US2375387A - Circuit controlling device - Google Patents

Description

y 3, 1945. c. F. ROBBINS 2,375,387

CIRCUIT CONTROLLING DEVICE Filed Oct. 31, 1941 5 Sheets-Sheet l II ll 2, Z

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CIRCUIT CONTROLLING DEVICE Filed Oct. 31, 1941 5 Sheets-Sheet 2 Fnirimlllllll y 1945. c. F. FQOBBINQ CIRCUIT CONTROLLING DEVICE 3 Shets-Sheet 3 Filed Oct. 31 1941 Patented May 8, 1945 CIRCUIT CONTROLLING DEVICE Clyde F.-Robbins, Milwaukee, Wis assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corn tation of Delaware Application October 31, 1941, Serial No. armor (cl. zoo-31.5)

13 Claims.

This invention relates to circuit controlling devices, and more particularly to automatic temperature control switches for use in connection with electric refrigerators.

The invention has among its objects to simplify the construction, increase the life and improve the operating characteristics of switches of the aforementioned type.

Another object is to provide a refrigerator control switch which is of relatively small size'and is built up largely of stamped and formed sheet metal parts which can be readily manufactured and assembled at low cost.

Another object is to provide a refrigerator control switch having an improved snap operating mechanism which is simple in construction and exceedingly positive and reliable in operation.

Another object is to provide a control switch for electric refrigerators having an improved manual adjusting mechanism for regulating the temperature which is maintained within the refrigerator cabinet, and for also rendering the refrigerator inoperative for defrosting.

Another object is to provide a refrigerator control switch in which the switch contacts and their associated terminal members constitute a unit which is detachably secured to an assembly inscope of the appended claims.

In the drawings,

Figure 1 is a top elevational view of a control switch embodying the invention, a, cover and a front plate for the switch being shown in section;

Fig. 2 is a sectional view taken on line 2-4 of Fig. 1;

Fig. 3 is a sectional view taken on line 3-3 of Fig- 2;

Fig. 4 is a sectional view on line 4-4 of Fig. 1 illustrating the switch operating mechanism ll circuit closing position;

Fig. 5 is a fragmentary sectional view alsc taken on line 4-4 of Fig. 1 illustrating the switch operatin mechanism in circuit opening position;

Fig. 6 is a sectional view on line 6-6 of Fig. 1;

Fig. 7 is an exploded perspective view of certain of the parts shown in Figs. 1 and 2, and

Figs. 8 and 9 are diagrammatic views illustrat- 4 in circuit closing and circuit opening positions.

The refrigerator control device illustrated'in the drawings includes a switch unit I and a unitary operating assembly therefor including a snap operating mechanism 2 and a pressure responsive device 3. The snap operating mechanism 2 and pressure responsive device 3 are mounted upon a. rectangular base plate 4 having a U- shaped cover 5 mounted thereon, and said pressure responsive device has a loading spring 6 associated therewith which is adjustable by a knob l. I

More specifically switch unit I as shown in Figs. 3 and 4 is provided with a molded insulating base 8 which carries a pair of stationary contacts 8-9 and a cooperating bridging contact l0. Insulating base 8 is secured to a downwardly extending projection H on the rear end of base plate 4 by a screw I! (Fig. 2) and said insulating base is shaped to fit within the rear end of cover 5. Stationary contacts 9 and bridging contact I 0 are located within a recess formed in the front face of insulating base 8 and said stationary contacts are carried by a pair of terminal members II which are held in position upon said base by rivets I4. The rear face of insulating base I is provided with a circular recess I5 for receiving a conventional attachment plug and the terminal members I3 are provided with prongs it which extend rearwardly through openings in said base into said recess for engagement with the contacts associated with the attachment plug. As shown in Fig. 3, bridging contact I0 is biased to engage its associated stationary contacts 9 by a spring H which is held under compression between said bridging contact and an insulating cover plate l8 secured to the front end of base ill by a screw I9 shown in Fig. 2. Bridging contact, I0 is movable out of engagement with its associated stationary contacts 9 against the action of spring H by a pair of insulating bell crank levers v2i! which are located adjacent the opposite ends of said bridging contact as shown in Fig. 3. As shown in Fig. 4, each of the bell crank levers 20 is fulcrumed upon a ledge 2| formed on the front face of insulating base 8 and each has an upstanding arm 22 which is located to the rear of bridging contact l0 and a forwardly extending arm 23.

