JPS59166829A - Electrostatic capacity type pressure sensor provided with adjusting means - Google Patents

Abstract

PURPOSE:To make a titled sensor inexpensive without requiring an especially high accuracy for working of a parts, and also to simplify an assembling operation by dividing a fixed electrode into plural pieces, and also constituting so that a fixed position to a housing of a fixed electrode supporting member can be adjusted in accordance with said each division. CONSTITUTION:When three sets of capacities consist of a movable electrode 6 and fixed electrodes 8a, 8b and 8c connected to a capacity measuring instrument or an oscillator, and a frequency measuring instrument, and pressure is applied to a diaphragm 5 from a pressure inlet 1b, the three sets of capacities become an almost equal value if each electrode is parallel. Also, if there is an inclination between each electrode, the three sets of capacities become unbalance. Accordingly, when the three sets of capacities are unbalanced, any of nuts 13a, 13b and 13c is rotated, seeing the measuring instrument, so as to detect a state that the three sets of capacities become alsmot equal, by which each electrode is set to a parallel state. Also, it is possible to adjust an inter-electrode distance in case there is no pressure, by moving in parallel a state that each electrode is set in parallel, and a variation of each sensor can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitive pressure sensor equipped with adjustment means.

In a capacitive pressure sensor, the parallelism of the movable electrode and fixed electrode during zero machining affects the detection accuracy during pressurization, and in order to maintain that parallelism, high precision machining of each part is required. However, it also had the disadvantage that it required skill to assemble.

In view of the above-mentioned conventional drawbacks, an object of the present invention is to make it possible to set the parallelism of the fixed electrode to the movable electrode.
It is an object of the present invention to provide a capacitive pressure sensor equipped with an adjusting means that allows adjustment of the fixed position of a fixed electrode support member with respect to a housing.

Hereinafter, the present invention will be explained in detail based on the drawings.

In FIGS. 1 and 2, ] is a plastic housing that forms an annular groove 1a and a pressure force 1b in the lateral direction, that is, in the direction perpendicular to the direction of pressure applied to the diaphragm, which will be described later. However, the size in the height direction has been reduced.

2 i 0 +). Reference numeral 3 denotes a base member made of a metal material, which is fixed to the housing 1 with a metal screw 4, and is pressed between the O-ring 2 and the housing 1. A metal diaphragm 5 made of phosphor bronze, for example, is fixed to the base member 3 by soldering, and still supports the movable electrode 6 by soldering. 7 is a fixed electrode support member made of glass epoxy or ceramic material;
On the side facing the movable electrode 6, fixed electrodes 82.degree. 8-b and 8c divided into three fan-shaped parts are supported, and on the opposite side, another fixed electrode 9 is supported, respectively. 10a, ]Ob and (]O
c) They are screwed into the housing 1 at equal intervals and supported by locking screws and locking screws. 11a.

11b and llc are plastic screws, and the fixed electrode 8a
, 8b and 8c, at equal intervals on the periphery of the fixed electrode support member 7, respectively.
, 12. It is supported by plastic screws 10a, 10b and (10c), and is formed to have a reverse thread. 13a.

(13b and 13c) are the original plastic nuts,
Plastic screws 10a lla respectively.

10b-11b and (10c)-11c.

As shown in the figure, the movable electrode 6 and the fixed electrodes 8 a and '8 b
When three sets of capacitances according to 8c and 8c are connected to a capacitance measuring device or an oscillator and a frequency measuring device and pressure is applied to the diaphragm 5 from the pressure force 1b, the capacitances of the three sets are approximately equal if the electrodes are parallel to each other. value.

Furthermore, if there is a slope between the electrodes, the capacitance of the three sets will be unbalanced.

Therefore, when the capacities of the three sets are unbalanced, by rotating either nut 13a, (13b and 13C) while looking at the measuring instrument, and finding a state in which the capacities of the three sets are approximately equal, each This is because the electrodes are set in a parallel state.

Furthermore, by moving the parallel electrodes in parallel, the distance between the electrodes during zero machining can be adjusted, and variations among individual sensors can be corrected.

Note that the number of divisions of the fixed electrode (8) is not limited to three, but may be any suitable number such as two or four or more.

The capacitance of the fixed electrode 9 and the fixed electrodes 8a, 8b, and 8c is set so that the stray capacitance of the sensor body can be canceled out within the detection circuit.

As described above, in the capacitive pressure sensor of the present invention, the parallelism between the fixed electrode and the movable electrode can be adjusted, so high precision is not required for processing the parts, and the yield is low. This not only makes it possible to reduce costs, but also simplifies assembly work.

A high quality and uniform pressure sensor can be obtained through this simple adjustment work.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a pressure sensor according to the present invention, and FIG. 2 is a bottom view taken along the line ■-■ in FIG. 1... -Housing 3... Base member 5 - Diaphragm 6...... Movable, electrode 7...
・・・・・・・・・Fixed electrode support member (8) ・・
......Fixed electrode (10), (1+,
)...screws (12), (13)... Nando patent applicant

Claims (2)

[Claims] (1) In a capacitive pressure sensor comprising a diaphragm that supports a movable electrode and is fixed to a housing, and a fixed electrode support member that supports a fixed electrode facing the movable electrode and is fixed to the housing, the fixed The electrode is divided into a plurality of parts, and in order to set the parallelism of each divided fixed electrode with respect to the movable electrode, the fixed position of the fixed electrode support member with respect to the housing can be adjusted in accordance with each division. A capacitive pressure sensor equipped with an adjustment means characterized by: (2) The means for adjusting the fixed position of the fixed electrode support member with respect to the housing is formed by a screw protruding from the support member side, a screw protruding from the housing side, and a reverse screw rotation mechanism screwed into both screws. A capacitive pressure sensor comprising the adjusting means according to claim 1.