US3190988A

US3190988A - Room thermostats

Info

Publication number: US3190988A
Application number: US235915A
Authority: US
Inventors: Marvin M Graham; John W Wright; Ralph E Drummond
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1962-02-28
Filing date: 1962-11-05
Publication date: 1965-06-22
Anticipated expiration: 1982-06-22
Also published as: CH408480A; GB999653A; GB1021268A

Description

June 22, 1965 M. M. GRAHAM ETAL 3,190,933

ROOM THERMOSTATS} Filed Nov. 5, 1962 I 9 Sheets-Sheet 1 I INVENTORS.

. MARVIN u. GRAHAM JOHN v1 WRIGHT y RALPH E. onuuuouo 77 M um, @6 41), Ma.

ATTORNEYS 1 M. M. GRYAHAM ETAL 3,190,988

June 22, 1965 ROOM THERMOSTATS 9 Sheets-Sheet 2 Filed Nov. 5, 1962 FIG.4

Fl G. 6

INVHVTORS MRWN H. GRAHAM ATTORNEYS 8 JOHN w. mam

Y RALPH E. muuuouo June 22, 1965 M. M. GRAHAM ETAL 3,190,933

noon wnnauosuws Filed Nov. 5, 1962 9 Shuts-Sheet 3 INVENT 5. MARVIN M. GRA M JOHN W. WRIGHT By RALPH E. onurmoun 71%, am, 436 4 zw A TTORNE Y5.

M. M. GRAHAM ETAL 3,190,988

June 22, 1965 ROOM mmosm'rs 9 Sheets-Sheet 4 Filed Nov. 5, 1962 INVENTOR-S'.

MARVlN RAHAM JOHN VI. GHT BY RALPH E. DRUMMOND ATTORNEY June 22, 1965 M. M. GRAHAM ETAL 3,190,988

ROOM THERMOSTATS Filed Nov. 5, 1962 9 Sheets-Sheet 5 gl 33s IN VEN TORS.

MARVIN M. GRAHAM JOHN W. WRIGHT RALPH E. DRUMMOND A TTORNEYS.

June 22, 1965 M. M. GRAHAM ETAL 3,190,938

ROOM THERMOSTATS Filed Nov. 5, 1962 9 Sheets-Sheet a FIG. I6 FIG. |7

FIG. I8

INVENTOR-S. 445 MARVIN M. GRAHAM JOHN W. WRIGHT RALPH E. DRUMMOND A TTORNE Y6.

.June 22, 1965 M. M. GRAHAM ETAL ROOM THERMOSTA'IS 9 Sheets-Sheet '7 Filed Nov. 5, 1962 INVENTORS. MARVIN M. GRAHAM JOHN W. WRIGHT BY RALPH E. DRUMWND v hlbul, a

- ATTORNEYJ.

June 22, 1965 M. M. GRAHAM ETAL 3,190,988

ROOM THERMOSTATS 9 Sheets-Sheet 8 Filed Nov. 5, 1962 INVENTORS MARVIN M GRAHAM BY JOHN W. WRIGHT R flaw ALPH E. DRUMMQND 4 3 A TTORNE YS June 22 1965 M. M. GRAHAM: ETAL 9 Sheets-Sheet 9 Filedi NOW. 5, 1962 FIG. 27

FIG. 29

FIG. 28

INVENTORS MARVIN M. GRAHAM JOHN W WRIGHT RALPH E. DRUMMOND ATTORNEYS United States Patent 3,190,988 ROUM THERNIOSTATS Marvin M. Graham, San Pedro, John W. Wright, Long Beach, and Ralph E. Drummond, Bell, Califi, assignors to Robertshaw Controls Company, a corporation of Delaware Filed Nov. 5, 1962, Ser. No. 235,915 20 Claims. (Cl. 200-122) This application is a continuation-in-part of copending application Serial No. 176,282, now abandoned, filed February28, 1962. r

This invention relates to condition responsive control devices and more particularly to thermostats for controlling heating and cooling systems.

It is an object of this invention to provide a series of thermostats having interchangeable parts and components for adaptation with a wide selection of heating and cooling systems.

A further object is to provide a thermostat subassembly which is capable of interchangeable use as a component of several thermostats.

Another object is to provide a thermostat sub-base of integral, rugged construction having supporting elements so arranged as to be capable of supporting a wide variety of arrangements of thermostat components.

Still another object is to provide a thermostat subassembly including a bimetal actuated switch in which the bimetal may be accurately calibrated with respect to the switch.

A further object is to provide a thermostat that can be connected electrically to control both a heating and cooling circuit as desired without the necessity of rearranging the operating parts of the thermostat.

An additional object is to provide a thermostat sub-base having integrally formed supporting elements located so as to support several different arrangements of thermostat components.

In achievement of the objects of the invention a base member of insulating material is provided having a pair of switch positioning bosses, an armature ledge, a spring support abutment, and mounting lugs integrally formed thereon. In one form of the invention, a sleeve member is rotatably received on a post which is secured to the base member. Mounted on the sleeve member is a cam follower which is frictionally restrained against rotation relative to the sleeve member and is biased into engagement with a cam which is rotatably secured to the base member. Connected at its inner end with the sleeve is a spiral bimetal element carrying a movable switch contact for operating an electrical circuit in response to ambient temperature changes. The movable contact carried by the bimetal cooperates with a fixed contact mounted on a bracket member which is located in abutment with one of the switch positioning bosses. For causing snap action of the switch contacts the fixed contact assembly comprises a permanent magnet and a screw contact received in the magnet and supporting bracket which is adjustable to vary the response of the switches to temperature change. Rotation of the cam adjusts the position of the bimetal relative to the fixed contact to increase or decrease the temperature at which the switch contacts will close. For calibrating the bimetal relative to the fixed contact, the cam follower may be selectively rotated against the frictional engagement with the sleeve to adjust the angular position of the bimetal relative to the fixed contact.

In another form of the invention, a permanent magnet is carried by the free end of the bimetal and a magnetically responsive enclosed switch is supported on the switch positioning bosses for controlling either a heating or cooling system in response to the action of the bimetal.

3,190,988 Patented June 22, 1965 A third form of the invention includes a variable heat anticipating resistor rotatably mounted on the base member beneath the post which supports the bimetal. The variable resistor provides a uniform distribution of temperature across the bimetal when the switch contacts are closed, and the base member is mounted on a wall plate having terminals for connection with both a heating and cooling control circuit. a

In a fourth embodiment of the invention a wall plate is provided for the base member with a system switch and a fan switch having terminals for connection with a cooling system and a heating system so that the thermostat can be selectively connected with either circuit to control heating or cooling.

In still another form of the invention, the bimetal element is connected directly with a post which is rotatable relative to the base. A cam follower mounted on the post is frictionally restrained against rotation relative to the post by a spring washer. A novel anti-torque washer cooperates with the variable resistor to prevent changes in resistor settings when the thermostat setting is changed.

