JP5349759B2 - Liquid detection sensor - Google Patents

Description

The present invention relates to a technique for determining a state of a liquid flowing through a liquid distribution tube and quality of the liquid tube.

  A beverage manufacturer sends a manufactured beverage to a storage container or a transport container through a tube, and at a restaurant or a medical site, the beverage or chemical is taken out from the container every time it is used through the tube. In order to detect the state in the tube such as running out of liquid, a transparent tube is often used, but it is difficult to always observe visually. For this reason, various devices related to an apparatus for detecting a state such as a liquid shortage in the tube have been proposed.

  There has been proposed a liquid shortage sensor that installs a pair of electrodes in a tube and determines the presence or absence of liquid (Patent Document 1). In addition, a liquid shortage sensor using a difference in the refractive index of light depending on the presence or absence of liquid has been proposed (Patent Documents 2 and 3). In addition, a photosensor using a difference in the amount of received light depending on the presence or absence of a circulating liquid by providing a photosensor including a light emitting portion and a light receiving portion with a tube interposed therebetween is proposed (Patent Document 4).

JP 2000-170663 A JP 2004-045319 A JP 2006-10597 A Japanese Patent Laid-Open No. 2003-248812

  However, the sensor in which the electrode is installed in the pipe has problems in terms of hygiene and safety in order to be used for beverages and medical liquids in addition to the problem of sensitivity reduction due to electrode corrosion and wear. Therefore, in order to use for a wide range of applications, an apparatus that detects a state such as running out of liquid without contacting the internal liquid is desirable.

  In addition, the liquid breakage sensor that uses the difference in the refractive index of light depending on the presence or absence of the liquid changes the light receiving position depending on the diameter of the tube and the type of the liquid. There are problems such as complicated device settings and increased costs, such as complicated calculations and adjustment tools.

  A photosensor using the difference in the amount of received light can easily detect the presence or absence of liquid in the tube without contact. However, it is not sufficient to distinguish between the case where the liquid is fully distributed and the case where the liquid is not distributed at all. The liquid does not always circulate in the same state, but may be foamed due to a lack of liquid volume, and foreign matter may be mixed in. In addition, although there is no shortage of liquid, bubbles may be generated instantaneously. It must be able to appropriately determine such various internal states. Further, the photosensor is provided with a connecting portion made of a light transmissive tube having a photosensor separately from the front and rear pipes in the middle of the liquid supply path, and there is a problem that the apparatus is complicated.

  The present invention has been made in view of such circumstances, and provides a detection sensor for accurately and quickly detecting the internal state of the liquid flowing through the tube and the quality of the liquid distribution tube, the provision of a device for displaying the internal state, and an abnormality. An object of the present invention is to provide a liquid abnormality alarm device that issues an alarm in the case of a state.

In addition to the case where the liquid is filled in the flow tube or the case where the liquid is completely drained, there are cases where bubbles are generated, foreign matters are mixed, and the like. In addition to the presence or absence of liquid, the transparency of the tube may decrease due to long-term use. The level of the amount of light received by the light receiving element changes depending on these situations.
Various internal states can be detected by sorting the level of the amount of received light by the signal processing unit. In the prior art, the presence of bubbles was regarded as noise for determining the presence or absence of liquid, but in the present invention, bubbles are detected based on the amount of received light, and the presence of bubbles itself is a sign of liquid shortage and insufficient gas pressure. It has become possible to use it as influential information inside the equal circulation liquid.

That is, more to the present invention, there is provided a liquid detection sensor consisting of a light projecting element light receiving element and a signal processing unit, the light emitting element is disposed outside of the fluid transfer tube, the light receiving element is emitted from the light projecting element light disposed outside of the fluid transfer tube facing the light projecting element for receiving, the signal processing unit on the basis of the number of times of the change in the per fluctuation range and units of the received light amount time for measuring the time axis of the light receiving element , the liquid detection sensor, wherein the it is capable of detecting the presence or absence of air bubbles flowing through the liquid flow in the tube is provided.
When the liquid and gas are mixed due to bubbles, etc., the amount of received light changes drastically, and when the normal amount of received light is stable, the amount of fluctuation in the amount of received light with respect to the measurement time axis and the number of fluctuations per unit time Are very different. By detecting the fluctuation state of the amount of received light, the internal state such as the generation of bubbles can be determined very accurately.

  If there are multiple light receiving elements, there will be a difference in the amount of light received between the light receiving element facing the front of the light projecting element and the light receiving element located outside the front. Therefore, the degree of difference in the amount of received light is different. Therefore, by detecting this difference, it is possible to determine the presence or absence of the circulating fluid. The same applies when there are a plurality of light projecting elements.

