US2569397A - Electrical energizing means for limit control devices and the like - Google Patents

Description

Sept. 25, 1951 P. L. BETZ 2,569,397

ELECTRICAL ENERGIZING MEANS FOR LIMIT CONTROL DEVICES AND THE LIKE Filed May 24, 1949 A.C.INPUT AC. O UTPUT INVENTOR. FhuL L. Bel'z.

WMZam/Mm ATTORNEYS Patented Sept. 25, 1951 ELECTRICAL ENERGIZING MEANS FOR LIMIT CONTROL DEVICES AND THE LIKE Paul L. Betz, Baltimore, Md., assignor to Consolidated Gas Electric Light and Power Company of Baltimore, Baltimore, Md., a corporation of Maryland Application May 24, 1949, Serial No. 95,130

8 Claims.

This invention in its broader aspects relates to an electrical device which, upon opening of a circuit therein, causes an impulse to be generated which may be used to actuate an electrically or electromagnetically controlled mechanism. In a narrower sense, and as a specific application of such a device, the present invention relates to an electrical device which, upon opening of a circuit therein, will cause a thermoelectrically controlled mechanism to be operated, notwithstanding the continued generation of thermoelectric current, as if the thermoelectric current had passed below a predetermined value. By way of illustration, the invention will be particularly explained with respect to its latter use, but it is to be understood that the electrical device for generating an impulse on opening of a circuit is of wider utility as will be apparent to those skilled in the art.

In many electrical circuits energization of limit control means is eiiected by closing a switch in a control circuit. For example, in my pending application Serial No. 653,494, filed March 11, 1946, now patent No. 2,505,730, dated April 25, 1950, I have disclosed a thermoelectrically actuated shut-off valve used to control the flow of fuel to a main burner. A pilot burner associated with\ the main burner serves the double purpose of igniting the fuel at the main burner and of heating the hot junction of the thermocouple of the shut-off valve. The main burner in this example supplies heat to a water heater, the tank of which is provided with a switch responsive to the temperature or pressure of the water within the tank. This switch is so arranged that as long as the water temperature or pressure is below a predetermined value, the switch contacts remain open, and, upon attainment of the predetermined temperature or pressure, the contacts close. Closure of the switch contacts causes alternating current to be supplied to the thermoelectric circuit of the shutoff valve to cause the valve to close. The switch is required to close only when an abnormal temperature or pressure occurs. In said application this limit control operation is accomplished by the superposition of alternating current on the direct current of the thermocouple, and this causes the shut-off to close even though normal thermoelectric current is flowing.

In certain cases it is desirable that the superposition of alternating current on the thermoelectric current be occasioned by the opening of a circuit, as by a switch, when an excessive temperature or pressure occurs, rather than a closing thereof. This introduces a full-safe" characteristic, which may also be effective upon the occurrence of a broken wire, failure to make electrical contact, etc., to cause the shut-off valve to move to its inoperative position.

It is an object of this invention to provide an improved system to effect actuation of a safety device upon opening of a control circuit.

Another object of this invention is to provide an improved electrical actuating device which, upon opening of a circuit therein, will generate an impulse that can be used to actuate an electrically or electromagnetically controlled mechanism.

Another object of this invention is to provide a thermoelectrically controlled mechanism with improved electrical means which, upon the opening of a control circuit, will cause the thermoelectrically controlled mechanism to be actuated as if the thermoelectrical current had passed below a predetermined value.

Another object of this invention is to provide a device of the type characterized which is simple in construction and one which may be readily incorporated in existing systems as well as embodied in new systems for the purposes of effecting actuation of an electrically or electromagnetically controlled mechanism upon an opening of a control circuit.

In brief, the control device of the present invention comprises a pair of transformers having their secondary windings connected in series and their primary windings connected in parallel, the secondary windings being so constructed that when energized the resulting voltage is zero or substantially zero, but when the circuit of one of said primary windings is opened, the voltage generated in the secondary winding associated with the other primary winding is no longer balanced out, but is available for use in actuating an electrically or electromagnetically controlled mechanim. As applied to the actuation of a thermoelectrically controlled mechanism, said unbalanced voltage in the active secondary winding is utilized at the thermoelectrically controlled mechanism to produce an actuation thereof such as would arise if the thermoelectric current passed below a. predetermined value.

