JPH1130547A - Photoelectric liquid level-detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to detect a liquid level without being influenced by outside temperature, liquid temperature and humidity, and make it possible to continuously detect a correct liquid level by preventing adhesion of dust surely. SOLUTION: A light-emitting element 12 and a photodetecting element 13 are arranged with the same angle of incidence and the same angle of refraction to an outer surface of a transparent pipe 11 to detect a liquid face. The light- emitting element 12 and the photodetecting element 13 are set at positions with angles so that when a liquid is either present or absent in the transparent pipe 11, the light emitted from the light-emitting element 12 passes the transparent pipe 11 to enter an internal space of the transparent pipe 11, passes a liquid layer or gas layer of the transparent pipe 11, and again passes the transparent pipe 11 to be detected by the photodetecting element 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric liquid level detecting device for detecting a liquid level of a liquid stored in a liquid storage tank or the like.

[0002]

2. Description of the Related Art Conventionally, various photoelectric liquid level detecting devices for detecting the liquid level of a liquid stored in a liquid storage tank and the liquid level of a liquid filled in a bottle or the like have been proposed.

[0003] For example, the photoelectric liquid level detector disclosed in Japanese Utility Model Laid-Open No. 55-112223 (hereinafter referred to as the prior art 1).
Is an auxiliary device comprising a light emitting device having a light emitting element and a light emitting lens, a light receiving device having a light receiving element and a light receiving lens, and a transparent member provided externally to a tank for storing liquid. A water channel, a slit for limiting light emitted from the light emitting element via the light projecting lens, and a shielding plate for limiting light received by the light receiving device via the light receiving lens; The configuration is such that, at a predetermined height position of the auxiliary channel, it is arranged at a symmetrical position on the left and right through the auxiliary channel.

[0004] Further, an apparatus for inspecting the liquid level in a container disclosed in Japanese Utility Model Publication No. 37-5174 (hereinafter referred to as "prior art 2") has light receiving devices on both sides in the moving direction of the optically transparent container to be moved. And two sets of photometric devices comprising a light source and a light source comprising a lens, and two sets of photometric devices arranged vertically so that the parallel luminous flux emitted from each of the two light emitting devices is above and below a predetermined liquid level position of the container. In addition, a light shielding plate is arranged between the light emitting device and the container and between the light receiving device and the container.

Further, a liquid level detecting device disclosed in Japanese Utility Model Laid-Open Publication No. 7-14327 (hereinafter referred to as prior art 3) has a light-transmitting container such as a beer bottle for storing a liquid, From the outside of the container to the liquid level of the liquid in the container, from below the liquid surface, a projector that projects light at an angle larger than the critical angle, and centering on the container,
An optical detector comprising a plurality of photoelectric receivers arranged in the level direction of the liquid at a position opposite to the light emitter, and a signal processing circuit for processing an output signal of the optical detector are provided. It has a configuration.

[0006]

However, since the prior arts 1 and 2 both use a lens, dust or dirt adheres to the surface of the lens, fogging occurs, and the outside air temperature is low and the liquid temperature is high. In some cases, such as when the humidity is high, there is a problem that dew condensation occurs on the lens surface and detection becomes difficult.

Further, the prior arts 1 and 2 require a shielding plate (light shielding plate) for shielding the light emitted from the light emitting element or the light emitting device, so that the number of parts is increased and the space is small. There was also a problem that hindered the development.

Further, in the case of the prior art 1, dust and dirt stick to the surfaces of the auxiliary water channel (transparent member), the predetermined height level portion, the light transmitting element, the light transmitting lens, the light receiving element, the light receiving lens and the like. In order to prevent the detection from becoming difficult, these are entirely covered with a cover member, but there is a problem that the cover member becomes large and bulky.

In the prior art 1, the light emitting element,
The mutual positional relationship between the light projecting lens, the auxiliary water channel (transparent member), the light receiving element, the light receiving lens, and the shielding plate. In the case of the prior art 2, the relative positions of the light source, the lens, the two light shielding plates, and the light receiving device. There is a problem that the relationship is extremely delicate and it is very difficult to set an appropriate positional relationship.

The prior art 3 has a light transmitting property.
From inside the container such as a beer bottle
Project light at an angle greater than the critical angle
It is said that. However, the stage of the first embodiment of the prior art 3
In the drop 11, “the incident angle becomes larger than θc
Then, the refracted light no longer exists and all become reflected light. this
The incident angle θc at the boundary is called a critical angle. Detect liquid level
Light from this critical angle and detect it with the photodetector 4
do it. It is described. In addition, generally well
As is known, right-angle prisms are perpendicular to each side.
It has the characteristic of totally reflecting the emitted light at right angles on other surfaces.
It is used for various optical machines. Such a light
Because of its properties, to detect the liquid level,
Light is projected from just the critical angle, and refracted light
Advance along the liquid surface and make sure that the photodetector 4 detects it.
I have to. That is, the structure shown in the prior art 3 is used.
If you choose to use beer bottles,
Project light at the critical angle (just the critical angle)
The refracted light that has escaped into the atmosphere
Must be detected by a photodetector.
No. However, the incident angle θ larger than the critical angle₁Project light at
The light does not travel along the water surface and the incident angle θ ₁When
Reflection angle θ that is the same angle₁Is totally reflected by
It will not be detected by the emitter. Also, beer
There is a subtle bulge at the mouth of a container such as
It becomes even more difficult. Also, beer bottles, etc.
Bubbles on the surface of the liquid contained in the container
Then, light is irregularly reflected, making it difficult to travel along the liquid surface,
It is extremely difficult to detect with a photodetector.
You. Furthermore, liquids in narrow-mouthed containers such as beer bottles
Surface rises or dents due to surface tension
(Refer to FIGS. 5 and 6 of Prior Art 3).
Light) and is not level, light is critical
The light is projected at an angle and the refracted light emitted into the atmosphere travels along the liquid surface.
And it is extremely difficult to detect
Become.

The present invention has been made in order to solve such a problem, and an object of the present invention is to detect a liquid surface without being affected by an outside air temperature, a liquid temperature, and a humidity, and to detect dust and dirt. It is an object of the present invention to provide a photoelectric liquid level detecting device which can surely prevent the adhesion of the liquid crystal, does not increase the number of parts, can reduce the space, and can easily set the positional relationship between the light emitting element and the light receiving element.

[0012]

In order to solve the above-mentioned problems, a photoelectric liquid level detecting device according to a first aspect of the present invention comprises: a liquid storage section having a light transmitting member for detecting a liquid level; A light-emitting element and a light-receiving element disposed at the same angle of incidence and refraction with respect to the outer surface of the light-transmitting member, respectively, and either one of a state in which liquid is present in the liquid storage part and a state in which no liquid is present therein Only the light emitted from the light emitting element is refracted by the outer surface of the light transmitting member and enters the internal space of the liquid storage portion, and the inner surface of the light transmitting member and the liquid layer or the gas layer in the internal space. The light-emitting element and the light-receiving element are refracted at the boundary surface with the light-transmitting member, enter the light-transmitting member again, are refracted, are further refracted on the outer surface of the light-transmitting member, and are received by the light receiving element. The position and angle of arrangement with the element Are those constant.

According to a second aspect of the present invention, there is provided a photoelectric liquid level detecting device, wherein a liquid storing portion having a light transmitting member for detecting a liquid level and an outer surface of the light transmitting member are the same. A light-emitting element and a light-receiving element arranged while maintaining the incident angle and the refraction angle of light, and an optical path between the light-emitting element and the outer surface of the light-transmitting member and between the light-receiving element and the outer surface of the light-transmitting member. And a protection member for protecting each of the optical paths in a sealed state, and only in one of a state where liquid is present in the liquid storage part and a state where no liquid is present, light emitted from the light emitting element emits light in the liquid storage part. The light-receiving element enters the internal space of the liquid storage portion through the light transmitting member, passes through the liquid layer or the gas layer in the internal space of the liquid storage portion, passes through the light transmitting member again, and is outside the light transmitting member. Said luminescent element as received by Are those set position and arrangement angle of the light receiving element and.