Oite the present invention, the is either the light emitting element and the light receiving element is provided with a plurality groups, a plurality of sets distribution in the longitudinal direction of the opposing pair of light projecting element and the light receiving element is the fluid transfer tube It is preferable to be provided.

Using the liquid detection sensor of the present invention, it is possible to determine the presence or absence of a liquid and the identification of the liquid (for example, beer or orange juice). Further, it can be determined whether the replacement time has arrived due to the tube becoming old based on the level of the amount of received light. On the wall of the old tube, it is easy for foreign matter to adhere and molds to propagate. As a result, the liquid quality is lowered, and there is a possibility that problems such as liquid leakage due to quality deterioration may occur. It becomes possible to do. Furthermore, the presence of bubbles and foreign matters can be detected by mixing a large number of different values within a certain time.

By using the liquid detection sensor of the present invention , it is possible to quickly grasp the generation of bubbles. The generation of bubbles may be in a stage before running out of liquid, or may be due to insufficient gas pressure. By grasping these pieces of information at an early stage, it becomes possible to thoroughly prevent the liquid from running out or to prevent the supply of foamy beer due to insufficient gas pressure in advance.

In the liquid detection sensor of the present invention , by installing a plurality of sets of detection sensors, it is possible to more quickly grasp the generation of bubbles that were missed by only one detection sensor. On the contrary, for a very small amount of bubbles that are generated regardless of the liquid running out, the plurality of detection sensors hardly detect the bubbles at the same time. In such a case, malfunctions such as running out of liquid can be prevented by comprehensively judging. Moreover, the flow rate of the liquid can be measured by analyzing the time difference between the detection sensors capturing the tip of the bubble. By grasping the flow velocity, it is possible to predict the time from bubble generation to liquid breakage.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of a liquid detection device according to the present invention. FIG. 1A shows a state where the liquid detection sensor housing 9 is closed and attached to the liquid circulation tube 1. An LED 10 and a switch 11 are incorporated on the outer surface of the housing, and a DC power source is used as a power source. FIG. 1B shows a state where the liquid detection sensor housing is opened. The light projecting element 3 and the light receiving element 4 are fitted inside the casing, and when the casing is closed, the light projecting element and the light receiving element are opposed to each other with the liquid circulation tube interposed therebetween. The light receiving element is connected to a signal processing unit 13 (not shown). The signal processing unit includes amplification of received light signals and filters.

  FIG. 3A is a cross-sectional view of a state in which the liquid detection sensor according to the present invention is set in a liquid circulation tube. The light projecting element 3 projects light to the opposing light receiving element 4 through the flow tube 1. As the light projecting element, an LED is preferable from the viewpoint of lifetime, but is not limited thereto. As the projection wavelength, infrared light of 800 to 1000 nm is used. The light receiving element is preferably a photodiode, but is not limited thereto. FIG. 3A shows the state of the air 2a when the tube is not filled with liquid. FIG. 3-1 (b) shows a state where the tube is filled with a liquid 2b such as beer. FIG. 3C shows a state where the tube is filled with a liquid such as beer and the liquid circulation tube 5 is dirty.

  FIG. 3B is a conceptual diagram illustrating an irradiation state of the projected infrared light in FIG. When infrared light projected from the light projecting element 3 is received by the light receiving element, if the inside of the flow tube is air (gas), it diffuses due to the difference in refractive index between the liquid and the gas, so the amount of light received by the light receiving element Is relatively low. On the other hand, when the distribution tube is filled with a liquid such as beer, the light projection is not diffused so much that the amount of light received by the light receiving element becomes relatively high. When the flow tube is dirty, the projection light is shielded and scattered in the tube, so that the amount of light received by the light receiving element is relatively lower than when the tube is clean. When bubbles are generated or foreign substances are mixed, the level of the amount of received light changes depending on the internal state.

In a state where bubbles are generated in the beer, the liquid-filled state and the empty state are mixed and vigorously switched. For this reason, the level of the amount of received light varies drastically with respect to unit time. By analyzing the fluctuation rate of the amount of received light, it is possible to grasp the generation of bubbles more reliably. The variation rate of the amount of received light is determined by processing the light reception signal of the light receiving element by the signal processing unit. In addition to the determination based on the received light amount level, it is more preferable that the determination based on the variation rate of the received light amount is combined to be determined by the signal processing unit, which directly leads to a quick and accurate determination.

  FIG. 4 is a conceptual diagram of the amount of light received by the light receiving element. In FIG. 4, when the liquid is filled in the flow tube, the amount of received light is the highest in 16b. When there is no liquid in the flow tube, the amount of received light is the lowest in 16a. In the case where the liquid is filled in the flow tube but the tube is dirty, in 16c, the amount of received light shows an intermediate value. Accordingly, if threshold values 6 and 7 are set between the received light amount values, three states can be determined.

