US2207946A

US2207946A - Mechanical timer

Info

Publication number: US2207946A
Application number: US177136A
Authority: US
Inventors: Sardeson Robert
Original assignee: McGraw Electric Co
Current assignee: McGraw Electric Co
Priority date: 1937-11-29
Filing date: 1937-11-29
Publication date: 1940-07-16
Anticipated expiration: 1957-07-16

Description

July 16, 1940. R. sARDEsoN l 2,207,9464

MECHANICAL TIMER y Filed Nov. 29, 19:57 4 sheets-sheet 1 ,B MMM y ttrneg.

July 1621940- R. sAR'DEso 2,207,946

1 MEGHANCAL TIMER Filed Nov. 29, 1957 4 sheets-sheet '2 F I y.

Ina/Grifo r: 'Rober-t Sar-desea,

July 16, 1940 R. SARDEsoN MECHANICAL TIMER Filed Nov29, 1937 4 Sheets-Shei 3 Inverdbg\-. 'Robert Sarfdson B54/ l Kum-nag.

July 16,1940. V R, SARDESON I y Y '2,207,946

MECHANICAL TIMER Filed Nov. 29, 19:57 4 sheets-sheet 4 Patented July 16; i940 i .l I y UNITED STATES PATENT oFFicE MECHANICAL TIMER Robert Sardeson, Minneapolis, Minn., assigner to McGraw Electric Company, Chicago, Ill., a corporation of Delaware Application November 29, 1937, Serial No. 177,136

l 15 Claims. (Cl. isi-116) lVLv invention relates totiming mechanisms broken away'and parts of the timer shown in and particularly to mechanical timers for conoperated positions, trolling the duration of an operating period of a Fig. 5 is a view similar to that of Fig. 4 showing masten parts of the timer and one of the bread slice 5 An object of my invention is to` provide a novel, supports in the positions which they occupy at 5 simple and highly eflicient mechanical timer for the beginning of a toasting operation, mounting on an electric toaster. v Fig. 6 iS a fragmentary VieW in Side elevation Another object of my invention is to provide a ShOWing Darts of the timenin the positions which meohanica1 timer adapted to' operate at a pluthey occupy at the end of the low speed operating ,l0 rality of different .substantially constant speeds. period, 10

Another object of my invention is to provide a. Fig. 7 is a fragmentary vVertical lengltudinal mechanical timer having a spring driven gear Sectional View,v on a Slightly enlarged Scale, train and a retarding means normally engaged taken 0n the line 'l-T 0f Fig, 2,

-therewith and disengageable therefrom by ther- Fig 3 iS a fragmentary SeCtiOnal VieW, 0n a l" mally-actuable means Ato cause 'the timer to op- Slightly enlarged scale, l similar to Fig. 7 but 15 crate rst at a relatively slow speed and then ShOWng the retarding meanS disengaged from at a higher speed. the gear train, I

Another object of my invention is to provide a Fig- 9 iS a fragmentary View; slightly enlarged, plural speed mechanical timer associated with a taken on the line 9--9 of Fig. 12, `2o toaster to'oontrol the duration of an operating Fig. 10 is a fragmentary horizontal sectional 20 period thereof by operating at onespeed for an VieW Slightly enlarged, taken 0n the line |0-.i0 initial period of time and then at a substantially 0f Flg 4,

higher speed, the instant of change from one Fig, 11 iS ya fragmentary horizontal Sectional speed to another being determined by thermal View, Slightly enlarged, taken on the line II-ll 25 means subject to toaster temperature. of Fig. 7, 25

Still another object of my invention is to pro- Fig- 12 iS a fragmentary Sectional View, Slightly vide a mechanical timer associated with a toaster enlarged, taken on the, line |2-l2 of Fig. r1, having a detent for holding parts of the toaster Fig- 13 is a fragmentary vertical sectional view, in operative position, the timer being operable Slightly enlarged, taken 0n the line |3-l3 of 30 in such manner as to make available substantial- Fig- 2, and 30 1y au of its power when acting on the detent to Fig- 14 is a fragmentary view, slightly enlarged, Cause release thereof and terminationof an in side elevation' of a modied form of certain operating period parts of the timer.

