US2558617A - Clock thermostat - Google Patents

Description

June 26, 1951 c. G. KRONMILLER CLOCK THERMOSTAT 3 Sheets-Sheet 1 Filed Jan. 14, 1948 June 25, 1951 c. G. KRONMILLER 2,558,617

CLOCK THERMOSTAT Filed Jan. 14. 1948 3 Sheets-Sheet 2 Gttorneg June 26, 1951 c. G. KRONMILLERA 2,558,617

CLOCK THERMOSTAT Filed Jan. 14, 1948 3 Sheets-Sheet 3 :inventor Cam. G. Mmm/LLM Gttorneg Patented June 26, 1951 oLoox TmnMosTaT Mon-1 G xmnmiuer, Edina, Mmm, mmm to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 14, 1948, Serial No. 2,230

. c ,1 s l The present invention is directed to' a control device whose control point is adapted to be shifted by a clock mechanism. More particularly the invention is directed toa clock thermostat that is adapted to maintain one' temperature during the day and a reduced temperature'during the night or during periods of non-occupancy.

'An object of the invention is to provide a control device having a clock mechanism for shifting the control pointbetween two adjustable values.

Another object is to provide a time adjusted control device having means extending outside the housing Vfor the device for setting the high and low control points in a convenient manner.

A further object is to provide a clock thermostat in which the day and night temperature settings are selected by a pair of levers having their ends extending beyond one end of the instrument case and cooperating with a temperature scale at the end'of the case.

A further object of the invention is to provide a clock driven cam having an adjustable raised portion for shifting a member between adjustable abutments to vary the control point of a condition responsive device.

Another object is to provide an adjustable cam, the raised portion of which may be adjusted to cover a maximum arc that is more than twice the minimum possible arc.

Another object is to provide a novel cam for shifting control point between day and night settings that is rotatable with a twenty-four hour dial and has pointers adjustable with respect to the dial to determine the times at which the control point will be shifted.

Other objects will be apparent from the following written description and claims, and from the drawings, in which Figure l is a face view of a clock thermostat with certain parts broken away and with the mechanism in a position to control at a selected reduced temperature;

Figure 2 is a bottom view of the instrument shown in Figure 1 with certain parts broken away and certain parts in section;

Figure 3 is a fragmentary view of the mechanism illustrated in Figures 1 and 2 with the instrument base eliminated and with the parts in a position to control at a selected elevated temperature; f

Figure 4 is a view of the composite cam adjusted to provide the maximum effective raised proiile, and

Figure 5 is an exploded view of the twenty-four hour dial and cam assembly.

is claims. (ci. zoo-136.3)

morning. Provision is also made for selecting the desred day and night temperatures. A feature of the ldescribed device is that the day andnight temperature selecting levers extend outside the housing of the device and may be adjusted -to maintain a constant temperature when the ocev sion arises. Referring now to the drawing, the clock ther-l mostat has a generally fiat and rectangular'base lli which is adapted for mounting on a vertical wall surface of a room. The base Il is recessed on its underside to facilitate wiring thev device and also to accommodate the temperature adjusting levers as will hereinafter appear. A cover or screen Il in the form of an inverted box with-its open side resting against the base Il encloses the clock mechanism, thermostat, and adjusting mechanism. The top and bottom surfaces'ofl the screen Il are provided with a plurality of openings I2 to permit room airto circulate through the screen H and over the thermostatic element. 'I'he openings I2 are also beneilcial'in conducting heat away from the clockmechanism which is preferably of the type operating onv regulated frequency alternating current. 'I'he screen I I is provided with suitable projections that enter openings in the base i0 so that the cover may be fixed in place by tightening a pair of screws Il extending 'through the upper and lower edges of the bsse.- An opening in the front face oi' 'the screen Ii is covered with a clear plastic dial il which carries the clock numerals and through which the clock hands are visible.

