JPH0723251U - Capacitive pressure sensor - Google Patents

Abstract

(57) [Summary] [Structure] The diaphragm 12 fixed to the base 10,
A movable electrode plate 14 arranged substantially parallel to the fixed electrode plate 15 and fixed to the diaphragm, a movable electrode terminal 18 electrically connected to the movable electrode plate and penetrating the base, and a fixed distance from the movable electrode plate. In order to maintain the fixed pin, a fixed electrode plate fixed to the base by a fixed pin 17 via a spacer, and fixed electrode terminals 19 provided electrically connected to the fixed electrode plate are provided. Due to the function of the portion 17a and the elasticity of the fixing pin, the base and the fixed electrode plate are closely fixed to the spacer. [Effect] By fixing the fixed electrode plate to the base through the spacer by the function of the fixing pin, it is possible to provide a capacitance type pressure sensor in which the distance between the fixed electrode plate and the movable electrode plate is stabilized. Becomes

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the structure of a capacitance type pressure sensor used for detecting a pressure change of a fluid.

[0002]

[Prior art]

 The configuration of the conventional capacitance type pressure sensor will be described with reference to the sectional view of FIG.

A diaphragm 22 is fixed by soldering to the upper surface of the base 20 to which the fluid introduction pipe 21 is fixed.

Further, the movable electrode plate 24 is fixed to the diaphragm 22 with solder 23 so that the movable electrode plate 24 is parallel to the fixed electrode plate 25 and has a constant interval, so that the diaphragm 22 and the movable electrode plate 24 are integrated. There is.

A fixed electrode plate 25 is attached to the base 20, a spacer 26 made of an insulating material, for example, a plastic material, a fixing pin 27 penetrating the spacer 26, and a fixing ring 28 for inserting the tip of the fixing pin 27. It is fixed using and. Further, a fixed electrode terminal 29 is connected to the fixed electrode plate 25 by soldering.

On the other hand, the movable electrode terminal 30 is fixed to the base 20 with a set screw. Therefore, the movable electrode terminal 30 maintains electrical connection with the movable electrode plate 24 via the base 20, the diaphragm 22, and the solder 23.

In this pressure sensor, a dimensional change in the space between the fixed electrode plate 25 and the movable electrode plate 24, which is caused by the fluid pressure introduced from the fluid introduction pipe 21 fixed to the base 20, is regarded as a change in the capacitance between the electrodes. Catching. Then, this capacitance change is guided to the measuring circuit by the fixed electrode terminal 29 and the movable electrode terminal 30.

[0008]

[Problems to be solved by the device]

 As described above, the capacitance type pressure sensor captures a dimensional change between electrodes as a capacitance change between electrodes. Therefore, when assembling, the gap between the movable electrode plate 24 and the fixed electrode plate 25 is fixed to a certain value, and it serves as a reference for the dimensional change in the gap between the fixed electrode plate 25 and the movable electrode plate 24 caused by the subsequent pressure change. There must be.

In the electrostatic capacitance type pressure sensor in the prior art, as shown in FIG. 4, the fixed electrode plate 25 is fixed to the base 20 by pressing a fixing ring 28 into the tip of the fixing pin 27. There is.

However, when press-fitting, the fixing pin 27 causes a temporary elastic deformation of compression due to the press-fitting resistance with the fixing ring 28, and there is a phenomenon that the pin is restored by releasing the press-fitting after the completion of the press-fitting operation.

This means that the fixed electrode plate 25 cannot be adhered and fixed to the base 20 through the spacer 26, and the space between the spacer 26 and the fixed electrode plate 25, and between the spacer 26 and the base 20. There is a gap between and. As a result, there is a problem that the gap between the movable electrode plate 24 and the fixed electrode plate 25 at the time of assembly cannot be fixed at a predetermined value.

An object of the present invention is to solve the above problems and provide a capacitance type pressure sensor capable of stably fixing the distance between a fixed electrode plate and a movable electrode plate at a predetermined value. That is.

[0013]

[Means for Solving the Problems]

 In order to achieve the above object, the capacitance type pressure sensor of the present invention adopts the configuration described below.

