US2587334A - Control device - Google Patents

Description

Feb. 26, 1 52 c. G. KRONMILLER CONTROL DEVICE 2 SHEETS-SHEET 1 Filed Sept. 2. 1949 INVEN TOR. (7 6- XFdNM/LLEE Feb. 26, 1952 c. G. KRONMILLER CONTROL DEVICE 2 SHEETSSHEET 2 Filed Sept. 2, 1949 INVENTOR. 64.84 GI K/EONM/LLEE 172550 rneg Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE CONTROL DEVICE Carl G. Kronmiller, Edina, Minn., assignor to Minneapolis-Honeywell Minneapolis, Minn., a corporation of Delaware Application September 2, 1949, Serial No. 113,884

9 Claims. 1

This invention is directed to a control point adjusting means applicable to thermostats and other condition controlling devices.

An object of the invention is to provide a control device having adjusting mechanism including a pair of manually positionable cams, one of which adjusts the control point and the other of which positions a pointer with respect to suitable indicia to indicate the selected control point.

Another object is to provide a control device having a knob that may be manually rotated to adjust and indicate the control point and that may be moved axially to actuate a switch controlling a light bulb disposed to illuminate the indicia of condition value.

.Other objects will be evident from the following description and claims, and fromthe drawing, in which ,Figure 1 is an elevation of a room thermostat embodying the invention, the cover being re-. 'moved and certain parts broken away for the sake of clarity,

Figure 2 is a fragmentary section taken on line 2-2 of Figure 4 showing details of the cam adjusting mechanism,

Figure 3 is a fragmentary section taken on line 3-3 of Figure 4 showing details of the connection between the cam structure and the rod that positions it,

Figure 4 is an elevation taken in section along line 44 of Figure 1, the cover also being shown in section, a

Figure 5 is a rear elevation of the device of Figure 1, and

Figure 6 is a diagrammatic view showing an electrical circuit in which the'thermostat may be used.

While the invention is applicable to various control devices, it is illustrated in connection with a thermostat adapted to control the supply of heat to a room. The thermostat has a base ID of suitable insulating material such as molded Bakelite, the back surface being recessed as at H to receive a wall plate (not shown) to which connecting wires may be secured and to which the thermostat itself is secured by its terminal screws in a manner well known in the art. A bracket I2 is secured to the front surface of the base ID by screws l3 and M, the screw l3 extending through the base to electrically connect the'bracket |2 to a conducting strip |5 shown in Figure 5. The strip |5 carries a terminal screw Hi, the slotted head of which is accessible from the front of the base through a hole therein.

The bracket |2 has an outwardly extending portion |2a at its right hand end which carries a Regulator Company,

spring blade 20. A switch arm 2| is secured to the blade 28 adjacent the bracket portion l2a, the intervening portion of the blade 20 serving'as a spring hinge for the switch arm. A movable contact 22 is mounted on the right hand end of the blade 20 and is biased with respect to the switch arm 2| by the blade 20 to provide a limited amount of press back as disclosed in my copending application Serial No. 681,461, filed July 5, 1946, now Patent No. 2,493,294, dated January 3, 1950.

Another bracket 25 is secured to the front surface of the base In at the lower right hand corner by screws 26 and 21, the screw 26 extending through the base to form an electrical connection with a conducting strip 28 on the rear surface thereof. A terminal screw 29 is held on the base IE] by the strip 28 and an opening is provided in the base and in bracket 25 to permit access to the screw head. A contact screw 30, the upper end of which is adapted to cooperate with movable contact 22, is adjustably carried in the bracket 25. The bracket 25 also carries a permanent magnet 3| which cooperates with the switch arm 2| to cause snap action of contact 22 into and out of engagement with stationary contacts, the switch arm 2| being made of suitable magnetic material to act as an armature for the magnet 3|.

A pivot pin 34 is mounted on th left hand end of bracket l2 and extends outwardly therefrom normal to the base ID. A member 35 having a horizontally disposed bimetal element 36 secured thereto is pivotally mounted on the pin 34, the member 35 having an extension 35a the right hand end of which carries a calibrating screw 38 which engages an adjusting'cam to be hereinafter described. The right hand end of the bimetal element 36 passes through an opening in a very thin strip Ml which is secured to the extremity of the switch arm 2|. As seen in Figure 4 the strip 40 has a very narrow portion intermediate the bimetal 36 and switch arm 2| to render the connection very flexible. This connection between the switch arm and the bimetal element is instrumental in providing a clean snap action of the switch contact since the strip 4|! flexes sufiiciently during the snap action to prevent sliding action between the strip and the bimetal element.