The invention is capable of being embodied in a variety of ways as will appear from the ensuing description, and it is therefore to be expressly understood that the embodiments selected for illustrating the application of the invention are not to be construed as defining the limits of the invention, reference being had to the appended claims for that purpose.

Referring in detail to the accompanying drawings, wherein the same reference characters are used to designate corresponding parts in the several figures,

Fig. l is an electrical diagram showing an embodiment of the electrical device for generating an impulse upon opening of a control circuit;

Fig. 2 is a diagram illustrating one way of applying the impulse derived from the device of Fig. 1 for actuation of a thermoelectrically controlled safety device;

Fig. 3 is a diagram illustrating another way of applying the impulse derived from the device of Fig. 1 for actuating a thermoelectrically controlled safety device; and

Fig. 4 is a diagram illustrating yet another way of applying the impulse derived from the device of Fig. 1 for actuating a thermoelectrically controlled safety device.

Referring first to Fig. 1, two transformers l and are indicated as having primary windings H and 2|, respectively, and secondary windings l2 and 22, respectively. The secondary windings l2 and 22 are connected in series to output leads including alternating current output terminals and 3|. The primary windings II and 2| are connected in parallel to alternating current input leads and 4| in circuit with any suitable source of alternating current. The secondary windings l2 and 22 of said transformers have such parameters that the voltages induced therein are equal or nearly equal in magnitude, and either the primary windings I I an l2| or the secondary windings l2 and 22 are so connected that the voltages induced in the secondary windings l2 and 22 oppose each other to the end that the net voltage output at the terminals an and 3| is zero or nearly so when both primaries are in circuit and are energized. In the form shown in Fig. 1 the primary windings H and 2| have opposite polarities as indicated by the arrows.

One of the parallel connections to the primaries H and 2| is provided with a normally closed switch 50, here shown as disposed in the lead ilg'iwhich connects one end of the primary 2lto one side 40 of the alternating current input circuit.

When alternating current is supplied to the leads lfl and H with switch closed, the output voltage at the terminals 30 and 3|. is zero or nearly so since the voltages in the: secondary windings l2. and 2.2 are equal and. of opposite.

polarity at every instant. Upon the occurrence of an abnormal condition such that switch 50 is opened, the primary winding 2| of transformer 20 is de-energized. I'hereupon the. voltage induced in the secondary winding 22 becomes zero, but the voltage available at the terminals 30 and 3| rises from zero to approximately the voltage induced in the. secondary winding I2. This alternating current output at the terminals 3|] and 31 may be utilized in any desired manner, the energy at these terminals becoming available upon opening the. switch. and unavailable as. lon as switchill is. closed. The same operation as Justdescribed would also occur if. there were a break in line 5| and therefore th switch 5|).is. to. betaken as typifying any causeiofopening, the linefih In Fig. 1 the connections betweenthe trans-- formers l0 and 24) are such that the secondary windings |2 andv 22 are: in series with additive polarities and the primary windings H and 21am connected to the alternating current input leads 40 and 4| so as to induce voltages of opposite polarity in the secondary windings l2 and 22. As before indicated, other arrangements of the connections of the transformers I0. and 201 may be employed, the only requirement being that the secondary windings I2 and 22 are connected in series and the primary windings H and 2| are connected in parallel under such conditions that when the transformers I0 and 20 are energized the voltage induced at the alternating current output terminals 30 and 3| is zero or approximately zero.

Figs. 2, 3 and 4 illustrate three different ways in which the voltage at output terminals 30 and 3| existing when the line 5| is opened, as by the switch 50, can be applied to a thermoelectrically controlled safety device to effect actuation thereof notwithstanding the continued generation of thermoelectric current.

