JP2000266584A - Illuminance difference detection type level gage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminance difference detection type level gage which enables relatively easy and direct measurement of the liquid surface in a storage tank difficult in direction measurement. SOLUTION: This illuminance difference detection type level gage has an optical fiber 4a for illumination and first and second fibers 4b and 4c for reception and the first and second fibers 4b and 4c for reception are made different in height. Light irradiated from the side of the lower end of the optical fiber 4a for illumination is received as scattered reflected light from the liquid surface from the side of the lower ends of the first and second optical fibers 4b and 4c for reception. The scattered reflected light is trapped by a photocell 6 on the side of the upper ends of the first and second optical fibers 4b and 4c for reception therethrough to monitor the illuminance difference with an illuminance difference gage 7. The light reception end as lower end side of the optical fiber 4b for reception is determined to reach the liquid surface by detecting the illuminance difference with the illuminance difference gage 7. Thus, the position of the liquid surface is calculated from the graduation in a stainless wire 8 and the drawing of a storage tank 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminance difference detection type liquid level meter capable of relatively directly measuring a liquid level in a storage tank which is difficult to measure directly.

[0002]

2. Description of the Related Art For example, calibration of a liquid level gauge installed in a storage tank for an ultra-low temperature liquid or the like is performed by using a portable level gauge because there is no portable liquid level gauge capable of directly measuring the liquid level of the stored liquid. In various indirect ways depending on the situation. It is difficult to directly measure the liquid level of the stored liquid, for example, because liquid nitrogen has a boiling point of -194 ° C, the wall surface of the storage tank is made of a thick material, and has a double structure for heat insulation. ing. For this reason, the liquid level cannot be seen from the outside of the storage tank. In addition, since the liquid itself is colorless and transparent, even if the scale is immersed in the liquid, it is unknown which part of the scale the liquid level has reached, even if the scale is taken out and no trace remains Because.

[0003]

