US2005584A - Temperature controlling device - Google Patents

Description

June 18, 1935.

A. H. HEYROTH TEMPERATURE CONTROLLING DEVICE Filed Jan. 27, 1932 2 Sheets-Sheet 1 F511 is INVENTOR ALBERT H. HEYROTH ATTORNEY June 18, 1935. A H, EY TH 2,005,584

TEMPERATURE CONTROLLING DEVICE Filed Jan. 2'7, 1932 2 Sheets-Sheet 2 Z INVENTOR ALBERT H. HEYROTH BY W0 ATTORNEY Patented June 18, 1935 UNITED STATES 2,005,584 TEMPERATURE CONTROLLING DEVICE Albert H. Heyroth, Niagara Falls, N. Y., assignor to Globar Corporation, Niagara Falls, N. Y.

Application January 27,1932, Serial No. 589,177

6 Claims.

The invention relates to an electric current control system whereby the ratio of the alt to the on periods may be varied to control the energy in the heat producing apparatus.

The invention is particularly adapted for the heat regulation in electric household appliances and will be explained for such use.

The ordinary arrangement for controlling temperature in electric heating appliances is by means of a plurality of circuits which are switched into various combinations as series, series parallel, or parallel. Such a system limits the number of temperatures possible with a resulting uneconomical operation of the heating appliance.

An object of this invention is to provide a flexible temperature controller for heat producing apparatus by including in the main circuit of the apparatus a make and break switch controlled by a thermo-responsive device. The present invention relates to improvements in a control device of this kind and essentially consists in a particular physical arrangement having certain practical advantages.

The invention will be more fully described with reference to the accompanying drawings:

Figure 1 is a bottom plan view of a control switch constructed in accordance with the present invention;

Figure 2 is an elevation of my control mechanism looking in the direction of the arrow A of Figure 1, the adjacent face of the casing and the upper part of the frame being removed;

Figure 3 is a view taken in the direction of the arrow B of Figure 1, the adjacent part of the casing being removed; v

Figure 4 is a view taken in the direction of the arrow C of Figure 1, the adjacent part of the casing being removed;

Figure 5 is a schematic circuit diagram of the temperature control system of this invention;

Figure 6 is a plan view of the rear of the control rheostat;

Figure 7 is a plan view of the frontof the control rheostat;

Figure 8 is a section of the control rheostat;

Figure 9 is a conventional view of the control panel; and

Figure 10 illustrates a method of mounting the control rheostat of Figure 8.

To facilitate an understanding of the mechanism illustratedin Figures 1-4, 6-9 and of the manner in which it operates, I will first follow the schematic circuit as shown in Figure 5-.

The reference characters I, 2, 3, 4 designatethe outlet points of the switching mechanism which is enclosed within case 22, Figure 2. The reference character 5 of Figure 5 indicates the controlled appliance. The reference characters 8 and I5 designate the power leads. The contacts 6, l and 2| are incorporated in the control rheo- 5 stat shown in Figures'l, 8 and 9.

The operation of my invention is as follows:

When the contact arm 6 is moved from the off position (shown in the schematic circuit diagram of Figure 5) to the position marked 10 low or anywhere between the position marked low and the position marked high, points I and 2 will be connected through contact arm 6 and rail 1. The current will then flow from the service line 8 through point 3, heating coil 9', 15 point 2, contact arm 6, rail 1, point I, bimetal thermostat element II), contact II, wire I2, solenoid I3, wire I4, point 4, through element 5 to the service line I5. Since the winding of the solenoid I3 has a relatively very high ohmic re- 20 sistance, the current is limited to a very small value and does not, at this stage, serve any purpose with respect to the controlled appliance 5. It is suflicient, however, to energize solenoid I3 and to cause it to draw contact arm I6 into elec- 25 trical contact with contact I! against the compression of spring I8. In doing so, the operation of the mechanism is such that contact I6 does not engage contact I1 until after I6 has passed the latching position with respect to latch I9. 30 The engagement of I6 and I 1 short circuits the winding of solenoid I3 in that it joins wire I4 (one terminal of the solenoid winding) to wire I2 (the other terminal of the solenoid winding) by means of the following connections: lead wire 35 I4, contact I'I-I6, wire 20, point 2, contact arm 6, rail I, point I, bimetal I0, contact H, and lead wire I2. The current in the solenoid I3 is thereby diminished and the spring I8 will tend to carry contact arm I6 to its initial position. However, since I6 has been carried beyond the latching position with respect to I9, as stated above, I6 can only make a slight return movement before it is stopped by its engagement with the latch on arm I9. It is to be noted that the mech- 45 anism is so constructed that the contact between I! and I6 is not lost during this movement. Contacts I6 and I! not only serve to deenergize solenoid I3 as described, but also constitute the main switch contacts with respect to appliance 5. The 50 operating current for appliance 5 will now flow through the system as follows: service line 8, point 3, heating coil 9, wire ZIL-contact I6-I1, wire I4, point 4, appliance 5 and service line I5.