An anticipating heater 43 is secured to bimetal element 35 by a screw 44 which passes through an insulating washer 45, a conducting washer 46, and is screw threaded into the member 35. Heater 43 is preferably of cylindrical form and is made of a suitable carbon or graphite composition to provide the desired resistance. A pigtail connection 48 connects the washer 45 with a screw 49 that extends through the base Hi to form an electrical connection with a conducting strip 50 on the back of the base. A terminal screw 5| is carried in the base it by the strip 55.

A molded plastic cam shaft 55 has a reduced cylindrical end portion 55 that is journaled in the base 15, as is shown in Figure l. The outer end of the cam shaft 54 is also provided with a.

cylindrical bearing portion 55 journaled in a bracket 58, the major portion of which is spaced which also cooperates with the indicia on the;

scale plate 66 to indicate existing temperature. The scale plate 52 i is provided with a slot 6'! that serves as a guide for a pointer t8 which cooperates with the indicia to indicate'the adjusted temperature at which contacts 22-30 will be engaged to call for heat. Thepointer G8 is. provided with a .rearwardly extending pin lfi'which. is connected by a link it? to a pin "M. extending A cam 82, molded integrally with theparallel to the pin it from a lever '55 which is.v

pivoted on a pin 3'5 in the bracket 55." 12 comprises an upper relatively rigid member 7211. which is formed at either end to engage pins 10..andjl l, and a lower springstrip 72?) which. holds the pins inengagement.withnpperportion 12a... This constructionpermits ready assembly.

of the pointer 58 onscale plate 64 andalso prevents. lost motion, between the pointer. and the.,

lever 78. Thelower end of. the lever 1511s,. U..-

shaped. and the rear leg forms. a cam follower.

85 which is biased by a spring (li-intoengager.

ment with a cam that is molded integrally It will benoted thatas. the cam shaft 54 is rotated to adjust cam. 52,.

with the cam shaft 5%.

and hence the bimctal elements, to determine the control point of the thermostat, cam. 52 is, also positioned to adjust lever it andthenceuthe,

pointer 68'to indicate the control point. Thebir metal supporting member is biasedby a spring;

83 in a clockwise direction to assurepositivaen;

gagement of the calibrating screw. with the.

The action of spring makesit more difiicult to adjust the cam 52. in.

surface of the cam. 52.

a counterclockwise direction than in a clockwise direction. On the other hand, spring E5! biases the cam follower. 550 against the cam 82 (which is oppositely disposed h respect to the cam 62) making it more difficult to adjust the cam 82 in a clockwise direction than in a counterclockwise direction. The combined effect of the springs 83} and tlion the cam shaft 5:?- results in there being very little difference-in the force required to rotate it in the opposite direction.

Scale plate 64 isformedof a translucent material and is adapted to be illuminated by a light.

bulb 85 having a conducting; base 85 secured in place on the base it by a strip 8'! which grasps the base 88, extends along the base ill and is secured thereto by a screw 88. The screw 88 extends through the base and forms an electrical. connection with a conducting; strip 39.

The link.

The base i5 and strip 89 are provided with openings through which the head of a terminal screw 99 is accessible. A conducting strip 92 ofre silient material is secured to the rear side of the base as seen. in Figure 5 by a pair of rivets 93 which also secure a strip of insulating material in overlyingrelation withrespect to the conducting strip 92. An extension 92a :ofithe strip 92 extends outwardly through an opening in base ill to engage the center terminal connection of the light bulb 85. The lower end 5212 of the strip SZextends through an opening in the in sulating .strip fi l and overlies its lower extremity. Thestripportion92b' is disposed to lie underneath but spaced .fcm an extension a of the conducting strip which carries the terminal screw'5i.