According to a third aspect of the present invention, there is provided the photoelectric liquid level detecting device according to the first or second aspect, wherein the incident angle of the light emitting element is set within a range of 10 ° to 60 °. Is what it is.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of a liquid storage tank 1 to which a photoelectric liquid level detecting device according to the present invention is applied.

The liquid storage tank 1 is provided with clean water, medium water, fire fighting water,
This is a storage tank for storing various liquids such as highly corrosive liquids, and is installed in hospitals, schools, high-rise houses, apartment houses, factories, and the like.

A liquid storage tank (high water tank) 1 shown here is connected to a water receiving tank (not shown) via a water pump 3 provided with a water pump 2, and an overflow pipe is provided above the liquid tank 1. 4 is attached.

A photoelectric liquid level detecting device 10 according to the present invention is mounted on an outer wall 1a of the liquid storage tank 1.

This photoelectric type liquid level detecting device 10 comprises a liquid storage tank 1
A transparent tube (liquid storage portion) 11 which is externally attached to the outer wall 1a and which is erected, and a light emitting element which is arranged with the same incident angle and refraction angle with respect to the outer surface of the transparent tube 11 respectively. 12 and the light receiving element 13 and the light emitting element 12
A fiber unit (shown by a broken line) 14 for connecting the light receiving element 13 and an amplifier unit 15 connected to the fiber unit 14 for transmitting and receiving signals to and from a control panel 25 are provided. As a material of the transparent tube 11, a synthetic resin such as plastic or a glass material is suitably used.

In the present embodiment, the light-emitting element 12 and the light-receiving element 13 are provided for detecting each level of the liquid stored in the liquid storage tank 1 (ie, the upper alarm level H ', the high level H, the low level L, and the lower alarm level). L ′: this level will be described later), and the fiber unit 14 and the amplifier unit 15 are also arranged correspondingly.

The upper end of the transparent tube 11 is connected via an upper gauge valve 16 to a communication hole 1b formed in the outer wall 1a above the upper alarm level H '. It is connected via a gauge valve 17 to a communication hole 1c formed in the outer wall 1a below the lower limit alarm level L '.

That is, a flange 18 having a plurality of (at least two or more) female screw holes for screwing a bolt 19 is formed around the outer surface of the communication hole 1b of the outer wall 1a.
The flange 18 is fixed in a watertight manner by welding or bonding.
Is provided with a flange 16a of the upper gauge valve 16 via a waterproof material (not shown) (not shown).
9 is screwed into each of the female screw holes of the flange 18 from the side of the flange 16a, so that the flange 16 is
a, and the upper gauge valve 16 is attached to the outer wall 1a. Similarly, the flange 18 fixed around the outer surface of the communication hole 1c below the outer wall 1a has
The flange portion 17a of the lower gauge valve 17 is attached. The present invention is not limited to the flange connection as described above, and may be fixed to the liquid storage tank 1 by direct welding or the like. The upper end of the transparent tube 11 does not necessarily need to be in communication with the liquid storage tank 1, and the lower end of the transparent tube 11 may be in communication with the liquid storage tank 1.

A discharge pipe 21 having an open / close valve 22 is attached to a lower port of the lower gauge valve 17. That is, by opening the open / close valve 22 after closing the lower gauge valve 17, the liquid in the transparent tube 11 can be discharged to the outside through the open / close valve 22 and the discharge tube 21.

Further, the open / close valve 22 is closed,
When the gauge valves 16 and 17 are opened, the liquid in the liquid storage tank 1 flows into the transparent tube 11, and at this time, the liquid level of the liquid in the liquid storage tank 1 and the liquid The surface is at the same liquid level. That is, the liquid level of the transparent tube 11 indicates the liquid level in the liquid storage tank 1.

Each of the photoelectric liquid level detecting devices 10, 10,.
When the liquid level in the transparent tube 11 is detected by..., A signal from each liquid level detecting device 10, 10,... Is supplied to the control panel 25 to control the energization of the pump 2 at the same time. Lighting / extinguishing of the alarm lamp 26 and sounding / stopping of the alarm buzzer 27 are controlled.

That is, the liquid level of the liquid stored in the liquid storage tank (high water tank) 1 usually fluctuates within a set range. For example, the liquid storage tank 1
When the liquid level in the tank falls to a low level L, the photoelectric liquid level detecting device 10 arranged at the level L detects the liquid level and activates the pump 2 to pump the liquid in the water receiving tank to the pump pipe 3.
Is supplied into the liquid storage tank 1 via the When the liquid level in the liquid storage tank 1 rises and reaches the high level H, the photoelectric liquid level detecting device 10 arranged at the level H detects the liquid level and stops the operation of the water pump 2. Let it. When an abnormal state occurs and the liquid level drops to level L 'or when the liquid level rises to level H', the alarm lamp 26 is turned on and the alarm buzzer 27 is sounded. I have.

The upper end of the transparent tube 11 is
b is attached to the upper gauge valve 16 by loosening the nut 16b.
The upper end of the transparent tube 11 can be removed from the upper gauge valve 16. Similarly, the lower end of the transparent tube 11 is attached to the lower gauge valve 17 by a nut 17b. By loosening the nut 17b, the lower end of the transparent tube 11 is
7 can be removed. Therefore, the transparent tube 1
When cleaning the inside of the tube 1 or replacing the tube with a new transparent tube 11, the liquid in the transparent tube 11 may be drained, and the nuts 16b and 17b may be loosened and the transparent tube 11 may be removed.

FIGS. 2A and 2B show an embodiment of the arrangement of the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10. FIG. However, in the present embodiment, the transparent tube 11 has a cylindrical shape.

In this embodiment, the light emitting element 12 and the light receiving element 13 are arranged in the same horizontal plane (the state shown in FIG. 1), and the light emitting element 12 is incident on the outer surface of the transparent tube 11 at an incident angle (ie, , The angle with respect to the normal T in the same horizontal plane, θ1 is 90 ° or less (that is, the angle at which the light enters the transparent tube 11 at a critical angle, specifically, in the range of 10 ° to 60 °, more preferably). (In the range of 20 ° to 50 °). The light receiving angle (refractive angle) θ2 of the light receiving element 13 is set to be equal to the incident angle θ1 of the light emitting element 12.

More specifically, in the present embodiment, in a state where there is no liquid in the transparent tube 11, the light emitted from the light emitting element 12 is refracted by the outer surface of the transparent tube 11 and enters the internal space of the transparent tube 11. After being incident and refracted at the boundary between the inner surface of the transparent tube 11 and the gas layer (air layer) in the internal space, it is refracted again at the inner surface of the transparent tube 11,
The arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set so that the light is refracted by the outer surface of the light receiving element 1 and received by the light receiving element 13 (see FIG. 2A).

In practice, when the transparent tube 11 has no liquid, light is emitted from the light emitting element 12 and the light receiving element 1
By determining the position where the light receiving element 3 receives light, the light emitting element 12
The arrangement position and the arrangement angle of the sensor and the light receiving element 13 can be set very easily.

On the other hand, FIG. 2B shows a light path when a liquid is present in the transparent tube 11. That is, the light emitted from the light emitting element 12 is refracted on the outer surface of the transparent tube 11 and is incident on the inner space of the transparent tube 11, and is refracted on the boundary surface between the inner surface of the transparent tube 11 and the liquid layer in the inner space. After that,
The light is refracted on the inner surface of the transparent tube 11 again, and further refracted on the outer surface of the transparent tube 11 and irradiated to the outside. At this time, since the refraction angle r in the liquid layer is smaller than the refraction angle R (= θ1) in the gas layer, the light radiated to the outside from the outer surface of the transparent tube 11 Will pass through.

That is, when there is no liquid in the transparent tube 11, irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is liquid in the transparent tube 11, the light emitting element 12
Are not received by the light receiving element 13.