Other objects and adavntages of the invention will become apparent from the following description taken in connection with the accompanying drawing in which:

FIG. 1 is a front view of a thermostat embodying one form of the invention;

FIG. 2 is a sectional view of the dial and cover assembly of FIG. 1 with the base member and operating parts of the thermostat indicated in phantom lines; 1

FIG. 3 is a plan view of the base member of the thermostate of FIG. 1;

FIG. 4 is a back view of the base member of FIG. 3;

FIG. 5 is a perspective view of the temperature sensing element;

FIG. 6 is a sectional view taken on line 66 of FIG. 4;

FIG. 7 is a detailed sectional view taken on lines 77 of FIG. 4;

FIG. 8 is a plan view of the base member embodying a second form of the invention;

FIG. 9 is a back view of the base member of FIG. 8;

FIG. 10 is an end view taken on lines 10-10 of FIG. 8;

FIG. 11 is a plan view of the base member embodying a third form of the invention;

FIG. 12 is a back view of the base assembly of FIG. 11;

FIG. 13 is a plan view of a wall plate of the embodiment of FIGS. 11 and 12;

FIG. 14 is a back view of the wall plate of FIG. 13;

FIG. 15 is a detailed sectional view taken on lines 1515 of FIG. 13;

FIG. 16 is a plan view of a thermostat embodying the invention in still another form;

FIG. 17 is a side view, partially in section, of the thermostat of FIG. 16;

FIGS. 18 through 23 are schematic wiring diagrams of the thermostat of FIGS. 16 and 17;

FIG. 24 is a view corresponding to FIG. 3 of the invention embodied in another form;

FIG. 25 is a plan view of the base member of FIG. 24 with a sealed magnetic switch;

FIGS. 26-28 are fragmentary plan views illustrating the assembly of the bimetal post and variable heat anticipating resistor for the embodiment of FIG. 25; and

FIG. 29 is a perspective view of a flexible cutoff lever.

Referring first to the embodiment illustrated in FIGS. 1-7, the thermostat is illustrated generally at 10 in FIG. 1, and includes a cover member 12 in the form of a shell of plastic or other insulating material, a dial 14 rotatably supported on the cover member, and a base member 16 which is frictionally received in the cover member and supports the operating parts of the thermostat. As shown in FIGS. 3 and 4, base member 16, which is also of plastic insulating material, has a front, substantially flat face 18,

3 and a rear face which is depressed to define a peripheral ridge 22.

Formed along the lower edge 17 of base member 16 is a pair of laterally spaced switch positioning bosses 26 which are substantially L shaped in cross section for 10- cating and supporting the thermostat switch on the front face of base member 16. Intermediate the ends of lower edge 17 of base member 16 is an apertured lug 27, the aperture of which receives a rivet for mounting a switch contact support bracket in a manner to be described below. One end of lower edge 17 projects outwardly to define a mounting lug 28 having a recessed slot 29 for receiving a mounting screw 36 for mounting the base member on a wall or other supporting structure. Slot 29 extends through an oblong boss 32 projecting from the rear side of base member 16 (FlG. 4). Formed adjacent the left edge 33 of base member 16 is a recess 34 concentric with a boss 35 on the rear side of the base member (FIG. 4) having a threaded hole for receiving a mounting screw 36. When base member 16 is mounted on a support, slot 29 permits the base member to be adjusted angularly about screw 36 before screw 36 is tightened.

Integrally formed adjacent the right edge 37 of base member 16 is a rectangular armature ledge 38 which projects perpendicularly from front face 18 and serves as a limit stop for a movable armature on the end of the bimetal in one form of the invention, and also serves as a support for an auxiliary armature in another of the invention as will be described presently. Also integrally formed on the base member and spaced inwardly from the corner formed by the upper edge 39 and right edge 37, is a spring support 49 projecting from front face 18 and provided with a notch 41 for receiving the end of a cam follower spring.

Spaced inwardly from edge 33 and formed integrally with the base member is a hub 42 which receives the enlarged end 43 of a post 44. Enlarged end portion 43 is provided with a groove 45 for receiving a washer 46 which in cooperation with a flange 47 formed on post 44, clamps the base member between the flange 47 and washer 46. Post 44 is prevented from rotating relative to the base member by a staking operation.

Rotatably received on post 44 is a sleeve member 418 having an adjusting nut 49 formed at one end which is provided with a circular shoulder 59. Shoulder 54 receives the apertured end of a cam follower 51.

concentrically mounted on sleeve 48 is a second, outer sleeve 52 which is staked to sleeve 48 so that the sleeves rotate as a unit on post 44. The lower end of outer sleeve 52 is spaced from shoulder and a spring washer 53 is mounted between the lower end of sleeve 52 and cam follower 51 to frictionally restrain cam follower 51 against rotation relative to

sleeve members

48 and 52. To compensate for tolerance variations, a spacer washer 54 and a bowed spring washer 55 are received on post 44 between the lower end of adjusting nut 49 and flange 47.

Sleeve members

48 and 52 are maintained in position on post 44 by a washer 56 in cooperation with a cotter pin 57 mounted on the outer end of post 44.

Supported on the outer sleeve 52 is a bimetal element 58 for actuating the thermostat switch in response to temperature variations. Bimetal 58 has its inner end spot-welded to the outer sleeve 52. 'Diametrically disposed relative to hub 42 and post 44 isan elongated rectangular depression 59 for securing a variable heat anticipating resistor to the base member in another form of the invention as will be fully described below. Depression 59 is concentric with a boss 60 formed on the rear face of base member 16.

Formed on rear face 29 of base member 16 is a circular boss 61 (FIG. 7) which is spaced from post 43 toward edge 17. Circular boss 61 is provided with a shoulder 61:: (FIG. 7). Rotatably received in boss 61 is a cam shaft 62 having a shoulder or flange 63 formed intermediate its ends for cooperation with front face 18 of the base member, and a groove 64 is provided adjacent the lower end of shaft 62 for cooperation with an open-sided spring E-washer 65 to secure shaft 42 to the base member. Shaft 62 is chamfered at its upper end and is provided with a fiat 66 for cooperation with the hub of dial 14 for rotating shaft 62 with the dial.

Press fitted onto flange 63 for rotation with shaft 62 is a cam 68 for transmitting the rotation of dial 14 and shaft 62 to cam follower 51. Cam 68 overlies front face 18 of base member 16 and is provided with a tab 69 for cooperation with an arcuate temperature scale 70 formed on front face 18.

Referring to FIG. 5, which illustrates the bimetal and cam follower assembly, cam follower 51 includes a lever arm 71 having a bifurcated end 72, a spring aperture 73, and a cam follower tab 74 bent at right angles to the inner end of lever 71 for engaging the surface of cam 68. For biasing cam follower tab 74 into engagement with the surface of cam 68, a spring 75 (FIG. 3) has one end received in notch 41 of spring support 40, and its other end received in aperture 73 on lever arm 71. Thus, as shaft 62 is rotated, cam 68 acts against cam follower tab 74 to shift cam follower 51 about post 43, and spring washer 53 transmits the rotation to bimetal element 58 through

sleeves

43 and 52. For calibrating the position of camfollower 51 relative to cam 68, a rectangular groove 72a is formed in face 18 for receiving a tool which may be inserted in the bifurcated end portion 72 to hold cam follower 51 stationary while

sleeves

43 and 52 are rotated on post 44.

Bimetal 53 has its free end bent radially outwardly and an armature bar '76 is secured to the free end by a rivet 77 which also secures one end of a spring leaf contact 78 to the armature bar. Armature bar 76 is provided with a slot 79 and a stop tab 80 is bent away from the slot to limit the movement of leaf contact 78 outwardly from armature bar 76.

