, and a pressure introduction passage 7C is formed from the pressure action chamber 7a via a passage 7b.
The attachment 8 on the atmosphere side is formed flush with the body 2, and the pressure chamber 8a is open to the atmosphere via a passage 8b. The buried portions of the body 2 of both axotiments 7.8 are formed to have the same shape, and the pressure measuring chambers 7a, 8a and the passages 7b, 8b have the same shape.

Two rods 9 and 10 are provided at the center of both sides of the movable electrode 3.
are arranged side by side. Both rods 9 and 10 are formed in the same shape, pass through each of the communication passages 2b and 2c, and have pressure receiving surfaces 9a and loa with their tip faces facing the pressure acting chambers 7a and 8a, so that process pressure and atmospheric pressure act on them. It is supposed to be done.

Further, a guyafram 11 is stretched between the tip of the rod 9.10 and the body 2, and a pressure action 37.8 is partitioned, and a communication passage 7.8 and a pressure detection chamber 2a are sealed. An inert gas 12 (for example, nitrogen gas) is sealed therein. Further, a bypass passage 13 is formed between both rods 9 and 10 passing through the movable electrode 3, so that both sides of the movable electrode 3 communicate with each other and are configured to have the same pressure.

Next, the pressure detection operation will be explained.

First, the process pressure is
It acts on the pressure action chamber 7a through the passage 7b, and on the other hand,
Atmospheric pressure acts on the pressure chamber 8a via the passage 8b of the axotiment 8. Each pressure acts on the end pressure receiving surfaces 9a, 10a of the rod 9.10, pressing the rod 9.10 inward.

This process pressure is converted into movement of the rod 9 from the pressure receiving surface 9a and transmitted to the movable electrode 3. Since this movable electrode is composed of a thick plate spring, it will be bent by the process pressure, and this displacement will change the gap with the fixed electrode 4, and the capacitance change due to this gap change will be reflected via the lead wire 6. and transmit it as a detection signal.

In this pressure transmitter 1, the ambient temperature changes.

However, since the structure is bilaterally symmetrical, the displacement of each component is the same on the left and right sides and cancels out, resulting in almost no temperature influence.

In addition, the inert gas 12 protects both electrodes 3.4,
Moreover, even if a temperature change occurs, the movable electrode 3 is not affected at all because it moves via the bypass path 13.

In this embodiment, one of the pressure chambers 8a is opened to atmospheric pressure, but another process pressure may be introduced to detect the differential pressure. That is, the process pressure may be introduced by replacing the atmospheric side axotiment 8 shown in FIG. 2 with the same axotiment 14 as the process side axotiment 7.

Furthermore, although it is not necessarily necessary to enclose the inert gas 12 in view of the operation of the movable electrode 3 and the like, it is preferable to enclose the inert gas 12 in order to protect the electrodes 3.4.

Further, the bypass path 13 is not limited to the embodiment as long as both sides of the movable electrode 3 can be connected to each other.

(f) Effects As described above, according to the pressure transmitter of this invention, the entire structure is symmetrical, so even if the surrounding temperature changes and each component changes, it will be canceled out on the left and right sides. Temperature effects can be eliminated.

Further, since a thick plate spring and a movable electrode are used in combination and installed at the center, there is no need to provide a flange as in the conventional case, and the structure can be extremely simplified.

[Brief explanation of drawings]

FIG. 1 is a central longitudinal cross-sectional view showing a conventional pressure transmitter, and FIG. 2 is a central cross-sectional view of a pressure transmitter according to an embodiment of the present invention. 1: Pressure transmitter, 2: Body, 2a: Pressure detection chamber, 1b-2c: Communication path, 3: Movable electrode, 4: Fixed electrode, 7, 8, 14: Axotiment, 7a, 8a: Pressure action chamber, 9/10: Rod, 9a/1
0a: Pressure-receiving surface, 11: Daitoflam, 12: Inert gas, 13: Bypass path Patent applicant Shimadzu Corporation Representative Patent attorney Shigeru Nakamura

Claims (2)

[Claims] (1) A symmetrical pressure detection chamber is located in the center of the body.
Two communication passages of the same shape are formed from this pressure detection chamber toward both sides, and two pressure acting chambers of the same shape are formed on both sides, and left and right pressure chambers made of thick plate springs are formed in the center of the pressure detection chamber. A movable electrode with a symmetrical shape is provided with a fixed electrode on each side, and two rods of the same shape are connected laterally at the center of the movable electrode. is configured as a pressure receiving surface facing the pressure action chamber, and a seal diaphragm is provided between the tip and the body, while the pressure detection chamber is configured to have the same pressure on both sides of the movable electrode, and the pressure detection chamber is configured to have the same pressure on both sides of the movable electrode. A pressure transmitter characterized in that a movable electrode is displaced by pressure acting on a pressure receiving surface. (2) The pressure transmitter according to claim 1, wherein a high detected pressure acts on one of the pressure acting chambers, and atmospheric pressure acts on the other.