The snap operating mechanism 2 for switch unit i is mounted upon a pair of upstanding projections 24 formed on the opposite sides of an opening 24' in base plate 4, and said mechanism comprises an operating lever 25, a control lever 26 and apair or over-center springs 21. As shown in Fig. 7, operating lever 25 comprises a rectangular .shet metal stamping having an aperture forming side arms 28-28 and end cross bars 29 and 30, and control lever 26 also comprises a sheet metal stamping having an aperture forming side arms 3l3l and end cross bars 32 and 33. Also as shown in Fig. 7, the upstanding projections 24 on base plate 4 are each formed to provide a pair of oppositely disposed V-shapecl bearing notches 34 and 35 and the side arms 28 of operating lever 25 are provided with ear rojections to for engaging within the bearing notches 36 while the side arms 3| of control lever 25 are provided with ear projections 31 for engaging within the bearing notches 35; The ear projections lit and ill of levers 25 and 26 are yieldingly held within their respective bearing notches 34 and 35 by the over-center springs 2'8 and as shown in Figs. 3 and 4 the rear ends of said springs are attached adjacent opposite ends of the cross bar (it of operating lever 25 and the front ends of said springs are attached adjacent opposite ends of the cross bar (52 of control lever it. For a purpose hereinafter set forth the bearing notches 343 for operating lever 25 are spaced upwardly with respect to the bearing notches 35 for control lever in. As shown in Fig. 2, the cross bar to or operating lever 25 is located above the forwardly extending arms 23 on cell crank levers 2t and upward movement of the rear end of said operating lever is limited by engagement of said cross bar with an adjustable screw stop 39 which is threaded into a projection 4t formed on the front end of insulating base 23. The cross bar 32 or control lever is spaced forwardly with respect to the cross bar 2d of operating lever 26 and upward movement or" the front end of said control lever is limited by stop projections ll formed on the side arms 2d of base plate 6.

The operation oi the aioredescribed snap operating mechanism will be readily understood by reference to 8 and 9. As shown in Figs. i and 8, the of springs ll are normally located above the hearing notches 3d and whereby operating lever 25% is normally held in engagement with its associated screw stop 39 and control lever is normally held in engagement with the stop projections ll on base plate Q. When iront end of control lever 26 is swun downwardly away from the stop projections ii the axes of sprin ii are moved downwardly across the bearing notches 3 3 and lever 25 is thus moved with a snap action away from the screw stop 39 and into engagement with the "forwardly extending arms 23 of hell cranks lid to move bridging contactill out of engagement with. its cooperating stationary contacts against the action of spring ll, as shown in Fig. 9. Downward movement of the front end of operating lever is limited by engagement of the cross bar with the upper face of base plate I} and upon downward movement of said control lever into said limit the axes of springs ll are still located above the bearing notches 35. The over-center springs ll thus act to constanly bias the front end of control lever 26 upwardly and upon release of said lever the same returns under the action of said springs to the position shown in Fig. 8. Upon return ed lever 26 to the position shown in Fig. 8 the axes of springs Eli are moved upwardly across the bearing notches 3 to efiect snap return movement of operating lever into the position shown in Fig. 8 to permit return of bridging contact In to circuit closing position under the action of springs H.

The bridging contact ID of switch unit I is operated by the pressure responsive device 3 through the medium of the snap operating mechanism 2. As shown in Fig. 2, the pressure responsive device 3 includes a flexible metal diaphragm N which is sealed within the opening in a rigid cup member 45 havin a closed tube extension 36 connected thereto. Diaphragm 44 is spaced with respect to the bottom wall of cup member 65 to provide a sealed chamber 41 and said chamber and the tube 36 are filled with a thermal responsive fluid such as methyl chloride. The open end of cup member t5 is provided with an outwardly extending flange of rectangular form and said cup member is secured to the under side of base plate 4 by screws 48 (Fig. 4) which are located at the corners of said flange.

