US2350978A - Combined safety switch and limit control - Google Patents

Description

June 13, @9449 e 2/ I & J7 w 4% H. F, ALFERY COMBINED SAFETY SWITCH AND LIMIT CONTROL Filed June 19, 1941 2 Sheets-Sheet l 62 jrzzxenib r:

fienr ymg er g June 13, 1944; ALFERY I 2,350,978

COMBINED SAFETY SWITCH AND LIMIT CONTROL FilecLJune 19, 1941 ZSheets-Sheet 2 trol for opening the circuit "other different abnormal Patented June 13, 1944 2,350,918 COMBINED SAFETY SWITCH AND LIMIT CONTROL Henry F. Alfery, Milwaukee, Wis, assignor to Milwaukee Gas Specialty Company, Milwaukee, Wis, a corporation of Wisconsin Application June 19, 1941, Serial No. 398,756

. 8 Claima This invention relates, generally, to protective devices for burner apparatus, and it has partic-:

ular relation to limit control While the particular device which I shall describe in connection with the drawings is a coma combined safety switch and bined safety switch and limit control operative to cause a valve in the fuel supply pipe leading to the burner to close not only whenever a flame to which the device is responsive-as a pilot flame-goes out, but also upon the occurrence of an abnormal temperature, it is to be understood that the invention, in its broader aspects,

is not limited to this particular use but may be employed in all similar work as suitable or desired.

Moreover, while I have shown and shall describe the combined safety switch and limit control of the present invention in connection with a valve that requires current only for opening the same, the invention is not limitedto use with valves of this particular type, but may be employed with valves that require current for both opening and closing the valve, and it is to be understood that the combined safety switch and limit control may be used for controlling other circuits and other devices than the particular circuit and particular device selected for illustration.

One of the main objects of the invention is to provide a combined safety switch and limit coninto which the device is connected, for example, not only upon extinguishment of the flame to which the device is responsive, or upon the occurrence of some While the particular structural features and combinations by which I obtain a device of the character set forth are-important features within the more specific aspects of the invention, it is to be understood that the precise features shown and described may b varied within the broader aspects of the invention.

In order to acquaint those skilled in the art with the construction and operation of a safety switch embodying the present invention, I will now describe, in connection with the accompanying drawings, one preferred embodiment of the invention.

In the drawings:

Figure 1 is a front view of a combined safety switch and limit control embodying the present invention, partially in section and with the cover removed, and showing the switch in closed position; a

Figure 2 is a side elevational viewof the combined safety switch and limit control;

other abnormal condition or malfunctioning of the apparatus, but'also upon the occurrence of an excessive temperature or other additional abnormal condition or malfunctioning of the apparatus. 1

Another object of the present invention is to provide, in a device of the character set forth, a switch or other control device which is adapted to be reset to closed or when the flame to which the device is responsive is burning and when the temperature has dropped below the excessive temperature. at which the limit control is operative, or when the conditions device is responsive are cured.

Another object of the invention is to provide a combined safety switch and limit control which is of simple, inexpensive, and improved con struction em odying few parts and operative cf.

fectively to accomplish the results set forth.

to which the operating position only Figure 3 is a more or less diagrammatic view showing the switch in front elevation and in connection with burner apparatus;

Figure 4 is a fragmentary detail view showing the position of the switch actuator and reset means, with the reset member pressed inwardly to cock or reset the device;

Figure 5 is a view similar to Figure 4 showing the position of the switch actuator and resetmeans with the switch in open position and the reset member and reset stem released; and

Figure 6 is a detail section taken on the line 8-8 of Figure 4.

In Figure 3 of the drawings, a gas or other fuel burner of any suitable or preferred type is conventionally illustrated at II. The burner in may be the burner of water'heater, floor furnace, gas range, or any other burner. A gasor other fuel supply pipe Ii leads to the burner III for the delivery of gas or other fuel theretofor example, through a mixing chamber (not shown) to which air is admitted in the usual way, as well understood in the art.

A power actuated or electroresponsive valve 9. room or space heater,

the actuator member.

l8 leading'to any suitable source of current or power (not shown). The valve actuating means for the valve i2 is connected into the secondary circuit I9. The safety switch and limit control of the present invention is also connected into the secondary circuit l9, as will presently appear. For purposes of illustration, it may be as-- E sumed that the valve 12 is of a character to be actuated to open position by closing of the circuit l9, and to beheld in open position to supply fuel or operative energy to the burner It) as long as the circuit is is closed. The valve l2 may have spring means, or other suitable means, for actuating the valve to closed position to shut oil the supply of fuel to the burner in when the circuit is is opened or otherwise disabled.

