US1334211A - Thermodynamically-controlled switch - Google Patents

Description

M. H. BAKER, DECD,

M. H. BAK R. ADMINISTRATRIX. THERMODYNAMICALLY CONTROLLED SWITCH. APPLICATION FILED SEPT. 17, I915. RENEWED IUNE 11, 1919.

Patented Mar. 16, 1920.

UNITED STATES PATENT curios MALCOLM I-I. BAKER, OF BRAIN TREE, MASSACHUSETTS; MARIE H. BAKER, ADMINISTRA- v TRIX OF SAID MALCOLM H. BAKER, DECEASED, ASSIGNOR TO KENNETH W. CROSBY,

TRUSTEE, or BOSTON, MASSACHUSETTS.

Specification of Letters Patent.

Patented Mar.16,1920.

-App1ication filed September 17, 1915, Serial No. 51,206. Renewed June 11, 1919. Serial No. 303,476.

To all whom it may concern:

Be it known that I, MALCOLM H. BAKER, a citizen of the United States, and a resident of Braintree, in the county of Norfolk and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Thermodynamically-Controlled Switches, of which the following is a specification.

My invention relates to electric switches involving in their operating mechanisms thermo-dynamic means for partial automatic control and has for its object, generally, to provide in such switches an arrangement of the thermo-dynamic controlling means whereby designed circuit-governing action of the switch may automatically be caused when such means. are thermally energized and particularly, but not exclusively, when such means are so energized by the electric current.

More specifically, the object is to thermodynamically control the relative movement of electrical contacts in such manner that said movement is permitted to occur a predetermined time after designed energization of the thermo-dynamic controlling 1neans,- or, in other words, to introduce a time element, comprising the operative period of a thermo-dynaniic device active to free the contacts for relative movement, between the act of energizing the said device and the actual making or breaking of the circuit.

As a preferred and specific embodiment of my invention, I have illustrated it herein as a time controlled, thermostatically governed. circuit breaking device,-and the particular form of such device that I have chosen for illustrative purposes is a oneway snap switch, of the single pole type, and of a common and well known mechanical arrangement. I

My invention may. however, be equally well applied to any other form of switch, such as a blade knife, push button, lamp socket, pendant. cord pull. or magnetically interval, varying from some ten seconds toa few minutes after manual extinguishment causing actuation of the switch and before material convenience, but often an actual safeguard against accidents.

That is, conditions of attainment being equally easy and reliable, a light which involved such continuation would practically always be chosen over one which did not.

My invention accomplishes this result not only in a simple and cheap manner, but in one which is absolutely reliable and durable, commercially.

In carrying out my invention, as specifically illustrated and described herein, I employ the usual snap switch,and I also employ a detent adapted to retain the switch contacts closed after the button has been turned to the off position, and other detent means to hold the button at said off position after it has been so turned. And I provide a thermo-dynamio device, adapted to be energized by the electric current, to free the said first detent means and permit the opening of the switch contacts after a predetermined time, the said thermo-dynalnic device being energized by the act of turning off the button.

For operatively energizing the thermodynamic device I may use any suitable electrical resistive unit, but I preferably employ a winding of resistance wire arranged in heating relation to said device.

' I have illustrated my invention in theannexed drawings, in which Figure 1 is a plan view, with the casing and control button removed and the parts shown in the circuit-broken position. Fig. 2 is a section taken on the parallel planes A--A of Fig. 1 with parts in same relation as therein shown and with the casing and control button appearing. Fig. 3 is a partial plan view, otherwise like Fig. 1 generally but with parts in the circuit-making position. Fig. 4 is a detail perspective view of the shaft and certain allied parts. Fig. 5 a partial section taken on the horizontal plane 13-13 of Fig. 2. the parts being shown in the intermediate position. or the one assumed after the button has been turned to its circuitbreaking position and while the thermostat is heating. Fig. 6 shows a detail of certain parts taken on the horizontal plane CC of '55 actual cessation of the light, is not only of Fig. 2, said'parts being positioned as in Figs. 1 and 3. Fig. 7 is a view similar to Fig. 3 but showing the intermediate position of parts above referred to. Fig. 8 shows the parts of Fig. 6 positioned correspondingly to Fig. 7 Fig. 9 is a detail view taken in section on the plane DD in Fig. 8. Fig. 10 is a diagram of electrical connections of the single-pole type of switch illustrated in the above figures; and Fig. 11 is a diagram of electrical connections suitable for a double-pole type of otherwise similar switch wherein the heat generating resistance unit is shown connected in shunt to the switch governed load when the control button is turned for causing delayed opening of the main contacts.

