US2120048A

US2120048A - Electric float control

Info

Publication number: US2120048A
Application number: US33796A
Authority: US
Inventors: Turner Jacob Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-07-29
Filing date: 1935-07-29
Publication date: 1938-06-07
Anticipated expiration: 1955-06-07

Description

June 7, 1938. J R R 2,120,048

ELECTRIC FLOAT CONTROL Filed July 29, 1935 2 Sheets-Sheet 2 .E7U6W'UO7' JACOB LEE TURNER,

b MA Patented June 7, 1938 v UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to improvements in electric float controls.

Float controls which have moving parts extending from inside to outside of a container have, so far as I am aware, required some sort of stuffing-box or packing, particularly if the parts are below the liquid level or if the container is at a pressure different from that of the atmosphere surrounding it. Where appreciable pressures are present the packing must be kept so tight as to interfere with a desirably free action of the control and even where such pressures are not experienced the packing required is not generally satisfactory. In the art of refrigeration, for example, especially where ammonia is used, the packing about movable parts must be carefully watched and great care exercised to see that it is kept tight. This, as before stated, makes the moving parts move stiliiy and a desired sensitivity in the control is not enjoyed.

It is an object of this invention to provide a control having a float member within a container and actuated by changes of liquid level therein and having means outside the container which are actuated by the movement of said member although there is no physical or mechanical connection between them. Thus all stuflingboxes and other forms of packing are eliminated. More specifically it is a feature of the invention to provide electric circuits whose characteristics are governed by the position of the float member to the end that difierent liquid levels efiect differ ent reactions in the circuits. Such a control is exceptionally sensitive.

The best modes in which I have contemplated applying the principles of my invention are shown in the accompanying drawings but these are to be taken as merely illustrative because it is intended that the patent shall cover by suit- 40 able expression in the appended claims whatever features of patentable novelty exist in the invention disclosed. a

. In'the drawings:

Figure 1 is an elevation partly in section showing how the level actuated means may be attached to a container and be actuated by the main body of the liquid;

Figure 2 is a diagrammatic showing of the elec- 50 trical circuits which may be associated with the level actuated means of Figure 1;

Figure 3 is another elevation, also partly in section, showing a modified form of float and means associated therewith; and

Figure 4 is a diagrammatic showing of the electrical circuits which are adapted to cooperate with the means shown in Figure 3.

Referring more particularly to the drawings, and especially to Figure 1, the wall I represents that of a container holding liquid 2 whose level is subject to change. Suitably attached to the container is what may be calleda base plate 3, having a hole 3a therethrough leading to the in- I terior of the container. Mounted on the base plate are supports 4, at the upper end of which is a top plate 5. Between the two plates is a tubular member 6, its ends being tightly sealed in circular grooves 312 and 5a of the respective plates. This member is made of non-magnetic material and preferably of material having low electric conductivity or high dielectric strength. It is arranged with respect to the hole 3a in the base plate so that a rod 8 may extend from a float 9 inside the container through the hole and to a metalcylinder Ill having high magnetic permeability. As the float moves upward and downward with changes of level of the liquid the member Ill, hereinafter called an armature, moves correspondingly within the tubular member.

Surrounding the latter near its upper end is a 25 coil of wire II connected to a source of alternating current. Outside of this coil are two U- shaped laminated magnetic bars l2 having high magnetic permeability and so disposed that their ends are separated by the tubular member. These bars together with the space through the middle portion of the coil (being the space containing the tubular member) constitute a path for the magnetic flux generated by the current flow in the coil. The latter and these bars, which serve as the fixed portion of the magnetic circuit and are hereinafter termed the fixed magnetic conductor, are adjustably mounted'on the supports] by a plate 1 and nuts la. When the float is at a relatively low level so that the armature I0 is below the coil and the fixed magnetic conductor l2, the electrical characteristics of the coil are unaffected by the armature, but when the latter moves upward to the position indicated in dotted outline, its high magnetic permeability cooperating with the fixed magnetic conductor, appreciably afiects the characteristics of the coil by changing the impedance. Thus it is that the moving parts within the space of the container (the interior of the tube 6 being treated as a part of such space) are able to affect an electrical agency outside of this space, which agency has no physical or mechanicalconnection with the moving parts inside the container.