The novel features that 1 consider character- An automatic' electric toaster designated genrir istic of my invention are set forth in the ap- `erally by the numeral 2| includesa skeleton base 35 pondod claims, The invention itself however frame 23 which may be made of a suitable molded both as to its organization and its method of composition material and which supportsametal operation together with different objects and bottoni plate 25 Whlci) bottoni Plate may be Seadvantages thereof will best be understood from cured m pm per Operaftlve position in the frame 23 i0 the following description of a speciiic embodiby a plurality of Sultble Screws 2"- A Crumb 40 ment when read in connection with the accomtray 29 may 3.150 be smtablysecured to the Skele' panying drawings in which, ton frame 23 1n a manner well known in th'e art. Fig. l is a view in vertical longitudinal section, I have electefi to Illustratie a two'sli toaster taken on the line I-l of Fig. 2, through a. toaster rllthglrll gs rgniih't tg e udersopd thai; 'my 45 having associated therewith a timer embodying ve e ere o a. 1s applicable 45 to a toasterl adapted to toast any number of my invention: o slices of bread at a time. 'Ihe toaster as illus- Fig. 2-,is-a view 1n vertical lateral section therev trated provides a pair of electric heating elethrough taken 0n the lme 2*.2 0f Figl'ShQWmg ments for each slice of bread to be toasted therethe front interior of a toaster, partly 1n eleVain, each heating element including one or more 50 tion and partly. in section, l thin plates 3| ofelectric-insulating material such 3 iS a' fragmentary Sectional View 0n a vas mica, on which a resistor wire or strip 33 is slightly enlarged scale, taken on the line 3-3 wound, and while the resistor is positioned on of Fig. '7, that side of its support adjacent to the slice of Fig. 4 is a side elevational view with the casing bread to be toasted thereby I do not wish to be 55 a plurality of vertically-extending guard wires 35 to space a slice of bread from the heating elements and to maintain it in proper centered position between the two heating elements.

The lower ends of the respective plates 3| of 4electric-insulating material may have interiitting engagement with the bottom plate 25, while the upper edges thereof may be held by top frame plates 31 extending longitudinally of the toaster andby depending return-bent upper portions of the guard wires 35 in a manner now well known in the art.

The toaster includes also.a rear intermediate plate 39 and a front intermediate plate 4|, a toasting chamber being constituted by the front and rear intermediate plates and the outer vertically-extending heating elements. The toaster is further provided with an outer casing comprising vertically-extending walls 43 and acover member 45, the cover constituting the top wall of the toasting chamber and the base plate 25 constituting the bottom closure therefor. Side walls or bailie plates 46 located between the outermost heating elements and the side walls of the casing may also be provided.

A plurality of vertical standards 41, here shown as three in number, are positioned in a mechanism chamber 49 defined by the front intermediate wall 4| and the iront wall of the casing 43, the lower ends of these standards being supported by plate 25 while the upper ends are supported and held in proper operative positions by forwardly extending portions of the top frame plates 31 and by a crossbar 5| (see Figs. 1 and 2). A carriage 53 is adapted to move vertically on the intermediate standard 61, a plurality of rollers 55 being mounted thereon and engaging the standard to reduce friction therebetween.

A slider 51 is vertically movable on` the right hand standard 41 and a similar slider 59 is vertically movable on the lleft hand standard 41. Slider 59 has secured thereto a slotted plate 6| (see particularly Fig. 1) whereby to control a switch arm 63 which is insulatedly pivotally mounted on a bracket 61 supported on front intermediate plate 4|. Switch arm 63 is adapted to engage with and be disengaged from a fixed contact member 69 insulatedly supported on front intermediate plate 4| to control the 'energization of the hereinbefore described heating elements. An actuating knob 1| is mounted on carriage 53 outside of the casing to permit an operator to move itk downwardly thereby moving downwardly carriage 53 and the two

sliders

51 and 59. K

A bread slice support 13 is positioned between each pair of heating elements and the two supports are mechanically connected with the