Since, for the purposes of the presentdisclosure, the clock mechanism may be of any type either spring wound or electric, no details of the mechanism have been shown and it is illustrated as being contained in a clock housing It suitably secured-to the base I0. Besides driving the clock hands the clock mechanism also drives a twentyfour hour dial Il through a suitable gear train I! terminating in the -gear 2| which is rigidly aty tached to the dial I8 and rotatable therewith.

An adjustable cam assembly generally indicated at 2t is rotatable with the dial il and together with the dial Il is rotatable on a pin 2l which pending design application Ser. No. D. 138,361,

led April 14, 1947, now Patent Des. 151,905.

The base III is made of suitable insulating material such as molded Bakelite and carries brackets 3l and 3l which are electrically con- Anected to the binding screws 32 and 33. The

The bracket 36 carries an adjustable contact 35 and the bracket 3| carries an adjustable contact 36.l A bracket 36 mounted on the lower edge of the base is electrically connected to a terminal screw 33 and has an upstanding portion 40 to which is attached a resilient blade 4I. A contact arm 42 is secured to the blade 4I adiacent the bracket 48 and extends upwardly'to carry a movable contact 43 that cooperates with the stationary contact 36. The blade 4I also extends upwardly to carry a contact 44 that cooperates with stationary contact 35. The blade 4I and .-arm 42 are formed so that the portion of the blade 4I between the bracket 46 and its connection to the arm 42 biases contact 43 into engagement with the stationary contact 36. The upper extension of the blade 4I passes through an opening in the arm 42 and is biased lightly into engagement with the right hand edge thereof. Stationary contact 35 is adjusted So that it will engage the contact 44 and press the blade 4I back slightly with respect to the arm 42 before contact 43 can engage the contact 36. f This ycontact structure. together with the thermostatic element to be described later, is the subject of my co-pending application, Ser. No. 681,442, led July 5, 1946, now Patent Re. 22,998.

As mentioned above, both sets of contacts are biased to closed position by the resilient blade 4 I. The contacts may be separated by a U-'shaped bimetallic thermostatic element 46 that is adapted to engage an abutment 41 on the upper extremity of the contact arm 42. The bimetal element 46 is pivoted on a pin 48 extending upwardly from the bracket 38. The temperature at which the element 46 will separate the contacts depends on the position of the upper end of the right-hand leg of the element. A pivot pin 50 extends outwardly from the base iand has pivoted thereto a member I that is connected to the right hand leg of the bimetal 46 by a link 52. A member 54 is also pivoted on the post 56 and normally moves with the member 5I. However, an eccentric 55 pivoted in the member 54 and engaging the member 5i adjusts the relative angular position of the two members about the pivot pin 50 for calibrating the device. A pin 51 carried bythe left-hand end of the member 54 extends through an opening 58 in the base I0 and is adapted to engage portions of a day temperature adjusting arm 66 and a night temperature adjustment; arm 6I 'which are pivoted in the base I0 on a bolt 63. A pair of friction washers 64 are interposed between the arms 60 and 6l and between a spring washer 65 and the head of the bolt 63. The washers 64 are provided with ears 66 that engage a portion of the base I0 to prevent rotation thereof, The right hand extremity of the arms 66 and 6l extend through an opening in the base and underneath a scale plate carried at the right-hand-end of the base' I6. The indicia on the plate 19 are located so as to be visible' when the screen II is in place and provide for adjustment of. day and night temperatures without removing the screen Ii. Screws 1I and 12 are adapted to lock the arms 60 and 6I to the plate 10 in prevent unauthorized adjustment of ternperature settings if desired..

Without reference to the function of' the cam and camV follower to be described below. it will be seen that the resilient blade 4I tends to maintain the contacts in closed position and through the arm 42 and its abutment 41 tends to move the bimetal element 46 in a clockwise direction and places the link 52 in compression to move the member 5I and member 54 in a clockwise direction so that the pin 51 is in engagement with vthe day temperature adjusting arm 60, as shown be controllable by the day temperature adjusting arm 60, since it is only by engagement of the pin 51 on member 54 with this arm that the bimetal element 46 will be able to expand to move the contacts to open position against the action of the resilient blade 4 l A cam follower 15 is also pivoted on the post 56 and it is provided with a roller 16 that engages a Ycam 23. The cam follower 15 is provided with a lower extension 18 that extends generally parallel to the member 54 and is adapted to engage a screw 19 carried by member 54.