It is assumed at this state that the contact 55 arm 6 is at the position designated as low, in which position contact between 6 and l is established, but contact between 8 and 2i is open. At this setting of contact arm 5 all of the current flowing through controlled appliance 5 will pass through the heating coil 9. Heating coil a is therefore now at its highest heating effective ness. The heating coil 9 is in such a position with respect to the bimetal ill that a maximum amount of energy radiated from. heating coil :3 will be absorbed by the material of bimetal ill. It is to be noted that the heating coil 9 may be of such resistance as to be no appreciable factor in the overall resistance of this circuit. Moreover, the energy dissipated by heating coil 9 at this stage is so low in value that it constitutes a negligible loss with respect to the capacity of the controlled appliance 5. The function of the heating coil 9 is to warm the bimetal l and cause it to flex in the direction indicated by the dotted line immediately above, which dotted line designates the unlatching position. The bimetal l l in flexing opens the contact between ill and M. It is to be noted that contacts ill and ii are in a branch short line containing the solenoid 93 by virtue of the engagement of i6 and ill. Therefore, very little current is flowing through the solenoid and no spark will result from the opening of contact in and l l through the flexing of bimetal ill. The flexing of bimetal ill through its mechanical engagement with latch ill will tend to raise 99 to the unlatching position. At the unlatching position, the contact arm i6 is released from its engagement with latch l9 thereby permitting the spring IE to return contact arm is to its initial position out of engagement with contact ii, the contact lS-ll being, as stated above, the main switch contact with respect to the controlled appliance 5, the opening of contact Iii-ll opens the operating circuit of appliance 5.

The sequence of events just described may be designated as those taking place during the on period of appliance 5. Hence, during the time required to flex bimetal Hi from its contact position with respect to H, to its unlatching position with respect to arm IS, the appliance has been receiving energy at its full rated capacity; that is, appliance 5 has been directly across service lines 8-l5.

The sequence of events now to be described may be designated as the oil period with respect to appliance 5, since during this period the contacts l6l'l are out of engagement and the appliance 5 is in open circuit position.

The contacts l6l'l being open, heating coil 9, as well as appliance 5, is deprived of current. The bimetal l0 istherefore free to cool and return from the flexed or unlatching position to its normal position in engagement with contact II.

The off period with respect to appliance 5.

therefore, embraces the interval of time required for bimetal Ill to return from the unlatching or flexed position to its normal contacting position with respect to II.

Figures 2 and 3 show the application of my invention in a commercial form. The same numbers for designating corresponding parts are used in these figures as are used in the schematic circuit diagram Figure 5.

The drawings show the manner of housing by means of the shell 22. The prongs I, 2, 3, 4 which extend through the housing correspond to points I, 2, 3, 4 on the schematic diagram. To render it impossible to plug the assembly into a socket in any but the correct manner, one of the four prongs is made smaller in diameter than the other three. Another method of accomplishing the same result is by disposing them asymmetrically so that they can only be inserted into the holes of the socket in the correct manner.

The frame 23 is a sheet iron stamping which forms a magnetic yoke around the solenoid it, and its extensions above the solenoid it serve as the mounting frame or support for the bimetal iii, contact arm it, latch i9, contact ii, and also provide support for springs i tl8 and the guide slots for stamping 26, which carries the solenoid plunger 26. The frame "23 also provides an anvil within the solenoid in that a button Si is formed on its lower cross member, which button forms a plug which extends upward into winding l? and toward which plunger 26 is drawn when the solenoid i3 is energized. ihis button or anvil Si is indicated in dotted lines in Figure 2 of the drawings.