The light path from the light emitting element 12 to the outer surface of the transparent tube 11 and the light receiving element 1 from the outer surface of the transparent tube 11
The optical paths up to 3 are kept sealed by a protective member 29. As the protection member 29, for example, an elastic material such as a rubber tube or a plastic tube, a cover made of metal or plastic, a putty, or the like is used alone or in combination. That is, the light emitting element 12 and the light receiving element 13 are fixed in the vicinity of the transparent tube 11, and the transparent tube 11 and the light emitting element 12, and the transparent tube 11 and the light receiving element 13 Are connected. That is, with this configuration, dust and dirt do not adhere to the outer surface of the transparent tube 11 protected by the protection member 29, the irradiating portion on the end face of the light emitting element 12, the light receiving section on the end face of the light receiving element 13, and the like. There is no need to worry about poor transmission of light. In addition, if the atmosphere is kept completely closed so that moisture in the atmosphere does not enter the protective member, the light on the outer surface of the transparent tube 11 can be reduced even under bad conditions such as high outside air temperature, cold liquid temperature and high humidity. There is no risk of dew condensation on the passage.

The light emitting element 12 and the light receiving element 13 are
Opposing arrangement on the normal line T (that is, the transparent tube 11 extending vertically
Are not disposed in the same horizontal plane perpendicular to the center axis of the radiator for the following reason. In the case where the light emitting element 12 and the light receiving element 13 are disposed at positions facing each other on the normal line T of the transparent tube 11, if the light flowing through the transparent tube 11 is a granular material, the irradiation light from the light emitting element 12 is , It is possible to detect the granular material. However, if a transparent or translucent liquid flows in the transparent tube 11, the irradiation light from the light emitting element 12 passes through the liquid without being blocked or refracted and is received by the light receiving element 13. That is, regardless of the presence or absence of the liquid, the light emitted from the light emitting element 12 travels straight along the normal line T and is received by the light receiving element 13.
That is, the presence or absence of the liquid cannot be detected.

FIGS. 3A and 3B show another embodiment of the arrangement of the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10. FIG. That is, the light receiving element 13 is disposed on the light path when the liquid is present in the transparent tube 11. The arrangement positions shown in FIGS. 2A and 2B are for detecting light with the light receiving element 13 when there is no liquid in the transparent tube 11, but in this example, there is a liquid in the transparent tube 11. In this case, light is detected by the light receiving element 13. Other configurations are the same as those shown in FIGS. 2 (a) and 2 (b).

That is, in the present embodiment, as shown in FIG. 3B, when there is a liquid in the transparent tube 11,
The light emitted from the light emitting element 12 is refracted by the outer surface of the transparent tube 11 and is incident on the internal space of the transparent tube 11, and the transparent tube 1
After being refracted at the boundary surface between the inner surface of the inner tube 1 and the liquid layer in the internal space, the light is refracted again by the inner surface of the transparent tube 11, further refracted by the outer surface of the transparent tube 11, and received by the light receiving element 13. Thus, the arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set.

In practice, when the liquid is present in the transparent tube 11, light is emitted from the light emitting element 12 and the light receiving element 1
By determining the position where the light receiving element 3 receives light, the light emitting element 12
The arrangement position and the arrangement angle of the sensor and the light receiving element 13 can be set very easily. On the other hand, FIG. 3A shows a light path when there is no liquid in the transparent tube 11. That is, the light emitted from the light emitting element 12 enters the internal space (gas layer) of the transparent tube 11 via the transparent tube 11, enters the transparent tube 11 again, and is emitted from the outer surface of the transparent tube 11 to the outside. You. At this time, since the refraction angle R in the gas layer is larger than the refraction angle r in the liquid layer, light emitted from the outer surface of the transparent tube 11 to the outside passes through a position distant from the light receiving element 13.
That is, when there is a liquid in the transparent tube 11, irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is no liquid in the transparent tube 11, irradiation light from the light emitting element 12 is received. The arrangement is such that the element 13 does not receive light.

FIGS. 4A and 4B show another embodiment of the arrangement of the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10 (the mounting structure to the transparent tube 11). .

That is, the light emitting element 12 and the light receiving element 13
Are exactly the same as those shown in FIGS. 2A and 2B, but in the present embodiment, the light emitting element 1
2 and a tip portion of the light receiving element 13 are formed in a curved surface along the outer surface of the transparent tube 11, and are directly attached to the outer surface of the transparent tube 11, and a fixing member (protective member) such as putty is provided around the periphery. 30
Is attached directly to the transparent tube 11. This prevents dust and dirt from adhering to the outer surface (light path surface) of the transparent tube 11 as in the case of FIGS. 2A and 2B in which the light path is sealed by the protection member 29. can do. Further, it is possible to reliably prevent the moisture in the atmosphere from entering the protective member 29 and condensing on the outer surface of the transparent tube 11. Further, the light emitting element 12 and the light receiving element 13
Can be firmly fixed while being in contact with the outer surface of the transparent tube 11, so that the path of light can be more accurately secured.

In the case of a normal liquid storage tank, three to five electrode rods are hung from the ceiling, or a float that can swing up and down is floated on the liquid surface to detect the liquid surface. However, when the liquid in the liquid storage tank has a strong corrosive property, such a liquid level detecting device for directly contacting the liquid level detector with the liquid may not be adopted. However, in the case of the present invention, since it is not necessary to bring the photoelectric liquid level detecting device 10 into direct contact with the liquid, the liquid storage tank 1 and a liquid storage section for detecting the liquid level (a storage section around the transparent tube 11). Is made of a material such as plastic having strong corrosion resistance, it is possible to accurately detect the liquid level over time over a long period of time.

The light emitting element 12 is provided on the outer surface of the transparent tube 11.
In addition, since the light receiving element 13 is simply provided, the cost is low.

FIGS. 5A and 5B show another embodiment of a mounting structure for mounting the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10 to the transparent tube 11. FIG.

In this embodiment, the light emitting element 12 and the light receiving element 13 are not directly attached to the transparent tube 11, but are attached to a protection tube 31 for protecting the transparent tube 11.

The protection tube 31 is formed in a substantially cylindrical shape, and the transparent tube 11 is inserted into the cylindrical protection tube 31. The side surface of the protective tube 31 is provided with a notch 32 cut in a slit shape from the vicinity of the upper edge to the vicinity of the lower edge thereof, so that the inside of the transparent tube 11 can be visually observed. ing.

On the peripheral surface opposite to the notch 32, the light emitting side optical path tube 3 for screwing and fixing the light emitting element 12 to form an optical path is formed.
3 and a light receiving side light path tube 34 for screwing and fixing the light receiving element 13 to form an optical path. The light-emitting-side light path tube 33 and the light-receiving-side light path tube 34 also serve as the protective member according to the third aspect. The light-emitting side light path tube 33 and the light-receiving side light path tube 34 are arranged in the same horizontal plane, and
Means that the incident angle θ1 with respect to the outer surface of the transparent tube 11 is 90 °
Below (that is, below the angle of incidence at the critical angle on the transparent tube 11; specifically, within the range of 10 ° to 60 °, more preferably within the range of 20 ° to 50 °). I have. Further, the light receiving angle (refraction angle) θ2 of the light receiving side optical path tube 34
Is set to be equal to the incident angle θ1 of the light-emitting side optical path tube 33.

On the inner peripheral surfaces of the light-emitting side optical path tube 33 and the light-receiving side optical path tube 34, female screw portions 33a and 34a are formed, respectively. On the other hand, the light emitting element 12 and the light receiving element 13 have external thread portions 35a and 36a formed on the outer peripheral surface,
It is held in such a manner that it is housed in holding members 35, 36 formed with stopper flange portions 35b, 36b, respectively. Then, the male screw portion 35a of the holding member 35 holding and holding the light emitting element 12 is screwed into the female screw portion 33a of the light emitting side optical path tube 33 until the flange portion 35b contacts, thereby fixing the light emitting element 12 at a predetermined incident angle θ1. And
Male screw 3 of holding member 36 holding and holding light receiving element 13
The light receiving element 13 is fixed to a predetermined light receiving angle (refraction angle) θ2 by screwing the light receiving element 6a into the female screw part 34a of the light receiving side optical path tube 34 until the flange part 36b abuts.

