JPH0245131B2 - - 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 with a magnetic joint across the partition wall, and a reservoir for the inflow fluid is provided above the float, with one end in the reservoir and the other end in the liquid surrounding the float. An open inverted U-shaped tube was placed, and the other end of the inverted U-shaped tube was opened in the connection direction of the float so as to rotate the liquid around the float, and a pore was provided at the top of the downward slope of the inverted U-shaped tube. , is a thing.

Effect The operation of the above technical means is as follows.

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 pressure around the float, and the liquid level of the inflowing fluid in the reservoir remains constant. When it reaches a height of , it is introduced into the liquid around the float through an inverted U-shaped tube, causing the liquid around the float to rotate. The float rotates indirectly due to the action of viscosity.

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.

Since a predetermined amount of liquid is allowed to flow in through the inverted U-shaped tube, the float can be reliably rotated even if the amount of incoming fluid is minute.

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 FIG. 1).

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 support member 5 having an L-shaped cross section is placed above the partition member 16.
2 to form an annular groove 54 between the inner wall of the main body 10 and the inner wall of the main body 10. Then, an inverted U-shaped tube 56 is attached across the support member 52. The uppermost part of the inverted U-shaped tube 56 is located below the upper end of the support member 52, and the inner opening extends to the position of the blade 50, and the direction in which the fluid is rotated inside the partition member 16, that is, the tangent of the partition member 16 is flow in the direction.
Diameter 0.8~ on the straight pipe part at the top of the falling inverted U-shaped pipe
Open a pore of about 1.5mm.

Therefore, the inflow fluid entering from the inlet 22 first collects in the annular groove 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 flow over the support member 52 and flow down around the float.

The liquid inside the partition member 16 is reheated by the fluid flowing in through the inverted U-shaped tube. 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. float 2
8 is transmitted to the operating rod 44 through the magnetic coupling (magnets 32, 46), and the output signal of the potentiometer 40 changes. The liquid inside the partition member 16 flows through the weir 1
8 and out to outlet 24. The relationship between the position of the liquid level inside the partition member 16 and the amount flowing out from the weir 18 is measured in advance, and the potentiometer
The flow rate is calculated and determined from the output signal value of the meter 40.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment in which the present invention is applied to a weir type flowmeter. 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
4: Liquid reservoir annular groove, 56: Inverted U-shaped tube, 58: 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 with a magnetic joint across a partition, and a reservoir for the inflow fluid is provided above the float, with one end opening into the reservoir and the other end opening into the liquid surrounding the float. A liquid level detection system in which a U-shaped tube is arranged, the other end of the inverted U-shaped tube is opened in the tangential direction of the float to rotate the liquid around the float, and a small hole is provided at the top of the falling edge of the inverted U-shaped tube. structure. 2. The liquid level detection structure according to claim 1, wherein the float is provided with vanes so as to be easily subjected to rotational force by the inflowing fluid.