US1988848A

US1988848A - Circuit controlling device

Info

Publication number: US1988848A
Application number: US514363A
Authority: US
Inventors: Clarence W Kuhn
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1931-02-09
Filing date: 1931-02-09
Publication date: 1935-01-22
Anticipated expiration: 1952-01-22

Description

Jan. 22, 1935. c. w. MN 1 ,988,

- C IRGUIT CONTROLLING DEVICE Filed Feb. 9, 1931 s snets-Sneet 17 f a g s 1 2s 14z 14zk 1a4---- /-1zr 109 a 445 f g -105 I N 141 147 145 10a Jan. 22, 1935. c. w. KUHN CIRCUIT CONTROLLING DEVICE Filed Feb. 9, 1931 3 Sheets-Sheet 2 w .4 51 19 zo a'w 51 I 4?.

Jan. 22, 1935. c. w. kuHN 1,988,848

CIRCUIT CONTROLLING DEVICE Filed Feb. 9, 1951 5 Sheets-Sheet 3 paw 10V flgwio if 184 L. Q7 1% Patented Jan. 22, 1935 omcurr oouraoLmvo DEVICE Clarence W. Kuhn, Milwaukee, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application February 9, 1931, Serial No. 514,363

22 Claims.

6 of the household type.

In refrigerators of the household type refrigeration is usually accomplished by a compressor driven by an electric motor and automatic means is usually provided for starting and stopping the motor to maintain the temperature within the refrigerator between selected values. Also such refrigerators are usually provided with overload protective means for automatically interrupting the motor circuit if, the motor .becomes stalled or overloaded and with. manually controlled means for'rendering the motor inoperative to effect what is known as defrosting.

It has heretofore been proposed to aggregate in a single unit the several elements necessary to effect control of electric refrigerators in the manner above set forth. However, as heretofore constructed such units were provided with separate manual adjustments for varying the temperature values at which the refrigerator motor is started and stopped, for resetting the overload protective means and for rendering the motor inoperative to provide for defrosting.

The present invention has among its objects to provide an improved control unit for electric refrigerators including a single control element which is adjustable to vary the temperature values at which the motor is started and stopped and which is also adjustable to reset the over- ,load means and to effect stopping of the motor for defrosting.

Another object is to provide a refrigerator controller of the aforesaid character consisting of control parts which can be assembled in various relations with respect to each other to suit the space conditions within the refrigerator.

Another object is to provide an improved refrigerator controller of the aforesaid character having its parts arranged whereby the same are readily accessible for inspection or repair.

Another object is to provide a refrigerator controller having an improved temperature responsive device associated therewith which can be readily adjusted to maintain the temperature within the refrigerator between selected values. Another object is to provide a refrigerator controller including a single switch which is. adapted to be opened automatically to protect the refrigerator motor against overloads, and which is also adapted to be controlled manually to stop said motor for defrosting.

Various other objects and advantages of the inventio will hereinafter appear.

The accompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification without departing from the spirit and scope of the appended claims.

In the drawings,

Figure 1 is a side elevational view partly in section, of a refrigerator having a control device embodying the invention associated therewith;

Fig. 2 is a side elevational view of a control device embodying the invention, the enclosing cover being shown in section;

Fig. 3 is a front view of the control device shown in Fig. 2;

Fig. 4 is a sectional view of a temperature responsive switch shown in Figs. 2 and 3;

Fig. 5 is a fragmentary sectional view similar to that shown in'Fig. 4, illustrating certain of the switch parts in another position;

Fig. 6 is a perspective view of a bracket and a lever shown in Fig. 4;

Fig. 7 is a sectional view on line 7-'7 of Fig. 4;

Fig. 8 is a sectional view on line 8-8 of Fig. 4;

Fig. 9 is a rear elevational view of a combined overload and defrosting switch shown in Figs. 2 and 3;

Fig. 10 is a view similar to Fig. 9 illustrating the switch in another position;

Fig. 11 is a sectional view on line 1111 of Fig. 9;

Fig. 12 is a sectional view of a starting relay shown in Fig. 2;

Figs. 13 and 14 are plan views of the relay shown in Fig. .12 illustrating different contact and terminalarrangements for such relay;

Fig. 15 is a sectional view on line l5--15 of Fig. 14, and

Figs. 16 and 17 are diagrammatic views illustrating different circuit arrangements for the control device.