The loading spring ii associated with the pressure responsive device 3 is of coil form and extends upwardly from diaphragm 46 through the opening in base plate 4 and through the apertures in levers Eli and 2s. The lower end of loading spring 6 has a circular cup washer 49 associated therewith which bears against the upper face of diaphragm id, and is operatively connected to control lever 28 of the snap operating mechanism through the medium of a stirrup lit. Cup washer is is formed of sheet metal and is provided with an outwardly extending peripheral flange 5i and an upwardly extending center projection 52 which engages within the opening in loading sprin 6. Stirrup 5b is also formed of sheet metal and comprises a ring-shaped yolre 53 having upstanding arms ml formed on opposite sides thereof and an inwardly extending circular flange o5 formed on the under side thereof. Flange aid is provided with diametrically disposed humps 56 which engage the under side or" the flange hi on cup member 39 and the arms 5d are disposed at right angles to said humps and are provided with slots ol for receiving inwardly extending bearing projections 58 formed on the side arms 36 or control lever it. The upper ends of slots 51] are shaped to provide li shaped surfaces for engaging the top faces of bearing projections SB, and as best shown in Fig. 3 said bearing projections are located in front of the bearing projections Bl whereby the control lever 26 is movable by the stirrup from the position shown in Fig. 4 to the position shown in Fig. 5 under the action oi loading spring 6.

Assuming that the switch is employed to control energization of an electric refrigerator, the tube lli may be secured to the evaporator of the refrigerator and the pressure of the fluid in chamber ll of pressure responsive device 3 will then vary in accordance with changes in the temperature of the evaporator. Thus upon warming of the evaporator the pressure oi the fluid in chamber ll will increase to eiiect expansion of diaphragm do against the action of loading spring During expansive movement of diaphragm M stirrup 50 is maintained in engagement with washer til under the action of springs ill and at predetermined high temperature determined by the opposing force of loading spring ii control lever 2c is moved upwardly into circuit closing position to effect starting of the refrigerator. Upon starting of the refrigerator the pressure of the fluid in chamber ll will decrease due to cooling of the evaporator, and diaphragm 3d contracts under the action of loading spring 8. Upon contraction of diaphragm it th stirrup 50 asvaeav moves therewith and upon a predetermined tem-- perature drop lever 28 is moved downwardly into its circuit opening position to eifect stopping of the refrigerator. As is apparent, variation of the degree of compression of spring varies the temperature values at which the refrigerator is started and stopped. Also adjustment of screw stop 89 varies the position of control lever 25 to vary the point at which said lever is operated during downward movement of control lever 26 from the position shown in Fig. ti toward the position shown in Fig. 5. Adjustment of screw stop 39 therefore varies the differential between the opening and closing pressures of the switch.

Loading spring 6 is adjustable by the knob l which is rotatably supported as hereinafter set forth within an opening 60 in a front plate 6i. Knob l is provided with a circular hub portion 62 having a cam projection 63 formed on the rear end thereof, and loading spring -6 is adjustable by said cam projection through the medium of a pivoted lever 64 and a cam follower B5. Lever 64 is arranged horizontally abovethe loading spring 6 and the same comprises a sheet metal stamping of general Y-shape including spaced side arms 66 which extend rearwardly with respect to loading spring 6 and an arm 67 which extends forwardly with respect to said spring. The rear ends of the arms 68 are provided with v notches all for receiving downwardly struck bearing projections 69 formed on the rear end of the top wall of cover 5 as shown in Fig. 4 and the front end of arm 61 is provided witha tip of arcuate form upon which cam follower 65 is suspended.

