US2577004A - Timer mechanism - Google Patents

Description

R. C. DARNELL.

TIMER MECHANISM 5 Sheets-Sheet 1 Filed April 5, 1946 I INVENTOR.

R. C. DARNELL TIMER MECHANISM Dec. 4, 1951 5 Sheets-Sheet 2 Filed April 5, 1946 .INVENTOR.

Dec. 4, 195] c, DARNELL 2,577,004

TIMER MECHANISM Filed April 5, 1946 5 Sheets$heet 3 INVENTOR. F Fara-:22.

R. C. DARNELL TIMER MECHANISM Dec. 4, 195] 5 Sheets-Sheet 4 Filed April 5, 1946 INVENTOR. 76K Z, Jar/7652:

2% Mia.

Dec. 4, 1951 DARNELL 2,577,004

TIMER MECHANISM Filed April 5, 1946 5 Sheets-Sheet 5 d n I M 7 Y 7 a4 z INVEN Patented Dec. 4, 1951 Darnell,.Dexter', Mich.,v assigno'r to King-- Seeley' Corporation,- Ann Arbor, Mich., a corporation of Michigan Application April 5, 1946, Serial No. 659,764

19 Claims.

1. The present inventionrelat'es to a timer mechanism of the type utilized on stves,--wash-' ing machines and the like either for the purposeof sounding an audible signal after a: predeter mined timeintervalor actuating a-control Switch, or both.

Timers of the type to which the present invention relates are subject to severe usage in'that they are commonly used 'in placeswhichare-subject to dust; greas'e lad'en fumes-and other. foreignniatter which seriously interfere with the operation'of any form of clockmechanism. More'- over, th'ey'arecustomarily sold to manufacturers of stoves, washing machines andthe like andpermanentlymounted on such equipment by the purchaser, with the result that the manufacturer of the timing device has no control over the care with'Which-the timer ismountedl One consequence of this practice" isthat the timingmechanism is frequently distorted due to mounting strains tosuchan extent as to impair its operation.

Another distinguishing feature of-"su'ch timers is-the-fact' that the market for them demands a accuracy and close tolerances in the manufac tureof the various parts of the mechanism;

Accordingly, it is one object of the: present invention to provide an improved timer: of the type mentioned incorporating. means to prevent distortion of tl'ie; mechanism as:a result of mounting strains;

Another object. of: the invention: is to: provide a timer iILWhiChZall of the elements of. thetiming mechanism are sealed. against. dirt and;

foreign matter.

A further objectof. the invention is to provide a mechanism of the type mentioned incorporating novel features of construction to facilitate assembly of the timer and a preliminary. run-in of the timing. gear train in order to: eliminate defects and roughness inherent in the teeth of low cost punched gears Another. object of the invention is to provide a timer incorporatinga novel and simplified means to insure that the timer actuated signal or switch is. operated'when the main arbor of the timer is in the proper position with reference to the indicating dial thereof.

Another object of the invention is. to provide an improved. means for: stopping the: operation of the timer mechanism upon actuation of the signal or control switch.

Another object of the invention is: to provide ant-improved. and simplified means for prevent ing. operation of the timing mechanism when the setting knob is rotated to its maximum ex-- tent in a setting; direction in order to provide operation of the controlled equipment for an unlimited period.

Another object of the invention is to: provide animpi'oved stop'mechanism for the main arbor which will limit. rotation thereof in a setting: directionat the maximum set position and which at the. same time,.wi1l permit a full 360 rotation 01'' the arbor during. setting.

Another: object' of the invention is to provide a timer adaptedto be mounted: upon the" rear:

of a panel which carries the indicating dialand incorporate a signal bell having its closed end portion intermediate the panel and the timer mechanism, itself, thus leaving the rear wall of the timer casing free for mounting of" acontrolled switch.

Another object of the invention is to provide an improved arrangement and location of afriction clutch in a timer mechanism to permit" manual return of the main arbor without actu'a tion of the escapemechanism of the-timer.

Other objects and advantages of" the inve'ntion will become apparent" from the following specification, the drawings relating thereto and the claimshereinafter set forth.

In the drawings:

Figure" 1" is a side elevation of the improved timer mechanism showing the manner in which itis mounted upon a supporting panel;

Figure 2' is a front elevation of the timerwith' the supporting panel removed;

Figure 3 is a front elevation of the timer with the control knob and's'upporting panel removed;

Figure'4 is a front elevation of the timer with the control knob, the supporting panel and the" belli removed Figure 5 is a rear View of the timer with a" major portion of the rear casing removed to. show the mechanism carried on the rear side of the rear movement plate;

Figure dis a front view of the front movement plate;

Figure 7 is a sectional'view taken on the irregular section line 1-1- of Figure 6, which. section line passes through the axes of all of the gears in the. timing train;

Figure 8 is-a fragmentary view of the escapement mechanism taken on the line 8-8 of Figlire-'7;

on the line l2l2 of Figure 4;

Figure 13 is a view taken on the line of Figure 12;

Figure 14 is a View taken on the line l4l4 of Figure 12; and

Figure is a fragmentary view similar to Figure 14 with the ratchet mechanism removed to show the mounting of the mainspring.