Referring to Fig. l, the same illustrates arrefrigerator comprising a casing 1 having a machine compartment 2 in the lower part thereof which contains a motor driven compressor 3 and having a cooling compartment 4 in the upper part thereof which contains an expansion unit 5. Expansion unit 5 and compressor unit 3 are connected in the usual manner by high and low pressure pipes for circulation of a refrigerant, and in the embodiment illustrated said compressor unit is controlled by a unit 6 mounted within a ventilating duct 7 located at the rear of casing 1 and extending upwardly from the machine compartment 2.

'As shown in Figs. 2 and 3, control unit 6 includes a temperature responsive device 8, an electroresponsive starting relay 9 and an electrothermal overload device 10. As hereinafter set forth device 8 is adapted to start and stop the driving motor upon predetermined temperature values within the refrigerator and the same is adjustable by a knob 11 (Fig. 1) to vary the temperature values at which the motor is started and stopped. Also as hereinafter set forth the overload device 10 is adapted to be reset by knob 11 and is operable by said knob to stop the driving motor for defrosting.

The construction and operation of the above mentioned control elements will now be more fully described.

The temperature responsive device 8 is provided with a switch 13 for controlling the line connections of the driving motor. Said switch is provided with a pivoted operating lever 14 which is under the control of a temperature responsive element of the well known sylphon type comprising a bellows 15 which. is connected to a closed pipe extension 16 to be arranged within the cooling compartment of the refrigerator. Pipe extension 16 contains a fluid, as for example methyl chloride and upon temperature changes within the cooling compartment the temperature of the fluid within said extension varies to effect expansion and contraction of bellows 15. Upon an increase in temperature within the cooling compartment bellows 15 expands and moves operating lever 14 outwardly against the action of an associated spring 17 (Fig. 4) .and upon a predetermined maximum temperature value said lever moves into a posi tion wherein the same effects closure of switch 13 to start the driving motor. Upon a decrease in temperature within the cooling compartment bellows 15 contracts to permit inward movement of lever 14 under the action of spring 17 and upon a predetermined minimum temperature value said lever moves into a position wherein the same effects opening of switch 13 to stop the driving motor.

In connection with the foregoing it should be noted that since the pressure within the refrigerator system varies in accordance with the temperature values, switch 13 can be controlled in the required manner by subjecting bellows 15 to pressure variations As shown in Fig. 4 bellows 15 is secured at its inner end by a nut 18 within an opening pro-. vided in an inverted L-shaped bracket 19 and the outer end of said bellows seats within a suitably formed recess in the inner face of lever 14. The upper end of lever 14 is provided with an inwardly extending projection 20 and as shown in Fig. 6 the inner end of said projection is provided with a T-shaped tongue 21 adapted to be inserted into an opening 22 in bracket 19 to pivotally secure said lever to said bracket. As shown in Fig. 6 tongue 21 is adapted to interlock with shoulders 23--23 formed on the lower edge of opening 22 in bracket 19 and the lower edge of said opening is shaped to provide a knife edge bearing 24 for engaging the under side of the neck portion of said tongue as shown in Fig. 4. Also as shown in Fig. 6 the inner end of projection 20 orflever 14 is shaped to provide knife edge bearings ,25-25 for engaging the front face of bracket 19 on opposite sides of opening 22. The lower end of lever 14 is provided with an inwardly extending projection 26 having a forked portion 27 on the end thereof for receiving a downwardly extending projection 28'on the lower end of bracket 19. As shown in Fig. 6 the forked portion 27 of lever 14 is shaped to provide shoulders 29-29 and 30-30 for engaging the front and rear faces of projection 28 on bracket 19 to limit pivotal movement of said lever in opposite directions.

As hereinbefore stated lever 14 has a spring 17 associated therewith which opposes outward movement thereof by bellows 15. Spring 17 is arranged between lever 14 and bracket 19 and is held under compression between a U-shaped stirrup 31 fixed to said lever and a nut 32 associated with a screw 33. Stirrup 31 is arranged within an opening 34 in lever 14 (Fig. 6) and the same is provided with outwardly bent portions on the extremities thereof which are secured to the front face of said lever by welding. Nut 32 is arranged between a pair of washers 35-36 which are clamped to said nut by a screw 37 and as shown in Figs. 2 and 4 said washers are provided with projections 38 and 39 which extend upwardly into a recess 40 in the upper leg of bracket 19 to fix said nut against rotation. Screw 33 extendsthrough an opening in bracket 19 and has an enlarged head 42 on the inner end thereof which abuts the rear face of said bracket. The head 42 of said screw is adapted to be coupled by a suitable shaft to the adjusting knob 11 shown in Fig. 2 and as is apparent said screw is thus rotatable by said knob to move nut 32 inwardly or outwardly for variation of the degree of compression of spring 17.

