JPH0521008Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal bubble detector that detects air bubbles present in a liquid flowing in a pipe.

[Prior Art] There are three types of conventionally known methods for detecting bubbles present in liquid flowing in a pipe. First, the first method utilizes light transmittance, and detects the difference in transmittance between liquid and bubbles. However, with this method, it is extremely difficult to detect when there is almost no difference in transmittance between the liquid and bubbles, that is, when the liquid is transparent.

The second method is to install two electrodes at appropriate locations in the conduit and pass a current between these electrodes.
Detection is performed based on the difference in electrical conductivity between liquid and bubbles. However, this method cannot measure the difference in electrical conductivity from bubbles with electrically insulating liquids, and cannot be used with liquids that may corrode electrodes.

The third method is to install two electrodes in parallel outside the tube.
The capacitance between these electrodes is measured, and detection is performed by taking advantage of the fact that liquid and gas have different capacitances. However, since the capacitance value actually measured in this method is quite small, it is not suitable for detecting air bubbles in minute parts.

As described above, the conventional techniques are limited by the liquids that can be used, and are difficult to use in minute areas, making it impossible to detect liquids over a wide range.

[Purpose of the invention] The purpose of the invention is to provide a thermal bubble detector that can be used for a wide range of liquids and can detect air bubbles in microscopic areas by eliminating the problems of the conventional method described above. .

[Summary of the invention] The gist of the invention to achieve the above objectives is as follows:
A correction temperature measuring means for detecting the temperature of the liquid flowing in the pipe and performing temperature correction is disposed on the upstream side, and a temperature measuring element dissipates heat into the liquid in the pipe and measures changes in the amount of heat dissipated. A heating type temperature measuring means for detecting the temperature is arranged on the downstream side, and the heating type temperature measuring means has the temperature measuring element built into the tip of the protrusion, and the change in the amount of heat radiation determined by the temperature measuring element is corrected. This thermal bubble detector is characterized in that it detects bubbles in a liquid by correcting them using a temperature measuring means.

[Embodiments of the invention] The invention will be described in detail based on illustrated embodiments.

Figure 1 is a basic configuration diagram of the thermal bubble detector according to the present invention. In principle, a thermal detection method is adopted, and the state of heat radiation from the heating element is different for liquids and gases. I'm taking advantage of that. Inside the flow tube 1, a temperature sensor 2 for temperature correction is installed on the upstream side and an indirect heating type temperature sensor 3 is installed on the downstream side at appropriate intervals. After contacting the correction temperature sensor 2, the indirect heating type temperature sensor 3 is contacted. As shown in FIG. 2, the indirect heating type temperature sensor 3 has a heating element 3 such as a heater inside the wall of the distal end of a protective tube 3a made of ceramic or the like.
b is a temperature measuring element 3 such as a thermistor inside the protection tube 3a.
It has a built-in c. This indirect heating type temperature measuring sensor 3 radiates heat to the liquid in the flow tube 1 by means of a heating element 3b, and detects a change in the state of heat radiation by means of a temperature measuring element 3c. The state of heat radiation from the heating element 3b of the indirect temperature sensor 3 not only differs depending on whether the surroundings are liquid or gas, but also changes depending on the temperature of the liquid flowing in the flow tube 2. 2 detects the temperature of the liquid flowing in the flow tube 1 in order to correct for changes in temperature of the liquid.

Based on the outputs from these two temperature sensors 2 and 3, the bubbles A existing in the flow tube 1 can be detected. That is, when the bubble A contacts the indirect temperature sensor 3, the amount of heat released by the temperature sensor 3 decreases, and the temperature sensor 3c can detect that the temperature at the tip increases.

Since this thermal bubble detector utilizes heat radiation, it can be detected regardless of the color or electrical conductivity of the liquid, and can be used for a wide range of liquids. However, in the configuration shown in FIG. 1, if the diameter of the flow tube 1 is too large, the bubbles A may pass through the indirectly heated temperature sensor 3 without contacting it. Even if the temperature sensor 3 is made larger according to the size, if the bubble A is small, detection is difficult because the contact area with the temperature sensor 3 is a small proportion of the entire surface area of the temperature sensor 3.

Figure 3 shows that in order to solve this problem, the flow tube 1 at the sensor installation part is made thinner, for example, to an inner diameter of about 2 mm, so that the air bubbles A can spread to the entire inside of the flow tube 1, and it is used as a heated temperature sensor. A self-heating type temperature sensor 13 is used, and has a structure in which a tip part has a thin protrusion shape, a temperature measurement element 13c which also serves as a heating element is installed there, and the entire body is sealed with glass or the like. Note that since the correction temperature sensor 12 only detects the temperature of the liquid, it is only necessary to seal the temperature measurement element 12c with glass.

In this way, the self-heating temperature sensor 13
Since the air bubbles A always come into contact with the heating element consisting of the temperature measuring element 13c, the air bubbles A can be detected. In addition, since the part of the temperature measuring element 13c at the tip is thin and protruding, the temperature measuring element 13c is always completely covered with the bubbles A when the bubble A passes, so that the responsiveness is good and the minute bubbles A Highly accurate detection is also possible for. Furthermore, since the base is thick, a commercially available mounting unit can be used to attach it to the flow tube 1, making the attachment work easy.

[Effects of the invention] As explained above, the thermal bubble detector according to the invention takes advantage of the fact that the amount of heat dissipated is different between gas and liquid. It is possible to measure a wide range of liquids with high precision without being subject to the limitations of

[Brief description of the drawings]

The drawings show an embodiment of the thermal bubble detector according to the present invention, in which Fig. 1 is a basic configuration diagram, Fig. 2 is a sectional view of an indirectly heated temperature sensor, and Fig. 3 is a diagram of another embodiment. FIG. 1 is a flow tube, 2 is a correction temperature sensor, 3 is an indirect heating type temperature sensor, 3a is a protection tube, 3b is a heating element,
3c, 12c, and 13c are temperature measuring elements, and 13 is a self-heating temperature sensor.

Claims (1)

[Claims for Utility Model Registration] 1. A correction temperature measuring means for detecting the temperature of the liquid flowing in the pipe and correcting the temperature is disposed on the upstream side, and dissipates heat to the liquid in the pipe. A heating type temperature measuring means for detecting a change in the amount of heat dissipated by a temperature measuring element is arranged on the downstream side, and the heating type temperature measuring means has the temperature measuring element built in the tip of the protrusion, and the temperature is measured by the temperature measuring element. 1. A thermal bubble detector, characterized in that air bubbles in a liquid are detected by correcting a change in the amount of heat dissipated by the correction temperature measurement means. 2. The thermal bubble detector according to claim 1, wherein the heating type temperature measuring means has a temperature measuring element used for both purposes of generating heat and measuring temperature. 3. The thermal bubble detector according to claim 1, wherein the heating type temperature measuring means is sealed with glass. 4. The thermal bubble detector according to claim 1, wherein the temperature measuring element is a thermistor.