A spring 8l extends between the portion 18 of the cam follower 15 and an extension 83 of the member 54 and serves to bias the cam follower to a position where the extension 18 engages the `screw 19. The purpose of the abutment between the extension 18 and the last member 54 is to limit relative rotation therebetween and to.

eliminate the biasing effect of the spring 8| on the member 54 when the roller 16 of the cam follower 15 is out of engagement with cam assembly 23, thus permitting the resilient plate 4I to bias the member 54 into engagement with the day temperature adjusting arm 56 as above described. The screw 19 is adjusted so that the roller 16 will not engage the low portion of the cam assembly 23 when the day temperature setting arm- SI1 is raised to the highest possible temperature setting. Adjustment of the screw 19 should also be such that when the roller 16 of the cam follower 15 is on the high part of the cam and the night temperature adjusting arm 6I is'at its lowest possible setting, there will be some clearance between the screw 19 and the extension 18 of the cam follower to assure that the pin 51 is held in engagement with the arm 6I. Thus it will be seen that the diiierence in radii between the low and high portion of the cam should be suiiicient to move the cam follower 15 through an angle slightly greater than the possible angular movement of the member 54 as determined by the maximum temperature setting of the arm and the minimum tempera- With this construction, no great accuracy of the cam profile is required. Consequently the cam disks can be made by simple stamping operations.

As mentioned above, the dial I8 and the cam assembly 23 are rotatable on a pin 25 carried by the extension 26 of the clock motor housing I6. Cam assembly 23 comprises four similarly shaped disks 85, 86, 81 and 88, as shown in Figures 4 and 5. The lower disk 85 is fixed to a sleeve 80 that is directly rotatable on the pin Il. v'lfhe sleeve vll is fluted as at' il. tecooperate with complementaryprojections 02 on a pointer C3 which cooperates with thedial il to indicatethe time at which the thermostat will be adjusted fromthe high temperature setting to the low temperature setting. The upper cam disk I8 has a sleeve 95 fixed thereto which pivots on the sleeve Il attached to the disk Il. The sleeve has projections 56 thereon that cooperatewith complementary recesses 98 formed in a sleeve 91 attached to a pointer D! which cooperates with the dial I8 to indicate the time at which the temperature setting will be shifted from Vthat established by the adjusting arm il to that established by the adjusting arm 6l. The sleeve ll is threadedat its upper end to cooperate with a nut Ill that may be tightened to draw the cam disk and the pointer toward the dial II to lock-the parts to the dial so that they will be rotated as a unit by the clock motor.v A spring washer Il! is interposed between the disk 88 and the dial to-assist in so locking the parts together. The axially projecting lengths of the sleeves l and $1 as well as of theV projections 96 are such that suflicient axial movement is permitted to allow drawing the cam disk Il andthe pointer 9! tightly against the dial i8 as the nut itl is tightened on the sleeve Sii. Likewise the cooperation between the iluting-II in the sleeve st and the projection l! on the pointer 93 is such that axial movement of the parts is permitted as the nut I is tightened on the sleeve 96.

The cam disk 86 is provided with-a short lateral projection IM that cooperates with an arcuate opening |05 in the disk l5 to limit pivotal movement-between the two disks. With the projection l in one end of the slot |05 the contours of the two disks are. coincident while at the other-.end of the permitted movement the raised edges of the high parts of the cam cover an extended arc but no 'gap is permitted therebetween. The disk 86 is provided with an arcuate opening lli that cooperates with a projection lll on the disk 8l and likewise limits relative rotation between these two disks. Disk Il is also provided with a projection Ill that cooperates with a -radial opening Il! in the disk It for a similar Purpose. 'Ihe position of the lower disk Il relative to the upper disk Il and the position of the cam assembly relative to the dial Il may be adjusted by loosening the nut Ill, moving the pointers 93 and 9! to appropriate positions on the dial Il and retightening the nut lll.