  The signal about the presence / absence of liquid, the presence / absence of foreign matter, the presence / absence of bubbles, and dirt on the tube determined by the signal processing unit is displayed on a display unit (not shown). For example, when beer is properly distributed, the green LED lights up. When the tube is dirty, the orange light turns on. If it is, red is lit, and if there is a sign of running out of liquid or the state of liquid is bad due to the presence of bubbles or foreign matter, the state can be clearly displayed by blinking green.

  The determination process of the control unit may use a microcomputer, or a simple comparator or logic circuit. In addition, a signal can be sent from the control unit to a display unit installed at a remote place via a communication device. Also, the alarm device operates in conjunction with the display unit. For example, when the tube is empty due to beer liquid running out, the alarm buzzer can be sounded simultaneously with the red light on the display unit.

  FIG. 2 shows a second embodiment. While there are one light projecting element, two light receiving elements are provided, and three units constitute a set of liquid detection sensors. The light receiving element 4 is opposed to the front surface of the light projecting element 3, while the light receiving element 12 is opposed to the longitudinal direction of the liquid flow tube while being displaced. Each light receiving element is connected to the signal processing unit 13. The signal processing unit is connected to the LED 10, and is further connected to the output contact 14 and the external output terminal 15. As the external output, it is possible to use a contact / non-contact output such as a relay or a semiconductor, or a communication means with an external device. Further, the output unit may be configured wirelessly using wireless or the like. Although the power supply of the apparatus is not particularly shown, it is possible to connect a power supply line from the outside or to drive a battery.

  As described with reference to FIG. 3B, the light projected from the light projecting element diffuses when the liquid is not filled as shown in FIG. The difference in the amount of received light is relatively small. On the other hand, when the liquid is filled as shown in FIG. 2B, it does not diffuse so much, so that the amount of light received by the front light receiving element 4 becomes relatively large. Therefore, the difference in the amount of light received between the light receiving element 4 and the light receiving element 12 is increased. Thus, the state of the liquid in the liquid circulation tube can also be grasped by analyzing the difference in the amount of light received between the light receiving element located in front of the light projecting element and the light receiving element located away from the front.

  FIG. 5 shows a third embodiment. There are three light projecting elements and three light receiving elements, respectively, which are arranged apart in the length direction in the liquid circulation tube. The light projecting elements 3a, 3b, and 3c are opposed to the light receiving elements 4a, 4b, and 4c to constitute one set of liquid detection sensors, respectively, and constitute a total of three sets of liquid detection sensors. The light projecting element and the light receiving element are arranged on the substrate 8, and the light receiving element is connected to the signal processing unit 13. (Not shown)

  Each set of liquid detection sensor elements receives the received light amount level such as the presence or absence of liquid in the tube and the received light amount fluctuation rate, and the contents thereof are determined by the signal processing unit. Since each set of liquid detection sensors maintains a certain distance, it is possible to independently grasp the situation of the liquid in the flow tube passing through the front of each position. Therefore, not only information on one point such as liquid, but also a wide range of a certain range can be grasped, and a specific situation upstream of the liquid grasped by one set of liquid detection sensors is downstream after a certain time. A set of liquid detection sensors located on the side can be grasped. For this reason, it becomes possible to prevent a detection omission, to prevent an excessive reaction and malfunction due to only a part of the situation, and to grasp the spread of bubbles and the like. In addition, it is possible to perform analysis such as measuring the liquid flow velocity by analyzing the time difference between each pair of liquid detection sensors for grasping the head position of bubbles or the like passing through the front.

  Next, a description will be given based on experimental data. The experiment was conducted using two sets of liquid detection sensors each using an LED as a light projecting element and one photodiode as a light receiving element. Both the light projecting element and the light receiving element were disposed at positions facing each other by 1 mm from the outer surface of the liquid circulation tube. As the liquid distribution tube, a nylon tube having an outer shape of 10 mm and a wall thickness of 2.5 mm was used. The infrared light of 950 nm was projected from the light projecting element, and the value with respect to the time axis (ms) of the amount of light received by the light receiving element was plotted. The amount of received light is expressed by dividing 5v by N and N is a digital value.

  FIG. 7 shows received light amount values when the tube is empty. The digital value is in the vicinity of 256 to 300 and is stable. FIG. 8 shows the received light amount value when the inside of the tube is filled with beer. The digital value is around 1 to 2, and it is stable. It is shown that the amount of light received is much higher than the empty state because the beer, which is a liquid, fills the tube. FIG. 9 shows a state where the tube is filled with beer and the tube is dirty. The tube was cloudy and used when it was time to replace. The digital value shows around 64, and it is still stable. It is considered that the light reception amount value is lower than the numerical value of FIG. 8 due to the high light shielding property of the tube.