The safety switch selected for illustration is similar to that more fully disclosed in the copending application of Harold A. Montz, Serial No. 394,601, filed May 22, 1941, which became Patent No. 2,340,197 on January 25, 1944, but it is to be understood that the construction and operation of the safety switch part of the com-'- bined safety switch and limit control of the present invention may, within the broader aspects of the invention, be of any other suitable orpreferred form.

The safety switch and limit control is shown as located within a housing 20. The opposite ends of the back wall of the housing are turned in to form end-walls 2|, and, at the opposite slot 45 through which extends a pin 46, the opposite ends of which are secured in the opposite sides of the forked inner end of the actuator sides of the back wall, are inturned flanges 22.

The cover 23, which may be of generally U-' shaped cross section, fits over the inturned end walls 2|, with'the inner marginal edges of the sides of the cover fitting over the flanges 22. Slots 24 opening inwardly from the inner marginal edges of the side walls of the cover fit over the shanks of screws 25 having threaded engagement in the side flanges 22. These screws 25 are adapted to be tightenedto secure the cover in place on the base of the housing, and to be loosened to permit removal of the cover. The

screws 25 and slots24 may be positioned at different distances from the opposite ends of the device to assure proper moimting of the.

cover 23.

The front wall of the cover 23 has an opening member 30.

The cam lever 42 has secured thereto, for example, at 48, an overtravel spring arm 49 for actuating the switch to closed position. The lever 42 carries a flag or indicator member 50. This indicator member 50 has on and oil markings thereon as shown, or is provided with colored or other appropriately marked portions for indicating through the opening 26 in the switch cover 23 the position of the switch, as will presently appear.

The means for holding the reset member in the position shown in Figure 1 so that the switch will close when the actuator member is released following its inward resetting movement and will remain closed as long as the member 40 is held in the position shown in Figure 1 :and the actuator member 30 is in its outwardly projected position is shown in the form of an electromagnet located within the housing 20. The electromagnet'selected for illustration comprises a magnet frame 56 -secured, for example, to aterminal bushing 51 in the manner more 1 fully disclosed in the copending application of 26, shown in'Flgure 3 and in dotted lines in Figures 1, 4, and 5. through which opening .an indicator is adapted to be viewed to indicate the position of the switch, as will hereinafter appear.

An actuator or reset member 30 operates between open and closed positions by rectilinear movement through an opening 3| in the adjacent end wall 2! of the housing. The outer end of the actuator member 30 is provided with an operating button 32. The actuator member 30 is shown as comprising a pair of actuator member parts forming a fork at the inner end of the actuator member and secured together outwardly of the forked inner end. A pin 34, secured in the actuator member 30 outwardly of its forked inner end, cooperates with" the adjacent end wall 2! to limit outward movement of The actuator member 30 is yieldingly retained in its outwardly projected position as shown in Figures 1 and 5, and upon release of thebutton' 32, as will presently appear, is returned to this outwardly projected position by a coiled return spring 36. This spring 36 is shown .as connected between the innerend of the actuator member 34 at 31 and a spring anchoring-lug 38 pressed Clarence Wantz, Serial No. 328,923, filed April 10, 1940. The coil 58 of the electromagnet is wound around the legs of the magnet frame 56. The bushing 51 is shown as extending through an opening 59 in the adjacent end wall 2|, and as externally threaded for threaded engagement at 60 with a nut 62 by means of which the bushing is clamped in place in the end wall 2| of the switch housing.

The electromagnet has an armature 64 attached at 65 to the adjacent end or a stem 66, if desired, in a manner to permit self-accommodation of the armature when in attracted posi-' tionto the pole ends of the magnet frame 56.

The electromagnet and armature are enclosed within acup 68. The stem extends for reciprocatory movement through an opening 69 in the inner end of the cup 88. The opening 69 is sealed by suitable sealing material, such as a leather washer, felt packing or the like, as in- .dicated at 10, interposed between the inner end of the cup 68 and a spring seating disc 12. The

.end of the stem 68 opposite the end on which the armature 64 is mounted is secured, for example, bya pin 13- to the adjacent end of the reset member 40. A coiled spring 14 interposed between the spring seating disc 12 and a spring seat member I5 actuates the armature 64 to retracted position and the reset stem and reset -member 40 to the position shown in Figure 5 ass cra the device. 'Ihe'tontact pins II are connected to terminals II. The conductors ll, of the circuit for the valve l2, which conductors are insulated at 4, enter the housing '2. through an insulating grommet ll. One of the conductors I9 is connected to the terminal '2 for one switch pin 80, and the other conductor I! is connected to the other terminal .2 for the other switch Pin 80.