Referring to the drawings, and particularly to Figures 1 to 7, the timer comprises a pair of movement plates l and 2 which are connected together in properly spaced position by means of three posts 3, 4 and 5 spaced around the periphery of the movement plates, as best shown in Figure 6. The movement plates are formed of relatively thin sheet brass, .so that they may be formed and at the same time provided with openings to journal the staffs of the timing gear train by a. punching operation. In order to avoid undue roughness of the walls of the bearing openings and .also avoid countersinking the bearing openings in order to obtain bearings of the requisite short length, the plates l and 2 must be made of relatively thin stock and, consequently, impart little strength or stiffness to the timing mechanism carried by them.

The timing mechanism, as best shown in Figures 6 and 7, comprises a main arbor 6 on which is freely journaled a main gear I which meshes with a pinion 8 fixed to a gear 9 on a staff 10. Gear 9 meshes with a pinion I l, which is frictionally connected to a gear l2 on staff [3 by means of a friction clutch 14 formed of a dished sheet of spring bronze provided with a plurality of circumferentially spaced peripheral notches 15. Gear E2, in turn, meshes with a pinion l6 fixed to gear I! on staff 18, and gear I? meshes with a pinion l9 fixed to an escape wheel on staff 2|.

' As best shown in Figure 8, the escape wheel 20 is provided with a plurality of escape teeth adapted to cooperate with a pair of pins 22 and 23 on the verge arm 24 of a verge type escapement mechanism. The verge arm 24 is fixed to a staff 25 and its opposite end is formed with a slot 26 and a pair of gears 27 and 28 adapted to co-operate, respectively, with a pin 29 and the cut-away staff 36 of a balance wheel 3|, in the usual manner. The staff 36 of the balance Wheel 3| is provided with a spiral balance spring 32 anchored on a bracket 33. The ends of the balance wheel staff 36 are tapered and fitted into conical bearings in a bearing insert 34 carried by movement plate I and an adjustable plug 35, which is threaded into a suitable opening in movement plate 2. All of the remainin staffs l6, l3, l8, 2! and 25 are provided with cylindrical end journals adapted to fit punched bearing openings in the movement plates I and 2;

j The mechanism so far described comprises a more or less conventional timing gear train and verge type escapement mechanism in which the main gear 1 will drive the gear train at a rate determined by the escapement mechanism. The only features not common in such timing mechaamooi nisms are the friction clutch l4 and its particular location in the timing gear train and the fact that the main gear i is not fixed to the arbor 6.

As best shown in Figures '7 and 15, the main gear I is connected to the arbor 6 by a ratchet mechanism comprising a toothed ratchet wheel 36 fixed to the arbor 6 and a pawl 3'! pivoted on the gear I by means of a pin 38. The pawl 31 is urged into engagement with the ratchet wheel 36 by means of a curved leaf spring 39, which is anchored at one end on a pin 40 carried by the gear! and which bears intermediate its ends on "a pin carried by the gear I. The arrangement of the pawl and ratchet is such that, when the control knob 41, which is carried by the projecting end 42 of the arbor 6, is rotated in a direction to set the timer and wind the mainspring 43, the ratchet wheel 36 will ratchet past the pawl 31 and thus effect no rotation of the main gear I Or any portion of the timing gear train connected thereto. This relieves the control knob of the force which would otherwise be required to slip the friction clutch l3 which connects pinion H to gear l2. 7

When it is desired to manually return the main arbor 6 in a direction which will unwind the mainspring 43, the ratchet mechanism engages and locks gear I to the arbor and the friction clutch l4 permits movement of the pinion II with respect to the then stationary gear l2. At this time the mainspring is assisting return movement of the arbor, rather than opposing it,

and, consequently, the force required at the knob 4| to slip the clutch i4 is negligible. This combination of friction clutch and ratchet mechanism permits the use of a heavier mainspring without correspondingly increasing the manual force required to set or adjust the set position of the timer. The heavier mainspring, in turn, insures a more positive driving of th timing mechanism, which might otherwise be insufiicient as the result of friction or defects in the mechanism due to manufacturing tolerances.

It will be observed that the friction clutch is located in the timing gear train at a point remote from the arbor 6 and, consequently, is located in a low torque region in the timing gear train. Thus, for example, if the gear ratio between each gear and pinion in the train is in the order of six to one, the torque applied to pinion I I will be one thirty-sixth of that exerted by the mainspring on the arbor 6; By locating the friction clutch in the low torque region, it is possible to use a clutch which exerts a very light pressure, even though a relatively strong mainspring is employed. This greatly assists in eliminating clutch chatter, which is induced when a wide divergence exists between the static and sliding friction of the clutch. The magnitude of this divergence is a function of the clutch pressure, increasing as the clutch pressure increases. Consequently, if the clutch is located on the main arbor, it must apply a much greater clutch pressure to prevent slippage incident to the force exerted by the mainspring, and this greater pressure, in turn, increases the divergence between the static and sliding friction and thereby induces chatter.

In order to prevent distortion of the relatively thin movement plates l and 2 and consequent impairment of the operation of the timing mechanism, the timer is provided with a relatively rigid mounting plate 44, which is so constructed and connected to the movement plates as to relieve the latter of .all mounting and opera ating strains. The mounting plate 44 is a relatively thick, rigid plate, preferably formed by die-casting in the manner best shown in Figures 4, 7, 12, 13 and 15..

