JP2014044155A - Float type liquid surface level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a float type liquid surface level detector which hardly brings about a chattering phenomenon even in the case of the occurrence of rippling on a liquid surface of and has a simple structure to be superior in terms of a manufacturing cost.SOLUTION: In the float type liquid surface level detector, a magnet float having a magnetic property is inserted so as to move vertically along an outer periphery of a substantially perpendicularly installed stem, and the change in a liquid surface level of a target detection liquid is detected by the change in the position of the magnet float. The flow type liquid surface level detector includes a cover member which is provided to cover the magnet float and forms a space for liquid surface detection, a liquid inlet is formed in a lower end-side part of the cover member, an air outlet is formed in an upper surface part of the cover member, and the air outlet is provided with a valve mechanism for discharging air in one direction from the inside of the cover member to the outside.

Description

  The present invention relates to a float type liquid level detection device that detects a liquid level from a change in the position of a magnet float that has magnetism, and more specifically, to a sudden fluctuation of the liquid level such as a ripple or inclination of the liquid level. The present invention also relates to a float type liquid level detecting device that can stably detect the liquid level.

  Conventionally, as a mechanism for detecting the liquid level, a float that detects a change in the liquid level by detecting a change in the position of the float using a float that floats on the liquid level. The device is known.

FIG. 5 is a schematic configuration diagram showing an example of a conventional liquid level detecting device.
As shown in FIG. 5, the conventional liquid level detection device 100 includes a substantially cylindrical stem 102, a magnetic float 104 having magnetism, and a magnetic sensitive element 106 that is turned on when the magnetic float 104 comes close. And a lead wire 108 for taking out a signal from the magnetic sensitive element 106.

  The magnetic float 104 is formed in a ring shape having a through-hole in the center, and the stem 102 is inserted into the through-hole, and is arranged in a state that can move up and down along the stem 102. Further, the magnetic float 104 is formed to have a specific gravity smaller than that of a liquid for detecting the liquid level (hereinafter referred to as “detected liquid”).

  The liquid level detecting device 100 configured as described above is attached to a container in which a liquid to be detected is stored in a substantially vertical shape. Since the magnetic float 104 floats on the liquid level of the liquid to be detected, the liquid level changes in this state, for example, when the liquid level reaches a predetermined position by increasing or decreasing, The magnetic sensitive element 106 is turned ON, and an ON signal is output via the lead wire 108. Thus, it can be detected that the liquid level of the liquid to be detected has reached a predetermined position.

  However, when a conventional float type liquid level detector is used for equipment with large vibrations, such as transportation equipment, the liquid surface is undulated by vibration, so the float moves up and down due to the influence of the undulations. End up. In this case, a chattering phenomenon in which the magnetic sensitive element incorporated in the liquid level detecting device repeats ON-OFF occurs, and there is a problem that the liquid level cannot be accurately detected.

  In order to solve this problem, there is known a float type liquid level detecting device that reduces the influence of ripples by covering the float with a cylindrical tube having an inner diameter slightly larger than the outer diameter.

  Further, as in Patent Document 1 (Japanese Patent Laid-Open No. 52-88060), a cap having an integrated valve mechanism is attached to the upper end of the liquid level detection device, and the cap is deformed manually. In addition, a liquid level detection device has also been proposed in which the inside of the case is kept airtight and is not affected by undulations.

JP-A-52-88060

However, even if the float is simply covered with a cylindrical tube, even if an air discharge hole and a liquid introduction port are provided and the shape and size thereof are devised, the influence of undulation cannot be sufficiently reduced.
In addition, the liquid level detection device disclosed in Patent Document 1 is suitable for specific gravity detection and liquid level detection of battery fluid of transport equipment, but it is necessary to make the inside of the case airtight by manual operation. Further, since the structure is complicated and the manufacturing cost is high, it is not suitable as a liquid level detecting device used for inexpensive equipment.

