US2979580A - Electric switches - Google Patents

Description

April 11, 1961 Filed June 4, 1959 P. W. TlMM ETAL ELECTRIC SWITCHES 4 Sheets-Sheet 1 Fue. Z.

INVENTORS Y Roeea D. RuLseH A-rwoauav April 11, 1961 P. w. TlMM ETAL 2,979,580

ELECTRIC SWITCHES Filed June 4, 1959 4 Sheets-Sheet 2 Fla. 5

l9 2 3o- 38 v INVENTORS Paul. W. T\ MM BY Roeaa D. RULSEFL ATTORNEY April 11, 1961 Filed June 4, 1959 P. W. TIMM ETI' AL ELECTRIC SWITCHES 4 Sheets-Sheet 5 INVENTORS '7 Paul. \N.T\MM

ROGER D. RuLsEH BY m flz/rngw AT-rcniu Y April 11, 1961 P. w. TIMM ETAL 2,979,580

ELECTRIC SWITCHES Filed June 4, 1959 4 Sheets-Sheet 4 CT 9 m I l INVENTORS A-r-roauav United States Patent .0

ELECTRIC SWITCHES Paul W. Timm, Manitowoc, and Roger D. Rulseh, Two

Rivers, Wis., assignors, by mesne assignments, to American Machine & Foundry Company, New York, N.Y., a corporation of New Jersey Filed June '4, 1959, Ser. No. 818,142

2 Claims. (Cl. 200-38) This invention relates to electric switches.

Objects of this invention are to provide a novel form of electric switch which is so arranged that there is a power contact through which power is selectively supplied to two other contacts constituting a first circuit and a second circuit contact, and in which means are provided in the form of a cam construction driven by a synchronous motor so that at periodic intervals, a change is made in the contacts so that the power contact is placed in contact with the second circuit controlling contact and disconnected from the first circuit contact and in which continued motion of the cam means will restore the switch to its initial position with the power contact in engagement with the first circuit contact, and in which means are provided whereby the cam means itself is shifted so as to disconnect the power contact from the second circuit contact and restore it instantaneously to the first circuit contact.

The electric switch is capable of use in a great many installations and is not to be limited to any particular use. However, for the purpose of illustration, it can be very expeditiously used in connection with defrosting systems for a refrigerator. For example, the switch could be used in the defrosting system in which there is a power circuit and a compressor circuit normally connected, and in which the cam is arranged to disconnect the compressor or first circuit contact from the power contact and connect the power contact to the second circuit contact or heater contact and in which electromagnetic means are provided for instantaneously changing back from the heater contact to the compressor contact when the temperature within the refrigerator has arrived at a predetermined value and defrosting is therefore complete.

This arrangement described immediately above is shown in the copending application of Joseph J. Everard, Serial No. 613,186,for Control Means'for Defrosting Refrigerators, filed October 1, 1956, now Patent Number 2,975,612 of March 21, 1961, and assigned to the same assignee as the present application. Although it is to be distinctly understood that the switches'forming' the subject matter of this invention are not confined or limited to such use. This could be used in many other types of installations, forexample, a hot air defrosting system or other systems, or for electric signs or other systems of a type where a switch of this order would be useful.

Further objects are to provide a construction in which cammeans are provided to initiate the switching operation from .a power contact to a first circuit contact over to a second circuit contact for energizing the second circuit and disconnect the power supply from the first cir cult and connect it to the secondcircuit, and in which electromagnetic means are provided for instantaneously transferring the contacts back to 'th'eir initial position, 1

as set forth hereinabove, by shifting the cam means itself. if

Further objects are to provide a construction as set forth hereinabove in which electromagnetic meansare 'Z,979,580 Patented Apr. 11, 1961 employed and used only instantaneously to shift the cam means itself and to thereby re-establish the initial position of the contacts, and in which the electromagnetic means is so associated with the switch contacts that the electromagnetic means is instantly cut off after it has performed its function of shifting the cam means itself and efiecting re-establishment of the contacts in their initial position.

