JP7565427B2 - Liquid level detection unit for drainage equipment - Google Patents

Description

The present invention relates to a liquid level detection unit for drainage equipment.

In recent years, flooding has occurred in many areas due to climate change. The occurrence of flooding is increasing year by year, and the scale of disasters is also growing. For example, when a sudden torrential downpour occurs, a large amount of rainwater on the road will flow into sewers, rivers, and roadside gutters. If the amount of water that flows in exceeds expectations, it may overflow from the sewers, rivers, and roadside gutters, causing damage such as the interruption of transportation networks and flooding of homes.

For example, a friction type liquid level detection device (liquid level detection unit) is known that is provided in a tubular member extending vertically inside a sewage tank (drainage equipment) that stores wastewater such as sewage and rainwater, and that includes a hanging rope and multiple float switches (liquid level sensors) (see, for example, Patent Document 1). The liquid level detection device is fixed inside a case that is hollow inside. The float switch turns on when tilted upward beyond a predetermined operating angle set above the horizontal, and detects a predetermined allowable liquid level (warning liquid level).

JP 2012-26109 A

Incidentally, detecting changes in the liquid level in rainwater manholes installed around houses is also important in detecting the occurrence of flood damage. Rainwater manholes are fitted with a lattice-like cover, such as a grating. Through the grating, more rainwater than expected can flow into the manhole. When the liquid level rises suddenly, a float switch such as that described in Patent Document 1 can be subjected to a buoyant force that pushes the float switch vertically.

Therefore, the present invention was made in consideration of the above problems, and aims to provide a technology that makes it easier for a float-type liquid level sensor to tilt and float up.

In order to solve the above problem, the liquid level detection unit of the present invention comprises a float-type liquid level sensor that is suspended via a cable within a drainage facility and detects when the liquid level has reached a predetermined level, and a support section that extends in the extension direction of the cable within the drainage facility and supports the liquid level sensor via the cable so that it can float, and the liquid level sensor is characterized in that, when supported by the support section, the extension direction of an axis that extends from one end to which the cable is connected to the other end opposite the cable intersects with the extension direction of the cable.

In one aspect of the present invention, the liquid level detection unit includes an extended support part connected to the lower end of the support part in the hanging direction of the liquid level sensor, and a float-type second liquid level sensor supported on the extended support part via a cable separate from the cable so that it can float and detects when the liquid level reaches a predetermined liquid level below the predetermined liquid level. When the second liquid level sensor is supported on the extended support part, the extension direction of an axis extending from one end to which the cable is connected to the other end opposite the cable may intersect with the extension direction of the other cable.

In addition, in a liquid level detection unit according to one aspect of the present invention, the support part and the extended support part are plate-shaped members, and at least one of the support part and the extended support part has a pair of protruding plates that protrude toward the liquid level sensor and the second liquid level sensor along each edge extending in the hanging direction, and the pair of protruding plates are spaced apart from each other so as to only allow the liquid level sensor and the second liquid level sensor to float in a direction away from the support part and the extended support part.

In addition, in the liquid level detection unit according to one aspect of the present invention, at least one of the support portion and the extended support portion may have a plurality of fixing positions that enable fixing of the cable and the other cable in the hanging direction of the liquid level sensor and the second liquid level sensor.

In addition, the liquid level detection unit according to one aspect of the present invention may include a mounting portion that extends vertically from the support portion to the side on which the liquid level sensor is supported at the upper end of the support portion in the hanging direction of the liquid level sensor and is attached to the drainage equipment.

Furthermore, in order to solve the above problem, the liquid level detection unit according to the present invention comprises a cylindrical member having one end closed and the other end open, a short axis and a long axis in a cross section perpendicular to the extension direction, a pair of short axis sidewalls opposing each other in the direction of the short axis, and a float-type liquid level sensor that is suspended from one end of the cylindrical member to the other end via a cable and housed within the cylindrical member and detects when the liquid level reaches a predetermined liquid level, the cable that suspends the liquid level sensor is attached to one of the pair of long axis sidewalls, and the axis of the liquid level sensor that extends from one end of the liquid level sensor to which the cable is connected to the other end opposite the cable is inclined from one side of the long axis sidewalls toward the other side of the long axis sidewalls.

In addition, in a liquid level detection unit according to one aspect of the present invention, the spacing between the pair of short axis side walls may be set to prevent the liquid level sensor from floating up along the short axis, and the spacing between the pair of long axis side walls may be set to allow the liquid level sensor to float up along the long axis and detect the predetermined liquid level.

In addition, in a liquid level detection unit according to one aspect of the present invention, the cylindrical member has at least one hole on the side of the one end relative to the liquid level sensor when the liquid level sensor is suspended.

In addition, in a liquid level detection unit according to one aspect of the present invention, the closed end of the tubular member has at least one first rib that protrudes along the short axis side wall portion to the side opposite the other end, and at least one second rib that protrudes along the long axis side wall portion to the side opposite the other end, and the at least one first rib and the at least one second rib are capable of supporting a fastener that fastens the tubular member to the drainage equipment.

In addition, the liquid level detection unit according to one aspect of the present invention further includes a float-type second liquid level sensor that is suspended below the liquid level sensor from one end of the tubular member to the other end via a cable separate from the cable and is housed within the tubular member, and detects when the liquid reaches another predetermined liquid level below the liquid level detected by the liquid level sensor.

In addition, in a liquid level detection unit according to one aspect of the present invention, an axis extending from one end of the second liquid level sensor to which the cable is connected along the other end opposite the cable is inclined from the other side of the long axis side wall portion toward one side of the long axis side wall portion.

In addition, in the liquid level detection unit according to one aspect of the present invention, a guide path is formed on the other longitudinal side wall portion to guide the other cable at a position that does not contact the liquid level sensor in a raised state.

In addition, in the liquid level detection unit according to one aspect of the present invention, the cylindrical member is provided with a stopper that is provided between the liquid level sensor and the second liquid level sensor in the hanging direction and prevents the second liquid level sensor from floating up toward the liquid level sensor relative to a position corresponding to the other predetermined liquid level.

In addition, in a liquid level detection unit according to one aspect of the present invention, the cross-sectional shape of the liquid level sensor intersecting an axis extending from one end of the liquid level sensor to which the cable is connected along the other end opposite the cable is circular.

According to the present invention, the liquid level of a float-type liquid level sensor is more likely to tilt and float up.

FIG. 1A is an oblique view from above of a liquid level detection unit according to a first embodiment of the present invention attached to a grating, and FIG. 1B is an oblique view from below of the liquid level detection unit attached to a grating. 1 is a perspective view of a liquid level detection unit according to a first embodiment of the present invention; 1A is a perspective view of the plate unit as viewed from above, and FIG. 1B is a perspective view of the plate unit as viewed from below. 1A and 1B are diagrams for explaining the configuration of a liquid level sensor according to a first embodiment of the present invention, where FIG. 1A is a perspective view of the liquid level sensor, and FIG. FIG. 4 is a side view showing a state in which a liquid level sensor is attached to the plate unit. 1A and 1B are diagrams for explaining the operation of a liquid level detection unit according to a first embodiment of the present invention, in which (a) is a diagram showing the initial state of the liquid level sensor, and (b) is a diagram showing the state in which the liquid level sensor floats on the liquid surface and detects the warning liquid level. FIG. 11 is a perspective view of a liquid level detection unit according to a modified example of the first embodiment of the present invention. FIG. 4 is a diagram for explaining dimensions of a plate unit and a liquid level sensor. FIG. 11 is a perspective view of a liquid level detection unit according to a second embodiment of the present invention. FIG. 11 is a side view of a liquid level detection unit according to a second embodiment of the present invention. 11A and 11B are diagrams for explaining the operation of a liquid level detection unit according to a second embodiment of the present invention, in which (a) is a diagram showing the initial state of the liquid level sensor, and (b) is a diagram showing a state in which the liquid level sensor is floating on the liquid surface and is tilted to detect the liquid level. 1A is an oblique view for explaining the configuration of a rainwater manhole to which a liquid level detection unit in a third embodiment of the present invention is attached, and FIG. 1B is a cross-sectional view of the rainwater manhole taken along line bb in FIG. FIG. 13 is a transparent perspective view of a liquid level detection unit according to a third embodiment of the present invention. 4A and 4B are perspective views of the cover, in which FIG. 4A is a perspective view of the cover seen from above, and FIG. 4B is a perspective view of the cover seen from below. FIG. FIG. 4 is a cross-sectional view showing a state in which the liquid level sensor is attached to the cover. 11 is a diagram for explaining dimensions of a cover and a liquid level sensor. FIG. FIG. 4 is a cross-sectional view showing the state in which the liquid level detection unit is attached to the grating. 11A and 11B are diagrams for explaining the operation of a liquid level detection unit according to a third embodiment of the present invention, in which (a) is a diagram showing the initial state of the liquid level sensor, (b) is a diagram showing the state in which the liquid level sensor is floating on the liquid level WL, prior to detecting the warning liquid level K, and (c) is a diagram showing the state in which the liquid level sensor is tilted to detect the warning liquid level. 13A and 13B are perspective views illustrating the configuration of a liquid-level detection unit according to a fourth embodiment of the present invention, where FIG. 21 is a cross-sectional view of the liquid level detection unit taken along line XI-XI in FIG. 20(b). 13A and 13B are diagrams for explaining the operation of a liquid level detection unit according to a fourth embodiment of the present invention, in which (a) is a diagram showing the initial state of the liquid level sensor, (b) is a diagram showing the state in which the liquid level sensor is floating on the liquid surface and before detecting the liquid level, and (c) is a diagram showing the state in which the liquid level sensor is tilted to detect the liquid level.