As shown in Fig. 8 the switch 13 of the device is provided with an insulating base 45 which is secured to bracket 19 by screws 46. A pair of

terminal plates

47 and 48 are secured to the front face of said base and the former plate has a spring contact 49 associated therewith which is biased to engage the latter plate. Spring contact 49 is provided with an operating pin 50 which is formed of insulating material and is slidably mounted within an opening in base 45. The inner end of said pin extends into a recess 51 in the rear face of insulating base 45 and said recess contains a snap operating mechanism which is associated with the actuating lever 14.

The snap operating mechanism includes an inverted U-shaped plate 52, the legs of which are provided with knife edge ends which seat within recesses 53 (Fig. 5) formed in the upper face of the forked portion 27 of lever 14. The upper end of plate 52 is connected by a tension spring 54 to a pin 55 which is located immediately below the lower end of lever 14 and is secured within an opening in bracket 19 by a nut 56. Outward movement of the upper end of plate 52 is limited by engagement thereof with the face of recess 51 in base 45 and inward movement of the upper end of said plate is limited by engagement thereof with a screw 57 which is threaded within an opening in bracket 19. Forv a purpose hereinafter set forth screw 57 is adjustable with respect to bracket 19 and to facilitate adjustment thereof the same is provided with a recess 58 for receivinga' suitable adjusting tool which can be inserted into saidan opening for receiving said screw and the lower end of which is fixed to bracket 19 by the nut 56 associated with pin 55.

The operation of the aforedescribed device will now be more fully set forth. When operating lever 14 is moved to a position wherein the pivotal axis of plate 52 is located to the left of the axis of spring 54 plate 52 is held in the position shown in Fig. 5. With plate 52 in this position the pin 50 isheld in a projected position to maintain spring contact 49 of switch 13 out of engagement with terminal plate 48. As hereinbefore stated switch 13 controls the line connections for the driving motor and when the parts assume the position shown in Fig. 5 the driving motor is stopped. When the driving motor is stopped the temperature within the refrigerator tends to increase and when such te nperature increases to a selected value determined by the degree of compression of spring 17, bellows 15 moves lever 14 outwardly against the action of said spring into a position wherein the pivotal axis of plate 52 is located to the right of the axis of spring 54. Plate 52 is then moved with a snap action by spring 54 from the position shown in Fig. 5 to the position shown in Fig. 4 and permits spring contact 49 to move into engagement with terminal plate 48 to start the driving motor of the refrigerator. The temperature Within the refrigerator then decreases and upon a predetermined temperature drop within the refrigerator bellows 15 permits lever 14 to move inwardly under the action of spring 17 into a position wherein the pivotal axis of plate 52 is located to the left of the axis of spring 54. Plate 52 is then moved with a snap action by spring 54 from the position shown in Fig. 4 into the position shown in Fig. 5 and opens the spring contact 49 of switch 13 to stop the driving motor.

As hereinbefore stated the temperature value at which the driving motor is started is determined by the degree of compression of spring 17, and as is apparent such temperature can be increased or decreased as desired by adjustment of screw 33. The device is also adjustable by screw 57 to provide for variation of the range of temperature drop which is required to effect stopping of the driving motor. As is apparent, adjustment of screw 57 outwardly advances the point at which switch 13 is opened during'movement of lever 14 inwardly from the position shown in Fig. 4 to thereby decrease the range of temperature drop required to eilect stopping of the driving motor, while inward adjustment of said screw has a reverse effect.

Starting relay 9 is provided with a spring contact 65 arranged upon the upper face of an insulating plate 66 and having its inner end secured to said plate between insulating

bushings

67 and 68 by a bolt 69. Plate 66 is mounted upon a C-shaped bracket 70 by screws 71? and said plate carries a solenoid having an operating winding 73 fixed to the lower face of said plate and a plunger 74 operativelyconnected to the outer end of spring contact 65.

Winding 73 is wound upon an insulating spool 75 having a cenQ'al opening therein for receiving plunger 74, and said spool is secured to a magnetic washer 76 which is fixed to the under face of insulating plate 66 by screws 77 shown in Fig. 13. Insulating spool 75 is secured to washer 76 by a magnetic plug 78 which is threaded into said washer and is provided with an enlarged head for engaging a shoulder provided on the upper end of said spool within the opening therein. The lower end of plunger 74 is weighted by a flange portion 79 and said plunger has an insulating pin 80 mounted upon the upper end thereof which is slidable within an opening in plug 78. The outer end of spring contact 65 is provided with an opening for receiving pin 80 and said pin has an insulating washer 81 mounted upon the upper end thereof for engaging the upper face of said spring contact.