The capacitance type pressure sensor of the present invention has a diaphragm fixed to the base, a movable electrode plate fixed substantially parallel to the fixed electrode plate and fixed to the diaphragm, and electrically connected to the movable electrode plate. , The fixed electrode plate that is fixed to the movable electrode terminal through the spacer and the fixed electrode plate that is fixed to the base via a spacer to maintain a certain distance from the movable electrode plate. A fixed electrode terminal to be provided is provided, and the base and the fixed electrode plate are closely fixed to the spacer by the action of the inverse taper portions provided at both ends of the fixed pin and the elasticity of the fixed pin.

[0015]

[Action]

 The conventional fixed electrode plate is fixed to the base by pressing the fixing ring into the end of the fixing pin.In the capacitive pressure sensor of the present invention, a spacer is fitted to the center of the fixing pin. In the assembled state, a fixed pin fitted with a spacer is inserted from the side direction into the notched engaging parts on each of the fixed electrode plate and the base.

The inverse taper portions provided at both ends of the fixing pin have a function of restricting the fixed electrode plate and the base from moving away from the spacer, and at the same time, in combination with the elastic force of the fixing pin, the base and the fixed electrode. The plate can be closely fixed to the spacer.

[0017]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a capacitance type pressure sensor of the present invention, and FIG. 2 is a sectional view showing details of a fixing structure of a fixed electrode plate to a base. Further, FIG. 3 is an enlarged plan view showing an engaging portion provided in the base and the fixed electrode plate, in which the fixing pin is housed.

As shown in FIG. 1, a fluid introduction pipe 11 separate from the base 10 is attached by soldering to a center hole provided in the base 10. Further, the diaphragm 12 is soldered to the upper surface of the base 10 at the diaphragm peripheral portion 12a and fixed to the base 10.

The movable electrode plate 14 is fixed to the diaphragm 12 by solder 13 at the respective central positions.

The movable electrode plate 14 is substantially parallel to the fixed electrode plate 15 which is positioned and fixed in a predetermined position by a ring-shaped spacer 16 made of an insulating material, for example, a plastic material, and is movable with the movable electrode plate 14. It is kept at a fixed distance from the fixed electrode plate 15.

In order to fix the fixed electrode plate 15 to the base 10 via the spacer 16, a fixing pin 17 made of, for example, a plastic material having both insulating properties and elasticity is used.

FIG. 2 shows the shape of the fixing pin 17. As shown in FIG. 2, a large diameter portion 17b is provided substantially at the center of the fixing pin 17 in the length direction, and the large diameter portion 17b is fitted into the inner diameter portion of the spacer 16 to determine the position.

A small diameter portion 17c and a reverse taper portion 17a are provided at both ends of the large diameter portion 17b of the fixing pin 17, respectively. Furthermore, a hole 17d is provided in the center of the fixing pin 16 for the purpose of promoting elasticity of the reverse taper portion 17a.

The fixed electrode plate 15 is fixed to the base 10 by first providing the fixed electrode plate 15 and the base 10 shown in FIG. 3 with the spacer 16 fitted in the central portion of the fixed pin 17. This is performed by inserting the fixing pin 17 and the spacer 16 from the side surface into the engaging portion 10a having a partial cutout, which will be described later in detail.

Further, a fixed electrode terminal 19 is fixed to the fixed electrode plate 15 by soldering or welding.

The movable electrode terminal 18 penetrates a hole provided at a position adjacent to the outer peripheral portion of the diaphragm 12 fixed to the base 10, and the hook-shaped portion 18a of the movable electrode terminal 18 is welded to the upper surface of the diaphragm peripheral portion 12a. And is stuck.

This pressure sensor detects a change in the distance between a fixed electrode plate 15 and a movable electrode plate 14 fixed via a solder 13 to a diaphragm 12 that is displaced according to the fluid pressure to be detected. This is regarded as a change in the capacitance between the electrodes of 14 and the fixed electrode plate 15.