Below, an embodiment of the present invention will be described with reference to the drawings.

First Embodiment
The liquid level detection unit 1A according to the first embodiment of the present invention is attached to, for example, a grating 122 of a drainage facility such as a street gutter for draining rainwater. The liquid level detection unit 1A detects that the liquid level in the rainwater tank has reached a predetermined liquid level (hereinafter also referred to as a "warning liquid level") K1 when water exceeding the allowable amount enters the drainage facility and the water level (liquid level) rises. The liquid level detection unit 1A is applied to, for example, a known drainage facility, and the drainage facility to which it is applied is not limited to a specific drainage facility. For example, the liquid level detection unit 1A according to the embodiment of the present invention is attached to a lattice-shaped grating 122 provided in the drainage facility shown in FIG. 1.

Figure 1(a) is a perspective view from above of a liquid level detection unit 1A according to a first embodiment of the present invention attached to a grating 122, and Figure 1(b) is a perspective view from below of the liquid level detection unit 1A attached to the grating 122.

The liquid level detection unit 1A according to this embodiment, which is attached to the grating 122, includes a float-type liquid level sensor 20 that is suspended from the drainage equipment via a cable 30 and detects when the liquid level WL reaches a predetermined liquid level K1, and a support portion (hereinafter also referred to as a "support plate") 12A that extends in the extension direction of the cable 30 within the drainage equipment 100 and supports the liquid level sensor 20 so that it can float via the cable 30. When the liquid level sensor 20 is supported by the support portion 12A, the extension direction of the axis x1 that extends from one end 21 to which the cable 30 is connected to the other end 22 opposite the cable 30 intersects with the extension direction of the cable 30. The configuration of the liquid level detection unit 1A will be specifically described below.

[Liquid level detection unit]
2 is a perspective view of a liquid-level detection unit 1A according to a first embodiment of the present invention. The liquid-level detection unit 1A is attached to a grating 122 of a drainage facility from the inside. The liquid-level detection unit 1A is attached to the grating 122 via a stainless steel fastener 101. The liquid-level detection unit 1A includes a plate unit 10A, a liquid-level sensor 20, a cable 30, and a power supply unit 40.

(Plate unit)
3A and 3B are perspective views of the plate unit 10A, where (a) is a perspective view of the plate unit 10A seen from above, and (b) is a perspective view of the plate unit 10A seen from below. The plate unit 10A is formed by a mounting plate 11A and a support plate 12A. The plate unit 10A is a member in which the mounting plate 11A and the support plate 12A are connected to each other so as to be L-shaped or approximately L-shaped. The mounting plate 11A and the support plate 12A are connected to each other via two metal angle members 13A.

The mounting plate 11A is a plate member that is rectangular in plan view and is made of synthetic resin, metal, or the like. The mounting plate 11A can be supported on the grating 122 via a stainless steel fastener 101. The mounting plate 11A has multiple insertion holes 14A. The fastener 101 is passed through the insertion holes 14A and attached to the grating 122.

The support plate 12A is a plate member that is rectangular in plan view and is made of synthetic resin, metal, or the like. The support plate 12A is attached at right angles to the mounting plate 11A via an angle member 13A. The support plates 12A are connected to each other with one short side butting against the short side of the mounting plate 11A. The support plate 12A extends vertically to the grating 122. The support plate 12A supports the liquid level sensor 20 via a cable 30.

The support plate 12A has multiple pairs of insertion holes 15A along the longitudinal direction. The multiple pairs of insertion holes 15A are provided at predetermined intervals along the longitudinal direction and serve as fixing positions for the cable 30. The liquid level sensor 20 is supported on the cable 30 by a band-shaped fastener 31 so that it can float on the support plate 12A.

(Liquid level sensor and cable)
4 is a diagram for explaining the configuration of the liquid level sensor 20, where (a) is a perspective view of the liquid level sensor 20 and (b) is a side view of the liquid level sensor 20. The liquid level sensor 20 is a float-type sensor. The liquid level sensor 20 is suspended from the plate unit 10A by a cable 30. The liquid level sensor 20 is supported on the support plate 12A by the cable 30 being fixed to the support plate 12A. As the liquid level rises, the liquid level sensor 20 detects a warning liquid level K1 by tilting one end 21 to which the cable 30 is connected so as to approach the other end 22 opposite the cable 30 in the suspension direction H along the vertical direction.

The liquid level sensor 20 has a weight (not shown), a sphere (not shown), a microswitch (not shown), etc. inside. The liquid level sensor 20 functions as a float, and has a mass greater than its buoyancy. The liquid level sensor 20 is not particularly limited, and a known float-type sensor can be used.

The cross-sectional shape of the liquid level sensor 20 along the axis x1 passing through the center of the liquid level sensor 20 is teardrop-shaped or approximately teardrop-shaped. The cross-sectional shape of the liquid level sensor 20 intersecting the axis x1 is circular or approximately circular. The diameter 20R of the cross-sectional shape of the liquid level sensor 20 increases continuously from one end 21 to the other end 22 along the axis x1, from the tip 21 side where the cable 30 is attached.

The length 20L of the liquid level sensor 20 along the axis x1 is greater than the maximum diameter Rmax of the liquid level sensor 20. In other words, the diameter 20Rmax of the liquid level sensor 20 is smaller than the length 20L of the liquid level sensor 20. It is preferable that the length 20L of the liquid level sensor 20 is 1.30 to 1.40 times the maximum diameter Rmax.

Figure 5 is a side view showing the liquid level sensor 20 attached to the plate unit 10A. The cable 30 that suspends the liquid level sensor 20 is fixed to the support plate 12A. The cable 30 is attached from the upper side of the support plate 12A of the plate unit 10A in the hanging direction H. The liquid level sensor 20 is switched on when the axis x1 extending from the tip 21 through the center of the base end (other end) 22 on the opposite side to the tip 21 in the hanging direction H approaches a horizontal state, for example.

The cable 30 is electrically connected to the liquid level sensor 20. The cable 30 extends from the mounting plate 11A side along the support plate 12A. One end of the cable 30 is connected to the tip 21 side of the liquid level sensor 20. The other end of the cable 30 is connected to a power supply unit 40 provided behind the support plate 12A.

The cable 30 extends along the support plate 12A. The cable 30 is attached to the support plate 12A with a belt-shaped fastener 31 at a position spaced a predetermined distance from the liquid level sensor 20. For example, the cable 30 is fixed to the support plate 12A by inserting one end of the fastener 31 through one of a pair of insertion holes 15A of the support plate 12A and leading it out from the other insertion hole 15A.

The cable 30 is supported so that it can move around the fixed point P1, which is fixed by the fastener 31, in a direction away from the support plate 12A. The cable 30 is movable in the area between the fixed point P1 and the tip 21 of the liquid level sensor 20. The position of the fixed point P1 may be set, for example, so that the liquid level sensor 20 can make the axis x1 of the liquid level sensor 20 horizontal.