Safety devices are now well known which include an electromagnet or solenoid for holdinga valve in open position, for example, as long as said electromagnet or solenoid is energized by thermoelectric current generated by a thermocouple subjected to the heat of a flame and operating on the principles disclosed in the patent granted to Sebastian Karrer, No. 2,097,838, on November 2, 1937. Upon failure of the source of thermoelectric current, however, the=electromagnet or solenoid is ole-energized so that the valve, in the illustration assumed, is closed. as by the.- action of gravity or a. spring, if theilame at the. thermocouple goes out. Conditions may arise, however, whereby it is desirable that the safety device closeeven though the flame at the thermocouple continues to generate normal thermoelec tric current. Figs. 2, 3 and 4 illustrate how this result may be obtained by use of the voltage (and. current) at the output terminals 30 and 3| when.- ever line 5| is opened.

Referring first to Fig. 2., thatportion of a safety device which includes a magnetic. core and an armature BI is shown schematically, said armature 6| being operatively connected in known de vices to any suitable valve, switch member, or: other member toLbe controlled (notshcwn). An. electromagnet winding 621 is provided on said. magnetic core 50 and is connected to athermcrscouple 6.3. Upon suflicient differential. heating. between the hot and coldjunctions of..said. themmocouple, the magnetic core 6|! is energized; tax.-

maintain armature 6| againstthe pole faces: 64: thereof, when armature '61 has been. moved 1mm. engagement with. said pole. faces, manually or any other suitable way. As. long as. electromag net winding 62-; is. so; energized, armature. 'Bil. is. therefore maintained. in the nusitioizrillustsaintly against gravity, or aspring or other fence, tenda ing to separate the. armature from the. pole" faces 64-.

In conformity with one embodiment of than present invention as shown schematically inl igz.

2, a second: electromagnet winding. 6511s provided. on the core 60 and connected to the terminalss 30' and 3 l which in turn are connected through: any suitable, lines. with the. output terminals 30; and 3| of Fig. 1. As long as the switch 50:01. Fig, 1 is closed and. the. alternating current output).

terminals 30 and supply a,- zero: or a negligible:

amount of electrical. energy to. winding. 65 through terminals 30!. and 3|, depending onrtha exactness with which the voltages of the secsondary windings l2 and. 22ers made to match each other, retention otthe armature 6|. initsi operative position as shown is solely under the control of the thermoelectric circuit 63, 62. Upon occurrence of an abnormal condition which would cause opening of the line 5|, as by opening the switch 50, the alternating current now available at the terminals 30 and 3| of Fig. l is applied through the terminals 30 and 3| to electromagnet winding 65 in Fig. 2. The magnetic field produced by electromagnet winding 65 will, with suitable alternating current flowing therein, cause the net magnetic flux of the electromagnet to fall periodically below that required to maintain armature 6| in the attracted position illustrated, thereby permitting armature 6| to move away from the pole faces 64 to actuate the associated safety device to inoperative position. Thus, opening switch 50 in response to an abnormal condition, or other opening of the line 5|, causes the safety device to move to its inoperative position even though normal thermo-electric current continues to flow in electromagnet winding 62.

Fig. 3 indicates schematically another application of the control device of Fig. l to a thermoelectrically controlled mechanism, like parts being indicated by like reference numerals. In this figure thermocouple 63 supplies energy to electromagnet winding 62 on core 6|], but one lead 65 between the thermocouple 63 and the winding 52 includes in series the secondary winding 12 of a transformer 10. Primary winding II of transformer is connected to terminals 30 and 3|, which in turn are connected in any suitable way to the output terminals 3|] and 3| of Fig. 1. Under normal operating conditions with the line 5| closed at 50, there is zero or negligible energy flow into primary winding II, and hence zero or a negligible alternating current is induced in the secondary winding 12. Under this condition the direct current generated at the thermocouple 63 energizes the electromagnet winding 62 to maintain armature 6| in contact with the pole faces 64, thereby maintaining the associated safety device in its operative position. Upon occurrence of an abnormal condition which opens the line 5|, as at 50, energy is Supplied to the output terminals 30 and 3| of Fig. 1, and flows through any suitable connections to the terminals 30' and 3| and through the primary winding H of transformer 70. This induces voltage in the secondary winding 12, causing an alternating current to be superimposed on the direct current generated by the thermocouple 63. and the resultant current now flows through electromagnet winding 62. With an alternating current component of suitable magnitude the magnetic flux produced by winding 62 will periodically fall below the minimum value necessary to maintain armature 6| in its attracted position, and armature 6| will therefore move to its inoperative position.