  In view of such a current situation, the present invention provides a float type liquid level detecting device that is less likely to cause chattering even when a liquid level undulation occurs, has a simple structure, and is excellent in terms of manufacturing cost. The purpose is to do.

The present invention has been invented in order to solve the problems in the prior art as described above, and the float type liquid level detection device of the present invention has a magnet float having magnetism arranged substantially vertically. A float type liquid level detecting device that is intubated to move up and down along the outer periphery of the stem and detects a change in the liquid level of the liquid to be detected from a change in the position of the magnet float,
A cover member is provided so as to cover the magnet float and forms a liquid level detection space,
A liquid inlet is formed in the lower end side portion of the cover member, and an air discharge hole is formed in the upper surface portion,
The air discharge hole is provided with a valve mechanism for discharging air in one direction from the inside of the cover member to the outside.

  The valve mechanism is composed of a flat valve body and a shaft foot having a drop prevention portion, and can be arranged to insert the shaft foot into the air discharge hole.

  Further, the valve mechanism may be constituted by a plate member, and the plate member may be disposed on the outer surface of the cover member so as to block the air discharge hole, and one side of the plate member may be fixed.

The float type liquid level detecting device of the present invention comprises a repelling means for generating a repulsive force on the lower surface side of the magnet float,
Suction means for generating a suction force on the upper surface side of the magnet float;
It is preferable to further comprise.

  Preferably, the attracting means is an attracting magnet that forms an attracting magnetic field with respect to the magnetic pole of the magnet float, and the repelling means is a repelling magnet that forms a repelling magnetic field with respect to the magnetic pole of the magnet float. It is preferable that

  According to the present invention, it is possible to obtain a float type liquid level detecting device that has a simple structure and is excellent in manufacturing cost. With this device, it is possible to cope with rapid fluctuations in the liquid level such as undulation or inclination of the liquid level. In addition, the liquid level can be detected stably.

  Furthermore, by providing suction means and repulsion means on the upper surface side and lower surface side of the magnet float respectively, the stability of the magnet float is improved, and the liquid level is more stable without being affected by undulations. Can be detected.

FIG. 1 is a schematic cross-sectional view of an example of the liquid level detecting device of the present invention. FIG. 2 is a schematic configuration diagram showing an example of a valve mechanism of the liquid level detecting device of FIG. FIG. 3 is a schematic configuration diagram showing another embodiment of the valve mechanism. FIG. 4 is a schematic cross-sectional view of another embodiment of the liquid level detecting device of the present invention. FIG. 5 is a schematic cross-sectional view of an example of a conventional liquid level detecting device.

Hereinafter, embodiments (examples) of the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an example of the liquid level detecting device of the present invention.
As shown in FIG. 1, the liquid level detecting device 10 of this embodiment includes a substantially cylindrical stem 12, a magnet float 14 having magnetism, and a magnetic sensitivity in which a switch is turned on when the magnet float 14 comes close. An element 16, a lead wire 18 for taking out a signal from the magnetic sensing element 16, and a cover member 24 covering the magnet float 14 are provided.

  The stem 12 is integrally formed with a threaded portion 12b at the upper end portion of the flange portion 12a. The stem 12 is substantially vertical to a container (not shown) in which the liquid to be detected is stored via, for example, a packing and a nut (not shown). It is attached to the shape.

As the magnetic sensitive element 16, for example, a reed switch can be used, and the magnetic sensitive element 16 and the lead wire 18 are electrically connected by a method such as soldering.
Further, as the magnetically sensitive element 16, an ON signal may be output when the magnet float 14 approaches, or an OFF signal may be output.

  The magnetic sensitive element 16 is disposed at a predetermined position in the stem 12, and the lead wire 18 includes, for example, an insulating means 32 such as a bushing, and a molding material 34 such as an epoxy resin for the purpose of forming a waterproof and drip-proof structure. It is fixed by.

