US2093582A - Temperature regulator - Google Patents

Description

Sept'Zl, 1937. F. F. UEHLING 2,093,582

TEMPERATURE REGULATOR Filed March 9, 1935 j f3 .gege-2155;"

4g 373/6 4-7 C 46 B 5 30 44 roi 3a 37 35 48\46 43-a I ze 36" 34 3/ j Patented Sept. 21, v1937 UNITED STATES PATENT OFFICE TEMPERATURE REGULATOR Fritz Frederick Uehling, Passaic, N. J.

Application March 9, 1935, Serial No. 10,343

' 20 Claims. (Cl. F15-320) This invention relates to means for regulating high temperatures in connection with which temperatures a thermo-couple is utilized to provide an velectro-motive force, the variations in which force actuate the controlling elements. More particularly the invention provides a novel form of galvanometer or thermo-couple actuated means which in combination with novel circuits and relays increases or decreases the heat input to a furnace or any other chamber or medium, the temperature of which is to be regulated.

Although the following description and accompanying illustrations cover a particular application of the invention-for regulating temperature, it is obvious from the disclosures that the invention may be utilized to regulate any variable so long as the variable produces an electro-motive force which varies in proportions to changes in the variable regulated.

Figure 1 is a diagrammatic illustration partly -in cross-section, which shows a novel form' of galvanometer with its relays and all the important elements of the invention; Figure 2 is a cross-section through the galvanometer; Figure '3 is an, 5 other view of the relays with the positions of their -switches opposite to that illustrated in Figure 1.

The moving element of the galvanometer consists of a pendulum I2, Figure 1, which is pivoted at IBand I1, Figure 2. To the lower end of the pendulum and at right angles to its axis is fastened a permanent magnet 5 as illustrated. The pendulum which includes the permanent magnet is supported by and pivoted on two cross pieces Il and I5 which are fastened at the upper end of a frame I3 from which they are electrically insulated. Two solenoids 3 and l are fastened to the lower end of the frame, one on each side of the permanent `magnet as illustrated, with their elevation such that their axes coincide with the yaxis of the magnet. The solenoids are connected in series, and are wound so that when energized by an electric ow in one direction, the pendulum which includes'the permanent magnet will be forced to the right and when energized by an electric iiow in the opposite direction, the pendulum will be forced to the left. The advantage of this novel form of galvancmeter lies in the fact that the actuating coils are stationary and. may therefore be wound for any number of amwhile the sensitivity may be increased almost lnpere turns regardless of the quantity or weight` illustrated by dotted lines to distinguish it from 'the other circuits. 'I'his circuit starts at the couple 2|, thence through wire 22 to solenoid A, from solenoid 4 through wire I9 to solenoid from solenoid 3 through wire 20, to an adjustable potentiometer I4-18, and thence through wire i3'back to the couple. The purpose of the potentiometer I4-'I8 will be presently described.

The magnet 5,- Figure 1, is provided with a silver contact piece 8 at one end, and asimilar contact piece 9 at its opposite end. Electrical contact is respectively established between these contact pieces and contact screws B or 'l depending upon whether the pendulum is deected to the left or to the right. The contact screws are electrically insulated by means of insulation pieces I land l0 respectively, and are adjustable so that the gap between the screws and their 'respective contact pieces can be made as small as desired. Electric contact thus established between the pendulum and one or the other of the screws 6 and I closes the proper circuits to actuate the relays A, B, and C in the manner and for the purpose to be presently stated.

The relay or coil A when energized actuates an armature 55 which is pivoted at 51. When the coil is deenergized, the armature is held in its normal position as illustrated, by a contact spring I2 through an insulation piece 58 which communicates with an extension arm 56. A contact blade Il is so placed with respect to the contact spring l2 that when the coil A is energized, electric contact will be established between them. The contact lspring 42 and the contact blade II will hereinafter be referred to as switch lI-u, said switch being closed when the coil A is energized and open when said coil is deenergized.