Throughout the several views of the drawings, identical parts are designated by the same reference numerals.

In the drawings, Fig. 1 to 9 inclusive, the button is shown at 1 and the shaft at 2, the latter being guided in bearings 3, at, mounted upon the porcelain base 5. The shaft also carries, fixed to it, a collar 6 having a notch 7 engaged by one end of a coiled spring 8 the other end of which is attached to a portion 30 of a plate 11 hereinafter described. This shaft also carries a cam 9 adapted to engage a radially sliding dog 10 guided in a recess plate 11 attached to and insulated from contact clips 12, 12. These clips are adapted to engage blades 13, H, mounted upon the base 5. At the lower end of the shaft 2, below the base 5, is attached a plate 15 arranged to engage, successively, and at diametrically opposite points, a spring pawl 16 mounted upon the base 5. This plate 15 carries, insulated from it, contact clips 17, 17, adapted to engage blades 18, 19, mounted upon the base 5.

A bi-metallic thermostat. arranged with the more expansible metal inside, is shown -at 20, and is mounted upon the base 5 by means of the bracket 21. This thermostat carries, at its opposite end from said bracket, a small plate 22 provided with a screw stud 23 engaging one end of a bell crankv 2 5 through a slot therein. This latter lever is pivoted at 26 to the bracket 21.

and has, at its other end, a stud 27 fitted with H a loose roller 28 adapted to engage, successively, the opposite extensions 29, 29, of the. recess plate 11. The thermostat is covered, with some suitable material such as asbestosv or mica, and is provided with a heating reslstance winding 33.

. l A ratchet 36 is fixed to the bracket 21 and arranged to engage a projection 34 of the sliding dog 10, as later set forth.

Operation is as follows, starting from the circuit-broken position of the switch as shown in Fig. 1,the button 1 is turned right handed in the usual manner, which rotatesthe shaft 2 and therewith the cam 9,

the latter causing the dog 10 to slide radially and outwardly until its projection 34 disengages the tooth 35 of the fixed ratchet 36.

At the same time the coil spring 8 is placed under tension and thereby snaps the clips 12, 12, into engagement with their blades 13, 14:, thus closing the main circuit. Just pre vious to this, however, the clips 17 17, have been moved into engagement with their blades 18, 19, thus shunting out the resistance 33.

While these operations have been taking The switch is now closed and operates as a' simple single pole switch.

Referring to the diagram of connections in Fig. 10, it is seen that current passes from line 37 through main contacts, here indicated at 38, then by way of wire 39 and auxiliary contacts, indicated at 10, around the resistance 33 and so to the load line 11, the resistance 33 being therefore practically dead.

When it is desired to open the switch, the button is rotated in the same direction until caught and held by the engagement of the plate 15 with the spring pawl 16. The main contacts are held closed by the engagement of the roller 28 with the projection 29 of the plate 11. Thus the coiled spring 8 is held under operative tension, ready to act to break the main contacts when the same are freed. At the same time the rotation of the shaft has opened the auxiliary contacts 1718, 1719, thus causing the entire line current to flow through the winding 33, which heats,bends the thermostat, and frees the roller 28 from the pro'ection 29, as shown in broken lines'in Fig. The stored energy of the coiled spring now snaps open the main contacts, thus breaking the circuit, both through load and resistance.

The intermediate relation of pa.rts,i. e..

therelation after the button has been turned to its circuit breaking position but before the main contacts are released to open,is'

shown in Fig. 7 and the relation after the said main contacts are opened of course appears in Fig. 1, save that in said figure the thermostat is shown as cooled.

