US2734678A

US2734678A - edwards

Info

Publication number: US2734678A
Authority: US
Publication date: 1956-02-14
Anticipated expiration: 1973-02-14

Description

1956 T. H. EDWARDS MAGNETIC CONTROL DEVICE FOR PUMPS 2 Sheets-Sheet l Filed Feb. 23, 1954 INVEN TOR. Thomas H Edwards A T TORNE Y MAGNETIC CONTROL DEVICE FOR PUMPS 2 Sheets-Sheet 2 INVEN TOR. Thomas H Edwards Filed Feb. 23, 1954 A T TORNE Y United States PatentO MAGNETIC CONTROL DEVICE FoR PUMPS Thomas H. Edwards, Richlaml, WaslL, assignor to the United States of America as represented by the United States Atomic Energy Commission Application February 23, 1954, Serial No. 412,129

4 Claims. (Cl. 230-83) The present invention relates to a magnetic-control device and more particularly to the use of such a device for controlling a pump.

In the transfer and manipulation of certain fluid substances the slightest contamination of the working fluid from a pump lubricant is undesirable. When the working fluid is highly toxic to personnel or very scarce, care must be taken to prevent accidental loss or escape of even minute quantities of such working fluid during handling. A positive displacement mercury pump meets these requirements, but creates the necessity for a device that is responsive to the rise and fall of the mercury level in a working chamber of the pump.

An object of the present invention is to provide a magnetic-control device that will automatically regulate a pump of the above type.

My invention may be used in a variety of fluid transfer applications, a favorite one of which is described below in the drawings and specification.

Inthe drawings:

Fig. l is a diagrammatic view of the magnetic-control device of the present invention and a pump to which the device is applied;

Fig. 2 is a vertical sectional view, partly in elevation,

of the magnetic-control device and adjacent portions of the,

pump, to which it is applied;

Fig. 3 is a horizontal sectional view taken on the line 33 of Fig. 2; and a Fig. 4 is a vertical sectional view taken on the line 4-4 of Fig. 3 and showing a mercury switch that, may be used in this magnetic-control device.

The magnetic-control device of the present invention, which will be described presently, may be applied to a mercury pump of the positive-displacement type. As

shown in Fig. 1, this pump 10 comprises a working chamber 11, a mercury sump 12, a connection 12a between the working chamber 11 and the sump 12, an intake line 13, an exhaust line 14, an intake check valve 15, a discharge check valve 16, and means for increasing and decreasing the air pressure in the space above the mercury in, the sump 12. Such means may comprise a valve 18, a pressure pump 19, a vacuum pump 20, and a pipe 21 connecting the air space with the valve 18, a pipe 22 connecting the pressure pump 19 with the valve 18, and a third pipe 23 connecting the vacuum pump 20 to the valve 18. l

The intake cycle of the pump is initiated when the air pressure in the air space above the mercury in the sump 12 is reduced by connection of the vacuum pump 20 with will be closed to prevent the entrance of working fluid into the working chamber 11. Rise of the mercury in the sump 12 to a predetermined level will cause means to be described presently to shift the valve 18 to a position in which it connects the pressure pump 19 with the space above the mercury in the sump. The pressure in this space will be increased, the mercury in the sump will fall, and the level of mercury in the working chamber 11 will rise. As the mercury rises in the working chamber 11 past the connection of the intake line 13, the mercury traps and compresses the working fluid in the upper part of the working chamber 11, and with continued rise it forces the trapped working fluid into the discharge pipe 14, unseats the valve float 31, and finally forces the working fluid past the discharge check valve 16; continued as to prevent the mercury from passing through them.

After the rising mercury has forced the entrapped parcel of working fluid out of the working chamber and past the discharge check valve 16, the exhaust phase of the pumping cycle is completed. Thereupon, the intake phase of the pumping cycle will be initiated by shifting the valve 18 to connect the pipe 21 to the vacuum pump 20 which reduces the air pressure over the mercury in the sump 12 whereupon the mercury level in the intake and

discharge branches

13 and 14 above the working chamber 11 falls. By reason of continued decrease of air pressure in the space over the mercury in the sump 12 the mercury in the working chamber will fall at least as low as the connection of the intake line 13.