The liquid level sensor 20 is partially in contact with the support plate 12A while being suspended from the support plate 12A via the cable 30. When the liquid level sensor 20 is attached to the support plate 12A, the axis x1 extending from one end 21 along the other end 22 of the liquid level sensor 20 intersects with the extension direction of the cable 30. The axis x1 of the liquid level sensor 20 also intersects with the support plate 12A. The liquid level sensor 20 is supported by the support plate 12A such that the axis x1 is away from the support plate 12A on the base end 22 side with respect to the tip 21.

The liquid level sensor 20 detects that the liquid level WL has reached the warning level K1 by floating on the liquid level WL in a direction away from the support plate 12A and tilting so that the axis x1 of the liquid level sensor 20 approaches a horizontal state. In other words, when the liquid level sensor 20 detects the warning level K1, the liquid level sensor 20 floats on the liquid level WL and the tip 21 of the liquid level sensor 20 approaches the base end 22 in the hanging direction H, shortening the distance between the tip 21 and the base end 22.

(Power supply)
The power supply unit 40 is attached to the support plate 12A on the side opposite to the liquid level sensor 20. A cable 30 is electrically connected to the power supply unit 40. The power supply unit 40 supplies electricity to the liquid level sensor 20 via the cable 30.

[Operation of the liquid level detection unit]
6A and 6B are diagrams for explaining the operation of the liquid level detection unit 1A according to the first embodiment of the present invention, in which (a) is a diagram showing the initial state of the liquid level sensor 20, and (b) is a diagram showing the state in which the liquid level sensor 20 floats on the liquid level WL and detects the warning liquid level K1. For example, heavy rain may cause an unexpected amount of rainwater to flow into the drainage equipment through the grating 122. This causes the liquid level WL in the drainage equipment to rise (see FIG. 6A).

The warning level K1 of the liquid level WL detected by the liquid level sensor 20 is set arbitrarily at a position spaced a predetermined distance h from the grating 122 along the hanging direction H of the liquid level sensor 20. When the liquid level WL reaches the warning level K1, it is an indication that there is a risk of water spilling out of the grating 122, for example. For example, the liquid level sensor 20 is configured to detect the liquid level at a predetermined height position from the base end 22. By adjusting the length of the cable 30 and appropriately changing the hanging position of the liquid level sensor 20, the predetermined height position from the base end 22 passing through the axis x1 can be made to correspond to the arbitrarily set warning level K1.

As the amount of rain flowing in through the grating 122 increases, the liquid level WL reaches the base end 22 of the liquid level sensor 20, and the liquid level sensor 20 begins to float up. The liquid level sensor 20 tilts together with the cable 30 and floats up, away from the support plate 12A.

The mass of the liquid level sensor 20 is greater than the buoyancy. In the liquid level sensor 20, the center of buoyancy is on the base end 22 side, and the center of gravity of the liquid level sensor 20 is located on the tip end 21 side. Therefore, due to the misalignment between the center of buoyancy and the center of gravity, a rotational moment is generated in the liquid level sensor 20. Due to the generation of the rotational moment, as the liquid level WL rises, the tip 21 of the liquid level sensor 20 tilts, and in the hanging direction H, the tip 21 of the liquid level sensor 20 approaches the base end 22 side, and the axis x1 approaches horizontal or approximately horizontal (see FIG. 6(b)).

When the liquid level WL reaches the warning level K1, for example, when the axis x1 of the liquid level sensor 20 exceeds a predetermined angle with the support plate 12A, the internal sphere rolls and the microswitch turns on. The liquid level sensor 20 sends a signal to an external device to warn that the liquid level WL in the drainage equipment has reached the warning level K1.

By attaching the above-described liquid level detection unit 1A to drainage equipment, it is possible to recognize the possibility of flood damage occurring in advance. According to the liquid level detection unit 1A, the liquid level sensor 20 is attached to the support plate 12A together with the cable 30 with the axis x1 tilted relative to the extension direction of the cable 30. Therefore, when the liquid level WL rises to the base end 22, the liquid level sensor 20 floats up, not vertically, but away from the support plate 12A together with the cable 30 below the fixed point P1. This makes the liquid level sensor 20 more susceptible to buoyancy, allowing the liquid level sensor 20 to float up smoothly.

In addition, since the support plate 12A has a plurality of pairs of insertion holes 15A spaced at a predetermined interval along the longitudinal direction, the position of the fixing point P1 of the cable 30 relative to the support plate 12A can be appropriately selected. For example, if the distance between the tip 21 of the liquid level sensor 20 and the fixing point P1 is increased, the curvature of the cable 30 when the liquid level sensor 20 floats up increases, and the load on the cable 30 can be reduced.

In addition, for example, by reducing the distance between the tip 21 of the liquid level sensor 20 and the fixed point P1, the curvature of the cable 30 when the liquid level sensor 20 floats up is reduced, and the space required for the liquid level sensor 20 to float up can be reduced. This increases the degree of freedom in the mounting symmetry of the liquid level detection unit 1A.

By connecting the mounting plate 11A to the support plate 12A, it is possible to prevent foreign matter flowing in from the grating 122 from directly adhering to the liquid level sensor 20, and also to reliably prevent the liquid level sensor 20 from being unintentionally shaken by the flowing in water, resulting in the liquid level sensor 20 falsely detecting that the warning liquid level K1 has been reached.

＜Other＞
For example, the plate unit 10A is attached to the grating 122 via the mounting plate 11A, but the mounting plate 11A does not have to be provided. In this case, the support plate 12A can be attached to the grating 122 via a metal angle member 13A.

For example, the support plate 12A may have a pair of protruding plates 16A. FIG. 7 is a perspective view of a liquid level detection unit 1B according to a modified example. The pair of protruding plates 16A protrude along each edge (long side) extending in the longitudinal direction toward the side where the liquid level sensor 20 is supported. The protruding plates 16A are provided facing each other on each long side. The protruding plates 16A are spaced apart from each other in the short direction so as to only allow the liquid level sensor 20 to float in the direction away from the support plate 12A. The protruding plate 16A is attached to the side of the short side opposite the mounting plate 11A. The liquid level sensor 20 is located between the pair of protruding plates 16A.

The liquid level sensor 20 floats on the liquid level WL between a pair of protruding plates 16A in a direction away from the support plate 12A and tilts so that the axis x1 of the liquid level sensor 20 approaches a horizontal state, thereby detecting that the liquid level WL has reached the warning liquid level K1. In other words, when the liquid level sensor 20 detects the warning liquid level K1, the liquid level sensor 20 floats on the liquid level WL and the tip 21 of the liquid level sensor 20 approaches the base end 22 in the hanging direction H, shortening the distance between the tip 21 and the base end 22. In the liquid level detection unit 1B, the warning liquid level K1 is preferably set between a pair of protruding plates 16A in the hanging direction H.

(Relationship between plate unit and liquid level sensor)
8 is a diagram for explaining the dimensions of the plate unit 10B and the liquid level sensor 20. The distance d1 between the pair of protruding plates 16A is smaller than the length 20L of the liquid level sensor 20 (d1<20L). The distance d1 is slightly larger than the maximum diameter 20Rmax of the liquid level sensor 20 (d1>20Rmax). For example, the distance d1 is preferably 1.10 to 1.30 times the maximum diameter 20Rmax. The distance d1 between the pair of protruding plates 16A is only slightly larger than the maximum diameter 20Rmax of the liquid level sensor 20.

The liquid level detection unit 1B described above has at least the same effect as the liquid level detection unit 1A. Furthermore, the direction in which the liquid level sensor 20 floats between the pair of protruding plates 16A can be uniquely restricted. This allows for greater freedom in mounting the liquid level detection unit 1B.

The liquid level sensor 20 has a circular cross-sectional shape, so even if the liquid level sensor 20 comes into contact with the protruding plate 16A, the contact is a point contact, and movement away from the support plate 12A is not impeded.