Spring contact 65 is normally held in the position shown in Fig. 12 by plunger 74 and is biased to move upwardly from such position upon upward movement of said plunger into its attracted position. To prevent humming of the plunger when the same is moved into its attracted position a rubber washer 82 is mounted upon the upper face of flange 79. Said washer is adapted to engage the lower face of spool 75 to prevent sealing of the upper end of plunger 74 with plug 78. A plurality of relatively thin fabric shims are interposed between washer 82 and the upper face of flange 79, and as is apparent, by varying the number of shims employed the air gap which is maintained between the upper end of plunger 74 and plug 78 may be adjusted to provide for dropping out of the plunger at a selected current value in winding 73. To provide for variation of the current value at which plunger 74 is adapted to move into its attracted position a shim adjustment 81 is associated with washer 81 which provides for adjustment of the normal position of said plunger'with respect to plug 78. 4

The above described relay is designed so that the same can be used to provide suitable connections for different starting arrangements. For one starting arrangement a resistance element 83 is secured to bracket 70 by a bolt 84 and plate 66 is provided with a contact and terminal arrangement shown in Fig. 13. For another starting arrangement the resistance element is omitted and plate 66 is provided with a contact and terminal arrangement shown in Figs. 14 and 15.

In Figs. 13 and 14 plate 66 has a stationary contact 85 fixed to the upper face thereof which is adapted to be engaged by spring contact 65 upon upward movement thereof from the normal position shown in Fig. 12, and in Fig. 14 an additional stationary contact 86 is mounted upon the upper face of plate 66 which is adapted to be engaged by spring contact 65 when the latter is in normal position as shown-in Fig. 15. In Fig. 13 plate 66 has a plurality of

terminal plates

87, 88 and '89 mounted upon the upper face thereof. Terminal plate 87 is electrically connected to the inner end of spring contact65, resistance unit. 82 is connected between

terminal plates

87 and 88, and the operating winding 73 of the relay is connected between stationary contact 85 and terminal plate 89. In Fig. 14 the insulating plate 66 has

terminal plates

90 and 91 mounted upon the upper face thereof and the former plate is electrically connected to the inner end of spring contact 65 while the operating winding 73 of the relay is connected between

terminal plates

90 and 91. In connection with the foregoing it should be noted that insulating within a recess 96 provided in the rear face of an insulating base 97. Said switch has an electrothermally controlled tripping mechanism 98 asswitch without tripping of said mechanism. 10

Switch is provided with a spring contact 99 having its upper end fixed to an L-shaped supporting member 100 and having its lower end biased to engage an L-shaped contact member 101.

Members

100 and 101 are secured to the rear face of insulating base 97 by

screws

102 and 103, respectively, and said screws pass through openings in said base and are threaded into

terminal plates

104 and 105, respectively, mounted upon the front face of said base as shown in Fig. 3.

The electrothermally controlled tripping mechanism 98 includes an electrothermal device 106, a pawl 107 associated with said device and a switch operating lever 108 carried by said pawl. As shown in Fig. 11 electrothermal device 106 includes an electric heater 109 of helical form mounted within a recess 110 in the front face of insulating base 97; a tubular member 111 fixed within an opening in said base and having its outer end surrounded by said heater and a ratchet pin 112 located within said tubular member. The outer end'of ratchet pin 112 is connected to tubular member 111 by a soldered connection 113 and the inner end of said pin is provided with an enlarged toothed head 114 to be engaged by pawl 107.

Pawl 107 is slidably mounted upon the rear face of insulating base 97 within recess 96 and the same has a tooth projection 115 intermediate the, ends thereof for engaging the head 114 of L the ratchet pin. Said pawl and also the ratchet pin 112 are held in position upon insulating base 97 by a plate 116 secured to said base by a screw 117. The lower end of said pawl is provided with a slot 'for receiving a projection 119 upon the rear face of insulating base 97, and the upper end of said pawl is connected to plate 116 by a spring 120. Spring 120 biases pawl 107 downwardly from the position shown in Fig. 9 and also biases the upper end thereof towards the left to hold the tooth projection 115 thereon in engagement with head 114 of the ratchet pin.