Similarly the relay or coil C when energized actuates an armature 5I which is pivoted at 53. When the coil C is deenergizedthe armatureisheld in its normal position as illustrated, by means of a contact spring I5 through an insulation piece 54 which communicates with an extension arm Cil 52. A contact blade 41 is so placed with respect to the contact spring 46 that when the coil C is deenergized, electrical contact will be established between them. The contact spring 46 and the contact blade 41 will hereinafter be referred to as switch 46-41, said switch being open when the coil C is energized and closed when said coil is deenergized.

'Ihe relay or coil B when energized actuates an armature 59 which is pivoted at 6I. This armature communicates with a number of switches through its arm 60 and insulation' pieces 62, 63 and 64. When the coil B is deenergized the armature 59 yis held in its normal position as illustrated in Figure l, by means of three contact springs 49, 31 and 10. Contact blades 29, 38 and 69 are so placed with respect to contact springs 49, 31 and 16 'respectively that when the coil B is energized, electric contact will be established between 49 and 29, 31 and 38, and'between 10 and 69. Another contact blade 3D is provided which makes electric contact with blade 29 when the coil B is deenergized and with which it breaks contact when said coil is energized The contact blade 29 is designed as illustrated to permit making contact between 49 and 29 before contact between 29 and 30 is broken. The contact spring 49 and the contact blade 29, the contact blade 29 and the contact blade 39, the 4contact spring 31 and the contact blade 38, and the contact spring '1B and the contact blade 69, will hereinafter be referred to as switches 29-49,v 29-30, 31-38, and 69-10 respectively. Switches 29-49, 31-38 and 69-10 will thus be open and switch 29--30 closed when the coil B is deenergized as illustrated in Figure 1, and when the coil B is energized, switches 29-49, 31-38 and 69-10 will be closed and switch 29-30 open'as illustrated in Figure 3. The coils A, B and C and the described switches are supported by an insulation piece 65 which insulates the terminals of the coils as well as all of the elements of the switches as illustrated.

The circuit which is closed by electrical contact between the pendulum and contact screw 1, starts at battery 26, thence through wires 25 and 23 to solenoid 3, from solenoid 3 through wire I9 to solenoid 4, from solenoid 4 through wires 24 and 33 to the pendulum support I4, and from the pendulum support through a flexible connection I8 to the pendulum arm I2. When the pendulum is deflected to the right so that contact is established between the contact piece 9 and the screw 1, the circuit will be closed and continues throughl wire 32 to the coil A, and thence through wire 3|, switch 29-30 and Wires 28 and 21 back to the battery, the switch 29-30 being closed when the coil B is deenergized as illustrated in Figure 1. Similarly the circuit which is closed by electrical contact between the pendulum and the contact screw 6, starts at battery 12, thence through wires 25 and 23 to solenoid 3, from solenoid 3 through wire I9 to solenoid 4, from solenoid 4 through wires 24 and 33 to the pendulum support I4, and from the support through the flexible connection I8 to the pendulum arm I2. When the pendulum is deflected to the left so that contact is established between the Acontact piece 8 and the screw 6, the circuit will be closed and continues through wire 39 to the switch 31-38, and when the switch 31-38 is closed by the coil B, as illustrated inFigure 3, the circuit continues through wire 36, coil C and wires 35 and 34 back lto the battery.

There are two circuits which include the coil B, the rst of which includes the switch 30-29, and the second or holding circuit which includes switch 29-49. The rst of said circuits starts at battery 12, thence through wires 34 and 48 to switch 46-41, from said switch through wire 45 to the coil B, from the coil B through wires 44 and 43 to switch 4I-'42 and from the switch 4I-42 through wires 40 and 21, and thence through battery 26 back to battery 12. Similarly the second or holding circuit through the coil B starts at battery 12, thence through wires 34 and 48 to switch 46-41, from said switch through wire to the coil B, from coil B through wires 44 and 50 to switch 29-49, which switch is closed when the coil B is energized as illustrated in Figure 3, and from switch 29-49 through wires 28, 21 and battery 26 back to battery 12. It will be noted that both of the circuits which include the coil B include the batteries 26 and 12 in series. 4