The time element which shall elapse between the turning ofl of the button and the j rupture of the main circuit may readily be varied, with a given load, by altering the size or number of turns of the resistance 33,the size of the thermostat,-the engage- .with the resistance in shunt to the load volt age, the said switch being here preferably of the double pole'type, or, at least, of a type carrying both poles of the circuit as required for a shunt connection. I have not thought it needful to specifically illustrate this type as it merely involves the addition of a pair of contacts and a re-arrangement of the relative position of main and auXil-' be noted that the shunt circuit containing resistance 33 is tapped from the load side of the main contacts so that upon opening of the latter, said resistance is denergized.

It is evident that when the button 1 is rotated to the OH position, and while the thermostat is heating to free the switch contacts to separate, the controlling parts including said button are operatively locked against further movement. That is, the operator having once turned the button to the off position cannot turn same further, or to the on position, again until the switch contacts have opened. In this manner mistakes on the part of users of the switch are prevented, particularly in the case where no visible change is brought about by the movement on the button to the off position,- as when no indicator plate is used.

I find that the use of an indicator plate 32, placed above the collar 6 in the usual manner, is of advantage as showing the opment in other forms and arrangements of switch mechanisms than the specific example herein disclosed for illustrative purposes only. Without therefore limiting myself to the precise embodiments of my invention herein shown, what I claim is 1. In a two-branch -circuit controlling switch, in combination; master contacts arranged in series with the two-branch-circuit, a detent positioned normally to malntain said master contacts closed, thermo-dynamic means operatively related to said detent upon thermal energization to release said master contacts therefrom, a heating device.

in one branch of said two-branch-circuit for said thermo-dynamic means, control means adapted to put said .master contacts under tension for automatic opening, auxiliary contacts in the other branch of said two-branchcircuit, and manually controllable means for opening said auxiliary contacts simultaneously with the tensioning of said master contacts, whereby said heating device may be rendered operative thermally toenergize the said thermo-dynamic device.

In a two-branchcircuit controlling switch, in combination; master contacts arranged in series with the twd-branch-circuit, a detent positioned normally to maintain said master contacts closed, thermo-dynamic means operatively related to said detent upon thermal energization to release said master contacts therefrom, a heating device in one branch of said tWo-branch-circuit for said thermo-dynamic means, auxiliary contacts in the other branch of said two-branchcircuit, manually controllable means for establishing tension tending to open said master contacts and also for operating said auxiliary contacts, whereby said heating device may be rendered operative thermallyto energize the said thermo-dynamic device.

3. In a two branch circuit controlling switch, in combination; master contacts arranged in series with the two-branch-circuit, a detent positioned normally to maintain said master contacts closed, thermo-dynamic means operatively related to said detent upon thermal energization to release said master contacts therefrom, a heating device in one branch of said two-b-ranch-circuit for said thermo-dynamic means, auxiliary contacts in the other branch of said two-branchcircuit, and menu ally-actuated control means arranged upon one actuation to close both said master contacts and said auxiliary contacts, and further arranged upon subsequent actuation to open said auxiliary contacts and to tension said master contacts for the automatic opening thereof. a. A one-way, rotary snap switch embodying in combination; stationary contact members, a rotary contact device adapted conductively to bridge said members, manually operable means for controlling said device, a resilient connection between said device and said means, detent mechanism arranged cooperatively with said' resilient connection to produce a quick, tension-caused, followup movement of said devicerelative to'said means, a detent and controlling thermostat therefor positioned normally to retain said device in its contact-bridging position, a

latch arranged automatically to hold said means rotatively advanced and separated from said device against the tension in said resilient connection, and a heating circuit for said thermostat, with connections operative to energize said circuit when said means are so held rotatively seperated from said device.

5. A one-Way, rotary snap switch embodying in combination; stationary contact members, a rotary contact device adapted conductively to bridge said members, manually operable means for controlling said device, a resilient connection between said device and said means, detent mechanism arranged cooperatively with said resilient connection to produce a quick, tension-caused, follow-up movement of said device relative to said means, a detent and controlling thermostat therefor positioned normally to retain said device in its contact-bridging position, a latch arranged automatically to hold said means rotatively advanced and separated from said device against the tension in said resilient connection, and a heating circuit for said thermostat, with connections operatively to energize said circuit when said means are so held rotatively separated from said device, said connections being further arranged so that said circuit is automatically denergized by contact opening movement of said device.