Lever- 108 is formed of insulating material and is pivotally secured intermediate its ends to the lower end of pawl 107 by a pin 121. As shown in Fig. 9 the left hand end of said lever is provided with a cam surface 122 for engaging spring contact 99, and is also provided with a, shoulder 123 for engaging the upper edge of stationary contact 101. The right hand end of said lever projects outwardly through an opening 124 in the wall to the right of recess 96, and as shown in Fig. 9 the face 125 at the lower end of said opening provides a stop for engaging the under side of said lever. v

As hereinbefore set forth, spring contact 99 and stationary contact 101 are respectively connected to

terminal plates

104 and 105 mounted upon the front .face of insulating base 97. As shown in Fig. 3 the front face of said insulatingv base also has a terminal plate 126 mounted thereon and one terminal of the electric heater 109 is connected to said plate while the opposite terminal thereof is connected to terminal plate 105. Also as shown in Figs. 2 and 3 the front face of insulating base 97 has a pair of projecting

contact prongs

127 and 127 mounted thereon, the former prong being connected to terminal plate 126 by a connection 128.

The function and operation of the aforedescribed overload and defrosting switch will now be more fully described. The contact prongs 127 and 127 are adapted to be plugged into a suitable receptacle having contacts connected to the supply circuit of the refrigerator, and as hereinafter set forth current is-supplied to the driving "motor through switch 95 and heater coil 109. Normally pawl 107 and operating lever 108 are in the positions shown in full lines in Fig. 9 and upon rotation of said lever from its full line position into its dotted line position the cam. surface 122 thereon moves spring contact 99 out of engagement with stationary contact 101. The driving motor is thus rendered inoperative to provide for defrosting of the refrigerator and after defrosting lever 108 is returned t3 its full line position to permit reclosure of spring contact 99.

If the driving motor becomes stalled or overloaded, heater coil 109 serves to fuse the solder connection 113 of device 106 and the ratchet pin 112 is then released to permit rotation thereof within the tubular member 111. Upon release of said ratchet pin pawl 107 moves downwardly under the action of spring 120 from the normal position illustrated in Fig. 9 to the full line position illustrated in Fig. 10. Upon downward movement of pawl 107 into the full line position illustrated in Fig. 10 lever 108 assumes the position shown in full lines in this figure and the cam surface 122 thereon moves spring contact 99 out of engagement with stationary contact 101 to interrupt the motor circuit. Upon tripping of pawl l07'the shoulder 123 on lever 108 rests upon the upper edge of stationary con tact 101 and said lever is then adapted upon up- Ward movement of the right hand end thereof from the position shown in full lines in Fig. 10 to the dotted line position illustrated in this figure to reset said pawl in the position shown in full lines in Fig. 9. It should be noted that during resetting operation spring contact 99 is held in open position by lever 125.

Lever 108 is normally held in the position shown in full lines in Fig. 9 by a weighted link 130 which is suspended within an opening in the right hand end of said lever. The lower end of said link is adapted to be engaged by a pin 131 which is fixed to the head 42 of adjusting screw 33 associated with the temperature responsive device 8. As is apparent from Fig. 4 pin 131 is adapted to engage the T-shaped tongue 21 on operating lever 14 ofv the temperature responsive device to limit rotation of said screw in opposite directions between the extreme positions illustrated by full and dotted lines in Fig. 9. During rotation of screw 33 into the extreme position illustrated in dotted lines in Fig. 9 pin 131 engages the lower end of link 130 to mpve the same upwardly. Upon movement of pin 131 into the defrosting position illustrated by dotted lines in Fig. 9 lever 108 effects opening of switch 95 for defrosting of the refrigerator, andupon movement of said pin into-the reset position illustrated by dotted lines in Fig. 9 lever 108 is moved into its reset position. Screw 33 of the temperature responsive device is preferably provided with a left hand thread. Thus adjustment of said screw in a clockwise direction (Fig. 9) decreases the degree of compression of spring 17 to decrease the temperature value within the refrigerator at which the driving motor is started, while adjustment of said screw in a counterclockwise direction has a reverse effect.

Referring now to Fig. 16, the above described control unit is shown connected to control the circuit of a single "phase alternating current motor M having a starting winding 135 and a nected to stationary contact 85 of the starting,

1 relay and said relay is provided with the termi switch to stop further refrigerating action.