v Let us now assume that the current iiowing through the thermo-couple circuit is of the proper polarity and just sufcient to cause a very delicate contact between the contact piece 9 and the contact screw 1. As previously stated, the circuit which is closed by this contact includes the coil A, the switch 29-30, the battery 26 and the solenoids 3 and 4. 'I'he delicate pressure which the contact piece 9 exerts against the screw 1 by virtue of the thermo-couple circuit is however s'o small that the contact resistance willy` not permit suicient current to ow through the circuit from battery 26 to actuate the armature 55. The battery 26 is however of the proper polarity so that the current which does iiow through the circuit will cause the solenoids to react with the permanent magnet 5 to force the contact piece 9 tighter against the screw 1. The increased pressure between the contact piece 9 and the screw 1 will obviously decrease the contact resistance thereby increasing the flow through the circuit which in turn still further increases the pressure between the contact'piece 9 and the screw 1 to again increase the flow. It

therefore follows that regardless of the delicacy of the initial pressure of the contact piece 9 against the contact screw 1 as caused by the thermo-couple circuit, said pressure will build up almost instantaneously until suicient current ows from the battery 26 to actuate the armature 55. The armature will thus react with the coil A to close the switch 4I-42 immediately after the small ow through the thermo-couple circuit causes the initial contact between the contact piece 9 and the contact screw 1. The closing of the switch 4I-42 will close the first circuit (already traced) through the coil B which coil when energized, reacts with the armature 59, Figure 3, to close the switches 29-49, 31-38 and 69-16, and to open the switch 29-36. The switch 29--30 thus opens the lcircuit through the coil A which circuitwas initially closed by contact between 1 and 9, thereby permitting the switch 4I-42 to open, and simultaneously closing the switch 29--49 to close the second circuit (already traced) through the coil B. This second or holding circuit through the coil B maintains the switches in the position illustrated in Figure 3. The circuit which includes the battery 26, the switch 29-39, the coil A and the solenoids 3 and 4 is now open through the switch 29-36 thus again permitting the pendulum to be influenced solely by the current owing through the thermothermo-couple circuit has changed so that the pendulum is deflected to the left just sufhciently to cause a very delicate contact between the contact piece 6 and the contact screwl 6. As previously stated the circuit which is closed by contact piece 8 and the screw 6 includes the switch 31-38, the coil C, the battery 12 and the solenoids 3 and 4. The delicate pressure-which the contact piece 8 exerts against the screw 6 by virtue of the thermo-couple circuit is however so small that the contact resistance will not permit suiflct. it current to flow through the circuit from battery 12 to actuate the armature 5|. (opposite to that of battery26) so that the current which does flow through the circuit will cause the solenoids to react with the permanent magnet 5 to force the contact piece 8 tighter against the screw 6. 'I'he increased pressure between the contact piece 8 and the contact screw 6 will obviouslydecrease the contact resistance thereby increasing the ow through the circuit which increased flow in turn still further increases the pressure between the contact piece 6 and the screw 6 to again increase the flow. It therefore follows that regardless of the delicacy of the initial pressure of the contact piece 8 and the contact screw 6 as caused by the thermocouple circuit, said pressure will build up almost immediately until sulcient current iiows from the battery 16 to actuate the amature 5i. 'Ihe armature will thus react with the coil C to open the switch 46-41 immediately after the small flow through the thermo-couple circuit has caused the pendulum to deflect just sufficiently to the left to cause a very delicate contact between the contact piece 8 and the screw 6. As previously stated, the circuit which includes the switch 46-41 is the second or holding circuit through the coil B. The opening of the switch 46--41 as caused by contact between 6 and 8, will therefore release the armature 59 thus permitting the switches actuated thereby to return to the positions illustrated in Figure 1. The switch 31--39 being no w open, the ow from battery 12 through the solenoids 3 and 4 and coil C will discontinue, thus permitting the pendulum to again be influenced solely by the current flowing through the thermo-couple circuit and allowing the armature 5| to return to its normal position A to again close the switch 46-41.