The present invention isa control device responsive to the level of the mercury within the discharge check valve 16, which at the end of the exhaust phase of the pumping cycle causes a circuit described below to be energized, thereby shifting the valve 18 from a position involving connection of the pressure pump 19 to the air space above .the mercury in the sump v12 to a position involving con- 4 extends at least generally in the vertical direction, which is the direction in which the float 31 moves in a casing 31a, also forming part of the valve 16. Both the float 31 and the casing 31a are made of a material of low magnetic permeability. The float 31 is made of upper and

lower sections

32 and 33, having threaded connection with one another. The magnet30 rests on the lower member 32,

and the upper member 33 extends into the lower member into immediate proximity to the magnet 30. Thus the magnet is held against substantial movement withv rerespectively against an upper conical surface 34 or a lower conical surface 35 of the casing 31a, it will seat v snugly and form a tight seal which on the exhaust phase of the pump cycle will prevent the flow of mercury above the check valve 16, and in the intake phase of the pump cycle will prevent the return of working fluid back through the discharge valve 16.

In addition to the casing 31a and the float 31, the discharge check valve 16 includes flanges 36 and 37 secured to one another by screws 38, the flange 36 being secured to the casing 31a" and the flange 37 being secured to a discharge line 39 extending beyond the discharge check valve 16.

A switch 40, which includes a movable electrode 41 and a small permanent magnet 42 attached thereto, is mounted and housed in an envelope 42a of nonconducting material such as glass. The envelope and the switch are supported by a strap 43 which has one end wrapped around the envelope and extends through a lug 44' which supports it. The lug is adjustably secured by a screw 45 to a vertical bracket 46 which has a horizontal upper end 46a secured to the flange 37. The end of the strap 43 opposite that wrapped around the switch envelope 42a is bifurcated as indicated at 47 and has secured to it pins 43 which partially penetrate opposite Walls of a short sleeve 49 carrying a generally horizontal permanent bar magnet 50. The sleeve 49 pivots on the pins 48, thereby providing a pivot for the magnet 56. The magnet has

poles

53 and 54 at its ends. An electromagnet 56 is mounted on one end of a bracket 57, the other end of which is secured to the bracket 46 between the latter and the lug 44. The screw 45 extends through a vertical slot 58 formed in the vertical bracket 46, and vertical adjustment of the switch 40, the pivoted magnet 59, and the electromagnet 56 with respect to the magnet 30 in the float 31 is achieved by loosening of the screw 45 and shifting of the screw and the associated parts along the slot 53. The envelope 42a may be shifted along the end of the strap 43 wrapped around it, and thereby proper positioning of the magnet 42 of the switch 40 in the envelope 42a with respect to the pivoted magnet 51) may be achieved. The strap 43, the lug 44, the screws 45, and the

brackets

46 and 57 are formed of materials of low magnetic permeability.

Referring now to Fig. 3, the pivoted magnet 50 may assume one of two limiting positions. At the end of the pump exhaust cycle the float member 31 will be found inits uppermost position, bringing the lower pole of the magnet 30 near the pole 53 on the magnet 50, which pole is opposed to said lower pole. Consequently, a repulsive force is set up which moves the magnet 50 to the dotted position of Fig. 3 in which a pole 54 thereof is adjacent the switch 40. The resultant force of attraction between the pole 54 and the switch magnet 42 causes the switch 40 to open.

The electromagnet 56 has one end secured to the bracket 57 and the other end adjacent the pole 53 of pivoted magnet 50 in its dotted-line position and is wound: so as when energized to exert a magnetic repulsive force against the pole 53, thereby moving the magnet 50 to the fullline position. When this has happened, it is presumed, as will be explained later, the float 31 and the magnet 30 will be in the lowermost position of Fig. 2, in which the upper pole of magnet 30 will attract the pole S3 of magnet 50, thus holding the magnet 50 in the full-line position.

