JPH0372937B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a liquid level detection method used to measure the position of liquid level in a waterway or tank, or to measure the position of liquid level upstream of a weir type flowmeter. Concerning the structure of the vessel. In particular, the present invention relates to the structure of a portion that uses a float to detect the position of the liquid level and converts the displacement of the float into an electrical signal.

Conventional technology The structure of a conventional liquid level detector is, for example,
This is shown in Publication No. 35226. This involves placing a cylindrical bulkhead in the vertical direction, placing a float slidably on the outside of the bulkhead, inserting the operating rod of a potentiometer inside the bulkhead, attaching a magnet to the float and the operating rod, and attaching a magnet to the bulkhead. They are fixed so that they face each other with the two sides in between. 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. The water level is detected by measuring the change in resistance due to changes in the sliding contact of the operating rod.

Problems to be Solved by the Invention In this case, there is a problem of poor liquid level measurement accuracy.
This is because the change in electrical resistance detected by the potentiometer is an analog value and is susceptible to noise.

The technical problem of the present invention is to enable the water level to be detected directly as a digital value.

Means for Solving the Problems The technical means of the present invention taken to solve the above technical problems is to arrange a float on the outside of a cylindrical partition wall, attach an annular internal magnetic body to the float, An external magnetic body is placed facing the internal magnetic body across a partition wall, an operating rod is attached to the external magnetic body, and a number of light reflecting parts are formed on the outer peripheral surface of the operating rod at regular intervals above and below. At least 3 rows of reflective rows are formed, and the reflective part of each reflective row is formed so as to be lower at a constant rate with respect to the reflective row on one side, and the top of each reflective row is formed with the same height. A reflective optical sensor is arranged at a position facing each reflective row, and a direction determining means for determining whether the float is ascending or descending from the pulse of reflected light received by each optical sensor is connected to the optical sensor. However, a counting means for adding or subtracting based on the signal from the direction determining means is provided.

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

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. The light from each optical sensor is reflected from the reflecting part in accordance with the displacement of the operating rod, returns to each optical sensor, and can be captured as a pulse depending on whether it is reflected or not. By counting these pulses, the water level can be detected as a digital value. The determination of the ascent and descent of the float is at least 3
The pulses are counted in the order of the pulses reflected from the reflective sections arranged in rows. Zero water level detection is performed using a reflective section installed at the top.

Unique effects The present invention produces the following unique effects.

In the present invention, since the water level can be directly detected as a digital value, the water level can be accurately measured without noise.

Since the direction determining means and the counting means are provided, the resolution can be improved by reducing the vertical distance between the reflecting parts, regardless of the number of optical sensors.

Embodiment An embodiment illustrating a specific example of the technical means of the present invention will be described (see FIGS. 1 to 3).

This embodiment is applied to a weir type flowmeter.

A lid 2 is attached to the main body 1 with bolts to constitute a casing of the measuring instrument. A substantially cylindrical space is formed inside the casing, and a cylindrical weir 10 is formed inside the casing.
Attach. An inlet 8 communicates with the inside of the weir 10 through a cylindrical screen 22. The peripheral wall of the weir tube 10 has a V-shaped opening, that is,
A weir 11 is opened, and a communication hole 12 is made in the upper part of the weir. The inside and outside of the weir tube 10 communicate through the weir 11 and the communication hole 12, and the outside space communicates with the outlet 9 through a rising passage.

A cylindrical partition member 1 is located approximately in the center of the weir tube 10.
3 is placed vertically through the lid 2. The lower end of the partition member 13 is closed. A hollow float 18 is arranged outside the partition member 13. A tube that fits into the partition member 13 is attached along the central axis of the float 18, and an annular magnet 20 is fixed to the outer periphery of the tube.

A heat insulating plate 3 and support members 4 and 5 are mounted on top of the lid 2, and optical sensors 21, 22 and 23 are fixed thereon and covered with a cap 6.

Insert the operating rod 14 into the partition member 13. The operating rod 14 has a cylindrical shape and has a magnet 19 attached to its lower end. The operating rod 14 is prevented from rotating by a groove 27 and a pin 28. The operating rod 14 is prevented from tilting by guides 29 and 30.

A light reflecting portion 24 is printed on the outer peripheral surface of the operating rod 14. The parts other than the reflecting part 24 are light absorbing parts. A large number of reflecting parts 24 are provided vertically at regular intervals,
In this embodiment, three rows are formed. The best reflector 2
5 are formed at the same height. The reflecting section 24 is the third
In the figure, the rows are gradually lowered at a constant rate with respect to the left column. Optical sensors 21 , 22 , and 23 are fixed facing each reflection row of the reflection section 24 .

The liquid flows into the diaphragm 10 from the inlet 8,
It flows out through weir 11 to outlet 9. Since there is a certain relationship between the flow rate of liquid passing through the weir 11 and the liquid level inside the weir 10, by measuring the liquid level inside the weir 10, the liquid passing through the weir 11 can be measured. The flow rate can be determined.

The liquid level is detected by the float 18, and the magnets 19, 20
The operating rod 14 is displaced through the . Optical sensor 2
The light from 1, 22, and 23 is reflected from the reflection part 24 according to the displacement of the operating rod 14, returns to each optical sensor, and is captured as a pulse depending on whether it is reflected or not. By counting these pulses, the water level is detected as a digital value.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a weir-type flowmeter to which an embodiment of the present invention is applied, and FIG. 2 is a sectional view taken along the - line in FIG. 1.
FIG. 3 is a side view of the operating rod developed. 13: Bulkhead, 14: Operation rod, 18: Float,
24: Reflector, 21, 22, 23: Optical sensor.

Claims (1)

[Claims] 1 Place a float on the outside of the cylindrical partition wall,
An annular internal magnetic body is attached to the float, an external magnetic body is placed facing the internal magnetic body across the partition wall, an operating rod is attached to the external magnetic body, and a light reflecting part is placed on the outer peripheral surface of the operating rod. A large number of reflective rows are formed at regular intervals, and at least three reflective rows are formed.
The reflective parts of each reflective row are formed so that they are lower at a constant rate relative to the reflective row on one side, and the reflective parts of the same height are provided at the top of each reflective row. A reflective optical sensor is arranged at a position facing the optical sensor, and direction determining means for determining whether the float rises or falls from the pulse of reflected light received by each optical sensor is connected to the optical sensor, and based on the signal from the direction determining means. A liquid level detection structure equipped with a counting means for adding or subtracting.