Referring to Figure 4,. the mounting plate 44 is provided with three circumferentially elongated slots 45, 46 and 41 adapted to receive the threaded extremities of the three posts 3, 4 and 5, whichsupport and space the movement plates. The slots are elongated circumferentially inv order to permit a rotational. adjustment of the position of the mounting plate relative to the; movement plates, for a purpose hereinafter: described. The slots are of such size that they do not locate the mounting plate axially with respect to the movement plates, this axial locating function being. performed by an axially projecting flange 48 formed on the inner side of the mounting plate, as best shown in Figures 8, l2 and 15, which accurately fits within a relatively large circular opening 49 formed inthe movement plate I, as best shown in Figure 6. The opening 49 is accurately located with respect to the bearing openings for the staffs of the'gear train to insure proper axial positioning of the mounting plate.

By thus locating the mounting plate with reference to the movement plates by a centrally located flange and by simply clamping the mounting plate to one of the movement plates at three circumferentially spaced points, the movement plates are relieved of the. strains which would otherwise be incident to mounting of the timer on a supporting panel by a connection either directly to one of the movement plates or to the mounting plate posts 3, 4 and 5. To further relieve the movement plates of the strains incidentto manual operation of the control knob 4|, the front bearing for the main arbor 6 is provided by the mounting plate 44 at the point indicated by the numeral 50 in Figure 7. The. bearing opening 50 is sealed at its. outer end. by a felt seal, as bestshown in Figure 7. The rear end of the arbor, which. is subject to less load, is journaled in the movement plate 2, in. the usual manner.

The front face of the. mounting plate 44., as-

best shown in Figure 4,. is provided with four outwardly projecting bosses 5|, 52, 5'3 and 54,.

which project. from. the face. of the mounting plate to the same distance, andv it is also provided with two additional bosses. 5,5 and 56., which project. from the plate to a lesser distance.

Bosses 52 and 54 are provided with. tappedopenings to receive a pair of mounting screws. 51' and 58, by means of which the mounting plate and associated timer mechanism may be secured to a supporting. panel indicated at 59 in Figure 1. This panel may form a portion of the stove. or other piece of equipment on which the. timer is to be mounted, and will ordinarily carry the usual indicating dial which co-operates with the pointer on the. control knob 4|.

The remaining two larger bosses 5| and 53 merely act as abutmentswhich bear against the back side of the panel 59 to prevent tilting of the timer with reference to the panel.

As best shown in Figure '7, the smaller bosses 55 and 56 are provided with tapped openings to receive mounting screws 60 for a signal bell indicated generally at 61.

It will be. noted that by reason of the greater projection of. the bosses 5| through 54, the front surface of the closed end of the bell lies in a plane spaced rearwardly from the rear surface of the mounting panel 59. Suitable openings are provided" in the closed end of the bell' to permit projection of the bosses- St to 54 and also the main arbor 6.- The skirt of the bell surrounds the the mounting plate 44' also serves as a housing for the mainspring 4:3,. as best shown in Figures 7, l2

and; 15.. As there indicated, the rear face of the mounting plate is provided with a cylindrical recess 6-7. coaxial with the locating flange 48 and the mainspring 43 is positioned within that recess. two. points spaced. from each other, the inner face of the mounting plate is provided with a. pair of recesses 63 and 54, which are the. same depth as the spring recess 62 and which are con-- nected to. it by communicating radial slots through the. locating flange 48. and the outer wall of the recess 62.. The outer end 55 of the mainspring 43 is bent into a U-shape, as: best shown in Figure 15, so that it. may pass outwardly through the. connecting radial. slotv into one ofv the recesses. 63 or' 64 and engage the inner wall thereof, thus locking the mainspring against rotation with respect to the mounting. plate. Two recesses 63 and 64 are provided so that the spring tension may be adjusted to. compensate for vari ations. in the stiffness of the spring.

The inner end of the mainspring, in its free state, spirals inwardly into contact with the arbor 6 in the manner best shown in Figure 15. At.

the point of contact, the spring is provided with a. slot 56 adapted to receive a projecting lug 57 formed on the arbor 5. The arrangement is such that after the mainspring is inserted within the recess of the mounting. plate, the arbor may be assembled on the mounting plate by simply 111- serting the. end 42' of the arbor. through the opening 50' of: the mounting plate, with the lug 61 in a: position. spaced angularly' with respect to the slot. 66. Thereupon, the lug may be engaged inthe slot 66 by rotating the arbor counterclockwise, as viewed in Figure 15.

By a. reverse operation, the arbor may be disassembled with respect: to the mounting plate and mainspring. This arrangement facilitates a preferred and simplified method of assembly and.

also a. preliminary run-in of the gear train priorto. complete. assembly; Thus, it is preferred to assemble the movement plates l' and 2 and all of the shafts journaled in them except. the balance staff 30 and the main arbor 5. The balance staff is then separately assembled with the. main gear T and. the ratchet mechanism. If it is desired to run-in the gear train, the separately assembled; arbor and main gear and ratchet are inserted in a fixture which will engage and rotate the end 42 of the arbor. A selected movement plate assemblyis then installed on the fixture and located axiallywith respect to thearbor by means which engagethe opening 49 in movement plate I in the same manner that that opening is engaged by the-flange 48 of the mounting plate in the finally assembled mechanism.