A further specific object of this invention is to provide a construction in which each of the switch elements of the structure is formed and mounted and associated with the other elements of the switch structure, so as to secure a wiping contact whenever the switch is changed from one position to another, and in which this desirable result is secured in a very simple manner by providing spring arms with the contacts themselves carried by the arms adjacent to the outer portion of the arms, and in which the inner portion of each of the arms is rigidly secured in place to thereby produce a wiping contact due to the flexing of the arms and consequently due to the shortening or shifting of the relative position of the several contacts.

This application is a continuation in part of our prior application filed December 29, 1958 for Electric Switches, Serial No. 783,398.

An embodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a view looking directly into the switch construction, such view showing the device with the cover or casing removed.

Figure 2 is a side elevation of the device shown in Figure 1.

Figure 3 is a sectional view on the line 3-3 of Figure 1.

Figures 4, 5, 6, and 7, are sectional views taken on the lines 44, 5--5, 6--6 and 7-7, of Figure 3, respectively.

Figure 8 is a view, broken away and partly in section, showing the switch inits position just after the first switching operation has been initiated.

Figure 9 is a view corresponding to Figure 8 showing the switch returned to its initial position.

Figure 10 is a wiring diagram showing one arrangement in which the switch may be used, such view showing the switch construction as applied to a refrigerator.

To simplify the description of the invention it is to be borne in mind that the switch construction is so arranged that a process, under the control of the switch, is time initiated and signal terminated. Stated in other words, the switch is designed to open a first circuit and close a second circuit at a predetermined selected time, and to close the said first circuit and open the said sec- 0nd Circuit in response to a signal given over a third circuit. 7

This sequence of operations is well exemplified where the switch is used to control the defrosting of a refrigerator, in which the defrosting operation is time initiated and temperature terminated, and in which a heater or hot gas means is provided for quickly raising the temperature, the switch then stopping the heater or the hot gas means, or any other defrosting means, and instantaneously starting the compressoror other refrigeratingmeans when the desired temperature has been reached. I

Referring toFigtrre l, the power supply contact or the reference characterlO'. What may be called the first contact blade is indicated at 11,and will be referred to a as the first blade or first contact or, in the case of a refrigerator, as the compressor contact or refrigerating means contact. Thes second contact blade or contact is indicated by the reference'chai'acter 12 and in the case of a refrigerator, is connected to a defrosting heater or 3 hot gas means and is referred to as the second blade or second contact or defrosting contact.

The schematic diagram, Figure 10, or wiring diagram for an electric refrigerator, showing one application of the invention, shows a compressor, indicated by the reference character 13, and a heater by the reference character 14.

The continuously running synchronous motor which drives the cam is indicated by the reference character 15.

The synchronous motor drives the pinion 16 which may hereinafter be referred to as the driving pinion or driving gear, see Figures 2 and 4, through reduction mechanism indicated generally by the reference character 17, see Figure 2.

The driving pinion 16 occupies a fixed position so far as any lateral motion is concerned, and drives the relatively large gear 18, see Figures 2, 5 and 6. The relatively large gear 18 meshes with the driving gear 16 under normal conditions, and forms a unitary structure with a pinion 19 and through the pinion 19 drives the gear 20. The gear 20 is rigid with-the twenty-four hour shaft or main shaft 21 which drives the driving finger 22 of lost motion mechanism, see Figures 1, 8 and 9, such lost motion mechanism being operatively positioned between the cam 23 and the driving pinion'16. The lost motion mechanism consists of the finger 22 and the notch portion 24 cut out of the cam 23 "and provided witha front or leading face 25 and a rear or trailing face 26. The driving finger 22 normally contacts the leading face 25 of the lost motion mechanism described immediately hereinabove, so that the cam 23 is drivenby the finger 22.

