US2036091A - Electrical reproducing device - Google Patents

Description

March 31, 1936.

c. P. MITCHELL 2,036,091 ELECTRICAL REPRODUCING DEVICE Filed Dec. 4, 1931 3 Sheets-Sheet J,

INVENTOR dim/a WZW WZAW ATTORNEY-7 March 31, 1936. c T E 2,036,091

ELECTRICAL REPRODUCING DEVICE Filed Dec. 4, 1931 3 Sheets-Sheet 2 O M I 15 e 4 ,27 Z 14 g 25 if E 45 n L a 17 40 INVENTOR ATTORNEYJ March 31, 1936. c. P. MITCHELL ELECTRICAL REPRODUCING DEVICE Filed Dec. 4, 1931 3 Sheets-Sheet 3 INVENTOR ATTORNEYS Patented Mar. 31, 1936 ELECTRICAL nnrnonucnvo DEVICE Curtis P. Mitchell, Cincinnati, Ohio, assignor to The Palmer Company, Cincinnati, Ohio, a corporation of Ohio Application December 4, 1931, Serial No. 579,038

4 Claims.

This invention relates to electrical apparatus and is particularly directed to an apparatus or system for electrically reproducing motion at a location remote from the location at which it is applied. More specifically, the invention is utilized as an electrically operated'system for reproducing, recording, or showing temperatures at points removed from the environment, the temperature of which is being determined. 1

It is an object of this invention to provide an apparatus or systemior electrically reproducing thermostatically detected temperature changes by means of a unit placed at the environment of heat change which may be a theatre, an oven, etc and connecting this unit by electrical means to a receiving unit which may be located at a remote point such as theoutside of the theatre or the recording room of a bakery or extremely remote points, the receiving apparatus receiving signals from the sending device by electrical control and converting them into mechanical this character which is extremely sensitive and which, therefore, transmits the very slightest change in temperature and immediately displays or records the change simultaneously with the occurrence thereof. Moreover, it is arranged that, in the event of power failure in the electrical connecting means between the sending and receiving devices, these devices will automatically operate when the power is restored for quickly and accurately reproducing the temperature reading existing at the time of power restoration without requiring any resetting of the apparatus. For this purpose, the synchronous arrangement of the devices is not destroyed by power failure and the relation of the position of the temperature actuated element relative to the temperature is constantly maintained.

It is a more general object of this invention to provide a system and apparatus for electrically electrical elements andconnections of the present apparatus and system.

Figure 2 is a top plan view of the sending unit showing the mechanical construction thereof in detail. I

Figure 3 is a side view of Figure 2, further detailing the sending unit.

Figure 4 is a front view, partly broken away, of the recording unit. I

Figure 5 is a side view ofFigure 4, certain parts thereof being shownin section for more fully illustrating the structure.

Figure 6 is a bottom view of the recording unit.

Figure 7 is a sectional view taken on line 1-1, Figure 6, detailing the electrical connections to the conductor fingers which control the operation of the recording motor. 7

Figure 8 is a diagrammatic view illustrating a portion of the wiring for the purpose of showing vthe voltage connections for alternate operation of the motors, this view illustrating the sending motor in operation.

Figure 9 is a diagrammatic view similar to Figure 8, but showing the receiving motor in operation and the connection effective for'pre- '25 venting concurrent operation 01' the sending motor. v y In practice, the present invention is constructed in two units, namely a sending unit It and'a recording unit H, connected by electrical wiring, the distance between these units being immate rial since it may range from adjacent locationsto verw remote locations. The apparatus is applied for'recording temperature in the present illustration. In practice it may. be arranged that the sending apparatus or unitis located adjacent an oven, as in abakery, with a thermally sensitive member disposed in the oven and the recording unit may be located in the omce or an executive room as when the apparatus is appliedto 0 a large institution.