The contact switch electrode 41 is spring mounted so that when the magnetic force of magnet 50 is removed from the immediate vicinity of the switch, the electrode 41 returns to its closed switch position, shown in Fig. 4' in solid lines.

Fig. 4 shows the details of the mercury switch 40. The case 42a holds a small pool of mercury 61 in its lower end. A stationary electrode 62 extends from one lead 63 into the mercury pool. The electrode 41, connected to a lead 64, is movable and spring-biased so that it is in. contact with the mercury pool 61 when the pole-54ofthe magnet 50 is not adjacent the switch magnet 42. When the magnet 50 is pivoted so as to bring the pole 54 adjacent the switch magnet 42, the electrode 41 is pulledout of the mercury pool 61 to the dotted-line position of Fig. 4, thus opening the switch 49-.

The intake check valve 15 may consist of a hollow cylindrical shell 65 and a float member 66 within the case. The float member has longitudinal external ribs 66a, which hold the float member against lateral move ment in the shell 65 and yet permit flow of working fluid past the fioat member when in the position shown on Fig. 2. The upper end of the float member 66 is tapered as shown at 67 so as to seat snugly against an upper surface 68 of the valve shell 65 and thereby prevent flow of mercury above the valve 15 when the float member is lifted by the upward flow of mercury to the valve during the exhaust phase of the pump cycle. The float member 66 is shaped on its lower end so that a seal is not formed when the float member rests on the lower interior surface 69 of the valve shell; accordingly working fluid will diffuse downward through the check valve 15 during the intake phase of the pump cycle.

The valve 18 is controlled by a solenoid 70 in such a way as to connect the pressure pump 19 with the air space in the sump 12 when the solenoid is not energized and to connect the vacuum pump 20 with said space when the solenoid is energized. The solenoid 70 is energized when it is connected by a switch 71 with an A. C. power supply; Switch 71 is normally closed and is opened by energization of a coil 72a.

A selector switch 73 permits energization of the coil 72a manually through a contact 74 or automatically through a contact 75, leads 63 and 64, switch 40, mercury in sump 12, and intermediate and low contacts 77 and 78 in the sump, and a lead 79 from the low contact.

Interruptions at the proper phase in the pumping cycle when in automatic operation are obtained by periodic energizing of the electromagnet 56 through a rectifier 80, which is connected with the secondary of a transformer 81 on one side through a lead 82 and on the other side through a lead 83, a contact 84 at a high level in the sump 12, the mercury in the sump, the low level contact 78, and the lead 79.

The description of operation will now be completed if we start with the part of the cycle at which the mercury is at some low point in the working chamber 11 below the connection of the intake line 13' therewith and is at some high point in the sump 12 such as the contact 84, to which it has been brought by the vacuum pump 20, a circuit is closed through the contact 84, the mercury in the sump '12, contact 78, and rectifier 80, with the secondary of transformer 81. Since electromagnet 56 is connected with the rectifier 80, the electromagnet 56 is energized'and swings the magnet 50 to its full-line position of Figs. 1 and 3', in which pole 54 is away from magnet 42 of switch 40. This allows the switch 40 to close, and a circuit is closed through coil 72a, which opens switch 71 and deenergizes solenoid 70, which shifts valve 18 to a position in which it connects the air space over the mercury in the sump 12 with the pressure pump 19.

Air under pressure will then be forced from the pump 19 through pipe 22, valve 18, and pipe 21 into the air space above the mercury in the sump 12, causing the mercury to fall in the sump 12, and to rise in the working chamber 11. The rising mercury in the working chamber 11 will displace any working fluid in the chamber 11 forcing it through the discharge'pipe 14 and the discharge check valve 16. The'rising mercury will also float the check valve floats 31 and 66, preventing the mercury from go'- ing above these valves in their respective branches of the pump circuit.