That is, by simply screwing the holding member 35 containing the light emitting element 12 into the light emitting side optical path tube 33, the light emitting element 12
2 and FIG. 4 can be set by simply screwing the holding member 36 accommodating the light receiving element 13 into the light receiving side optical path tube 34. The positional relationship between the light emitting element 12 and the light receiving element 13 can be set very easily as compared with the mounting structure described above. Therefore, maintenance and inspection, replacement work, and the like of the light emitting element 12 and the light receiving element 13 can be easily performed.

It is to be noted that the light-emitting element 1
2 and the light receiving element 13, when the male screw portions 35 a and 36 a are screwed into the female screw portions 33 a and 34 a of the light emitting side light path tube 33 and the light receiving side light path tube 34, respectively. Are holding members 35 and 3
6 (ie, the fiber unit 1
(4 is twisted) does not occur.

In FIG. 5B, one protection tube 31 is provided.
Although two sets of upper and lower light-emitting side optical path tubes 33 and light-receiving side optical path tubes 34 are provided, one or a plurality of sets can be provided in one protective tube 31 as necessary.

FIGS. 6A and 6B show another embodiment of the mounting structure for mounting the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10 to the transparent tube 11.

In this embodiment, the light emitting element 12 and the light receiving element 13 are not directly attached to the transparent tube 11, but are attached to a support member 41 attached to the outer wall 1a of the liquid storage tank 1.

The support member 41 has a flange 43 attached to the outer wall 1a of the liquid storage tank 1 on one side of a flat support body 42 by welding or bonding.
It is formed in the shape of a letter.
A pair of arm pieces 4 extending parallel to the transparent tube 11 side
4, 45 are formed. These arm pieces 44 and 45
A light-emitting side light path tube 46 for screwing and fixing the light emitting element 12 to form an optical path, and a light receiving side light path tube 47 for screwing and fixing the light receiving element 13 to form an optical path are provided.

The light-emitting side optical path tube 46 and the light-receiving side optical path tube 47 are arranged in the same horizontal plane, and
Means that the incident angle θ1 with respect to the outer surface of the transparent tube 11 is 90 °
Below (that is, below the angle of incidence at the critical angle on the transparent tube 11; specifically, within the range of 10 ° to 60 °, more preferably within the range of 20 ° to 50 °). I have. Also, the light receiving angle (refraction angle) θ of the light receiving side optical path tube 47
2 is set to be equal to the incident angle θ1 of the light-emitting side optical path tube 46.

On the inner peripheral surfaces of the light-emitting side optical path tube 46 and the light-receiving side optical path tube 47, female screw portions 46a, 47a are formed, respectively. On the other hand, the light emitting element 12 and the light receiving element 13 have external thread portions 48a, 49a formed on the outer peripheral surface thereof,
It is held in such a manner that it is housed in holding members 48, 49 having hitting flange portions 48b, 49b formed thereon, respectively. The light emitting element 12 is fixed at a predetermined incident angle θ1 by screwing the male screw part 48a of the holding member 48 housing and holding the light emitting element 12 into the female screw part 46a of the light emitting side optical path tube 46 until the flange part 48b abuts. And
Male screw 4 of holding member 49 holding and holding light receiving element 13
The light receiving element 13 is fixed to a predetermined light receiving angle (refraction angle) θ2 by screwing the light receiving element 9a into the female screw portion 47a of the light receiving side optical path tube 47 until the flange portion 49b abuts.

That is, by simply screwing the holding member 48 containing the light emitting element 12 into the light emitting side optical path tube 46, the light emitting element 12
2 can be set by simply screwing the holding member 49 accommodating the light-receiving element 13 into the light-receiving side optical path tube 47, so that the position and angle of the light-receiving element 13 can be set. The positional relationship between the light emitting element 12 and the light receiving element 13 can be set very easily as compared with the mounting structure described above.

In this embodiment, the light-emitting side optical path tube 46 is used.
The optical path from the outer surface of the transparent tube 11 to the outer surface of the transparent tube 11 and the optical path from the outer surface of the transparent tube 11 to the light receiving side optical path tube 47 are hermetically protected by a protective member 50 made of, for example, a rubber tube, a plastic tube, a metal tube, or the like. ing. That is, the light emitting side light path tube 46 or the light receiving side light path tube 47 is coupled and fixed to one opening of the protective member 50, and the other opening is formed on a curved surface along the outer surface of the transparent tube 11.
1 is in contact with the outer surface. At this time, if necessary,
A band, an adhesive, a putty and the like are used in combination. Therefore, no dust, dust, or the like adheres to the outer surface of the transparent tube 11 protected by the protection member 50, and there is no fear that light transmission deteriorates.

Note that the holding members 48 and 49 are
2 and the light receiving element 13 so as to be rotatable, the male screw portion is connected to the light emitting side light path tube 46 and the light receiving side light path tube 47.
When the screw is screwed into the female screw portion, the problem that the light emitting element 12 and the light receiving element 13 rotate with the holding members 48 and 49 (that is, the fiber unit 14 is twisted) does not occur.

FIGS. 7A and 7B show another embodiment of the photoelectric liquid level detecting device 10 of the present invention.

In the present embodiment, the liquid storage portion provided externally to the outer wall 1a of the liquid storage tank 1 has the same structure as the conventional transparent liquid level meter, instead of the cylindrical transparent tube 11. It was done.

That is, two vertically long transparent glass plates 5
1 and 52 are opposed to each other, and packings 55 and 55 for stopping water are positioned on the entire peripheral edge of both facing surfaces. The opposite surfaces of the transparent glass plates 51, 52 are fitted into the recesses 53a, 53a on both sides of the vertically long space (slit) 56 of the spacer member 53, respectively, so that these transparent glass plates 51, 52 are fitted. The glass plates 51, 52, the spacer member 53, and the packing 55, 55 for stopping water form a space 56 for raising and lowering the liquid. In addition, the transparent glass plate 5
Cushion members 57, 57 are located on the entire peripheral edge of the outer surface (opposite to the space 56) of the first and second 52, respectively, and vertically long through holes (transparent windows) 58c, 59 of the holding plates 58, 59 are provided.
c, respectively, are fitted in the recesses 58a, 59a inside, and the outer sides of these holding plates 58, 59 are tightened with stud bolts 60 and nuts 61, 61, so that the holding plates 58, 59 are transparent. Glass plates 51, 52
And the spacer member 53 is integrally fixed.

Note that bolt insertion holes 58b, 59b are formed all around the side edges of the holding plates 58, 59, and a spacer member 53 facing the bolt insertion holes 58b, 59b.
A bolt insertion hole 53b is also formed on the entire periphery of the side edge portion. Here, the stud bolt 60 having the male screw portions 60a, 60a formed at both ends is inserted into the bolt insertion holes 58b,
53b, 59b, and the male screw portions 60a, 60a, 60b at both ends of the stud bolt 60 protruding from the holding plates 58, 59.
The nuts 61, 61 are screwed into the 60a, respectively, and tightened so that the holding plates 58, 59, the transparent glass plate 5
1, 52 and the spacer member 53 are integrally fixed.

The stud bolt 60 and the nuts 61, 61
As shown in FIG. 7A, a plurality of sets of fasteners are attached to the entire periphery of the side edges of the holding plates 58 and 59 at predetermined intervals. However, instead of the stud bolts (headless bolts provided with screws at both ends) 60, long bolts (headed bolts) may be used. In addition, vertically long transparent windows 58c, 59c are formed in the holding plates 58, 59, and the liquid in the space 56 is filled with the transparent glass plates 51, 59.
It can be seen through 52.

In the liquid storage section (perspective liquid level meter) having such a structure, in the present embodiment, the light emitting element 12 is arranged outside one transparent glass plate 51 and the light receiving element 13 is connected to the other transparent glass plate. 52 is arranged outside. That is,
A light-emitting side light path tube 6 for fixing the light-emitting element 12 to the outside of one transparent glass plate 51 with a set screw 54 to form an optical path.
2 and a light-receiving-side optical path tube 63 that forms an optical path by fixing the light-receiving element 13 with a set screw 54 is disposed outside the other transparent glass plate 52.

