JPH10185655A - Liquid level sensor, and liquid supplying device and liquid fuel combustion device using the level sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the abnormal combustion by idling when the emitting quantity of the light emitting element of a level sensor is insufficient in a petroleum fan heater. SOLUTION: A light emitting element 13 and a light receiving element 14 are buried within a light transmitting body 12 so that both the elements 13, 14 are mutually opposed, and the optical axis connecting both the elements 13, 14 is parallel to the level. The light transmitting body 12 is arranged within the fuel storing space 8 of a fuel tank so that a fuel detecting space 19 is formed on the optical axis. The light transmitting body 12 has a prism part 12c so that the light directed from the light emitting element 13 to the light receiving element 14 is totally reflected by the boundary surface with the fuel detecting space 19 without being directed to the light emitting element 14 when no liquid fuel is present in the fuel storing space 8. When no light is received by the light receiving element 14, it is detected that the liquid fuel in the fuel tank is reduced less than a prescribed level. Thus, it can be prevented that the liquid fuel in the fuel tank is erroneously recognized to be within the prescribed level in spite that it does not reach the prescribed level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level sensor for detecting a liquid in a liquid tank represented by a fuel tank of a liquid fuel combustion device such as an oil fan heater, and a liquid supply device using the liquid level sensor. The present invention relates to a liquid fuel combustion device.

[0002]

2. Description of the Related Art FIGS. 6A and 6B are principle views showing an operation mechanism of a conventional liquid level sensor, wherein FIG. 6A is a front view when liquid fuel is at a predetermined level, and FIG. It is a front view in the case.

Conventionally, as a liquid level sensor of this type, as disclosed in, for example, Japanese Patent Application Laid-Open No. 3-152308, attention is paid to the difference in refractive index between liquid fuel such as kerosene and air, and Snell's law is described. The ones used were known.

That is, in such a liquid level sensor, as shown in FIG. 6, a light emitting element 13 such as a light emitting diode and a light receiving element 14 such as a phototransistor are embedded in a transparent synthetic resin light transmitting body 12. Thus, the refractive index of the light transmitting body 12 is larger than the refractive index of air and smaller than the refractive index of the liquid fuel 15.

When the level of the liquid fuel 15 is higher than a predetermined level in the fuel tank, as shown in FIG.
Since the light transmitting body 12 is in a state of being immersed in the liquid fuel 15, the light emitted from the light emitting element 13 emits light.
The light passes through the boundary surface between the liquid fuel 15 and the liquid fuel 15 to the side having a higher refractive index, travels straight through the liquid fuel 15, and does not enter the light receiving element 14. As a result, the switching circuit connected to the light receiving element 14 is turned off, the electromagnetic pump is driven, and control is performed so that the liquid fuel 15 in the fuel tank is supplied to the burner and burned.

When the level of the liquid fuel 15 in the fuel tank becomes lower than a predetermined level, the light transmitting body 12 is exposed upward from the liquid fuel 15 as shown in FIG. Is in a state where air is present, so that the light emitted from the light emitting element 13 is totally reflected on the boundary surface between the light transmitting body 12 and the liquid fuel 15 and is incident on the light receiving element 14. As a result, the switching circuit connected to the light receiving element 14 is turned on, the driving of the electromagnetic pump is stopped, and the supply of the liquid fuel 15 to the burner is controlled to be stopped.

[0007]

However, the light emitting element 13
Usually, the amount of light emission decreases as the energizing time increases, and when the amount of light emission falls below a certain value, the amount of liquid fuel 15 in the fuel tank falls below a predetermined level. Nevertheless, there is a risk that the liquid fuel 15 is erroneously recognized as being at the predetermined level, and the electromagnetic pump is driven to perform idle operation in a state where the liquid fuel 15 has not reached the predetermined level, resulting in abnormal combustion. Was.