sliders

51 and 59 as seen more particularly in Fig. l0 of the drawings, acrossbar 15 extending therebetween (see Fig. 10). A biasing means comprises a coil spring 11 positioned below the base plate 25, having one end thereof connected to the base plate 25 while the other end thereof is connectedto a short arm 19 ofv a Ibellcrank lever which is pivotally supported at 8|' -on vthe rear intermediate plate 39. The bellcrank lever includes also a longer arm 83 theforward end of which is slotted as at 85 (see Fig. l) the crossbar 15 being adapted to move 4in this slotted end. Spring 11 biases the bread slice supports to upper or non-toasting position and switch arm 63 to open position. Downward movement of knob 1| moves the bread slice supports into Y. their lowermost or toasting position and simu1. taneously causes closing of the switch. All of the hereinbefore described details areA well known in the art and reference may be had to Ireland Patent No. 2,001,362 for detailed descriptions thereof. It is to be noted that knob 1| and the movable parts associated therewith, are moved through a xed distance at each operation and that the timer spring is therefore wound up a predetermined amount irrespective of the duration of a toasting operation or of the duration of operation of the timer.'

able spacing rods 93 in a manner well known in the art. A clock spring 95 (Fig. 12) has one end secured to a spring arbor 91 while its other end may be secured to a short pin 99 (Fig. 2) mounted on side plate 9|. Arbor 91 has secured thereon at its other end, a pinion |0| which is in engagement with a vertically movable rack bar |03 which rack bar is moved downwardly when knob 1| yis moved downwardly as isclearly set forth in Ireland Patent No. 2,001,362. A grooved roller |05 holds the rack bar |03 in proper operative position and in mesh with pinion |0|. A ratchet wheel |01 cooperates with a pair of pawls |09 to permit of windingl up spring 95 by.

downward movement of knob 1| as is already well known in the art. The pawls shaft as is a second gear ||5. lGea"li'lmeshes with a pinion ||1 xedly mounted on the same shaft as is a gear I9. gears and pinions constitute a gear train. It is to -be noted that while I have illustrated a spring as constituting the prime mover my invention is not limited thereto as any other source of mechanical power may be used.

A retarding means adapted to be normally in engagementl with the gear train includes a pivotally mountedl reciprocable balance wheel |2| of the kinddi'sclo'sed and claimed in my copending application Serial No. July 8, 1937 and assigned to the same assignee as is the present application. Balance wheel |2| may be xediy mounted on a shaft |22 rotatably supported inside '.

plates

|09 aref. mounted on a gear which mesheswith' ;v pinion I3 which is xedly mounted on vthe same y has connected thereto one end of a coil spring.

|25, the other end of which is connected tol The other end of lever arm` balance wheel |2|. y |23 has connected thereto a connecting rodA |21 which is connected to a rotatable crank pin- |29Xy on a crank disc |3|. This crank disc is fi mounted on the same shaft whichfsupp disc 13| and pinion |33 is pivotally@ ir a swinging frame including side 'bars' which bars swing on a f shaft zi39- ..spivotailyf of the drawings, that during the unwinding of the spring 95 gear ||9 turns in a clockwise direction and that the tendency of the force transmitted thereby to pinion |33 tends to move the pinion out of engagement with the gear |'|9. I have found this to be an important part of the design and construction of my improved mechanical timer in that the amount of force required to effect this disengagement is relatively small.

The/method of operation of my improved mechanical timer is substantially as follows:

The retarding means above described is initially in engagement with the gear train for a length of time dependent on the duration of an operating period and upon the temperature of the toaster. It is well known that a toaster of this general type must be operated for a certain relatively long period of time in an initially cold toaster to obtain the desired degree of toasting of one or more slices of bread but that this voperating period decreases in length with increase in temperature. It is obvious, for instance, that if a mechanical timer of the kind thus far described had an operating period of saythree minutes and that the duration of an operating period of the toaster were alsov three minutes, it would be necessaryv for the timer to operate at the slow speed during the entire operating period of the toaster. It is further obvious that the period of operation of the timer at the slow speed decreases with the increase in the temperature of the toaster. I have found it desirable to determine the instant of change-over from low to high speed vby thermal means and to e'ect this change-over by mechanical means energized by the timer spring, and the mechanism for doing this will now be described in detail.

