JPH0119300Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a level switch that detects the position of a liquid level in a container using gas pressure and outputs an electrical signal.

Conventionally, various instruments are known for detecting a liquid level and outputting a display or signal. In other words, a method of measuring the moving distance or buoyancy of a float by floating it on the liquid surface, a method of measuring the liquid pressure applied to a diaphragm, a method of measuring the pressure of gas while bubbling the gas from a measurement nozzle, and a method of measuring the pressure of the gas by bubbling it from a measurement nozzle. A method to determine whether the liquid is below the surface by the mechanical resistance experienced by the body, a method to detect the difference in acoustic impedance by applying ultrasonic vibration, a method to measure the degree of attenuation due to radiation transmission, permittivity and conductivity There are methods that use methods such as detecting the difference between

Among them, a method in which gas is bubbled into the liquid from a measurement nozzle immersed in the liquid and the pressure of the gas supplied to the measurement nozzle is measured is as shown in Figure 2. It is sent to the measuring nozzle b via the aperture a to cause bubbles to form in the liquid, and the aperture a
The pressure of the gas after is measured by a pressure gauge c,
This determines the distance from the liquid level to the tip of the measuring nozzle b, that is, the immersion depth of the measuring nozzle b. This method has the advantages of a relatively simple mechanism, can be used even in harsh environments, and is easy to maintain.

Therefore, in order to control the liquid level position using this method, a method has been proposed in which a level switch capable of detecting gas pressure and opening/closing an electrical signal circuit is used instead of the pressure gauge c described above. . As shown in Fig. 3, such a level switch is configured so that the movement of a diaphragm d, which receives gas pressure on one side, is received by a micro switch e provided on the other side to open and close contacts f and g. However, in order to increase the sensitivity, it is necessary to use a large diaphragm, and since a micro switch is used, it is difficult to reduce the hysteresis of the opening/closing operation. In order to improve the accuracy of the opening and closing operation, the diaphragm itself must have elasticity, so the operating pressure is 50 mm in the water column.
Highly reliable operation could not be expected unless the situation was more than moderate.

The present invention eliminates the drawbacks of the conventional level switch as described above, and can operate with high reliability and high sensitivity at minute pressures of, for example, 10 mm or less in the water column. The object of the present invention is to provide a small-sized gas pressure type level switch that is capable of accurate detection and that can extremely easily change and adjust the operating pressure level.

The gas pressure type level switch of the present invention has the following features:
a microswitch as a control output switch; a first diaphragm having a pin for driving the switch connected to one surface and the other surface forming one wall of the first air chamber; A first orifice that limits the flow rate of working gas flowing into the air chamber, a second orifice that limits the flow rate of working gas flowing out from the first air chamber, and a control nozzle that divides the working gas from the first air chamber. a second diaphragm having one surface close to the tip of the control nozzle and the other surface forming one wall of the second air chamber;
A control valve controls the flow rate of the detection gas flowing into the air chamber, and the gas flowing out from the second air chamber is introduced and released from the tip placed near the liquid level to be detected. a liquid level detection nozzle, the control nozzle is provided with a ridge on the outer periphery so that the nozzle tip can be moved toward or away from the second diaphragm; The present invention is characterized in that the working gas and the detection gas are branched and supplied from gas passages passing through the body from side to side.

The present invention will be explained below based on the figures.

FIG. 1 shows the structure of an embodiment of the gas pressure type level switch of the present invention. 1 is a micro switch for outputting a control signal by detecting the liquid level, and is operated by a drive pin 6 passing through a cover 2. It's starting to work. A body 3 is provided below the cover 2 in contact with it, and a space 7 communicating with the outside of the device is provided between a first diaphragm 8 attached therebetween and the cover 2, and the driving pin 6 is connected to the first diaphragm 8. is driven according to the movement of A first air chamber 9 is formed between the first diaphragm 8 and the body 3. 10 is a first orifice that limits the flow rate of working gas flowing into the first air chamber 9, and 11 is a second orifice that limits the flow rate of working gas flowing out from the first air chamber 9. Further, working gas can flow out from the first air chamber 9 through a passage in a control nozzle 12 provided along the central axis of the body 3 from the tip 12a.

A second diaphragm 14 is attached between the body 3 and a base 4 provided below. A space 13 that communicates with the outside of the device is formed between the second diaphragm 14 and the body 3, and the working gas leaking from the gap between the tip 12a of the control nozzle 12 and the second diaphragm 14 flows from the space 13. It passes through the outlet 21 and flows out of the vessel. Further, a second air chamber 15 is formed between the second diaphragm 14 and the base 4, into which the detection gas flows through the needle valve 17, and further passes through the nipple 16 to the liquid level detection nozzle (Fig. (not shown)
I am beginning to be guided by this.

Reference numeral 5 denotes a manifold that supplies working gas and detection gas in a branched manner, and is provided with a gas passage 18 penetrating in the left-right direction, and supplies working gas to the first orifice 10 via a branch passage 19, and also to a branch passage 20. The detection gas is guided to the needle valve 17 via the needle valve 17 .