It thus follows that regardless of the delicacy of the force which the pendulum may exert against the contact screw 1, the slightest contact between said screw and the contact piece 9 will, in the manner stated, cause the switches 29-49, 29-30, 31-38 and 69-10 to assume the positions illustrated in Figure 3. In this position the switch 29--49 closes the previously traced holding circuit through the coil B which maintains the switches in that position. 'I'he opening of switch 29-30 breaks the previously traced circuit which includes the battery 26, the coil A, the contact screw 1 and the solenoids l and 4, thus preventing any further influence from the battery 26 on the pendulum and at the same time deenergizing the coil A to again cause the opening of switch 4|42 'which switch was temporarily closed to cause the initial energizing of the coil B. The closing of switch 31-33 closes a gap in the circuit which includes the coil C, the battery 12, the solenoids 3 and 4 and the contact screw 6, and which circuit, in the manner previously stated, may now be closed by contact between 6 and l. The switch "-16 in the position The batte y 12 is however of such polarity` ing the holding circuit through B when the Y switch 46-41 is opened by the coil C. The opening of switch 31-38, Figure 1, breaks the previously traced circuit which includes the battery 12, the coil B, the contact screw 6 and solenoids 3 and 4, thus preventing any further influence from the battery 12 on the pendulum and at the same time deenergizing the coil C to again close .the switch 46--41 which switch was temporarily opened to break the holding circuit through coil B to permit the switch to assume the positions illustrated in Figure 1. The closing of switch 29-30 closes a gap in the circuit which includes the coil A, the battery 26, the solenoids 3 and 4, andthe contact screw 1 so that this circuit, in the manner already stated, may now again be closed by contact between 1 and 9. The switch 69-10 in the position illustrated in Figure 1 opens the circuit through the furnace.

The energizing circuit through the potentiometer wire 14 includes a battery 16 and a resistance R. It is therefore obvious that the brush 18 may be adjusted so that the drop across .the potentiometer will exactly balance the electromotive force from the couple 2| for any given temperature of the furnace. Let us assume for example that the potentiometer is adjusted for a furnace temperature of.1000 F. and that the furnace is at that temperature., Under these conditions there will obviously be no current owing through the thermo-couple circuit, there will be no reaction between the pendulum and the solenoids 3 and 4, and the pendulum will assume its null position asy illustrated. Ihe solenoids 3 and 4 are so wound that if the temperature of the furnace exceeds the temperature for which the potentiometer is set, the ow through the solenoids will be in the proper direction to cause the pendulum to deflect to the left thus estab- I -lishing contact between 6 and 8 which, in the manner already stated, causes the switches to assume the positions illustrated in Figure l, in which position the switch 69-10 will be open to deenerglze the furnace. piece 8 may, for a time, continue to touch the cont-act screw 6, the circuit through the solenoids from the battery 12 will, in the manner stated, be broken through the switch 31-38,thus permitting the pendulum to move to the right as the furnace cools. When the furnace has cooled below the temperature forwhich the potentiometer tentiometer will be greater than that of the couple and the current through the couple circuit will iiow in the proper direction to cause the pendulum to deflect` to the right, thus establishing contact between 1 and 9 which, in the manner stated, will cause the switches to assume the positions illustrated in Figure 3, in which position the switch 69`-10 will be closed to energize the furnace, Although the contact piece 9 may, for a time, continue to touch the contact screw 1, the circuit through the solenoids from the battery 26 will, in the manner stated, be broken through Although the contact is set, then the electro-motive force of the po- Cil the switch 29-30, thus permitting the pendulum to move to the left as the furnace temperature increases.

vThe brush 18 of the potentiometer may of course be set for any desired furnace temperature. When the temperature of the couple exceeds that for which the potentiometer is set, the slightest ow of current through the couple circuit will, in the manner stated, cause the switches to assume the positions illustrated in Figure 1, thereby opening the furnace circuit to lower the temperature, and when the temperature of the couple drops below that for which the potentiometer is set, then the slightest ow of current through the couple 'circuit will, in the manner stated, cause the switches to assume the positions illustrated in Figure 3, thereby closing the furnace circuit to increase the temperature. The regulator may therefore be actuated to maintain any desired temperature in the furnace depending upon the position to which the brush of the potentiometer is set. p