The sending unit 10, generally described, includes a motor II, a thermally sensitive member I: operatively carrying a contact l4, contacts I, I5, one foreach direction of the motor, these contacts alternately engageable by. the contact I! of the thermally sensitive member, a contactor l5 driven by the motor 12 adapted to cooperate with a series of stationary contacts 11 for sendme through recording impulses, the motor transmission including a transmission connection I. to the two contacts thereof for the purpose of moving the same and disestablishing contact after a certain temperature change has been fully recorded. 66

Referring specifically to Figure 2, the motor I2 is mounted on a panel board l9. As an example, 110 volts are supplied to the motor through electrical leads 2!) and 2|. The sending motor re- 1 quires around 90 to 100 volts for operation. One

of. the leads on the panel board, namely 20, is

connected directly to the motor ,and the other,

namely 2|, is connected to the outer end of the thermally sensitivemember l3. The member l3 to the panel I9.

is a Bourdon tube being filled with an expansible liquid whereby the tube coils and uncoils as the temperature changes occur and transmits movement. I j e The inner end. of this coiled tube is fastened to the panel board by means of an anchorage 23. The inner end,of the tube l3 includes an axially extended tube portion l3 which passes through the panel l9 and may be situated more directly in the environment of the heat, as through the side of an oven. The outer end of the Bourdon tube carries a contact arm 24 to which the lead 2| is connected, the outer end of the contact arm 24 including ,the contact l4 providing contact faces disposed at opposite sides thereof. These contact faces, respectively, are adapted tooper- T ate for making or breaking contact with the contacts l5, l5, constituted by the heads of screws mounted in a carrier block 25.

The carrier block 25 comprises a nut 26 translated by a motor driven screw 21 and arms 28 of insulation attached to the'nut at each end thereof. Each of these arms mounts a respective contact IS, the heads ofthe contact screws being opposingly related. Each of the contact screws are. connected to the motor by a respective lead 29 and thewiring of the reversible motor as shown in the .wiring diagrams is arranged so that contact of the thermostatically operated contact with a particular contact screw produces a re- 'spective direction of motor operation.

The motor shaft 30 includes a pinion 3 2 drivinga gear 33 pinned to the screw shaft 21. The screw shaft 21 is mounted in brackets 3| attached Rotation of the screw-shaft translates the carriage 25, the direction of the thread onthe screw being such that upon a contact with one of the contact screws, the resultant rotation of the motor movesthe particular contact screw 15 away from the contact for disestablishing the contact after the thermostatically moved contact becomes stationary and the full .temperature change in the'particular direction has been recorded. In order to prevent rotation 1 of the nut 26 with the' screw shaft, an arm 34 extends. downwardly from the nut-and-includes a channel 35 engaging a guide 36 inparallelism with the screw shaft and secured to the panel I9.

The screw shaft carries the moving contactor |6.on its outer end, this contactor consisting of a piece-of spring plate attached between cooperating'nuts 31. The intumed end of the spring plate contactor moves over the series of segmental statrical lead it extends to-a terminal 4|: mounted g on the panel. Thusit is seen that as long as the thermally sensitive member is active due to temperature change, the contact l4 thereof is moved against one or the other of the screw contacts I 5' and rotation of the contactor l6 continues, the contactor moving from one segmental plate I! to another in its course of travel. It will be noted that these segmental contactor plates of which there are three in this instance, are spaced apart sufficiently for the contactor finger to be entirely clear of any plate at the time of its passage from one contactor plate to another. The purpose of this will be made fully apparent at a subsequent point in this description.

' There is a fourth terminal 44 on the panel board Hi to which the current is supplied from the other input or supply terminal 42 by an electrical lead 43. From these four terminals, electrical leads 45, 46; extend any distance required to the receiving or recording apparatus, the circuit from 43, terminal and lead as one side and through The recording unit 11 includes a-pilot motor of the reversible type, a. recording instrumentality or stylus 4'| actuated by a motor 48, an exempliflcation of which will be given later, and a double contactor 49 driven by the motor including. diametrically opposite contacts 50, 50,- connected to the respective sides of the motor wiring .for reversal thereof. This plural contact on the motor shaft is adapted to engage segmental con tact plates 5| of the same nature and general arrangement as the contacts I! on thesending unit "I.