Lever be is operatively connected to loading spring 6 by a nut in carried by a screw ll. Nut 90 engages the upper end of loading spring 6 and is shouldered to fit within the same, and screw ll extends upwardly through an opening in lever 64 and is provided with a circular flange 52 which bears against humps l3 formed on the underside of said lever. Cam follower t5 comprises a sheet metal stamping having an opening "Hi for receiving the cam projections 53 and a slot 15 on the upper end thereof for receiving the arcuate tip on the front end of arm Bl of lever 54. The lower end of cam follower 65 is formed to provide an upwardly extending cam engaging projection l6 and a downwardly extending guide tongue ll which engages within a vertically disposed slot formed by projections 58 on the front end of base plate 4.

lit will be noted in connection with the foregoing that lever 68 and cam follower 65 are biased upwardly under the action of loading r spring it and the projection M5 on said cam follower is thus held in contact with the cam projection d3 of knob l. As shown in Fig. 6, cam projection $3 is provided with a cam surface 80, and as is apparent said cam surface provides for vertical movement of cum follower 65 and lever 64 between given upper and lower limits upon rotation of knob l in opposite directions through a given range. Thus when it is desirable to increase the pressures at which the switch is operated the cam projection 63 is rotated clockwise as viewed in Fig. 6, which moves the cam follower 65 downwardly, thereby compressing the loading spring 6 to increase the load on the diaphragm 44. When it is desirable to decrease the pressures at which the switch operates cam projection '63 is rotated counterclockwise by knob l which permits upward movement of cam follower 1 55 for a decrease in the loading effect of spring 6.

As is apparent, loading spring 6 is also adjustahie by the screw ii and in practice said screw is shop adjusted with knob 1 set in a given normal angular position to provide for closure of the switch at a predetermined pressure value. As shown in Fig. 2, the. upper end of screw H is provided with a slot and said screw is thus ac-- cessible for adjustment by means of a screw driver which is insertable through an opening 8|- in the top wall of cover 5. As shown in Fig. 2, the differential adjusting screw 39 extends. upwardly through an opening in the top wall of cover 5 and the upper end thereof is provided with a slot to render the same adjustable by means of a screw driver. Screw 39 is shop adjusted to provide a predetermined difierential between the opening and closing pressures of the switch and after such adjustment an arm 82'is fixed to the upper end of said screw. Arm 82 cooperates with a stop 83 fixed to the upper wall of cover 5 to permit a limited degree of adjustdifierential.

As hereinbefore stated, knob 7 is rotatably supported within an opening 60 in the front plate 8|. As shown in Figs. 3 and 4, plate BI is held in assembled position upon the device by engagement of spaced upwardly extending projections 85 formed on the lower edge of said plate within openings 86 formed in the front end of base plate 4, and by screws 86 which extend through openings in the top wall of casing 5 into tapped openings in projections 87 formed on the upper edge of saidfront plate. As is apparent, knob l is biased upwardly under the action of loading spring 6 and the hub portion 62 thereof is thus held in engagement with the upper edge of the opening 80 in plate ti. As shown in Fig. 2, knob l is held in assembled position upon plate ti by engagement of said plate within a circumferential groove 39 formed in the hub portion 62. The opening lid in face plate 6| is of such dimensions that knob l may be moved downwardly into a position wherein groove 89 is disengaged from plate 65 and said knob may thus be removed or assembled from the front of the device. As shown in Figs. 1, 2 and 6 the hub portion 62 of knob 'i' is provided with a radial projection 90 which cooperates with an inwardly extending stop an upstanding cam projection 93 (Fig. 7) and upon rotation of knob l in a clockwise direction (Fig. 6) into the limit wherein projection 90 on said knob engages the stop projection 9i cam projection 93 is engaged by lug 92 to move switch lever 26 into circuit opening position fordef rosting of the refrigerator. During final movement of knob "i into said limit the high point of cam surface 8i? is moved in a clockwise direction (Fig. 4) beyond the projection 16 on cam follower 65 and said cam follower is then held in its lower limit by a circular cam face 95 on cam projection 63.

What I claim as new and desire to secure by Letters Patent is:

1. In a circuit controlling device, in combination, a housing open at opposite ends and comprising a base plate and a U-shaped cover member, a control switch having a contact carrying insulating base mounted within the opening in one end of said housing, a pressure responsive device mounted upon said base plate and having an associated loading spring located within said housing, said loading spring being of coil form and being arranged with its axis substantially perpendicular to said base plate, a snap operating mechanism for said switch mounted within said housing and operable by said pressure responsive device to effect opening and closure of said control switch, a face plate mounted upon said housing on the end opposite said contact carrying base and a manual control element rotatably mounted upon said face plate for adjusting said loading spring to vary the pressure values at which said control switch is opened and closed.