The'gear 18 and the pinion 19 are revolubly mounted on a pin 27, see Figures 2 and 5, and the pin 27 is rigid with a'swinging arm 28, see Figures 2, 4and 5, which arm is pivoted around the main or twenty-four hour shaft 21. This arm 28-is urged toward the driving pinion 16 by means of the spring 29 and the mechanism described hereinabove constitutes a Well known over-running clutch. V

The over-running clutch allows the resetting :of the timing finger 22 by means of the-knob or hand-wheel 30, so that the timing cam 23 can be set wherever desired, see Figure 2.

In reality, the'setting of the twenty-four hour shaft 21 sets the'position or determines the position of the driving finger 22 of the'lost motion-mechanism and through such lost motion mechanism, the setting of the cam 23.

Normally the three contact blades 10, 11 and Rare in the position shownin Figures 1-and 9, and the blades or contacts wand 11 are in engagement and the first circuit through the blades is closed, whereasthe second circuit through the blades, 10 and 12 is open.

It is to be noted that the timing cam 23-is provided with a shoulder 31 and with a notch 32. It is apparent that as the cam 23 is rotated in a clockwise direction as viewed in Figures 1, and 8, the driving finger 22 willbe in engagement with the front wall or face 25 of the lost motion mechanism, see Figures 1 and 8.

. When the timing cam 23 arrives at the position shown in Figure 8 it is apparent that thefirst blade 11 will drop past the shoulder 31 and'into the notch32, Whereasthe power blade or center blade 10 will be heldout of engagement with the blade or contact 11- of'the' first'circuit, and in engagement with the bladeor contact12 of the second circuit. In other words, the first circuitwill be open, and the second circuit closed.

It is to benoted that an insulating spacer 33 is provided and passes freely through the center blade-10 and is provided -with shoulders normally in engagement'with both blades 11 and 12, so that theseblades move in unison. All of the blades 10, 11"and 12 arebiased towards the right asshown" in Figure 8.

It is apparent from the description thus far given that the first circuit will be opened and the second circuit closed by the timing cam 23 as shown in Figure 8. In order to release the blade 10 and open the second circuit and reclose the first circuit, means are provided for advancing the cam 23 without'di'sturbing the driving finger or member 22. e 7

Means for advancing the cam23 and moving it from the position shown in Figure 8 to the position shown in Figure 9 constitutes an over-running clutch and is provided with an arm or pawl 34, see Figure 8, having a serrated or toothed bottom or inner end as indicated at 35. Normally this constitutes an over-running clutch. This over-running feature is accomplished due to the fact that the bottom or serrated portion 35 of the arm or pawl 34 is eccentric with reference to the pin 36 on which the arm 34 is pivoted so that as the timing cam 23 rotates in a clockwise direction it will freely ride or pass beneath the lower serrated face or portion 35 of the arm or pawl 34. The arm or pawl 34 is carried by an arm 37 pivoted about the main 24 hour shaft 21. The arm or pawl 34 is urged in a clockwise directionby means on one end of a spring 38, and tends to rock in a clockwise direction about the pin 36. The spring 38 bears at the other end against the face or portion 39 of an electromagnet 40, see Figure 1.

It is to be noted, however, that one arm of the spring 38 bears as stated against the projection 41 of the arm or pawl 34. It is to be noted also that an intermediate portion of the same arm of the spring 38 bears against a projection 42 formed on the arm 37, see Figures 1 and 2, which arm 37, it will be remembered, is pivoted so as to 'rock about the main or twenty-four hour shaft 21. Thus it will be'seen that the spring 38 also urges the arm 37 in a counterclockwise direction towards the electromagnet 40.

The electromagnet 40 is provided with an energizing winding 43. The rear or other magnetic pole of the electromagnet is indicated by the reference character 39. The electromagnet is provided with a plunger 44, which is urged towards the right as viewed in Figures 1, 8 and 9 when the winding 43 is energized, or in other words, when the electromagnet is energized. This plunger or armature 44 is arrangedto engage a finger 45 integral with the arm 37, and is thus arranged to rock the arm 37 in a clockwise direction as viewed in Figure 8, to the position shown in Figure 9. This clockwise direction of rotation of the arm 37 is transmitted through the pawl 34 to the timing cam 23, and moves'the timing cam from the position shown in Figure 810 the position shown in Figure 9, and thus allows or causes, the center or power blade 10 to engage the first blade or first circuit contact 11 and to disengage itself from the second contact blade or contact 12 for the second circuit, seeFigure 9.