To appreciate the effect of changing the characteristics of the coil I I reference is had to Figure 2 showing diagrammatically a preferred arrangement of circuits and electrical agencies. The wires i3, i4 of some suitable alternating current power line are separately connected to the primary windings i5a and iGa of a pair of duplicate transformers I 5 and i6 respectively. The secondary windings l5!) and I6?) of these transformers are connected together and form part of a circuit which comprises a wire I! connecting winding iBb with the coil ii already described and shown in Figure 1. This coil is connected by wire i8 with an identically similar coil i9 and the latter is in turn connected by wire 20 with the secondary winding I5b of the transformer i5. Associated with coil i9 is a fixed magnetic conductor 2i which is a duplicate of conductor i2, and within coil i9 is a fixed armature 22 which is a duplicate of armature Hi. It is clear that when armature i0 is in its upper position and occupies the same position relative to coil ii and the fixed magnetic conductor l2 that the fixed armature 22 bears to coil i9 and conductor 2i, the electrical characteristics of the two coils are the same. In other words, the value of the impedance of coil Ii is the same as the value of the impedance of coil i9.

Between the coils ii and IS, the wire i8 is connected to another wire 23 which leads to the energizing coil 24a of a relay 24, from which another wire 25 is connected midway between the secondary windings I51) and 16b. Since these windings have the same impedance and electromotive force, and since the coils ii and i9 have equal impedances when armature l0 occupies the same position with respect to coil Ii as the fixed armature 22 occupies with respect to coil l9, it follows that the current flow (alternating current flow) along wire i1, through coil Ii and wire i8, is the same as the flow through coil [9 and wire 20. Accordingly-the voltage drop or difference in potential along wire 23, through coil 24a and wire 25 is zero, and hence no current will flow along these last mentioned elements.

If, however, the level of liquid falls and armature in is withdrawn from within coil II, as shown in Figures 1 and 2, then the impedance of this coil is altered, being reduced because of the decrease in the inductive reactance of the coil. In other words, removal of the armature increases the reluctance to the flow of magnetic flux, thus decreasing the impedance of the coil. As a result more current can now flow along wire 11, through the coil H and along wire l8. Since the impedance of coil i9 has remained urichanged, substantially the same amount of current as before will flow through this coil and 'along wire 20, and the excess of current flow through coil ii will now pass along wire 23, through the relay coil 24a and thence along wire 25 to the transformer.

The energization of the coil 24a. by the flow of current just described effects movement of its armature 24b against the continuous tension of a spring 26. This relay 24 alone might be depended upon to control other agencies directly but is here shown as an intermediary element for closing an auxiliary circuit comprising the secondary winding 2'") of another transformer 21, whose primary winding 21a is connected to branch wires I30. and a leading from the power mains. This secondary winding 21b is connected by a wire 28 to a coil 29a of a second relay 29, which in turn is connected by a wire 30 to the switch of relay 24. Wire 3i returns from this switch to the secondarywinding 21b. Since an alternating current is always flowing through the primary winding 21a an induced current will flow along wire 28, through relay coil 29a, wire 30, and wire 3i whenever relay 24 is energized to close its switch.