  One end portion of the lead wire 18 is led out of the stem 12 and connected to a control circuit (not shown). As will be described later, when the ON signal or the OFF signal from the magnetic sensitive element 16 is detected by the control circuit, it is detected that the liquid level of the liquid to be detected has changed.

The magnet float 14 is not particularly limited, and a known magnet float can be used. As such a magnet float, for example, a so-called foamed plastic float in which a sintered magnet and a plastic foam are integrally molded, a sintered magnet and a rubber foam such as nitrile rubber (NBR) are integrally molded. Examples include so-called foamed NBR float, so-called metal float in which a sintered magnet is incorporated in a hollow metal, and unfoamed resin float made of a resin and a magnet.
Among these, since liquid does not penetrate into the float and has excellent chemical resistance, powders such as ferrite magnets such as strontium ferrite and rare earth magnets are used as plastic resin materials having chemical resistance. From the viewpoint of performance and magnetic characteristics, an unfoamed magnet float obtained by mixing a suitable amount of strontium ferrite powder and injection-molding it into a ring shape is desirable. When this unfoamed magnetic float is used, it is preferable to provide an apparatus having a structure as shown in FIG. 4, for example, provided with means for floating the float on the liquid to be detected.

The cover member 24 is provided so as to cover the magnet float 14 and has a role as a case. The interior of the cover member 24 is a liquid level detection space 23.
The material of the cover member 24 is not particularly limited, but a material such as plastic that does not block the magnetic flux of the magnet is preferable. In addition, what interrupts | blocks the magnetic flux of magnets, such as a metal, can be used by selecting the member which comprises a detection apparatus suitably according to a use.

  The cover member 24 has a liquid inlet 24a formed at the lower end side portion thereof, and an air discharge hole 24b formed at the upper surface portion thereof.

  The size of the liquid introduction port 24a is not particularly limited as long as the liquid to be detected can enter and exit the cover member 24. If the size of the liquid introduction port 24a is too small, as will be described later, It becomes difficult to discharge the liquid to be detected due to the surface tension of the liquid to be detected.

  On the other hand, even if the size of the liquid introduction port 24a is too large, as will be described later, when the liquid introduction port 24a is exposed to the air, the liquid to be detected inside the cover member 24 suddenly increases from the liquid introduction port 24a. It will be discharged.

  For this reason, it is necessary to appropriately select the shape and size of the liquid inlet 24a in accordance with the properties such as the viscosity, specific gravity, and temperature characteristics of the liquid to be detected and the usage environment.

  The air discharge hole 24b is provided with a valve mechanism 25 for discharging air in one direction from the inside of the cover member 24 to the outside.

  The size of the air discharge hole 24b is not particularly limited as long as it is a size that can discharge air in one direction from the inside of the cover member 24, and may be appropriately selected according to the structure of the valve mechanism 25 and the like. As shown in FIG. 2, the valve mechanism 25 includes a flat valve body 25a and a shaft foot 25b having a drop prevention portion 25c, and the shaft foot 25b is inserted into the air discharge hole 24b. In this case, the diameter of the air discharge hole 24b is larger than the diameter of the shaft leg 25b, and even when the shaft leg 25b is inserted into the air discharge hole 24b, there is a gap that allows the air inside the cover member 24 to be smoothly discharged to the outside. Furthermore, it is preferable that the size is such that friction does not occur with the air discharge hole 24b when the shaft foot 25b moves.

  In the liquid level detector 10 in which the valve mechanism 25 of the present embodiment is configured as shown in FIG. 2, the liquid to be detected enters the cover member 24 and rises to a position where the liquid closes the liquid inlet 24a. Until this is done, the valve mechanism 25 closes the air discharge hole 24b with the valve body 25a by its own weight. On the other hand, when the liquid level of the liquid to be detected rises to a position where it covers the liquid inlet 24a, the inside of the cover member 24 is in an airtight state. Therefore, when the liquid level rises as it is, the air inside the cover member 24 is automatically opened by the valve mechanism 25 and the air inside the cover member 24 is discharged to the outside.