A disc |4| (see particularly Fig. 12 of the drawings) is xed on spring arbor 91 outside of spring 95 to turn therewith and it may be noted that this arbor turns through substantially 480 in one direction while the spring is being wound up, and in the opposite direction during unwinding of the spring which occurs during the operating period of the timer. This disc |4| has a spiral slot |43 therein which slot is adapted to' receive a pin |45 lixedly mounted at one end of a leverl arm |41 which lever arm is pivotally mounted intermediate its ends as on a fixed pivot |49 supported by outer side plate 9| of the timer. Fig. 5 of the drawings shows the position of the disc |4| and particularly of the spiral slot |43 therein and of the lever arm |41, just after knob 1| has been moved downwardly to the full limit of travel thereof.

Lever arm |41 has pivotally mounted thereon, an arm |59, of substantially L-shape, the two parts thereof being of different lengths. The long arm is pivotally mounted at its outer end on lever arm |41 intermediate the ends thereof and below pivot pin |49. A short pin |6| secured to arm |59 extends laterally inwardly therefrom for engagement with a cam surface |63 of detent |53 in a manner to be hereinafter 'described. Lever arm |41 has secured thereto at its lower end a latchreturning spring bar |65 which is adapted to engage latch |5| to cause movement thereof in a clockwise direction to thereby cause re-engagement of pinion |33 with gear wheel ||9.

A bimetal element |61 which may be of thekind disclosed and claimed in my copending application SerialNo. 127,100, led February 23, 1937 and assigned tothe same assignee asis the Ipresent application and now lPatent No. 2,171,895 granted Sept. 5, 1939, is provided. This bimetal element is supported by a bracket arm |69 which is slidably mounted against outer side plate 9| and which may be moved manually upwardly and downwardly by an actuating knob |1| in a man- No. 152,580, led July 8, 1937 and. assigned to the same assignee as is the present application. It;y

may be noted that bimetal elementv |61 is positioned adjacent to the toasting chamber, in an opening in one of the baille plates 46 and is subject to high temperature radiant heat from one ofthe hereinbefore described heating elements.

The bimetal element |61 is so designed and constructed that it will ex in a downwardly direction when subjected to an increase in temperature and its outer free en d has secured thereto a bent bar |13, the outer end of which ts into the forked end |15 on the short arm |59.

Fig. 6of the drawings shows the positions of the actuating knob I 1| and of the lever arm 41 as well as of bimetalelement |61 whenthe toaster has been heated to say its normal operating temperature and immediately after release of the retarding means from the gear train. It will be noted, by reference to Fig. 6 of the drawings, that the spiral slot |43 has been moved from its original position to a certain extent so that pin |45 is positioned therein intermediate-the ends of the slot. Lever arm |41 has been'turned on its pin |6| and cam surface |63 until nally detent n 53 and particularly the lower sharp end -|55 therefrom was moved out of engagement with latch |5|. This resulted in quick disengagement of pinion |33 from gear ||9, because of the direction of the force transmitted to pinion |33, and

a sudden speeding up of the'gear train.

Downward movement of knob 1| is utilized to wind up timer spring 95, carriage 53 being provided with a projection for engaging' a lug |8|JA at the lower end of rack bar |03. The rack bar is moved upwardly bythe timer during unwinding of spring 95, and-a cam surface |8| on projection |80 engages a lug |83 on a latch arm to cause turning movement thereof. The lower end of arm |85 provides a detent |86 for engaging with a projecting portion |81 of slider 51, whereby the bread slice supports are held in toasting position and the contacts are held in circuit closing position during a toasting operation.

ner set forth in my copending application Serial l speeds.

latch arm |85 which holds parts of the toaster intheir operative positions to cause energization of the heating elements and toasting of a slice of bread.