6; A one-way, rotary snap switch embodying in combination; stationary contact members, a rotary contact device adapted conductively to bridge said members, manually operable means for controlling said device, a resilient connection between said device and said means, detent mechanism arranged cooperatively with said resilient connection to produce a quick, tension-caused, follow-up movement of said device relative to said means, a detent and controlling thermostat therefor positioned normally to retain said device in its contact-bridging position, a latch arranged automatically to hold said means rotatively advanced and separated from said device against the tension in said resilient connection, and a heating circuit for said thermostat, with connec tions automatically to establish said circuit solely in series with the switch governed load when said means are so held rotatively se arated from said device.

In an electric switch, in combination; manually controllable device for establishing the main switch contacts in normal closed relation and not tensioned for opensaid contacts for opening movement, an.

electrical resistance arranged in heating relation to the thermostat, and circuit connections governed by said device whereby contact-closing movement of said device establishes a two-path series-parallel connection through the switch, one path thereof containing said resistance and the other path thereof forming a shunt circuit around said resistance; together with means arranged automatically to open said shunt circuit simultaneously with the tensioning of said contacts.

8. A snap switch embodying in combination; a rotary contact de ice, manually con-- trollable means for rotating said device, an auxiliary contact device operably related to said means, a resilient connection between said means and said rotary device, detent mechanism adapted automatically to cause a quick, follow-up movement of said rotary device relative to said means, a latch arranged to arrest said means in a position tensioning said rotary device for circuit breaking movement, a detent and controlling thermostat therefor positioned normally to prevent circuit breaking movement of said rotary device, and a. heating circuit for the thermostat, adapted to be energized by movement of said means to its said tensioning position.

9. In a one-way snap switch, in combination with a circuit-gove1'ning, spring-actuated rotary contact device, and a thermostat arranged automatically to control the movement thereof, a radially projecting member carried by the said device and a pivoted detent lever having one end thereof adapted to engage with said projection for preventing movement of said device, and having the said thermostat operatively connected to another portion thereof, the said detent lever being pivoted substantially upon a line tangential to the arc of movement of said projecting member.

10. In an electric circuit switch, manually controlledmeans adapted at one actuation thereof to close the switch and at the next actuation thereof to energize mechanism tending to open the switch, means to retain the said switch closed, means to lock the said controlling means against reverse movement aftersaid second actuation thereof; together with a thermostat to govern the said retaining means, and a heating circuit for the said thermostat, the said heating circuit being energized by the said second actuation of the manual controlling means.

11. In a thermostatically governed electric switch, in combination with the contact members having relative movement to open and to close the switch, and a thermostatic detent to restrain said opening movement, controlling means to close the switch and to IIO cause opening of the switch, and means to lock said controlling means in inoperative relation to the switch contacts after said means have been moved to a position adapted to cause opening of the switch and until said switch is opened.

12. In a single pole electric switch, in combination; master contact members and a detent normally positioned coiiperatively therewith to prevent circuit breaking move ment of said members, a thermo-dynamic device arranged coiiperatively with resilient means when energizedautomatically to open said contacts; a two-path, divided circuit in series with said master contacts including in one branch thereof said device, auxiliary contacts arranged in the other branch of said divided circuit, and common manual controlling means for both said master and said auxiliary contacts.

13. In a single pole, electric switch, in combination; movable contact members and a detent normally positioned cooperatively therewith to prevent circuit breaking movement of said members, a thermo-dynamic de vice arranged cooperatively with resilient means when energized automatically to separate said members, a circuit governed by said contact members, including in one'branch thereof said device, auxiliary contacts for short-circuiting said device, and manual controlling mea-ns arranged to close both said members and said auxiliary contacts, and upon subsequent actuation thereof to establish tension tending to separate said members and simultaneously to open said auxiliary contacts.