  At this time, in order for the air inside the cover member 24 to push up the valve mechanism 25 to open the valve mechanism 25, a force greater than the self-weight of the valve mechanism 25 + the adhesion force of the liquid to be detected is required. It is desirable that the valve mechanism 25 be as light as possible.

  In addition, in the present embodiment, the four drop prevention portions 25c are provided, but the valve mechanism 25 has a structure that can block the air discharge hole 24b or smoothly discharge air as described above. In addition, the valve mechanism 25 may be structured so as not to be detached from the cover member even when the inside of the cover member 24 is filled with the liquid to be detected. As another example, the valve mechanism 25 has at least two drop prevention portions 25c. More stably, there may be mentioned one in which three drop prevention portions 25c are provided at intervals of 120 ° with respect to the shaft leg 25b.

  The slip prevention part 25c is 10 ° to 15 ° upward from the horizontal (that is, a state inclined by 75 ° to 80 ° with respect to the shaft foot 25b), so that the valve mechanism 25 can be easily inserted into the air discharge hole 24b. In addition, it is desirable because the drop prevention part 25c comes into contact with the inner surface of the cover member 24 by point contact.

  The material of the valve mechanism 25 is not particularly limited. For example, rubber or plastic can be used. In addition, the valve body 25a and the shaft foot 25b may be formed integrally, or may be formed separately and the valve body 25a and the shaft foot 25b may be fixed to form the valve mechanism 25. When the valve body 25a and the shaft foot 25b are separated, the valve body 25a and the shaft foot 25b may be made of the same material or different materials.

  In the embodiment shown in FIG. 1, the valve mechanism 25 includes a valve body 25a, a shaft foot 25b, and a drop prevention portion 25c. However, the present invention is not limited to this. For example, FIG. As shown in FIG. 4, a plate member 36 made of a flat rubber plate or a plastic thin plate is disposed so as to block the air discharge hole 24b on the outer surface of the cover member 24, and one side of the plate member 36 is fixed, so-called A valve mechanism 25 having a cantilever spring structure can be obtained.

  Such a valve mechanism 25 is opened when the liquid level of the liquid to be detected rises above the position where the liquid inlet 24a is blocked and the air pressure inside the cover member 24 rises, and the air inside the cover member 24 is The shape and the structure of the valve mechanism 25 are not limited as long as the cover member 24 is closed and the liquid to be detected is filled with the liquid to be detected.

  Reference numeral 38 denotes a protective cover for protecting the plate member 36, and reference numeral 38 a denotes a passage hole provided in the protective cover 38.

  In this embodiment, from the lower surface to the upper surface inside the cover member 24 is a movable range in which the magnet float 14 can move up and down, and the position where the lower surface of the magnet float 14 is closest to the lower surface inside the cover member 24 is the magnet. The “lower end position” of the float 14 and the position where the upper surface of the magnet float 14 is closest to the upper surface inside the cover member 24 are the “upper position” of the magnet float 14.

  In the present embodiment, the magnetic sensitive element 16 is disposed in the vicinity of the upper end position of the magnet float 14, and when the magnet float 14 reaches the vicinity of the upper end position as the liquid level increases, via the lead wire 18. An ON signal is output.

  In the liquid level detecting device 10 of this embodiment configured as described above, the liquid level inside the container rises and the liquid to be detected enters the cover member 24 from the liquid level introduction hole 24a, so that the magnet float When 14 reaches the upper end position, the magnetic sensitive element 16 is kept in the ON state.

  In this state, even if severe undulations occur, the valve mechanism 25 keeps the inside of the cover member 24 airtight, and it is difficult for air to flow into the cover member 24 through the liquid inlet 24a and the air discharge hole 24b. The magnet float 14 is unlikely to move up and down due to the influence of waves, and the liquid level can be detected stably.