Second Embodiment
A liquid-level detection unit 1C according to the second embodiment will be described below. Fig. 9 is a perspective view of the liquid-level detection unit 1C according to the second embodiment. The power supply device 40 is not shown. Below, the following mainly describes the parts that differ from the liquid-level detection unit 1A, and the same parts as those in the liquid-level detection unit 1A are denoted by the same reference numerals and will not be described.

The liquid level detection unit 1C includes a plate unit 10C, an extension support plate (extension support portion) 13C, a liquid level sensor 20, a liquid level sensor (second liquid level sensor) 50, a cable 30, a cable (another cable) 60, and a power supply unit 40.

The extension support plate 13C is a plate member that is rectangular in front view and is made of synthetic resin or metal. The extension support plate 13C is attached to the support plate 12A via two metal plates 14C. The extension support plate 13C is connected to the support plate 12A by butting one short side against the short side of the support plate 12A on the opposite side (lower side in the hanging direction H) from the mounting plate 11A. The extension support plate 13C extends vertically relative to the grating 122. The support plate 12A supports the liquid level sensor 20 via the cable 30. The extension support plate 13C has multiple pairs of insertion holes (not shown) along the longitudinal direction. The multiple pairs of insertion holes are provided at predetermined intervals along the longitudinal direction and serve as fixed positions for the cable 60. The liquid level sensor 50 is supported on the extension support plate 13C by a belt-shaped fastener 61 on the cable 60 so that it can float.

The liquid level sensor 50 is a float type sensor. The liquid level sensor 50 is suspended from the extended support plate 13C by a cable 60. The liquid level sensor 50 is supported on the extended support plate 13C by fixing the cable 60 to the extended support plate 13C. As the liquid level rises, the liquid level sensor 50 detects that the liquid level has reached a liquid level K2 below the warning liquid level K1 by tilting one end 51 to which the cable 60 is connected in the suspension direction H so as to approach the other end 52 on the opposite side to the cable 60. The liquid level sensor 50 has the same configuration as the liquid level sensor 20.

Figure 10 is a side view of the liquid-level detection unit 1C. The cable 60 that suspends the liquid-level sensor 50 is fixed to the extended support plate 13C. The cable 60 is electrically connected to the liquid-level sensor 50. The cable 60 extends from the support plate 12A side along the extended support plate 13C. One end of the cable 60 is connected to the tip 51 side of the liquid-level sensor 50. The other end of the cable 60 is connected to the power supply unit 40 provided behind the support plate 12A.

When suspended along the extended support plate 13C, a cable 60 is attached from above in the suspension direction H along the longitudinal direction of the support plate 12A. The liquid level sensor 50 is switched on when the axis x2 extending from the tip 51 through the center of the base end (other end) 52 on the opposite side to the tip 51 in the suspension direction H approaches a horizontal state, for example.

The cable 60 extends along the extension support plate 13C. The cable 60 is attached to the extension support plate 13C with a belt-shaped fastener 61 at a position spaced a predetermined distance from the liquid level sensor 50. For example, the cable 60 is fixed to the extension support plate 13C by inserting one end of the fastener 61 through one of a pair of insertion holes in the extension support plate 13C and leading it out through the other insertion hole.

The cable 60 is supported so that it can move around the fixed point P2, which is fixed by the fastener 61, in a direction away from the extension support plate 13C. The cable 60 is movable in the area between the fixed point P2 and the tip 51 of the liquid level sensor 50. The position of the fixed point P2 may be set, for example, so that the axis x2 of the liquid level sensor 50 can be horizontal.

The liquid level sensor 50 is partially in contact with the extension support plate 13C while being suspended from the extension support plate 13C via the cable 60. When the liquid level sensor 50 is attached to the extension support plate 13C, the axis x2 extending from one end 51 along the other end 52 of the liquid level sensor 50 intersects with the extension direction of the cable 60. The axis x2 of the liquid level sensor 50 also intersects with the extension support plate 13C. The liquid level sensor 50 is supported by the extension support plate 13C such that the axis x2 is away from the extension support plate 13C on the base end 52 side with respect to the tip 51.

[Operation of the liquid level detection unit]
11 is a diagram for explaining the operation of the liquid level detection unit 1C, in which (a) is a diagram showing the initial state of the liquid level sensor 50, and (b) is a diagram showing a state in which the liquid level sensor 50 is floating on the liquid level WL and the liquid level sensor 50 is tilted to detect the liquid level K2. The liquid level K2 of the liquid level detected by the liquid level sensor 50 is arbitrarily set at a position with a predetermined distance from the grating 122 of the drainage equipment along the hanging direction H of the liquid level sensor 20, 50. The liquid level K2 is set at a position lower than the warning liquid level K1. The liquid level K2 of the liquid level detected by the liquid level sensor 50 is arbitrarily set at a position with a predetermined distance from the grating 122 along the hanging direction H of the liquid level sensor 50. The liquid level K2 is set at a position lower than the warning liquid level K1.

When the amount of rain flowing in through the grating 122 increases and the liquid level WL reaches the base end of the liquid level sensor 50, the liquid level sensor 50 begins to float up. The liquid level sensor 50 tilts together with the cable 60 and floats up away from the extended support plate 13C. As the liquid level WL rises, the tip 51 of the liquid level sensor 50 tilts, and in the hanging direction H, the tip 51 of the liquid level sensor 50 approaches the base end 52, and the axis x2 approaches horizontal or approximately horizontal.

When the liquid level WL reaches the liquid level K2 and the liquid level sensor 50 tilts and rises, for example when the axis x2 of the liquid level sensor 50 exceeds a predetermined angle with respect to the extended support plate 13C, the internal sphere rolls and the microswitch turns on. The liquid level sensor 50 sends a signal to an external device to notify that the liquid level WL in the drainage equipment is approaching the warning liquid level K1 (having reached the predetermined liquid level K2). When the liquid level WL rises further and reaches the warning liquid level K1, the liquid level sensor 20 is activated. The operation of the liquid level sensor 20 is the same as in the first embodiment.

The liquid level detection unit 1C as described above provides at least the same effect as the liquid level detection unit 1A. Furthermore, the liquid level sensor 50 can detect the liquid levels K1 and K2 at two different height positions in the drainage equipment in the hanging direction H of the liquid level detection unit 1C. For example, it can detect that the liquid level WL is rising when the liquid level WL in the drainage equipment reaches a liquid level K2 that is lower than the warning level K1 before the warning level K1 is reached. This makes it possible to recognize at an early stage that there is an increasing risk of water overflowing from the drainage equipment before the liquid level WL reaches the warning level K1.

The liquid level detection unit 1C may also have two pairs of protruding plates 16A. The pair of protruding plates 16A are provided on the support plate 12A and the extended support plate 13C, respectively.

Third Embodiment
A liquid-level detection unit 1D according to a third embodiment of the present invention will be described below. Figure 12(a) is a perspective view for explaining the configuration of a rainwater bucket 100 to which the liquid-level detection unit 1D according to the third embodiment is attached, and Figure 12(b) is a cross-sectional view taken along line b-b in (a). Below, the following mainly describes the parts that differ from the liquid-level detection unit 1A, and the same parts as those in the liquid-level detection unit 1A are given the same reference numerals and will not be described again.

The liquid level detection unit 1D according to the third embodiment is attached to, for example, a drainage facility (hereinafter also referred to as a "rainwater manhole") 100 that drains rainwater into a sewer pipe. When water exceeding the allowable amount overflows from the sewer pipe and rises up inside the rainwater manhole, the liquid level detection unit 1D detects that the liquid level in the rainwater manhole has reached a predetermined liquid level (hereinafter also referred to as a "warning liquid level") K1. The liquid level detection unit 1D is applied, for example, to known drainage facilities, and the drainage facilities to which it is applied are not limited to specific drainage facilities. For example, the liquid level detection unit 1D according to the embodiment of the present invention is applied to the rainwater manhole 100 shown in FIG. 12.

The rainwater manhole 100 collects rainwater on the grounds of a building such as a house. The rainwater manhole 100 is made of concrete, for example. The rainwater manhole 100 is buried underground and allows water that flows into it to flow into, for example, a sewer pipe.

The rainwater manhole 100 has a main body 110 and an inlet 120. The main body 110 and the inlet 120 are formed integrally with each other. The main body 110 is buried in the ground. The main body 110 is formed in a cylindrical shape. The main body 110 has a pipe opening 111. For example, a sewer pipe is connected to the pipe opening 111, and water that flows into the rainwater manhole 100 is discharged into the sewer pipe.