2. In a circuit controlling device, in combination, a housing open at opposite ends and comprising a base plate and a U-shaped cover, a control switch having acontact carrying insulating base mounted within the opening in one end of said housing, a pressure responsive device mounted upon said base plate and having an associated loading spring located within said housing, said loading spring being of coil form and being arranged with its axis substantially perpendicular to said base plate, a snap operating mechanism for said switch mounted within said housing and operable by said pressure responsive device to effect opening and closure of said control switch, a face plate mounted uponsaid housing on the end opposite said contact carrying base, and a manual control element mounted upon said face plate and rotatable in opposite directions between given extreme positions to adjust said loading spring for variation of the pressure values at which said control switch is opened and closed, said snap operating mechanism being also operable by said control member upon movement thereof into one extreme position to efiect opening of said control switch.

3. In a circuit controlling device, in combination, a housing open at opposite ends and comprising a base plate and a U-shaped cover, a control switch having a contact carrying insulating base mounted within the opening in one end of said housing, a pressure responsive device mounted upon said base plate and having an associated loading spring located within said housing, a snap operating mechanism for said switch mounted within said housing and operable by said pressure responsive device to effect opening and closure of said control switch, a face plate detachably mounted upon said housing on the end opposite said contact carrying base and a manual adjusting element detachably mounted upon said face plate and rotatable in opposite directions between given extreme positions, said control element having a cam associated therewith for adjusting said loading spring to vary the pressure values at which said control switch is opened and closed and said control element also having a projection thereon for operating said snap operating mechanism to effect opening of said control switch upon movement of said control element into one of its extreme positions.

d. In a circuit controlling device, in combination, a housing open at opposite ends, a control switch including an insulating contact carrying base mounted within the opening in one end of said housing, a pressure responsive device mounted uponone of the walls of said housing and having a loading spring associated therewith located within said housing, a snap operating mechanism for said switch mounted within said housing and operable by said pressure responsive device to eilect opening and closure of said control switch, a face plate detachably mounted upon said housing on the end opposite said base, and means for adjusting said loading spring including a manual control member rotatably mounted upon said face plate and having a cam associated therewith, a pivoted lever mounted within said housmg and adjustable by said cam to vary the loading effect of said spring and a screw adjustment associated with said lever and accessible from the exterior of said housing for varying the loading efiect of said spring independently of said cam.

5. In a circuit controlling device, in combination, a housing open at opposite ends, a control switch including an insulating contact carrying base mounted within the opening in one end of said housing, a pressure responsive device mounted upon one of the walls of said housing and hav ing a loading spring associated therewith located within said housing, a snap operating mechanism for said switch mounted within said'housing and operable by said pressure responsive device to effect opening and closure of said switch, a face plate detachably mounted upon said housin on the end opposite said control switch, a manual adjusting member mounted upon said face plate and rotatable in opposite directions between given extreme positions, said snap operating mechanism being operable by said adjusting member upon movement thereof into one extreme position to effect opening of said switch and said adjusting member having a cam associated therewith, a piv oted lever mounted within said housing and adjustable by said cam to vary the loading effect of said spring, and a screw adjustment associated with said, lever and accessible from the exterior of said housing for varying the loading effect of said spring independently of said earn.

6. In a circuit controlling device, in combination, a switch biased toward circuit closin position, a pivoted operating lever for said switch movable into a given extreme position to effect opening of said switch and into an opposite extreme position to permit closure of said switch, a pivoted control lever and a spring operating connection between said levers acting upon movement of said control lever out of and into a given normal extreme position to effect operation of said operating lever with a snap action between its switch opening and switch closing positions, said control lever being constantly urged by said spring operating connection toward said normal extreme position.