The recording instrument in this instance, described in detail, consists of a base plate 52 upon which is secured a face plate or support 53 for a rotating disc 54 having graph markings thereon including a related temperature scale and time chart, the degrees of temperature arranged from low at the inside circle to high at the outside circle, and the time chart constituted by hour lines on the line taken by a direct: swing of the recording pencil 55 across the temperature indicating circles. Thisface plate 53 is supported by brackets 53': Thedisc 54, which may be of disc against a shoulder 60 of the shaft.

The motor which controls the position of the recording finger is approximately a 30 volt motor and its control is accomplished through the segmental plates 5|, and the contactors 50, previ-. ously described. V

' The finger SI of the recording device 41, which carries the pencil or a writing instrumentality of any sort, is mounted on a pivot rod 62 at its lower end and includes a hub 63, to which hub a second finger 64.is attached, this finger outer end engaged over a-pin 66 extending from a nut 61 translatably mounted on a screw shaft 68 driven by the motor 48. "The motor shaft 69 includes a worm l0 driving a worm wheel 1| pinned on the screw shaft 168.. The screw shaft 68 is mounteddn bearing brackets 12 attached to the base panel 52 of the unit.

1 Upon one end of this shaft and associated with the stationary contacts 5| mounted on one of the bearing brackets l2 are the contactors 5|, 5| previously referred to. The contactors SI, 58 are disposed at respective sides of the .bearing bracket 12 and are suitably insulated from each other and from the shaft. Each transmits electrical energy to the motor through a respective brush I3, I3. These motor control contactors 5|, 5| each consistof a blade having an inturned outer end ridingupon the contact plates 5| attached to the bearing bracket or panel 12. Since this bearing bracket is formed of insulating material, the contact plates are always from each other. The contact plates 5| are sectional, each including sections disposed upon the respective, sides of the panel or bearing brackets. These sections are duplicates as to length and position and are electrically joined and fixed to the panel by means of screws llfconnecting the same through the panel.

of which hub a brush IS in the form of a spring blade is disposed. In the-instance of the inner assembly,- a shoulder is provided on the screw.

an electrical lead 82 connectedthereto extending from terminals 83. on the base panel 52. The

terminals 88 are connected to the sending unit.

II by means of the leads 4'6, any one of these connections representing one side of the current flow from the sending device. The contactors 50, 5| on the receiving device are diametrically related so that they bear upon diiferent contacts SI of thestationary series. The brushes 13 which are attached tothe base panel of the unit are connected to the wiring of the motor by leads '4. for respective directions of drive thereof. The other side for the current flow to the motor l8 comes through the lead from the sending device to a terminal I! on the panel 52 of the receiving unit II and thence to the motor 48 through a l8.

Operation of thc system The drawings (see Figure 1) illustrate the device at rest, each of the respective contactors II, II, 50, on the sending unit II and the receiving or recording unit H having coasted from one contactto the next adjacent contact, the inertia of the motors l2, ll, being sufilcient for this purpose. .The swinging contact it carried by the h rmally sensitive element IS on the sending unit II is poised midway between the reversing contacts II, II at this time. i

As the temperature rises or falls and the thermally sensitive member is effected, the swinging contact I thereof moves into contact with either one or the other of the contacts I5, I, carried by the carrier 2. This establishes a circuit through to the motor l2 either for right or left hand drive,