The inlet 120 is provided at one end in the axial direction of the main body 110. When the rainwater manhole 100 is installed underground, the inlet 120 is exposed to the ground. The inlet 120 has an inlet opening 121. For example, rainwater flows into the main body 110 through the inlet opening 121. The inlet opening 121 is closed by a lattice-shaped cover such as a grating 122.

The rainwater basin 100 is provided with a liquid level detection unit 1D that detects and measures the liquid level in the rainwater basin 100. The liquid level detection unit 1D according to the third embodiment is formed in a cylindrical shape with one end closed and the other end open, and has a short axis Sa and a long axis La in a cross section perpendicular to the extension direction, and includes a cylindrical member (hereinafter also referred to as a "cover") 10D having a pair of short axis side wall portions 12D, 13D opposed in the direction of the short axis Sa and a pair of long axis side wall portions 14D, 15D opposed in the direction of the long axis La, and a float-type liquid level sensor 20 that is suspended from one end of the cylindrical member 10D to the other end via a cable 30 and is housed within the cylindrical member 10D and detects when the liquid level reaches a predetermined liquid level. The cable 30 that suspends the liquid level sensor 20 is attached to one of the pair of long axis side walls 14D, 15D, and the axis x1 that extends from one end of the liquid level sensor 20 to which the cable 30 is connected along the other end opposite the cable 30 is inclined from one of the long axis side walls 14D, 15D toward the other of the long axis side walls 14D, 15D. The configuration of the liquid level detection unit 1D will be described in detail below.

[Liquid level detection unit]
13 is a see-through perspective view of a liquid level detection unit 1D according to a third embodiment of the present invention. The liquid level detection unit 1D is attached to the grating 122 of the rainwater tank 100 from the side of the main body 110. The liquid level detection unit 1D is attached to the grating 122 of the rainwater tank 100 via a stainless steel fastener 101. The liquid level detection unit 1D includes a cover 10D, a liquid level sensor 20, a cable 30, and a power supply unit 40.

(cover)
14A and 14B are perspective views of the cover 10D, where (a) is a perspective view of the cover 10D seen from above, and (b) is a perspective view of the cover 10D seen from below. The cover 10D is a cylindrical member with one end closed and the other end open. The cover 10D is, for example, an integrally molded member made of synthetic resin. The cover 10D is a cylindrical member with an elliptical or substantially elliptical cross-sectional shape intersecting the extension direction.

Figure 15 is a plan view of the cover 10D. The cover 10D has a short axis Sa in cross section and a long axis La that is longer than the short axis Sa. The cover 10D has an upper end wall portion 11D, a pair of short axis side walls 12D, 13D, and a pair of long axis side walls 14D, 15D. The cover 10D defines an accommodation space S that accommodates the liquid level sensor 20 by the upper end wall portion 11D, the short axis side walls 12D, 13D, and the long axis side walls 14D, 15D. The pair of short axis side walls 12D, 13D face each other in the direction of the short axis Sa and extend along the direction of the long axis La. The long axis side walls 14D, 15D face each other in the direction of the long axis La and extend along the direction of the short axis Sa.

The upper end wall portion 11D closes one end of the cover 10D. The liquid level detection unit 1D is attached to the grating 122 at the upper end wall portion 11D. At the upper end wall portion 11D, the cover 10D has a short rib (first rib) 11Da that protrudes along the short axis side wall portions 12D, 13D to the side opposite the other end, and a long rib (second rib) 11Db that protrudes along the long axis side wall portions 14D, 15D to the side opposite the other end. The first rib 11Da and the second rib 11Db can support a fastener 101 that fastens the cover 10D to the drainage equipment 100.

The short ribs 11Da and the long ribs 11Db are formed in a thin plate shape. The number of short ribs 11Da and long ribs 11Db is not particularly limited. Each short rib 11Da extends along the short axis Sa. The short ribs 11Da are each provided at equal intervals in the direction of the long axis La. The short ribs 11Da protrude from the upper end wall portion 11D to the side opposite the storage space S.

The longitudinal ribs 11Db extend along the long axis La so as to intersect with the short ribs 11Da. The longitudinal ribs 11Db extend between the short ribs 11Da provided at both ends in the long axis La direction. The longitudinal ribs 11Db are each provided at equal intervals between one end and the other end of the short rib 11Da in the short axis Sa direction.

The height of the short rib 11Da and the long rib 11Db is greater than the thickness of the cable 30 attached to the upper end wall portion 11D. This makes it possible to prevent the cable 30 from coming into contact with the grating 122 when the liquid level detection unit 1D is attached to the grating 122.

The short ribs 11Da and the long ribs 11Db each have a support opening (not shown) that supports the stainless steel binding device 101. The support opening in each short rib 11Da is formed through the short rib 11Da in the thickness direction. The support opening in the short rib 11Da is provided between the intersections of the short ribs 11Da and the long ribs 11Db.

The support openings in each longitudinal rib 11Db are formed through the longitudinal rib 11Db in the thickness direction. The support openings are provided between the intersections of the short ribs 11Da and the longitudinal ribs 11Db.

Depending on the lattice pattern of the grating 122 to which the liquid level detection unit 1D is attached, or depending on the position of the grating 122 to which the liquid level detection unit 1D is attached, the binding device 101 can be attached by selecting a support opening at an appropriate position. Note that there is no particular limit to the number of short ribs 11Da, long ribs 11Db, and support openings.

A guide portion 11Dc is formed on the upper end wall portion 11D to guide the cable 30 that suspends the liquid level sensor 20. The guide portion 11Dc is provided on the side of the long axis side wall portion 14D in the direction of the long axis La. The guide portion 11Dc guides the cable 30 from the outside of the cover 10D into the storage space S. The cable 30 is attached to the guide portion 11Dc.

The pair of short-axis side walls 12D, 13D extend linearly along the long axis La. The short-axis side walls 12D, 13D are spaced apart from each other at a predetermined distance d2 in the direction of the short axis Sa. The distance d2 between the short-axis side walls 12D, 13D is set to a degree that does not allow the liquid level sensor 20 to float in the direction of the short axis Sa.

At least one hole 16D is formed in the cover 10D. The short-axis side walls 12D and 13D each have a plurality of holes 16D. In the extension direction of the cover 10D, the hole 16D is provided on the upper end wall 11D side of the liquid level sensor 20 when the liquid level sensor 20 is suspended. Water and air inside the cover 10D are discharged to the outside of the cover 10D through the hole 16D.

The pair of long axis side walls 14D, 15D extend between the ends of the pair of short axis side walls 12D, 13D in the direction of the long axis La. The long axis side walls 14D, 15D extend in a convex arc shape from the storage space S to the outside in a plan view.

The pair of long axis side walls 14D, 15D are spaced apart from each other at a predetermined distance d3 in the direction of the long axis La. The distance d3 between each of the long axis side walls 14D, 15D is set to allow the liquid level sensor 20 to float in the direction of the long axis La in response to a rise in the liquid level, and to tilt to an extent that at least allows the liquid level sensor 20 to detect that the liquid level has reached the warning liquid level K1.

(Liquid level sensor and cable)
The liquid level sensor 20 is a float type sensor. The liquid level sensor 20 is housed in a state of being suspended within the cover 10D by a cable 30. The liquid level sensor 20 floats on the liquid surface within the cover 10D, and as the liquid level within the cover 10D rises, the liquid level sensor 20 floats up along the long axis side walls 14D, 15D of the cover 10D, and detects the warning liquid level K1 when one end 21 to which the cable 30 is connected approaches the other end 22 opposite the cable 30 in the suspension direction H.

When the liquid level sensor 20 is suspended within the cover 10D, in the hanging direction H along the longitudinal direction of the cover 10D, a cable 30 is attached to one end (tip) 21 of the liquid level sensor 20 on the side of the upper end wall portion 11D. The liquid level sensor 20 is switched on when the axis x1 extending from the tip 21 through the center of the base end (other end) 22 on the opposite side to the tip 21 in the hanging direction H approaches a horizontal state, for example.