Although I have illustrated the moving element of the galvanometer in the form of a pendulum,v

the center of gravity of which is directly below the line on which it is pivoted, it is obvious, without in any way departing from the invention, that even more delicate effects may be obtained by pivoting the moving element of the galvanometer on a line at a slight angle to the vertical thus permitting a swinging movement of the movable element in a plane at a slight angle to the horizontal. The eiect of such an arrangement would be similar to that produced on a garden gatewhen the axis of the hinges is slightly tilted, thus permitting the gate to come to aflnal vertical position by gravity.

I claim:

1. In a device of the class described, the combination with a pendulum, the major mass of which consists of a permanent magnet, of a solenoid with which, when energized, the permanent magnet reacts to deflect the pendulum, a contact piece with which the permanent magnet makes electric contact when the pendulum is deflected in one direction, a second contact piece with which the permanent magnet makes electric contact when the pendulum is deflected in'the opposite direction, an independent circuit which includes the -solenoid for defiecting the pendulum, a second independent circuit which is closed by contact between the permanent magnet and the rst contact piece, 'said second circuit including the permanent magnet, the solenoid andthe ilrst contact piece, the purpose of said second circuit through the solenoid being to independently ener- 'gizethe solenoid to react with the permanent magnet to increase the contact pressure between the permanent magnet and the contact piece, and a third independent circuit which is closed by contact between the permanent magnet and the second contact piece, said third circuit including the permanent magnet, the solenoid and the second contact piece, the purpose of said third circuit through the solenoid being to independently energize the solenoid to react with the permanent magnet to increase the contact pressure between the permanent magnet and the second contact piece.

2. In a device of the class described, the combi- I nation with a pendulum, the major mass of which consists of a permanent magnet, of a solenoid with which, when energized, the permanent magnet reacts to deflect the pendulum, a contact piece with which the permanent magnet makesl electric contact when the pendulum is deflected in one direction, a second contact piece with which the permanent magnet makes electric contact when the pendulum is deflected in the opposite direction, an independent circuit which includes the solenoid for defiecting the pendulum, a second yindependent circuit which is closed by contact between the permanent magnet and the first contact piece, said second circuit including the solenoid for reacting with the permanent magnet to increase the contact pressure between the permanent magnet and the contact piece; a third independent circuit which is closed by contact between the permanent magnet and the second contact piece, said third circuit including the solenoid for reacting with the permanent magnet to increase the contact pressure between the permanent magnet and the second contact piece, means controlled by the second circuit for deenergizing the solenoid, and a second means for deenergizlng the solenoid, said second means being controlled by the third circuit.

3. In a device of the class ldescribed, the combination with a stationary coil, of a pendulum which is capable of reaction with the coil to move the pendulum from its normal position when the coil is energized, a circuit for energizing the coil to move the pendulum, a contact piece with which the pendulum makes electric contact when the coil is energized by the circuit, an electrical means which, when energized, closes a switch, a second electrical means which, when energized, opens a second switch, a second circuit for energizing the first electrical means, which circuit is closed by contact between the pendulum and the contact piece, said second circuit including the coil, the second switch, and the irst electrical means, and a third circuit for energizing the second electrical means, said third circuit including the rst switch and the second electrical means. J

4. In a device of the class described, the combination with a stationary solenoid, of a pendulum which is capable of reaction with thesolenoid to move the pendulum from its normal position when the solenoid is energized, a circuit for energizing the solenoid to move the pendulum, a contact-piece with which the pendulum makes electric contact when the solenoid is energized by the circuit, an electrical means which, when enera third circuit for energizing the second electrical -for energizing the second electrical means, said fourth circuit including the second electrical means and the third switch.