As pointed out before, when the cam follower l5 is on the raised portion of the cam the thermostat will be adjusted to maintain the lower of the two temperature settings. When the pointers $3 and $9 are adjusted so that the cam disks l5 and ll are in coincidence thenthe intermediate disks 8i and Il will also be in coincidence therewith and the instrument will be adjusted to provide 'the minimum possible time of reduced temperature. In: the illustrated construction it will amount to approximately six hours. The maximum possible time of reduced temperature adjustment is provided when the Acam disks are adjusted to the position shown inFigure 4. It will be noted that the various projections and radial openings in the cam disk have caused the several disks. to be equally spaced and .to provide an effective raised vcam periphery that is somewhat more than twice topcam disk andthe bottom cam disk tl will dtermine thelimlts 0f tht elective l'isd Dol'- tion of thel cam,but the relative positions of the intermediate cam disks `will be definitely fixed only at the' and maximumpcssible cam adjustments.

1 the cam 2l has been adjusted to lowerthe temperature setting to that determined bythe arm 6| at eleven oclock. Since it is lnow approximately a quarter to one `asindieated by the clock hands, the cam, which is rotating counterclockwise, has raised the roller 1I of the cam follower 15 to raise the extension Il away from the abutment screw 19 and tension the spring Ilv to move the member 5I to a position determined by the temperature setting arm il. It should be pointed out here that the spring 8l issomewhat stronger lthan the resilient blade li and moves the contacts to open position through the bimetal element 45. However, when the room temperature is reduced sufficiently the bimetal element 4G will permit the resilient blade 4| to reclose the .v

contacts.

Although the pointer 93 is not visible in Figure l it is evident from the position of the cam segments that they have been adjusted to provide approximately eight hours of reduced temperature. Hence at about seven oclock the roller 16 of the cam follower 15 will ride oif the high surface of the cam and will be moved in a clockwise direction as the roller 16 moves down-the inclined surface of the upper cam disk. Ihe pin il on the member 54 will remain in engagement with the night temperature setting arm tl until the extension 'I8 of the cam follower engages the abutment screw l! on the lever 54. Further closkwise movement of the cam follower will permit the pin 5l to be moved from the arin 6l to the day temperature adjusting arm it duef to the bias of the resilient blade 4I. The parts will then be in the position shown in Figure 3; If the room temperature is suciently low, after the v contacts have been moved to closed position by the bias of the blade Il the bimetal element I8 may be out of engagement with the abutment 4l of the contact arm I2 and therefore will exert no clockwise force on the members Sl'fand M and the pin 51 may therefore be in engagement with neither of the arm ill nor 6|. Contacts will remain closed then until the room temperature rises sumciently to separate the legs ofthe U- shaped bimetal element 45 causing the member i4 to raise the pin 5l into engagement with the day temperature adjusting arm Gli. Engagement of the pin il and the arm 6h enables the element 4i to exert a thrust to open the contacts.

On continued counterclockwise movement of the cam the roller 'I6 of the cam follower l5 will be engaged by the inclined surface of the lower cam disk to rotate the cam follower in a counterclockwise direction and the pin 5l on the member ilwill start to move toward the adjusting arm 6i as soon as the cam follower starts to move. After the pin il engages the arm 6I the cam followerextension 'I8 will leave the abutment screw 19, and the pin 51 will be maintained against arm GI by the tension of the spring 8l. In this position of the parts the bimetal element 45 acts against an abutment established by the member 54 and the spring 8l to overcome the resilient blade Il in order to open the contacts.

