US2142680A - Float control switch - Google Patents

Description

Jan. 3, 1939. s o j 2,142,680

FLOAT CONTROL SWITCH Filed July 12, 1937 2 Sheets-Sheet l W I I123 a .2 27 .l.

Jan. 3, 1939. J H 2,142,680

FLOAT CONTROL SWI TCH Filed July 12, 1937 2 Sheets-Sheet 2 Jufzzz L Shrade Patented Jan. 3, 1939 UNITED STATES FLOAT CONTROL swrrcn John L. Shrode, Richmond Heights, Mo., assignor to Alco Valve Company, Inc., St. Louis, Mo.

Application July 12, 1937, Serial No. 153,253

5 Claims.

This invention relates to electrical circuit make and break mechanism in general; and more particularly to mechanism of this character operable in response to variations in level of a liquid in any 5 vessel to control the supply of liquid thereto.

The main object of the invention is to provide a float controlled switch of the explosion-proof type adapted for use in hazardous atmospheres, such as are encountered in oil' level control during the refining processes, whereby the level of highly volatile products, such as alcohol, ether, and refrigerant liquids, may be controlled without danger of ignition caused by sparks which would ordinarily result by the operation of switches having electrical conducting surfaces exposed to the explosive atmosphere.

Other objects of the invention will become apparent as the detailed description thereof proceeds.

In the drawings:

Figure 1 is a central vertical section through one form of the invention;

Figure 2 is a horizontal section taken on the line 22 of Figure 1;

Figure 3 is a central vertical section to a modified form of the invention; and

Figure 4 is a horizontal section taken on the line 44 of Figure 3.

Referring now to Figures 1 and 2 of the drawings, the invention comprises a cylindrical body 5 closed at its lower end by a bottom plate 6, having an internally screwthreaded liquid connection 1 formed thereon. A body plate 8 suitably secured to the body 5 near the upper end thereof, forms with said body 5 and bottom plate 6, a pressure chamber 9. the body plate and bottom plate being suitably secured to the cylindrical body 5 as by Welding or otherwise. A gas connection is provided in the body near the upper end of the chamber 9, the said gas connection l0 and liquid connection 7 serving to connect the pressure chamber 9 in parallel with any vessel designed to have its liquid level controlled in accordance with the level of liquid in the said pressure 45 chamber.

The body plate 8 is provided at its center with an aperture H in which is suitably secured the lower end of a non-magnetic tube I2, the upper end of which serves as a support for the top l3 of the relay housing l4. The relay housing I4 is cylindrical and of substantially the same diameter as that of the cylindrical body 5. The lower end of the housing is laterally offset to form an annular flange l5 adapted to fit snugly over the upper end of the body 5.

The shoulder formed in the lower edge of the housing l4 by the annular flange I5 is provided with an annular recess IS in which is seated the relay housing gasket ll of rubber, or other suitable resilient material. The upper end of the tube i2 is closed by a plug l8 having an externally screwthreaded shank l9 projecting axially through an aperture 20 formed in the center of the top l3 of the relay housing. A nut 2| engages the shank l9 to clamp the housing l4 securely against the gasket l7, and thereby form an effective airtight casing for the electric circuitclosing mechanism above referred to.

The relay or switch mechanism is mounted on and surrounds the non-magnetic tube 12. This mechanism comprises a permanent magnet 22 having the arms 23 and 24 thereof apertured to fit snugly over the tube l2. The magnet 22 is supported in vertical position on the tube l2 by means of a fiber tube 25, the bottom of which rests upon the body plate 8, and the upper end of. which contacts with and supports the lower arm 24 of the magnet 22. A short section 26 of fiber tube extends between the upper arm 23 of the magnet and the lower surface of the top ii of the housing l4, to clamp the magnet 22 securely in position on the non-magnetic tube II.

A float 21 is arranged within the pressure chamber 9, and has a rod 28 extending from its upper end axially into the tube l2. A plunger 29 of magnetic material is secured to the upper end of the rod 28. The non-magnetic tube l2 completely encloses the plunger 29 and the rod connecting it to the float. 21, and is of sufficient length to permit the necessary axial movement of the plunger in response to liquid level change as imposed upon the float 21 by change in level of the liquid in the pressure chamber 9.

An armature 30 for the magnet 22 is pivoted at its lower end to the arm 24 of the magnet. A pair of tension springs 3i and 32 are secured at one of their ends to the magnet arm 24 and at their other ends are secured to 2. lug 33 projecting from the lower end of the said armature. Normally these tension springs would hold the armature in the dotted line position shown in Figure 1, with its upper end separated from the upper arm 23 of the magnet. However, the tension of these springs is predetermined so that the attraction of the magnet for the armature will hold it in the full line position shown in the drawings to provide a closed magnetic circuit for the lines of force of the magnet.