. the current travelling tothe motor through the direct connection 20 and through the connection 21 to the contact arm 24 of the thermally sensitive member, thence passing from contact I into one or the other of the contacts l5 and to the particular wiring of the motor I! by way of one of the leads 2!. This starts the motor in one or the other directions and the screw shaft 21 is thereby rotated moving the contactor IS the length of the particular stationary contact II on which it is resting at the time, whereupon it clears that contact and touches the next contact I 'l a It will be noted that the contactor ii of the sending unit In and the contactors 50 of the receiving unitare related to provide that the contact 'll upon which the-contactor l6 ofthe sending .unit first moves connects the electrical energy to a dead contact 5! of the series on the,

receiving unit, that is to say, one which is not contacted at the time by either of the contacts 50. However, as the contactor 16 leaves the particular contact I! and engages the next contact .ll, it will then establish an electrical connection from the-main line input terminal 39 through the particular contact I l, thence through a particular electrical connection 46 between the to the second contact 5| of the receiving unit which, due to the fact that one of the pair of contactors 50 of the receiving unit is resting, thereupon, connects the current through said contactor 50 to the particular side of the receiv- 7 ing or recording motor 48 which is active through its transmission for causing movement of the recording finger SI swinging the same in an are I generally radially relative to the rotating recording disc drawing thereupon a line indicating the rise or fall in temperature.

It is arranged that the motor ll of the sending unit It! will not operate when the motor 48 of the receiving. unit is operating due to voltage and resistance conditions, which will be hereinafter d8SCl'ib'3duS0 that the moment the contactor of the sending unit establishes the circuit for the impu se to the receiving motor, the sending motor stops momentarily. In the preceding description, the movement of the respective contactors has been assumed tovbe clockwise, it being ap parent thatif the swinging contactor ll of the thermally sensitive element l3 has moved to the opposite. contact l5, anticlockwise movement of these contactors would have resulted and the current fiow would have been established to the receiving or. recording. motor 8 by way of the third contactors l1, SI of the respective series.

Going back to thefirst description, it will be apparent that whenthe receiving orrecording motor 48 has been set in motion. it will move. by means of the shaft 88, the contactors 58, 50 which control it until the particular one being described leaves the second contact of the series of the recording or receiving unit, at which time the re-.

cording motor will stop for the reason that the next contact is a dead one, that is, not connected through'to the main line by way of a contact I! of the sending unit.-

As soon as the recording motor 48 stops, the sending motor I! will again start, since there is then suificient voltage for operation, and the con- .tactor l5 thereof will move to the third contact 41 in a ciockwise direction. This again establishes cur as long as the thermally sensitive member is eifected by temperature changeand is continuing a rise or fall since the swinging contact will be continually urged againstthe-particular contest 15 even though the sending motor is elective for 'slowly -,drawing the contact it away from the swinging contact, the pitch of the screw 2'! beingproportioned for a slow'movement of the nut car'- v 1 sistor brin 92.6-volts across the resistance moried contacts l5, l5. s l The moment; the rise. or fall of temperature ceases, the sending motor I! will be-eflective-for l breaking the contact betweencontacts ll i5 and disesta'blishingthe circuit to the sendingmotor by its own action. The swinging contact II is related to the contact screws l5, so that a very slight movement thereof is eflective for recording a temperature change,.since the making and breaking of contact requires. very little movement, thus resulting in a very sensitive recording or display of temperature. It isapparent that the thermally sensitive element 13 may be of any type desired and capable of imparting a motion to a particularidouble contact along the lines of that described.

f It is,necessary that the sending motorpause or operate intermittently for preventing the con- 2 tact l6 operated thereby from.running ahead as stated before, the sending motor and the reapproximately 400 olimafi Therefore, the drop of the contactors 50, 59 of the receiving device andfor keeping these contacts in perfect relation for establishing .tbe successive circuits through the respective electrically connected sta-' tionary contacts 11, Si, of the units. Therefore,

oeiving motor cannot operate concurrently. As a practical electrical'arrangement for accomplishing this result a resistance 90 of 75 ohms is inserted in the main line, this resistance being inserted in front of both .0!- the motors.- The larger motor l2,-namely. the sending motor. requires -90 volts or-over for operation.

