Float for liquid level detection

Abstract

[Problem] To provide a float for liquid level detection with which maintainability can be improved while performance as a float is maintained. [Solution] This float 1 for liquid level detection, capable of moving in a vertical direction along a guide member 22 provided in an underground tank 30, includes: a float body 2 formed from a foam molded body; and a cover part 3 covering an upper part of the float body. The upper surface of the cover part may be inclined with respect to the vertical direction, and a skirt part 4 projecting downward may be provided at the lower end of the float body. A notch that is open downward may be formed in the skirt part.

Description

Liquid level detection float

[0001] The present invention relates to a float for detecting a liquid level, and more particularly to a float used in a liquid level detection device for detecting the remaining amount of gasoline, diesel, kerosene, etc. in an underground tank.

[0002] Conventionally, magnetostrictive liquid level detection devices have been used to detect the remaining amount of gasoline, diesel, kerosene, etc. in underground tanks. In Patent Document 1 and the like, as shown in Fig. 4, a stem (guide member) 22 is inserted into an insertion hole 32 of a riser pipe 31 connected to the top surface of an underground tank 30, and a liquid level detection float (hereinafter, abbreviated as "float") 21 having a through-hole in its central axis is provided so as to be movable vertically along the stem 22, and the float 21 follows changes in the liquid level of the gasoline, etc. in the underground tank 30, and the remaining amount of gasoline, etc. in the underground tank 30 is detected by the magnetostrictive liquid level detection device or the like based on the position of the float 21.

[0003] Japanese Patent Application Laid-Open No. 2001-4434

[0004] The float 21 having the above-described configuration is suitable for quickly following changes in the liquid level, but when fuel oil is replenished into the underground tank 30 by a tank truck, sludge and the like that has accumulated below the underground tank 30 may fly up and get between the float 21 and the stem 22, thereby reducing the following ability of the float 21. Furthermore, sludge and the like may accumulate on the upper surface of the float 21, and its weight may reduce the buoyancy.

[0005] Furthermore, the body of the float 21 is formed from a foam having countless fine bubbles inside, and is lightweight and has high buoyancy performance. However, when the float body is pulled out of the underground tank for cleaning (maintenance) of the sludge, its upper part 21a comes into contact with the insertion hole 32 of the rising pipe 31 formed between the underground tank 30 and the ground, causing damage and making it unable to function as a float body, which requires replacement.

[0006] The present invention has been made in consideration of the problems in the prior art described above, and has as its object to provide a float for detecting liquid levels that maintains its performance as a float while improving maintainability.

[0007] In order to achieve the above-mentioned object, the present invention provides a liquid level detection float that can move vertically along a guide member installed in an underground tank, and is characterized by comprising a float body formed from a foam molded body and a cover portion that covers the top of the float body.

[0008] According to the present invention, the cover portion covers the top of the float body, so that when the float is pulled out from the underground tank, even if the cover portion comes into contact with the insertion hole of the rising pipe, damage to the float body can be prevented.

[0009] In the above-mentioned liquid level detection float, by tilting the upper surface of the cover part relative to the vertical direction, sludge does not accumulate on the cover part, which would reduce buoyancy, preventing a decrease in the ability to follow the liquid level and reducing the impact force on the float body.

[0010] In addition, by providing a skirt portion that protrudes downward at the lower end of the float body, it is possible to prevent sludge from entering the slider portion from the lower side of the float body, thereby preventing a decrease in the ability to follow the liquid surface.

[0011] Furthermore, by forming a notch that opens downward in the skirt portion, it is possible to induce the ingress of fuel oil from the bottom of the float body, thereby improving the ability to follow the liquid surface.

[0012] In addition, by removably winding a ballast string around the float body, the length and / or area (number of turns of the ring) of the ballast string can be changed, and by adjusting the mass of the float, the position of the center of buoyancy can be adjusted to be equal even in liquids of different densities.

[0013] By making the vertical position of the magnet attached to the float body adjustable, the position of the float's center of gravity can be changed, reducing the distance between the center of gravity and the center of buoyancy (restoring force), thereby improving the float's ability to follow the liquid surface.

[0014] As described above, according to the present invention, it is possible to provide a liquid level detection float that maintains the performance of the float while improving maintainability.

[0015] 1 is a diagram showing an embodiment of a liquid level detection float according to the present invention, where (a) is a perspective view and (b) is a cross-sectional view. FIG. 2 is a diagram showing details of the overall structure of the float of FIG. 1, where (a) is a cross-sectional view and (b) is an enlarged view of part A of (a). FIG. 3 is a diagram showing a state in which the liquid level detection float of FIG. 1 and a water detection float are in contact. FIG. 4 is a cross-sectional view showing an example of installation of a conventional liquid level detection float.

[0016] Next, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] As shown in Figure 1, the liquid level detection float 1 of the present invention is composed of a float body 2 formed from a foam molded body, a cover portion 3 covering the upper part of the float body 2, a skirt portion 4 attached to the lower end of the float body 2, sliders (convex portions) 5 and 6 protruding from the inner surface of a through hole 7 of the float 1, a magnet 8 attached to the float body 2, and a ballast string 9 wound around the float body 2, and is arranged to be movable vertically along a stem 22.

[0018] The float body 2 is formed of a foam having numerous fine bubbles inside, as in the conventional float body, and is lightweight and has high buoyancy.

