US2572162A - Sheetsxsheet i - Google Patents

Description

Oct. 23, 1951 J. c. KOONZ THERMOELECTRIC TIMER MOTOR 2 SHEETS-SHEET 1 Filed March 8, 1947 1951 J. c. KOONZ THERMOELECTRIC TIMER MOTOR 2 SHEETSSHEET 2 Filed March 8', 1947 Patented Oct. 23, 1951 THERMQELECTRIC TIMER MOTOR John C. Koonz, Fort Wayne, lnd., assignor to The Magnavox Company, Fort Wayne, Ind., a

corporation of Delaware Application March 8, 1947, Serial No. 733,411

3 Claims. 1

The present invention relates to timing devices for intermittently performing a control function or sequence of control functions, Devices of this class are employed in washing machines for periodically closing electrical circuits which in turn control electromagnetic devices governing the intake and drainage of water. They are also used in a wide variety of other industrial, commercial laboratory and domestic applications to electrical equipment, wherever a circuit must be closed or opened at a predetermined time or whenever one circuit must be closed or opened at a predetermined time following the application of power to another circuit, for example.

Typical of the prior art are the rotary timer employed in internal combustion engines and the various modifications of that timer. Such a timer consists of a series of contacts, a rotating contact arm, and a motor for driving the arm whereby the arm touches the contacts in sequence and closes various circuits associated with them. This device has been found adequate for high-speed operation when each circuit is closed hundreds of times each minute but is not suitable for slow-speed operation even when reduction gearing is provided. Such gearing renders the continuously motor-driven type of timer expensive, complex and ineflicient, especially when the control functions to be performed are time-spaced by periods of several seconds, for example. These limitations are aggravated when the particular application requires adjustment or variation of the timer speed or time-spacing between control functions.

Electronic timers have been developed in an effort to provide a suitable timer for slow-speed or intermittent operation. They are premised on the vacuum tube which not only requires a spacecurrent source and suitable sources of heating current and biasing potential-but also is inherently delicate and subject to frequent replacement.

In the operation of certain machines, such as domestic washing machines of the automatic type, it is desired to provide a relatively simple, inexpensive and yet reliable timing device for controlling the sequence operation mechanism. The sequence operation mechanism controls electrically actuated valves which govern the intake and drainage of cleaning fluid or water. The sequential operations performed by the mechanism are spaced apart by substantial intervals of time.

In the past attempts have been made to use an electric clock motor for this purpose, but such 2 arrangements are relatively expensive. In some cases mechanically-wound clock mechanisms have been employed, but such arrangements have been found to be unsatisfactory since they frequently require service due to the effects of humidity and temperature.

It is therefore an important object of the present invention to provide an improved electrical timing device which is relatively simple, economical and reliable in operation.

The primary object of the present invention is to provide an impulse-operated, variable-speed timer for intermittently performing circuit-control functions.

Another object is to provide a timer characterized by efficiency, simplicity, low operating cost, reliability and a minimum of parts.

A further object is to provide a timer having a simple variable-speed adjustment.

Other and further objects and advantages of the present invention subsequently will become apparent by reference to the following description taken in conjunction with the accompanying drawings, wherein there is shown an illustrative timer in accordance with the invention.

In the drawings: Fig. 1 is a schematic and perspective view of a variable-speed timer in accordance with the present invention. Figs. 2, 4, 5, 6 and 8 are sectional views taken on line 2-2 of Fig. 1, line H of Fig. 3, line 55 of Fig. 2, line 8--6 of Fig. 2, and line 8-8 of Fig. 2, respectively; Fig. 3 is a sectional view of the bimetallic element and pawl mounting; and Fig. 7 shows an arrangement of cam switches suitable for use with the Fig. 1 embodiment.

Referring now to Fig. 1 there is shown a suitably mounted shaft ll carrying for rotation three insulated contact carriers I2, l3 and N of three rotary switches. Mounted on each carrier are a peripheral contact l5, Hi or H and a conductive segment l8, I9 or 20. Each conductive segment is integrally connected to its associated peripheral contact, as shown at 2|. Spring contacts 22, 23, 24 continuously bear on contacts 15, i6 and I1 and spring contacts 25, 26 and 21 bear intermittently on segments l8, l9 and 20 as shaft ll rotates, closing and opening circuits 28-28, 303l, and ill-33 in order. These switches are here shown for the purpose of illustrating one control function for which the invention is suitable. The invention is capable of performing many other control functions.

In accordance with one of the important features of the invention, there is mounted on posts 3|, 35, 36, 31 a dished bimetallic element 38 initied and integrally formed of layers of suitable thermoacting dissimilar materials or metals havin difierent linear coefilcients of thermal expansion such as stainless steel or bass, for example. Such a member is generally referred to as a bimetallic element. Such elements are used in. Klixon switches, for example. I employ this element to perform the timing effect.