Further, even when the liquid fuel 15 is reduced below a predetermined level, the liquid fuel 15 adhered to the surface of the light transmitting body 12 tends to remain due to its surface tension.
There is a problem in that light is transmitted by the remaining liquid fuel 15 and erroneously determined that there is fuel.

In view of the above circumstances, the present invention provides a liquid level sensor, a liquid supply device, and a liquid fuel combustion which are highly safe in that the presence or absence of liquid can be accurately determined even if the light emission amount of the light emitting element is insufficient. It is intended to provide a device.

[0010]

That is, in the invention of the liquid level sensor of the present invention, the light emitting element and the light receiving element face each other,
In addition, the two elements are embedded in a light transmitting body so that the optical axis connecting the light emitting element and the light receiving element is parallel to the liquid surface, and the light transmitting body is formed such that a liquid detection space is formed on the optical axis. Is disposed in the liquid storage space of the liquid tank, and when there is no liquid in the liquid detection space, light traveling from the light emitting element to the light receiving element is totally reflected at a boundary surface with the liquid detection space and is directed to the light receiving element. A prism portion is provided on the translucent member so as not to face the light source, and when the light receiving element does not receive light, it is configured to detect that the liquid in the liquid tank has decreased below a predetermined level.

In addition, a light-emitting dark box is provided around the light-emitting element so as to guide the light emitted from the light-emitting element to the light-receiving element.

[0012] Further, a light emitting slit for limiting light emitted from the light emitting element to the light receiving element side is formed in the light emitting dark box.

Further, a light receiving dark box is provided around the light receiving element so as to guide the light passing through the liquid detection space and entering the light transmitting body toward the light receiving element.

Further, a light receiving slit for limiting light incident on the light transmitting body in the optical axis direction is formed in the light receiving dark box.

Further, according to the invention of the liquid supply apparatus of the present invention, the above-mentioned liquid level sensor and its light receiving element are mounted on a base of a liquid pump for sucking up liquid stored in a liquid tank and supplying it to a desired position. The device is mounted so as to be located at the same distance from the suction cylinder of the liquid pump.

Further, the above-mentioned liquid level sensor is mounted on a base of a liquid pump for sucking up the liquid stored in the liquid tank and supplying the liquid to a desired position. It is configured to be mounted far away.

Further, the invention of the liquid fuel combustion apparatus of the present invention detects the liquid fuel in the fuel tank, and supplies the liquid fuel to the burner when it is detected that the liquid fuel is at a predetermined level or more. The apparatus is configured by employing the above-described liquid supply apparatus.

[0018]

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

FIG. 1 is a perspective view showing an example of a petroleum fan heater which is a typical model of a liquid fuel combustion apparatus having a fuel tank as a liquid tank. FIG. 2 is an enlarged view showing the vicinity of the fuel tank of the petroleum fan heater shown in FIG. 3A and 3B are views showing an embodiment of the liquid level sensor according to the present invention, wherein FIG. 3A is a front view, FIG. 3B is a bottom view, and FIG. 4 is an enlarged view of the liquid level sensor shown in FIG. , (A) is a longitudinal sectional view, (b) is a view as viewed from an arrow A of (a), FIG. 5 is a principle view showing an operation mechanism of the liquid level sensor shown in FIG. FIG. 3B is a bottom view when the liquid fuel is not at a predetermined level, and FIG.

An oil fan heater 1 as a liquid fuel combustion device has a casing 2 as shown in FIG.
A warm air outlet 3 is formed on the front surface of the casing 2. A lid 5 is attached to the upper surface of the casing 2 so as to be openable and closable, and a fuel tank 6 is installed in the casing 2 below the lid 5. As shown in FIG. 2, a liquid fuel 15 such as kerosene is stored in a fuel storage space 8 in the fuel tank 6, and a cartridge tank 7 is removably mounted above the fuel tank 6. . An electromagnetic pump 9 is mounted on the upper surface of the fuel tank 6,
A liquid level sensor 10 is attached to the base 9b of the electromagnetic pump 9 downward so as to be parallel to the suction cylinder 9a. The electromagnetic pump 9, the liquid level sensor 10, and the liquid supply pipe (not shown) constitute a liquid supply device.