5. In a deyice of the class described, the combination with a pendulum, of a contact piecewith which the pendulum, when forced out of its normal position, makes electric contact to close a circuit through an electrical means, a second electrical means which, when energized, operates a switch to open the circuit, a. second switch actuated by the first electrical means which second switch, when the firstA electrical means is energized, closes a second circuit through the second electrical means, a third switch actuated by the second electrical means which third switch, when the second electrical means is energized, closes a holding circuit through said second electrical means, and a third electrical means included in the ilrst circuit which third electrical means, when energized, reacts with the pendulum to force it against the contact piece.

6. In a device of the class described, the combination with a pendulum, of a contact piece with which the pendulum, when forced out of its normal position, makes electric contact to close a circuit through an electrical means, a second electrical means which, when energized, operates a switch to open the circuit, a second switch actuated by the first electrical means which switch, when the rst electrical means is energized, closes a second circuit through the second electrical means, a third switch actuated by the second electrical means for closing a holding circuit through said second electrical means, a third electrical means included in the rst circuit which third electrical means, when energized, reacts with the pendulum to force it against the contact piece, an independent circuit which also includes the third electrical means, and a source of electrical energy in the independent circuit for energizing said third electrical means to react with the pendulum to force the pendulum out of its normal position.

7. In a device of the class described, the combination with a permanent magnet suspended in the form ol' a pendulum, of a contact piece with which the permanent magnet, when deflected counter-clockwise from its normal position, makes electric contact to close a circuit through an electrical means, a second electrical means which, when energized, operates a switch to open the circuit, a second switch actuated by the rst electricalmeans which switch, when the rst electrical means is energized, closes a second circuit through the second electrical means, a third switch actuated by the second electrical means for closing a holding circuit through the second electrical means when said electrical means is energized, a second contact piece with which the permanent magnet, when deflected clockwise from its normal position, makes electric contact to close a third circuit through a third electrical means, a fourth switch actuated by the third electrical means, said fourth switch opening the holding circuit when the third electrical means is energized, a mth switch for opening the third circuit, said fth switch being actuated by the second electrical means and opened thereby when said second electrical means is deenergized, a solenoid for reacting with the permanent magnet when said solenoid is energized, said solenoid being included in both therst and third circuits, a battery in the rst circuit of the proper vpolarity to force the permanent magnet counter-clockwise, a second battery in the third circuit o! the proper polarity.

magnet to exert a force on the pendulum, to defleet it from its normal position, a circuit which includes the pendulum, the first contact piece and the solenoid, a second circuit which includes .the pendulum, the second contact piece and the solenoid, a battery in the rst circuit for energizing the solenoid to force the pendulum clockwise, a second battery inthe second circuit for energizing the solenoid to force the pendulum counter-clockwise, a switch in the first circuit the opening of which switch is controlled by the first circuit and the closing of which is controlled by the second circuit, a second switch in the Y second circuit the opening of which second switch is controlled by the second circuit and the closing of which is controlled by the first circuit, and a third circuit which includes the solenoid for deilecting the pendulum out of its normal position and against the rst or second contact piece to respectively close the rst or second circuit.

9. In a device of the class described, the combination with a galvanometer consisting of a movable member and a coil which reacts with a permanent magnet to .deflect the member, of a switch which is closed by the coil when the coil is energized, an electrical means, a circuit through' the coil and the electrical means which circuit is closed by the switch, a second switch operated by the electrical means, when energized,

to close a second circuit through a second electrical means, a third switch operated by the second electrical means, when energized, to open the first circuit, a fourth switch operated by the second electrical means, when energized, for closing a holding circuit through the second electrical means, and an independent circuit through the coil for actuating the rst switch.