In the embodiment shown schematically in Fig. 4, the alternating current output from the terminals 30 and 3| of Fig. l is applied through the terminals 30' and 3|, respectively, to the thermocouple leads 65 and B6. As viewed from the terminals 30 and 3| thermocouple 63 and electromagnet winding 62 are connected in parallel. When llne 5| is closed at 5|] no alternating current or negligible alternating current is supplied to the terminals 30, 3|. Upon opening of the line 5|, as at 50, however, alternating current from the terminals 30 and 3| is applied to the terminals 30' and 3| and thence to the thermocouple leads 65' and 66. Part of this current flows through the thermocouple 63 and the remainder flows through the electromagnet winding 62, the net current flowing through the latter winding being the result of the superposition of the direct current produced by thermocouple 63 and the said remainder portion of the alternating current. With a suitable alternating current component flowing in the electromagnet winding 62, the magnetic flux will periodically pass through the minimum value required to maintain armature 6| in its attracted position, and armature 6| will thereupon move to its inoperative position.

To illustrate the actual operating characteristics of the device of Fig. 1 when used in the manner indicated schematically in Fig. 4 in controlling a commercial thermo-electric shutoff valve, similar transformers l0 and 20 were used, their secondary windings having a 60 cycle impedance of approximately 0.26 ohm. each. An input voltage of approximately volts, 60 cycles, was applied to the leads 40 and 4|, the voltage at each of the secondary windings l2 and 22, with switch 50 closed, being approximately 1.2 volts. With the output terminals 30 and 3| of Fig. 1 connected to the terminals 30 and 3| of Fig. 4, opening of the switch 50 increased the current through the terminals 3|) and 3| from zero to approximately 3.25 amperes. This alternating current superimposed on the direct current generated by the thermocouple 63, and which normally held the valve of the safety device in open position, was suflicient to cause the valve to close.

It will therefore be perceived that the present invention provides an electric device of simple construction which may be readily connected into existing as well as applied to new circuits and which as long as the control circuit is closed, generates substantially no voltage at the output terminals thereof, but upon a break in or other opening of the line including one of the primary windings, an impulse is generated at the output terminals which can be used to actuate electrical or electromagne'tically controlled devices. As applied to the actuation of thermoelectrically controlled devices, the alternating current at the output terminals 30 and 31 may be superimposed on the direct current generated by a heated thermocouple, or it may be applied to an electromagnet in circuit with the thermocouple, so that the net current value or the net magnetic flux will periodically pass through a predetermined minimum value and thereby cause the thermoelectrically controlled device to act as if the thermoelectric current had failed or decreased below a predetermined value even though thermoelectric current is still being generated normally.

While the embodiments of the invention illustrated on the drawings have been described with considerable particularity, it is to be expressly understood that such embodiments are for purposes of illustration only, and are not to be construed as definitions of the limits of the invention, as the invention may receive a variety of expressions, as will now be apparent to those skilled in the art, while changes may be made in the details of construction, arrangement, electrical parameters, etc., and parts may be replaced by equivalent parts, without departing from the spirit of this invention. Reference is therefore to be had to the appended claims for a definition of said invention.

What is claimed is:

1. In an electrical energizing means for a control device of the character including a thermoelectric circuit having therein a thermocouple accuser:

andian electromagneticmeans provtded armature operativeiy connected to amearrstc be:

controlled. and retaineduin operative position ba said electromagnetic means vvhiIeJncnmaithermoelectric current. is being: generaisd'v by said thermocouple, the combination of meanston tuating; said. electromagnetic means taemect re lease. of. said armature. notwithstanding cons tinued generationlof thermoeleclazic currentzcomeprising a control circuit includingoutputileads, input deads operatively connected to asource of: alternating current and meansinsaid control circuit having circuit connections to: input leads for imposing. substantially zero. voltagm across said output leads whenthe circuiticonnec tions from said meansito said input leads: are complete and operable. to impose. aasubstantiai voltage across said output. leads. upon interrup.-- tion of a line in said connections; and means electrically connected to saidoutput leads and; associated with said electromagnetic means; for applying alternating current insaid outputjeads to said electromagnetic means to reduce the' net efl'ect of said thermoelectric current-on said elect-- tromagnetic means sufliciently toweilect release of said armature.