As shown in FIG. 3, the liquid level sensor 10 has a main body 11, and a transparent body 12 made of a transparent synthetic resin having a Π-shape is provided below the main body 11. . As shown in FIG. 4, a light-emitting dark box 16 made of a color hard to transmit light, for example, a black synthetic resin is embedded in the light-emitting legs 12 a of the light-transmitting body 12. 16a are formed. Further, a light emitting element 13 such as a light emitting diode is accommodated in the light emitting dark box 16. On the other hand, a light-receiving dark box 17 made of black synthetic resin is embedded in the light-receiving legs 12b of the translucent body 12,
The light receiving dark box 17 is formed with a vertically elongated light receiving slit 17 a facing the light emitting slit 16 a of the light emitting dark box 16. Further, a light receiving element 14 such as a phototransistor is accommodated in the light receiving dark box 17.

Here, as shown in FIG. 3, a prism portion 12c is provided on the light emitting leg portion 12a of the light transmitting body 12,
A fuel detection space 19 as a liquid detection space is formed on the optical axis connecting the photodetector 3 and the light receiving element 14 so as to communicate with the fuel storage space 8 in the fuel tank 6. I have.

Since the petroleum fan heater 1 has the above configuration, a predetermined level of the liquid fuel 1 is stored in the fuel tank 6.
5 is present only when the fuel is present, and in other cases (such as when the liquid fuel 15 in the fuel tank 6 falls below a predetermined level or when the light emitting element 13 becomes dark), 15 is not performed, and the liquid fuel 15 in the fuel tank 6 is supplied to the suction cylinder 9 a of the electromagnetic pump 9.
In this state, the idling of the oil fan heater 1 can be enhanced by preventing idle operation in a state where the oil fan heater 1 does not reach the limit and preventing abnormal combustion from occurring.

That is, when a predetermined level of the liquid fuel 15 is present in the fuel tank 6, the light transmitting body 12 of the liquid level sensor 10 is immersed in the liquid fuel 15 as shown in FIG. In this state, the light radiated from the light emitting element 13 passes through the prism portion 12 c of the light transmitting body 12 and the liquid fuel 1.
After being transmitted while refracting the boundary surface with 5 at a predetermined refraction angle,
The light travels straight through the liquid fuel 15 and passes through the boundary surface between the liquid fuel 15 and the light receiving leg 12 b of the light transmitting body 12 while being refracted at a predetermined refraction angle and enters the light receiving element 14. Therefore, the switching circuit connected to the light receiving element 14 is turned on, the electromagnetic pump 9 is driven, and the liquid fuel 15 in the fuel tank 6 is controlled to be supplied to a burner (not shown) and burn.

Since the light emitting element 13 and the light receiving element 14 of the liquid level sensor 10 are located at the same distance from the suction cylinder 9a of the electromagnetic pump 9, as shown in FIG.
The light emitted from the light emitting element 13 is not reflected by the suction cylinder 9a and does not cause a malfunction.

Moreover, the light emitted from the light emitting element 13 is guided not only to the light receiving element 14 by the light emitting dark box 16 itself, but also the light emitting direction is further limited to the light receiving element 14 side by the light emitting slit 16 a of the light emitting dark box 16. Therefore, the light is not emitted to a portion other than the light receiving element 14, and the directivity of the light to the light receiving element 14 can be improved. Also,
The light incident on the translucent body 12 is not only guided to the light receiving element 14 side by the light receiving dark box 17 itself, but also the light receiving direction is further limited by the light receiving slit 17a of the light receiving dark box 17 to the light receiving element 14 side. It is possible to avoid a situation in which light from a light source other than 13 or light reflected from another portion enters the light receiving element 14 and causes a malfunction.