The assembly ll-2 l-2526 constitutes the moving element of the switch. is an iron plunger, one end of which projects slightly into the solenoid it, as shown in Figure 2 of the drawings, and to the other end of which is fastened the stamping Referring to Figure 4 of the drawings, the stamping 2&1 is shaped so that its lower cross member extends through the guide slots in 23 and is provided with a hole at each end. These holes serve as eyelets in which springs lt-HSA are hooked.

The stamping 2 5 carries on its upper cross member the main switch contact it which is insulated from 2 1 by means of insulating shim 25. The slot between the upper and lower cross arms of 2d guides the contact arm it, which is actuated by the movement of 24. The latching member of the contact arm 96 extends from the hinge pin of it through the slot between the upper and lower cross arms of 24, as shown in Figure 2 of the drawings.

The operation of the switch mechanism is as follows: when the winding I3 is energized by the manual movement of the control (see Figure 3) from off to low, the plunger 26 is drawn downward toward the anvil 3| formed at 23 and situated within the lower end of the solenoid l3. The plunger 26 carries with it the members 24. 25, I1, thereby stretching the springs l8, |8A which connect the stationary frame 23 and moving element 24. Since the contact I! is part of the assembly I1, 24, 25, 26, it will follow the straight line downward movement of 26. cross-arm member 24 moves downward, it engages the latching member of contact l6 causing it to rotate on its hinge pin 32. This movement brings the contacts l6 and I1 into engagement. Through the closing of contacts I 6 and H, the solenoid I3 is deenergized. and with the opening of the contact H by the flexing of the bi-metal away from its contacting position, the solenoid circuit becomes disconnected. As no curre t flows through the solenoid during the on period after the closing of the main switch, the plunger 26 can eventually return to its initial position when permitted by the member l9. After a slight movement in this direction, the latching member of contact l6 encounters the latch I 9 which stops further movement. Here it remains until bimetal IO has been heated sufficiently to flex it outwardly, whereupon the latching member of contact I6 is released from engagement with IS.

As the The springs |8--|8A are then free to return the assembly I1, 24, 25, 26 to its initial open position.

The last phase of the operating cycle is the time interval required for the bimetal III to return from its flexed (or unlatching) position, back to its contacting position with respect to contact I.

In order to explain the manner in which any temperature control may be obtained in the heating appliance, reference to Figures 6, 7, 8, 9 and 10 will be necessary.

A complete control is effected through the movement of contact arm 6 from the off position to the high position or vice versa. Referring to Figure 5, it is obvious that, as the outer end of the arm 6 is moved along the slide wire resistance 2| toward the high position, the part of the total current (from the line wire 8) which flows through the resistance 2| will increase, and that the part which flows through the heating coil 9 will decrease.- Hence, the movement of the contact arm 6 toward the high position has the efiect of increasing the on interval of the appliance 5 within the operating cycle with a consequent increase of the resultant temperature of the appliance 5. Incidentally, during the movement of the contact arm 6, the oil period of the operating cycle is shortened for the reason that the diminishing radiation from the heating coil 9 diminishes the tendency to move the bimetal III to the unlatching position. Hence, the on period is increased and the of! period decreased. A co'nverse effect is produced by moving 6 toward the ofi position. It is tobe noted that the range of control with respect to appliance 5 includes the two extremes--off position and high position. At the off position the solenoid I3 is inoperative in its open circuit position (|6 being open) due to the interruption of its circuit at the contact 6'|. The appliance 5 therefore remains definitely inoperative as long as the contact arm 6 is in the off position. At the other extreme, when contact arm 6 is in the high position, solenoid I3 is inoperative in its closed circuit position (|6|'I being closed) due to the fact that its winding is short circuited by the engagement of |6|1. At this position of contact arm 6, the engagement of IS with IT is maintained because bimetal H], as described above, will not actuate latch l9 due to the short circuiting of heat coil 9. It is evident that the contact arm 6 may be adjusted between these extremes to a position which will efiect the required resultant temperature of appliance 5. It is also evident that the assembly comprising 6, 1 and 2| is exceedingly simple and inexpensive and that this assembly may be remote from the switching mechanism enclosed in the dotted line.