The light-emitting side optical path tube 62 is attached to a support plate 62a, and the support plate 62a is
8 and is fixed using stud bolts 60 and nuts 61. The light receiving side optical path tube 63 is provided on a support plate 63a, and the support plate 63a is attached to the outer surface of the holding plate 59,
It is fixed using a stud bolt 60 and a nut 61.

The light-emitting-side light path tube 62 and the light-receiving-side light path tube 63 are arranged on the same horizontal plane.
Is that the incident angle θ1 with respect to the outer surface of the transparent glass plate 51 is 90 ° or less (that is, the angle at which the light enters the transparent glass plate 51 at a critical angle; specifically, in the range of 10 ° to 60 °, more preferably Is in the range of 20 ° to 50 °). The light receiving angle (refraction angle) θ2 of the light receiving side optical path tube 63 is the incident angle θ1 of the light emitting side optical path tube 62.
The angle is set to be equal to.

More specifically, in the present embodiment, in a state where the liquid exists in the space 56, the light emitted from the light emitting element 12 is refracted by the outer surface of the transparent glass plate 51 and enters the space 56. After being refracted at the boundary between the inner surface of the transparent glass plate 51 and the liquid layer in the space 56,
The arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set such that the light is refracted on the inner surface of the transparent glass plate 52 and further refracted on the outer surface of the transparent glass plate 52 and received by the light receiving element 13. ing. Note that such a light path when a liquid is present in the space 56 is indicated by a solid line in FIG. 7B.

On the other hand, the path of light when there is no liquid in the space 56 is shown by a broken line in FIG. That is, the light emitted from the light emitting element 12 is
Is refracted on the outer surface of the transparent glass plate 51, enters the space 56, is refracted on the boundary surface between the inner surface of the transparent glass plate 51 and the gas layer in the space 56, and is then refracted on the inner surface of the transparent glass plate 52. Further, the light is refracted on the outer surface of the transparent glass plate 52 and irradiated to the outside. At this time, since the angle of refraction in the gas layer is larger than the angle of refraction in the liquid layer, light emitted from the outer surface of the transparent glass plate 52 to the outside passes through a position distant from the light receiving element 13.

That is, when there is a liquid in the space 56, the irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is no liquid in the space 56, the light emitting element 12
Are not received by the light receiving element 13.

In this embodiment, the light-emitting side optical path tube 62 is used.
The distal end of the light receiving side optical path tube 63 is formed at an angle along the outer surfaces of the transparent glass plate 51 and the transparent glass plate 52 so as to contact the outer surfaces of the transparent glass plate 51 and the transparent glass plate 52 without any gap. . That is, the light-emitting side optical path tube 62 and the light-receiving side optical path tube 63 also serve as the protection member according to the third aspect. By doing so, it is possible to prevent dust and dirt from adhering to the outer surfaces (optical path surfaces) of the transparent glass plates 51 and 52.

In FIG. 7 (a), two light-emitting side optical path tubes 62, 62 or light-receiving side optical path tubes 63, 63 are attached to one support plate 62a or 63a. One light-emitting side optical path tube 6 is provided for the plate 62a or 63a.
2 or the light receiving side optical path tube 63 may be attached. This is more convenient because each photoelectric liquid level detecting device 10 can be moved independently when the arrangement position of the photoelectric liquid level detecting device 10 in the height direction is changed.

FIGS. 8 (a), 8 (b) and 8 (c) show an air release pipe 65 in the middle of the photoelectric liquid level detector 10 of the present invention.
1 shows an embodiment applied to a see-through type sight glass 70 provided in FIG.

That is, the photoelectric type liquid level detecting device 10 shown here comprises a light emitting element 12 and a light emitting element 12 which are disposed at a constant incident angle and a constant refraction angle with respect to the outer surface of the transparent member of the transparent sight glass 70, respectively. A light receiving element 13, a fiber unit (indicated by a broken line) 14 for connecting the light emitting element 12 and the light receiving element 13, and an amplifier unit 15 connected to the fiber unit 14 for transmitting and receiving signals to and from a control panel 25; It has.

The control panel 25 has a relay R and a timer relay TR. The output of the amplifier unit 15 is connected to the air release valve 65 provided in the air release pipe 65 via the timer relay TR and the relay R. An electromagnetic valve or a motor valve) 66 is provided.

The timer relay TR is connected to the amplifier unit 1
When receiving the signal from 5, after counting a predetermined time, the air release valve 66 is controlled to close or open via the relay R.

The structure of the see-through type sight glass 70 is exactly the same as that of the conventional one, and as shown in FIG. 8C, two transparent glass plates 71 and 72 having a disk shape are horizontally opposed to each other. By inserting packings 75, 75 for stopping water and a spacer member 73 in the form of a short cylinder between opposing side edges of the transparent glass plates 71, 72, the transparent glass plates 71, 72 and the spacer member 73 are inserted. This forms a space 76 for a liquid pool. Also, the transparent glass plate 7
Pressing plates 78, 79 having through holes (viewing holes) are arranged on the outer surface sides (opposite to the space portion 76) of the first and second via the cushion members 77, 77, respectively. To the bolt 80 and the nut 81 [FIG.
See] and the holding plates 78, 79,
The transparent glass plates 71 and 72 and the spacer member 73 are integrally held and fixed.

The see-through sight glass 70 having such a structure is used.
In the present embodiment, a blind plate 82 provided with a light-emitting side optical path tube 84 is attached further outside the holding plate 78,
A blind plate 83 provided with a light receiving side optical path tube 85 is attached further outside the holding plate 79. Also, blind plates 82, 83
Are formed on the outer peripheral edge of the bolt.

That is, the bolt 80 is inserted between the bolt insertion hole 83a of the blind plate 83, the bolt insertion hole 79a of the holding plate 79, the bolt insertion hole 78a of the holding plate 78, and the bolt insertion hole 82a of the blind plate 82. , The two blind plates 82 and 83, the holding plates 78 and 79, the transparent glass plates 71 and 72, and the spacer member 73 are integrally held and fixed.

A holding member 87 for housing and holding the light emitting element 12 is screwed and fixed to the light emitting side optical path tube 84 attached to the blind plate 82. A holding member 88 that houses and holds the light receiving element 13 is screwed and fixed to the side optical path tube 85. The holding members 87, 88, the light-emitting side optical path tube 84, and the light-receiving side optical path tube 85
Is the same as that shown in FIG.
Here, the description is omitted.

The light-emitting-side light path tube 84 and the light-receiving-side light path tube 85 are arranged in the same horizontal plane.
Is such that the incident angle θ1 with respect to the outer surface of the transparent glass plate 71 is 90 ° or less (that is, the angle of incidence at the critical angle on the transparent glass plate 71; specifically, in the range of 10 ° to 60 °, more preferably). Is in the range of 20 ° to 50 °). The light receiving angle (refractive angle) θ2 of the light receiving side optical path tube 85 is the incident angle θ1 of the light emitting side optical path tube 84.
The angle is set to be equal to.

More specifically, in the present embodiment, in a state where the liquid is present in the space 76, the light emitted from the light emitting element 12 is refracted by the outer surface of the transparent glass plate 71 and enters the space 76. After being refracted at the boundary surface between the inner surface of the transparent glass plate 71 and the liquid layer in the space 76, it is refracted at the inner surface of the transparent glass plate 72,
The arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set so that the light is refracted by the outer surface of the light receiving element 2 and received by the light receiving element 13. Note that such a light path when a liquid is present in the space 76 is shown by a solid line in FIG. 8C.

On the other hand, the path of light when there is no liquid in the space 76 is indicated by a broken line in FIG. That is, the light emitted from the light emitting element 12 is
Is refracted by the outer surface of the transparent glass plate 72 and is incident on the inside of the space 76, and is refracted by the boundary surface between the inner surface of the transparent glass plate 71 and the gas layer in the space 76, and then refracted by the inner surface of the transparent glass plate 72. Further, the light is refracted on the outer surface of the transparent glass plate 72 and irradiated to the outside. At this time, since the angle of refraction in the gas layer is larger than the angle of refraction in the liquid layer, light emitted from the outer surface of the transparent glass plate 72 to the outside passes through a position distant from the light receiving element 13. That is, when there is a liquid in the space 76, the irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is no liquid in the space 76, the irradiation light from the light emitting element 12 is received The arrangement is such that the element 13 does not receive light.