The switch stem 8| has rectilinear sliding movement in the insulating base or block oi the switch 18 with the outer end of the stem in position for cooperation with the free end of the switch operating spring arm 4. on the cam lever 42. Within the switch block, the reduced inner end of the stem ll passes through a bridging contact plate II. A coiled spring 92, surrounding the reduced-innerend of the stem 88 and interposed between the contact plate 0. and an abutment 9! on, or forming a part oi, the switch base, yieldingly urges the plate 9| out of bridging contact with the contacts OI to open the circuit I. By engagement of the contact plate 20 with the shoulder 94 on the stem ll, the spring 92 also yieldingly urges the stem II to its outwardly projected position as shown in Figure 5. .Stop'means (not shown) may be provided ior limiting the outward movement of the switch pin ll under the action of the spring 22.

The pilot burner 25, which is located in juxtaposition to the main burner ID to maintain a pilot light for lighting the main burner, is supplied with gaseous iuel by a pilot supply pipe 86. The pilot supply pipe 28 may be connected with the main fuel supply pipe ll anterior of the valve l2, or it may be supplied with fuel for delivery to the pilot burner in any other desired manner.

Athermocoupie, indicated at 98, is placed in position so that the hot junction 85 thereof will be heated by the pilot flame as long as the pilot flame is burning. The construction of the thermocouple may be similar to that more fully disclosed in Oscar J. Leins Patent No. 2,126,564, granted August 9, 1938, or a thermopile, or any other form of thermoelectric generator may be employed.

For the purposes of the present description, suffice it to state that the particular thermocouple 98 shown in the drawings comprises an outer tubular therrnocouple member and an inner metallic thermocouple member of different thermoelectric characteristics. The inner thermocouple member is joined at one end to the outer end of the outer thermocouple member to form the thermoiunction 89 which is placed in position to be heated by the pilot flame. An inner lead conductor I0 is joined to the inner thermocouple element to form an internal thermojunction, and an outer tubular lead conductor I03 is connected to the outer thermocouple member-for instance, through a sleeve to form a third thermoiunction. The lead conductors are of flexible character so as to be readily bent to insure neat installations. The inner lead conductor Hill is insulated from the outer'lead conductor i03, for instance, by-a wrapping of insulation I04 on the inner lead conductor.

A quick detachable or removable connection is preferably provided between .the coil 58 of the electromagnet and the ends of the leads I" and I 03 opposite the ends which are connected to the thermocouple. This removablelead conneo-' tion may be of the formdisclosed in the copending application of Clarencewantz hereinbefore identified,}and is illustrated in that form,

- actuator member ll although it may be of any other suitable or preferred form. Suillce it to state that the inner lead I" has a connector cone III which seats in the correspondingly recessed outer end oi the terminal tip I II and is clamped in contact therewith by a connector sleeve Ill. The adjacent end of the outer tubular lead conductor I" is connected in circuit with one side 0! the coil us through the bushing I1, and the other side oi the coil is connected to the terminal tip I", the parts being suitably insulated as shown.

To start the operation of the system shown in the drawings, as thus far described, the following sequence is followed:

The actuator or reset member 30 is'pressed inwardly'irom the position shown in Figure 5 by engaging the button 32 with the hand or fingers and imparting pressure thereto. The armature I4 is in released or retracted position at the beginning of the inward movement of the actuator member 3., and the spring 14 holds the pin 43 in engagement with the'lnner ends of the slots 44. As a result, the inward movement of the moves the reset stem 66 with it in the'same direction until the armature 64 is cooked or set into attracted position against the pole ends of the magnet frame It.

The pilot burner 05 is lighted, or, having been lighted, heats the thermoelectric generator, and

the actuator member 20 is held pressed inwardly until the heat of the pilot flame on the thermoelectric generator has energized the electromagnet sufllcently so that it will hold the armature 64 attracted thereto.

When the electromagnet is energized suillcient- 1y to hold the armature 64 in attracted position, the actuator member 30 is released and the reset stem 66 and reset member 40 remain in cocked position holding the pivot 48 for the cam lever 42 in the position shown in Figure 4. The switch operating spring arm 49 assumes the position shown in Figure 4 when the actuator member 30 is pressed inwardly. Then with the armature held attracted to the magnet frame 58, thereby holding the pivot 48 for the cam lever 42 in the position shown in Figur 4, when the actuator member 30 is released the outward movement of the actuator member a, under the action 01' the spring It, causes the pin 46, by its outward movement in the cam slot 45, to swing the arm 49 in a counterclockwise direction (Figures 1 and 4) about the pivot 43 from the positionshown in Figure 4 to'the position shown in Figure 1. The arm 48, by cooperation with the outer end of the switch pin ll in this movement, moves the contact plate 9| inwardly against the action of thespring 92 and into bridging contact with the conv character of'thespring arm 4! assures good firm eontact'of the-contact plate 92 with the contacts ll, there being preferably some overtravel of the cam lever 42 after engagement of the contact plate II with the contacts II which tensions the spring arm 49 to assume firm and tensioned contact.