[0019] The cover part 3 is made of a resin material that is more impact resistant than the float body 2, and is provided to cover the top of the float body 2. When the float 1 is pulled out from the underground tank 30 shown in Figure 4, the cover part 3 protects the head of the float body 2 when it hits the insertion hole 32 of the rising pipe 31, and the cover part 3 absorbs the impact, preventing damage to the float body 2. Furthermore, by tilting the upper surface 3a of the cover part 3 relative to the vertical direction, sludge does not accumulate on the upper part 21a of the float 21 (see Figure 3) and reduces buoyancy, as in the conventional case, and a decrease in the float's ability to follow the liquid surface can be prevented.

[0020] As shown in Figure 1, the skirt portion 4 protrudes downward from the lower end of the float body 2 and is provided to cover the entire circumference of the stem 22, which makes it difficult for sludge to enter the slider 6 from the lower side of the float body 2, preventing a decrease in the ability to follow the liquid surface. In addition, the skirt portion 4 is formed with a notch 4a that opens downward. As a result, as shown in Figure 3, even when the liquid level is low and the liquid level detection float 1 is sitting on the water detection float 10, fuel oil can easily enter from the bottom of the float body 2, improving the ability to follow the liquid surface.

[0021] The sliders 5 and 6 protrude from the inner circumferential surface of the through-hole 7 of the float 1 all around, and guide the float body 2 along the stem 22. By increasing the gap between these sliders 5 and 6 and the stem 22 (for example, increasing the gap between the sliders 5 and 6 and the stem 22 from a conventional gap of about 1 mm to about 2 mm), it becomes difficult for the sliders 5 and 6 to get caught on the stem 22, and it is possible to prevent the float body 2 from sinking completely. Note that the sliders 5 and 6 do not have to protrude from the inner circumferential surface of the through-hole 7 of the float 1 all around, but can also be provided discretely (intermittently) from the inner circumferential surface.

[0022] The magnet 8 is attached to the float body 2 in order to detect the liquid level by generating torsional distortion in the magnetostrictive wire. As shown in Figure 2, by adjusting the vertical position (8A, 8B) of the magnet 8, the position of the center of gravity of the float 1 can be changed, reducing the distance (restoring force) between the center of gravity and the center of buoyancy, and improving the float's ability to follow the liquid level.

[0023] Since malfunctions are particularly frequent when unloading, it is desirable to increase the volume of the float 1 when fully submerged and increase its buoyancy. However, increasing the diameter of the float 1 is limited by the diameter of the rising pipe 31, and there is also a limit to the minimum measurable liquid level, so there is also a limit to how far the float 1 can be extended in the longitudinal direction, i.e., how much buoyancy can be increased. Therefore, by adjusting the position of the magnet 8, the center of gravity and the center of buoyancy are brought closer together, reducing the restoring force (the force that keeps the float self-supporting), making it less likely for the float 1 to get caught on the stem 22.

[0024] In addition, by increasing the volume of the float body 2 that protrudes above the waterline, the float 1 is less likely to sink completely, and sludge is less likely to enter between the top of the float 1 and the stem 22, which is preferable.

[0025] Incidentally, the density of fuel oil is approximately 0.84 for diesel, 0.74 for gasoline, and 0.81 for kerosene, so if the float body 2 has the same volume and mass, diesel has a large buoyancy, so the length of the head floating above the water surface will be long, while gasoline has a small buoyancy, so the length of the head floating above the water surface will be short. In other words, if the float body 2 has the same volume and mass, as shown in Figure 1, if the liquid specific gravity is small, the draft position will approach the upper limit UL from the reference position RE, and if the liquid specific gravity is large, the draft position will approach the lower limit LL from the reference position RE.

[0026] The ballast string 9 shown in Figure 2(b) is detachably wound around the float body 2. By adjusting the length and / or area (number of turns of the ring) of this ballast string 9, the mass of the entire float 1 can be adjusted, and the position of the center of buoyancy can be adjusted to a constant value even for liquids of different densities.

[0027] In the above embodiment, the cover part 3 is provided to prevent damage to the float body 2, but instead of providing the cover part 3, the upper surface of the float body 2 can be inclined relative to the vertical direction and a paint that increases the strength can be applied to the upper surface to prevent damage to the float body 2.

[0028] The illustrated embodiments are merely examples and are not intended to limit the technical scope of the present invention.

[0029] REFERENCE SIGNS LIST 1 Liquid level detection float 2 Float body 3 Cover portion 3a Upper surface of cover portion 4 Skirt portion 4a Notch portion 5, 6 Slider 7 Through hole 8 Magnet 9 Ballast string 10 Water detection float 22 Stem (guide member)

Claims

1. A float for detecting liquid levels that can move vertically along a guide member installed inside an underground tank, the float comprising a float body made of a foam molded material, and a cover portion that covers the upper part of the float body.

2. The liquid level detection float according to claim 1, wherein the upper surface of the cover portion is inclined with respect to the vertical direction.

3. A liquid level detection float as claimed in claim 1 or 2, characterized in that the lower end of the float body is provided with a skirt portion that protrudes downward.

4. A liquid level detection float as claimed in claim 3, characterized in that said skirt portion is formed with a notch opening downward.

5. A liquid level detection float as claimed in claim 1 or 2, characterized in that a ballast ring is detachably wound around the float body.

6. The liquid level detection float according to claim 1 or 2, characterized in that the magnet attached to the float body is adjustable in vertical position.

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