This motor I: is calculated at a resistance or across resistance 90 is 17.4 volts (see later quations and Figures 8 and 9 of the drawings) and the input voltage to the sending motor is 92.6

volts; Since the sending motor will operate on 90 volts or more, the voltage 92.6, being the maximum supply to the sending otor, will be sufflcient for operating this motor. However, when the contact "of the recording unit closes the circuit through to the recording motor. 59, thereby shunting the sending motor,

neglecting the conductance of the. sending motor, the voltage will be as follows: Since the receiving motor ar -recording motor 48 is calculated to operate on a voltage of from 25 to 30 volts and has been arranged at a resistance of about 25 ohms, thevoltage drop through ,the resistance figures at 82.5 volts and the voltage across the motors at 27.5 volts. ginceithe voltage drop throughthe .jll is now 82.5 leaving only 27.5 volts input to the sending" 1 motor ii, the: sending motoris inoperative.

Therefore, the two motors work intermittently and alternately, the sending m'otorclearing' one contact which-requires a certain amoimt oi movement equivalent to about one third revolution of the shalt and makes another, the making of the second contact establishing the circuit to the recording motor which operates as long. as a particular'contact is maintained which is equivalent to about one-third revolution of the contactor driving shaft of this unit. I o

Otherwise stated, the sending motor stops due tolack of suillcient voltage to operate it when the receiving motor. is connected. The voltage applied across the, terminals 39 and "can be considered as constant, say at 110 volts; When thesending motor-l2 with-the resistance of 400 Ohms is-ponnected across the line in series with resistor 90501375 ohms, and motor 49 is disconnected, a shown in Figure 8, the 110'vo1ts are divided mmga drop of 17.4 volts across the retor 12. Since this motor requires over volts, it will with this@ connection. If the motor 4!; with aresistance of 25 ohms is connected in parallel with motor 12, the combination in series with the resistor9il, as. shown in Figure 9, motor 12 will not run. The motor, resistance of motors l2 and 48, of 400 and 25 ohms respectively, in parallel have a series resistance equiv- I alent to 23.5 ohms, making the total resistance across the .line, the 75 ohms of resistor 90, plus the 23.5 ohms equivalent resistance which is.

98.5 ohms. The current through-resistor so at; voltsjis 110 divided by 98.5 or1.12 amperes.

The voltage drop across resistance 90 is 1.12 times 75, or 83.7 volts, leaving a voltage drop of 26.3

across each of the motors l2 and 48. .Since motor "requires 90'v'olts or more, it will not run,

. but,m'otor 48, 'requiringfrom 25 to 30 volts, will run on the 26.3 volts available. The. increase in current, due to the current requirements of motor 48, has increased the voltage drop across resistor 99 to such an extent that the remaining volts oi the 110 volts of the line are insuflicient to operate motor 12. Thus the circuit which comtoFigures 8 and 9 for the following equations.

- From Figure 8 the following equations are drawn which will explain in detail the voltages eiIective-forpermitting operation of the sending tor-is in open circuit'and the sending motor is operative. When the circuit is closed to the recording'or receivlngmotor, referring to Figure 9, the

equations neglecting the'resistance of the motor I: will be as follows:

\, 25 7 il-76X 110-27-5 volts.

These equations are based on' the voltages coming. through the respective" input leads and the respective resistances when the entire current or recording motor. 1t willbe apparent that due to this wiring arrangement, the synchronized action of the units is always maintained and'mere particularly the relation of the thermally sensitiveelement and the recording finger is always maintained.