Referring to FIG. 3, a bracket 82 is mounted on front face 18 for supporting a fixed contact. Bracket 82 is provided with a mounting lug 83 for cooperation with lug 27 and a rectangular mounting tab 84 which is positioned adjacent one of the switch positioning bosses 26. Rivets 85 secure bracket 82 to the base member. Bracket 82 is provided with an upturned flange 86 for supporting a permanent magnet 87. Magnet 87 is formed with a threaded eyelet 88 which is inserted through an opening in flange 86, and a flange 89 formed on eyelet 88 secures the magnet in position on the bracket. Eyelet 88 receives a contact screw 90 having a contact portion 91 for engagement with contact leaf 78 on the bimetal element. Advancing screw contact 9% in eyelet 88 increases the distance from the magnet at which the

contacts

78 and 91 close. This lowers the temperature differential between opening and closing of the contacts since less force is required to separate the contacts as the distance from the magnet to the point of contact is increased. Due to the resiliency of contact leaf 78', a sliding or wiping contact is maintained between fixed contact 91 and leaf contact 78 up to the point of separation. Moreover a sliding contact occurs as the contacts close due to the resiliency of contact leaf 78 minimizing the possibility of arcing caused by rebound as contact is established. As' the bimetal 58 cools, armature bar 76 moves toward permanent magnet 87 until the magnetic attraction overcomes the resiliency of bimetal element 58 and causes the contacts to close with a snap action. Upon heating of bimetal 58, contact is maintained due to the magnetic attraction between magnet 87 and armature bar 76 until the contacts separate with a snap action. Movement of armature bar 76 away from magnet 87 is limited by armature ledge 38.

As shown in FIGS. 4 and 7, a night off control arm 94 is rotatably received on circular boss 61. Control arm 94 has an enlarged apertured end portion 95 which is received on boss 61 and seated against shoulder 61a. End portion 95 is struck away at its peripheral portion to define a tab 96 which extends at right angles to the control arm, and projects through an arcuate slot 97 in the base member into the path of armature bar 76. Control arm 94 may be rotated to a position in which tab 96 prevents closure of the switch contacts to provide a night off control and prevent the heating system from operating when the building or space is unoccupied. Control arm 94 is maintained in position on boss 61 by the cooperation of a retaining screw 98 with an arcuate slot 99 in control arm 94. Screw 98 is mounted in a threaded boss 100 projecting from the rear face 20, and the head of the screw prevents arm 94 from being displaced axially with respect to boss 61, but permits rotation of arm 94 within the extremities defined by slot 99.

Formed on ridge 22 adjacent the lower edge 17 of the base member (FIG. 4) is a raised rectangular boss 101 which cooperates with a bead 102 formed in control arm 94 to maintain the setting of control arm 94 at the extremities of its arcuate movement due to the resiliency of the material of control arm 94. The resilient engagement of bead 102 with boss 101 also serves to maintain the intermediate settings of control arm 94.

Illustrated diagrammatically in FIG. 3 is a fixed resistor 105 of conventional construction which is positioned adjacent to bimetal 58 and is secured to the base member by a screw 104. Resistor 105 is provided with a connector 103 and is connected in series with bracket '82 by a conductor 106 to serve as a heat anticipator when the switch is closed to prevent overshooting of the furnace controlled by the thermostat due to the time lag between ambient temperature rise and furnace operation.

Mounted on the rear face 20 (FIG. 4) are two

terminal screws

107 and 108 having

terminal clips

109 and 110, respectively, for connecting the thermostat with the lead wires from an electrically operated valve or the like which controls the furnace. Screw 104 serves to secure a terminal clip 111 to the rear face of the base member which is electrically connected by a conductor 112 to terminal clip 110. Terminal clip 109 is connected by a conductor 113 with bimetal 58, conductor 113 passing through an opening beneath notch 41 in spring support 40 and is soldered or welded to sleeve member 52. The conductors and terminal clips are all properly insulated and the conductors are connected by a combination of mechanical pressure and soldering.

FIGS. 1 and 2 illustrate the cover and dial assembly of the thermostat in which cover member 12 is provided with a circular boss 114 having a shoulder 115. Rotatably received in the opening of boss 114 is the hub 116 of dial 14, and a spring washer 117 engages the inner end of the hub and the periphery of the opening to resiliently maintain dial 14 in place on the cover. Spring washer 117 rotates with hub 116. Hub 116 is provided with a cylindrical opening having a fiat wall which cooperates with the flat portion 66 of cam shaft 62. Cover member 12 is provided with an arcuate groove 119 which cooperates with tab projection 120 at the periphery of dial 14 to provide stops at maximum and minimum settings within the operating range of the thermostat.

Adhesively attached to the front of cover member 12 is a foil scale plate 121 having appropriately spaced temperature markings which are visible through the transparent dial 14. Dial 14 is provided with a raised convex portion 122 to magnify the temperature markings for better visibility. Convex portion 122 is provided with a temperature indicating mark 123 for cooperating with the temperature markings on the front of the cover member. Concentrically mounted on boss 114 is a second spiral bimetal 124 having its inner end secured to the boss and having a pointer 125 formed on its free end to indicate the ambient temperature.

Cover member 12 receives base member 16 through its open back with notches 126 cooperating with projections 127 (FIG. 3) to maintain a pressfit engagement between the cover and base member. Rectangular openings 18 in the side walls of the cover member permit free flow of ambient air beneath the cover for bimetal 58, and also to provide an opening through which control arm 94 extends from the cover to be accessible for manual operation. Rotation of dial 14 acts through cam shaft 62 to increase or decrease the temperature at which

contacts

70 and 91 will close. Base member 16 (FIG. 3) is provided with an arcuate slot 130 beneath the tab 69 of cam 63 into which may be inserted adjustable stop screws 132 (FIG. 11) to provide maximum and minimum temperature settings for cam 68. The temperature indicating marks of scale 70 correspond to the positions of cam 68 and dial 14.

To calibrate the thermostat, it is placed in a controlled temperature within the operating range of the thermostat. Tab 69 of cam 68 is positioned at the indicating mark on scale 70 corresponding to the controlled temperature. A screw driver blade is then inserted into the bifurcated end 72 of cam follower lever 71 and the cam follower is maintained stationary by engagement of the screw driver blade with notch 72a.

Sleeves

48 and 52 are then rotated on post 44 against the frictional resistance of spring washer 51 to move bimetal 58 to a position such that

switch contacts

91 and 78 just close at the controlled temperature.

Clockwise rotation of cam 63 acts through cam follower 51 to cause clockwise rotation of bimetal 58 on post 44 (as viewed in FIG. 3). This causes armature bar 76 to move further away from contact 91 requiring a lower temperature to actuate the switch. As the ambient temperature decreases, bimetal 58 deflects to move armature bar 76 and spring leaf contact 78 toward the magnet until the force of magnetic attraction overcomes the resiliency of bimetal 58 and causes the contacts to close with a snap action. Cam 68 is designed so that the amount of bimetal deflection per degree of temperature change corresponds to the angular rotation of shaft 62 and cam 68 between the different temperature settings on

scales

121 and 70. Thus, the temperature indicated at 123 is the temperature at which the contacts will close.

When

contacts

78 and 91 close, the current path is as follows: from terminal 107 through conductor 113 to bimetal 58, from bimetal 58 through

contacts

78 and 91 to bracket 82, from bracket 82 through conductor 106 to the heat anticipation resistor 105, and from resistor through screw 104, terminal clip 111 and conductor 112 to terminal clip 110.

Resistor 105 is heated when energized by the switch to increase the temperature at the bimetal to cause the switch contacts to separate slightly before the ambient temperature reaches the temperature setting so that the ambient temperature will not increase above the temperature setting due to the lag between the ambient temperature rise and furnace operation.

In a typical installation, base member 16 is mounted on the wall of the room or space to be heated by means of

screws

30 and 36 and an electrically operated gas valve is connected in series with

terminals

107 and 108 of the thermostat. When the thermostat is set to provide a temperature above the ambient air temperature, the bimetal defiects to close the

switch contacts

78 and 91 to complete the circuit, and the gas valve is actuated to start the furnace into operation. Current flows from bracket 82 to resistor 105 which generates heat adjacent to the bimetal in addition to the ambient air temperature to compensate for the lag in ambient air temperature as sensed by the thermostat so as to avoid over-shooting the temperature setting. When the required temperature increase results in an attained temperature at the bimetal equal to the setting temperature plus the temperature difierential (approximately 2 degrees to 3 degrees Fahrenheit) of the switch as controlled by the setting of contact 91, the switch contacts open due to the heating of bimetal 58, shutting off the gas valve to the furnace. Opening of the switch contacts also deenergizes the anticipator resistor 105 as it is in series with the switch. Upon subsequent cooling of the bimetal, the switch contacts close when the set temperature is reached and the operating cycle is repeated.