When the temperature within the refrigerator increases to a given value the temperature responsive switch 13 closes and circuit for the running winding 136 is established extending from line IF through heater coil 109 and switch 95 of the overload and defrosting device to and through the switch 13 of temperature responsive device 8 to stationary contact 85 of the starting relay 9 and thence through the operating winding 73 of saidrelay and the running winding 136 of the motor to line L The inrush of current to the motor immediately causes the winding 73 of the starting relay to effect movement of spring contact 65 into engagement with stationary contact 85 and the starting winding 135 is thenenergized by a circuit extending from line L to stationary contact 85 as already traced, through spring contact 65, through resistance element 83, and thence through the starting winding 135 to line L. When the motor has started the refrigerator compressor and has accelerated to a predetermined speed the current in the operating winding 73 of the starting relay decreases in value sufficiently to permit return of spring contact 65 to normal position. This opens the circuit of the starting winding 135 and the running winding 136 continues operation of .the motor.

As the motor M continues to operate the temperature within the refrigerator is lowered and when the temperature has been lowered to a selected value determined by the setting of the temperature responsive switch 8 said switch opens to interrupt the circuit of the driving motor. Under normal operating conditions the starting and running cycle of the refrigerator is controlled in the manner just described entirely automatically by the temperature responsive switch 8 so as to maintain the temperature of the refrigerator within the desired limits, said limits being adjustable, as hereinbefore set forth, by the knob 11 shown in Fig. 1. Also as hereinbefore set forth the switch 95 of the overload and defrosting device 10 is adapted to protect the motor against overloads and the knob 11 shown in Fig. 1 is operable to reset said switch upon tripping thereof, and is also operable to open the same to stop the motor for the medium of an autotransformer winding 137 and a condenser 138, said transformer winding being connected in series with the starting winding 135 ofthe motor, and said condenser being connected in shunt with said autotransformer winding. The left hand terminals of starting winding 135 and running winding 136 of the motor are permanently connected to contact prong 127 which is connected to line L and upon closure of switch 13 of the temperature responsive device circuit is established from line L through heater coil 109 and switch 95 of the overload and defrosting devicethrough switch 13 to terminal plate 90 through the operating winding 73 of starting relay 9 to theright hand terminal of the running winding 136. The inrush of current to the motor immediately causes the winding 73 of the starting relay to effect movement of spring contact 65 into engagement with stationary contact 85 and line L is then connected to terminal T of the autotransformer winding 137. The motor is then adapted to accelerate and when the same has attained a predetermined speed the current in coil 73 of the starting relay is reduced to a value to permit return of springcontact 65 into engagement with stationary contact 86. This disconnects line L from terminal T of the autotransformer winding and connects such line to terminal T of said transformer winding for running.

In the control unit illustrated the control elements are arranged in a vertical relation, the overload and defrosting switch being arranged above the temperature responsive switch 8 and the starting relay 9 being arranged below the latter switch. As shown in Fig. 2 the supporting bracket 19 of temperature responsive switch 8 is fixed to an L-shaped bracket 140 by screws 141 and the latter bracket is secured by welding to a base member 142 having forwardly extending projections on the upper and lower ends thereof. The insulating base 97 of the overload and defrosting switch is fixed to the face of bracket 140 by screws 143 and the lower leg of the bracket 70 of the starting relay 9 is fixed to the forwardly extending projection on the lower end of base 142 by screws 145. A box-shaped enclosing cover 146 is carried by base 142, said cover being provided with an opening 147 for receiving a receptacle to be plugged on to the prongs 127 and 127' of the overload and defrosting switch. As is apparent the

control elements

8, 9 and 10 can be arranged in relations other than that shown in Figs. '2 and 3 to suit the space conditions within the refrigerator. i

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

1. In a circuit controlling device, in combination, a pair of series connected switches for controlling the circuit, one of said switches being responsive to interrupt and establish said circuit in accordance with predetermined temperature variations in an ambient medium, and the other being responsive upon predetermined overload conditions in said circuit to interrupt'the same, and means including a single control element operable to vary the temperature values at which said first mentioned switch opens and closes said circuit, and also operable to open and close said second mentioned switch at will and to reset the same in closed position upon response thereof.

2. In a controller for electric refrigerators, the combination with a temperature responsive device for controlling the power circuit of the refrigerator to start and stop the refrigerator upon predetermined temperature conditions therein, said device having adjusting means associated therewith for varying the temperature values at which the same effects starting and stopping of the refrigerator, and a cut-out device sepa rate from the former device responsive to interrupt the power circuit of the refrigerator upon given overload conditions in such circuit,

said adjusting means being operable to reset said cut-out device upon response thereof and being also operable to open and close said outout device at will.