The verge arm 24' is swung entirely out of engagement with the escape wheel 20, so that it will no longer interfere with free rotation of the gear train. This is accomplished after assembly of the verge arm and escape wheel by providing a.

radially extending slot 61a in the escape wheel which deep enough to permit entry of one of gov-7,0041

7\ the pins'22 or 23 to the extent necessary to effect a swinging of the verge arm through an angle slightly in excess of 90, as is required to effect complete disengagement. The gear train may.

then be run-in by the previously described run-m fixture and thus effect a polishing or working of the tooth surfaces, which will facilitate easy running of the mechanism. After the run-in period is completed, the movement plates are removed from the fixture, the verge arm restored to normal position and the balance .stafi 30 installed by manipulation of the adjustable plug 35 without disturbing the spacing of the movement plates. Themain arbor, gear and ratchet assembly is theninserted into a mounting plate and mainspring assembly, in the manner previously indicated, and the mounting plate, together with the mainspring, the arbor and the main gear, are then assembled on the movement plates, the

opening 49 in movement plate I' being of sum! cient size to permit insertion of the main gear I. The mounting plate may then be secured to the posts 3, 4 and 5 to complete the assembly of the timing mechanism proper.

' The mechanism of the timer which operates a signal or a controlled switch is best shown in Figures 5, 6, 8, and 11. This mechanism comprises a shaft 68 which is journaled in the movement plates l and 2 and has fixed thereto a bell crank lever, indicated generally at 69, provided with a pair of arms 10 and 1 I. Arm 19 is provided at its extremity with a stub shaft 12 carrying a roller I3, which is normally urged inwardly toward the arbor by means of a spring 14, shown best in Figure 6. The bell crank is positioned between the movement plates but the pin 12 projects through an arcuate slot 15 in movement plate 2 and the roller 13 is located rearwardly of the latter movement plate in position to co-operate with a cocking and tripping mechanism, shown best in Figures 5 and '7.

As there shown, the cocking and tripping mechanism comprises a generally circular disc 16, which is fixed to the rearwardly projecting end of the arbor 6 and which carries a pivotally mounted tripping element 11, the tripping element being pivoted on' a pin 18 carried by the disc 16. The disc 16 is provided at one point in its periphery with a notch 19 which, as best indicated in dotted lines in Figure 5, has a substantially radial wall 80 at one side and a sloping wall Bl at the other which is adapted to operate as a cam to lift roller 13 and thereby swing the bell crank lever 69 in a clockwise direction, as viewed in Figure 10. The tripping element 11 overlies the notched portion of the disc 16 and is, itself, provided with a notch 82, the bottom of which is normally located at the same point as the bottom of notch 19 in disc 16. However,

the notch 82 in the tripping element 11 has a substantially radial side 83 corresponding to the sloping side 8| of the notch in disc 16.

, A spring wire 84, having one end fixed to the disc '16 at 85 and the opposite end connected to the tripping element 11, normally acts to urge the tripping element in a counterclockwise direction, as viewed in Figure 5, until a forwardly bent flange 86 on the tripping element engages I the side edge 80 of the notch in disc 16. The arrangement is such that when the control knob 41 is rotated in a clockwise direction, as viewed in Figure 2, the arbor 6 and disc 16 will rotate in a counterclockwise direction, as viewed in Figure 5, thus causing the roller 13 to be cammed upwardly along vthe sloping wall 8! until the roller rests upon the outerperiphery of the dise During this cocking operation, the tripping element Tl pivots about the pin 78 in a clockwise direction to withdraw the wall 83 of notch 82 out of the path of the roller 13. As soon as the roller reaches the peripheral surface of the disc 16, spring 84 returns the tripping element ll to the position shown in Figure 5. Consequently, when the mainspring, under control of the escapement mechanism, slowly returns the arbor in a counterclockwise direction, as viewed in Figure 2, the disc 76 will travel in a clockwise direction, as viewed in Figure 5, and the roller 13 will eventually drop over the sharp shoulder formed by the junction of the wall 83 and the outer periphery of the tripping element 71, thus effecting a sudden tripping of the bell crank lever 69 under the influence of spring 14. This sudden tripping of the bell crank lever 69 gives a sharp rotation of the shaft 68, which may be employed to actuate either a bell hammer or a control switch, or both.

As best shown in Figures 5 and 7, the rear wall of the timer is enclosed by means of a cupshaped casing 8?, the forward edge of which telescopes into a peripheral notch 88 formed in the mounting plate 4. A sealing gasket 89 is positioned between the movement plate l and the periphery of the mounting plate 44 and overlaps the joint between the housing 81 and the movement plate to form a completely sealed enclosure for the timer. The housing 81 is secured in position by means of nuts 90 threaded onto the extremities of the posts 3, t and 5, previously mentioned. The shaft 68 projects through an opening 9| formed in the housing 3'! and at its outer or rear end has fixed thereto an actuating lever 92, as best shown in Figures 5 and '7.

To seal the opening 9! about the shaft 68, there is provided a felt washer 93, which is held in position by a sleeve 94 that is clamped between the washer and the actuating lever 92. The shaft 68 is provided outwardly of the lever 92 with a reduced cylindrical portion 95, upon which is journaled a bell hammer 96; A spring washer 91 is positioned between the lever 92 and the bell hammer 96 to take up clearance between the lever and bell hammer, and a securing nut 98 is threaded on the end of shaft 68.