Illustrated in FIGS. 8, 9, and 10 is a second embodiment of the invention in which the base member supports a different arrangement of components. Identical structure to that of the first embodiment is identified in FIGS. 8-10 by the same reference numerals.

In the embodiment illustrated in FIGS. 8-10, bimetal element 58 carries at its free end a permanent magnet 200. Slidably mounted on armature ledge 38 is a U- shaped auxiliary armature clip 202 (FIG. 10) to provide an adjustable temperature differential. Auxiliary armature 202 is adjusted laterally on ledge 38 to provide the desired temperature differential, after which it is sealed in place by resinous sealing material.

Mounted on the L-shaped switch positioning bosses 26 is a glass enclosed magnetically responsive switch 204. Switch 204 is of the type disclosed in the copending application of John C. Hewitt, In, Serial No. 54,620, filed September 8, 1960, now patent No. 3,068,333, granted on December 11, 1962, and assigned to the assignee of this invention. Switch 204 is a glass enclosed, but unsealed version of the switch disclosed in the above referred-to copending application, and is provided with a non-magnetic dust cap 206 which is press-fitted over the open end of the switch 204. For securing switch 204 on base member 16, a hooked spring clip 208 is mounted in a slot 209 in the base member, and switch 204 is received in the hooked portion of the spring clip and resiliently maintained in position on bosses 26.

As is fully disclosed in the above referred to copending application, switch 204 is provided with a pair of fixed contacts which are connected with terminals of separate circuits, and a movable contact connected with a terminal common to both of the circuits. The movable contact is spring-biased into engagement with one of the fixed contacts and is actuated in response to magnetic flux to snap closed against the other contact. In the thermostat of FIG. 8, the movable contact of switch 204 is biased against a fixed contact which is connected with a cooling conductor 212. Cooling conductor 212 is not connected to a control circuit since the thermostat is illustrated in FIG. 8 as a heating control only. Switch 204 has its other fixed contact connected to a heating conductor 210 for controlling a heating system, and the movable contact is connected to a power conductor 214 which is to be connected to a power source.

When bimetal 58 is heated, it deflects to move magnet 200 into engagement with auxiliary armature 202 and the movable contact of switch 204 moves to the cooling position, but since conductor 212 is disconnected, no current can flow to the thermostat. This is the heating off position of switch 204.

When bimetal 58 cools, magnet 200 is moved adjacent switch 204 causing the movable contact to snap to the heating on position connecting power conductor 214 with heating conductor 210. With

terminal screws

107 and 108 connected in series with a furnace control, a current path is provided from terminal clip 109 (FIG. 9) through conductor 214 to switch 204, from switch 204 through conductor 210 to heat anticipating resistor 105 and terminal clip 111, and from terminal clip 111 through conductor 112 to terminal clip 1110. Except for the use of the glass enclosed switch 204 and auxiliary components just described, the operation, calibration and glass housing which is gas filled. Switch 304- is connected with a heating conductor 310 and a cooling conductor 312 with the movable contact connected to a power conductor 314.

Mounted on post 43 beneath sleeve 48 is a variable heat anticipating resistor 316. Resistor 316 is of the type disclosed in the copending application of John C. dewitt, Jr., Serial No. 148,283, filed October 27, 1961, now Patent No. 3,147,354, granted on September 1, 1964, and assigned to the assignee of this invention. The latter Hewitt application discloses a resistance coil holder rotatably mounted for cooperation with a pair of fixed, congruent contact wipers for varying the resistance between the contact wipers upon rotation of the coil holder. An elongated leaf spring biases the coil holder into engagement with the contact wipers. Another embodiment disclosed in the same application concerns a fixed coil mounted in a base member for cooperation with a rotatable wiper blade having contact surfaces for cooperating with the resistance coil to vary the number of coils between the contact surfaces when the wiper blade is rotated relative to the resistance coil. In FIG. 11, an arm 318 is connected withthe movable element of the variable resistor and cooperates with an arcuate scale 320 formed on the base member 16 which provides amperage markings by which the resistor settings corresponding to switch loading can be made.

The embodiment of FIGS. 11 and 12 is adapted for use as both a heating and cooling control and the control arm 94 has been omitted. However, control arm 94 may be included when the thermostat is operating to control a heating system.

In the embodiment of FIGS. 11 and 12, base member 16 is mounted on a wall plate 322 illustrated in FIGS. 13, 14, and 15. Wall plate 322 is provided with a substantially fiat front face 323 and a back face 324 (FIG. 14) which is recessed to define a peripheral ridge 32.5. Mounted on the front face 323 of wall plate 322 are three stepped

terminal connectors

326, 327' and 328. As shown in FIG. 15, terminal connector 328 is seated on a stepped boss 329 having

openings

330 and 331 for receiving

cylindrical projections

332 and 333 which are provided with internally threaded holes334 and 335, respectively. Cylindrical projection 332 extends from an upper portion 328a and cylindrical projection 333 extends from a lower portion 328b. Portions 328a and 32812 are connected by a vertical portion 328a. Mounted in the threaded hole 335 is a terminal screw 336 which secures a terminal clip 337 to the connector 328 for electrical connection with the lead wire from a cooling relay.

Connector 328 is secured to wall plate 322 by bentover tabs 338 which cooperate with an opening 339 and a notch 340 in the wall plate, the tabs being received in a recess 341 formed on the back face of the wall plate.

Connectors

326 and 327 are identical in construction to connector 328 and are provided with

terminal screws

342 and 343, respectively, and threaded

holes

344 and 345, respectively, for receiving contact screws from base member 16 in a manner to be described below.

Pormed on the back face 324 of wall plate 322 is a cylindrical boss 345 which is concentric with a cylindrical depression 347 on the front face 323 for receiving hub 42 and the end of post 44 when base member 16 is secured to the wall plate. An opening 348 is provided in the wall plate for access to the wires from the wall which are to be connected to

terminals

326, 327 and 328.

Semi-circular grooves

349 and 350 are formed on the side edges of'wall plate 322 for accommodating

bosses

35 and 32, respectively, of base member 16. Provided on the back face 324 is a boss 351 having a slotted recessed opening 352 which receives a mounting screw 353 for securing wall plate 322 to a wall. A second mounting boss 354 is provided adjacent the opposite corner of the wall plate for receiving a mounting screw 355.

Again referring to FIG. 12, two

terminal clips

359 and 360 are secured to

bosses

361 and 362, respectively, by

rivets

363 and 364.

Terminal clips

359 and 360 are provided with apertured cup-shaped portions which are positioned over the holes in

bosses

361 and 362, and

captive screws

365 and 366 are mounted in the cup-shaped portions, with the screw heads being received in the recessed openings on the front face of base member 16 (FIG. 11).

Screws

365 and 366 are threadedly received, respectively, in

holes

345 and 344 of

terminal connectors

327 and 326 when the base member is secured to wall plate 322.

Terminal clips

367 and 368 are riveted, respectively, to bosses 369 and 370 (FFIG. 12) formed on the rear face 20 of base member 16.

Screws

371 and 372 are threadedly mounted in

terminal clips

367 and 368, respectively. When base member 16 is mounted on wall plate 322, screw 371 is received in threaded hole 346 of terminal connector 328, and screw 372 is received in a threaded boss 373 formed on the front face 323 of wall plate 322.