3. In a controller for electric refrigerators, the combination with a temperature responsive device for interrupting and establishing the power circuit of the refrigerator upon predetermined temperature conditions within the refrigerator, a cut-out device responsive to interrupt said power circuit upon given overload conditions therein, and means associated with said devices including a single manually adjustable part movable in opposite directions between given extreme positions to vary the temperatures at which said temperature responsive device establishes and interrupts the power circuit of the refrigerator, said part being also movable within a fractional part of its range into and out of one extreme position to open and close said cut-out device at will and to reset the same upon response thereof.

4. In a controller for electric-refrigerators, in combination a switch for controlling the power circuit of the refrigerator, said switch being biased to closed'position, a member operable to open and close said switch at will, and an electro-thermallycontrolled tripping mechanism associated with said member responsive to open said switch upon predetermined overload conditions in said power 'circuit, said member being operable to reset said tripping mechanism and to efiect the aforementioned opening of said switch while said tripping mechanism remains set.

5. In a controller for electric refrigerators, in

- combination, circuit controlling contacts, adjustable power means for effecting cyclic operation of certain of said contacts in response to variations in temperature, thermal overload means for effecting operation of certain of said contacts, said thermal overload means including a thermal element of the solder-type and an elementnormally engaged therewitlt' to be restrained thereby, and manual means to effect adjustment of said power means, resetting-of said overload means following response thereof and setting of certain of said-contacts at will for defrosting while the aforementioned parts 'of said overload means remain engaged, said manual means including a manually operable element and means providing for the aforementioned resetting of said overload means and also for the aforementioned defrosting setting of contacts by adjustments of said manually operable element.

6. In a controller for electric refrigerators, in combination, a temperature responsive device having; contacts for controlling the power circuit of the refrigerator in accordance with temperature conditions within the refrigerator, said device having a manual'adjusting element associated therewith for varying the temperatures at which the same opens and closes said circuit, a normally closed switch for controlling said power circuit and electrothermally controlled tripping mechanism associated with said switch responsive to open the same upon given overload conditions in said power circuit, said tripping mechanism including a part normally operable to open and close said switch at will, and also-operable to effect resetting of said tripping mechanism upon response thereof, said part being so operable by the adjusting element of said temperature responsive device.

7. In a controller for electric refrigerators, the combination with a normally closed switch for controlling the power circuit of the refrigerator, of an element manually operable to open and close said switch at will and to retain it open for defrosting, and electro-thermal tripping mechanism of the solder type associated with said element and responsive to open said switch upon predetermined overload conditions in said power circuit, said element being operable to reset said tripping mechanism and tomaintain said switch in open position during resetting of said tripping mechanism.

8. In a control device for electric refrigerators, in combination, a pair of series connected switches for controlling the power circuit of the refrigerator; one of said switches having pressure responsive operating means associated therewith and the other being responsive upon predetermined overload conditions in said circuit to interrupt the same, and means including a single control element operable to vary the pressure values at which said first mentioned switch opens and closes said circuit and also operable to open and close said second mentioned switch at will and to resetthe same in closed position upon response thereof.

9. The combination with a control structure having pressure responsive actuating means, a

thermal cutout device and an adjustment con-- trol device, of a unit control comprising a knob for actuating the adjustment control device, 'said knob being'operatively connected with the thermal cutout device to reset the same follow? ing response thereof, andsaid knob affording the aforestated dual control upon movement thereof in a single plane.

10. In a controller for electric refrigerators, in combination, circuit controlling contacts, adjustable power means for effecting cyclic operation of certain of said contacts in response to variations in temperature, thermal overload means for effecting operation of certain of said contacts, a manual element and means which afford by movement of said element to different positions a low temperature adjustment, a defrosting adjustment and resetting of said,thermal overload means after response thereof the defrosting and resetting positions of said element being adjacent.

11. In a controller for electric refrigerators, in combination, circuit controlling contacts, adjustable 'power means for. effecting. cyclic operation of certain of said contacts in response to variations in temperature, thermal overload means having normally engaged parts disengageable on overload for effecting operation of certain of said contacts, a manual element and means which afford by movement of said element to different positions adjustment ofetheaforementioned cyclic operation, resetting of said thermal overload means after response thereof and opening of circuit by said contacts at will while said parts of said overload means remain engaged.

12. In a controller for electric refrigerators, in

combination, circuit controlling contacts, ad-

justable power means for effecting cyclic operation of certain of said contacts in response to variations in temperature, thermal overload means for effecting operation of certain of said contacts, a manual element and means which afford by movement of said element to different positions a low temperature adjustment, a defrosting adjustment and resetting of said thermal overload means with retention of certain of said contacts in open position during resetting of said thermal overload means.