As best shown in Figure 5, the bell hammer is provided with a hammer weight 99, which is secured thereto by welding or otherwise. It may be located in proper position prior to welding by means of a pair of bent-up tongues Ito and I9! formed on the lever 96. The hammer lever has a lost motion connection to the actuating lever 92 by reason of a pair of bent-up tongues I92 and IE3 formed on the actuating lever 92 which act to limit relative movement between the two levers. A spring wire [04 encircles the spring washer 9! and has its ends connected, respectively, to the levers 92 and 96, as best indicated in dotted lines in Figure 5. The spring liltiacts normally to hold the hammer levers against the bent-up tongue or stop IE2. However, when the lever 69 is tripped by the tripping mechanism, the actuating lever 92 makes a sharp sudden, movement in clockwise direction, as viewed in Figure 5, thus throwing the hammer lever away from the stop I92 and causing the hammer to. strike the skirt of the bell 61 to sound a signal.

' It will be apparent that, if desired, the lever 92 may also be formed to actuate an electric switch for control purposes inlieu of or at the same time as it efiects a ringingof the bell. In view of the -fact that the bell is mounted at the front of the timer, the back casing 8? is unobstructed and hence maybe used to mount such a switch, in the manner shown in greater detail in the application of Glenn Morse on Timing Mechanism, Serial No. 611,115, filed August 17, 1945, now Patent No. 2,480,760, dated August 30, 1949.

.An important feature of the invention resides in the utilization of the bell crank lever 59 to perform three additional functions; namely, to mechanically limit rotation of the arbor 6 in a setting direction beyond a full setting position which is displaced approximately 360 from the zero position, to prevent operation of the escapemen-t mechanism and consequent unwinding of the clock spring when the arbor is rotated in a setting direction to the maximum extent; and to prevent operation of the escapemen't mechanism after the arbor is returned to zero position and the bell or controlled switch is actuated.

The mechanical stopping of the arbor at a full wind position is achieved by impartin to the lever '69 an additional increment of counterclockwise rotation, as viewed in Figure 5, at the end of the .setting rotation of the arbor 6. As best shown in Figure 5, when the arbor 6 and cooking disc T6 are rotated in a counterclockwise direction, as required to set the timer, the roller '13 on arm 10 of the bell crank 69 is cammed upwardly to the periphery :of the disc T6. Thereafter, as the counterclockwise rotation of the disc 7'6 continues, the roller 13 will ride on the periphery of the disc until it engages the outwardly projecting lug 15 formed on the tripping element T1 to the sequent counterclockwise rotation of the disc '16 will cause the tripping element H to rotate in a clockwise direction about its pivot pin '18 by reason of the engagement of the tripping element with the roller 13. During such rotation of the tripping element, the roller 13 will roll down the left-hand edge of the lug "35 until it seats within a recess [56.

Thereafter, as the rotation of the dics 1'6 continues, the tripping element Ti will elevate the roller to a position out of contact with the periphery of the disc 1 6, thus imparting an additional increment of counterclockwise rotation to the bell crank lever 69. This additional .rotation of the bell crank lever swings the arm I! of the lever to the right, as viewed in Figure 5, until a rearwardly projecting flange It! on the arm H moves into the path of movement of a forwardly projecting lug i 38 formed on the cocking disc 16. IE9 is formed in the rear movemnt plate 2 in order to permit the fiange It)? to project into the path of the lug )8.

One advantage of this form of mechanical stopping mechanism is that, unlike ordinary fixed abutment stops, it permits rotation of the arbor through an angle of 360 or more before it becomes effective. In the particular embodiment illustrated, as will be apparent from Figure 5, the arbor may be rotated slightly in excess of 360 before the lug I68 returns to a position in which it will engage the flange I67 on lever H to positively stop further setting rotation of the arbor.

In order to prevent operation of the clock mechanism when the arbor is rotated to full wind position, means are provided responsive to the additional increment of movement of the bell crank lever 59 for interfering with the operation of the escapement mechanism. This means is best shown in Figures 6, 8, 9, l and 11. This left of the notch therein. Sub- For this purpose, an arcuate slot means comprises a relatively thin flexible wire H4 having one end fixed to the shaft 68 by crimping it between a pair of discs H. and H2 which are fixed to the shaft. The free end of the spring I I4 is bent forwardly at l I 3 and is adapted to engage and interfere with the operation of the verge arm 24. Figure 8 shows the parts in the position they occupy when the hammer is cooked and the timer is running, in which position the wire I I4 is out of contact with the verge arm.

However, when the bell crank lever 69 is given its additional increment of movement at the full setting position, the wire H4 will be swung in a position shown in Figure 10, where it engages the free end of the verge arm 24 and prevents operation thereof.

The provision of the above described means to prevent operation of the clock mechanism when the arbor is rotated to the full wind or full setting position is particularly useful when the timer is utilized to control a start and stop switch for a piece of apparatus. In that case, cocking of the lever 69 may close the starting switch and tripping of the lever at the end of the timing cycle will open the switch. However, where continuous operation is desired, the arbor may be rotated through a full winding movement, whereupon the wire I M will interfere with the clock mechanism and prevent unwinding. As a result, the controlled switch will be held closed indefinitely. When it is desired to disengage the holding mechanism, it is only necessary to manually rotate the arbor 6 through a very small angle sufficient to disengage the wire il from the end of the verge arm. The full timing cycle may then take place or, if desired, the arbor may be rotated to the zero position to stop the controlled apparatus.