The position of the arms or contacts 10, 11 and 12 when the contact or arm 11 has-dropped in the notch 32 is shown in Figure 8, and the position of the contacts or arms), 11 and 12 when the timing cam 23 has been advanced a slight amount by the electromagnet to the releasing position is shown in Figure 9.

It will be seen that the lost motion mechanism with its leading face 25 of the timing cam has been moved in a clockwise direction away from the driving finger 22 of the constantly driven main shaft or twenty-four hour shaft 21.

This to be noted from Figures 8 and 9 that the pawl 34 is provided with a projection 46 which limits the clockwise rotation of the pawl .34 in the event the pawl 34becomes free from engagement with the timing cam 23 and should rotate too far in a clockwise direction from anyjunforeseen cause whatsoever. i

7 It is to be noted'that the casing-47, see Figures 8 and 9, limits the retracted or lefthand motion of the plunger'44 of the -electrornagnet'40.' This casing is preferably of insulatingmateriah;

It will be seen that a novel timer has been provided in which no additional mechanism is required in the form of a tripping structure operated by a tripping or releasing mechanism. Instead, the cam means is moved directly from the tripping or releasing electromagnet plunger, thus greatly reducing the cost of construction and materially simplifying the construction and consequently reducing the time of manufacture and of assembly, and providing a device which is less liable to get out of order.

It will be seen further that the timer is very simple inv deed, and may be freely employed to control, for example,

the defrosting operation of an electric refrigerator, or to control any other operation desired. For example, it could control the sequence of operation or the duration of operation of electric signs and other devices.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

1. A timer switch comprising a cam, power means for driving said cam at a uniform rate, lost motion mechanism between said power means and said cam for allowing motion of said cam without moving said power means, means for simultaneously moving said power means and said cam for setting said timer switch, switch means comprising a first contact arm and a second contact arm, connecting means mechanically-connecting said arms together, and a main contact arm between said first and second contact arms and biased towards engagement with said first contact arm and normally held out of engagement with said second contact arm by said cam, said cam having a notch to allow said first contact arm to move away from said main contact arm while said cam holds said main contact arm in contact with said second contact arm, and means independent of said power means for advancing said cam to release said main contact arm and allow said main contact arm to move away from said second contact arm into engagement with said first contact arm, said arms being of spring material and having their contacting portions adjacent the outer ends and having the inner ends of said arms held in a rigid position, whereby the flexing of said arms produces a wiping action at their contacting portions.

2. A timer switch comprising a cam, power means for driving said cam at a uniform rate, switch means comprising a first contact arm and a second contact arm, connecting means mechanically connecting said arms together, and a main contact arm between said first and second contact arms and biased towards engagement with said first contact arm and normally held out of engagement with said second contact arm by said cam, said cam having a notch to allow said first contact arm to move away from said main contact arm while said cam holds said main contact arm in contact with said second contact arm, and means independent of said power means for advancing said cam to release said main contact arm and allow said main contact arm to move away from said second contact arm into engagement with said first contact arm, said power means including a revolubly driven finger and said cam having an aperture therethrough loosely receiving said finger and having a leading' edge with the finger normally in engagement with the leading edge of said aperture for driving said cam from said power means, whereby said cam can be advanced independently of said finger.

References Cited in the file of this patent UNITED STATES PATENTS 1,831,605 Porter Nov. 10, 1931 2,254,661 Markley et al Sept. 2, 1941 2,530,985 Morrison Nov. 21, 1950 2,536,256 Berg Jan. 2, 1951 2,553,846 Clemens May 22, 1951 2,675,442 VayRyan Apr. 13, 1954 2,690,526 Morrison Sept. 28, 1954 2,736,173 Duncan Feb. 28, 1956 2,847,525 Everard Aug. 12, 1958

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