When the float supported plunger 29 is raised to a position within the tube [2 in which it comto the lower part of the armature fill and having,

a contact terminal 35 fixed to its outer end adapted to make contact with a cooperating terminal 35 fixed to a bracket 3'? insulated from and suitably secured to the relay housing 96. Suitable wires ti and 38 connect the respective tenals 35 and 3b to any apparatus designed to be controlled thereby. A conduit connection as is secured to the upper end of the body 5 above the body plate 8 to serve as a passageway for such wiring as may be necessary to connect the relay to the said apparatus.

The modified form of the invention illustrated in Figures 3 and 4 is substantially the same as that shown in Figures 1 and 2. In this form, however, an electrical induction coil in and a magnetic fr'ame dl are substituted for the permanent magnet 2'2, shown in Figure 1, the coil it being retained in place between the arm or pole pieces t2 and 63 by means of a screw dd pass ing freely through an aperture in the pole piece 42 and screwthreaded into an internally screwthreaded aperture in the lower pole piece 53. The armature and other operating parts connected thereto are substantially the same as the corresponding parts shown in Figure l and are identi-' fled by the same reference numerals.

when low temperatures are encountered, such as commonly occur in refrigerated vessels, it is desirable to isolate the relay mechanism so as'to permit insulation of the pressure chamber 9, in order that violent ebullition created by high rates of heat absorption will not cause false liquid levels within the float chamber. It is also desirable to effect this isolation and insulation in order to prevent freezing of the mercury within the mercury switches, when switches of this character are used within the relay housing.

The insulation above referred to comprises a block of cork t5, centrally apertured to receive the non-magnetic tube as secured at its lower end to the body plate d. The tube 38 is substantially the same asthe tube 52, shown in Figure 1 of the drawings, and is similarly secured at its I upper end to the relay housing it, which in every respect is the'same as that shown in Figure 1. The tube it must, of course, be correspondingly lengthened to compensate for the length of the insulation insert 65. The lower end of the relay enclosing chamber is formed by a cylindrical container fill, the bottom of which is centrally apertured to receive the tube (it, and is provided with an upstanding annular boss or flange is serving as a seat for the lower end of the tube 25', which forms a support for the magnetic frame ll. The other elements of this form of the invention are the same as are shown in Figure 1 of the drawings and are identified by the se reference numerals.

While the switches shown in the drawings are of the common spring contact type, it must be understood that the invention is not to be considered as limited to any particular kind of switchaisao a non-magnetic tube extending through the pole pieces thereof, an armature pivoted to the end of one of said pole pieces to swing toward and from the other pole piece and normally held by said magnet in position to close the magnetic circuit therethrough, means for swinging said armature away from said other pole piece when the flux through the magnet is shunted from said armature, aplunger of magnetic material slidable in said tube to bridge said pole pieces, and a I circuit maker and breaker connected to said armature ior operation by the movements thereof.

2. Liquid level-controlled electric switch mechanism, comprising a casing, a partition dividing the casing into a liquid-containing chamber and a relay housing, a horse shoe magnet mounted in said housing, a non-magnetic tube extending from said chamber through said partition and the pole pieces of said magnet, an armature pivoted to one of said pole pieces to swing toward and from the other pole piece and normally held by said magnet in position to close the magnetic circuit therethrough, means for swinging the armature from said circuit-closing position when the flux through the magnet is shunted from said armature, a float within said chamber, a plunger connected to said float and slidable. in said tube from the other pole piece and normally held by said magnet in position to close the magnetic circuit thereth, means for swinging the armature from said circuit-closing position when the flux through the magnet is shunted fromsaid armature, a float within said chamber, a plunger connected to said float and slidable in said tube transversely of said pole pieces to shunt said armature, and a circuit er and breaker connected to said armature for operation by the swinging movements thereof, said partition and tube forming an hermetic seal between said chamber and the circuit-closing mechanism in the relay housing.

4. Liquid level-controlled switch mecha comprising: a -21 a partition dividing the casing into a liquid container and a relay housing, a tube of non-magnetic material extending,

2,142,eao

in said tube.

5. A switch comprising a horse shoe magnet. an

armature pivoted at one 5 pieces of said magnet to the other pole piece an end to one 01' the pole swing toward and from d normally held by said magnet in position to close the magnetic circuit across said pole pieces, means for swinging the armature away from said other pole piece, and

circuit make and break mechanism operably controlled by the swinging of said armature.

- JOHN L. SHRODE.

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