JPH0630762U - Capacitance sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the assemblability of the capacitance sensor and perform highly accurate detection. [Structure] Two first electrode plates 2 projecting from an abutment surface 22B in the first sensor cylinder 22 from one side in the axial direction to the other side.
4A. 24B is formed. On the other hand, three second electrode plates 26A, 26B, 26C projecting from the abutting surface 23B toward the other side in the axial direction are also formed in the second sensor cylinder 23. By abutting the abutting surfaces 22B and 23B through the insulating seal member 28, the electrode plates 24A to 26C are abutted.
By forming a plurality of capacitance detecting portions having an equal separation distance d therebetween, the assembling of the capacitance sensor is facilitated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a capacitance sensor that is preferably used in an alcohol concentration measuring device that measures, for example, the alcohol concentration in a liquid.

[0002]

[Prior art]

 Here, a conventional capacitance sensor will be described with reference to FIGS. 7 to 9.

In the figure, reference numeral 1 denotes a cylindrical casing that constitutes the outer shape of a capacitance sensor according to the prior art, and a pair of rod-shaped electrode shafts, which will be described later, are formed on both ends of the casing 1 in the radial direction. Insertion holes 1A, 1A into which 2 and 3 are inserted are formed on the upper and lower sides.

Reference numerals 2 and 3 denote rod-shaped electrode shafts. The rod-shaped electrode shafts 2 and 3 are made of a conductive metal material and are inserted into the respective insertion holes 1 A of the casing 1. Further, spacers 4, 4, ... Cut into predetermined dimensions are provided on the outer peripheral side of the rod-shaped electrode shafts 2, 3. Further, one rod-shaped electrode shaft 2 serves as a positive electrode, and the other rod-shaped electrode shaft 3 serves as a negative electrode.

Reference numerals 5 and 5 denote two side electrode plates, each side electrode plate 5 having a through hole 5A formed in one side thereof, and one rod-shaped electrode shaft is provided in each through hole 5A. 2 is inserted and the spacers 4 are provided between the electrode plates 5, so that the electrode plates 5 are spaced apart from each other by a predetermined distance in the radial direction.

Reference numerals 6, 6 and 6 denote other-side electrode plates consisting of three sheets. A through-hole 6 A is formed on the other side of each of the other-side electrode plates 6, and the other-side electrode plate is provided in each of the through-holes 6 A. By inserting the rod-shaped electrode shaft 3 and arranging the spacers 4 between the electrode plates 6, the electrode plates 6 are separated from each other by a predetermined distance, and the electrode plates 6 are radially separated from each other. The positions are different by the distance d. The space formed by each of the electrode plates 5 and 6 is a flow path through which the fluid to be measured circulates in the direction of the arrow.

Reference numerals 7 and 7 denote stepped tubular seal members that provide insulation when the rod-shaped electrode shafts 2 and 3 are provided in the respective insertion holes 1 A of the casing 1.

Further, as shown in FIG. 9, for example, each of the rod-shaped electrode shafts 2 and 3 includes an LC type oscillation circuit 8, an fV conversion circuit 9 and an inverting amplification circuit 10 via a lead wire (not shown). Is connected to the processing circuit.

In the capacitance sensor configured as described above, it can be considered that the four detection units formed by the electrode plates 5 and 6 are equivalently connected in parallel, and each of the electrode plates 5 is , 6 as a flat plate electrode having a large electrode constant K determined by the effective area and the distance d.

When the fluid to be measured flows in the capacitance sensor as shown by the arrow in FIG. 7, the fluid to be measured flows between the electrode plates 5 and 6, and the fluid to be measured is The detection capacitance C determined by the dielectric constant ε and the electrode constant K of the capacitance sensor is output to the oscillation circuit 8.

As a result, the oscillation circuit 8 oscillates the oscillation frequency f based on the detected electrostatic capacitance C, processes the oscillation frequency f by the fV conversion circuit 9 and the inverting amplifier circuit 10, and measures the fluid to be measured. The output voltage V corresponding to the dielectric constant ε of is derived to the outside.

The capacitance sensor configured as described above is combined with a processing circuit to measure, for example, an alcohol concentration measuring device for alcohol concentration in an alcohol-mixed fuel used in an automobile engine, or for a printing machine. It is appropriately used for measuring the concentration of isopropyl alcohol in dampening water.