For example, just as appliance 5 may be remote from the balance of the circuit by lengthening the lead from it to point 4 as required, the assembly 6, I, 2| may be remote from the switching mechanism proper by lengthening, to the required degree, its leads to points 2 and 3. I

In the particular mechanism, as for example devised for operation with domestic electric ranges, 6, 1, 2| are mounted on an insulating disc 2 in diameter and A" thick. This assembly is mounted in the rear of the range switch panel with the shaft of arm 6 extending through the panel and terminating in front of the panel in a knob with an index finger similar to the knobs employed in volume control rheostats in radio practice. The front of the panel Figure 9 is marked high, low and off and has a series of calibration marks between the low position and the high position so that the operator can readily set the index finger of the knob in the position required for the purpose at hand.

I claim:

1. A system for varying the ratio of the on and off periods of an intermittently operated electrical device, comprising in combination an electromagnetic switch actuated in one direction by a solenoid and in the reverse direction by mechanical means, holding means for preventing the return movement of the switch after it has been actuated by the solenoid, a mechanical release means adapted to disengage the said holding means, a thermoresponsive element operating between two positions, the thermoresponsive element in one of the said positions making an electrical contact which closes the solenoid circuit and in the other of the said positions actuating the mechanical release to permit the automatic opening of the switch, a shunt circuit by-passing at least a portion of the current around the solenoid when the said switch is closed, means for applying heat to the thermoresponsive element in repetitive cycles dependent upon the on and ofi positions of the switch, and means for varying the rate of heat supply to the thermoresponsive element.

2. In a mechanism for controlling the on and ofi periods of an electrical device, a magnetic switch actuated by a solenoid, holding means for retaining the said switch in closed position, a mechanical release'means which permits the mechanical opening of the switch, mechanical means for opening the switch when the release is actuated, a bi-metal strip operating between two positions, the bi-metal strip in one of the said positions making an electrical contact which closes the solenoid circuit and in the other 'of the said positions actuating the said release, a shunt circuit closed by the said switch, the said shunt circuit passing through the bi-metal contact and deenergizing the solenoid when the bi-metal contact and the switch are closed, and a second shunt circuit also closed by the said switch which contains a heating element for the bi-metal strip and which by-passes the current around the contact made by the bi-metal strip when the said contact is open and the magnetic switch is closed.

3. In a mechanism for controlling the on and off periods of an intermittently operated electrical device, a magnetic switch actuated by a solenoid, a. holding means adapted to maintain the switch in a closed position, a spring adapted to open the switch when the said holding means is disengaged, a bi-metal strip operating between two positions, the bi-metal strip in one of the said positions making an electrical contact which closes the solenoid circuit and in the other of the said positions disengaging the said holding means, an electric heating element in close proximity to the bi-metal strip and adapted to impart heat thereto, a circuit for the said heating element which is alternately opened and closed with the opening and closing of the said switch, and a shunt circuit closed by the said switch, the shunt circuit by-passing the current around the solenoid and de-energizing the solenoid when the' circuit for the device being controlled is closed. 4. The combination described in claim 3, in which the contact closing the solenoid circuit is rigidly attached to the bi-metal strip.

5. The combination described in claim 3, in

which a shunt circuit also by-passes the current around the contact closed by the bi-metal strip when the solenoid circuit is closed.

6. In a mechanism for controlling the on and 01? periods of an intermittently operated electrical device, a solenoid, a plunger actuated by the solenoid, a contact carried by the plunger and adapted to close the electrical circuit of the device being controlled, mechanical holding means for maintaining the plunger in a fixed position after actuation of the solenoid, mechanical means for moving the plunger in a direction opposite to the direction of movement produced by the solenoid when the said holding means is disengaged,

a bi-metal strip operating between two positions,

aooasee the bi-metal strip in one of the said positions making an electrical contact which closes the solenoid circuit and in the other of the said positions disengaging the said holding means, an electric heating element in close proximity to the bi-metal strip and adapted to impart heat thereto, a circuit for the said heating element which is alternately opened and closed with the opening and closing of the said switch, and a shunt circuit closed by the said switch, the said shunt circuit by-passing the current around the solenoid and de-energizing the solenoid when the circuit for the device being controlled is closed.

ALBERT H. .HTEYROTH.

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