When the liquid fuel 15 in the fuel tank 6 is consumed and becomes lower than a predetermined level, as shown in FIG. 5B, the light transmitting body 12 of the liquid level sensor 10
From the light-emitting element 13, most of the light radiated from the light-emitting element 13 passes through the boundary between the prism portion 12 c of the light-transmitting body 12 and the liquid fuel 15. The light does not transmit from the surface to the air layer side having a small refractive index, but is totally reflected at this boundary surface, and the light incident on the light receiving element 14 side is small. As a result, the switching circuit connected to the light receiving element 14 is turned off, the driving of the electromagnetic pump 9 is stopped, and the supply of the liquid fuel 15 to the burner is stopped.

If the light emission amount of the light emitting element 13 is reduced due to some reason (such as the life of the light emitting element 13), and the liquid fuel 15 in the fuel tank 6 drops significantly below a predetermined level, As in the case where the light emission amount of the light emitting element 13 is sufficient, the light radiated from the light emitting element 13 does not enter the light receiving element 14 side, so that the liquid fuel 15 in the fuel tank 6 drops significantly below a predetermined level. In spite of this, it is not mistaken that the liquid fuel 15 is at the predetermined level. Therefore, even if the amount of light emitted from the light emitting element 13 is insufficient, abnormal combustion due to idling can be avoided, and safety is excellent. On the other hand, when the liquid fuel 15 in the fuel tank 6 is at a predetermined level, the light emitting element 1
3, light emitted from the light emitting element 13 is incident on the light receiving element 14, but the amount of light received by the light receiving element 14 is also reduced due to insufficient light emission of the light emitting element 13. Although the liquid fuel 15 in the fuel cell 6 is at a predetermined level, it may be erroneously recognized that the liquid fuel 15 is significantly lower than the predetermined level. Does not occur.

The fuel detection space 1 formed on the optical axis
By providing the fuel cell 9, the liquid fuel 15 can be guided by its own weight so that the liquid fuel 15 hangs down along the surface of the light transmitting body 12 which is a boundary surface with the fuel detection space 19, The liquid remaining (accumulation) on the optical axis can be prevented from being suppressed, and erroneous determination that fuel is determined to be present even when the liquid fuel 15 has dropped below a predetermined level can be suppressed.

Further, both the light emitting element 13 and the light receiving element 14 are buried in the light transmitting body 12 so that the optical axis connecting the light emitting element 13 and the light receiving element 14 is parallel to the liquid surface. Therefore, the state of the liquid fuel 15 located in the fuel detection space 19 formed between the two elements 13 and 14, for example, the structure, boiling point and oxidation of molecules constituting kerosene such as good kerosene, bad kerosene, bad kerosene and altered kerosene It is possible to determine the state of kerosene that can be distinguished by discoloration due to the reaction. That is, if kerosene is oxidized and discolored, the transparency will decrease,
The light transmittance decreases, and the amount of light reaching the light receiving element 14 also decreases. Therefore, the state of the kerosene can be determined from the level change of the light quantity. Particularly, since bad kerosene and bad kerosene change (discolor) due to time change faster than good kerosene, it is also possible to discriminate between good kerosene and bad kerosene or bad kerosene by taking into account the passage of time.

In the above-described embodiment, in order to prevent the light emitted from the light emitting element 13 from being reflected by the suction cylinder 9a and causing a malfunction, the light emitting element 13 of the liquid level sensor 10 and the light receiving element Although the case where the element 14 and the element 14 are arranged at the same distance from the suction cylinder 9a of the electromagnetic pump 9 has been described, the same purpose can be achieved by making the light receiving element 14 farther from the suction cylinder 9a of the electromagnetic pump 9 than the light emitting element 13. It is also possible to achieve.

Although the liquid level sensor 10 of the oil fan heater 1 has been described in the above embodiment, the present invention can be applied to a liquid fuel combustion device other than the oil fan heater 1.