When the float 31 under the action of the rising mercury lifts: the magnet 30 to a position in which the lower pole thereof lies opposite the pole 53 of the pivoted magnet 50,

the repulsive force" set upbetween the magnets will swingthe magnet 50 to its broken-line position in which it again attracts the switch magnet 42, causing it to move and there by pull the contact 41 out of the mercury pool 61. This action will close the switch 71, energize the solenoid 70 and cause the valve 18 to connect the vacuum pump 20 with the air space over the mercury in the sump 12. The pressure in this air space will fall rapidly, causing the mercury level in the sump 12 to rise and that in the working chamber 11 to fall.

When the mercury in the working chamber has fallen below the level of the connection of the intake line 13 with the working chamber, working fluid will diffuse through the intake check valve 15 and the intake pipe 13 into the chamber 11.

The rising mercury in the sump 12 will eventually reach the contact 84 and close the circuit energizing the electromagnet 56. Thereupon the pivotally mounted magnet 50 will be rotated back into its solid-line position. The switch 40 will close and the exhaust phase of the pump cycle will again be initiated.

The intermediate contact 77 in the sump 12 serves, in the event the control mechanism fails to terminate the exhaust phase of the pump cycle in proper time, as a safety device. Fall of the mercury level in the sump 12 below the contact 77 will open the circuit that energizes the coil 72a and connects contact 77 with the coil 72a through leads 64 and 69, contact 40, lead 63 and selector switch 73, therewith deenergizing the solenoid 70 and permitting the valve 18 to connect the vacuum pump 20 to the space over the mercury in the sump and thereby initiating the intake phase of the pump cycle. The solenoid 70 is energized when the switch 71 is closed and is de-energized when the switch 71 is open; however, the switch 71 is normally open and is closed only by repulsive magnetic force from the coil 72a. Thus solenoid 70 is de-energized when the circuit which energizes coil 72a is opened.

It will be understood that the present disclosure is susceptible of various changes without a departure from the spirit of the invention, and that the invention is to be lim ited only by the scope of the appended claims.

What is claimed is:

1. Apparatus for oscillating a liquid level in a container between two limits, comprising a float member having therein a vertical permanent magnet, means using materials of low magnetic permeability for guiding the vertical motion of the float, a pivoted permanent magnet adjacent to the upper end of the vertical magnet when said float is at its lowest most position, said pivoted magnet having a first position involving proximity thereof and the vertical magnet permitted by attraction between the pivoted magnet and the upper end of the vertical magnet and a second position involving proximity of the pivoted magnet and the vertical magnet produced by repulsion between the pivoted magnet and the lower end of the vertical magnet,

an electrically actuated mechanical means for adjusting the liquid level, said mechanical means having a control circuit and a normally closed switch in series connection with the control circuit, the normally closed switch opened in response to proximity of the pivoted magnet in its second position, the mechanical means adapted for raising the liquid level in response to closing of said switch and for lowering the liquid level in response to opening thereof, and an electromagnet adjacent to the pivoted magnet and adapted on actuation to rotate said pivoted magnet into said first position thereby closing said switch, means responsive to fall of the liquid to a certain level to actuate the electromagnet.