When the liquid level sensor 20 is housed in the cover 10D, its base end 22 is located closer to the upper end wall portion 11D than the other end of the cover 10D opposite the upper end wall portion 11D. In other words, the entire liquid level sensor 20 is located within the housing space S.

Figure 16 is a cross-sectional view showing the liquid level sensor 20 attached to the cover 10D. The cable 30 that suspends the liquid level sensor 20 is attached to one of the pair of long axis side walls 14D, 15D, i.e., the long axis side wall 14D.

The cable 30 is electrically connected to the liquid level sensor 20. The cable 30 extends from the outside to the inside of the cover 10D through the guide portion 11Dc of the upper end wall portion 11D. One end of the cable 30 is connected to the tip 21 side of the liquid level sensor 20. The other end of the cable 30 is connected to a power supply unit 40 provided outside the cover 10D.

The cable 30 extends along one of the long axis side walls 14D. The cable 30 is attached to one of the long axis side walls 14D with a band-shaped fastener 31 at a position spaced a predetermined distance from the liquid level sensor 20. For example, two insertion holes (not shown) are formed in the long axis side wall 14D, and the cable 30 is fixed to the cover 10D by inserting one end of the fastener 31 into the cover 10D from one of the insertion holes, passing through the long axis side wall 15D side of the cable 30, and then leading it out of the cover 10D from the other insertion hole.

The cable 30 is supported so that it can move around the fixed point P1, which is fixed by the fastener 31, toward the long axis side wall portion 15D. The cable 30 is movable along the long axis La in the area between the fixed point P1 and the tip 21 of the liquid level sensor 20. The position of the fixed point P1 may be set, for example, so that the liquid level sensor 20 allows the axis x1 of the liquid level sensor 20 to be horizontal.

When the liquid level sensor 20 is suspended from the cover 10D via the cable 30, a portion of the outer circumferential surface is in contact with the long axis side wall portion 14D. When the liquid level sensor 20 is attached to the cover 10D, the axis x1 extending from one end 21 along the other end 22 of the liquid level sensor 20 is inclined from the long axis side wall portion 14D toward the long axis side wall portion 15D. On the base end 22 side, the axis x1 of the liquid level sensor 20 is away from the long axis side wall portion 14D relative to the tip 21 and is close to the long axis side wall portion 15D.

(Relationship between cover and liquid level sensor)
17 is a diagram for explaining the dimensions of the cover 10D and the liquid level sensor 20. The distance d2 between the pair of minor axis side walls 12D, 13D is smaller than the length 20L of the liquid level sensor 20 (d2<20L). The distance d2 is slightly larger than the maximum diameter 20Rmax of the liquid level sensor 20 (d2>20Rmax). For example, the distance d2 is preferably 1.10 to 1.30 times the maximum diameter 20Rmax. The distance d2 may be set so as to prevent the liquid level sensor 20 from floating up along the direction of the minor axis Sa.

The distance d3 between the pair of long axis side walls 14D, 15D is greater than the length 20L of the liquid level sensor 20 (d3>20L). The distance d3 is greater than at least the length 20L of the liquid level sensor 20 plus the distance 30L from the fixed point P1 of the cable 30 to the tip 21 of the liquid level sensor 20 when the liquid level sensor 20 is floating and tilted horizontally (d3>20L+30L). The distance d3 should be set so as not to hinder the floating of the liquid level sensor 20 along the long axis La and the detection of the warning liquid level K1 at least in the process of the axis x1 approaching a horizontal state.

(Power supply)
The power supply device 40 is attached to the grating 122. A cable 30 is electrically connected to the power supply device 40. The power supply device 40 supplies electricity to the liquid level sensor 20 via the cable 30. The power supply device 40 has a plurality of hooks 41. The power supply device 40 is attached to the grating 122 by passing the fasteners 101 through the hooks 41.

[Operation of the liquid level detection unit]
18 is a cross-sectional view showing a state in which the liquid-level detection unit 1D is attached to the grating 122. The liquid-level sensor 20 floats on the liquid level WL along the minor-axis sidewall portions 12D, 13D in the direction of the major axis La and tilts so that the axis x1 of the liquid-level sensor 20 approaches a horizontal state, thereby detecting that the liquid level WL has reached the warning liquid level K1. In other words, when the liquid-level sensor 20 detects the warning liquid level K1, the liquid-level sensor 20 floats on the liquid level WL, and the tip 21 of the liquid-level sensor 20 approaches the base end 22 in the hanging direction H, and the distance between the tip 21 and the base end 22 becomes shorter.

The warning level K1 of the liquid level WL detected by the liquid level sensor 20 is set arbitrarily at a position spaced a predetermined distance h from the grating 122 of the rainwater manhole 100 along the hanging direction H of the liquid level sensor 20. When the liquid level WL reaches the warning level K1, it is an indication that there is a risk of water overflowing from the rainwater manhole 100, for example. For example, the liquid level sensor 20 is configured to detect the liquid level at a predetermined height from the base end 22. By adjusting the length of the cable 30 within the cover 10D, the hanging position of the liquid level sensor 20 can be changed as appropriate to correspond to the arbitrarily set warning level K1.

Figure 19 is a diagram for explaining the operation of the liquid level detection unit 1D, where (a) is a diagram showing the initial state of the liquid level sensor 20, (b) is a diagram showing the state in which the liquid level sensor 20 is tilted while floating on the liquid level WL, before detecting the warning liquid level K1, and (c) is a diagram showing the state in which the liquid level WL further rises and the liquid level sensor 20 tilts to detect the warning liquid level K1. For example, heavy rain can cause an unexpected amount of rainwater to flow into the rainwater manhole 100 through the grating 122, more than can be discharged into the sewer pipe. Water overflowing from the pipe opening 111 returns into the rainwater manhole 100. As a result, the liquid level WL in the main body 110 of the rainwater manhole 100 rises (see Figure 19 (a)).

As the level of rainwater flowing into the rainwater tank 100 rises, water also enters the inside of the cover 10D from the side opposite the upper end wall portion 11D. When the liquid level WL reaches the base end 22 of the liquid level sensor 20, the liquid level sensor 20 begins to float.

The distance d2 between the short axis sidewalls 12D, 13D of the cover 10D is only slightly larger than the maximum diameter 20Rmax of the liquid level sensor 20. The liquid level sensor 20 rises toward the long axis sidewall 15D along the long axis La while tilting together with the cable 30 along the short axis sidewalls 12D, 13D, rather than along the short axis Sa and vertical direction (hanging direction H) (see FIG. 19(b)).

The mass of the liquid level sensor 20 is greater than the buoyancy. In the liquid level sensor 20, the center of buoyancy is on the base end 22 side, and the center of gravity of the liquid level sensor 20 is located on the tip end 21 side. Therefore, due to the misalignment between the center of buoyancy and the center of gravity, a rotational moment is generated in the liquid level sensor 20. Due to the generation of the rotational moment, as the liquid level WL rises, the tip 21 of the liquid level sensor 20 tilts, and in the hanging direction H, the tip 21 of the liquid level sensor 20 approaches the base end 22 side, and the axis x1 approaches horizontal or approximately horizontal (see Figure 19 (c)).

When the liquid level WL reaches the warning level K1, for example, when the axis x1 of the liquid level sensor 20 exceeds a predetermined angle with the long axis side wall portion 14D, the internal sphere rolls and the microswitch turns on. The liquid level sensor 20 sends a signal to an external device to warn that the liquid level WL in the rainwater manhole 100 has reached the warning level K1.

By attaching the above-described liquid level detection unit 1D to the drainage equipment 100, it is possible to recognize the occurrence of flood damage in advance. According to the liquid level detection unit 1D, the liquid level sensor 20 is housed within the cover 10D, which prevents foreign matter flowing in from the grating 122 from adhering to the liquid level sensor 20 and reliably prevents the liquid level sensor 20 from being unintentionally shaken by the flowing in water, resulting in the liquid level sensor 20 falsely detecting that the warning liquid level K1 has been reached. The cover 10D allows the liquid level sensor 20 to detect the warning liquid level K1 based solely on the liquid level WL rising within the cover 10D.