This current flow energizes relay 23 and its armature 29b is moved against the force of spring 32 to close its switch. This is a part of a circuit comprising the wire I30, some electrically actuated element 33, a wire 34 leading thence to the switch of relay 29, and the wire l4a. When this circuit is made by the closing of the relay switch the current fiows through the element 33 and effects its operation as desired. As here shown. this element is a solenoid valve in a supply line 35 which may lead to container I, but it is clear that this is merely representative of any other equivalent element such as a compressor, indicator, etc. Here, since this valve controls the supply line to the container and since float 3 therein was assumed to fall and thus withdraw armature ill from within coil Ii, it follows that valve 33 will be opened to permit flow of liquid to container I to restore its level. Upon such restoration to a point where armature Hi again effects the coil ii so that it corresponds electrically with coil IS, the excess current flow along wire 23, through relay coil 24a and wire 25 will cease. Upon the consequent deenergization of relay 24, its controlled circuit will be broken and relay 29 in turn deenergized. Thus the electrical element 33 is affected in accordance with the shown in Figures 3 and 4. Here the armature i0 is itself a float and moves within a tubular member 6' held between two plates 3' and 5' by supporting bolts 4'. Each plate (they preferably are duplicates) has a hole (3a and 5b) connecting the interior of the tube with pipe fittings i' by which the interior of the tube may be placed in communication with a container much in the same manner as an ordinary gauge glass. Indeed, the tubular member 6' may be constructed of transparent material such as glass or quartz and perform the function of a gauge glass. The liquid in thec'ontainer finds its level in the tube and changes in this level move the float or armature upward or downward.

Mounted on the supports 4' is a coil i i' and a relatively fixed magnetic conductor i2 similar to those first described. This is held in position by a plate 'I' and nuts I'm at any selected elevation. Below, onthe supports 4 is another coil 36 and another relatively fixed magnetic conductor 31, these being likewise adjustably held by another plate '38 and nuts 38a. Thus there is provided separated electromagnetic fields which may be separately affected by the armature. As will presently appear, the amount or distance between these fields determines the delay or pause between one actuation and the other of a controlled electric element, such as the valve 33 shown in Figure 2.

Figure 4 shows diagrammatically the preferred arrangement of circuits to be associated with the coils ii and 3B. In this embodiment the wires i3 and M of the alternating current power line are connected to a transformer 15' having a single primary winding Wu and a single secondary winding i5b, although obviously the same arrangement of two transformers as is shown in Figure 2 might be employed. Wire I'I leading from one end of the secondary winding connects with coil II' and from this a wire I9 connects with a corresponding coil I9. This has a fixed magnetic conductor 2| and a fixed armature 22' like conductor I2 and armature II) respectively, so that when the latter is within coil II, the value of the impedance of coil II and coil I9 will be the same. The latter coil is in turn connected by wire 20' with the other end of the secondary winding l5'b.

An extension I'Ia of wire II also leads to coil 36 and another wire I8" connects this coil to still another coil' 39 having a fixed magnetic conductor 39 and a fixed armature 40 such that the value of the impedance of this coil 39 will be the same as that of the impedance of coil 36 when armature III is within the latter coil. Coil 38 is connected to wire 20' by the extension 2Ila.

The central portion of the secondary winding I5b is connected by a wire 25' and its branch 25'a with a coil 24'a of a relay 24'. This coil is also connected through the switch terminals of anotherrelay 4|, and by wire 23' with wire I8. The switch terminals-of relay 4| are normally maintained closed by a spring Ma and,

' assuming at the moment that this switch is closed,

it is evident that the action of the coils II and I9 and the relay 24 are similar to those of coils I I and I9 and relay 24 of Figure 2. When the armature I0 is withdrawn from coil I I, then current will flow along wire 23', coil 24a and wire 25, (assuming the switch of relay H to be closed) and relay 24' will be energized to close its switch. The latter is part of a circuit comprising a wire 42 leading from wire II, the