Conductor 314 from switch 304 passes through an opening inbase member 16 and isconnected with terminal clip 359 ('FIG. 12). Cooling conductor 312 from switch 304 extends through the same open-ing and is connected with terminal clip 367. Heating conductor 310 from switch 304 extends through an opening in base member 16 and connects with one end of the resistace coil of the variable heat anticipating resistor 316. The other end of the coil of heat anticipating resistor 316 is connected by a conductor 374 with terminal clip 360. Terminal screw 342 (FIG. 13) electrically connects one end of the lead wire from an electrically operated gas valve through opening 348 to connector 326. Terminal connector 327 is connected with the lead wire from the main power source by terminal screw 343, and connector 328 is connected with the lead wire from an electrically operated relay for the cooling circuit by means of terminal screw 336. For selecting the circuits for heating operation, cooling operation, or complete off, an additional three-way switch ahead of the wall plate can be used.

As a heating thermostat, bimetal 53 deflects, upon cooling, to move the permanent magnet 200 toward switch 304 until its movable contact electrically connects

conductors

310 and 314 to start .the furnace into operation. The current path is as follows: the main power source is connected with terminal 343 and current flows from terminal 343 through connector 327 and screw 365 to power conductor 3114, and through conductor 314 into switch 304 to heating conductor 310, from heating conductor 3110 through resistor 316 to conductor 374, and from conductor 374 through screw 366 to connector 326 and terminal screw 342.

As a cooling thermostat,and assuming that the threeway switch is in the on position with respect to the cooling side of the three-way switch, the movable contact of switch 304 electrically connects cooling conductor 312 with power conductor 314 when permanent magnet 200 is moved away from switch 304 due to heating of the bimetal 58. The current path is as follows: from terminal screw 343 through connector 327 and screw 365 to power conductor 314, through cooling conductor 312 to terminal clip 367, from terminal clip 367 through screw 371 to connector 328, from connector 328 to terminal screw 336 which is connected with the lead wire from the cooling circuit. Heat anticipating resistor 316 is inoperative when the thermostat operates as a cooling thermostat.

FIGS. 16 and 17 illustrate a fourth embodiment of the thermostat in which the base assembly of FIGS. 11 and 12 is combined with a cover member 400 and is mounted on a wall plate 401. Rotatably mounted on cover member 400 is a dial 402 which contains the same functional components as those described for the cover and dial assembly shown in FIGS. 1 and 2. Cover member 400 is provided on its front face with a foil scale plate 403 with switch position indicating markings as illustrated.

Screws

372, 37 1, 365 and 366 (FIG. 11) are received in threaded bosses on wall plate 401 for mounting base member 16 upon the 'wall plate. For assisting in positioning base member .16 on wall plate 401, a plurality of raised positioning bosses are formed on the wall plate, one such boss being illustrated at 4M (FIG. 17).

Wall plate 461 is provided with a bracket (not shown) for mounting a double pole, triple throw, system control switch 405 and a single pole, double throw, fan control switch 406 which are illustrated schematically in FIGS. 18-23. Slide actuators 40 7 and 408 are provided respectively for

switches

405 and 406, and project through an appropriate opening in cover member 400 as shown in FIG. 16. Dial 403 contains indicating markings heat, off and cooling for the three positions of the control switch 405, and markings man (manual) and auto (automatic) for the two positions of fan control switch Control switch 405 is provided with

terminals

409, 410, 411, 412, 413, 414, 415, and 416, and fan control switch 406 is provided with

terminals

417, 418, and 419. Terminals 41 1, 413, and 4 15 of control switch 405 are connected by a shunt wire 420 with terminal 417 of fan control switch 406. Terminal 411 of switch 405 is connected by a conductor 422 to a power terminal 423 on wall plate 401 which in turn is connected through an opening in wall plate 401 with a lead wire 424 from one side of the secondary of a transformer 425. Terminal 414 of control switch 405 is connected to terminal 419 of fan switch 436 by a conductor 446.

Wall plate 40.1 is provided with

terminal connectors

426, 427 and 428 which are identical in construction and correspond, respectively, to

terminal connectors

326, 327, and 328 of wall plate 322 illustrated in FIG. 13. Connected in series between

terminals

427 and 428 is a fixed, cooling system heat anticipating resistor 421.

Terminal connectors

426, 427 and 428 are seated on raised bosses as in the previously described embodiment of FIG. 13, one such boss 429 for terminal connector 428 being illustrated in FIG. '17.

Screws

366, 365, and 371 (FIG. 11) of base member 16 are threadedly received in

connectors

426, 427 and 423 respectively, to electrically and mechanically connect the terminal connectors with the base member. Connector 427 is connected to power terminal 423 by a conductor 43 1.

FIGS. 18-23 illustrate the operation of the thermostat of FIGS. 16 and 17 in a typical installation. Wall plate 401 is provided with a heating terminal 433, a fan terminal 434, and a cooling terminal 435. Through an opening in wall plate 401, heating terminal 433 is connected with a lead wire conductor 439 from a conventional control 443 such as a relay fora volt system, of a heatingcontrol circuit. Relay 440 controls a circuit which includes an electrically actuated fuel control valve or the like so that when relay 440 is on, that is, when it is energized electrically by the thermostat, the valve opens to start the furnace into operation.

Fan terminal 434 is connected through an opening in wall plate 401 with a lead wire conduct-or 442 from a fan circuit relay 443. Energization of relay 443 supplies power to a cooling fan which is normally provided with a separate on-olf switch in the circuit so that the fan can be turned on or olf regardless of the thermostat setting. In a typical system a separate fan control circuit would be provided to operate a heating fan in response to air duct temperature.

Cooling terminal 435 is connected with a lead wire conductor 444 from a cooling circuit relay 445. Energization of relay 445 completes a cooling system control circuit to bring the cooling system into operation.

The movable contact of switch 308 is illustrated diagrammatically at 308a in FIGS. l8-23. In FIGS. l8, l9 and 20, switch .303 is shown in the heating on position due to the thermostatic actuation of the switch by bimetal 58 and magnet 200. In FIGS. 18, 19 and 20, bimetal 58 is cooled, causing magnet 200 to move toward switch 308 and actuate contact 303a to the heating position. Thus,

11 the thermostat is demanding heat in FIGS. l8, l9 and 20.

In FIGS. 21, 22 and 23, switch 398 is in the cooling on position with contact Eitiiia electrically connecting power conductor 314 with cooling conduct-or 312. Contact 3178a snaps to the cooling position when magnet 2% is attracted to auxiliary armature 2&2 upon heating of bimetal 58.

In FIG. 18, control switch 405 is the heat position and fan switch 4% is in the manual position. With switch 3&8 in the heating position, a circuit is completed to relay 44% to bring the furnace into operation. The circuit extends from the secondary of transformer 4-25 through

conductors

424, 431 and 314 to switch 3%; from switch 363 through conductor 31%, the variable heat anticipating resistor 314i and conductor 43%? to terminal 412 of control switch 465; and from terminal 412 through actuator 4-97, terminal 414?, and conductors and 439 to heating relay 440; and from relay i t-t3 and conductor 441 to the other side of the transformer secondary. When contact Stlfia moves to the cooling position upon satisfaction of the thermostat, the circuit is broken to the heating relay to shut down the furnace.