The rear half of the level switch body is manifold 5
A gas outlet 21, a nipple 16, and a hole for operating a needle valve 17 are provided on the front side of the main body (left side in the figure). The cover 2, body 3, base 4, and manifold 5 of the level switch body have flat sides, no protrusions, and are uniform in width.
They can be lined up horizontally without any gaps. If a plurality of level switches of the present invention are lined up and tightened laterally, one end of the gas passage 18 is connected to a gas supply source, and the other end is provided with a blind stopper, the gas passage 18 as a whole forms one gas supply passage. I will do it.

Furthermore, in the level switch of the present invention, a male thread 12b is provided on the outer periphery of the control nozzle 12 and is connected to a female thread provided inside the body 3, so that the control nozzle 12 can be rotated. Therefore, it can be moved up and down, and as a result, the tip of the control nozzle 12 can be brought closer to or separated from the second diaphragm 14.

Now, rotate the control nozzle 12 so that its tip approaches the second diaphragm 14, and then open the nipple 1.
For example, a gas conduit having a liquid level detection nozzle attached to the tip thereof is connected to 6, and gas is supplied from the gas passage 18. At this time, the pressure of the gas flowing out through the nipple 16 is applied to the lower surface of the second diaphragm 14, and the gas in the first air chamber 9 flows out from the gap between the second diaphragm 14 and the control nozzle 12. The gas is further discharged to the outside of the vessel through the gas outlet 21.

In such a state, when the outflow of gas from the nipple 16 is controlled, for example by immersing the liquid level detection nozzle in the liquid and causing gas to bubble out, the pressure in the second air chamber 15 decreases. increases, the second diaphragm 14 is pushed up, and the control nozzle tip 1
2a and the second diaphragm 14 becomes narrower, and the outflow of the working gas from the control nozzle 12 rapidly decreases, so the internal pressure of the first air chamber 9 increases and the first diaphragm 8 is pushed up, and as a result, the drive pin 6, the micro switch 1 is switched. In this way, when the outflow suppression for the gas flowing out from the nipple 16 changes slightly, the second air chamber 1
The pressure inside the microswitch 5 changes, and this pressure change is amplified by the control nozzle 12 to change the pressure in the first air chamber 9, causing the microswitch 1 to operate sharply.

For example, when the gas pressure type level switch of the present invention is operated by supplying air with a gauge pressure of 0.2 kg/cm ² to the gas passage 18, the tip of the liquid level detection nozzle connected to the nipple 16 is slightly submerged by 7 mm. Micro switch 1 was activated after being immersed for only a short time. At this time, the number of air bubbles was approximately 1 per second, and since the liquid level was not disturbed by bubbles, the reproducibility of the operating pressure level was extremely accurate at ±1 mm in the water column.

Further, by separating the tip 12a of the control nozzle 12 from the second diaphragm 14, the operating pressure can be increased. That is, the second diaphragm 14 does not close to the tip 12 of the control nozzle 12 until the detection nozzle goes deep into the liquid and the detection gas is difficult to bubble out (therefore, the pressure inside the second air chamber 15 is considerably high).
a, and the increase in pressure within the first air chamber 9 slows down.

In this way, by moving the control nozzle 12 up and down, it is possible to change the depth of the liquid level detection nozzle tip into the liquid, that is, the detected pressure value, without significantly reducing the detection sensitivity, which is not necessary in the past. This makes it possible to omit the troublesome work of finely adjusting the mounting position of the liquid level detection nozzle.

Since the gas pressure type level switch of the present invention has the above-mentioned configuration and functions, the installation and adjustment work is greatly streamlined, and it has high accuracy and sensitivity in terms of performance, as well as a wide range of adjustment range. Due to its large size, it has the advantage that it can be applied not only to liquid level detection but also as various air pressure sensors such as proximity switches, and can meet a variety of requirements. This has the double advantage that the cost of installing the equipment is also improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of a gas pressure type level switch according to the present invention. Further, FIG. 2 is an explanatory diagram of the principle of the bubble type liquid level detection method, and FIG. 3 is a sectional view of an example of a conventional pressure level switch used therein. 1...Micro switch, 2...Cover, 3...
...body, 4...base, 5...manifold,
6... Drive pin, 7... Space, 8... First diaphragm, 9... First air chamber, 10... First orifice, 11... Second orifice, 12... Control nozzle, 13... Space , 14...second diaphragm,
15...Second air chamber, 16...Nipple, 17...
Needle valve, 18... Gas passage, 19, 20
... Branch passage, 21 ... Gas outlet, 22,2
3, 24, 25...O-ring.

Claims (1)

[Scope of utility model registration request] a microswitch as a control output switch; a first diaphragm having a pin for driving the switch connected to one surface and the other surface forming one wall of the first air chamber; A first orifice that limits the flow rate of working gas flowing into the air chamber, a second orifice that limits the flow rate of working gas flowing out from the first air chamber, and a control nozzle that divides the working gas from the first air chamber. a second diaphragm having one surface close to the tip of the control nozzle and the other surface forming one wall of the second air chamber;
A control valve controls the flow rate of the detection gas flowing into the air chamber, and the gas flowing out from the second air chamber is introduced and released from the tip placed near the liquid level to be detected. a liquid level detection nozzle, the control nozzle is provided with a ridge on the outer periphery so that the nozzle tip can be moved toward or away from the second diaphragm; 1. A gas pressure type level switch characterized in that the working gas and the detection gas are configured to be branched and supplied from a gas passage passing through the body from side to side.