If the pilot burner is not lighted to produce the thermoelectric current for holding the armature 44 in attracted position upon setting the same to that position by the actuator member the spring I4 then operates to move the armature 64 to retracted position. The cam lever 42 moves outwardly with the movement of the reset stem 66 to released position through the pin connected at 43,and the 'cam slot 45, cooperating with the pin 46 by this movement of the cam lever 42 relative to the actuator member 30, swings the arm 49 in a clockwise direction about the pivot 43 t the position shown in Figure 5. This releases theswitch pin 88, and the spring 92 separates the contact plate 90 from the contacts 60. This opens or interrupts the circuit l9, and the valve I2 operates to closed position to shut off the supply of fuel to the main burner.

When the armature is in retracted position with the actuator member 30 in released position as shown in Figure 5, the off marking on the indicator arm 50 is positioned to be viewed through the opening 26 in the cover of the housing to indicate that the switch is off. When the armature is in attracted position and the releasing the switch pin 86 so that the switch opens under the action of the spring 92.

When the temperature to which the limit control is responsive drops below the temperature for which the limit control is set, the tripping lever I35 is turned in a clockwise'direction (Figure 1) to position to permit resetting the deactuator member 30 is in its outwardly projected I surrounds a shaft I26 journaled for turning movement, for example, in the back wall of the housing 20. One end of the bimetallic element I25 is secured at I28 to the outer end of the shaft I25. The other end of the bimetallic element is secured to an adjusting lever I30 which is mounted to be turned about the axis of the shaft I26 and relative to the shaft. The

adjusting lever I30 has a pointer I32 which cooperates with the temperature markings on the dial I34.

The end of the shaft I26 opposite the end which is secured to the bimetallic element I25 extends into the hcusing-26 and carries, for tuming movement therewith, a tripping lever- I35. The cam lever 42 has a laterally extending lug I36 which carries a tripping pin I38 having a roller I39 for cooperation with the tripping lever I35. a When the selected temperature is reached as determined by the setting of the pointer I32 along the temperature markings on the dial I34, the bimetallic element I25 turns the shaft I26 and thereby the arm I in a counterclockwise direction from the position shown, for example, in Figure 1. Assuming that the armature I34 is in attracted position, with the actuator member 30 in released position and the switch closed as shown in Figure 1, this counterclockwise movement of the tripping lever I35 causes-this lever to engage the roller on the tripping pin I38 and to lift the cam lever 42 upwardly as the device is viewed in Figure. 1. This separates the armature 64 from the magnet frame 56. As

a result, the reset stem moves to retracted posi-- tion and the' arm 49 moves to released position vice in the manner already described. As long as the limiting-temperatureor other limitingcondition to which the limit control is responsive continues, however, the tripping lever I35 is positioned to prevent resetting the device.

The embodiment of the invention shown in the drawings is for illustrative purposes only and it is to be expressly understood that said drawings and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

I claim: I

1. In a device of the class described, in combination, a reset stem, an actuator member, a cam lever pivoted to said reset-stem, cam means on said actuator member for cooperation with said lever, said actuator member cooperating with said reset stem independently of said cam lever for resetting said stem to reset position, means for holding said reset stem-in reset position, a controlling member actuated to-operating position by swinging movement imparted to said cam lever by cooperation of the cam means on the actuator member therewith upon movement of said actuator member to released position with said reset stem held in -reset position, movement of said reset stemto retracted position upon release of said holding means swinging said cam lever in a counterdirection by cooperation between said cam lever and the cam means on said actuator member for movement of said controlling member to safety position, and limit control means cooperable with said cam lever and operable to separate said reset stem from said holding means for movement of said controlling member to safety position.