'In either position of switch 3%, a fan circuit is completed since actuator 4%, when in the manual position, connects terminal 418 with terminal 417, which in turn is connected with shunt wire 426 to provide a circuit from the transformer secondary through

conductor

424, and 422 and shunt wire 42% to terminal 417; from terminal 417 through actuator 4% to terminal 418; from terminal 418 through

conductors

437 and 442, relay 443 and conductor 4 51 to the other side of the transformer secondary. Accordingly, the fan may be controlled by its on-off switch independently of the thermostatically actuated switch 3%. Cooling relay 4 .5 is off in either position of switch 3% with control switch 465 in the heating position and fan switch 4% in the manual position.

With fan switch 406 in the auto position and control switch 4% in the heat position as shown in FIG. 19, the operation of heating relay 44% is the same as in FIG. 18, but fan relay 443 and cooling relay 445 are both off in either position or" switch 3%.

In FIG. 20, control switch 495 is in the off position and fan switch 4416 is in the manual position. Heating relay 449 and cooling relay 445 are both off in either position of thermostat switch 368, and the fan relay 443 is on in either position of thermostat switch 393 as in the FIG. 18 condition to permit fan operation for cooling without operation of the cooling system controlled by relay 445.

PEG. 21 illustrates the control switch 405 in the off position and fan switch 466 in the automatic position with the result that heating relay 440, fan relay 443 and cooling relay 445 are all oif in either position of switch 303.

Control switch 4175 is in the cooling position in FIG. 22 and fan switch 4% is in the manual position. When switch 308 is in the cooling position, a cooling circuit extends from the transformer secondary through

conductors

424, 451 and 314 to contact 3%:1 of the thermostat switch; from switch 3% through

conductors

312 and 432 to terminal 414 of control switch 465; from terminal 414 through actuator 4637 to terminal 416 and through

conductors

446, 438 and 444 to cooling relay 445, and from relay 445 through conductor 441 to the other side of the transformer secondary. When switch Silt: moves to the heating position, the cooling relay is ofi. Fan relay 443 is on continuously in either position of switch 308. The current bypasses fixed heat anticipating resistor 421 due to its high resistance. Resistor 421 is therefore oil", or tie-energized at all times when fan switch 4% is in the manual position. Heating relay 440 is off in either position of switch 563 when control switch 4&5 is in the cooling position.

FIG. 23 illustrates the same condition for control switch 12 46 5, but fan switch 4% is in the automatic position to connect fan relay 443 in parallel with cooling relay 445. When switch 3i8is in the cooling position, a current path is provided from the secondary of transformer :25 through

conductors

424, 431 and 314, switch 3%,

conductors

312 and 432, actuator 407 and conductor 446 to terminal 419 of fan switch 4%, and from terminal 419 through

parallel conductors

437 and 433 to the fan relay 443 and cooling relay 445, respectively, to conductor 441 and the other side of the transformer secondary. An alternate current path is provided through fixed resistor 421, but due to the high resistance of resistor 421, it receives only a minimum amount of current and is effectively shunted outwhen switch 3% is in the cooling position.

When switch 398 moves to the heating position in the condition illustratedin FIG. 23, fan relay 443 and cooling relay 445 are in series with fixed resistor 421, and a circuit extends fromthe transformer secondary through

conductors

424 and 431, resistor 421, conductor .432, actuator 487, conductor 446 and through the parallel conductors to the fan relay 443 and cooling relay 445 to the other side of the transformer secondary. However, the high resistance of resistor 421 prevents sufficient current to flow to the fan and cooling relays, and since resistor 421 receives the full current load, it generates heat for bimetal 58 to operate as a cooling system heat anticipator. Thus, as the ambient temperature approaches the set temperature of the thermostat, the heat generated by resistor 421 causes bimetal 58 to deflect to move magnet 2% against auxiliary armature 292 and snapactuate 308a to the cooling position before the ambient temperature reaches the set point. This prevents the temperature from rising above the set point due t the lag in the cooling efiect of the cooling system after the thermostat switch closes.

F163. 24 and 25 illustrate another form of the invention employing respectively an open contact switch and a sealed magnetic switch.

Rotatably mounted on the base member 16' (FIG. 24) is a post 44 having a screwdriver slot 44a at its upper end. A spring washer 53' is staked against cam follower 51 to frictionally restrain the cam follower against rotation relativeto post 44. Cam follower 51 is biased into engagement with cam 68' by spring 75 connected between the end of lever arm 71 and a spring support 41%.

Projecting from the front face of the base member 16 in the path of lever arm 71' is a stop post 5%. In order to lower the calibration, post 44 may be rotated counter clockwise by engaging slot 44a with a screwdriver. Lever arm 71' will strike stop post 5% and continued counter clockwise rotation will cause slippage between the post and cam follower to lower the calibration.

To raise the calibration, post 4-4 is rotated clockwise and cam follower 51 is held stationary against cam 68' or a tool positioned in the path of lever arm 71, so that the resulting slippage will increase the calibration. In FIG. 24, the switch contacts 78 and 91' are enclosed m a housing5ti2 of transparent plastic material. Magnet 87 is mounted on a bracket 22 with fixed contact 91' provided with a screwdriver slot for adjustment, and a locking nut 91a. Cam differs from cam 68 previously described in that an indentation is provided in tab 69 to resiliently engage the temperature scale To ensure snap opening of the switch contacts upon satisfaction of the thermostat, and to break contact between the movable contact and magnetic field of magnet 87, a cut-off lever SM is mounted on the rear face of base member 16'. Cut-off lever 5% is shown in detail in FIG. 29 and comprises an enlarged apertured lug portion 5536 for securing the lever to the rear face of the base member. Projecting at substantially a right angle from lug portion 536 is a resilient arm member 5%. Arm member 5% extends through slot 97'. For the open contact switch of the shape.

type illustrated in FIG. 24 an extension 510 projects from the end of arm member 508 and engages armature bar 76 at the free end of the bimetal. When the switch contacts are closed as. illustrated in FIG. 24, arm member 508 exerts a biasing force on the movable contact tending to separate the contacts. As soon as the set point temperature is reached to satisfy the thermostat, the resilient force of arm member 508 augments the force of bimetal 58 as it urges the contacts apart and the contacts are opened with a snap action.

In the version of FIG. 24, a fixed heat anticipating resistor may be provided with a connector 103 secured to the base member and having an enlarged apertured end portion received on post 44'.

In FIG. 25, the sealed magnetic switch 304 with the movable contact 398a is mounted on bosses 26' of base member 16 by a spring clip 208. Mounted on the end of switch 304 is a sleeve 512 of resilient material to eliminate noise produced by the snap engagement of magnet 200 with the switch housing. Instead of auxiliary armature 202 on ledge'38, the free end of the bimetal which carried magnet 200 is provided with an extension 514 having a bent tab 516 which cooperates with a stationary armature 518. Tab 516 may be bent in either direction to vary the spacing and thus the temperature differential. To eliminate the noise of tab 516 striking armature 51S, tab 516 is provided with sleeving 520. Arm member 508 of cut-off lever 504 urges the magnet 200 away from the switch housing. However due to the change in spacing, extension 510 of cut-off lever 504 is omitted from the FIG. 25 embodiment as indicated by the broken lines of FIG. 29. As cam 68 is rotated counter clockwise toward the off position, arm member 508 pushes the magnet away from the switch and the cam follower may be locked in a notch 68a formed on cam 68.

FIGS. 26, 27 and 28 illustrate the assembly of variable resistor 316, previously described with reference to the embodiment of FIG. 11, on base member 16'. Fixedly mounted on base 16 on diametrically opposite sides of aperture 44a, is a pair of helically Wound coils 316a and 316b, as clearly disclosed in the latter referred to Hewitt application. Post 44' is mounted in aperture 44a and a contact wiper blade 317 is received on post 44 (FIG. 27) having oppositely disposed crests defining wiper contacts 317a and 317b, which engage respectively the oppositely disposed resistance coils 316a and 31Gb. As clearly disclosed-in the latter referred to Hewitt application, rotation of wiper contact 317 about post 44- varies the number of coils of resistors 316a and 3161; which are in contact with contacts 317a and 317b of the wiper contact.