However, since the indirect measurement method involves a predetermined mediating element, a measurement error is generated accordingly. The present invention has been proposed in view of the above background, and an illuminance difference detection type liquid level meter capable of relatively directly measuring a liquid level in a storage tank which is difficult to directly measure. The purpose is to provide.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a liquid level gauge for measuring a liquid level in a container which is not directly visible, and comprising a plurality of optical fibers fixed to a long member. The optical fiber is configured to be lowered toward the liquid level in the container together with the long member, and the optical fiber transmits the light from the light emitting means and transmits the light from the end side close to the liquid level. And an optical fiber for irradiating light toward the liquid surface, and irregularly reflected light from the liquid surface is received from an end portion close to the liquid surface, and the received irregularly reflected light is transmitted to a light receiver. A plurality of light receiving optical fibers as described above, the positions of the ends of the light receiving optical fibers close to the liquid surface are different from each other, and light is emitted from the ends of the light irradiation optical fibers close to the liquid surface. Irradiate the optical fiber toward the liquid surface in the container When lowering to monitor the intensity difference between the diffuse reflection light received at each light-receiving optical fiber,
By detecting the illuminance difference, it is determined that one of the ends of the optical fiber for light reception close to the liquid surface has reached the liquid surface, and the position of the liquid surface is grasped. In the above-described configuration, a plurality of optical fibers are fixed to a long member with a scale and a plurality of optical fibers are fixed, and the long member is lowered toward the liquid surface in the container together with the optical fibers,
By detecting the illuminance difference of the irregularly reflected light received by each light receiving optical fiber, as one of the ends of the light receiving optical fiber close to the liquid surface reaches the liquid surface,
The position of the liquid level is determined based on the scale of the long member. Further, the irradiation light from the light irradiation optical fiber is captured by the first and second light receiving optical fibers, respectively, and the change in the illuminance of the reflected light captured by the first and second light receiving optical fibers is respectively detected. Monitoring was performed, and when the irradiation end of the light irradiation optical fiber was in contact with the liquid surface, it was recognized as a large variation in illuminance, and the position of the liquid surface was grasped. Further, the present invention is a liquid level gauge for capturing a liquid level in a container that is not directly visible, and has a plurality of optical fibers fixed to a long member, and these optical fibers are used together with the long member to measure a liquid level in the container. And a light irradiation optical fiber configured to transmit light from the light emitting means and irradiate the light toward the liquid surface from an end portion close to the liquid surface. And a plurality of light receiving optical fibers configured to receive the irregularly reflected light from the liquid surface from an end portion close to the liquid surface and to transmit the received irregularly reflected light to a light receiver. The position of the end of the optical fiber close to the liquid surface is set to the same position, and the optical fiber is lowered toward the liquid surface in the container while irradiating light from the end of the optical fiber for light irradiation close to the liquid surface. At the same time, the disturbance received by each receiving optical fiber Monitoring the variations in the illuminance of Shako, irradiation end in the light irradiation optical fiber by detecting the variation as reaches the liquid surface and so as to grasp the position of the liquid surface. In the above-described configuration, a plurality of optical fibers are fixed to a long member with a scale, and the optical fibers are lowered together with the long member toward a liquid surface in a container. By detecting a change in illuminance of the irregularly reflected light received by the light receiving optical fiber, it is determined that the irradiation end of the light irradiating optical fiber has reached the liquid surface, and the position of the liquid surface is determined based on the scale of the long member. I tried to figure out.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an illuminance difference detection type liquid level meter according to the present invention will be described with reference to the attached drawings and an embodiment. FIG. 1 shows an illuminance difference detection type liquid level meter 1 for measuring the liquid level of an ultra-low temperature liquid (for example, liquid nitrogen) stored in a storage tank 2. . That is, the illuminance difference detection type liquid level meter 1 has a plurality of optical fibers 4 for transmitting and receiving light having a light irradiating end and a light incident end on the lower end while a light transmitting / receiving section 3 for measuring light is mounted on the upper end. The optical fiber 4 for transmitting and receiving light is fixed to a long member (described later) provided with a scale. The light transmitting and receiving optical fiber 4 includes a light irradiating optical fiber 4 a configured to allow light from a light emitting device (described later) in the light transmitting and receiving unit 3 to pass through the inside from the upper end and radiate outward from the lower end. A first and a second light receiving device is configured to receive the irregularly reflected light of the light emitted from the light irradiation optical fiber 4a from the lower end and to transmit the light to a light receiver (described later) in the optical transceiver 3 attached to the upper end. Light receiving optical fibers 4b and 4c.

As shown in FIG. 2, the light transmitting / receiving section 3 includes a light emitting device 5 attached to an upper end of a light irradiation optical fiber 4a.
(For example, a light emitting diode 5) and a light receiver 6 (for example, a photocell 6) attached to the upper end side of the first and second light receiving optical fibers 4b, 4c. An illuminometer 7 is connected to the photocells 6 on the upper ends of both the first and second light receiving optical fibers 4b and 4c. The lower ends of the light irradiation optical fiber 4a and the first and second light receiving optical fibers 4b and 4c are penetrated and held by a weight 9 attached to the lower end of a long member 8 (for example, a stainless wire 8). I have. The lower ends of the light irradiation optical fiber 4a and the first and second light receiving optical fibers 4b and 4c are set to have different heights from each other. The light-irradiating optical fiber 4a and the first and second light-receiving optical fibers 4b and 4c are fixed to the stainless steel wire 8 along the stainless steel wire 8, but are separately illustrated in FIG. I have.