[0033]

As described above, according to the liquid level sensor of the present invention, the light emitting element and the light receiving element are opposed to each other, and the optical axis connecting the light emitting element and the light receiving element is at the liquid level. The two elements are embedded in a light-transmitting body so as to be parallel to the light-transmissive body, and the light-transmitting body is placed on the optical axis so that a liquid detecting space such as a fuel detecting space is formed on the optical axis. When light such as liquid fuel is not present in the liquid detection space, light traveling from the light emitting element to the light receiving element is totally reflected at a boundary surface with the liquid detection space when the liquid detection space does not have a liquid. A prism portion is provided on the translucent member so as not to go to the element, and when the light receiving element does not receive light, it is configured to detect that the liquid in the liquid tank has decreased below a predetermined level,
When the liquid in the liquid tank drops below a predetermined level, regardless of whether the light emitting element has sufficient light emission, light emitted from the light emitting element does not enter the light receiving element, Even if the liquid in the liquid tank is not at the predetermined level, it is not mistaken that the liquid is at the predetermined level. Even if the light emission amount of the light emitting element is insufficient, abnormal combustion due to idle operation can be avoided. Becomes

In addition, since a light-emitting dark box is provided around the light-emitting element so as to guide the light emitted from the light-emitting element to the light-receiving element side, in addition to the above-described effects, the light-emitting dark box is provided. The directivity of light to the light receiving element is increased.

Further, since the light emitting slit for limiting the light emitted from the light emitting element to the light receiving element side is formed in the light emitting dark box, in addition to the above-mentioned effects, the light emitting slit is limited to the light receiving element. The directivity of the light increases.

Further, since a light receiving dark box is provided around the light receiving element so as to guide the light passing through the liquid detection space and entering the light transmitting body toward the light receiving element,
In addition to the effects described above, the guidance by the light-receiving dark box prevents light from a light source other than the light-emitting element from being incident on the light-receiving element to cause a malfunction, thereby improving the reliability of the liquid level sensor.

Further, since the light receiving slit for limiting the light incident on the light transmitting body in the optical axis direction is formed in the light receiving dark box, in addition to the above-described effects, the light receiving slit restricts the light other than the light emitting element. The light from the light source does not enter the light receiving element to cause a malfunction, thereby improving the reliability of the liquid level sensor.

According to the liquid supply apparatus of the present invention, a liquid pump such as an electromagnetic pump for sucking up liquid such as liquid fuel stored in a liquid tank such as a fuel tank and supplying it to a desired position is provided. Since the liquid level sensor described above is mounted on the base such that the light emitting element and the light receiving element are located at the same distance from the suction cylinder of the liquid pump, light emitted from the light emitting element is It is possible to prevent the occurrence of a situation that is reflected by the suction cylinder and causes a malfunction.

The above-described liquid level sensor is mounted on a base of a liquid pump such as an electromagnetic pump which sucks up liquid such as liquid fuel stored in a liquid tank such as a fuel tank and supplies the liquid to a desired position. Also, the light receiving element is mounted so as to be far from the suction cylinder of the liquid pump, so that the light radiated from the light emitting element is reflected by the suction cylinder of the liquid pump to prevent the occurrence of a malfunction. It is possible to do.

Further, according to the invention of the liquid fuel combustion apparatus of the present invention, the liquid fuel in the fuel tank is detected, and when it is detected that the liquid fuel is at a predetermined level or more, the liquid fuel is supplied to the burner. Since the above-described liquid supply device is employed as the fuel supply device, the liquid fuel in the fuel tank is not at a predetermined level even though the liquid fuel is not at a predetermined level. Even if the light emission amount of the element is insufficient, abnormal combustion due to idle operation can be avoided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a petroleum fan heater which is a representative model of a liquid fuel combustion device having a fuel tank as a liquid tank.

FIG. 2 is an enlarged view of the vicinity of a fuel tank of the oil fan heater shown in FIG.