In order to prevent undesired rotation of the rotatable contact 317 upon rotation of cam 68 or upon calibration of cam follower 51' with respect to cam 58', an anti-torque washer 524 is mounted on post 44' having an enlarged centrally apertured concave portion 526, the outer rim 528 of which resiliently engages the rotatable wiper contact 317. Extending radially from enlarged portion 526 is a locking leg 530 having a recess 532 at its end for engaging stop post 500. Formed on post 44 is an enlarged shoulder 49 which is illustrated in FIG. 24 as being hexagonal in However, the hexagonal configuration is not necessary due to the provision of slot 44a.

Shoulder 49' overlies concave portion 526 of 524 and resiliently biases the concave portion against contact 317 and restrains contact 317 against rotation relative to post 44. Accordingly, if it is desired to change the setting of resistor 316, arm 318 can be rotated about post 44 against the frictional engagement of washer 524. However this calibration of the thermostat by rotating post 44' and cam 51 relative to cam 68, can be accomplished without effecting the setting of resistor 316.

While specific examples of the invention have been illustrated and described, it will be understood that the invention is not limited to the exact construction illustrated, and that various alterations and modifications in the construction and arrangement of parts are possible within the scope of the invention as defined by appended claims.

What is' claimed is:

1. A control device comprising;

a base member of insulating material,

electrical switch contacts on the base member,

a post rigidly secured to the base member,

an inner sleeve member rotatably received on the post having an enlarged adjustment nut formed at its lower end adjacent the base member,

a circular shoulder formed on the adjustment nut,

a cam follower received on the circular shoulder,

an outer sleeve member concentrically mounted on the inner sleeve member and fixed against rotation relative to the sleeve member,

the lower end of the outer sleeve member being spaced from the circular shoulder,

a resilient spring washer mounted on the inner sleeve member between the cam follower and the lower end of the outer sleeve member for frictionally restraining the cam follower against rotation relative to the sleeve members, 1

a bimetal element secured at one end to the outer sleeve member with its other end movable in response to ambient temperature variations for operating the switch contacts,

and a cam rotatably mounted on the base member operatively engaging the cam follower for varying the temperature response of the bimetal member,

said cam follower and sleeve members being selectively rotatable relative to each other for calibrating the position of the bimetal relative to the cam.

2. A control device comprising:

a base member having a front face and a rear face,

a circular, apertured boss projecting perpendicularly from the rear face,

a shaft rotatably mounted in the aperture of the boss .and extending perpendicularly from the front face,

a cam mounted on the shaft and overlying the front face,

a post rigidly secured to the base member and extending perpendicularly from the front face,

an innersleeve rotatably mounted on the post with an enlarged adjustment element formed thereon,

a cam follower mounted on the inner sleeve against the adjustment element and biased into operative engagement with said cam,

an outer sleeve concentrically mounted on the inner sleeve and fixed against rotation relative to the inner sleeve,

the outer sleeve having one end spaced from the enlarged adjustment element,

a spring washer concentrically received on the inner sleeve between the cam follower and said one end of the outer sleeve to frictionally restrain the cam follower against undesired rotation relative to the sleeve members,

a fixed contact on the front face of the base member,

a bimetal element secured at one end to the outer sleeve,

a movable contact carried by. the free end of the bimetal element for engagement with the fixed contact in response to ambient temperature changes,

a control arm rotatably mounted on the circular boss and overlying the rear face of the base member,

a slot in the base member,

and a stop tab on the control arm projecting through the slot into the path of movement of the movable contact for selectively engaging the movable contact upon rotation of the control arm to prevent actuation of the fixed and movable contacts.

3. A control device as defined in claim 2 including: an arcuate slot in the control arm radially spaced from the circular boss, anda retaining screw having a stem extending through 1 5 the arcuate slot and threadedly connected with the rear face of the base member,

the head of the retaining screw cooperating with said arcuate slot to prevent axial displacement of the control arm relative to the base member.

4. A control device as defined in claim 2 including:

a heat anticipating resistor mounted on the front face adjacent the bimetal element,

first and second terminals on the rear face of the base member for connection with a heating control,

a third terminal on the rear face in electrical engagement with the heat anticipating resistor,

a conductor connecting the fixed contact with the heat anticipating resistor,

a conductor connecting the second and third terminals,

and a conductor connecting the bimetal element to the first terminal.

5. A control device comprising:

a base member of insulating material having a front face and a rear face, a

a post rigidly secured to the base member and projecting perpendicularly from the front face,

:an inner sleeve member rotatably received on the post having an enlarged adjustment nut formed at its lower end adjacent the base member,

a circular shoulder formed on the adjustment nut, a cam follower received on the circular shoulder,

an outer sleeve member concentrically mounted on the inner sleeve member and fixed against rotation relative to the inner sleeve member,

the lower end .of the outer sleeve member being spaced from the circular shoulder,

a resilient spring washer mounted on the inner sleeve member between the cam follower and the lower end of the outer sleeve member for frictionally restraining the cam follower against rotation relative to the sleeve members,

an apertured boss projecting from the rear face of the base member,

a shaft rotatably mounted in the aperture of the boss and extending perpendicularly from the front face,

a cam mounted on the shaft and overlying the front face, 7

a spring support on the front face of the base member,

a lever arm formed on the cam follower,

a spring having one end connected to the spring support and the other end connected to the lever arm biasing the cam follower into engagement with the cam,

electrical switch means mounted on the front face of the base member,

a ledge projecting perpendicularly from the front face,

and a bimetal element secured at one end to the outer sleeve,

the free end of the bimetal element being movable between the switch means and the ledgefor operating the switch means in response to ambient temperature variations.

6. A control device as defined in claim 5 including:

a control arm rotatably mounted on theapertured boss and overlying the rear face of the base member,

a slot in the base member, a Y

and a stop tab on the control arm projecting through the slot into the path of movement of the freeend of the bimetal for selectively engaging the free end of the bimetal to prevent actuation of the switch means.

7. A control device comprising:

a base member of insulating material,

a switch mounted on the base member including,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contact and magnetically responsive to engage the second fixed contact,

a cam rotatably mounted on the base member,

iii 1 a post rigidly secured to the base member,

a sleeve rotatably mounted on the post,

a cam follower mounted on the sleeve and biased into engagement with the cam,

an auxiliary armature member on the base member displaced from the switch,

a spiral bimetal element secured :at one end to the sleeve and disposed in a plane parallel to the base,

and a magnet carried by the free end of the bimetal element for movement between the switch and the auxiliary armature in response to ambient temperature variations to actuate the movable contact of the switch between the first and second fixed contacts.

8. A control device as defined in claim 5;

said switch means comprising,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contact and operative in response to magnetic attraction to engage the second fixed contact, a

a magnet carried by the free end of the bimetal for alternately connecting the movable contact with said first and second fixed contacts in response to ambient temperature variations,

and an auxiliary armature member mounted on said ledge.

9. A control device as defined in claim 7 including;

a resistor on the base member electrically connected in series with the second fixed contact of the switch for heating the bimetal element upon closure of the movable contact with the second contact.

10. A control device as defined in claim 9;

said resistor including,

an element having an elongate resistance coil winding,

and an element having arcuately formed contact wipers rotatably relative to the winding for variably engaging equal and oppositely disposed portions of the winding,

said winding being disposed in the plane of the base member with equal portions of the winding on opposite sides of said post,

one of said elements being rotatably mounted on said post independently of the sleeve,

and the other of said elements being secured to the base member and electrically connected in series with the second fixed contact of the switch.