'While the arrangement for providingv an adjustablehi'gh and low temperature setting and the cam structure for shifting between these two settings has been described in connection with a particular bimetal thermostat, it is obvious that other condition responsive means could be substituted without departing from the spirit of the invention. Instead of contacts operated by a thermostatic element it will be apparent that a control valve such as used in pneumatic thermostats might be substituted. Likewise, a volatile fill bellows might be substituted for the bimetallic element. Also, in the broader aspects of the invention, it is not essential that the device be used to control temperature, and a humidity responsive element might be substituted for a temperature responsive element where it is desired to maintain different humidity conditions at different times. p

The various features of novelty of the invention can be put into practice in apparatus taking many different forms and it is to be understood. therefore, that the scope of the invention is to be limited only by the appended claims.

I claim as my invention:

1. In a control device, a base, condition responsive means having a rst portion shiftable with respect to said base, a pair of adjustable stops limiting the range of possible shift of said condition responsive means, control means carried by said base and adapted to be actuated by a second portion of said condition responsive means at a condition value depending on the position of the first portion of said condition responsive means with respect to said base, a spring acting between said base and the second portion of said condition responsive means for biasing said condition responsive means to a position determined by one of said stops, and means for shifting said condition responsive means to a position determined by the other of said stops against the 'bias of said spring.

2. In a clock thermostat, a stationary contact,

a contact movable with respect to said stationary contact between engaged and disengaged positions, a spring biasing said movable contact toone of its operative positions, a clock mechanism, a cam driven by said clock mechanism, a cam follower, a member movable between first and second positions, a bimetal element interconnecting said member and said movable contact and adapted to move said contact against the bias of said spring, and a strain release conection between said cam follower and said member.

3. In a clock thermostat, a stationary contact, a contact movable with respect to said stationary contactbetween engaged and disengaged positions, a spring biasing said-movable contact to one of its operative positions, a clock mechanism, a cam driven by said clock mechanism, a cam follower, a pair of adjustable stops, a member movable between first and second positions determined by said stops, a bimetal element interconnecting said member and said movable contact and adapted to move said contact against the bias of said spring, and a strain release connection between said cam follower and said member.

4. In a clock thermostat, a stationary contact, a contact mo'. able with respect to said stationary contact between engaged andy disengaged positions, a spring biasing said movable contact to one of its operative positions, a clock mechanism, a cam driven by said clock mechanism, a cam follower, a pair of arms pivoted on the same axis and cooperating with a scale having temperature indicia thereon, a member movable between first and second positions determined by the positions of said arms. a bimetal element interconnecting temperature sensitive switch carried on said base,

a pair of adjusting arms, a member for adjusting the control point of said temperature sensitive switch, a clock driven cam and a cam follower connectedto said member for shifting said member between positions determined by said arms, said cam comprising more than two similarly contoured overlying sections each of which is provided with interlocking means cooperating with adjacent disks to prevent separation of the effective raised edge thereof, said interlocking means also causing coincidence of said sections at one extremity of adjustment thereof.

6. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controllingv means, a clock motor, a dial rotated by saidmotor, indicia of time on one surface of said dial, a composite cam comprising more than two of similarly contoured disks each havingraised and reduced peripheral portions pivoted coaxially with said dial and lying on the side of said dial opposite said indicia, a. pointer on the indicia side of said dial rotatable with one of said disks, a pointer on the indicia side of said dial rotatable with another of said disks, interlocking means acting between adjacent disks to prevent separation of the raised portions of said disks, and a cam follower operatively connected to said shifting means.

7. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controlling means, a clock motor, a dial rotated by said motor, indicia of time on one surface of said dial, a composite cam comprising a plurality of similarly contoured disks each having a raised and a reduced peripheral portion pivoted coaxially with said dial and located on the side of said dial opposite said indicia, a first pointer on the indicia side of said dial rotatable with the cam disk nearest said dial but slidable axially with respect thereto, a second pointer on the indicia side of said dial rotatable with the cam disk farthest from said dial but slidable axially with respect thereto, means for forcing said pointers and said cam disks against said dial to provide a unitary structure rotatable by said clock motor, and a cam follower cooperating with the raised portions of said cam disks operatively connected to said shifting means.

