JPH03200030A - Pressure sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure sensor, and in particular to a pressure sensor with small hysteresis during pressure increase and pressure decrease.

[Conventional technology and its problems]

The diaphragm type pressure sensor will be described with reference to FIG. 1. The inside of a casing 1 is divided into a pressure receiving chamber 2 and a bank-up chamber 3 by a diaphragm D, and an introduction pipe 4 for the pressure-detected fluid a is inserted into the pressure receiving chamber 2. The back amplifier chamber 3 is provided with a ram 5 that contacts the center of the diaphragm D so as to be movable in the axial direction thereof, and a spring 6 that biases the ram toward the diaphragm D side. The deflection of the diaphragm D due to the introduction pressure of the fluid a is converted into movement of the ram 5, and the amount of movement is detected by a differential transformer, optical sensor, laser sensor, etc.

As the diaphragm D of this pressure sensor, the inventors of the present application disclosed in Japanese Patent Application No. 63-99143, etc.
As shown in Figure 3, a wave cross section exhibiting spiral ripples P is formed from any point around the center circle 10 of the material plate, and the spiral ripples P are inclined toward the center circle. suggested something. Note that the ripples P in the figure indicate the locus of the trough (the same applies hereinafter).

This diaphragm D was set with the convex outer surface facing the pressure receiving chamber 2 as shown by the solid line in Fig. 1, and a pressure-displacement curve was obtained. This was not possible (see conventional example in Figure 4, broken line).

An object of the present invention is to reduce the above hysteresis.

[Means to solve the problem]

In order to solve the above problems, in the present invention, in the diaphragm type pressure sensor, the spiral ripple diaphragm is interposed in both chambers with the convex side facing the back amplifier chamber, and the ram is moved. The convex surface of the disc spring was turned over so that the convex surface faced the pressure receiving chamber.

The inclination of the spiral ripples is shown in FIG. 1
When it is 75 or more, when press forming, with current technology,
This is because the molding pressure differs greatly between the outward facing slope and the inward facing slope, making manufacturing impossible.

In addition, if concentric circular ripples and outer circular ripples are provided, when the ripples are press-formed, the raised distortion that occurs in the center will be absorbed and dispersed in the concentric circular ripples, and the wrinkled distortion that occurs on the outer periphery will be absorbed and dispersed in the outer circular ripples. absorbed and dispersed. This absorption and dispersion becomes more effective if the beginning and end of the spiral ripples merge into the hundred circular ripples.

[Effect]

In the pressure sensor configured in this way, the pressure-detected fluid is introduced into the pressure receiving chamber, the deflection of the diaphragm due to the introduced pressure is converted into movement of the ram, and the amount of movement is determined by the differential transformer. , optical sensor, laser sensor, etc.

During this action, the diaphragm is reversed and detection is made by the deflection of the reversed state, resulting in small hysteresis in boosting and lowering the pressure.

[Example 1] First, the diaphragm D will be explained.

The diaphragm D of this embodiment is made of a hoop 34a*φ of stainless steel foil having a thickness of 70.015 mm and is pressed to have a finished outer diameter of 25.4 mmφ.

Its front view and cross-sectional view are shown in FIGS. 2 and 3. In these figures, the central circle 10 is 5 mm in diameter, and the curvature of the valley part of the spiral ripple P shown in FIG. The curvature r' is 1.O
m, spiral ripples P are formed adjacent to each other from the Mikasa quartile of the central circle 10, and the height t of the waves is 0.3 on.
, the height difference T between the outer periphery and the center is 1.5 mm, and the curvature R is 10
It was set to 0m.

Two pieces of this diaphragm D were manufactured, and each was set in the aforementioned pressure sensor shown in FIG.

In the present invention, as shown by the chain line in the same figure, first, the diaphragm D is interposed with the convex side facing the bank-up chamber 3, the adjusting screw 7 is screwed in, and the ram 5 is moved to remove the diaphragm D. It is turned over, and its convex surface faces the pressure receiving chamber 2 as shown by the solid line in the figure.

On the other hand, in the conventional example, the diaphragm D was set from the beginning as shown by the solid line (in the convex side in the normal state or in the pressure receiving chamber).

FIG. 4 shows pressure-displacement curves for this embodiment and the conventional example. In the figure, the solid line is the example, the broken line is the conventional example, O is when the voltage is increased, and . is when the voltage is decreased. From this, it can be seen that the example has smaller hysteresis when boosting and lowering the voltage, particularly at the start of increasing the voltage and at the end of decreasing the voltage, compared to the conventional example.

Various shapes of the diaphragm D can be considered, such as those shown in FIG. In FIG. 5, concentric circular ripples P1 are formed adjacent to the center circle 10, and outer circular ripples P2 are formed concentrically with this concentric circular ripple P and at a predetermined interval, and both diagonal wave diaphragms are formed. The above-mentioned spiral ripple P3 is formed in the amount. In the embodiment shown in FIG. 2 as well, an outer circular ripple P2 may be formed and a spiral ripple P may be added to the ripple P2.

In each practical example, the ratio h71 of the slope height h of the spiral ripple P to the radial length l was set to be 1/6 or less.

[Effects of the Invention] Since the present invention is configured as described above, the hysteresis at the time of pressure increase and decrease, particularly at the start of the pressure increase and the end of the pressure decrease, is reduced, and the detection accuracy of the initial state or the final state is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the pressure sensor according to the present invention, FIGS. 2 and 5 are schematic front views of each side of the diaphragm, and FIG. 3 is a sectional view of the example of FIG. Figure 4 shows the pressure-displacement measurements. 1... Casing, 2... Pressure receiving chamber,
3...Bank up chamber, 4...Introduction pipe, 5...Ram,
6...Spring, 10...Central circle, P, P3...Spiral ripple, P, ,P,...Circular ripple, D... ...Diaphragm.

Claims (3)

[Claims] (1) The inside of the casing is divided into a pressure receiving chamber and a backup chamber by a diaphragm, an inlet pipe for the pressure-detected fluid is connected to the pressure receiving chamber, and a ram that abuts the center of the diaphragm is connected to the backup chamber with its axis. In the pressure sensor, the diaphragm has a wavy cross-section exhibiting spiral ripples from any point around the center circle of the material plate. The disc spring is formed by a disc spring whose spiral ripples are inclined toward the central circle. A pressure sensor characterized in that the spring is inverted so that its convex surface faces the pressure receiving chamber. (2) Claim characterized in that the ratio h/l of the inclination height h and the radial length l of the spiral ripple is 1/5 or less (
1) The pressure sensor described. (3) Concentric circular ripples are formed adjacent to the center circle of the material plate, and outer circular ripples are formed concentrically with the concentric circular ripples at a predetermined interval, and between both circular ripples, the above-mentioned spiral ripples are formed. A claim characterized in that ripples are formed (
The pressure sensor described in 1) or (2).