2. Apparatus for oscillating a liquid level in a container between two limits, comprising a float member having therein a vertically oriented bar magnet, means using material of low magnetic permeability for guiding the vertical motion of the float member, a second bar magnet pivotally mounted adjacent to the upper end of the first bar magnet contained within the float when said float is at its lowest position, said pivotally mounted magnet having a first pivotal position permitted by attraction between the same and the upper end of the vertically oriented magnet and a second pivotal position produced by repulsion between the pivotally mounted magnet and the lower end of first magnet, a solenoid transfer valve circuit, means for. closing said solenoid transfer valve circuit and opening said solenoid circuit in response to the two pivotal positions respectively of the second magnet, means whereby the level of liquid is raised in response to closing said solenoid circuit, and means whereby level of liquid is lowered in response to opening said solenoid circuit, an electromagnet adjacent to the pivotally mounted magnet in its second pivotal position and adapted on actuation to rotate the same into the first pivotal position whereby the solenoid circuit is closed, said electromagnet being energized by a circuit which closes in response to fall of the liquid below a predetermined level, whereupon the liquid is caused to rise and continues to rise until the solenoid circuit is opened when the lower end of the vertically oriented magnet repulses the pivotally mounted magnet and thereby initiates the means which lowers the liquid to the said predetermined level, whereupon the cycle is again repeated 3. In an apparatus for producing a vacuum, comprising a tank having upper and lower ends, a line leading from the upper end of the tank, a sump, a connection between the sump and the lower end of the tank, there being a body of mercury in the tank, connection, and sump, the said vacuum being produced by alternately lowering and raising the body of mercury by pressure exerted on the surface of the portion of the body of mercury in the sump, an electromagnet energized in response to rise of the mercury in the sump to a given level, and means including a magnetic switch increasing the pressure above the level of the mercury in the sump to lower said level and raise the level of the body of mercury; the combination therewith, of a permanent magnet pivoted for movement about a vertical axis between a first position in which a first pole of the pivoted magnet is adjacent the electromagnet and a second pole is adjacent the magnetic switch so as to hold the same open and thereby prevent the pressure over the mercury in the sump from being increased and a second position in which the said first pole is spaced from the electromagnet and the said second pole is spaced from the magnetic switch, the shift from the first position to the second position being produced by repulsion between the electromagnet when energized and the said first pole, the movement of the said second pole away from the magnetic switch causing it to close for increasing the pressure above the mercury in the sump, a vertical permanent magnet located adjacent one pole of the pivoted permanent magnet in its second position and having its lower pole like the said one pole of the pivoted permanent magnet, a float member carrying the vertical permanent magnet and positioned in the line so as to be capable of floating in the portion of the body of mercury rising from the tank into the line, whereby the vertical magnet goes up and down with rise and fall of the body of mercury, means for limiting upward movement of the vertical magnet to a position of adjacency of the lower pole to the said one pole of the pivoted magnet when in the second position for shifting the same to the first position to open the magnetic switch and decrease the pressure on the mercury in the sump, and means for limiting downward movement of the vertical magnet to position of adjacency of the upper pole thereof to the said one pole of the pivoted magnet in its second position so as to enable the vertical magnet to hold the pivoted magnet in its second position.

4. In an apparatus for producing a vacuum, comprising a tank having upper and lower ends, a line leading from the upper end of the tank, a sump, a connection between the sump and the lower end of the tank, there being a body of mercury in the tank, connection, and sump, the said vacuum being produced by alternately lowering and raising the body of mercury by pressure exerted on the surface of the portionof the' body of mercury in the sump, an electromagnet energized in. response to rise of the mercury in the sump to a given level, and means including a magnetic; switch for changing the pressure above the level of the mercury in the sump to lower said level and to raise said level of the body of mercury; the combination therewith, of a permanent magnet pivoted about a vertical axis which permits movement of the magnet between a first position in which a first pole of the pivoted magnet is adjacent the electromagnet and a second pole is adjacent the magnetic switch so as to hold the same open and a second position in which the said first pole is spaced from the electromagnet and the said second pole is spaced from the magnetic switch, the shift from the first position to the second position being produced by repulsion between the electromagnet when energized and the said first pole, the movement of the said second pole away from the magnetic switch causing it to close and thereby actuate means for increasing the pressure above the mercury in the sump, a float member adapted to fioat on the surface of the body of mercury rising from the tankinto the line, a vertical permanent magnet carried thereby so as to go up and down with the rise and fall of the body of mercury in the line and having its lower pole of the same polarity as the first pole of the pivoted magnet, means for limiting upward movement of the vertical magnet to a position of adjacency of its lower pole to the said first pole of the pivoted magnet when said pivoted magnet is in the second position, repulsion between these poles during said adjacency returning the pivoted magnet to its first position and making the first said pole thereof open the magnetic switch and reduce the pressure on the mercury in the sump, and means for limiting downward movement of the vertical magnet to a position of adjacency of the upper pole thereof to the said first pole of the pivoted magnet in its second position, attraction between these poles during said adjacency holding the pivoted magnet in its second position.

No references cited.