3A and 3B are diagrams showing one embodiment of a liquid level sensor according to the present invention, wherein FIG. 3A is a front view thereof, and FIG. 3B is a bottom view thereof.

4 is an enlarged view of the liquid level sensor shown in FIG. 3, (a)
Is a longitudinal sectional view thereof, and (b) is a view taken in the direction of arrow A in (a).

5A and 5B are principle diagrams showing an operation mechanism of the liquid level sensor shown in FIG. 3, wherein FIG. 5A is a bottom view when the liquid fuel is at a predetermined level, and FIG. It is a bottom view.

6A and 6B are principle views showing an operation mechanism of a conventional liquid level sensor, wherein FIG. 6A is a front view when liquid fuel is at a predetermined level, and FIG. 6B is a front view when liquid fuel is not at a predetermined level. It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid fuel combustion device (oil fan heater) 6 ... Liquid tank (fuel tank) 8 ... Liquid storage space (fuel storage space) 9 ... Liquid pump (electromagnetic pump) 9a ... Suction cylinder 9b ... Base 10 Liquid level sensor 12 Translucent body 12c Prism 13 Light emitting element 14 Light receiving element 15 Liquid (liquid fuel) 16 Light emitting dark box 16a Light emitting slit 17 Light receiving dark box 17a Light receiving slit 19 Liquid detection space (fuel detection space)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasunori Chiba 5-23-13 Ikegami, Ota-ku, Tokyo Inside Taisan Kogyo Co., Ltd. (72) Inventor Masatake Kimura 5-23-13 Ikegami, Ota-ku, Tokyo No. Taisho Kogyo Co., Ltd. (72) Katsumi Morito 2-5-5 Keihanhondori 2-chome, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Takeshi Osawa 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5-5 Sanyo Electric Co., Ltd. (72) Inventor Toshihiko Ujiie 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (8)

[Claims] 1. A light emitting element and a light receiving element face each other, and
The two elements are embedded in a translucent body such that the optical axis connecting the light emitting element and the light receiving element is parallel to the liquid surface, and the translucent body is liquid so that a liquid detection space is formed on the optical axis. It is arranged in the liquid storage space of the tank, and when there is no liquid in the liquid detection space, light traveling from the light emitting element to the light receiving element is totally reflected at the boundary surface with the liquid detection space and does not go to the light receiving element A liquid level sensor for detecting that the liquid in the liquid tank has decreased below a predetermined level when the light receiving element does not receive light. 2. The liquid level sensor according to claim 1, wherein a light-emitting dark box is provided around the light-emitting element so as to guide light emitted from the light-emitting element toward the light-receiving element. 3. The liquid level sensor according to claim 2, wherein a light emitting slit for limiting light emitted from the light emitting element to the light receiving element side is formed in the light emitting dark box. 4. A light receiving dark box is provided around the light receiving element so as to guide the light passing through the liquid detection space and entering the light transmitting body toward the light receiving element. The liquid level sensor according to any one of the above. 5. The liquid level sensor according to claim 4, wherein a light receiving slit for limiting light incident on the light transmitting body in the optical axis direction is formed in the light receiving dark box. 6. A base of a liquid pump for sucking up liquid stored in a liquid tank and supplying the sucked liquid to a desired position.
6. A liquid supply device, wherein the liquid level sensor according to any one of claims 1 to 5 is mounted such that its light emitting element and light receiving element are located at the same distance from the suction cylinder of the liquid pump. . 7. A base of a liquid pump for sucking up liquid stored in a liquid tank and supplying the sucked liquid to a desired position.
6. A liquid supply device, wherein the liquid level sensor according to any one of claims 1 to 5 is mounted such that the light receiving element is farther from the suction cylinder of the liquid pump than the light emitting element. 8. A fuel supply device for detecting liquid fuel in a fuel tank and supplying the liquid fuel to a burner when it is detected that the liquid fuel is at or above a predetermined level.
A liquid fuel combustion device, comprising the liquid supply device according to claim 7.