7. In a circuit controlling device, in combination, a switch biased toward circuit closing position, a pivoted operating lever for said switch movableinto a given extreme position to effect opening of said switch and into an opposite extreme position to permit closure of said switch, a pivoted control lever, a spring operating connection between said levers acting upon movement of said control lever out of and into a given nor- ;mal position to effect movement of said operating lever with a snap action between its switch opening and switch closing positions, said control 1ever being constantly urged by said spring operating connection toward its normal extreme position, a loading spring tending to move said control lever out of normal position and a fluid condition responsive device for operating said control lever in opposition to said loading spring.

opening in one end of said housing, a condition responsive device mounted upon said base plate and having an associated loading spring located within said housing, a snapoperating mechanism for said switch mounted within said housing and g operable by said condition responsive device to eifeet opening and closure of said control switch, a face plate mounted upon said housing on the end opposite said control switch and a manual control element rotatably mounted upon said face plate for adjusting said loading spring to vary the pressure values at which said control switch is opened and closed, said manual control element being detachably mounted upon said face plate and being held in assembled position thereon under the action of said loading spring.

9. In a circuit controlling device, in combination, a control switch, a pivoted lever movable into a given extreme position to efiect opening. of said switch and into an opposite extreme position to permit closure of said switch, a second pivoted lever, a spring operating connection between said levers acting upon movement of said second pivoted lever out of and into a given normal extreme position to effect operation of said first lever with a snap action between its switch opening and switch closing positions, said second lever being constantly urged by said spring operating connection toward said normal extreme position, a temperature responsive device for controlling said second lever, said second lever being movable out of said normal position independently of said temperature responsive device, and a manual adiusting element rotatable in opposite directions,

between given extreme positions to adjust maid temperature responsive device and also adapted upon movement into one of its extreme positions to move said second lever out of normal position for opening of said control switch independently of said temperature responsive device. 10. A control apparatus comprising in combination, a member movable in opposite directions in response to changes in a condition to be controlled; a snap acting control mechanism including a snap member and a spring'tor imto be controlled; a snap acting control mechanism including a snap member and a spring for imparting movement to the snap member; a lever movable into and out of engagementwith the first mentioned member, said spring being connected with the lever to continually urge the lever into engagement with the first mentioned member for causing, the lever to follow the movement of the first mentioned member when the latter moves in either direction, said spring causing snap movement of said snap member in one direction and then the other when the lever is moved in opposite directions; and means operated manually for causing disengagement of the lever and the first mentioned member and for maintaining the lever in its disengaged position regardless of movements of the first mentioned member.

12. A control apparatus comprising, in combination, an ladjustable device movable m opposite directions in response to changes in a condition to b controlled, a snap acting control mechanism including a snap member and a spring for imparting movement to said snap member, a lever movable into and out of engagement with said device, said spring being connected to said lever to continuously urge said lever into engagement with said device to cause said lever to follow the movement of said device when th latter moves in either direction, said spring causing snap movement of said snap memberin one direction, and then the other when said lever is moved in opposite directions, an adjusting mechanism for said de-' vice including a manual element movable in opposite directions between given extreme positions, and means associated with said manual element and acting upon movement thereof into one of its extreme positions to disengage said lever from said device and to maintain said lever in its disengaged positionregardless of movements of said device. r, e

parting movement to the snap member; a lever movable into and out of engagement with the first mentioned member, said spring be'ing connected with the lever to continually urge the lever into engagement with the 'flrst mentioned member for causing" the lever to follow the movement of the first mentioned member when I bination. a member movable in opposite directions in response to changes in a condition 13., A control apparatus comprising, in combination, a device movable in opposite directions in response to temperature variations, and having an adjustable loading spring associated therewith, a control switch, a snap operating mechanism for said switch including a control member movable onto! and into a given extreme position to effect snap opening and snap closure, of said control switch, said control member being movable into and out of engage'ment with said device and being biased toward said extreme position to continuously urge the same into engagement with said device for movement with said device when the latter moves in either direction, a manual control element movable in opposite directions between given extreme positions to adjust said loading spring for variation of the temperature values at which said switch is opened and closed, and

means associated with said control element and acting upon movement thereof into a given position to cause disengagement of said operating member from said device and to maintain said operating member in its disengaged position regardless of movement of said device.

CLYDE F. ROBBINS.

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