JPH039409B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a liquid used to measure the position of a liquid level in a waterway or tank, or to measure the position of a liquid level upstream of a weir in a weir-type flowmeter. Regarding the structure of the position detector. In particular, the present invention relates to a structure in which the position of the liquid level is detected by a float, and an electric signal converter such as a potentiometer, which is separated from the fluid system by a partition wall, is connected and operated by a magnetic coupling.

Prior Art The conventional liquid level detection structure has a cylindrical partition wall arranged vertically, a float slidably attached to the outside of the partition wall, and an operating rod of an electric signal converter such as a potentiometer to the inside of the partition wall. An annular magnet is fixed to the float, a cylindrical magnet is fixed to the operating rod, and they are magnetically connected across a partition wall.

The float floats on the liquid surface, is guided by a cylindrical partition wall, and is displaced up and down with the liquid level. The magnets fixed to the float and the operating rod are attracted to each other by magnetic force, and as the float is displaced, the operating rod inside the bulkhead is displaced. As a result, the position of the liquid level is extracted as an electrical signal from the electrical signal converter.

Problems to be Solved by the Invention In this case, the magnet fixed to the float and the magnet fixed to the operating rod are magnetically attracted to each other across the partition wall, and are pressed into contact with each other. Therefore, when the float is displaced up and down, sliding friction resistance acts between the float and the bulkhead and between the operating rod and the bulkhead, so the displacement resistance becomes relatively large and the displacement of the float and the operating rod lags behind the liquid level. As a result, hysteresis occurs. For this reason, accuracy is poor when detecting minute changes in liquid level. If the magnetic force of the magnet is weakened, the displacement resistance will be reduced, but the connection between the float and the operating rod will become unstable, so it cannot be made weaker than necessary.

The technical problem of the present invention is to reduce the displacement resistance without weakening the magnetic force of the magnet of the magnetic joint.

Means for Solving the Problems The technical means of the present invention taken to solve the above-mentioned technical problems is to move the float to the outside of the cylindrical partition wall so that it can be freely displaced in the axial direction and freely rotated in the circumferential direction. The float and the operating rod of the electric signal converter are connected by a magnetic joint across a partition wall, and the embankment has an inlet for inflowing liquid at one end and an opening for allowing inflowing liquid to flow in the tangential direction of the float at the other end. parts,
A partition wall, which is provided above the float and whose upper end is located below the upper end of the bank member, is provided in the middle of the bank member to form a reservoir for the inflow liquid at one end of the bank member, and one end is placed inside the reservoir and another partition wall is provided in the middle of the bank member. Arrange an inverted U-shaped tube whose end opens into the liquid surrounding the float and whose uppermost part is located below the upper end of the partition wall, and the other end of the inverted U-shaped tube opens in the tangential direction of the float. This is a U-shaped tube with a small hole at the top of the downward slope.

Effects The effects of the above technical means are as follows.
The inflowing liquid first collects in the reservoir portion of the bank member. Air is replaced through the pores provided at the top of the inverted U-shaped tube, so the internal pressure of the inverted U-shaped tube remains constant regardless of the liquid level around the float. Once the liquid level reaches a certain level, it is intermittently introduced into the liquid around the float through the inverted U-shaped tube. If the amount of inflow is large, it is continuously introduced through the inverted U-shaped pipe. If the amount of inflow is large, in addition to this, the water will flow down from the embankment member to the surroundings of the float. The inverted U-shaped tube allows the inflowing fluid to flow in the tangential direction of the float, causing the fluid around the float to rotate.
The float rotates indirectly due to the action of viscosity. When the amount of inflow increases and it also flows from the bank members,
Since the amount of liquid around the float is increasing, it becomes difficult to rotate the surrounding liquid only by the rotational action of the inverted U-shaped tube. At this time, the inflow fluid flowing in the tangential direction of the float from the bank member also rotates the liquid around the float, so that the rotation of the float is reliably maintained.

The float then rolls on the outer peripheral surface of the cylindrical partition wall while maintaining magnetic coupling with the operating rod. Rolling frictional resistance acts between the float, the bulkhead, and the operating rod, the displacement resistance between the float and the operating rod is small, and the magnetic coupling between them is as strong and stable as before.

Therefore, the float and the operating rod are displaced to closely follow minute changes in the liquid level, hysteresis is reduced, and liquid level detection accuracy is improved.

Effect of the invention The present invention produces the following unique effects.

Since rolling frictional resistance is extremely small compared to sliding frictional resistance, the liquid level detection structure of the present invention has a liquid level detection accuracy that is one order of magnitude better than that of the conventional example.

Since the float of the present invention displaces up and down while rolling around the partition wall, even if foreign matter such as scale adheres to the outer surface of the partition wall, the float is unlikely to be prevented from moving.

The structure is simpler and less prone to failure than using ball bearings to reduce displacement resistance.

Even if the inflowing liquid is minute, a predetermined amount of liquid flows in the tangential direction of the float through the inverted U-shaped tube,
Furthermore, if the amount of inflow increases, in addition to this, the liquid is caused to flow in from the bank member in the tangential direction of the float, causing the liquid around the float to rotate, so that the float can be rotated reliably.

Since the float is indirectly rotated by the action of viscosity caused by the rotation of the liquid around the float, the liquid continues to rotate by inertia, and even if the amount of inflowing fluid is minute, the rotation of the float is maintained. A device that uses the power of an electric motor or pump to rotate the float or surrounding liquid is expensive, but the present invention uses the difference in water head of the inflow fluid as the power, so it is simple and inexpensive as no separate power is required. It has the advantage of being able to be made.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIGS. 1 and 2).