Therefore, the fixed electrode plate 15 is connected to the measurement circuit via the fixed electrode terminal 19 electrically connected to the fixed electrode plate 15.

On the other hand, the movable electrode plate 14 is connected to the measuring circuit through the solder 13 fixedly connected to the movable electrode plate 14, the diaphragm 12, and the movable electrode terminal 18.

Details of a method of fixing the fixed electrode plate 15 to the base 10 will be described with reference to FIGS. 2 and 3. Each of the fixed electrode plate 15 and the base 10 is provided with an engaging portion 10a having a notch. The notch forms a locking portion 10b having a size smaller than the diameter formed by the engaging portion 10a.

As described above, the fixing pin 17 made of a material having elasticity has reverse taper parts 17a at both ends, and holes 17d are provided to increase the elastic deformation amount of the reverse taper part 17a. It has a hollow structure. The spacer 16 is preliminarily fitted in the central portion of the fixing pin 17.

The fixed electrode plate 15 and the base 10 are placed in a state in which the respective locking portions 10 b of the fixed electrode 17 and the base 10 are in contact with the upper and lower surfaces of the spacer 16 integrated with the fixing pin 17, and the lateral direction relative to the locking portion 10 b. Then, the fixing pin 17 is inserted.

As a result, the fixing pin 17 having elasticity rides over the locking portion 10b and is housed in the locking portion 10a.

The thickest portion of the inverse taper portion 17 a provided at both ends of the fixed pin 17 is made larger in diameter than the diameter of the fixed electrode plate 15 and the engaging portion 10 a of the base 10. From this, the fixed pin 17 is caught between the fixed electrode plate 17 and the base 10 at a portion of the reverse taper portion 17a having a diameter dimension substantially equal to that of the engaging portion 10a.

The lengthwise distance connecting the engaging portions 10 a at both ends of the fixed pin 17 with a portion having substantially the same diameter is shorter than the distance between the spacer 16 and the fixed electrode plate 17 and the base 10. Set it. As a result, the reverse taper portions 17a at both ends of the fixing pin 17 are elastically deformed and housed in the engaging portion 10a. As a result of this elastic deformation, a force works to press the fixed electrode plate 17 and the base 10 toward the spacer 16.

In the above description, the plastic material is used as the material of the spacer 16. However, by using a material such as ceramic, glass, or ceramics that has a small value in thermal deformation and hygroscopicity, the normal environment and temperature can be improved. It is possible to stabilize the distance between the fixed electrode plate 17 and the movable electrode plate 14 even in an environment where the humidity changes.

[0037]

[Effect of device]

 As described above, according to the present invention, the fixed electrode plate is tightly fixed to the base via the spacer by the action of the fixing pin, so that the fixed electrode plate and the movable electrode plate have a stable gap. It is possible to provide a capacitance type pressure sensor.

[Brief description of drawings]

FIG. 1 is a sectional view showing a capacitance type pressure sensor according to an embodiment of the present invention.

FIG. 2 is a detailed cross-sectional view of a fixed electrode plate fixed to a base according to an embodiment of the present invention.

FIG. 3 is a plan view showing in detail an engaging portion for accommodating a fixing pin provided on a base and a fixed electrode plate according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional capacitance type pressure sensor.

[Explanation of symbols]

 10 base 12 diaphragm 14 movable electrode plate 15 fixed electrode plate 16 spacer 17 fixed pin 18 movable electrode terminal 19 fixed electrode terminal

Claims (1)

[Scope of utility model registration request] 1. A diaphragm fixed to a base, a movable electrode plate arranged substantially parallel to a fixed electrode plate and fixed to the diaphragm, and a movable electrode terminal electrically connected to the movable electrode plate and penetrating the base. And a fixed electrode plate that is fixed to the base by a fixing pin via a spacer in order to keep a constant distance from the movable electrode plate, and a fixed electrode terminal provided electrically connected to the fixed electrode plate. A capacitance type pressure sensor characterized in that the base and the fixed electrode plate are closely attached and fixed to a spacer by the action of the inverse taper portions provided at both ends and the elasticity of the fixing pin.