JPH05142185A - Bubble detection sensor - Google Patents

Abstract

PURPOSE:To detect any bubbles most sensitively in a noncontact manner and without using light by detecting the bubbles existing in liquid between electrodes as the output changes of ceramic resonance means. CONSTITUTION:A detection sensor 1 consists of a detection section 10, an oscillation circuit 2, a ceramic resonance circuit 3 and an AM detecting and amplifying circuit 4. The section 10 is composed of a resin pipe 11 filled with a liquid W, and a ground electrode 12 and active electrode 13 interposing the pipe 11. The electrode 12 is a plate electrode connected to the ground. While, the electrode 13 is a plate electrode connected to the circuit 3. Then the electrostatic capacity between the electrodes 12 and 13 varies as a bubble B passes through the liquid W. That is, when the bubble passes through between the electrodes 12 and 13, the bubble detection signal will vary only at that moment, so that the presence of the bubble B can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bubble detection sensor, and more particularly to a bubble detection sensor capable of detecting bubbles in a liquid with high sensitivity.

[0002]

2. Description of the Related Art Conventionally, various sensors have been proposed, but a sensor capable of detecting air bubbles in a liquid with high sensitivity without contact and no light is not known.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bubble detection sensor capable of detecting bubbles in a liquid with high sensitivity without contact and without light.

[0004]

A bubble detection sensor of the present invention comprises at least a pair of electrodes that allow liquid to be present between them, and ceramic resonance means for changing resonance characteristics according to changes in capacitance between the electrodes. And a reference oscillating means for inputting a drive signal of a reference frequency to the ceramic resonance means, and detecting bubbles in the liquid existing between the electrodes as a change in the output of the ceramic resonance means. It is what

[0005]

The ceramic resonance means has the resonance characteristic that the output signal has a steep peak at a certain frequency (resonance frequency) of the input signal. When air bubbles are mixed in the liquid existing between the electrodes, the capacitance between the electrodes changes, and the resonance characteristic of the ceramic resonance means changes. Therefore, if a reference frequency signal that is slightly deviated from the resonance frequency is input from the reference oscillating means to the ceramic resonance means, the resonance characteristics change when bubbles are mixed in the liquid existing between the electrodes. The output of the means changes sharply.

Therefore, it is possible to detect air bubbles in the liquid existing between the electrodes with high sensitivity without contact and without light.

[0007]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. However, this does not limit the present invention. FIG. 1 is a configuration diagram of a bubble detection sensor 1 according to an embodiment of the present invention. This bubble detection sensor 1
Is composed of a detection unit 10, an oscillation circuit 2, a ceramic resonance circuit 3, and an AM detection amplification circuit 4.

As shown in FIG. 2 (a sectional view taken along the line AA 'in FIG. 1), the detection unit 10 is a resin pipe 1 filled with a liquid W.
1 and a ground electrode 12 and an active electrode 13 sandwiching the resin pipe 11. The ground electrode 12 is a plate electrode connected to the ground. The active electrode 13 is a plate electrode connected to the ceramic resonance circuit 3. Ground electrode 12 and active electrode 1
The capacitance between 3 is different between the state in which the resin pipe 11 is filled with only the liquid W and the state in which the bubbles B are mixed. That is, when the bubble B passes through the liquid W, the capacitance changes.

The oscillator circuit 2 is constructed by using a ceramic resonator 2a. The oscillation frequency is, for example, 1 GHz. This is output as a drive signal of the reference frequency from the amplifier 2b.

The ceramic resonance circuit 3 is constructed by using a ceramic resonator 3a and has a high Q resonance characteristic. The resonance characteristic shifts as shown in FIG. 3 due to the change in the capacitance between the ground electrode 12 and the active electrode 13. Therefore, the amplitude of the signal output with respect to the drive signal of the reference frequency input from the oscillation circuit 2 changes.

The AM detection amplification circuit 4 extracts a change in the amplitude of the signal output from the ceramic resonance circuit 3 by the detection circuit 4a and outputs it as a bubble detection signal from the amplification circuit 4b.

In the bubble detection sensor 1 described above, when the bubble B passes between the ground electrode 12 and the active electrode 13, the bubble detection signal changes only at that time, so that the bubble B can be detected. Further, the size of bubbles can be estimated from the size of the peak of the bubble detection signal, and the number of bubbles can be estimated from the number of peaks.

As another embodiment, there is one in which the detecting section 20 of FIG. 4 is used instead of the detecting section 10 of FIG.
The detection unit 20 uses a ground electrode 22 and an active electrode 23 that are formed in a curved shape that matches the outer peripheral surface of the resin pipe 11. In the detection unit 20, the ground electrode 22 and the active electrode 23 are fixed in close contact with the resin pipe 11, so that the average distance between the electrodes becomes small and the detection S / N ratio can be increased. ..

As still another embodiment, there is one in which the detecting section 30 of FIG. 5 is used instead of the detecting section 10 of FIG. The detection unit 30 has ground electrodes 32a and 32b formed in a curved shape that matches the outer peripheral surface of the resin pipe 11.
And the active electrodes 33a and 33b are used.

In this detector 30, there are a plurality of pairs of ground electrodes 22 and active electrodes 23, and the resin pipe 1
Since it is fixed in close contact with No. 1, the S / N ratio for detection can be increased.

[0016]

According to the bubble detection sensor of the present invention, bubbles in a liquid can be detected with high sensitivity without contact and no light. For example, bubble detection for operating control of a washing machine or automatic Foam detection for cooking control in cooking equipment, foam detection for sudden prediction in chemical reactors, foam detection for process control of sludge treatment facilities, and compressor operation control It is useful for bubble detection and bubble detection for monitoring primary tubules.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a bubble detection sensor of the present invention.

FIG. 2 is a sectional view taken along the line A-A ′ in FIG.

FIG. 3 is a resonance characteristic diagram of a ceramic resonance circuit.

FIG. 4 is a cross-sectional view showing the structure of a detection unit in another embodiment of the bubble detection sensor of the present invention.

FIG. 5 is a cross-sectional view showing the structure of a detection unit in still another embodiment of the bubble detection sensor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bubble detection sensor 2 Oscillation circuit 3 Ceramic resonance circuit 10 Detection part 11 Resin pipe 12 Ground electrode 13 Active electrode 20 Detection part 22 Ground electrode 23 Active electrode 30 Detection part 32a, 32b Ground electrode 33a, 33b Active electrode

Claims (1)

[Claims] 1. At least a pair of electrodes in which a liquid can be present, ceramic resonance means for changing resonance characteristics according to a change in capacitance between the electrodes, and a drive signal of a reference frequency for the ceramic resonance means. A bubble detection sensor comprising a reference oscillating means for inputting and detecting bubbles in the liquid existing between the electrodes as a change in the output of the ceramic resonance means.