In order to secure the bimetallic element to the post and at the same time to provide for flexure four semi-circular notches 48 (Fig. 8) are formed in the bimetallic element and spaced in quadrature and the posts are formed with annular grooves 48 (Fig. 2). The edges of the notches are disposed within these grooves, whereby the bimetallic element is secured against undesired angular and linear displacements without interference with its desired flexure.

The bimetallic member is intermittently heated by electric currents flowing through a resistor 42. This resistor is generally circular in shape and is helically wound. It has a lead 43 which projects through an insulating base 44 and is soldered to a terminal 45. It is also provided with a rotary contact arm 46 mounted for rotation by a screw tl, projecting through a collar 48. Lock nut 49 is carried by the threads on screw 41 in order to secure contact arm 46 in any desired angular position. Disposed between the lock nut and the collar is a terminal 50. The terminals 45, 50 are coupled to a suitable source of heating current (not shown), terminal 50 being connected to the source through contacts 13, 14 for a purpose hereinbelow explained. This variable resistor performs an important function in varying the periodicity of the timing, as will hereinafter be pointed out.

The insulating base 44 also provides support f :r the metallic posts 34, as, 36 and 31, the latter being screwed into the base or otherwise suitably secured thereto.

The bimetallic element is used to actuate a pawl-and-ratchet mechanism, which is employed to turn shaft i l.

Secured to the bimetallic element 38 is a pawlmounting member 52. This member comprises an integral upstanding lug 53 and an integral base. The base is formed with spaced upper and lower flanges 54 and 55 and an intermediate re-' advantage that the ratchet wheel may be removed and replaced by another wheel having a greater or lesser number of teeth. This provides a second adjustment means cooperating with the firstxnentioned adjustment means whereby the periodicity of the device may be varied, as desired.

1 also provide means for causing successive impulses to be generated. The circuit from the source to terminal 50 passes through a pair of contacts 73, I4. suitably insulated and mounted on the top end of post 34. These contacts are normally closed. Contact 13 is carried by a. spring blade '55 which, when pawl 65 moves upwardly, is forced upwardly by a projection on the pawl, breaking the circuit between contacts 13 and I4 and deenergizing the resistor 42.

In order to achieve uniformity of cyclical operation there is provided, in accordance with another feature of the invention, a heat storage function. Specifically, a mica diaphragm 16. having a central opening 1! is interposed between the heater 42 and the bimetallic element 38. This diaphragm is preferably secured in position by slots on the posts 343l. Diaphragm l6 acts as a heat insulator which prevents the bimetallic element 38 from absorbing heat directly from the heating element. The rate of heat absorption by element 38 is decreased compared to that rate if diaphragm 16 were absent. Because of this lower rate of absorption of heat, heating element 42 necessarily heats to a higher temperature than it would in the absence of diaphragm 15. Therefore, heating element 42 stores more heat than it would in the absence of diaphragm I6 and radiates heat to the bimetallic element for a longer period of time after contacts 13 and 14 are opened than would be the case if diaphragm I5 were absent. The diaphragm 16 also intercepts the flow of heated air to bimetallic element 38 so that heat conducted by air from heater 42 is delayed and the temperature of the air flowing through aperture H is higher than would be the case if diaphragm 16 wereabsent. The temperature of the surrounding structure is also increased as a result of the higher temperature of the heating element-42 so that the overall effect of diaphragm I6 is to prolong. the effective heating period during which bimetallic element 38 is flexed into its dotted line position. The result is that when small changes in line voltage occur,

7 the cycle of operation is leveled off to compenin the bimetallic element through which the recures the pawl mounting in place with respect to the bimetallic element and at the same time permits flexure of the bimetallic element.

Pivotally mounted on the pawl mounting 52 by a pin 64 is a pawl 55, formed with bifurcations embracing the upstanding lug 53. The other end of pawl 65 engages a tooth on a ratchet wheel 66. The ratchet wheel is secured to a screwtt readed extension 81 of shaft l I by a nut 68 and a key 69. A pawl 10 prevents undesired rotation of wheel 66 in a reverse direction. The wheel is driven in the desired direction by upward movement of pawl 85, in response to the generation of impulses by the bimetallic element. The ends of a tension spring II are secured to pawl 65 and post 36 to keep the pawl in engagement with the ratchet wheel.

"duced portion 56 of the pawl-mounting projects. This construction has the advantage that it seevents occur. Bimetallic element 38 is heated sate for these small changes. Additionally, fluctuations in heat from the heater are smoothed out, so that the heat is uniformly and consistently applied to the bimetallic element-during correspending portions of successive cycles. ,By pro vid ng this diaphragm I have been able to render the periodicity of the timing operation percise and uniform.

During each cycle of operation the following and upon attaining a critical degree of heat and at a predetermined time it snaps from the normal contour shown in full lines in Fig. 2 to the position shown in dashed lines, raising pawl 55 and ment is employed to perform the basic timing function by periodically generating mechanical impulses.