In this embodiment, the light-emitting side optical path tube 84 is used.
And the front end of the light receiving side optical path tube 85 is
And the outer surface of the transparent glass plate 72 is not abutted. However, the space between the blind plate 82 and the transparent glass plate 71 and the space between the blind plate 83 and the transparent glass plate 72 are in a sealed state, and dust on the outer surfaces of the transparent glass plate 71 and the transparent glass plate 72 is kept. And adhesion of dust is prevented.

That is, in this embodiment, the light-emitting side optical path tube 8
4. The light receiving side optical path tube 85 and the blind plates 82 and 83 also serve as the protection member according to the third aspect.

FIGS. 9 (a), 9 (b) and 9 (c) show another embodiment of the mounting structure for mounting the light emitting element 12 and the light receiving element 13 of the photoelectric liquid level detecting device 10 to the transparent tube 11. . However, in FIG. 9A, the photoelectric liquid level detecting device 10 attached to the upper part of the transparent tube 11 is
6A and 6B show a modification of the structure of the photoelectric liquid level detecting device 10 shown in FIGS. 6A and 6B. The photoelectric liquid level detecting device 10 arranged below the transparent tube 11 is shown in FIGS. 9 shows a modification of the structure of the photoelectric liquid level detection device 10 shown in FIG.

That is, the transparent tube (glass tube in this embodiment) 11 is provided with a pair of protective materials 86, 86 opposed to each other over the entire length in the height direction. The photoelectric type liquid level detecting device 10 is attached to the upper and lower portions of 86, 86.

The upper photoelectric type liquid level detecting device 10 is mounted on a short cylindrical slide member 91 containing the transparent tube 11 and the protective materials 86, 86. Then, the slide member 91 is divided into a pair of divided pieces 92, 9 divided into right and left.
The arm pieces 92a, 93a extending outward are formed on both side edges of the divided pieces 92, 93, respectively. Further, these arm pieces 92a and 93a are provided with vertically elongated bolt insertion holes 92 at predetermined intervals in the vertical direction.
A plurality of sets b (93b is not shown) are formed (three sets in the present embodiment).

The divided pieces 92 and 9 of the slide member 91
3 is made to approach from both sides of the transparent tube 11, sandwiching the transparent tube 11 and the protective materials 86, 86, and contacting the two arm pieces 92a,
The slide member 91 can be pinched and fixed at an arbitrary position of the transparent tube 11 by inserting the bolt 94 into each of the bolt insertion holes 92b and 93b of the 93a and tightening with the nut 99. Further, since the bolt insertion holes 92b and 93b are formed in a vertically long shape, the two divided pieces 92 and 93 can be shifted up and down by the length of the bolt insertion holes 92b and 93b. That is, as described later, the light emitting element 12 and the light receiving element 13 can be finely adjusted in a mutual positional relationship.

Also, the light emitting element 1
A light-emitting-side light path tube 95 for screwing and fixing the light-receiving element 2 to form an optical path is provided, and a light-receiving-side light path tube 96 for screwing and fixing the light receiving element 13 to form an optical path is provided in the other divided piece 93. Have been. The light-emitting side light path tube 95 and the light-receiving side light path tube 96 are arranged in the same vertical plane, and
Means that the incident angle θ1 with respect to the outer surface of the transparent tube 11 is 90 °
The following (that is, the angle equal to or less than the angle of incidence at a critical angle on the transparent tube 11 in the same vertical plane passing through two opposing points of the transparent tube 11; specifically, in the range of 10 ° to 60 °, more preferably (In the range of 20 ° to 50 °). The light receiving angle (refraction angle) of the light receiving side optical path tube 96
θ2 is set to be equal to the incident angle θ1 of the light-emitting side optical path tube 95.

On the inner peripheral surfaces of the light-emitting side optical path tube 95 and the light-receiving side optical path tube 96, female screw portions 95a and 96a (96a is not shown) are formed, respectively.
On the other hand, the light emitting element 12 and the light receiving element 13 have external threaded portions 97a, 98a formed on the outer peripheral surface thereof, and holding members 97, screwed with hitting nuts 97b, 98b.
98, respectively. Also,
The nuts 97b and 98b are double nuts with washers 97c and 98c interposed.

Then, the male screw portion 97a of the holding member 97 accommodating and holding the light emitting element 12 is screwed into the female screw portion 95a of the light emitting side optical path tube 95 until the nut 97b comes into contact, so that the light emitting element 12 has a predetermined incident angle θ1. Fixed to
Male screw portion 9 of holding member 98 holding and holding light receiving element 13
8a until the nut 98b comes into contact with the light receiving side optical path tube 96.
Of the light receiving element 13
Is fixed to a predetermined light receiving angle (refraction angle) θ2.

That is, by simply screwing the holding member 97 containing the light emitting element 12 into the light emitting side optical path tube 95, the light emitting element 12
The position and angle of the light receiving element 13 can be set by simply screwing the holding member 98 containing the light receiving element 13 into the light receiving side optical path tube 96. The positional relationship between the light emitting element 12 and the light receiving element 13 can be set very easily as compared with the mounting structure described above.

On the other hand, as shown in FIGS. 9 (a) and 9 (c), the photoelectric liquid level detecting device 10 arranged below the transparent tube 11 is welded or bonded to the outer wall 1a of the liquid storage tank 1. It is attached to the supporting member 101 which is attached and fixed.

The support member 101 is a flat support body 10.
2 is formed in an L-shape in plan view with a flange portion 103 attached to the outer wall 1a of the liquid storage tank 1 formed on one side thereof. On the other hand, a pair of arms (a light-emitting side arm 104 and a light-receiving side arm 105) extending in parallel with a certain inclination angle are formed. A female screw portion 104a (not shown) for screwing and fixing a holding member 107 housing and holding the light emitting element 12 is formed on the light emitting side arm piece 104, and the light receiving element 13 is mounted on the light receiving side arm piece 105. Holding member 1 stored and held
A female screw portion 105a for screwing and fixing 08 is formed.

The light emitting side arm 104 is fixed to the support member 101 by welding or bonding. Light receiving arm 105
Is supported by bolts 111 and nuts 112 inserted through bolt insertion holes 105c provided in a flange portion 105b formed at the base end thereof and vertically elongated bolt insertion holes 102a provided in the support body 102. Member 101
It is fixed to. Since the bolt insertion hole 102a is formed in a vertically long shape, the light receiving side arm piece 105 can be shifted up and down by the length of the bolt insertion hole 102a.
That is, since the bolt insertion hole 102a is formed in a vertically long shape in parallel with the axis of the transparent tube 11, the mutual positional relationship between the light emitting element 12 and the light receiving element 13 can be finely adjusted as described later.

The female screw portion 104a and the female screw portion 105a are arranged on the same vertical plane passing through the axis of the transparent tube 11. The incident angle θ1 of the light emitting element 12 attached to the female screw portion 104a with respect to the surface of the transparent tube 11 is 90 °.
Female screw portion so as to be less than or equal to the angle of incidence at the critical angle to the transparent tube 11 (specifically, within the range of 10 ° to 60 °, more preferably within the range of 20 ° to 50 °). 1
04a is provided. Also, the light receiving angle (refraction angle) θ2 of the light receiving element 13 attached to the female screw portion 105a
The female screw portion 105a is provided so that the angle is equal to the incident angle θ1 of the light emitting element 12.

Here, the male screw portion 107a (not shown) of the holding member 107 holding and holding the light emitting element 12 is connected to the female screw portion 1 of the light emitting side arm piece 104 until the nut 107b abuts.
04a (not shown), the light-emitting element 1
2 can be fixed at a predetermined incident angle θ1. Further, by screwing the male screw portion 108a of the holding member 108 housing and holding the light receiving element 13 into the female screw portion 105a of the light receiving side arm piece 105 until the nut 108b abuts.
The light receiving element 13 can be fixed at a predetermined light receiving angle (refraction angle) θ2.