switch of relay 24', a wire 43 leading thence to a coil 44a of a double switch relay 44, and wire 45 running backto the wire 20. Accordingly, as the switch of relay 24' is closed, current will flow in the last mentioned circuit and energize the coil 44a. This will cause terminal 46 to disengage from another terminal 41 and move terminal 43 into contact with the terminal of wire I4'a. The main circuit is thus established along wires I3'a and I4'a (plus its extension I4'a connected to terminal 48) through an electric element 33, (not shown in Figure 4) which may be a solenoid valve as indicated in Figure 2. This valve is held open while the armature III is outof coil II and within coil 36. While this condition prevails there will be equal current flow through

coils

36 and 38 since the value of the impedance of each coil is the same. Consequently no flow will occur along a wire 49 which leads off from wire I8" tothe coil 4") of relay 4I. This coil is also connected by wire 50 with the terminal 46, previously mentioned as being out of engage ment with another terminal '41.

But now assume the liquid level changes so that armature I0 moves out of coil 36. This will afiect the impedance of the coil and more current will flow along wire I1 ("'11) and the coil,

and wire I8". This would be expected to cause current flow along wire 49 but it will be recalled current flow along wire 23.

the coil 241a of relay 24\is dcenergized and its switch opened under the pull of spring 26. This,

of course, breaks the circuit through coil 44a and thus allows terminal 48 to separate from wire I4'a thus opening the circuit controlling the electrical element 33. At the same time terminal 46 moves to engage terminal 41 and completes a circuit for current flow alongwire 49, coil 4Ib, wire 50, and thence along a branch 25'b connecting terminal 41 with the wire 2!.

Completion of the last mentioned circuit and consequent flow of current through coil 4Ib causes the switch of relay 4I to open against the pull of spring a. This, of course, breaks the circuit between wire I9 and the transformer along wire 23 etc., although, as just described, there is at the moment no flow along wire 23' because armature III is within coil II. The purpose of thus opening the switch of relay H is to prevent any change in the position of the terminals of relay switch 44 until armature I3 is again moved within coil 39. That is to say, when the armature moves out of coil II a flow of current would occur along wire 23 if the switch of relay H were not open. Since it is held open by the current flow along wire 49, no

current can flow along wire 23' until the armature moves into coil 36 and establishes conditions which stop the flow along wire 49. As this takes place, coil 4": is deenergized, the switch of relay 4| is closed and then current will flow,

along wire 23' to energize coil 24a. As previously described, this brings about the opening of

terminals

46, 41 and closure of terminal 43 with the wire I4'a, and the consequent actuation of the electrical element 33.

Thus the modification of the invention shown in Figures 3 and 4 enables a predetermined delay in the control of the element 33, and this delay may be determined by the relative positions of the coils II and 36 on the support rods 4'.

I claim:

1. Electric float control apparatus for restoring the level of liquid in a container comprising a transformer connected to a source of alternating current; a pair of circuits connected to the secondary winding of said transformer; a pair of coils in each of said pairs of circuits; one coil in each of said pairs of, circuits having associated therewith a fixed magnetic conductor arranged externally of said coil and a fixed armature arranged internally of said coil; the other coil in each of said pairs of circuits having a corresponding fixed magnetic conductor arranged externally thereof; a fixed tubular member extending through each of the last mentioned coils,

having an open connection with the container; an armature movable within said tubular member in response to changes of the liquid level in the container, and adapted when positioned in the path of magnetic flux of either of the last mentioned coils to increase the flow of said flux and thereby increase the impedance and correspondingly reduce the current flow through the coil surrounding said movable armature; a second pair of circuits, one of which is connected between one of the first mentioned pair of circuits and the secondary winding, and the other of which is connected between the other of the first mentioned pair of circuits and the secondary winding; and means associated with said second pair of circuits for controlling the admission of liquid to the container; the said apparatus being so organized that when the liquid is at a desired level the movable armature is positioned in the magnetic path of one of the last mentioned coils with respect to which it is movable whereby admission of liquid to the container is cut oil, and when the liquid falls to a predetermined lower level the movable armature is positioned in the magnetic path of the other of the last mentioned coils with respect to which it is movable whereby admission of liquid to the container occurs to restore the desired level; and said apparatus being further organized so that the control determined by the presence of the movable armature within the magnetic path of one of the coils with respect to which it is movable continues until the movable armature has moved within the magnetic path of the other of the coils with respect to which it is movable.