[0013]

By the way, in the above-mentioned capacitance sensor according to the prior art, the electrode plates 5 and 6 are held by inserting the rod-shaped electrode shafts 2 and 3 into the through holes 5A and 6A, respectively. Since the spacers 4 are only arranged via the spacers 4, the electrode plates 5 and 6 cannot be displaced and the distance d between the electrode plates 5 and 6 cannot be kept constant. The constant K may fluctuate. This causes a problem that the capacitance of the fluid to be measured cannot be accurately detected.

In the manufacturing process of the capacitance sensor, the through holes 5A and 6A of the electrode plates 5 and 6 are assembled to the rod-shaped electrode shafts 2 and 3 with the spacers 4 interposed therebetween. Takes time and reduces productivity.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an electrostatic capacitance sensor that can be easily assembled and can prevent displacement of each electrode plate. I am trying.

[0016]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the configuration of the capacitance sensor adopted by the present invention is composed of a pair of cylindrical bodies in which one side in the axial direction serves as an inflow / outflow port and the other side serves as an abutting surface. First and second sensor cylinders that form a sensor body having a flow path inside by abutting the mating surfaces, and in each of the sensor cylinders, the first sensor cylinder is axially inserted from one side. A plurality of first electrode plates that are formed in the axial direction so as to project from the abutting surface toward the other side and that are formed in multiple layers in the radial direction, and the second sensor cylinder of the sensor cylinders. It is formed in the axial direction so as to project from one side in the axial direction to the other side in the axial direction, and the position is different from the respective first electrode plates of the first sensor cylinder in the radial direction. A plurality of second electrode plates formed in multiple layers and formed between the first electrode plates and the second electrode plates. , Lies in the structure and a plurality of capacitance detection unit that detects the capacitance of the fluid to be measured flowing through the flow path.

Further, it is desirable to dispose an annular insulating seal member between the abutting surfaces of the sensor tubes.

[0018]

[Action]

 With the above configuration, the fluid to be measured that has flowed in from the inlet of the first sensor cylinder flows from one side to the other in the sensor body, and when it flows out from the outlet of the second sensor cylinder, A plurality of capacitance detecting portions formed between each first electrode plate and each second electrode plate detects the capacitance corresponding to the dielectric constant of the fluid to be measured.

Further, by disposing the insulating seal member between the abutting surfaces of the sensor cylinders, the insulation between the sensor cylinders is improved.

[0020]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS.

First, FIGS. 1 to 3 show a first embodiment. It should be noted that, in the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a sensor body of the capacitance sensor according to the present embodiment, and the sensor body 21 is composed of first and second sensor cylinders 22 and 23, which will be described later. A flow path through which the constant fluid flows is formed as shown by the arrow.

Reference numerals 22 and 23 constitute the sensor main body 21, and respectively show first and second sensor cylinders formed of an aluminum material in a cylindrical shape. One side of the first sensor cylinder 22 is an inlet 22A, The other side serves as an abutting surface 22B, one side of the second sensor cylinder 23 serves as an outlet 23A, and the other side serves as an abutting surface 23B.

Reference numerals 24A and 24B denote rectangular first electrode plates formed in multiple layers inside the first sensor cylinder 22, and the base end sides of the first electrode plates 24A and 24B are the first sensor cylinders. 22 is fixed to an electrode plate support portion 25 formed on the inlet 22A side at a predetermined distance in the radial direction, and the tip end side is directed from the electrode plate support portion 25 toward the other side in the axial direction. They are extended in parallel so as to project from the mating surface 22B.

Further, the electrode supporting portion 25 is provided with rectangular flow path holes 25A, 25A, ... Except for the base end sides of the first electrode plates 24A, 24B.

Reference numerals 26A, 26B and 26C denote rectangular second electrode plates formed in multiple layers inside the second sensor cylinder 23, and the base end sides of the second electrode plates 26A, 26B and 26C are the second electrode plates. The electrode plate supporting portion 27 formed on the outlet 23A side of the sensor cylinder 23 is spaced apart at a predetermined radial position different from the radial distance between the first electrode plates 24A and 24B. The tip ends are fixed in parallel with each other so as to extend from the electrode plate support portion 27 toward the other side in the axial direction and project from the abutting surface 23B.

Further, in the electrode supporting portion 27, rectangular flow path holes 27A, 27A, ... Are formed except for the base end sides of the second electrode plates 26A, 26B, 26C.

Reference numeral 28 denotes an insulating seal member formed in an annular shape from an insulating resin material such as polytetrafluoroethylene. The insulating seal member 28 is the abutting surface 22B of each of the first and second sensor cylinders 22 and 23. , 23B to insulate the first and second sensor cylinders 22 and 23 from each other.