FIG. 10 shows received light amount values in a state where the light receiving element is shielded from light. Measurement was performed with the casing of the liquid detection sensor opened at an angle at which the projected light was not received by the light receiving element. The digital value stably indicates around 512. FIG. 11 shows the amount of received light in a state where bubbles are generated. The digital value fluctuates violently around 64 to 500. When bubbles are generated, the received light amount level itself changes, but the rate of change is much larger than in other states. Therefore, it is possible to differentiate from other states by the fluctuation rate.
When attention is paid to the time difference between the first axis and the second axis in FIG. 11, the delay which was about 100 msec at the start of recording extends to 300 msec at the end, and gradually during this measurement. It can be judged that the flow rate of the beer in the tube has dropped. Thus, the time difference between the optical axes can be easily measured and used.

  FIG. 12 shows the amount of received light when the tube is filled with soy sauce. The digital values are almost the same as in the case of beer. FIG. 13 shows the amount of light received when 23% orange juice is filled in the tube and FIG. 14 shows the state where 100% orange juice is filled. In the case of 23% orange juice, the vicinity is around 64, and in the case of 100% orange juice, the vicinity is around 400. The reason why the amount of light received is smaller than in the case of beer and soy sauce is presumed to be because orange absorbs near-infrared light. In the case of 100% orange juice, since the absorbance is higher, the amount of light received by the light receiving element is lower than when the liquid circulation tube is empty. As described above, it is possible to identify the circulating liquid by the amount of received light and discover the mixture of liquids by utilizing the light absorbency of the liquid.

  According to the present invention, since it is possible to accurately grasp the internal state such as the presence or absence of liquid flowing in the tube such as beer and the generation of bubbles, it becomes possible to detect liquid breakage, foreign matter contamination and the like at an early stage. Moreover, it is possible to respond quickly based on the grasped information. The present invention is not limited to liquids in general and is a technology that can be used in a wide range of gases.

It is a block diagram of the housing | casing incorporating a liquid detection sensor. It is a block diagram of the liquid detection sensor of a mode with one light projecting element and two light receiving elements. It is a block diagram of a liquid detection sensor. It is a block diagram regarding light reception and light projection of a liquid detection sensor. It is explanatory drawing regarding a light reception level. It is a block diagram of the liquid detection sensor which consists of 3 sets of light projection elements and a light receiving element. It is explanatory drawing regarding the light reception amount transition at the time of bubble generation | occurrence | production. It is a light reception amount transition data figure of the state where the liquid distribution tube is empty. It is a light reception amount transition data figure of the state with which the inside of a liquid distribution tube is filled with beer. It is a light reception amount transition data figure of the state where the inside of a liquid distribution tube is filled with beer, and a distribution tube is dirty. It is a light reception amount transition data figure in the state where the light receiving element is shielded from light. It is a light reception amount transition data figure in the state where the bubble has occurred in beer in a liquid distribution tube. It is a light reception amount transition data figure of the state with which the inside of a liquid distribution tube is filled with soy sauce. It is a light reception amount transition data figure of the state with which the inside of a liquid distribution tube is filled with 23% orange juice. It is a light reception amount transition data figure of the state with which the inside of a liquid distribution tube is filled with 100% orange juice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid distribution tube 2a Air in liquid distribution tube 2b Liquid in liquid distribution tube 3a-3c Light emitting element 4a-4c Light receiving element 5 Tube dirt 6 Presence / absence of liquid in the tube and determination threshold 7 Tube dirt Judgment threshold value 8 Substrate 9 Case 10 LED
DESCRIPTION OF SYMBOLS 11 Switch 12 Light receiving element 13 Signal processing part 14 Output contact 15 External output terminal 16a Transmittance when there is no liquid in a liquid distribution tube 16b Transmittance when the liquid distribution tube is filled with liquid 16c In a liquid distribution tube Is filled with liquid, but the transmittance when the tube is dirty 16d Transmittance when the liquid flowing through the tube contains bubbles or foreign matter

Claims (2)

A liquid detection sensor comprising a light projecting element, a light receiving element, and a signal processing unit, wherein the light projecting element is disposed outside a liquid circulation tube, and the light receiving element receives the light emitted from the light projecting element. The liquid processing tube is disposed outside the liquid circulation tube facing the optical element, and the signal processing unit moves the inside of the liquid circulation tube based on the fluctuation range of the amount of received light with respect to the measurement time axis of the light receiving element and the number of fluctuations per unit time. A liquid detection sensor capable of detecting the presence or absence of circulating bubbles.   A plurality of the light projecting elements and the light receiving elements are provided, and a plurality of sets of the light projecting elements and the light receiving elements facing each other are arranged in the length direction of the liquid circulation tube. The liquid detection sensor according to claim 1.