That is, simply by screwing the holding member 107 containing the light emitting element 12 into the light emitting side arm 104, the light emitting element 1
2 can be set, and the position and angle of the light receiving element 13 can be set only by screwing the holding member 108 containing the light receiving element 13 into the light receiving side arm piece 105.

Further, the bolt insertion hole 102a is formed vertically long, and the light receiving side arm piece 105 is connected to the bolt insertion hole 102a.
, The light emitting element 12 and the light receiving element 13 can be finely adjusted in mutual positional relationship. That is, when there is no liquid in the transparent tube 11 (or when there is a liquid), the light is emitted from the light emitting element 12 and the position where the light receiving element 13 receives light is determined. The arrangement position and the arrangement angle with the element 13 can be set very easily.

FIGS. 10A, 10B and 10C show modified examples of the photoelectric liquid level detecting device 10 shown in FIG.
That is, the light emitting element 12 and the light receiving element 13 arranged in the same horizontal plane in FIG. 8 are configured to be arranged in the same vertical plane in the present embodiment, and other configurations are illustrated in FIG. Since they are completely the same as those described above, the same reference numerals are given to the same members, and the detailed description is omitted. The light emitting element 12 and the light receiving element 13 are arranged in the same vertical plane, which is exactly the same as that of the embodiment shown in FIG. 9, but in the present embodiment, in FIG. The case where light is irradiated from the lower side to the upper left side is illustrated. Therefore, in FIG. 10C, the element arranged on the lower right is the light emitting element 12, and the element arranged on the upper left is the light receiving element 13.

That is, the light emitting element 12 and the light receiving element 13 are arranged in the same vertical plane, and the light emitting element 12
Is such that the incident angle θ1 with respect to the outer surface of the transparent glass plate 71 is 90 ° or less (that is, the angle of incidence at the critical angle on the transparent glass plate 71; specifically, in the range of 10 ° to 60 °, more preferably). Is in the range of 20 ° to 50 °). The light receiving angle (refractive angle) θ2 of the light receiving element 13 is set to be equal to the incident angle θ1 of the light emitting element 12.

In the present embodiment, in a state where the liquid exists in the space 76, the light emitted from the light emitting element 12 is received through the transparent glass plate 71, the liquid layer in the space 76, and the transparent glass plate 72. The arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set so that the light is received by the element 13 (the path of such light is shown by a solid line in FIG. 10C).

On the other hand, the path of light when there is no liquid in the space 76 is shown by a broken line in FIG. That is, the light emitted from the light emitting element 12 is
1, through the gas layer in the space 76 and the transparent glass plate 72,
Irradiation is performed from the outer surface of the transparent glass plate 72 to the outside. At this time, since the refraction angle in the gas layer is larger than the refraction angle in the liquid layer, light emitted from the outer surface of the transparent glass plate 72 to the outside passes through a position distant from the light receiving element 13. That is, when there is a liquid in the space 76, the irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is no liquid in the space 76, the irradiation light from the light emitting element 12 is received The arrangement is such that the element 13 does not receive light.

Further, in this embodiment, the tip portions of the light emitting element 12 and the light receiving element 13 are formed on the inclined surfaces attached to the outer surfaces of the transparent glass plates 71 and 72.
Thus, it is possible to prevent dust and dirt from adhering to the outer surfaces (optical path surfaces) of the transparent glass plates 71 and 72.

FIGS. 11A to 11D show modifications of the photoelectric liquid level detecting device 10 shown in FIG. That is, the light emitting element 12 arranged in the same horizontal plane in FIG.
In the present embodiment, the light-receiving element 13 and the light-receiving element 13 are arranged in the same vertical plane. Other configurations are the same as those shown in FIG. Almost the same configuration.

That is, the two vertically long transparent glass plates 12
1, 122 are opposed to each other, and packings 125, 125 for stopping water are located at the entire peripheral edges of both facing surfaces. Then, the opposing surfaces of the transparent glass plates 121 and 122 are formed into a vertically long space (slit) 1 of the spacer member 123.
26 are inserted into the recesses 123a on both sides of the transparent glass plate 26, respectively.
A space 126 for elevating and lowering the liquid is formed by the spacers 121 and 122, the spacer member 123, and the packings 125 and 125 for stopping water. In addition, cushion members 127 and 127 are located on the entire peripheral edge of the outer surface (the side opposite to the space 126) of the transparent glass plates 121 and 122, respectively.
129 are inserted into the recesses 128a, 129a inside the vertically long through holes (transparent windows) 128c, 129c, respectively, and both outer portions of the holding plates 128, 129 are stud bolt 130 and nuts 131, 131. And by tightening with the spring washer 132,
The holding plates 128 and 129, the transparent glass plates 121 and 122, and the spacer member 123 are integrally fixed.

Incidentally, bolt insertion holes 128b and 129b are formed on the entire periphery of the side edges of the holding plates 128 and 129, respectively. Here, the stud bolt 130 having the male screw portions 130a, 130a formed at both ends is inserted into the bolt insertion hole 12a.
8b, 129b, and presser plates 128, 129
Male threads 1 at both ends of stud bolt 130 projecting from
The nuts 131, 131 are screwed into the respective 30a, 130a, and tightened, so that the holding plates 128, 12
9, transparent glass plates 121, 122 and spacer member 12
3 is integrally fixed.

The stud bolt 130 and the nut 131,
As shown in FIG. 11 (a), a plurality of sets of the fasteners 131 are attached at predetermined intervals to the entire periphery of the side edges of the holding plates 128 and 129. However, instead of the stud bolts (headless bolts with screws at both ends) 130, long bolts (headed bolts) may be used. The holding plates 128 and 129 have vertically long transparent windows 1.
28c and 129c are formed, so that the liquid in the space 126 can be seen through the transparent glass plates 121 and 122.

In the liquid storage section (perspective liquid level meter) having such a structure, in the present embodiment, the light emitting element 12 is arranged outside one transparent glass plate 121 and the light receiving element 13 is connected to the other transparent glass plate. 122 is arranged outside.

That is, the light emitting element 12 and the light receiving element 13 are arranged in the same vertical plane.
Is the incident angle θ1 with respect to the outer surface of the transparent glass plate 121.
Is equal to or less than 90 ° (that is, equal to or less than the angle of incidence at the critical angle on the transparent glass plate 121; specifically, within the range of 10 ° to 60 °, more preferably within the range of 20 ° to 50 °). Are located in The light receiving angle (refractive angle) θ2 of the light receiving element 13 is set to be equal to the incident angle θ1 of the light emitting element 12.

In this embodiment, when there is no liquid in the space 126, the light emitted from the light emitting element 12 is received through the transparent glass plate 121, the gas layer in the space 126, and the transparent glass plate 122. The arrangement position and the arrangement angle of the light emitting element 12 and the light receiving element 13 are set so that the light is received by the element 13 [the path of such light is shown in FIG.
(Indicated by a solid line in (c)).

On the other hand, the light path when the liquid exists in the space 126 is shown by a solid line in FIG. That is, the light emitted from the light emitting element 12 is applied to the transparent glass plate 121, the liquid layer in the space 126, and the transparent glass plate 122.
Then, the light is radiated from the outer surface of the transparent glass plate 122 to the outside. At this time, since the angle of refraction in the liquid layer is smaller than the angle of refraction in the gas layer, light emitted from the outer surface of the transparent glass plate 122 to the outside passes through a position distant from the light receiving element 13. That is, when there is no liquid in the space 126, the irradiation light from the light emitting element 12 is received by the light receiving element 13, and when there is liquid in the space 126, the irradiation light from the light emitting element 12 is received. The arrangement is such that the element 13 does not receive light.