Referring now to Fig. 14 of the drawings I have there illustrated a modied form of detent |9| having a notc'hed cam surface |93 instead of a smooth surface as was shown in the other form thereof. Arm |59 may be provided with a relatively sharp-cornered pin |95 for engagement with one of the notches in the surface |93 thereby increasing the deniteness of engagement between pin |95 and the detent to cause releasing movement thereof. In all other respects the parts associated with the parts shown in Fig. 14 are the same as have already been hereinbefore described.

It will be noted that the device embodying my invention provides a new method of control of an automatic toaster to vary'the duration of an operating period of the toaster. A mechanical timer is operable at a relatively slow fixed speed for a major portion of the duration of a toasting operation and is then operable at a relatively higher fixed speed for the remainder of 'said duration thereby making available substantially all of the power of the spring for effecting release of mechanism or parts held in certain denite positions during a toasting period or for returning such parts to their normal positions. The instant of change-over from one speed to another is determined by a thermostat subject to toaster temperature thus distinguishing from a method in which a thermally-controlled variablespeed timer is-used. The device embodying my invention provides releasing means energized by the timer itself and a thermal control means responsive to toaster temperature for determining the absolute and the relative lengths of time of operation of the timer of the different speeds during an operating period.

It is obvious further that while I have described a two-speed timer I am not limited thereto, but by the application of the same principles can prov ide a plurality of different substantially fixed It is in this particular respect that the operation of my device distinguishes clearly from a variable speed timer such as is already well known in the art and which has been applied to electric automatic toasters of this general type.

While I have illustrated one form of latch-releasing lever arm |41 actuated by the timer, I do not desire to. be limited thereto, since the function of -this lever arm is to provide a power member driven by the timer and movable in a definite path to energize an actuating means for eecting release of a latch.

Another feature of the device herein disclosed and claimed is that the timer spring can unwind fully after each toasting operation and before theinitiation of the next following toasting operation. The resistance to be overcome by an operator when moving the actuating knob downwardly is not subject to a sudden increase as is the case where a mechanical timer is used, which operates' at a'iixed speed during the entire toasting operation, which toasting operation may be terminated before the spring has been fully unwound. v

Various modifications may be made in the 'device embodying my invention without departing from the spirit and scope thereof, and I desire therefore that only such limitation shall be placed thereon as' are imposed by the prior art or as set forth in the appended claims.

I claim as my invention:

1. In a timing mechanism for causing other mechanism to operate after a time interval, `a spring gear train, a retarding means including a balance wheel and a pivotally mounted piniony normally meshing with a gear of said gear train and operating said balance wheel, a 'detent for holding said pinion in mesh with said gear and means energized by thev spring for effecting movement of said detent and consequent disengaging movement of said pinion from said gear.

2. In a timing mechanism adapted to cause other mechanism'to operate after a time interval, a power driven gear train, a retarding means including a balance wheel and a pivotally mounted pinion normally meshing with a gear Vof said gear train and operating said balance wheel and thermally-controlled means moved by the timing mechanism for effecting pivotal movement of said pinion to disengage it from said gear.

3. In a timing mechanism adapt'ed to cause other mechanism to operate after a time interval, a spring drivenA gear train, a retarding means therefor including a balance Wheel actuable by a pivotally mounted pinion normally meshing with a gear of said gear train, a detent for holding said pinion in mesh with said gear, a lever arm actuable by the timing mechanism, means pivotally connected with the leverarm for engaging the detent to effect release thereof, and thermally-actuable means acting on said pivotally connected means for determining the time of release of said detent.

4. A timing mechanism as set forth in claim 3 and including a manually operable means to wind up said spring and cause simultaneous movement of said lever arm and movement of said pivotally mounted pinion into engagement with said gear wheel and into latching position. f

5. In a mechanical timer for mounting on an electrically heated automatic toaster having a bread slice support and a control switch springbiased respectively to non-toasting and to open positions and movable respectively to toasting and closed positions and detent means for holding the bread slice support in toasting position and the switch in closed position, said timer effecting release of said detent after a time interval and including a spring driven gear train, a retarding means normally connected with the gear train to cause said gear train to operate at a substantially xed relatively slow speed and thermally-actuable means subject to toaster temperature for effecting disengagement of said retarding meansfrom said gear tr'ain to effect operation of said gear train at a higher speed and application of substantially the full power of thel spring to effect .releaseof said detent.

