JPS5945930B2 - Pressure-displacement conversion mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanism for converting pressure into displacement.

More specifically, the invention relates to a mechanism that converts fluid pressure into displacement using a bellows.

The mechanism for converting pressure into displacement is as shown in Fig.
-38206 (JP 54-128779) There is a pressure conversion mechanism.

In FIG. 1, 1 is a bellow into which input pressure is introduced; 2.
Reference numeral 3 designates bellow ends each having a circular disk shape, which are fixed to both ends of the bellows 1, respectively.

Reference numeral 4 denotes a connecting plate made of a plate-shaped elastic material, which is slightly eccentric (in this example, by e) from the central axis of the bellows, and is fixed to the bellow end 2 at one end and to the bellow end 3 at the other end.

5 is a base to which bellow end 3 is fixed.

Reference numeral 6 denotes an inlet, and input pressure Pin is introduced into the bellows 1 through this hole.

In such a device, when input pressure Pin is introduced into the bellows 1, a force corresponding to the effective area of the bellows 1 is generated in the axial direction of the bellows 1.

This force tends to push the bellows 1 off in the axial direction, but since the bellow ends 2 and 3 are connected to each other eccentrically from the axis by the connecting plate 4, the bellow ends 2 are located approximately at the center of the connecting plate 4. Tilt eccentrically with respect to the axis using one point as a fulcrum.

By utilizing the displacement caused by this inclination, a pressure→displacement conversion mechanism can be obtained.

Now, if the angle of inclination of the bellows is θ, the relationship with the input pressure Pin will be as shown in the following equation.

-e θζ□・Pin Kf 1KB However, θ: Output inclination angle A: Effective area of bellows 1 e: Eccentricity Kf: Rotation spring constant of connecting plate 4 KB: Rotation spring constant of bellows 1 Pin: Input pressure In the bellows 1, the bellow ends 2 and 3 are connected by a connecting plate 4 eccentrically from the central axis of the bellows 1, so that a fulcrum is formed at a central point on the bellows connecting plate 4, that is, Since the fulcrum can be placed inside the bellows 1, the overall configuration can be simplified and the device can be made inexpensive and compact.

However, the linearity is poor due to the pressure curve displacement angle characteristics and characteristics as shown in FIG.

This is because the effective area of the bellows 1 decreases as the output asperity angle θ increases.

The reduction in effective area of the bellows can be ignored at minute displacements.

However, it is generally known that when the diaphragm is displaced, the effective area decreases.

Since the bellows can be said to be a stack of diaphragms, if the displacement becomes large or if high accuracy is an issue, the effect of a reduction in the effective area must be taken into consideration.

The present invention solves this problem.

An object of the present invention is to provide a pressure-displacement converting mechanism that has a simple configuration, has good accuracy, is inexpensive, and can be miniaturized.

The present invention will be explained below with reference to the drawings.

FIG. 3 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 1 represent the same functions.

Reference numeral 4 denotes a connecting plate made of a plate-shaped elastic material and having a convex arc shape in the direction of the central axis of the bellows 1.

The connecting plate 4 is slightly eccentric (by e in this embodiment) from the central axis of the bellows 1, and is fixed to the bellow end 2 at one end and to the bellow end 3 at the other end.

This connecting plate 4 bends in the axial direction of the bellows 1 when the input pressure Pin is introduced into the bellows 1 and the internal pressure increases.

As a result, the curvature of the arcuate portion becomes smaller, and the bending moment applied to the connecting plate increases.

That is, as shown in FIG. 4A, in the conventional example shown in FIG. Equally, −F−e.

On the other hand, as shown in FIG. 4B, in this embodiment, the bending moment M acting on the convex portion of the connecting plate 4 is smaller than that in the conventional example shown in FIG. 4A. .

That is, the connecting plate 4 is bent.

Next, when the curvature of the convex portion of the connecting plate 4 decreases due to the force F, the bending moment M acting on the connecting plate 4 increases by 7 parts as shown in FIG. 4C.

That is, the connecting plate 4 is easily bent.

Therefore, if the effective area of the bellows 1 is now constant, the pressure-displacement angle characteristic has a characteristic as shown in FIG. 5 in which the differential coefficient increases as the input pressure Pin increases.

Therefore, the characteristics due to changes in the effective area of bellows 1 (=
(Fig. 2), as shown in Fig. 6, the change (decrease) in the effective area A of the bellows 1 is corrected, and a pressure-displacement conversion mechanism with small nonlinearity and high precision is obtained. be able to.

Therefore, for the various bellows used, the shape of the curve of the connecting plate 4, the material of the connecting plate 4, the cross-sectional shape of the connecting plate 4, etc. are appropriately selected so as to compensate for the characteristics of changes in the effective area. By this, the overall nonlinearity is small,
You can obtain high precision.

As explained above, according to the present invention, accuracy is good and
It is possible to realize a pressure-displacement conversion mechanism that is inexpensive and compact.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of the device of Japanese Patent Application No. 53-38206, FIG. 2 is an explanatory diagram of the characteristics of FIG. 1, FIG. 3 is an explanatory diagram of the configuration of an embodiment of the present invention, and FIGS. 4A, B, C1 FIG. 5 is an explanatory diagram of the operation of FIG. 3, and FIG. 6 is an explanatory diagram of the characteristics of FIG. 3. 1... bellows, 2, 3... bellow end, 4...
connecting plate.

Claims (1)

[Claims] 1. A pressure-displacement conversion mechanism comprising a bellows and a connecting plate that connects both ends of the bellows at positions eccentric from the central axis of the bellows within the bellows and has a convex curved shape in the direction of the central axis.