After the contacts l3. T4 are broken and at a predetermined time the bimetallic element snaps back to the full-line position shown in Fig. 2 and places the pawl in the position of readiness to turn wheel 66 when the next mechanical impulse is generated. It will be seen that in accordance with this invention I not only use a bimetallic element to generate an impulse, but I also use it to open a switch and to disable the heater that causes the bimetallic element to generate the impulse.

When the bimetallic element snaps back to its normal position the contacts 13, 14 again close and the resistor is again energized, with the result that the cycle is repeated.

In accordance with still another feature of the invention I vary the amount of heat applied to the bimetallic element and accordingly vary the periodicity of the cycle by adjusting the position of contact arm 46 on resistor 42. Further adjustment is provided by the combination of the rheostat and the interchangeable ratchet wheel 66. Thus it will be seen that I have provided a timer which will satisfy wide ranges of timin requirements, and possesses the advantages of simplicity and reliability.

In Fig. 7 there is illustrated a suitable arrangement of cam-actuated switches suitable for use with my timer. Suitable cams may be mounted on shaft II and employed to close spring-blade switch contacts in sequence.

While there has been shown and described what is at present considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and substitutions of equivalents may be made without departing from the true scope of the invention and it is, accordingly, intended in the appended claims to cover all such changes and modifications as fall within the true and proper scope of the invention and to obtain protection appropriate to my contribution to the art.

Having thus described my invention, I claim:

1. A thermally actuated timing device comprising a dish-shaped snap-impulse bimetallic operating element, a radiant heater for supplying heat to said element positioned in proximity to said element but spaced therefrom with a substantial air gap therebetween, switch means in operative relation to said element and connected to and heater, said heater being energized when llld switch means is in closed position, said ele ment being adapted when heated a sufiicient amount to snap to a flexed position to open said switch means and thereby deenergize said heater, heat insulating means positioned in said air gap and spaced from said element and said heater, said last named means serving to trap heat and prolong heating of said element after said heater is deenergized to hold said element in said flexed position a predetermined time after said heater is deenergized, said insulating means comprising an insulating battle having an opening therein.

2. In a heat motor, in combination. a preformed dish-shaped bimetallic element, a radiant heater for supplying heat to said element positioned in proximity to said element but spaced therefrom with a substantial air gap tlierebetween, means for adjusting said heater to vary the amount of heat supplied to said element, switch means operatively associated with said heater and said element, said heater being energized when said switch means is in closed position, said element being adapted when heated a sufficient amount to snap to a flexed position to open said switch means and thereby deenergize said heater, thermal delay means consisting of an insulating baille positioned in said air gap in spaced relation to said element and said heater, said last named means serving to trap heat and prolong heating of said element after said heater is deenergized to hold said element in said flexed position a predetermined time after said heater is deenergized.

3. In combination, a pawl and ratchet mechanism, a bimetallic element having a self-displaceable portion for actuating said mechanism, adjustable heater means for heating said element to cause self-displacement of said portion, switch means normally to energize said heater and to deenergize said heater means upon displacement of said portion and means to retain said portion in its displaced position for a predetermined time after said heater means is deenergized, said last named means comprising a heat insulating diaphragm having an opening therein positioned between said portion and said heater means.

JOHN C. KOONZ.

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

UNITED STATES PATENTS Number Name Date 1,215,665 Landis Feb. 13, 1917 1,225,887 Swan May 15, 1917 1,492 459 Gregory Apr. 29, 1924 1,576,649 Gregory Mar. 6, 1926 1,661,103 Appelberg Feb. 28, 1928 1,852,261 Piatt Apr. 5, 1932 1,881,884 Noble Oct. 11, 1932 1,980,756 Hoover Nov. 13, 1934 2,066,145 Fink et al. Dec. 29, 1936 2,090,619 Biach et al Aug. 24, 193 2,137,507 Ostline Nov. 22, 1938 2,203,719 Crane June 11, 1940 2,347,014 Willmann Apr. 18, 1944 2,361,193 Gray Oct. 24, 1944 2,414 531 Johns Jan. 21, 1947 2,468,996 Olsen May 3, 1949 2,471,924 Bolesky May 31, 1949 2,473,233 Short June 7, 1949 FOREIGN PATENTS Number Country Date 412,082 Great Britain June 21, 1934 Certificate of Correction Patent No. 2,572,162 October 23, 1951 JOHN C. KOONZ It is hereby certified that error appears in the printed specification of the above numbered patent requiring mrrection as follows:

Column 3, line 4, for bass read brass; line 40, for into read onto; column 4, line 59, for perclse read precise; column 5, line 13, for causes read caused;

and that the said Letters Patent should be read as corrected above, so the; the same may conform to the record 01' the case in the Patent Ofliee.

Signed and sealed this 12th day of February, A. D. 1952.

THOMAS F. MURPHY,

Aau'stant Commissioner of Patents.

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