` l0. In a device of the class described, the combination with a galvanometer consisting of a movable member and a coil which when energized reacts with a permanent magnet to deflect the member, of a switch which is closed by the coil when energized-in one direction, an electromagnet, a circuit which is closed by the switch, said circuit including the coil and the electromagnet in series, a second switch operated by the electro-magnet, when energized, to close a second circuit through a second electro-magnet, a third switch operated by the second electromagnet, when energized, to open the rst circuit, a fourth switch operated by the second electromagnet, when energied, to close a holding circpuit through the second electro-magnet, a ilfth switch which is closed by the coil when energized in the opposite direction', a third electro-magnet, a sixth switch which is closed by the second electro-magnet when energized, a fourth circuit which is closed by the mth switch said fourth 'circuit including the coil, the sixth switch and the third electro-magnet in series, a seventh `switch operated by the third electro-magnet,

when energized, to open the holding circuit thereby deenergizing theI second electro-magnet to open the sixth lswitch and again close the third switch, a battery in the rst circuit oi the proper polarity to energize the coll in the proper direction to close the first switch, a second battery in the fourth circuit of the proper polarity to energize the coil in the proper direction to close the ilfth switch, and independent means for enerreacts with a permanent magnet to deflect the member, of a switch which is closed by the coil when energized in one direction, an electro-magnet, a circuit which is closed by the switch, said circuit including the coil and the electro-magnet in series, a second switch operatedby the electro-magnet, when energized, to close a second circuit through a second electro-magnet, a third switch operated by the second electro-magnet, when energized, to open the rst circuit, a fourth switch operated by the second electro-magnet,

when energized; to close a holding circuit through-v electro-magnet in series, a seventh switch operated by the third electro-magnet, when venergized, to open the holding circuitthereby deenergizing the second electro-magnet to open the sixth switch and again close the third switch, a battery in the first circuit of the proper polarity to energize the coil in the proper direction to close the rst switch, a second battery in the fourth circuit of the proper polarity to energize the coil inthe proper direction to close the fth switch, a thermo-couple for energizing the coil, an independent circuit which includes the coil and the couple, and an adjustable potentiometer in the independent circuit for balancing the electro-motive force of the couple for any given temperature of the couple.

12. In a device of the class described, the combination with a pendulum, of a permanent mag-- lum and the contact piece, a second contact piece with which the pendulum, when deflected in the opposite direction makes electrical contact and means for increasing the contact pressure between the pendulum and the second contact piece, said means consisting of a second independent circuit of opposite polarity which includes the solenoid and is closed by contact between the pendulum and the second contact piece.

13. In a device of the class described, the combination with a solenoid included in each of three dierent circuits, of a pendulum, a permanent magnet fastened to and forming part of the pendulum, said permanent magnet reacting with the solenoid to deect the pendulum when the solenoid is energized; a thermo-couple and a potentiometer for balancing the electro-motive force of the couple, said thermo-couple and potentiometer being included in the first circuit for energizing the solenoid to deflect the pendulum, an electro-magnet,'a switch which is opened by a second electro-magnet when energized, and a second switch which isclosed by the pendulum when the solenoid is energized in-one direction, said first electro-magnet and said first and second switches being included with the solenoid in the second circuit, a third electro-magnet, a third switch which is closed bythe second electro-magnet when energized, and a fourth switch which is closed by the pendulum when Athe solenoid is energized in the opposite direction, said third and fourth switches and the third electromagnet being included with the solenoid in the third circuit, a fifth switch which is closed by the first electro-magnet, when energized, for,

closing a fourth circuit through the second electro-magnet, a sixth switch actuated by the second electro-magnet for closing a holding circuit through said second electro-magnet when the second electro-magnet is energized, a seventh switch which is opened by the third electro-magnet, when energized, for opening the holding circuit, and an eighth switch actuated by the second electro-magnet for opening and closing a fifth circuit. d

14. In a device of the class described, the combination with a relay, of a first, second and third switch each of which is closed by the relay when energized and opened by the relay when deenergized, a fourth switch which is opened by the relay when,energized and closed by the relay when`deenergized, means actuated by the relay for clo'sing the flrst switch before the fourth switch is opened, a second relay, a fifth switch which is closed by the second relay when energized and opened by said relay when deenergized, a third relay, a sixth switch which is opened by the third relay when energized and closed by said relay when deenergized, a pendulum, a permanent magnet which forms part of the pendulum, a solenoid which when energized reacts with the magnet to force the pendulum from its normal position, a seventh switch which is closed by the pendulum when forced in a counter-clockwise direction, an eighth switch which is closed by the pendulum when forced in a clockwise direction, a battery of given polarity, a circuit which includes the battery, the solenoid, the pendulum, the seventh switch, the second relay, and the fourth switch, a second batteryof opposite polarity, a second circuit which includes the second battery, the solenoid, the pendulum, the eighth switch, the second switch, and the third relay, a third circuit which includes the fth switch, the first relay and the sixth switch, 'a