14. In a single pole, electric switch, in combination; master contact members and a detent normally positioned cooperatively therewith to prevent circuit breaking movement of said members, a thermodynamic device arranged cotiperatively with resilient means when energized automatically to open said contacts; a two-path divided circuit in series with said master contacts including in one branch thereof said device, auxiliary contacts arranged in the other branch of said divided circuit, and manual controlling means arranged simultaneously to close both said master and said auxiliary contacts and upon subsequent actuation thereof to open said auxiliary contacts and simultaneously to establish tension tending to open said master contacts 15. In a rotary snap switch including an insulating base, stationary contact terminals mounted thereon and a rotatable contact device carrying a contact plate insulated therefrom and adapted in alternate sta es of rotative progression conductively to ridge said terminals, in combination; a concentrically pivoted shaft having resilient and detent connection with said device for ing position, a spring detent mounted beneath the insulating base and adapted to hold said shaft relatively advanced and separated under tension from said device when the latter is so intercepted, a thermostat and heating circuit therefor arranged when energized to actuate said lever and release said device, and'an auxiliary current switch positioned beneath the insulating base and adapted to be operated by movement of said shaft, whereby said heating circuit may be electrically energized when said device is tensioned for circuit breaking movement.

16. In an electric switch embodying a 1'0- table, contact-bridging structure for controlling the main circuit, said structure being arranged to engage conductively with stationary circuit terminals in alternate stages of progressive rotation, and embodying also an actuating device for said structure, having tensioned connection thereto and stop means positively preventing reverse movement of said structure and of said device between said stages, in combination; a movable detent normally arranged and positioned to intercept circuit-breaking movement of the said contact-bridging structure; a pawl detent operatively associated with the said actuating device thereby to hold the latter in position tensioning said structure for movement into a circuit breaking position; a thermostat normally positioned and formed cotiperatively with said movable detent to prevent the release of said structure from said movable detent; a normally inactive electric heating unit for the thermostat; and auxiliary switch means operably related to the said actuating device and elec trically connected, when said device occupies its said tensioning position, to divert current through said electric heating unit, thereby to energize operably the thermostat for causing a delayed release of said structure from said movable detent.

17. In an electric switch embodying a rotatable, contact-bridging structure for controlling the main current; said structure be ing arranged to engage conductively with stationary circuit terminals in alternate stages of progressive rotation, and. embodying also an actuating device for said structure having tensioned connection there to and stop means positively preventing reverse movement of said structure and of said device between said stages, in combination; a movable detent normally arranged and positioned to intercept circuit breaking movement of the said contact-bridging structure; a pawl detent operatively associated with the said actuating device thereby to hold the latter in position tensioning said structure for movement into a circuit breaking position; a thermostat normally positioned and formed coiiperatively with said movable detent to prevent the release of said structure from said movable detent,

a normally, inactive electric heating unit for the thermostat; and an auxiliary contact bridging structure fixedly carried by said actuating device, and positioned thereon, when said device occupies its said tensioning position, to divert current through said electric heating unit, thereby to energize operably the thermostat for causing a delayed release of said structure from said movable detent.

18. In a current supplied electric circuit, the combination of a load, a cut-out, and a divided circuit all in series, said divided circuit containing in one branch thereof, a current governed device operatively related to said cut-out, and said divided circuit containing in another branch thereof a current switching means for governing the supply of current to said device.

19. An electric switch embodying a progressively rotatable contact member; an actuator. element mounted for progressive step-by-step rotative movement relatively in advance of said members; a spring and de tent connection between said member and said element whereby rotative advances of said element relative to said member cause quick, follow-up rotative movements of said member, respectively to make and to break a circuit; a separate detent arranged to prevent said follow-up movement of said memher from its circuit-making position when said element is rotatively advanced; means to hold said element so rotatively advanced, whereby said member is tensioned for cir- 'cuit-breaking movement; and normally inactive, slow-acting, instrumentalities arranged to be operatively energized by the said rotative advance of-said element, and thereby rendered operative to tree sald con-' tact from said separate detent after a predetermined interval of time.

Signed at Braintree, in the county of Norfolk and Commonwealth of Massachusetts, this 16th day of September, 1915.

MALCOLM H. BAKER.

Witnesses SELoRI AMoRoso, RAYMOND D. SMITH.

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