The distance d2 between the minor axis side wall portions 12D, 13D is set so that the cover 10D allows the liquid level sensor 20 to float only along the major axis La. In other words, the cover 10D limits the direction in which the liquid level sensor 20 floats to only the direction along the major axis La. The cover 10D does not need to provide space to allow the liquid level sensor 20 to float in the direction along the minor axis Sa, and the cover 10D can be made smaller in size in the direction of the minor axis Sa. This reduces the cost of parts and the manufacturing cost of the cover 10D. Furthermore, the smaller cover 10D allows greater freedom in the location in which the liquid level detection unit 1D is installed.

Since the liquid level sensor 20 is attached to one of the long axis side walls 14D, the direction in which the liquid level sensor 20 floats can be limited to only one direction (the direction toward the other long axis side wall 15D). This is superior in terms of making the cover 10D smaller than a configuration in which the liquid level sensor 20 is installed at the midpoint of the distance d3 between a pair of long axis side walls 14D, 15D and the liquid level sensor 20 can float in both directions.

The liquid level sensor 20 is suspended with the base end 22 tilted toward the long axis side wall portion 15D, which makes it easier for the liquid level sensor 20 to float up along the long axis La.

The liquid level sensor 20 has a circular cross-sectional shape, so even if the liquid level sensor 20 comes into contact with the minor axis side wall portions 12D and 13D, the contact is a point contact, and movement in the direction of the major axis La is not hindered.

The holes 16D are provided in the short-axis side walls 12D and 13D, so that air that has entered the cover 10D can be discharged to the outside of the cover 10D, preventing air from accumulating inside the cover 10D and causing the liquid level inside the cover 10D to drop unintentionally.

In addition, multiple ribs 11Da, 11Db extend in a lattice pattern along the direction of the minor axis Sa and the direction of the major axis La on the upper end wall portion 11D of the cover 10D. This increases the freedom of position and orientation of the liquid level detection unit 1D to be attached via the fastener 101 in accordance with the object to which the liquid level detection unit 1D is attached, for example, the lattice shape of the grating 122.

＜Other＞
For example, in the liquid-level detection unit 1D of the above embodiment, the liquid-level sensor 20 is provided on one of the major axis side walls 14D. Alternatively, the cable 30 may be fixed to either of the minor axis side walls 12D or 13D by a fastener 31 at a middle position in the direction of the major axis La. In this case, the cover 10D is designed to have a distance d3 that allows the liquid-level sensor 20 to float in both directions in the direction of the major axis La.

In addition, the cross-sectional shape of the cover 10D intersecting the extension direction is elliptical or approximately elliptical, but it may be rectangular or approximately rectangular. In addition, the cover 10D may be formed from a metal mesh cage or the like, as long as the cross-sectional shape intersecting the extension direction is the same.

<Fourth embodiment>
A liquid-level detection unit 1E according to the fourth embodiment will be described below. Fig. 20 is a diagram for explaining the configuration of the liquid-level detection unit 1E according to the fourth embodiment, where (a) is a perspective view and (b) is a front view. Note that the power supply device 40 is not shown. Below, the following mainly describes the parts that differ from the liquid-level detection unit 1D, and the same parts as the liquid-level detection unit 1D are denoted by the same reference numerals and will not be described.

The liquid level detection unit 1E according to the fourth embodiment is applied to, for example, a rainwater manhole 100 similar to the liquid level detection unit 1D. The liquid level detection unit 1E is suspended below the liquid level sensor 20 from one end of the cover 10E to the other end via a cable 60 separate from the cable 30 and is housed within the cover 10E, and further includes a float-type second liquid level sensor 50 that detects when the liquid reaches another predetermined liquid level K2 below the warning liquid level K1 detected by the liquid level sensor 20.

The liquid level detection unit 1E includes a cover 10E, liquid level sensors 20 and 50, cables 30 and 60, and a power supply (not shown). The cover 10E has the same configuration as the cover 10D of the third embodiment.

A guide portion 11Ed is formed on the upper end wall portion 11D to guide the cable 60 that suspends the liquid level sensor 50. The guide portion 11Ed is provided on the side of the long axis side wall portion 15D opposite the long axis side wall portion 14D in the direction of the long axis La. The guide portion 11Ed guides the cable 60 from the outside of the cover 10E into the storage space S. The cable 60 is attached to the guide portion 11Ed.

A guide path 17E is formed in the long axis side wall portion 15D at a position that does not contact the liquid level sensor 20 in a raised state, and guides the cable 60. The long axis side wall portion 15D has a guide path 17E that extends along the extension direction of the cover 10E. The guide path 17E extends over an area that faces the liquid level sensor 20. The cable 60, which is guided into the cover 10E through the guide portion 11Ed of the upper end wall portion 11D, is passed through the guide path 17E.

21(a) is a cross-sectional view taken along line XXI(a)-XXI(a) in FIG. 20(b), showing the liquid level sensor 20 in a raised state, and FIG. 21(b) is a cross-sectional view taken along line XXI(b)-XXI(b) in FIG. 20(b), showing the liquid level sensor 50 in a raised state. The guide path 17E is formed in the center of the long axis side wall 15D in the direction of the short axis Sa. The guide path 17E is a portion where the gap of the cover 10E is narrowed in the direction of the short axis Sa. The gap d4 from the long axis side wall 14D to the guide path 17E is set to be at least greater than the sum of the length 20L of the liquid level sensor 20 and the gap 30L of the cable 30 (20L+30L) (d4>20L+30L).

A stopper 18E is provided on the cover 10E. The stopper 18E is provided between the liquid level sensor 20 and the liquid level sensor 50 in the hanging direction H. The stopper 18E prevents the liquid level sensor 50 from floating up toward the liquid level sensor 20 relative to the position corresponding to the liquid level K2.

The stopper 18E is a member formed separately from the cover 10E, and is attached to at least one of the short-axis side wall portions 12D, 13D and the long-axis side wall portions 14D, 15D. The stopper 18E prevents the liquid level sensor 50, which is located below the liquid level sensor 20, from floating up toward the liquid level sensor 20 as the liquid level rises, and prevents the movement of the liquid level sensor 20 along the long axis La.

The stopper 18E is provided between the liquid level sensor 20 and the second liquid level sensor 50 in the hanging direction H. Specifically, the stopper 18E is provided on the cover 10E above the liquid level K2 that the second liquid level sensor 50 detects in the hanging direction H and below the lower end of the movable range of the liquid level sensor 20. The stopper 18E is also provided on the liquid level sensor 20 side (above) of the fixed point P2 at which the cable 60 is fixed to the long axis side wall portion 15D by the fastener 61.

The configuration of the liquid level sensor 50 is the same as that of the liquid level sensor 20. The configuration of the cable 60 is the same as that of the cable 30. The liquid level sensor 50 is housed in a state in which it is suspended by the cable 60 within the cover 10E. The liquid level sensor 50 is located lower than the liquid level sensor 20 in the suspension direction H. As the liquid level within the cover 10E rises while floating on the liquid surface within the cover 10E, one end 51 to which the cable 60 is connected approaches the other end 52 of the liquid level sensor 50 in the suspension direction H, causing the liquid level sensor 50 to float up along the long axis side walls 14D, 15D of the cover 10E and detect the predetermined liquid level K2.

When the liquid level sensor 50 is housed in the cover 10E, its base end 52 is located closer to the upper end wall portion 11D than the other end of the cover 10E opposite the upper end wall portion 11D. In other words, the entire liquid level sensor 50 is located within the housing space S.

The cable 60 extends from the outside to the inside of the cover 10E through the guide portion 11Ed of the upper end wall portion 11D. The cable 30 is connected to a power supply unit 40 provided outside the cover 10E.

The cable 60 extends along one of the long axis side walls 15D. The cable 60 is attached to one of the long axis side walls 15D with a band-shaped fastener 61 at a position spaced a predetermined distance from the liquid level sensor 50. For example, two insertion holes (not shown) are formed in the long axis side wall 15D, and the cable 60 is fixed to the cover 10E by inserting one end of the fastener 61 into the cover 10E from one of the insertion holes, passing through the long axis side wall 15D side of the cable 60, and then leading it out of the cover 10E from the other insertion hole.