fourth circuit which includes the first switch,

"' the first relay, and the sixth switch, a thermocouple for energizing the solenoid to deect the pendulum, an adjustable potentiometer f or balancing the electro-motive force of the couple, and a fth circuit which includes the couple, the potentiometer and the solenoid.

15. In a device of the class described, the combination with a pendulum, of a permanent mag- -net fastened to the pendulum, electro-magnetic ond circuit through a switch included in said second circuit.

16. In a device of the class described, the combination with a pendulum ofl a permanent magnet fastened to the pendulum, electro-magnetic means for reacting with the permanent, magnet to deflect the pendulum ink a counter-clockwise or clockwise direction depending upon whether the currentl ow through the electro-magnetic means is in one direction or the other, a contact piece with which the pendulum makes electric contact when deflected counter-clockwise, a second contact piece with which the pendulum makes electric contact when deflected clockwise, a circuit through theelectro-magnetic means which is closed by contact between the pendulum and the first contact piece and which circuit includes a battery of given polarity, a relay actuated; by the' circuit to operate a second relay which second relay when energized opens a switch to open the circuit, a second switch which is closed by the second relay to close a second or holding circuit through the second relay, a third circuit through the electro-magnetic means, which circuit is closed by contact between the pendulum and the second contact piece and which circuit includes a second battery of opposite polarity, a third relay actuated by the third circuit to open the holding circuit through the second relay, a th'ird switch, included in the third circuit, which switch is opened by the second relay when deenergized, and anv independent circuit through the electro-magnetic means for deecting the pendulum against one or the other of the contact pieces.

17, In a device of the class described, the combination with a pendulum, the major mass of which consists of a permanent magnet, of an electro-magnet located in a fixed position which, when energized, reacts with the permanent mag net to deflect the pendulum, a contact piece with which the permanent magnet makes electrical contact when the pendulum i`s deected, a cirl cuit which includes the electro-magnet and a source of electrical energy for detlecting the pendulum against the contact piece, a second circuit which is independent of the rst circuit and which includes the electro-magnet and an independent source of electrical energy for forcing the permanent magnet against the contact piece, said second circuit being closed by contact between the permanent magnet and the contact piece, and electrical means in the second circuit `for simultaneously closing a third circuit and opening the second circuit.

18. In a device of the class described, the combetween the permanent magnet and the contact piece, said second circuit including the electros-magnet and a battery which is independent of said source of electrical energy, said battery' energizing the electro-magnet to react with the permanent magnet and the contact piece, and electrical means in the second circuit for cutting out the energy from the battery to the electro- .magnet and simultaneously closing a third ein cuit.

19. In a device of the class described, the com= bination with a suspended permanent magnet, of a xed coil which, when energized by a source oi'- electrical energy through an independent circuit, reacts with the magnet to deilect the magnet from its normal position, and means for closing a second electric circuit through thefcoil. said means being actuated by the force of reaction between the magnet and the coil when said coil is momentarily energized by a second and independent source of electrical energy substantially as described. f

20. In a device of the class described, the combination with a pendulum, ot` a permanent magnet which forms part of the pendulum, a solenoid with'which the magnet reacts, when the solenoid is energized to detlect the pendulum, a circuit which includes the solenoid and a source of electrical energy to deilect the pendulum against a contact piece, means for increasing the contact pressure between the pendulum and the contact piecef said means consisting of a second-source of electrical energy of the proper polarity in an independent circuit which includes the solenoid and is closed by the initial contact between the pendulum and the contact piece, and electrical means controlled by-the second circuit for cutting out the second source oi electrical energy.v

FRI'IZ FREDERICK UEHLING.

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