2. In an electrical energizing meansior alcontrol device of the character including a thermoelectric circuit having therein a thermocouple and an electromagnetic means provided with a coil and an armature operatively connected to a means to be. controlled and retained in operative position by said electromagnetic means while normal thermoelectric current is being generated by said thermocouple, the combination. oifv means for actuatingsaid electromagnetic means to eflect release of said armature notwithstanding continued generation of thermoelectric current comprising a control circuitincluding output leads, input leads operatively connected to a source of alternating current and means in said' control circuit having circuit connections tosald. input leads for imposing substantiallyzero voltage across said output leads; when the circuitcom nections from said means tosaid input leads are complete and operable to impose a. substantial.

voltage across said output leads upon interruption of a line in said connections, and" means electrically connected. to saidroutputieads; and associated with said electromagnetic means for applying alternating current in said output; leads to said electromagnetic means to reduce the: net effect of said. thermoelectric current onsaid elecltromagnetlc means sufii'ciently' to efiectrelease of said armature, said last named meansinciuding a second coil associated with said electromagnetic means and. electrically; connected to said output leads and operable to decrease the net magnetic flux acting on saidarma-turewhen substantial voltageexists across-saidoutput leads.

3. In an electrical energizingv means for a control device of the character including a thermo-- electric circuit having therein a thermocouple and an electromagnetic means provided with an armature operatively connected to a means to be controlled and retained in operative position by said electromagnetic means while normaii thermoelectric current is being. generated by cmmections tcsaid .m utzleads; for inmosing sub stantially zero voltage. across. said output leads when the circuitconnections fromesaid means w said 'input' leadsare complete and operable tel-1m pose a" substantial voltage across said-011131111 leads-upon interruption of aline in said connec--- tions, and-means electrically connected to. soldioutput leads andassociated with said electrosmagnetic means for applyingalternating currents.

qgrin output leads to said electroma netic said thermocouple, the combination of means and means insaid. control circuit having circuit mean-s te reduce the net effect of said thermo electric current on said electromagnetic meansr sufliciently to effect release of said armature, said-last named means including a. transformer having a secondary in said thermoelectricc'irolliti' electric circuit having therein a thermocouple and an electromagnetic means provided with an armature operatively connected to a means to be controlled and retained in operative position by said-electromagnetic means while normalther m-oelectri'c current is being generated bysaid" thermocouple. the combination ofmeans for ac tuating said electromagnetic means to effect re lease of said armature notwithstanding continued generation of thermoelectric current com-'' prising a control circuit including output leads, input leads operatively connected to a sourceoi alternating current and means in said control circuit having circuit connections to said input" leads for imposing substantially zero volta e" across said output leads when the circuit con nections from said" means to said input leads are complete and operable to impose a substan tia-l voltage across said output leads uponinterruptlon of. a line in said connections, and means electrically connected to said output leads: and" associated with said electromagnetic means forapplying alternating currentin said output leads to said electromagnetic means to reduce the net effect of said thermoelectric current on said electromagnetic means sufficiently to effect release of said armature,- saidlastnamed mearcs" includingleads electrically connecting said output leads in parallel with said thermocoupleandelectromagnetic means.

5". Iiran electricai' energizing means for econ-- trol-device of the character including a thermo electric circuit having therein a thermocoupleand an electromagnetic means provided with an armature operatively' connected to a means to be" controlled and retained in operative position by said electromagnetic means while normal ther moeiectric current is being generated by" said thermocouple, the combination of means-for aotuating said electromagnetic means to efl'ect re-- lease of said armature notwithstanding contin ued generation" of thermoelectric current comprising a control circuit including output leads, input leads operatively connected to a source of" alternating current and a pair of transformershaving secondaries in series with said output leads and primarieshaving parallel connections with said input leads, said transformers being so constructed and connected to said leads that the additiveefiect of the current in said secondaries produces substantially zero voltage across said out-put leads when the circuits through both primaries are closed but operable to impose a substa-ntiai voltage across said output leads upon opening of the circuit through one of said primaries while the circuit through the other primary remains closed, and means electrically connected to said output leads and associated with said electromagnetic means for applying alternating current in said output leads to said electromagnetic means to reduce the net effect of said thermoelectric current on said electromagnetic means sumciently to effect release of said armature.