The strip portion 92b is normally out of engagement with the conducting strip 50 but may be forced into engagement therewith by a pin 96 that extends axially through the base I 0, the. The outer, end oi the pin 925 carries an adjusting knob 98by cam shaft 5 1, and the bracket 58.

means of which the pin 96 can be rotatedand strip 5i cooperate to forma switch in theglight bulb circuit extending from the terminal screw;- 98. throughthe strip. 87, the light bulb 85and through the. strips 92'. and.5fl-. to the. terminal: screw 5 i.

As best seen in Figure 3 thepin .96 is laterally v bored to receive a pin I00 which has a force fit therein. Pin lilfl extends laterally through a-slot in the inner end of the cam shaft 54. The pin I00 keys the pin'96 to-the cam shaft 54 so-that rotational movement of theknob 98 will be-im parted to the cam shaft 54 but axial movement" of the knob 98 and the pin 96 will be'perrnitted with respect to the cam shaft to actuate the switch 92b-50a.

As seen in Figure 4 a cover-"I02 is securedfto the base Ill and encloses the base and all ofthe described mechanism with-theexception of outer;

portion of the knob 98 which extendsthrqugh a suitable opening therein. A transparent wing dow I03 is providedin the cover IUZadJ'acent the indicia on the scale plate 64, the thermometer tube andthe pointer 68..

Under conditions of normal illumination in the room in which the thermostat is installed'the knob 98 may be rotated to adjust. control'point of the instrument and to indicate it on scale plate 64. However, there aremany times when it is. desirable, as. when retiring at. night, to, ad:

just the thermostat without turning. on, general;v room illumination. Under these conditions thev thermostat may be adjusted bypushing inon the; knobflil to energize the light bulb while; ro-

tating the knob 98 to select thedesired tempera-1 ture. It. is also possible, of course, tov employ. this light. source to merely check the adjusted.

positionof the pointer 68 or to read the ther-\ mometer.

One possible electrical circuit in which this thermostat may be employed is-shownin Figure-- 6. A transformer I05 havinga lowvoltage secm ondary winding I06 may serve as. a source of The thermostat may be'used' electrical current. to control any commonload llllsuchasa solenoid gasvalve, oil burner-relay or the like. The

main control; circuit extends; from theitranseformer secondary I06 through a wire I08 to the load I01 and through a wire I09 to the terminal screw I6. Current is conducted through the bracket I2, switch arm 2|, contacts 2230, and the bracket 25 to the terminal screw 29, and thence through a wire IIO to the opposite side of the transformer secondary I08. It will be evident that the load I! will be energized whenever the thermostat contacts are closed. The left hand connection of the transformer secondary I06 is connected to the terminal screw 5| by a wire III which energizes the anticipating heater 43 through the pig-tail 48. The opposite connection to the heater 43 is through the bimetal element and through the member 35 and pin 34 to the bracket I2 which is connected to the opposite side of the transformer secondary whenever the thermostat contacts are closed. Thus heater 43 will be energized whenever the thermostat calls for heat and the heater 43 will supply additional heat to the bimetal element to cause the thermostat contacts to open after an interval of time whether heat is actually supplied to the room or not. When the knob 98 is pushed inwardly the switch 50a-92b will be closed and a circuit will be completed to the light bulb 85 from the terminal screw 5| through conducting strips 50 and 92 to the light bulb 85. Conducting strip 81 connects the base of the light bulb 85 through the terminal screw 90 and a wire I I3 to the terminal screw 29.

While the invention has been described in connection with a room thermostat adapted to control a heating system it will be evident to those skilled in the art that it could be equall well applied to a cooling thermostat or for that matter to any other condition controlling device, for example, a room humidostat. Likewise, the in- 3. In a control device, a base, a thermostat on said base, a first cam for adjusting the control vention is applicable to any control device where it is desirable to adjust the control point and indicate it at the same time. Many modifications of the invention will be apparent to those skilled in the art and I am therefore to be limited only by the appended claims.

I claim as my invention:

1. In a thermostat, a base adapted for mounting on the wall of a room, a thermostatic element pivotally mounted on said base, a switch actuated by said thermostatic element, a cam for pivotally positioning said thermostatic element to determine the temperature at which said switch is actuated, a plate carrying indicia of temperature and a pointer movable with respect ihereto, a lever pivoted in said base for posit1oning said pointer with respect to said indicia, a cam for positioning said lever and means for rotating simultaneously both of said cams, said pointer indicating the temperature at which said thermostatic element actuates said switch.