With the above configuration, the optical fiber 4a for light irradiation and the first and second stainless steel wires 8 are provided.
The light receiving optical fibers 4b and 4c are inserted into the inside of the storage tank 2 from the communication port 10 provided at the top of the storage tank 2, and are lowered toward the liquid surface to be stored. At this time, the light irradiated from the lower end side of the light irradiation optical fiber 4a is received from the lower end sides of the first and second light receiving optical fibers 4b and 4c as irregularly reflected light from the liquid surface. Is captured by the photocell 6 on the upper end side through the first and second light receiving optical fibers 4b and 4c, and the illuminance difference meter 7 monitors the illuminance difference. In this case, especially the atmosphere very close to the liquid surface,
The liquid may be in an entrained state due to boiling due to the extremely low temperature liquid, and the first and second light receiving optical fibers 4b, 4c
A small illuminance difference may occur between the irregularly reflected lights captured by the photocells 6 on the upper end side through the illuminator. This illuminance difference is larger than the small illuminance difference by the illuminometer 7. By detecting that the light receiving end has reached the liquid level, the light receiving end, which is the lower end side of the first light receiving optical fiber 4b, has reached the liquid level. Is used to calculate the position of the liquid surface. That is, the first and second light receiving optical fibers 4
When the respective light receiving ends are in the atmosphere, the illuminance of the irregularly reflected light received at b and 4c is only perceived as a small illuminance difference, and there is no large change. The first and second light receiving optical fibers 4b , 4c is in contact with the liquid surface, so that the illuminance difference between the irregularly reflected light captured by the photocell 6 at the upper end of each of the first and second light receiving optical fibers 4b, 4c is large. Because it fluctuates.

In the illuminance difference detection type liquid level meter 1 constructed as described above, the stainless steel wire 8 is held by the weight 9 together with the light irradiation optical fiber 4a and the first and second light receiving optical fibers 4b and 4c in the storage tank. 2 is inserted into the storage tank 2 from the communication port 10 at the top, and is lowered toward the liquid level to be stored. The light emitted from the light emitting diode 5 on the upper end side of the light irradiation optical fiber 4a in the light transmitting / receiving unit 3 passes through the light irradiation optical fiber 4a and is irradiated from the lower end toward the liquid surface. The irradiating light passes through the atmosphere of the place and is irregularly reflected on the liquid surface, and from the lower ends of the first and second light receiving optical fibers 4b and 4c, respectively, the first and second light receiving optical fibers 4b and 4c. Photocell 6 on the top side through
Reach At this time, the first and second light receiving optical fibers 4
The illuminance meter 7 can monitor the illuminance difference between the first and second light receiving optical fibers 4b and 4c from the reflected light respectively captured by the photocells 6 on the upper end sides of the b and 4c. That is, when one of the light receiving ends at the lower ends of the first and second light receiving optical fibers 4b and 4c reaches the liquid surface, the illuminance greatly changes. As a result, the light receiving end, which is the lower end side of the first light receiving optical fiber 4b, reaches the liquid level, reads the scale of the stainless steel wire 8 at this time, and refers to the drawing of the storage tank 2 for the liquid level. Can be calculated.

Further, the illuminance difference detection type liquid level meter 1 according to the present invention separately captures the irradiation light from the light irradiation optical fiber 4a by the first and second light receiving optical fibers 4b and 4c, respectively. Changes in the illuminance of the reflected light may be monitored.
In this case, an illuminometer can be connected to each of the photocells 6 on the upper ends of the first and second light receiving optical fibers 4b and 4c. By doing so, the light irradiation optical fiber 4
When the light irradiation end of a is in contact with the liquid surface, it can be grasped as a large change in illuminance, and the position of the liquid surface at that time can be calculated. By taking the average of the values, the accuracy of the illuminometer 7 is suppressed, even if the liquid level is in a state of entrainment due to evaporation, and errors are suppressed even if there is a change in the zero point. Thus, the position of the liquid surface can be more accurately grasped.

Further, in the illuminance difference detection type liquid level meter 1 according to the present invention, the lower ends of the first and second light receiving optical fibers 4b and 4c can be set at substantially the same height. In this case, the irregularly reflected light of the light emitted from the light irradiation optical fiber 4a is received by the first and second light receiving optical fibers 4b and 4c, respectively, and the fluctuation of the illuminance of the received irregularly reflected light is monitored. Then, by detecting the change in the illuminance, it is possible to determine the position of the liquid surface assuming that the lower end side of the optical fiber for light irradiation 4a has reached the liquid surface. If an average value is obtained even if both of the obtained values vary, the accuracy of the illuminance meter 7, mainly errors due to the fluctuation of the zero point, can be suppressed, and a more accurate liquid The position of the surface can be grasped.

[0011]

According to the present invention, the liquid level in the storage tank, which is difficult to measure directly, can be measured relatively easily, and highly accurate measurement can be performed.