Reference numerals 29, 29, ... Show electrostatic capacitance detection units, and the electrostatic capacitance detection units 29 abut against the abutting surfaces 22B and 23B of the sensor cylinders 22 and 23, respectively. The first electrode plates 24A, 24B and the second electrode plates 26A, 26B, 26C are formed with a separation distance d therebetween. It can be considered that the respective capacitance detection units 29 are equivalently connected in parallel, and the capacitance detection units 29 of the first sensor cylinder 22 and the second sensor cylinder 23 are connected to each other. A detection signal obtained by summing the capacitances is derived.

Reference numeral 30 denotes a resin mold, which is formed by abutting the abutting surfaces 22 B and 23 B of the first sensor cylinder 22 and the second sensor cylinder 23 via an insulating seal member 28. By covering the sensor body 21 from the outside, the sensor cylinders 22 and 23 are fixed.

The capacitance sensor according to the present embodiment has the above-described configuration, and is equivalent to a parallel plate type electrode having an electrode constant K in which four detection units are equivalently connected in parallel as in the prior art. Composed. The detection operation using the capacitance sensor can be performed in the same manner as the detection operation shown in FIG. 9 of the conventional technique.

However, in the capacitance sensor according to the present embodiment, the first electrode plates 24A, 24B and the second electrode plates 26A, 26B, 26C are connected to the sensor tubes 22, 23 via the electrode plate supporting portions 25, 27. Since they are fixed, it is possible to prevent the distance between the electrode plates 24A to 26C from easily changing. Then, by preventing the deviation of the separation distance d between the electrode plates 24A to 26C, it is possible to prevent the electrode constant from changing, reduce the detection error of the detection capacitance of the fluid to be measured, and perform highly accurate detection. Can be done.

Further, in the assembly of the capacitance sensor according to the present embodiment, as shown in FIG. 3, the abutting surfaces of the first sensor cylinder 22 and the second sensor cylinder 23 are separated by the insulating seal member 28. By forming 22B and 23B by abutting against each other, it is possible to easily assemble a capacitance sensor having four capacitance detection units 29 having the same distance d between the electrode plates 24A to 26C. .

Therefore, the process of assembling the capacitance sensor can be simplified, and the productivity can be significantly improved.

Next, a second embodiment according to the present invention will be described with reference to FIGS. 4 and 5. A feature of this embodiment is that a positioning portion that determines a mounting position is formed on each abutting surface of the first sensor cylinder and the second sensor cylinder.

In the embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 31 indicates a sensor main body of the capacitance sensor according to the present embodiment, and the sensor main body 31 is composed of first and second sensor cylinders 22 and 23, in which the fluid to be measured is contained. A flow path that circulates as shown by an arrow is formed.

Here, the abutting surfaces 22B and 23B of the sensor cylinders 22 and 23 of the sensor body 31 are provided with positioning portions 32, which will be described later, for restricting relative rotation of the sensor cylinders 22 and 23. .

Reference numerals 32 and 32 denote the positioning members according to the present embodiment, and each positioning member 32 is formed in a plurality in a radial direction on the outer peripheral surface of the abutting surface 22 B of the first sensor cylinder 22. , And the engaging projections axially protruding in the radial direction of the outer peripheral surface of the abutment surface 23B of the second sensor cylinder 23 so as to engage with the respective recesses 32A. 32B, 32B, ..., And they are adapted to be fitted in a cage.

Reference numeral 33 denotes an annular insulating seal member formed in substantially the same manner as the insulating seal member 28 described in the above-mentioned first embodiment. The insulating seal member 33 is a member of the positioning members 32. Recesses 33A, 33A are formed at predetermined radial positions so as to insulate the mating recess 32A and the engaging protrusion 32B from each other.

Although the capacitance sensor according to the present embodiment is configured as described above, the operation and effect thereof are the same as those of the first embodiment described above.

However, in the present embodiment, since the first sensor cylinder 22 and the second sensor cylinder 23 are restricted in rotation by the positioning member 32, they are formed in the first sensor cylinder 22. The distance d between the first electrode plates 24A, 24B and the second electrode plates 26A, 26B, 26C formed on the second sensor cylinder 23 can be accurately set, and the variation of the electrode constant in each assembly process can be improved. Therefore, the productivity of the capacitance sensor can be significantly improved as compared with the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that the surface of each sensor cylinder made of an aluminum material is anodized so as to have an insulating property, and the insulating seal member is eliminated.

The constituent elements in this embodiment are the same as the constituent elements in the first embodiment described above, but the alumite-treated members will not be described by adding dashes (').

