JPH03200032A - 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 more particularly to a pressure sensor with small hysteresis during pressure increase and decrease.

[Conventional technology and its problems]

The diaphragm type pressure sensor will be described with reference to FIG.
The pressure receiving chamber 2 is connected to the introduction pipe 4 for the pressure-detected fluid a, and the backup chamber 3 is divided into a
The diaphragm D is provided with a ram 5 that contacts the center of the diaphragm D and is movable in its axial direction, and a spring 6 that biases the ram toward the diaphragm D side. The deflection of D 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 have disclosed the
As shown in the figure, a wavy cross section exhibiting spiral ripples P from any point around the center circle 10 of the material plate,
We proposed that the spiral ripples P be inclined toward the central circle (see Fig. 3). 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 a disc spring in which the spiral ripple is formed around at least three times, and the convex side is backed up. The ram is interposed in the compartment facing the chamber, and the disc spring is reversed by moving the ram so that its convex surface faces the pressure receiving chamber.

The spiral ripple may be one or more than one ripple, and in the case of multiple ripples, the starting point is equally distributed around the central circle.

The inclination of the spiral ripples is shown in FIG. 1
) 5 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.

[Operation] The pressure sensor configured as described above introduces the pressure-detected fluid into the pressure-receiving chamber in the same manner as before, converts the deflection of the diaphragm due to the introduced pressure into movement of the ram, and calculates the amount of movement as follows: Detection is performed using a 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 example is a stainless steel foil hoop 34 amφ with a thickness of 0.015 cm, which is pressed to have a finished outer diameter of 25.4 msφ.

Its front view and cross-sectional view are shown in Fig. 2 and Fig. 3, and in the figures, the pitch d of the spiral ripple P = 0.598 mm, the diameter S of the center circle 10 = 5.0 m++, and the outermost diameter of the ripple P. =20.2mm, curvature of valley and peak r = 0.3m
m, height of ripple P = 0.08 m, height difference between outer periphery and center T = 1.2 mm, curvature R of ripple P portion = 100 m
+ binding, spiral ripples P from the − point around the central circle 10
The wave was formed over 12 times (waves are omitted in Figures 2 and 3).

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 amplifier chamber 3, the adjusting screw 7 is screwed in, and the ram 5 is moved to remove the diaphragm D. Invert it, and make the convex surface the pressure receiving chamber 2 side.

On the other hand, in the conventional example, the diaphragm D was set from the beginning as shown by the solid line (on 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 pressure is increased, and the fist is when the pressure 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 P1 and at a predetermined interval, and between both circular ripples. , the above spiral ripple P
, was formed. Also in the embodiment shown in FIG.
It is also possible to form a configuration in which an outer circular ripple P2 is formed and a spiral ripple P joins the ripple P2.

In each example, the ratio h/j of the inclination height h of the spiral ripple P to the radial length l! was set to 1/6 or less.

〔Effect of the invention〕

Since the present invention is configured as described above, the hysteresis at the time of voltage increase and decrease, especially at the start of voltage increase and at the end of voltage decrease, is reduced, and the detection accuracy of the initial state or 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 is a pressure-displacement measurement diagram, and Figure 6 is a schematic front view of a conventional diaphragm. 1... Casing, 2... Pressure receiving chamber,
3...Backup room, 4...Introduction pipe, 5...Ram,
6...Spring, 10...Central circle, P, P,...Spiral ripple, P,, P2...Circular ripple, D... ...Diaphragm.

Claims (5)

[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, and a ram is connected to its axis. In the pressure sensor, the diaphragm is provided with a spring that biases the ram toward the diaphragm side. and is composed of a disc spring whose spiral ripples are inclined toward the central circle and formed around at least three circumferences, and the disc spring is interposed in both chambers with the convex side facing the backup chamber. A pressure sensor characterized in that the ram is moved to invert the disc spring so that its convex surface faces the pressure receiving chamber. (2) The pressure sensor according to claim (1), wherein the spiral ripple is formed as a single line. (3) The pressure sensor according to claim 1 or 2, wherein the spiral ripples are formed in a plurality of stripes, and the starting point of each spiral ripple P is equally spaced around the central circle. (4) A 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 (
The pressure sensor according to any one of 1) to (3). (5) 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 spiral ripples are formed. A claim characterized in that ripples are formed (
1) The pressure sensor according to any one of (4).