JP2002340655A - Level switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate mechanical driving for switch operation to allow the constitution of a level switch only with magnetic coupling by attaching directly a magnet to the operation lever of a microswitch constituting of the level switch, so as to provide a simple and highly reliable level switch for monitoring and controlling the liquid level of a tank or the like. SOLUTION: The highly precise and reliable level switch of simple constitution is constituted by providing a float arm for measuring the level of a liquid in the tank, by attaching a magnet to an end of the front arm, and by providing the magnet directly to the operation lever of the microswitch for detecting an arm position outside the tank in a position facing to the magnet via a non- magnetic member for sealing the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility for measuring a liquid level, particularly to a tank which is attached to a side surface thereof, and detects a liquid level at the position. It also relates to a level switch that can be used to control the liquid level.

[0002]

2. Description of the Related Art Conventionally, such a level switch uses a microswitch 7 in a detecting section as shown in FIG.
0. Normally, it is desirable that the level switch mounted on the side of the tank be completely sealed in order to prevent the liquid from flowing out of the tank. Therefore, inside the tank,
The outside of the tank is structurally completely shut off. For this reason, position information of the float arm for detecting the liquid level in the tank needs to be transmitted to the detection unit outside the tank in a non-contact manner.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and transmits the position of a float arm for detecting a liquid level in a tank to a detection unit outside the tank in a non-contact manner. Specifically, a magnet attached to the end of the float arm in the tank and a magnet installed at a position opposite to the magnet outside the tank via a non-magnetic seal to prevent the liquid from flowing out of the tank The microswitch is actuated by driving the attached latch. In order to secure a space for the latch 10 for operating the microswitch, it is necessary to enlarge the switch cover.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a magnet provided outside a tank and directly provided on a microswitch operating lever of a detection unit for detecting a position of a float arm in the tank. By using only magnetic coupling for mounting and driving the detection unit, the mechanical movable unit can be omitted.

Further, according to the present invention, at least two magnets are attached to the micro switch operating lever,
At least one is of opposite polarity. Thereby, the micro switch operation lever can be operated in the opposite direction by the magnet attached to the tip of the float arm in the tank. That is, the contacts can be reliably opened and closed. Also, by closing the contact state when it is not operated, it can be used for an alarm using the contact of the microswitch.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention.
It will be described based on. FIG. 1 shows an embodiment of the present invention. As shown in FIG. 3, this level switch is usually mounted on the side of the tank and used to detect the liquid level at that position. It is composed of a magnet 5 attached to the tip of a float arm 4 in the tank, and a microswitch 7 attached to a position opposite to the magnet 5 via a non-magnetic sealing member.

Next, referring to FIG. 3, an example of a method of installing the level switch will be described. In FIG. 3, an upper limit level switch 2 is attached to the upper side of the tank 1, and a lower limit switch 3 is attached to the lower side of the tank. Tank 1
The liquid level inside is at the middle of these level switches. At this time, the upper limit level switch 2 and the lower limit level switch 3 are both inactive, and the micro switch contacts are closed. That is, the upper limit level switch 2 and the lower limit level switch 3 are mounted in the vertical direction. On the other hand, it is also possible to mount in the same direction in the vertical direction.

When the microswitch is in a non-operating state, the microswitch contact is in a closed state, so that a current can be passed through this contact to be used for an alarm such as a failure of the contact.

Next, FIGS. 5 and 6 show an operation state of the micro switch contact of FIG. 1 showing one embodiment of the present invention. FIG. 5 shows that the magnet attached to the distal end of the operating lever 6 of the micro switch 7 corresponds to the rotation direction of the magnet 5 attached to the distal end of the float arm 4 in the tank. Magnet 5 attached to the tip
And the same polarity, the contact of the microswitch 7 is closed.

FIG. 6 shows that the micro switch 7 is attached to an intermediate portion of the operation lever 6 of the micro switch 7 with respect to the rotation direction of the magnet 5 attached to the tip of the float arm 4 in the tank. Since the polarity of the magnet is opposite to that of the magnet 5 attached to the tip of the float arm 4, the contact of the microswitch 7 is opened.

Further, as shown in FIG.
Can be protected by a non-magnetic material.

Another embodiment of the present invention will be listed. FIG. 8 can provide a level switch having the same structure as that of the present invention but having a simpler structure. That is, the non-magnetic sealing body shown in FIG. 1 is usually formed by welding a stainless steel plate to an iron flange. FIG. 8 shows that the welded portion can be omitted by using only the stainless steel plate, and as a result, even if the welded portion is defective, leakage of the liquid in the tank from the welded portion can be prevented. .

[0013]

According to the present invention, the level switch can be made smaller by driving the microswitch only by magnetic coupling by the magnet 5 attached to the tip of the float arm 4 in the tank. Further, the manufacturing accuracy of the level switch and the overall configuration can be simplified.

[0014]

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a conventional level switch.

FIG. 3 is a diagram showing a mounting state of the present level switch.

FIG. 4 is a diagram showing a non-operating state of a contact of a conventional level switch.

FIG. 5 is a diagram illustrating a relationship between a switch closed state of the microswitch and a magnetic field.

FIG. 6 is a diagram illustrating a relationship between a switch closed state of the microswitch and a magnetic field.

FIG. 7 is a diagram illustrating a contact stop portion made of a non-magnetic material.

FIG. 8 is a diagram showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 2 Upper limit level switch 3 Lower limit level switch 4 Float arm 5 Magnet 6 Operating lever 7 Micro switch 8 Magnet 9 Magnet 10 Latch 11 Contact part

Claims (3)

[Claims] 1. A magnet attached to an end of a float arm in a tank, a magnet attached to a micro switch operating lever outside the tank at a position opposite to the magnet, and a non-magnetic sealing member interposed therebetween. Level switch characterized by the configuration. 2. The level switch according to claim 1, wherein the number of magnets attached to the micro switch operating lever is at least two, and at least one of them has opposite polarity. 3. The level switch according to claim 1, wherein the contact of the micro switch is closed when the micro switch is not operated.