13. In a controller for electric refrigerators, in combination, circuit controlling contacts, adjustable power means for operating certain of said contacts cyclicly in response to temperature variations, thermal overload means for effecting operation of certain of said contacts, a manual element and means affording by movement of said element to a given position a certain adjustment'ofthe aforementioned cyclic operation}.

to another given position circuit interruption by said contacts while that part of said overload means sensitive to thermal changes remains set and to another given position restoration of circuit control to said power means and said thermal overload means.

14. In a controller for electric refrigerators, in

combination, circuit controlling contacts, power means for operating certain of said contacts cyclicly in response to temperature variations, thermal overload means to effect operation of certain of said contacts to render operation of said power means ineffective for circuit control pending resetting of said thermal overload means, a manual element and means affording by movement of said element while said thermal overload means remains set operation of certain of said contacts at will and resetting of said thermal overload means after response thereof.

15. In a controller for electric refrigerators, in combination, circuit controlling contacts, power means for operating certain of said contacts cyclicly in response to temperature variations,

- thermal overload means to effect operation of certain of said contacts to render operation of said power means ineffective for circuit control pending resetting of said thermal overload means, a manual element and means affording by movement of said element operation of certain of said contacts at will, resetting of said thermal overload means and operation of certain of said contacts to circuit closing position free from interference with immediate opening thereof if overload occurs upon initial closure of circuit.

16. In a controller for electric refrigerators, in combination, circuit controlling contacts, operating means for certain of said contacts comprising sylphon bellows and an opposing spring continuously active and alone constituting the major load on saidbellows, a manual device for adjusting said spring to vary an operating characteristic of said means and means operable by said manual device to effect defrosting setting of the controller.

17. In a controller for electric refrigerators, in combination, circuit controlling contacts, operating means for certain of said contacts comprising sylphon bellows and an opposing spring continuously active and alone constituting the major load on said bellows, thermal overload means to effect circuit opening operation of certain of said contacts, a manual element and means affording by adjustments of said manual element adjustment of said spring to vary an operating characteristic of the first mentioned means and resetting of said thermal overload means after response thereof.

18. In a controller for electric refrigerators, in combination, circuit controlling contacts, operating means for certain of said contacts comprising sylphon bellows and an opposing spring continuously active and alone constituting the major load on the bellows, thermal overload means to effect circuit opening of certain of said contacts and associated external manual means to effect resetting of said thermal overload means after response thereof and to effect selectively lowering of the refrigerator temperature and defrosting of the refrigerator, said manual means comprising a single element to effect such selective temperature lowering and defrosting and further comprising means which enables said element to adjust said spring for accomplishment of certain of its aforerecited functions.

19. In a control system for the motor of an automatic refrigerator, the combination with a housing, of a temperature responsive mechanism arranged in said housing, means arranged to be operated by said responsive mechanism for controlling the circuit of the refrigerator motor at one point therein, a switch operable to control said circuit at another point therein, safety mechanism automatically operative when an excess flow through said circuit occurs to move said switch to open said circuit, terminals for said circuit carried by said housing, and manual adjusting means associated with said temperature responsive mechanism and having an element external of said housing by means of which an operating characteristic of said mechanism may be varied at will.

20. In a control system for the motor of an automatic refrigerator, the combination with a housing, of a temperature responsive mechanism arranged in said housing, said mechanism including bellows and an opposing spring continuously active and alone constituting the major load on the bellows, means within said housing arranged to be operated by said responsive mechanism for controlling the circuit of the refrigerator motor at one point therein, a switch within said housing operable to control said, circuit at another point therein, safety mechanism within said housing automatically operative when an excess flow through said circuit occurs to move said switch to open said circuit, and manual means operable from the to open the latter against its bias during final movement of said lever into one extreme position and to permitreclosure of said switch during initial reverse movement of said lever away from such extreme position, an overcenter spring for moving said lever in opposite directions between said extreme positions with a snap and a fluid condition responsive device acting upon said spring to effect snap operations of said lever.

.22. In a controller for electric refrigerators, in combination, a control switch biased to closed position, a lever movable between extreme positions and operativ ely associated withsaid switch to open the latter against its bias during final movement of said lever into one extreme position and to permit reclosure of said switch during initial reverse movement of said lever away from such extreme position, an over-center spring for moving said lever in opposite directions between said extreme positions with a snap, a fluid condition responsive element acting upon said spring to efiect snap operation of said lever, spring means acting in opposition to said pressure responsive element, a range adjusting element for varying the tension of said spring means and a differential adjusting element associated with said lever for varying one of the limits thereof.

CLARENCE W. KUHN.