This embodiment is applied to a weir type flowmeter.
A lid 12 is attached to the main body 10 of the casing, and a measurement chamber 14 is formed inside. A cylindrical partition member 16 with a bottom is arranged in the measurement chamber 14 . Partition member 16
A vertically long weir 18 and a communication hole 20 are formed above the weir in the side wall. The inner space of the partition member 16 is connected to the entrance 22,
The outer space is connected to the outlet 24 through a riser passage.

A cylindrical partition member 26 is vertically attached to the lid 12 in an airtight manner. A hollow float 28 is arranged around the partition member 26. The float 28 has a guide tube 30 airtightly fixed along the central axis of a spherical shell 29. Therefore, the float 28 is freely displaceable in the axial direction of the partition member and rotatable in the circumferential direction. An annular magnet 32 is attached to the guide tube 30.

Support members 34, 36, 38 are mounted on top of lid 12 and potentiometer 40 is secured. Potentiometer 40 is covered with cap 42. The electric wires and necessary electrical parts housed in this are not shown.
Omit explanation. Operation rod 4 of potentio meter 40
4 extends downward inside the partition member 26, and a cylindrical magnet 46 is attached at a position facing the magnet 32. One of the magnets 32 and 46 may be a magnetic material.

The magnetic joint made up of the magnet 32 and the magnet 46 is the operating rod 4.
Magnetic force is required to support 4 and displace it. A slide ring 48 made of fluororesin is attached below the magnet 46 of the operating rod 44.

A radially projecting vane 50 is provided on the outer surface of the spherical shell 29 of the float 28. The vane 50 is provided at a position where it is submerged in the liquid when the flow rate is minute.

A bank member 52 having a U-shaped cross section is attached above the partition member 16 from the entrance 22 along the inner circumferential wall of the main body 10. The inner wall of the embankment member 52 extends from the entrance 22 to approximately a semi-circumference, and has an opening at the tip of the partition member 16.
It is open in the direction of rotating the fluid inside the partition member, that is, in the tangential direction of 16 of the partition member. Embankment member 5
2, a partition wall 54 of about half the height is provided, and an inverted U-shaped pipe 56 is attached thereto. The top of the inverted U-shaped tube is located below the top of the partition wall 54,
The inner opening extends to the vane 50 and allows fluid to flow into the interior of the partition member 16 in a rotational direction, that is, in a tangential direction to the partition member 16. The diameter of the inverted U-shaped pipe 56 is 0.8~
A pore 58 of about 1.5 mm is opened.

Therefore, the inflowing liquid that enters from the inlet 22 first accumulates in the portion of the bank member 52 surrounded by the partition wall 54. When the amount of inflow is small, it intermittently flows into the liquid through the inverted U-shaped tube 56. If the amount of inflow is large, it will continuously flow into the liquid through the inverted U-shaped pipe 56. If the amount of inflow is large, in addition to this, the water will overcome the partition wall 54 of the bank member 52 and flow down from the opening of the bank member 52 around the float 28 .

The liquid inside the partition member 16 is rotated by the fluid flowing through the inverted U-shaped tube and over the partition wall 54 of the bank member 52. The float 28 rotates indirectly due to the action of viscosity, and floats up and down along with the liquid level inside the partition member 16. The displacement of the float 28 is transmitted to the operating rod 44 through a magnetic coupling (magnets 32, 46), and the output signal of the potentiometer 40 changes. The fluid inside the partition member 16 flows out through the weir 18 and out to the outlet 24. Partition member 16
The relationship between the position of the liquid level inside the weir 18 and the amount flowing out from the weir 18 is measured in advance, and the potentiometer 4
The flow rate is calculated and determined from the output signal value of 0.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment in which the invention is applied to a weir type flowmeter, and FIG. 2 is a sectional view taken along the line -- in FIG. 14: Measurement room, 16: Partition member, 18: Weir, 2
2: Inlet, 24: Outlet, 26: Partition member, 28:
Float, 32: Magnet, 40: Potentiometer, 44: Operation rod, 46: Magnet, 50: Vane, 5
2: Embankment member, 54: Partition wall, 56: Inverted U-shaped pipe, 5
8: Pore.

Claims (1)

[Claims] 1. A float is attached to the outside of a cylindrical partition wall so as to be freely displaceable in the axial direction and rotatable in the circumferential direction,
The float and the operating rod of the electric signal converter are connected by a magnetic joint with a partition wall in between, and a bank member having an inlet for inflowing liquid at one end and an opening for allowing the inflowing liquid to flow in a tangential direction of the float at the other end, A partition wall, which is provided above the float and whose upper end is located below the upper end of the bank member, is provided in the middle of the bank member to form a reservoir for the inflow liquid at one end of the bank member, and one end is placed inside the reservoir and another partition wall is provided in the middle of the bank member. Arrange an inverted U-shaped tube whose end opens into the liquid surrounding the float and whose uppermost part is located below the upper end of the partition wall, and the other end of the inverted U-shaped tube opens in the tangential direction of the float. Liquid level detection structure with pores at the top of the falling U-shaped tube. 2. The liquid level detection structure according to claim 1, wherein the float is provided with vanes so as to be susceptible to rotational force from the inflowing liquid.