11. A control device as defined in claim 10 including;

an indicating tab on the cam,

an arcuate slot in the base member in the plane parallel to the path of rotation of the indicating tab,

and adjustable stop screws in the arcuate slot for selectively limiting the angular rotation of said cam.

12. A control device comprising;

a base member of insulating material having a front face and a rear face,

a switch mounted in the front face including,

first and second fixed contacts,

a cam rotatably mounted on the front face,

a post secured to the base member and projecting perpendicularly from the front face,

a sleeve rotatably mounted on the post, a

a cam follower mounted on the sleeve and biased into engagement with the cam,

an auxiliary armature member on the base member displaced from the switch,

a spiral bimetal element secured at one end to the sleeve and disposed in a plan parallel to the base,

a magnet carried by the free end of the bimetal element for movement between the switch and the auxiliary armature in response to ambient temperature variations to actuate the movable contact of the switch between the first and second fixed contacts,

a resistor on the base member electrically connected in series with the second fixed contact of the switch for heating the bimetal element upon closure of the movable contact with the second contact,

a plurality of bosses projecting from the rear face of the base member,

an opening in the base member through each of said bosses,

a resilient terminal clip of conductive material secured to each of said bosses,

each of said terminal clips having an apertured cup-shaped portion overlying the opening of the boss to which it is secured,

and a screw of conductive material threadedly mounted in the aperture of the cup-shaped portion of each of said terminal clips.

13. A control device as defined in claim 12 including;

a wall plate of insulating material secured to the rear face of the base member and having a front face and a rear face,

a plurality of stepped terminal connectors of conductive material mounted on the front face of the wall plate,

each of said terminal connectors comprising,

upper and lower horizontal portions connected by a vertical portion,

a threaded opening in each of said upper and lower portions,

the threaded opening in said upper portion of each of said connectors being axially aligned with one of the apertured cup-shaped portions of one of said terminal clips,

and the screw mounted in said one cup-shaped portion threadedly received in said threaded opening of the upper portion.

14. A control device comprising;

a base member of insulating material,

a switch mounted on the base member including,

first and second fixed contacts,

a cam rotatably mounted on the base member,

a post rigidly secured to the base member,

a sleeve rotatably mounted on the post,

a cam follower mounted on the sleeve and biased into engagement with the cam,

an auxiliary armature member on the base member displaced from the switch,

a spiral bimetal element secured at one end to the sleeve and disposed in a plane parallel to the base,

a wall plate secured to the base member,

heating control terminal connector, a power source terminal connector, and a cooling control terminal connector on the wall plate,

a conductor electrically connecting the resistor to the heating control terminal,

a conductor electrically connecting the movable contact to the power source terminal,

and a conductor electrically connecting the first fixed contact with the cooling control terminal.

15. A control device comprising;

a base member of insulating material,

electrical switch means on the base member,

a cam follower rotatably received on the shoulder,-

a bimetal element secured at one end to the post for operating the switch in response to ambient temperature variations,

.a resilient spring washer mounted on the post between the cam follower and bimetal element for frictionally restraining the cam follower against rotation relative to the post,

and a cam rotatably mounted on the base member operatively engaging the cam follower for varying the temperature response of the switch means,

said cam follower and post being selectively rotatable relative to each other for calibrating the position of the bimetal relative to the cam.

16. A control device as defined in claim 15 further comprising;

.an arcuate slot formed in the base member, a cut-oif lever for resiliently urging the free end of the bimetal away from the switch means, including; an apertured lug mounted on the rear face of the base member, and a resilient arm member projecting through the arcuate slot into the path of the free end of the bimetal to augment the opening force of the bimetal. 17. A control device as defined in claim 16 further comprising;

a lever arm extending from the cam follower,

a stop post projecting from the front face of the base member into the path of movement of the lever arm upon rotation of the post and bimetal,

said lever arm engaging the stop post to permit relative rotation between the cam follower and bimetal to selectively vary the calibration of the cam follower with respect to the bimetal.

18. A control device as defined in claim 10 including;

an anti-torque washer having an apertured concave portion received on the post between the rotatable element and the cam follower,

a stop post projecting from the base member,

and a locking leg extending radially from the concave portion of the anti-torque washer and connected with the stop post to frictionally restrain the rotatable element against rotation when the cam follower is rotated relative to the bimetal.

19. A control device comprising;

a base member of insulating material,

a post rotatably secured to the base member,

a pair of heat anticipating resistance coils secured to the base member on opposite sides of the post,

a contact Wiper blade rotatably mounted on the post and having oppositely disposed arcuate wiper contacts electrically engaging the resistance coils,

a shoulder on the post,

an anti-torque washer having an apertured concave portion received on the post between the shoulder and the contact wiper blades with the rim of the concave portion frictionally engaging the contact Wiper blades,

a stop post projecting from the base member,

locking leg extending from the concave portion of the anti-torque washer,

a recess on the end of the locking leg interengaged with the stop post to prevent rotation of the antitorque washer relative to the post,

a magnetically responsive switch mounted on the base member,

a cam rotatably mounted on the base member,

a cam follower mounted on the shoulder and biased into engagement with the cam;

a fixed armature member mounted on the base displaced from the switch,

a spring washer received in the post between the bimetal and cam follower frictionally restraining the cam follower against rotation relative to the post and bimetal, and a lever arm projecting from the cam follower,

said lever arm being engageable with the stop post upon rotation of the post and bimetal to permit selective relative rotation between the cam fol- 20 '20. A control device as defined in claim 19 including; a cut-off lever mounted on the base member having a resilient arm member projecting into the path of the free end of the bimetal to resiliently augment the force of the bimetal urging the magnet toward the stationary armature.

References Qited by the Examiner UNlTED STATES PATENTS 2,262,343 11/41 Shaw 200122 3,046,375 7/62 Houser 200-122 3,051,001 8/62 Laviana et al. 200122 3,068,333 12/62 Hewitt 20087 lower and bimetal for calibrating the position 15 BERNARD A. GILHEANY Primary Examiner of the bimetal relative to the cam.

Claims

7. A CONTROL DEVICE COMPRISING: A BASE MEMBER OF INSULATING MATERIAL, A SWITCH MOUNTED ON THE BASE MEMBER INCLUDING, FIRST AND SECOND FIXED CONTACTS, A MOVABLE CONTACT BIASED INTO ENGAGEMENT WITH THE FIRST FIXED CONTACT AND MAGNETICALLY RESPONSIVE TO ENGAGE THE SECOND FIXED CONTACT, A CAM ROTATABLY MOUNTED ON THE BASE MEMBER, A POST RIGIDLY SECURED TO THE BASE MEMBER, A SLEEVE ROTATABLY MOUNTED ON THE POST, A CAM FOLLOWER MOUNTED ON THE SLEEVE AND BIASED INTO ENGAGEMENT WITH THE CAM, AN AUXILIARY ARMATURE MEMBER ON THE BASE MEMBER DISPLACED FROM THE SWITCH, A SPIRAL BIMETAL ELEMENT SECURED AT ONE END TO THE SLEEVE AND DISPOSED IN A PLANE PARALLEL TO THE BASE, AND A MAGNET CARRIED BY THE FREE END OF THE BIMETAL ELEMENT FOR MOVEMENT BETWEEN THE SWITCH AND THE AUXILIARY ARMATURE IN RESPONSE TO AMBIENT TEMPERATURE VARIATIONS TO ACTUATE THE MOVABLE CONTACT OF THE SWITCH BETWEEN THE FIRST AND SECOND FIXED CONTACTS.