It is desirable, in timers of the type to which the present invention relates, to insure that at the end of a timing cycle the manually operated knob and pointer will stop at the zero position on the indicating dial. In the past, it has been proposed to accomplish that result by having a member carried by the arbor engage an abutment on the movement plate at the end of .its return rotation and by locating the movement plates in a fixed rotative position with respect to the dial panel. Due to unavoidable tolerances in the manufacture, this prior expedient does not accurately terminate the unwinding movement of the mechanism with respect to the zero on the indicating dial. Moreover, in order to avoid stopping the mechanism before the signal actuating lever is tripped, it is necessary to allow for a slight additional unwinding rotation of the arbor after the actuating lever is tripped. This introduces an additional variation in the final position of the indicating knob.

In accordance with the present invention, these defects are overcome by providing a Zero stop mechanism associated with the actuating lever and effective to stop the timing mechanism when the lever is tripped, in combination with a rotative adjustment of the mounting plate with reference to the movement plates. Thus, as best shown in Figures 9 and 10, the shaft 68 of the bell crank lever 69 is also provided with a slender resilient wire Ill) similar in construction to the previously described wire H4 and likewise clamped between the discs H! and H2 in the manner shown in Figure 11. The arrangement and position of the wire Hi] are such that when the bell crank lever 69 is tripped incident to dropping of the roller 13 into the notch in the fectively stops the unwinding movement of the timing mechanism at exactly the point at which the bell or switch is actuated and thus prevents further movement of the controlled knob and pointer 4|. It will be observed that this stop mechanism is not actuated when the arbor is me. fixed rotative position with respect to the movement plates because of the unavoidable tolerances in the manufacture of the various elements of the mechanism'but that it does positively fix the stopping operation at the time the actuating lever is tripped, regardless of variations in the dimensions of the parts.

In order to insure that the signal or switch will be tripped and the timing mechanism stopped when the control knob 4| is in the proper position wth respect to the indicating dial, the previously described mounting plate 44 is adjusted angularly about the arbor 6 until the arbor is in a fixed rotative position with respect to the mounting plate 44 when the bell crank lever 69 is tripped. This adjustment is permitted by the elongated slots 45, 46 and 41, which receive the threaded extremities of the posts 3, 4 and 5. To facilitate such adjustment, the mounting plate, adjacent its periphery, is provided with a plurality of equally spaced scribe marks H5, shown in Figure 4, adapted to co-operate with a knobwhich may be fitted on the end of the ar bor B.

By observing the position of the pointer on the knob 4| with respect to the scribe marks [5 V at the time that the lever 69 is tripped, the workman who is assembling the timer may make an appropriate adjustment of the rotative position of the mounting plate with reference to the movement plates. Since the mounting plate is held in fixed position with respect to the supporting panel 59 which carries the indicating dial, this adjustment will be sufficient to insure that the pointer will be on the zero point of the dial when the lever 69 is tripped.

An important feature of the-zero stop spring I I0 resides in the fact that it provides a starting impulse for the escapement. This is important in connection with a verge type escanement mechanism since with that ty e a relatively high torque is required to start the timing train when the verge arm is in dead center position, as compared with the torque required to keep the timing train in motion once it is started.

In that connection, it should be noted that in Figure 6 the spring H0 engages the outer side of the projection 28 on the verge arm, whereas in Figure 9 it engages the inner side of the projection 28. These two conditions illustrate two possible forms of interfering engagement which may result, depending upon the position of the 'verge arm when the wire H0 is swung into the position shown in Figures 6 and 9. If the free end verge arm is swung to the left of its dead center position, as viewed in Figure 6, the wire HI will pass the free end of the verge arm, as

shown in Figure 6, and the arm will, on its return swinging movement, engage the wire in the manner there illustrated. This engagement prevents the arm from completing its clockwise swinging movement and, consequently, stops the clock mechanism. If, on the other hand, the verge arm is in the position shown in Figure 9 when the wire |||l moves to its interfering position, the

wire will engage the inner side of the projection 28 in the position shown in that figure. The wire will thus prevent counterclockwise return of the verge arm and thereby effect a stoppage of the clock mechanism.

If wire I ll! engages the verge arm in the manner indicated in Figure 6, it will give the verge arm a starting impulse when it is swung from the stop position of Figure 6 to the running position of Figure 8. If the wire H9 engages the verge arm in the manner indicated in Figure 9, it holds the verge arm in position substantially offset from its dead center position, thus loading the balance spring. As a result, the loaded balance spring will start the verge arm movement as soon as the wire Ill] is moved out of engagement with the projection 28.

The particular stop mechanisms described above are peculiarly advantageous because, by utilizing the light resilient springs H0 and H4 engageable with a portion of the timing mechanism remote from the mainspring, the timing mechanism can be stopped by application of an exceedingly light force and strains on the mechanism thus avoided.

It will be observed that there is provided in accordance with the present invention a timer of improved design and construction peculiarly adapted for low cost mass production manufacture without sacrifice of reliability or accuracy. The relatively rigid and heavy mounting plate relieves the more delicate timing mechanism of mounting strains and the possible heavy stresses incident to manual operation of the knob 4|; the mounting plate, in conjunction with the rear casing, provides a sealed enclosure for all of the bearings of the timing train and thus protects the timing mechanism from dust, dirt and foreign material and retains lubricant; and the mounting plate, in conjunction with the zero stop mechanism, provides a simple and accurate means for positively fixing a stop position of the timer with respect to the zero point on the indicating dial. Thus the mounting plate, either alone or in conjunction with other features of the mechanism, greatly improves the quality and reliability of the mechanism.