6. A timer asset forth in claim 5 in which the retarding means is urged to disengaged position by said gear train and is moved to engaged position simultaneously with movement of the bread slice support to toasting position and the switch to closed position.

7. A timer as set forth in claim 5 and including a detent for holding said retarding means in engaging position and means energized and moved `by said spring to cause releasing movement of said detent.

8. In a timing mechanism adapted to cause other mechanism to operate after a time interval, a power driven gear, a retarding means to cause said gear to operate at a substantially fixed re1- atlvely low speed, saidl retarding means including a pivotally supported pinion normally in mesh with said gear, detent means to hold said pinion in mesh with said gear and thermallycontrolled power means energized by the timing mechanism to act on and'release said detent means to cause disengaging movement of said pinion from said gear to cause said gear to operate at a. relatively high speed.

9. In a timing mechanism adapted to cause other mechanism to operate after a time interval, a spring driven gear, a retarding means to cause said gear to operate at a relatively slow speed, said retarding means including a pivotally supported pinion normally in mesh'with said gear and a balance wheel having a iixed support,

means connecting the balance wheel to the pinion .to cause actuation of the balance wheel by the pinion, a detent'for holding said pinion in mesh with said gear and thermally-controlled means energized by the timing mechanism to engage and move said detent to eiect disengaging movement of 'said pinion from said gear to cause said gear to operate at a relatively high speed.

10. In a timing mechanism adapted to cause other mechanism to operate after a time interval, a power driven gear train including a swingably mounted retarding means to cause the gear train to operate at one substantially xed speed, a detent for normally 'holding said retarding means in proper operative position and thermally-controlled means actuated by the timing` mechanism for causing release of said detent and a disconnecting movement of the retarding means and operation of the rest of the gear train at a higher speed.

11. In a timing mechanism adapted to cause other mechanism to operate after a time interval, a power driven gear train, a retarding means including a balance wheel and a pivotally mounted pinion normally meshing with a gear of said train, a mechanical connection between said pinion and said balance wheel, means supporting said pinion for movement away from and toward said gear, means for holding said pinion-in mesh with said gear and thermally-responsive means acting on said holding means and incliiding a lever arm actuable by the timing mechanism for causing movement of said pinion to disengage it from said gear.

12. A device as set forth in claim 9 and including means to wind up said spring and cause movement of said pinion into mesh with said gear. y

13. In al timing mechanism adapted to cause other mechanism to operate after a time interval, a spring driven gear train, a retarding means therefore including a balance wheel, a xedly supported shaft on which ysaid balance wheel is mounted, a pivotally mountedl pinion normally meshing with a gear of said gear train, 'means connecting the pinion to said balance Wheel to actuate the latter, a detent for holding the pinion in mesh With said gear and having a cam surface, a lever arm supported solely by said timing mechanism and actuable thereby, means pivotally connected with the lever arm for engaging the cam surface of the detent to elect release thereof and thermally-actuable means supported solely by said timing mechanism and acting on said pivotally connected lmeans for determining the time of release of said detent.

14. A device' as set forth in claim 13and including a means to wind up the spring and cause simultaneous movement of the lever arm and movement of the pinion into mesh with said gear and into latching engagement' with said detent.

l5. In a timing mechanism for mounting on an velectrically heated automatic toaster to determine the duration of an operating period thereof, said timing mechanism including a spring driven gear train operable initially at a substantially xed relatively slow speed, a pivotally mounted pinion normally meshing with a gear of said gear train, a detent for holding the pinion in mesh with the gear of said gear train, a balan'cewheel, a shaft on which said balance wheel is mounted and having a fixed support, a connecting rod connecting the balance wheel and the pinion to cause oscillation of the balance wheel by the pinion and thermally-actuable means responsive to toaster temperature energized by said timing mechanism to cause release of said detent to cause disengaging movement of the pinion from the gear and operation of the gear at higher speed.

ROBERT SARDESON.