  Further, even if the container to which the liquid level detection device 10 is attached is inclined and the liquid inlet 24a is exposed to the air, the liquid to be detected inside the cover member 24 is rapidly discharged from the liquid inlet 24a. Since the magnet float 14 maintains the same position, the magnetic sensitive element 16 is kept in the ON state, and the liquid level can be detected stably.

  When the liquid level of the liquid to be detected descends and reaches slightly below the upper end position of the liquid inlet 24a, the liquid to be detected inside the cover member 24 is drawn out by the surface tension of the liquid to be detected, and the same amount Air enters from the liquid inlet 24a. As a result, the liquid level inside the cover member 24 is lowered, and the magnet float 14 is also lowered and separated from the magnetic sensitive element 16, so that the magnetic sensitive element 16 is turned off.

FIG. 4 is a cross-sectional view of another embodiment of the liquid level detecting device of the present invention.
Since the liquid level detecting device 10 of this embodiment has basically the same configuration as the liquid level detecting device 10 shown in FIG. 1, the same reference numerals are given to the same components, Detailed description thereof is omitted.

  In this embodiment, a repulsion magnet 20 is provided as a repelling means for generating a repulsive force on the lower surface side of the magnet float 14, and a suction magnet 22 is provided as a suction means for generating an attractive force on the upper surface side of the magnet float 14. Is provided.

  The magnet float 14 is magnetized in the thickness direction so as to have a polarity corresponding to the repulsion magnet 20 and the attraction magnet 22. In this embodiment, in FIG. 4, the magnet float 14 is magnetized so that the upper surface side is the S pole and the lower surface side is the N pole.

  In the present embodiment, the repulsion magnet 20 forms a repulsion magnetic field with respect to the magnetic poles of the magnet float 14, and in this embodiment, the cover member is such that the upper surface side of the repulsion magnet 20 is the N pole and the lower surface side is the S pole. It is being fixed to the lower surface side of 24 so that it may not drop.

  Further, in this embodiment, the attracting magnet 22 forms a attracting magnetic field with respect to the magnetic pole of the magnet float 14, and in this embodiment, the cover member is formed so that the upper surface side of the repelling magnet 22 is the S pole and the lower surface side is the N pole. It is fixed to the upper surface side of 24 so as not to drop off.

  The repulsion magnet 20 and the attraction magnet 22 are not particularly limited. For example, a plastic magnet, a rubber magnet, a sintered magnet, a rare earth magnet, and the like can be used. The shape of the attracting magnet 22 is not particularly limited.

  As shown in FIG. 4, when the repulsion magnet 20 and the attraction magnet 22 are provided outside the cover member 24, a material that does not block the magnetic flux of the magnet, such as plastic, is selected as the material of the cover member 24. There is a need to.

  Although not shown, the repulsion magnet 20 and the attraction magnet 22 can be provided inside the cover member 24.

  When the liquid level detecting device 10 of the present embodiment is used in, for example, a generator having a magnetic source such as a magnet inside the device, the magnet float 14, the repulsive magnet 20, The cover member 24 blocks the magnetic flux of the magnet so as not to affect the magnetic flux of the attracting magnet 22 and to prevent the magnet float 14 and the magnetic sensitive element 16 from being affected by the magnetic source. It is preferable to configure.

  In the liquid level detecting device 10 of the present embodiment configured as shown in FIG. 4, a repulsive force is generated on the lower surface side of the magnet float 14, and an attractive force is generated on the upper surface side of the magnet float 14.

  For this reason, even if the liquid level rises and the gap between the magnet float 14 and the repulsion magnet 20 becomes larger and the repulsive magnetic force due to the repulsion magnet 20 becomes smaller, the gap between the magnet float 14 and the attracting magnet 22 becomes smaller. , The attractive magnetic force by the attractive magnet 22 is increased, and the additional buoyancy with respect to the magnet float 14 is sufficiently provided, so that the magnet float 14 can be stabilized.