2. Electric float control apparatus for restoring the level of liquid in a container comprising a transformer connected to a source of alternating electric current; a connection between the secondary winding of said transformer and a coil; said coil; a connection between said coil and a relay; said relay; a connection between said relay and said secondary winding at a point remote from the first mentioned connection; means actuated by a predetermined current fiow through said relay to effect admission of liquid to said container; a fixed magnetic conductor arranged externally of said coil having high magnetic permeability; a fixed tubular member, extending through said coil and in open connection with the container, having low magnetic permeability and a high electrical resistance whereby the fiow of magnetic flux through the fixed magnetic conductor is retarded and the formation of eddy currents is rendered negligible; and an armature of high magnetic permeability movable in said tubular member in response to changes of liquid level in the container; the apparatus being so organized that when the liquid is at the desired level the armature is withinthe said coil and coacts with said fixed magnetic conductor to increase the flow of magnetic fiux and. the impedance of the coil with consequent reduction of the current flow whereby the current fiow through said relay is below the said predetermined flow, and when the liquid level falls the armature is removed from said coil thereby efiecting a decrease oi flow of magnetic flux and the impedance of the coil with consequent increase of current fiow to provide the predetermined flo through said relay.

3. Electric float control apparatus for restoring the level of liquid in a container comprising a transformer connected to a source of alternating electric current; a circuit connected to the secondary winding of said transformer; a coil in said circuit; a fixed magnetic conductor arranged externally of said coil having high magnetic permeability; a fixed tubular member extending through said coil and in open connection with the container, having low magnetic permeability and high electrical resistance whereby the fiow of magnetic flux through the flxed magnetic conductor is retarded and the formation of eddy currents is rendered negligible; an armature of high magnetic permeability movable within said tubular member in response to changes of liquid level in the container; the said armature being positioned within said coil when the liquid is at the desired level to increase the fiow of magnetic flux through the fixed magnetic conductor and the impedance of the coil with corresponding reduction of current flow in said circuit, and being withdrawn from said coil when the liquid falls below the desired level to eflect reduction of flow of magnetic flux through the fixed magnetic conductor and the impedance oi the coil with consequent increase of current flow in said circuit; and means associated with said circuit and responsive to changes in the current flow therethrough for controlling the admission of liquid to the container so that upon fall of the liquid level and consequent withdrawal of the armature from said coil said responsive means are actuated to admit liquid to the container and restore the level.

4. A circuit for electric float control apparatus having an armature member of high magnetic permeability movable, within a fixed tubular member of low magnetic permeability and high electrical resistance, in response to changes of level of a liquid; said circuit comprising a transformer connected to a source of alternating electric current; a lead from the secondary winding of said tranformer to a coil surrounding the said fixed tubular member and having a fixed magnetic conductor of high magnetic permeability arranged externally of the coil; a lead from said coil to another coil having electrical characteristics corresponding to the first mentioned coil with a fixed armature member within said other coil and a second fixed magnetic conductor arranged externally of said other coil both with electro-magnetic characteristics corresponding respectively to the movable armature member and to the first mentioned fixed magnetic conductor; a lead from said other coil to the said winding of the transformer; a lead from the lead intermediate of said coils to a relay; a lead from said relay to the secondary winding intermediately of the other said leads connected thereto; and means actuated by said relay for effecting a change in the level of the liquid; the de-energization of said relay being efiected when the movable armature member is moved within the tubular member to a position with respect to the first mentioned coil corresponding to the position of the fixed armature member with respect to the second mentioned coil, and the energization of said relay being efiected when the movable armature member is moved to without the magnetic field of the first mentioned coil. JACOB LEE TURNER.