In the present embodiment, the optical path from the light emitting element 12 to the outer surface of the transparent glass plate 121 and the optical path from the outer surface of the transparent glass plate 122 to the light receiving element 13 are, for example, a rubber tube or a plastic tube, or The hermetically sealed state is maintained by an elastic protective member 139 such as putty. In this way, dust and dirt do not adhere to the outer surfaces of the transparent glass plates 121 and 122 protected by the protection member 139, the irradiating portion on the end face of the light emitting element 12, the light receiving section on the end face of the light receiving element 13, and the like. Therefore, there is no fear that light transmission is deteriorated. In addition, if it is completely sealed to prevent moisture in the atmosphere from entering into the protective member, the transparent glass plates 121 and 122 can be removed even under bad conditions such as high external temperature, cold liquid temperature, and high humidity. There is no risk of dew condensation on the light passage on the surface.

[0115]

As described above, according to the photoelectric liquid level detecting device of the present invention, since no lens is used, dust and dirt adhere to the surface of the lens and become cloudy, and the outside temperature, liquid temperature, humidity, etc. The liquid level can always be detected accurately without dew condensation on the lens surface depending on the condition (1). Also,
Since a shielding plate (light shielding plate) as in the conventional photoelectric type liquid level detecting device is not required, the number of parts can be reduced. In addition, in any state of the state where the liquid is in the liquid storage section or the state where there is no liquid, by irradiating light from the light emitting element and obtaining the position where the light receiving element receives light, the arrangement position of the light emitting element and the light receiving element and The arrangement angle can be set very easily. In other words, there is no need to dispose the shielding plate (light shielding plate) at a delicate position, and it is not necessary to project light at the exact critical angle of incidence from below the outside of the transparent body. Further, even if bubbles or the like are floating on the surface of the liquid, or if the liquid surface is raised or depressed due to surface tension, it can be detected without any trouble.

The photoelectric liquid level detecting device according to claim 2 of the present invention provides an optical path between the light emitting element and the outer surface of the light transmitting member and a light path between the light receiving element and the outer surface of the light transmitting member. Since it has a protection member that protects the optical path in a sealed state,
Dirt and dust can be reliably prevented from adhering to the outer surface of the light-transmitting member protected by the protective member, the illuminated portion on the end face of the light-emitting element, and the light-receiving section on the end face of the light-receiving element. There is no. In addition, by keeping the airtightly closed state so that moisture in the atmosphere does not enter the protective member, the light on the outer surface of the light transmitting member can be reduced even under bad conditions such as high external temperature, cold liquid temperature, and high humidity. There is no risk of condensation on the transmission part. Therefore, accurate liquid level detection can be performed over time. Also, a large cover member that covers the entire photoelectric liquid level detection device is not required.

Further, in the case of the present invention, since it is not necessary to bring the photoelectric liquid level detecting device into direct contact with the liquid, the liquid storage tank and the liquid storing portion for detecting the liquid level are made of a material such as plastic having high corrosion resistance. By using a material, even if the liquid has strong corrosiveness, the liquid level can be accurately detected continuously for a long time.

Further, since the light emitting element and the light receiving element are simply provided on the outer surface of the light transmitting member of the liquid storage part, the cost is low.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid storage tank to which a photoelectric liquid level detecting device of the present invention is applied.

FIGS. 2A and 2B show an embodiment of the arrangement position of the light emitting element and the light receiving element of the photoelectric liquid level detecting device according to the present invention. FIG. 2A shows light from the light emitting element when there is no liquid in the liquid reservoir. FIG. 4 is a horizontal cross-sectional view showing a configuration in which light is received by a light receiving element, and FIG. 4B is a horizontal cross-sectional view showing an optical path when a liquid is present in a liquid storage unit.

3A and 3B show another embodiment of the arrangement position of the light emitting element and the light receiving element of the photoelectric liquid level detecting device of the present invention, and FIG.
FIG. 3 is a horizontal cross-sectional view showing a configuration in which light from the light emitting element cannot be received by the light receiving element when there is no liquid in the liquid storage part, and FIG. 4B shows light from the light emitting element when liquid is present in the liquid storage part. FIG. 2 is a horizontal sectional view showing a configuration in which the light receiving elements are arranged to receive light.

4A and 4B show another embodiment of the mounting structure of the light emitting element and the light receiving element of the photoelectric liquid level detecting device of the present invention to the transparent tube, wherein FIG. 4A is a horizontal sectional view, and FIG. It is a perspective view.

5A and 5B show another embodiment of the mounting structure of the light emitting element and the light receiving element of the photoelectric liquid level detecting device of the present invention to the transparent tube, wherein FIG. 5A is a horizontal sectional view, and FIG. It is a perspective view.

6A and 6B show another embodiment of the mounting structure of the light emitting element and the light receiving element of the photoelectric liquid level detecting device of the present invention to the transparent tube, wherein FIG. 6A is a horizontal sectional view, and FIG. It is a front view.

7A and 7B show another embodiment of the photoelectric liquid level detecting device of the present invention, wherein FIG. 7A is a perspective view, and FIG. 7B is AA of FIG.
It is a line sectional view.

FIG. 8 shows an embodiment in which the photoelectric liquid level detecting device of the present invention is applied to a see-through sight glass provided in an air vent pipe in the middle of the pipe, and (a) is a pipe diagram including an electric circuit. (B) is a perspective view showing the photoelectric liquid level detecting device with a part cut away, and (c) is a sectional view taken along line BB of (a).

FIGS. 9A and 9B show another embodiment of the mounting structure for mounting the light emitting element and the light receiving element of the photoelectric liquid level detecting device of the present invention to the transparent tube, wherein FIG. 9A is a partially cutaway longitudinal sectional view, and FIG. 3 is a perspective view of a main part, and FIG. 3C is a cross-sectional view taken along line CC of FIG.

10 shows a modification of the photoelectric type liquid level detecting device shown in FIG. 8, wherein (a) is a piping diagram including an electric circuit, and (b)
3 is a perspective view of a main part, and FIG. 3C is a sectional view taken along line DD of FIG.

11A and 11B show a modified example of the photoelectric liquid level detecting device shown in FIG. 7, wherein FIG. 11A is a perspective view, and FIG.
FIG. 3C is a sectional view taken along line FF of FIG. 3A, and FIG. 3D is a sectional view taken along line FF of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid storage tank (storage tank) 10 Photoelectric liquid level detection apparatus 11 Transparent tube (liquid storage part) 12 Light emitting element 13 Light receiving element 29, 50 Protective member 30 Fixing member (protective member)

Claims (3)

[Claims] 1. A liquid storage section having a light transmitting member for detecting a liquid level, a light emitting element and a light receiving element arranged at the same incident angle and refraction angle with respect to the outer surface of the light transmitting member, respectively. An element, and only in one of a state in which liquid is present in the liquid storage part and a state in which there is no liquid, light emitted from the light emitting element is refracted by the outer surface of the light transmitting member and the liquid storage part has After entering the internal space and being refracted at the boundary surface between the inner surface of the translucent member and the liquid layer or gas layer in the internal space, reenters the light transmissive member and is refracted, and further, the light transmissive member The arrangement position and the arrangement angle of the light emitting element and the light receiving element are set so that the light is refracted by the outer surface of the light receiving element and received by the light receiving element. 2. A liquid storage unit having a light transmitting member for detecting a liquid level, a light emitting element and a light receiving element arranged at the same incident angle and refraction angle with respect to the outer surface of the light transmitting member, respectively. An element, and a protection member that protects an optical path between the light emitting element and the outer surface of the light transmitting member and an optical path between the light receiving element and the outer surface of the light transmitting member in a sealed state, Only in one of the state where the liquid is present in the liquid storage part or the state where there is no liquid, the light emitted from the light emitting element enters the internal space of the liquid storage part through the light transmitting member of the liquid storage part, and the liquid Through a liquid layer or a gas layer in the internal space of the storage portion, again through the light transmitting member, so as to be received by the light receiving element outside the light transmitting member, the light emitting element and the light receiving element The placement position and placement angle are set. Photoelectric type liquid level detecting device, characterized in that are. 3. The light-emitting device according to claim 1, wherein an incident angle of said light-emitting element is 10 ° to 6 °.
The photoelectric liquid level detecting device according to claim 1, wherein the angle is within a range of 0 °.