[0011]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an entire ultralow temperature storage tank provided with an illuminance difference detection type liquid level meter according to the present invention.

FIG. 2 is a schematic structural explanatory view showing an example of an illuminance difference detection type liquid level meter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination difference detection type liquid level meter 2 Storage tank 3 Optical transmission / reception part 4 Optical fiber for transmission / reception 4a Optical fiber for light irradiation 4b First optical fiber for light reception 4c Second optical fiber for light reception 5 Light emitting diode 6 Photocell 7 Illuminance meter 8 Stainless wire 9 Weight 10 Communication port

Claims (5)

[Claims] 1. A liquid level gauge for capturing a liquid level in a container which is not directly visible, comprising a plurality of optical fibers fixed to a long member, and the optical fibers together with the long member being a liquid level in the container. And the optical fiber,
A light irradiating optical fiber configured to transmit light from the light emitting means and irradiate the light toward the liquid surface from an end portion close to the liquid surface, and diffusely reflected light from the liquid surface close to the liquid surface. Having a plurality of optical fibers for light reception, which are adapted to transmit the received irregularly reflected light to the light receiver,
The positions of the end portions of the optical fibers for light reception close to the liquid surface are different from each other, and the optical fibers are directed toward the liquid surface in the container while irradiating light from the ends of the optical fibers for light irradiation close to the liquid surface. When descending, the illuminance difference of the irregularly-reflected light received by each light-receiving optical fiber is monitored, and by detecting this illuminance difference, any one of the ends of the light-receiving optical fiber close to the liquid surface is detected. An illuminance difference detection type liquid level meter characterized in that the position of the liquid level is grasped assuming that the object has reached the liquid level. 2. A structure in which a plurality of optical fibers are fixed to an elongated member on which the plurality of optical fibers are graduated, and the elongated member is lowered together with the optical fibers toward a liquid level in a container. By detecting the illuminance difference of the irregularly-reflected light received by the light-receiving optical fiber, one of the ends of the light-receiving optical fiber close to the liquid surface reaches the liquid surface. The illuminance difference detection type liquid level meter according to claim 1, wherein the position of the liquid level is grasped based on a scale. 3. Irradiation light from the light irradiation optical fiber is captured by first and second light receiving optical fibers, respectively, and the illuminance of reflected light captured by the first and second light receiving optical fibers is measured. The fluctuations are monitored individually, and the irradiation end of the optical fiber for light irradiation comes into contact with the liquid surface, so that each of them is regarded as a large fluctuation of the illuminance, and the position of the liquid surface is grasped. The illuminance difference detection type liquid level meter according to 1 or 2. 4. A liquid level meter for catching a liquid level in a container which is not directly visible, comprising a plurality of optical fibers fixed to a long member, and the optical fibers together with the long member being a liquid level in the container. And the optical fiber,
A light irradiating optical fiber configured to transmit light from the light emitting means and irradiate the light toward the liquid surface from an end portion close to the liquid surface, and diffusely reflected light from the liquid surface close to the liquid surface. Having a plurality of optical fibers for light reception, which are adapted to transmit the received irregularly reflected light to the light receiver,
The positions of the ends of the optical fibers for light reception close to the liquid surface are set to the same position, and the optical fibers are directed toward the liquid surface in the container while irradiating light from the ends of the optical fibers for light irradiation close to the liquid surface. When descending, monitoring the fluctuation of the illuminance of the irregularly reflected light received by each light receiving optical fiber, and assuming that the irradiation end of the light irradiation optical fiber reaches the liquid surface by detecting this fluctuation, An illuminance difference detection type liquid level meter characterized by grasping a liquid level position. 5. A structure in which a plurality of optical fibers are fixed to an elongated member on which the plurality of optical fibers are graduated, and the optical fiber is lowered toward a liquid level in a container together with the elongated member, By detecting a change in the illuminance of the irregularly reflected light received by the light receiving optical fiber, the irradiation end of the light irradiating optical fiber reaches the liquid level, and the liquid level of the liquid surface is determined based on the scale of the long member. The illuminance difference detection type liquid level meter according to claim 4, wherein the position is grasped.