While only one form of the invention is shown and described herein, it is apparent that others are available within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a timer, a main arbor, means for manually rotating the arbor in one direction from an actuating position for setting purposes, timing mechanism for returning said arbor to said actu ating position, means for limiting rotation of the arbor in said one direction while permitting rotation through an angle of 'at least three hundred sixty degrees, and means including a slender flexible wire movable in response to a predetermined rotation of said arbor in said one direction into interfering engagement with an element or said timing mechanism for preventing operation thereof, and a friction drive connection between the arbor and the escapement mechanism for permitting manual return movement of the arbor from said predetermined position.

2. In a timer, a main arbor, means for manually rotating the arbor in one direction from an actuating position for setting purposes, timing mechanism for returning said arbor to said actuating position, means for limiting rotation of the arbor in said one direction, an operating element, resilient means normally urging said element in one direction, means driven by the arbor for movement plates, a main arbor connected to said.

gear train, and a mounting plate of substantially greater thickness and rigidity than said movement plates and fixed thereto at the outer side of and in spaced relation to one of said movement plates, said mounting plate having a recess onv its inner side surrounding said main arbor, and a mainspring in said recess and having one end connected to the mounting plate and the other connected to the arbor.

4. A timer adapted to be fixed to a supporting I panel, said timer including -a pair of relatively thin movement plates, an escapem'ent mechanism, a train of timing gears journaled in said movement plates, a main arbor connected to-said gear train, and a mounting plate of substantially greater thickness and rigidity than said movement p-latesand fixed thereto at the outer side of and spaced relation to one of said movement plates, said mounting plate having a recess on its inner side surrounding said main arbor, and a main spring in said recess and having one end connected to the mounting plate and the other i end detachably connected to the arbor.

'5. A timer including a main arbor, a pair of movement plates, a timing mechanism carried by the movement plates and adapted to control the rate of rotation of the arbor, an external plate secured to said movement plates and having a a generally cylindrical recess on its inner side surrounding the arbor and provided with a plurality of radial openings, a spiral mainspring fitted in said recess and connected to the arbor at its inner end, the mainspring having an outwardly directed terminal portion at its other end adapted to enter any one of said recesses.

6. A timer comprising a timing mechanism having a main arbor, a casing enclosing said timing mechanism and providing a bearing for said arbor with the arbor projecting from, the casing, a movable actuator controlled by the clock mechanism and projecting through a closely fitting opening in said casing, means mounted on the exterior of said casing and adapted for operation by said actuator, said casing being otherwise entirely closed to seal the timing mechanism against dust and foreign material.

7. A timer including a pair of movement plates, a train of timing gears journaled in said move ment plates, a main arbor, a main gear on said arbor and connected to said gear'train, an external mounting plate fixed to and alongside one of said movement plates and having a bearing opening for said arbor, said one movement plate having an opening therein of sufficient size to permit insertion or withdrawal of said main gear with the arbor.

A timer including a pair of movement plates, a train of timing gears journaled in said movement plates, a main arbor, a main gear on said arbor and connected to said gear train, an exter- ,nal mounting plate fixed to and alongside one of said movementplates and having a bearing open- .ing for said arbor, a spiralmainspring having its outer end connected to themounting plate :andits inner end connected to the arbor, said one movement plate .havingan opening therein of sufficient size to permit insertion or withdrawal :of :said main. gear with the arbor and mainspring :as -:a unit-without disturbing the movement plates.

.9. A timer adapted for mounting on the back of a panel which-carries the timer dial, said timer com-prising a casing, a timing mechanism in said casing including a main arbor projecting therefrom and adapted to project through the timer supporting panel, .a bell overlying the front face of the casing and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said clock mechanism and adapted to strike the skirt of the bell, the bell having openings opposite the front face of the timer, and means on the casing and projecting through said bell openings for attaching said casing to the sup-porting panel.

10. A timer adapted for mounting on the "back of a panel which carries the timer dial, said timer comprising a, casing, a timing mechanism in said casing including a main arbor projecting therefrom and adapted to project through the timer supporting panel, a bell fixed to the front face of the casing and having a skirt projecting rearwardly and surrounding the casing, a rotatable shaft journaled in said casing and projecting through the rear wall thereof, resilient .means tending to rotate said shaft in one direction, means for rotating said shaft in the opposite direction to a cooked position, means under control of said timing mechanism for tripping said shaft, a hammer connected to the shaft and adapted to strike the skirt of the bell, and means on the casing and projecting through said bell openings for attaching said casing to the supporting panel.

11. A timer comprising a mainspring, an arbor connected thereto, an escapement mechanism, a train or gears connecting the escapement mech anism to the arbor, said arbor being rotatable in one direction manually to wind the mainspring and set the timer and being returnable by the main-spring under the influence of the escapement mechanism, and a friction clutch in said train of gears at a point remote from the arbor for permitting manual return of the arbor.

12. ,A timer comprising a mainspring, an arbor connected thereto, an escapement mechanism, a train of gears connecting the escapement mechanism to the arbor, said arbor being rotatable in one direction manually to wind the-mainspring and set the timer and being returnable by the mainspring under the influence of the escapement mechanism, a friction clutch in said train of gears at a point remote from the arbor for permitting manual return of the arbor, and a pawl and ratchet connection between the arbor and the train of gears for permitting setting rotation of the arbor to wind the spring without slipping the clutch.