  In order to sufficiently give the additional buoyancy to the magnet float 14, the shape and magnetic force of the magnet float 14, the repulsion magnet 20, and the attracting magnet 22 are appropriately selected so as to satisfy the condition expressed by the following formula (1). It is preferable.

F> A−C × G Formula (1)
However,
F is the combined force (g weight) of the repulsive force of the repulsive magnet 20 and the attractive force of the attracting magnet 22 when the magnet float 14 is in the movable range;
A is the weight (g weight) of the magnet float 14;
C is the volume (cm ³ ) of the magnet float 14;
G is the density of the liquid to be detected (g weight / cm ³ ),
And

  Further, in order to move the magnet float 14 up and down in accordance with the change in the liquid level of the liquid to be detected, the magnet float 14, the repulsion magnet 20, and the attraction for satisfying the condition expressed by the following formula (2) It is preferable to select the shape and magnetic force of the magnet 22 as appropriate.

F ′ <A Formula (2)
However,
F ′ is a combined force (g weight) of the repulsive force of the repulsive magnet 20 and the attractive force of the attracting magnet 22 when the magnet float 14 is in the upper end position.
A is the weight (g weight) of the magnet float 14;
And

  The combined force that satisfies the expressions (1) and (2) is a necessary buoyancy for floating the magnet float 14 on the liquid to be detected. By selecting in this way, the magnet float 14 can be floated on the liquid level of the liquid to be detected, and the magnet float 14 moves up and down the movable range in the stem 12 as the liquid level of the liquid to be detected changes. Will do.

  If the combined force F of the repulsive force of the repulsive magnet 20 and the attractive force of the attracting magnet 22 when the magnet float 14 is at the lower end position is greater than the weight A of the magnet float 14, the magnet float 14 is It does not come into close contact with the repulsion magnet 20 and floats at a position where the resultant force F and the weight A are balanced.

For this reason, the movable range of the magnet float 14 is lower than the lower surface to the upper surface inside the cover member 24, and the lower surface of the magnet float 14 in a state where it floats from the lower surface inside the cover member 24 at a position where the combined force F and weight A are balanced. Therefore, the liquid level detection range becomes narrow, which is not preferable.
Therefore, it is preferable that the synthetic force F satisfies the following formula (3).

A>F> A-C × G Formula (3)
However, F, A, C and G are the same as described above.

By extending the entire length of the stem 12, the liquid level detection range can be widened, but the design tends to be complicated and the manufacturing cost tends to increase.
By selecting the magnetic force of the magnet float 14, the repulsion magnet 20, and the attracting magnet 22 so as to satisfy the expression (3), the magnet float 14 can accurately move up and down as the liquid level of the liquid to be detected changes. In addition, the movable range of the magnet float 14 can be maximized.

  In the liquid level detecting device 10 of this embodiment configured as described above, the liquid level inside the container rises and the liquid to be detected enters the cover member 24 from the liquid level introduction hole 24a, so that the magnet float When 14 reaches the upper end position, the magnetic sensitive element 16 is kept in the ON state.

  In this state, even if severe undulations occur, the valve mechanism 25 keeps the inside of the cover member 24 airtight, and it is difficult for air to flow into the cover member 24 through the liquid inlet 24a and the air discharge hole 24b. The magnet float 14 is unlikely to move up and down due to the influence of waves, and the liquid level can be detected stably.

  Further, even if the container to which the liquid level detection device 10 is attached is inclined and the liquid inlet 24a is exposed to the air, the liquid to be detected inside the cover member 24 is rapidly discharged from the liquid inlet 24a. Since the magnet float 14 maintains the same position, the magnetic sensitive element 16 is kept in the ON state, and the liquid level can be detected stably.