The cable 60 is supported so that it can move around the fixed point P2, which is fixed by the fastener 61, toward the long axis side wall portion 14D. The cable 60 is movable along the long axis La in the area between the fixed point P2 and the tip 51 of the liquid level sensor 50. The position of the fixed point P2 may be set, for example, so that the liquid level sensor 50 allows the axis x2 of the liquid level sensor 50 to be horizontal.

When the liquid level sensor 50 is hung from the cover 10E via the cable 60, a portion of the outer circumferential surface is in contact with the long axis side wall portion 15D. When the liquid level sensor 50 is attached to the cover 10E, the axis x2 extending from one end 51 along the other end 52 of the liquid level sensor 50 is inclined from the long axis side wall portion 15D toward the long axis side wall portion 14D. The axis x2 of the liquid level sensor 50 is away from the long axis side wall portion 15D relative to the tip end 51 on the base end 52 side and is close to the long axis side wall portion 14D.

The length 50L of the liquid level sensor 50 plus the distance from the fixed point P2 of the cable 60 to the tip 51 of the liquid level sensor 50 when the liquid level sensor 20 is floating and tilted horizontally (50L + 60L) is set to be smaller than the distance d3 between the pair of long axis side walls 14D, 15D.

[Operation of the liquid level detection unit]
22 is a diagram for explaining the operation of the liquid level detection unit 1E, in which (a) is a diagram showing the initial state of the liquid level sensor 50, (b) is a diagram showing a state in which the liquid level sensor 50 is floating on the liquid level WL and tilted, before detecting the liquid level K2, and (c) is a diagram showing a state in which the liquid level WL further rises and the liquid level sensor 50 is tilted and detects the liquid level K2. The liquid level K2 of the liquid level detected by the liquid level sensor 50 is arbitrarily set at a position spaced a predetermined distance from the grating 122 of the rainwater manhole 100 along the hanging direction H of the liquid level sensor 20. The liquid level K2 is set at a position lower than the warning liquid level K1.

For example, if the rainwater manhole 100 has another pipe opening (not shown) below the pipe opening 111, heavy rain may cause an unexpected amount of rainwater to flow into the rainwater manhole 100 through the grating 122, more than can be drained into the sewer pipe. Water that overflows from the other pipe opening will return into the rainwater manhole 100. This causes the liquid level WL in the main body 110 of the rainwater manhole 100 to rise (see FIG. 22(a)).

As the level of rainwater flowing into the rainwater tank 100 rises, water also enters the inside of the cover 10E from the side opposite the upper end wall portion 11D. When the liquid level WL reaches the base end of the liquid level sensor 50, the liquid level sensor 50 begins to float.

The distance d2 between the short axis sidewalls 12D, 13D of the cover 10E is only slightly larger than the maximum diameter of the liquid level sensor 50. The liquid level sensor 50 rises toward the long axis sidewall 14D along the long axis La while tilting together with the cable 60 along the short axis sidewalls 12D, 13D, rather than along the short axis Sa and vertically (see FIG. 22(b)).

The mass of the liquid level sensor 50 is greater than the buoyancy. In the liquid level sensor 50, the center of buoyancy is on the base end side, and the center of gravity of the liquid level sensor 50 is located on the tip end side. Therefore, due to the misalignment between the center of buoyancy and the center of gravity, a rotational moment is generated in the liquid level sensor 50. Due to the generation of the rotational moment, as the water surface WL rises, the tip 51 of the liquid level sensor 50 tilts, and in the hanging direction H, the tip 51 of the liquid level sensor 50 approaches the base end 52 side, and the axis x2 approaches horizontal or approximately horizontal (see Figure 12 (c)).

When the liquid level WL reaches the liquid level K2, for example, the axis x2 of the liquid level sensor 50 becomes horizontal or nearly horizontal, the internal sphere rolls, and the microswitch turns on. The liquid level sensor 50 transmits a signal to an external device to warn that the water level WL in the rainwater manhole 100 has reached the liquid level K2.

Even if the liquid level inside the cover 10E rises further, the stopper 14 restricts the liquid level sensor 50 from floating up. When the liquid level WL rises further beyond the stopper 14 and reaches the warning liquid level K1, the liquid level sensor 20 is activated. The operation of the liquid level sensor 20 is the same as in the first embodiment.

The liquid level detection unit 1A described above can detect the liquid levels K1 and K2 at two different height positions in the hanging direction H of the liquid level detection unit 1A. For example, if the rainwater manhole 100 has two pipe openings in the height direction, it can detect that water is backflowing from the lower pipe opening when the liquid level WL reaches a liquid level K2, which is lower than the warning liquid level K1, before it reaches the warning liquid level K1. This makes it possible to recognize at an early stage that there is an increasing risk of water overflowing from the rainwater manhole 100, before the liquid level WL reaches the warning liquid level K1.

Furthermore, because the cover 10A has a guide path 13c, the cable 60 of the liquid level sensor 50 does not interfere with the floating of the liquid level sensor 20.

Furthermore, cover 10A has a stopper 14, which prevents liquid level sensor 50 from floating up and interfering with the floating of liquid level sensor 20.

＜Other＞
For example, the liquid level sensor 50 was provided on the side of the long axis side wall portion 15D opposite the side of the long axis side wall portion 14D on which the liquid level sensor 20 was provided, but it may also be provided on the side of the long axis side wall portion 14D.

Although the preferred embodiments 1 to 4 of the present invention have been described above, the present invention is not limited to the above-mentioned embodiment 4, and includes all aspects included in the concept of the present invention and the scope of the claims. In addition, each configuration may be appropriately and selectively combined so as to achieve at least a part of the above-mentioned problems and effects. In addition, for example, the shape, material, arrangement, size, etc. of each component in the above-mentioned embodiments may be appropriately changed depending on the specific usage mode of the present invention.

1A, 1B, 1C, 1D, 1E...Liquid level detection unit, 10A, 10B...Plate unit, 10D...Cover (cylindrical member), 11A...Mounting plate, 11D...Upper end wall portion, 11Da...Short rib (first rib), 11Db...Long rib (second rib), 11Dc, 11Ed...Guide portion, 12A...Support plate (support portion), 12D, 13D...Short shaft side wall portion, 13C...Extended support plate (extended support portion), 14D, 15D...Long shaft side wall portion, 13A...Angle member, 14A...Through hole, 15A...Through hole, 16A...Protruding plate, 16D...Hole, 17E...Guide path, 18E...S Topper, 20... liquid level sensor, 20L... length, 20R... diameter, 20Rmax... maximum diameter, 21... tip (one end), 22... base end (other end), 30... cable, 30L... interval, 31... fastener, 40... power supply, 41... hook, 50... liquid level sensor (second liquid level sensor), 50L... length, 51... tip (one end), 52... base end (other end), 60... cable (another cable), 61... fastener, 100... drainage equipment, rainwater manhole, 101... fastener, 110... main body, 111... pipe opening, 120... inlet, 121... inlet opening, 122... grating, La... long axis, Sa... short axis

Claims (4)

A float-type liquid level sensor that is suspended via a cable inside the drainage equipment and detects when the liquid level reaches a predetermined level;
a support portion that extends in an extension direction of the cable within the drainage equipment and supports the liquid level sensor via the cable so as to be able to float;
Equipped with
When the liquid level sensor is supported by the support, an axis extending from one end to which the cable is connected to a second end opposite the cable intersects with an extension direction of the cable,
The cable is supported so as to be movable from a fixed point to a direction away from the support part, the fixed point being a center of the cable, the fixed point being a fixed point on the support part,
A liquid level detection unit for drainage equipment, characterized in that the liquid level sensor floats on the liquid surface in a direction away from the support part, tilting so that the axis approaches a horizontal state, and the distance between one end of the liquid level sensor and the other end becomes shorter . The liquid level detection unit for a drainage system according to claim 1 , characterized in that the mass of the liquid level sensor is greater than the buoyancy . The liquid level detection unit for drainage equipment according to claim 2 , characterized in that the center of buoyancy in the liquid level sensor is on the side of the other end, and the center of gravity of the liquid level sensor is on the side of the one end. The liquid level detection unit for drainage equipment according to claim 1, characterized in that it is provided with an attachment part which extends vertically from the support part to the side on which the liquid level sensor is supported at the upper end of the support part in the hanging direction of the liquid level sensor and is attached to the drainage equipment .

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