8. In a clock thermostat, temperature sensitive controlling means, means for shifting lthe control point of said controlling means, a clock motor, a dial rotated by said motor, indicia of time on one surface of said dial, a composite cam comprising a plurality of similarly contoured disks each having a raised and a reduced peripheral portion pivoted coaxially with said dial and located on the side of said dial opposite said indicia, a first pointer on the indicia side of said dial rotatable with the cam disk nearest said dial but slidable axially with respect thereto, a second pointer on the yindicia side of said dial rotatable with the cam disk farthest from said dial but slidable axially with respect thereto, means for forcing said pointers and said cam disks against said dial to provide a unitary structure rotatable by said clock motor, interlocking means acting between adjacent cam disks to prei ent circumferential separation of the raised portions thereof, and a cam follower cooperating with the raised portions of said cam disks operatively connected to said shifting means;

9. An adjustable cam assembly comprising a rotatable dial, indicia of time on one surface of said dial, a composite cam comprising a plurality of similarly contoured disks each having a raised and a reduced peripheral portion pivoted coaxially with said dial and located on the side of said dial opposite said indicia. a first pointer on the indicia side of said dial rotatable with the cam disk nearest said dial but slidable axially with respect thereto, a second pointer on the indicia side of said dial rotatable with the cam disk farthest from said dial but slidable axially with respect thereto, and means for forcing said pointers and said cam disks against said dial to provide a unitary rotatable structure.`

10. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controlling means, a clock motor, a dial rotated by said motor, indicia of time on one surface of said dial, a composite cam comprising a plurality of similarly contoured disks each having a raised and a reduced peripheral portion pivoted coaxially with said dial and located on the side of said dial opposite said indicia, a first pointer on the indicia side of said dial rotatable with the cam disk nearest said dial but slidable axially with respect thereto, a second pointer on the indicia side of said dial rotatable with the cam disk farthest from said dial but slidable axially with respect thereto, means for forcing said pointers and said cam disks against said dial to provide a unitary structure rotatable by said clock motor, interlocking means between said cam disks to prevent circumferential separation of the raised portions thereof, said interlocking means also causing alignment of all of said disks when said pointers are adjusted to a predetermined position for providing an effective composite cam surface having a minimum raised portion equal to the raised portion of one of said disks, and a cam follower cooperating with the raised portions of said cam disks operatively connected to said shifting means.

11. In a clock thermostat, a base, a thermostatic switch, a member pivoted on said base and connected to said switch for adjusting the control point of said switch, a pair of abutments for limiting pivotal movement of said member, a cam follower pivoted on said base coaxially with said member, cooperating abutments on said cam-follower and said member, a spring biasing the abutment on said cam follower into engagement with the abutment on said member and a clock driven cam for positioning said cam follower.

y 12. In a clock thermostat, a base, a' thermostatic switch, a first member pivoted on said base for adjusting the control point of said switch, a second member pivoted on said base coaxially with said first member, means for adjusting the angular relation between said members, a pair of abutments adjustable with respect to said base adapted to engage said second member for limiting pivotal movement of said second members, a cam follower pivoted coaxially with said members and having an abutment adapted to engage one of said members, a spring biasing said cam follower to a position determined by the position of said members, and a clock driven cam for positioning said cam follower.

13. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controllingmeans, a clock motor, a dial rotated by said motor. indicia of time on one surface of said dial, first and second pointers cooperating with said indicia, rst and 'second cam disks on the opposite side of said dial, a member extending through said dial and interconnecting said ilrst cam disk and said rst pointer, a member extending through said dial and interconnecting said second cam disk and said second pointer, a third cam disk intermediate said first and second disks, said cam disks, said pointers and said members being rotatably adjustable with respect to said dial about the pivotal axis of said dial, said cam disks being similarly contoured and having extended and reduced arcuate peripheral portions, interlocking means between adjacent cam disks preventing separation of the extended peripheral portions of said disks, said interlocking means also causing coincidence of all of said cam disks at one relatively adjusted position of said pointers, a cam follower adapted to engage the peripheries of said cam disks, and a linkage between said cam follower and said shifting means.

14. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controlling means, a clock motor, a dial rotated by said motor, indicia of time on one surface of said dial, first and second pointers cooperating with said indicia, first and second cam disks on the opposite side of said dial, a member extending through said dial and interconnecting said first cam disk and said rst pointer, a member extending through said dial and interconnecting said second cam disk and said second pointer, a third cam disk intermediate said first and second disks, said cam disks, said pointers and said members being rotatably adjustable with respect to said dial about the pivotal axis of said dial, said cam disks being similarly contoured and having extended and reduced arcuate peripheral portions, the raised portion of each cam disk including an angle of less than one hundred and twenty degrees, interlocking means between adjacent cam disks preventing separation of the extended peripheral portions of said disks, said interlock--4 ing means also causing coincidence of all of said cam disks at one relatively adjusted position of said pointers, a cam follower adapted to engage the peripheries of said cam disks, and a linkage between said cam follower and said shifting means.

l5. In a clock thermostat, a base, a thermostatic switch, a pivot post mounted on said base. a first member pivoted on said post for adjusting the control point of said switch, a second member pivoted on said post, means for adjusting the angular relation between said members, a pair of abutments adjustable with respect to said base adapted to engage said second member to limit pivotal movement of said second member for determining the control point of said switch, a cam follower pivoted on said post and having an abutment adapted to engage one of said members, a spring biasing said cam follower toward a position determined by the position of one of said members, and a clock driven cam for positioning said cam follower.

16. In a clock thermostat, temperature sensitive controlling means, means for shifting the control point of said controling means, a clock motor, a dial rotated by said motor, indicia of time on one surface of said dial, first and second pointers cooperating with said indicia, first and second cam disks on the opposite side of said dial, a member interconnecting said rst cam disk and said nrst pointer, a member interconnecting said second cam disk and said second pointer, a third cam disk intermediate said first and second disks, said cam disks, said pointers and said members being rotatably adjustable with respect to said dial about the pivotal axis of said dial, said cam disks being similarly contoured and having extended and reduced arcuate peripheral portions, interlocking means between adjacent cam disks preventing separation of the extended peripheral portions of .said disks, said interlocking means also causing coincidence oi' all of said cam disks at one relatively adjusted position of said pointers, a cam follower adapted to engage the peripheries of said cam disks, and a-vlinkage between said cam Vfollower and said shifting means.

.17.A In a clock thermostat, temperature sensi= tive controlling means, means for shifting the control point of said controlling means,.a clock motor, a dial rotated by said motor, `indicia of time on said dial, rst and second pointers cooperating with said indicia, first and second cam disks, a member interconnecting said first cam disk and said irst pointer, a -member interconnecting said second cam disk and said second pointer, a third cam disk intermediate said first and second disks, said cam disks, said pointers and said members being rotatably adjustable with respect to said dial about the pivotal axis of said dial, said cam disks having arcuate extended-peripheral portions of substantially iden- ,ticalV configuration, interlocking means between adjacent cam disks preventing separation of the i2 extended peripheral portions of said disks, said interlocking means also causing coincidence of the extended portions of all of said cam disks, at one relatively adjusted position of said pointers, a cam follower adapted to engage the peripheries of said cam disks, and a linkage between said cam follower and said shifting means.

18. An adjustable cam assembly comprising a rotatable dial having indicia thereon, a composite cam comprising a stack of disks pivoted coaxially with said dial, a rst .pointer cooperating with said indicia and rotatable with a first one oi said disks, a second pointer cooperating with said in relatively adjusted position of said pointers.

CARL G. KRONMILLER.

REFERENCES eraan The following references are ofrecord in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,231,686 Shaw' Feb. 11, ,1941 2,296,063 Shaw Sept. 15, i942 2,368,005 Crise Jan. 23, 1945

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