However, in this embodiment, the surfaces of the first sensor cylinder 22 and the second sensor cylinder 23 described in the first embodiment are anodized so that the surfaces are covered with the insulating film S. The sensor cylinders 22 'and 23' are formed. When the sensor body 21 is formed by abutting and combining the abutting surfaces 22B 'and 23B', the insulating film S is formed on the abutting surfaces 22B 'and 23B' by alumite treatment. Therefore, the abutting can be achieved without using the insulating seal member 28 as described in the first embodiment, and the assembling property of the sensor can be further improved as compared with the first embodiment.

In the third embodiment as well, the positioning member as described in the second embodiment may be formed.

Further, in each of the above-described embodiments, after the first sensor cylinder 22 and the second sensor cylinder 23 are abutted against each other to form the sensor main body, the outer circumference of the sensor main body is covered with the resin mold 30 so that the electrostatic charge is generated. Although the capacitance sensor is formed, the present invention is not limited to fixing the sensor cylinders 22 and 23 to the resin mold 30. Even if the sensor cylinders 22 and 23 are fixed by an adhesive agent or the like, the abutment may be performed. A flange portion may be formed on the outer periphery of the surfaces 22B and 23B, and each flange portion may be fixed with a bolt, a nut or the like.

[0048]

[Effect of device]

 As described above in detail, according to the present invention, a sensor body having a flow passage inside is formed by abutting the abutting surfaces of the first and second sensor tubes, and the first sensor tube is provided. Inside, a plurality of first electrode plates are formed in multiple layers in the radial direction so as to extend in the axial direction from one side in the axial direction to the other side and project from the abutting surface. Inside, there are a plurality of axially extending ones in the axial direction so as to project from the abutting surface to the other side, and are arranged at different positions in the radial direction from the first electrode plates of the first sensor cylinder. By forming a plurality of second electrode plates in multiple layers and abutting the abutting surfaces of the respective sensor cylinders, a plurality of capacitance detecting units are formed between the first electrode plates and the second electrode plates. With this configuration, when the fluid to be measured flows through each of the capacitance detectors, the detection signal corresponding to the dielectric constant in the fluid to be measured is detected. It can be taken out. Further, by assembling the abutting surfaces of the sensor cylinders into abutment with each other, the capacitance detecting portion can be formed by the electrode plates, and the capacitance sensor can be easily manufactured.

Further, by disposing the insulating seal member between the abutting surfaces of the sensor cylinders, the insulation between the sensor cylinders can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a capacitance sensor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view as seen from the direction of arrows II-II in FIG.

FIG. 3 is an exploded perspective view of the capacitance sensor according to the present embodiment.

FIG. 4 is a vertical sectional view of a capacitance sensor according to a second embodiment of the present invention.

5 is an enlarged cross-sectional view seen from the direction of the arrow V-V in FIG.

FIG. 6 is a vertical sectional view of a capacitance sensor according to a third embodiment of the present invention.

FIG. 7 is a vertical sectional view of a capacitance sensor according to a conventional technique.

8 is a cross-sectional view as seen from the direction of arrows VIII-VIII in FIG. 7.

FIG. 9 is a block diagram showing a processing circuit using a capacitance sensor.

[Explanation of symbols]

 21 Sensor Main Body 22 First Sensor Cylinder 23 Second Sensor Cylinder 24A, 24B First Electrode Plate 26A, 26B, 26C Second Electrode Plate 28 Insulation Seal Member 29 Capacitance Detection Section S Insulation Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Masahiko Shimamura 167-1 Kasukawa-cho, Isesaki-shi, Gunma Nippon Electric Equipment Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A sensor comprising a pair of cylindrical bodies, one side of which in the axial direction serves as an outflow inlet and the other side thereof serves as an abutting surface, and the inside of which serves as a flow path by abutting the abutting surfaces of each other. The first and second sensor cylinders that form the main body, and of the respective sensor cylinders, are formed in the first sensor cylinder in the axial direction so as to project from one side in the axial direction toward the other side and from the abutting surface. And a plurality of first electrode plates formed in multiple layers in the radial direction, and of the sensor cylinders, the second sensor cylinders project from the abutting surface toward one side in the axial direction toward the other side. So as to be formed in the axial direction, and in the radial direction each of the first sensor cylinders
Formed between each of the first electrode plates and each of the second electrode plates by abutting the abutting surfaces of the plurality of second electrode plates, which are formed in multiple layers at different positions from the electrode plates, with each other. And a plurality of capacitance detecting units for detecting the capacitance of the fluid to be measured flowing in the flow path. 2. The capacitance sensor according to claim 1, wherein an annular insulating seal member is provided between the abutting surfaces of the respective sensor tubes.