6. In an electrical energizing means for a control device of the character including a thermoelectric circuit having therein a thermocouple and an electromagnetic means provided with a coil and an armature operatively connected to a means to be controlled and retained in operative position by said electromagnetic means while normal thermoelectric current is being generated by said thermocouple, the combination of means for actuating said electromagnetic means to efiect release of said armature notwithstanding continued generation of thermoelectric current comprising a control circuit including output leads, input leads operatively connected to a source of alternating current and a pair of transformers having secondaries in series with said output leads and primaries having parallel connections with said input leads, said transformers being so constructed and connected to said leads that the additive effect of the current in said secondaries produces substantially zero voltage across said output leads when the circuits through both primaries are closed but operable to impose a substantial voltage across said output leads upon opening of the circuit through one of said primaries while the circuit through the other primary remains closed, and means electrically connected to said output leads and associated with said electromagnetic means for applying the alternating current in said output leads to said electromagnetic means to reduce the net effect of said thermoelectric current on said electromagnetic means sufliciently to eifect release of said armature, said last named means including a second coil associated with said electromagnetic means and electrically connected to said output leads and operable to descrease the net magnetic flux acting on said armature when substantial voltage exists across said output leads.

7. In an electrical energizing means for a control device of the character including a thermoelectric circuit having therein a thermocouple and an electromagnetic means provided with an armature operatively connected to a means to be controlled and retained in operative position by said electromagnetic means while normal theremoelectric current is being generated by said thermocouple, the combination of means for actuating said electromagnetic means to effect release of said armature notwithstanding continued generation of thermoelectric current comprising a control circuit including output leads, input leads operatively connected to a source of alternating current and a pair of transformers having secondaries in series with said output leads and primaries having parallel connections with said input leads, said transformers being so constructed and connected to said leads that the additive effect of the current in said secondaries produces substantially zero voltage across said output leads when the circuits through both primaries are closed but operable to impose a substantial voltage across said output leads upon opening of the circuit through one of said primaries while the circuit through the other primary remains closed, and means electrically connected to said output leads and associated with said electromagnetic means for applying the alternating current in said output leads to said electromagnetic means to reduce the net effect of said thermoelectric current on said electromagnetic means sufliciently to eifect release of said armature, said last named means including a, transformer having a secondary in said thermoelectric circuit and a primary electrically connected to said output leads.

8. In an electrical energizing means for a control device of the character including a thermoelectric circuit having therein a thermocouple and an electromagnetic means provided with an armature operatively connected to a means to be controlled and retained in operative position by said electromagnetic means while normal theremoelectric current is being generated by said thermocouple, the combination of means for actuating said electromagnetic means to effect release of said armature notwithstanding continued generation of thermoelectric current comprising a control circuit including output leads, input leads operatively connected to a source of alternating current and a pair of transformers having secondaries in series with said output leads and primaries having parallel connections with said input leads, said transformers being so constructed and connected to said leads that the additive eifect oi the current in said secondaries produces substantially zero voltage across said output leads when the circuits through both primaries are closed but operable to impose a substantial voltage across said output leads upon opening of the circuit through one of said primaries while the circuit through the other primary remains closed, and means associated with said electromagnetic means for applying the alternating current in said output leads to said electromagnetic means to reduce the net effect of said thermoelectric current on said electromagnetic means sufficiently to effect release of said armature, said last named means including means electrically connecting said output leads in parallel with said thermocouple and electromagnetic means.

PAUL L. BE'IZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,539,658 Fitzgerald May 26, 1925 2,241,127 Harder May 6, 1941 2,306,578 Wetzel Dec. 29, 1942 2,351,277 Mantz June 13, 1944 2,428,747 Ziebolz Oct. 7, 1947

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