13. A cooking and tripping mechanism for a spring actuated element comprising a rotatable shaft, a disc fixed to the shaft, an element movable in a plane parallel to the disc and having means adopted to engage the periphery of the disc, a spring connected to the element and urging said means against the periphery of the disc, a notch in the periphery of said disc adapted to receive said means on inward movement of the means under the infiuence of the spring,

one side of said notch being so inclined as to act as a cocking cam surface for camming said means out of the notch when the disc is rotated in one direction, a tripping element pivoted to said disc eccentrically with respect to said shaft and having a notch therein, the bottom of which in one position of said tripping element coincides with the bottom of the notch in the disc, resilient means normally urging said tripping element into said one position, the side of the notch in the tripping element which corresponds 'to said cam side of the notch in the disc being said disc adapted to receive said means on inward movement of the means under the influence of the spring, one side of said notch being so inclined as to act as a cooking cam surface for camming said means out of the notch when the disc is rotated in one direction, a tripping element pivoted to said disc eccentrically with respect to said shaft and having a notch therein, the bottom of which in one position of said tripping element coincides with the bottom of the notch in the disc, resilient means normally urging said tripping element into said one position, the side of the notch in the tripping element which corresponds to said cam side of the notch in the disc being substantially radial with respect to the disc to effect a quick tripping of said first mentioned element on reverse rotation of the disc, the opposite side of the notch in the tripping element projecting outwardly beyond the periphery of the disc in position to engage said first mentioned means after the disc has completed a rotation through a-predetermined angle in cooking direction, said tripping element being swingable about its pivotal connection to the disc in response to said last mentioned engagement, means on said tripping element adapted to lift said first mentioned means 01f the disc in response to said swinging movement, and means operable in response to the lifting of said first mentioned means off the disc for stopping operation of said clock mechanism and thereby preventing return of the disc to tripping position.

15. A timer adapted for mounting on the back of a panel which carriesthe timer dial, said timer comprising a casing, a timing mechanism in said casing including a main arbor projecting therefrom and adapted to projecting through the timer supporting panel, a bell fixed to the front face of the casing and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said clock mechanism and adapted to strike the skirt of the bell, the bell having an opening opposite the front face of the timer, means on the casing projecting through said opening and adapted to abut against the mounting panel for the purpose of locating the timer in spaced relation to the panel, and fastening means adapted to extend through the panel and said bell opening for securing the timer to said panel.

of a'panel which carries the timer dial, said timer comprising a casing, a timing mechanism in said casing including a main arbor projecting therefrom and adapted to project through the timer supporting panel, a bell overlying the front face of the casing and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said clock mechanism and adapted to strike the skirt of the bell, the bell having a central opening opposite the front face of the timer through which said arbor projects freely and having a pair of openings located on opposite sides of said central opening, and means on said casing projecting through said pair of openings and adapted to engage the mounting panel for the purpose of locating the timer with respect to the panel.

17. A timer adapted for mounting on the back of a panel which carries a timer dial, said timer comprising a casing, a pair of relatively thin movement plates located within said casing, a train of timing gears journaled in said movement plates, a main arbor connected to said gear train and adapted to project through said timer supporting panel, a mounting plate of greater rigidity than said movement plates and fixed with respect thereto at the outer side of and in spaced relation to one of said movement plates, a bell fixed to the front face of said mounting plate and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said timing gears and adapted to strike the skirt of the bell, the bell having openings opposite the front face of the timer, and means on the mounting plate and projecting through said bell openings for attaching said timer to the supporting panel.

18. A timer adapted for mounting on the back of a panel which carries a timer dial, said timer comprising a casing, a pair of relatively thin movement plates located within said casing, a train of timing gears journaled in said movement plates, a main arbor connected to said gear train and adapted to project through said timer supporting panel, a mounting plate of greater rigidity than said movement plates and fixed with respect thereto at the outer side of and in spaced relation to one of said movement plates, a bell fixed to the front face of said mounting plate and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said timing gears and adapted to strike the skirt-of the bell, the bell having an opening opposite the front face of the timer, means on the mounting plate projecting through said opening and adapted to abut against the mounting panel for the purpose of locating the timer in spaced relation to the panel, and fastening means adapted to extend through the panel and said bell opening for securing the timer to said panel.

19. A timer adapted for mounting on the back of a panel which carries a timer dial, said timer comprising a casing, a pair of relatively thin movement plates located within said casing, a train of timing gears journaled in said movement plates, 2, main arbor connected to said gear train and adapted to project through said timer supporting panel, a mounting plate of greater rigidity than said movement plates and fixed with respect thereto at the outer side of and in spaced relation to one of said movement plates, a bell fixed to the front face of said mounting plate and having a skirt projecting rearwardly and surrounding the casing, a bell hammer controlled by said timing gears and adapted to strike the skirt of the bell, the bell having a central opening opposite the front face of the timer through which said arbor projects freely and having a pair of openings located on opposite sides of said central opening, and means on said mounting plate projecting through said pair of openings and adapted to abut against the mounting panel for the purpose of locating the timer with respect to the panel.

' REX C. DARNELL.

REFERENCES CITED The following references are of record in the file of this patent:

Number 18 UNITED STATES PATENTS Name Date Emerson Oct. 10. 1905 Schaumberg July 22, 1913 Ruiz July 5, 1932 Metzler Mar. 19, 1935 Johnson Dec. 24, 1935 Lux Apr. 5, 1938 Rhodes Mar. 19, 1940 Rhodes Mar. 3, 1942 Lux Aug. 11, 1942 Godley Nov. 25, 1947 Morse Aug. 30, 1949

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