2. In a switch of the class described, in combination, a reset stem, an actuator member, a

cam lever pivotedto said reset stem, cam means on said actuator member for. cooperation with said lever, said actuator member cooperating with said reset stem independently of said cam lever for resetting said stem to reset position, meansfor holding said reset stem in reset position, a switch pin having on" and ofi positions and spring-pressed to one of said positions, a spring arm carried by'said cam lever and cooperating with said switch pin to actuate said pin to its other position by cooperation of the cam means on the actuator member with said cam lever upon movement of the actuator member to released position with said reset stem held in reset position, and limit control means cooper-- able with one of the parts comprising said reset stem, said actuator member, and said cam lever, and operative to separate said reset stem from said holding means for movement ofthe switch pin to the position opposite the position to said pin is spring-pressed. 3. In a switch of the class described, in combi nation, a reset member movable between reseet which and released positions by rectilinear movement,

her in reset position. a cam lever pivotedto said- 2,850,978 reset member and having a cam slot therein, a

cam pin carried by said actuator member and engageable in said cam slot for swinging said cam lever in one direction about its pivotal connection with said reset member upon movement of the actuator member to released position with said reset member held in reset position and swinging said cam lever in a counter direction upon movement of said reset member to released position, a switch operating member movable between on and "oil" positions, a spring arm carried by said cam lever and cooperating with said switch operating member to actuate said member to one of its positions by swinging movement imparted to said cam lever b movement of said actuator member to released position with said reset member held in reset position and actuated to its other position by movement of said reset member to released position, and limit control means cooperable with said cam lever and operative to separate said reset member from said holding means for movement of said switch member to the position to which it is actuated upon movement oi the reset member to released position.

4. In a switch of the class described, in combination, a reset member movable between .reset and released positions by rectilinear movement,

inits second position, movement of said reset member to its first position when said actuator member is in its first position causing movement or said control member to its said first position, an electromagnet for releasably holding said re set member in its said second position, and limit control means cooperating with said lever for urging said reset member away from said elec-' first position to its second position and movement of said actuator member from its second position to its first position moves said control member from its first position to its second position when an actuator member movable between resetting and released positions by rectilinear movement and adapted for resetting said reset member to reset position, means for holding said reset member in reset position, a cam lever pivoted to said reset member and having a cam slot therein, a

cam pin carried by said actuator member and engageable in said cam slot for swinging said cam lever in one direction about its pivotal connection with said reset member upon movement or the actuator member to released position with said reset member held in reset position and swinging said cam lever in ,a counterdirection upon movement of said reset member to released position, a switch operating member movable between "on and off': positions, a spring arm carried by said cam lever and cooperating with said switch operating member to actuate said member to one oij its positions by swinging movement imparted to said cam lever by movement 01' said actuator member to released position with said reset member held in reset position and actuated to. its other positionby movement of said reset member to released position, and limit control means cooperable with said camlever and operative separate said reset member from said holding means for movement or said switch member to the position to which it is actuated upon movement of the reset member to released position.

5. In a combined saiety switch and limit controLaswitchconn-oImemberhavingafirstpoaiflon and a second position, an operating lever for said member, raetting means cooperating with said lever comprising an actuator member yieldingly held in a first position and movable therei'romtoasecondpositionandaresetmembermovablei'romafirstpositiontoa'seeondposition and vice versa and yieldingly urged towarditssaidfirstpoeitimmeanawherebymovementoisaidactuatormemberiromitsfirstposition to its second position moves said reset memberfromitsfirstpositicntoitssecondposition and movement oi said actuator member iromitssecondpoeitiontoitsfirstpoeitionmoves stldcmtrolmemberfromitsflrstpoaitimtoits said reset member is held in its second position, movement of said reset memberfrom its said second position to its said first position causing movement of said control member to its first position, said reset member being yieldingly urged toward its said first position, an electromagnet which when energized holds said reset member second position when said-reset member is held u in its said second positioh, and limit control means cooperating with said resetting means for mechanically urging said reset member away from said electromagnet witha i'orce effective for releasing said reset member from said electromagnet.

'7. In a combined safety switch and limit control, a switch control member having a'first position and a second position, resetting means comprising a reset member having a reset position and 9. released position and an actuator member movable from afirst position to a second position 101' resetting said reset member, means whereby said control member is moved into its first position in the movement of said actuator memberto its second position and in the movement of said reset member to its released position when said actuator member is in its first position and is also moved to its second position in sition, and limit control means for mechanically urging said reset member away from said electromagnet with a force eil'ective for releasing said reset member therefrom.

8. In a combined safety switch and safety control, a switch control member having a first position and a second position, actuating means for movin said control member from its said first position to its said second'position, an electromagnet which when energized holds at least a portion of said actuating means in position for seeming and maintaining said switch control 4 member in its said second position. and limit control means operative to impart a force to the held portionorsaidactuatingmeansinadirection away from said electromagnet efiective to releaserromthelattersaidheldportionotsaid actuating means.

HENRY l". ALIIRY.

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