Having described my invention, I claim:

1. The combination with a temperature recording device of a thermally sensitive element including a movable contact, a motor, electrical connections to said motor, a resistor in one of said electrical connections, one of said electrical connections including said movable contact, a pair of motor control contacts alternately engageable by said movable contact for starting and direction control of said motor in reversing directions, means driven by said motor for disestablishing contact between said motor control contacts and said movable contact, a contactor driven by said motor, a series of contacts suc-\ 'cessively and independently engageableby said contactor, a second set of contacts located at the point of temperature record corresponding in number to the first set, the corresponding contacts of said sets of contacts respectively in electrical connection, a motor driven contactor element for traversing the contacts of said second set, said contact element normally out of phase one contact with respect to the contactor of said first set of contacts, a motor driving said contact element and electrically connected thereto for eifecting its own stopping control, said second series of contacts arranged relative to said con-. tact element whereby contact between said element and a contact of the series is always maintained, said second set of contacts and said contactor element constituting a switch controlling the completion of thecir'cuit of the motor driving the same through a circuit including a contact and the contactor of said first series, said second motor when in electrical connection with said second contacts arranged to be in parallel with said first motor, and said motors when parallel connected arranged to be in series with said resistor, said first motor requiring substantially line voltage for operation, said second motor requiring relatively less than line voltage for operation, said motors having resistances adapted when connected in parallel with each other and in series with said resistor to reduce the voltage to a value suflicient to operate only the second motor and insuflicient to operate the first motor.

2. Switchgear for remotely electrically indicating physical change, comprising, a pair of multiple switches, each comprising a plurality of contacts and a contactor element for traversing the same, the respective contacts of said switches respectively in electrical connection, motors for respectively driving each of the contactors of said switches, said motors in common partial circuit connection, a resistance included in the circuit to one of said motors, the contactor of one of said switches electrically energized, the contactors of said switches normally out 01' phase one contact, a pilot switch having an element responsive to physical change alternately oooperating with oppositely arranged contact elements for starting and direction control of one of said motors in reversing directions, said oppositely arranged contacts mounted for unitary movement to disrupt and alternate motor direction control through said pilot switch element responsive to physical change, the motor of said second switch in circuit completing connection with said first motor through the contactor of said second set of contacts and driving said second contactor to effect its own stopping control, said motors electrically connected to be in parallel when said partial common circuit is completed through said second switch and in series with said resistance, said second motor requiring comparatively less line voltage for operation than said first motor, whereby the magnitude of the resultant voltage in the circuit when the motors are so connected is insufilcient for operation of said first motor but suificient for operation of said second motor.

3. In an apparatus of the type-described, an electric motor driven switch controlling a plurality of controlling circuits, a second electric motor driven switch, the corresponding poles of said motor driven switches respectively in circuit connection, a thermo pilot switch having a thermo element alternately cooperating with oppositely arranged contact elements for starting and. direction control of one of said motors, said contacts mounted for unitary movement to disrupt and alternate motor direction control through said thermo switch element, said motors in common partial circuit connection, one motor driven switch controlling the completion of the circuit to the other motor through said switch of said second motor in reversing directions for operative control, the operation of said second motor through its switch effecting its own stopping control, the installation of the second motor into the circuit reducing voltage potential in the entire circuit to a value insufiicient to drive the motor subject to theme pilot switch control.

4. In an apparatus of the type described, an electric motor driven switch controlling a plurality of controlling circuits, a second electric motor driven switch, the movable elements of said switches normally out of phase one contact in either direction, the corresponding poles of said switches respectively in circuit connection, a thermo pilot switch having a thermo element alternately cooperating with oppositely arranged contact elements for starting and direction control oi! one of said switch motors, said contact elements mounted for unitary movement by the motor controlled thereby, to disrupt and alternate motor direction control through said thermo switch element, said switch motors in common partial circuit connection, one motor driven switch controlling the completion of the circuit to the other motor through said switch of said second motor in reversing directions for operative control, the operation of said second motor through its switch effecting its own stopping control, the installation of the second motor into the circuit reducing voltage potential in the entire circuit to a value insufficient to drive the motor subject to thermo pilot switch control.

- CU'R'IIS P. MITCHELL.

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