  When the liquid level of the liquid to be detected descends and reaches slightly below the upper end position of the liquid inlet 24a, the liquid to be detected inside the cover member 24 is drawn out by the surface tension of the liquid to be detected, and the same amount Air enters from the liquid inlet 24a. As a result, the liquid level inside the cover member 24 is lowered, and the magnet float 14 is also lowered and separated from the magnetic sensitive element 16, so that the magnetic sensitive element 16 is turned off.

  In addition, when using such a liquid level detection apparatus 10 for detecting the liquid level of lubricating oil, such as transportation equipment and a generator, for example, in the lubricating oil as the usage time of the equipment elapses. Magnetic metal powder may be mixed.

  In this case, there is a problem that affects the life of the equipment, so there is a possibility that it is usually necessary to replace the filter or the lubricating oil. However, in the liquid level detecting device 10 as shown in FIG. The metal powder is attracted to the repulsion magnet 20 and the suction magnet 22 of the liquid level detection device 10.

  Thus, since the magnetic metal powder in the liquid to be detected such as lubricating oil can be removed by the repulsion magnet 20 and the suction magnet 22 of the liquid level detection device 10, the liquid level detection device 10 is attached. Longer service life is expected.

  In addition, since magnetic metal powder adheres to the magnet float 14 very little, magnetic metal powder mixes between the magnet float 14 and the stem 12, and the movement of the magnet float 14 is not hindered. .

  As mentioned above, although one Example of this invention was described, this invention is not limited to this, For example, the opposing relationship of the magnetic pole of the magnet float 14, the repulsion magnet 20, and the attraction magnet 22 is shown in this Example. It can also be attached to be opposite to each other.

  In the embodiment shown in FIG. 4, the repulsion magnet 20 and the attraction magnet 22 are used as the repulsion means and the attraction means. However, the present invention is not limited to this. As shown in 160561, a spring structure can also be used.

  Furthermore, the present invention is not limited to transportation equipment, and can be used for, for example, detecting the liquid level of a container used for equipment that generates vibration or inclination, such as a small generator or agricultural equipment. Various modifications can be made without departing from the object.

DESCRIPTION OF SYMBOLS 10 Liquid level detection apparatus 12 Stem 12a Flange part 12b Screw part 14 Magnet float 16 Magnetosensitive element 18 Lead wire 20 Repulsion magnet 22 Suction magnet 23 Liquid level detection space 24 Cover member 24a Liquid inlet 24b Air discharge hole 25 Valve mechanism 25a Valve body 25b Shaft foot 25c Disengagement prevention part 32 Insulating means 34 Mold material 36 Plate member 38 Protective cover 38a Passage hole 100 Liquid level detecting device 102 Stem 104 Magnetic float 106 Magnetic sensitive element 108 Lead wire

Claims (4)

A float type liquid that intubates a magnet float with magnetism so that it moves up and down along the outer periphery of a stem arranged substantially vertically, and detects a change in the level of the liquid to be detected from a change in the position of the magnet float A surface level detection device,
A cover member is provided so as to cover the magnet float and forms a liquid level detection space,
A liquid inlet is formed in the lower end side portion of the cover member, and an air discharge hole is formed in the upper surface portion,
The float type liquid level detecting device, wherein the air discharge hole is provided with a valve mechanism for discharging air in one direction from the inside of the cover member to the outside.   2. The valve mechanism according to claim 1, wherein the valve mechanism includes a flat valve body and a shaft foot having a slip-off preventing portion, and is disposed so as to insert the shaft foot into the air discharge hole. The float type liquid level detecting device described.   The said valve mechanism is comprised by the board member, While arrange | positioning this board member so that the said air exhaust hole may be plugged up in the outer surface of the said cover member, the one side of the said board member was fixed. The float type liquid level detecting device described. Repulsion means for generating a repulsive force on the lower surface side of the magnet float;
Suction means for generating a suction force on the upper surface side of the magnet float;
The float type liquid level detecting device according to any one of claims 1 to 3, further comprising:

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