2. In a thermostat, a base adapted for mounting on the wall of a room, a thermostatic element pivotally mounted on said base, a switch actuated by said thermostatic element, a cam for pivotally positioning said thermostatic element to determine the temperature at which said switch is actuated, a plate carrying indicia of temperature rectilinearly disposed thereon and a pointer movable rectilinearly with respect thereto, a lever pivoted in said base for positioning said pointer with respect to said indicia, a

link interconnecting said lever and said pointer,

point of said thermostat, a temperature indicator carried by said base, a second cam for adjusting said indicator, a light bulb for illuminating said indicator, a switch controlling the circuit for said bulb, and manually operable means including a member extending through both of said cams for rotating said cams, said member also being axially slidable in said cams to actuate said switch.

4. In a control device, a base, condition responsive means and control means carried on said base, cam means for relatively positioning said means to adjust the condition value at which said control means is actuated by said condition responsive means, an indicator comprising a pointer and indicia of condition value, a linkage interconnecting said cam means and said indicator for causing said indicator to show the condition value at which said control means will be actuated, a lamp bulb disposed to illuminate said indicia and said pointer, a switch controlling energization of said lamp bulb, and manually positionable means rotatable coaxially with said cam to adjust the control means and slidable axially with respect thereto to actuate said switch.

5. In a control device, a base, a member pivoted in said base, a bimetal element attached to said member, a switch actuated by said bimetal element, an indicator comprising a relatively movable pointer and indicia of temperature, a lever pivoted in said base and a connection between said lever and said indicator, cam-means pivoted in said base and engaging said member and said lever, a knob. rotatable to adjust simultaneously said bimetal and said indicator, a light bulb disposed for illuminating said indicator, and a switch in control of said light bulb, said switch actuated by axial movement of said knob.

6. In a control device, a base, a member pivoted in said base, a bimetal element attached to said member, a switch actuated by said bimetal element, an indicator comprising a relatively movable pointer and indicia of temperature, a lever pivoted in said base and a connection between said lever and said indicator, cam means pivoted in said base and engaging said member and said lever, manually positionable means including a rod extending axially through said cam means and keyed thereto, a light bulb disposed to illuminate said indicator, and a switch in series circuit with said light bulb, said rod extending through said base to actuate said light switch on axial movement of said manually positionable means with respect to said cam means.

7. In a control device, a base, a thermostatic element and a switch on said base, a bracket on said base having a portion parallel to said base but separated therefrom, a scale plate carried by said bracket, a pointer movable with respect to said scale plate to indicate the temperature at which said element will actuate said switch, a cam pivotally mounted between said base and said bracket portion and confined thereby against axial movement, connections between said cam and said element and between said cam and said pointer, a rod disposed coaxially of said cam and having a knob at its outer end, means interconnecting said rod and said cam causing concurrent ivotal movement thereof but permitting relative axial movement therebetween, a light bulb adapted to illuminate said scale plate and pointer, and a switch in circuit with said light 7 nlbiaacfiuat i; he, nner n of 1 a 99 axiaimnv ment hereon,

imsaidbase for, positioning said pointer with re,-v

spectto said indicia; a link interconnecting said 1eyer and said pointer, acam for positioning saidg lever, and means for rotating simultaneously -both of-saidcams, said pointer indicating the em r t e-at i h.saidt e m a m n etu es i sw h:

9-, lmacontrol device, a base, a thermostat on said, base, a unitary cam structure pivotally mountedon saidbase andhaving first and sec- 0nd spiral earn surfaceswith-their effective sur-u faces ing ite dir c ions hrwe muip ed t rmine an pi n ul r movement. againfollower connected to said thermostat engaging said first cam surface,- an indicator, a cam fol;

lower connected to said indicator engaging said secondcam surface, and means biasing each of said cam? followers into engagement with said:

cam surfaces.

CARLHG. K O M -LER.

REFERENCES CITED The following references areof record in the file of this patent;

UNITED STATES PATENTS um am M:v

1,639,618 h r "r'ft'ffffr't"? 1,711,931 Farrington May 7, 1929 2,051,181 Saar Aug. '18; 1936' 2,124,089 Stuerzl July 19,1933; 2 2 ,3 ickmeya J e, 9. 2 2 2? i ma nei at O t. .950

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