US2620872A

US2620872A - Expanded scale timer

Info

Publication number: US2620872A
Application number: US306420A
Authority: US
Inventors: Howard A Wyman
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1952-08-26
Filing date: 1952-08-26
Publication date: 1952-12-09
Anticipated expiration: 1969-12-09

Description

9, 1952 H. A. WYMAN EXPANDED SCALE TIMER Filed Aug. 26, 1952 v m e rm n o r bw m A t vdQ m. a E W M 0 H? 7 b a 1 #6 w. P a

2 AW 3 W f Patented Dec. 9, 1952 EXPANDED SCALE TIMER Howard A. Wyman, Framingham, Mass., assignor to GeneralElectric Company, a corporation of New York Application August 26, 1952, Serial No. 306,420

(01. ISL-15) 6 Claims. I

My invention relates to an expanded scale timer 'and'in particular-to a variable ratio drive between the constant speed timer motor and the time-indicator for the purpose of expanding thegraduations'at the low'end of the time scale. 'If the timegraduations at the lower portion of the scale'are'suitably expanded as compared to thoseatthe upper portion of the scale, the same percentage of accuracy in setting is possible at all'parts of'the scale. By means of my invention a selected and substantial degree of scale expansion 'is made possible, using a relatively simple, reliable mechanism.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention reference is made in the following description to the accompanying drawing in which:

Fig. 1 is a perspective, exploded, and somewhat diagrammatic view of the essential parts of an expanded scale timer embodying my invention;

Fig. 2 is an enlarged face view of an existing mechanism embodying my invention, with portions of the dial broken away; and,

Fig. 3 shows another expanded scale made possible by the use of my invention.

In Fig. 1 there is represented a timer motor having field laminations 3, an energizing coil 4, and a rotor and gear reduction chamber 5. This motor will preferably be a self-starting synchronous motor provided with a magnetic vibrator 5. The resilient magnetic vibrator provides a shunt path for a'portion of the stator flux of the motor and. will vibrate under the influence of the alternating flux of the motor when the latter is energized, unless the vibrator 6 is restrained from vibration. The shunt magnetic circuit through vibrator 6 is not fully shown in Fig. 1. However, the magnetic post I is magnetically connected with the statorfi at the left end of coil 4, and the vibrator arm 6 is magnetically connected with the stator through a magnetic plate 8 and a magnetic post fl at the right end of the coil 4 (see Fig. .2). Arm 6 has its free left end normally spaced from post 1 so as to be attracted thereto,

when vfree to do so, in synchronism with the motor flux pulsations, thereby causing a buzzing audible signal. As will be explained, vibrator arm .6 is normally .held away from post I to prevent such vibratoraction and sound, by the periphery of .a cam and cam follower plate In pivoted on a post- I.I except at the end of the time periodfor which the timer is set. Atsuch time adepression I2 in the cam periphery of plate I comes opposite the projection I3-and allows arm 6 to vibrate.

In the off position of the parts shown in Fig. l a rise I4 in the cam periphery of plate I0 is opposite projection I3 and prevents vibration of arm -6. Also in this position of the parts the motor terminal gear I5 is disconnected from a gear it through which the-timer is driven. Gear I6 is on a shaft I! with a pinion gear I8 but there is a friction clutch I9 between gear I6 and shaft I! to permit setting of the timer when-the gears are in mesh. Gear I8 meshes with a gear 20 when the timer is in operation but when in'the off condition shown in Fig. 1, gears I 3 and 20 are out of mesh.

The large gear 2|] is fastened on a shaft 2 I extending forward to'the front of the timer where it is provided with a manual timer setting knob 22. Having a bearing on shaft 2| is a hollow shaft 23 on which is fastened a pinion gear 24 meshing with 'a gear sector 25 in the plate I0. Hollow shaft 23 also carries a pointer 26 which indicates on the expanded time scale 21 at the front of the timer.

While it is unnecessary that shafts -2I and 23 have the same axis of rotation this is desirable from the point of view of a compact and neat assembly.

The front faceof gear 20 is provided with a multiple-turn spiral cam 20 This may be a groove or a ridge. A cam follower pin 28 projecting from the rear faceof plate It] which extends adjacent the cam bears against the spiral cam. It is now seen that when gear 29 is rotated either by the timing motor through gear I 8 or by turning shaft 2| by knob 22, the pin 28 in plate I1] is caused to follow in the cam 20 the pin moving approximately radially towards the axis of rotation of gear 28 as the gear is turned in a clockwise direction, and the pin 28 moving away from the axis of rotation of gear 20 when the latter is turned in a counterclockwise direction. 'This swings plate I!) about post II as 'a pivot, and the movement turns pinion 24 through gear sector 25 and also the hollow shaft 23 and pointer 26.

The gear and variable ratio cam drive between the motor and pointer 25 in the example given is such that the dial may be calibrated from 1 to minutes over an arc of about 300 degrees. leaving about 60 degrees space to provide for an alarmperiod followedby shutoff.

The scale expansion characteristics aredeter mined by the radial slope variation of the cam 20 and that part of the cam from the inner end to the radial offset point at 23 corresponds to the movement of the pointer 26 over the time scale from O to 60 on dial 2?. It is to be noted that over the lower about -minute portion of the scale where greatest expansion is desired, the radial slope of the cam is the greatest. For the upper portion of the scale the radial slope of the cam slot decreases, or it becomes more nearly concentric with the axis of rotation of wheel 23. About three turns of the spiral cam slot are here allotted for scale expansion characteristics. The portion of the cam slot from the offset 29 to the offset is approximately the arc of a circle corresponding to the pointer remaining practically stationary and indicating Alarm during the alarm period, during which time the projection I3 of the buzzer vibrates in the depression [2 of plate It). The alarm period may be of the order of one minute in length. At the end of the alarm period, pin 28 moves into the offset at 38, plate [0 rotates a corresponding distance counterclockwise, the vibrator is stopped by being p shed upward-by projection Hi, and a lower edge portion 3| of plate Ill moves downward against the forward end of shaft l1 and pushes it downward, thereby demeshing gear l8 from gear 23 and gear 16 from gear I5. This stops the timer operation although the motor may be allowed to continue to run. At this time the pointer 26 points to off on the dial 2'! and is the condition represented in Fig. 1. Of course when the alarm begins to sound, it may be turned off immediately by hand by means of knob 22. r

In order that shaft l1 may be pushed downward for the gear demeshing action described,

. the shaft has its bearing in a plate 32 pivoted at H. A spring 33 is provided which is biased to rotate plate 32 clockwise and hold the gears in mesh except as forcibly demeshed as above described. This eliminates backlash in the gears at this point during a timer operation. Preferably, the gear teeth are made thicker than usual to provide a rolling action without binding. The shaft I! is very much shorter than has been represented in the exploded representation of Fig. l and may beproperly supported by a single bearing in plate 32. The spring 33 is double-ended and its other end is hooked into an opening 34 in cam plate l0, and hence, the cam plate is biased by the spring to turn in a counterclockwise direction. This is the same direction that it would be driven by the timing motor, and hence, the spring tends to relieve the motor of load, the pin 28 riding on the outer edge of the spiral slot and moving downhill, so as to speak.

The central portion of spring 33 iscoiled about a supporting post (Fig. 2) to retain it in position. The winding action of the upper portion of the spring is accomplished by hand when the timer is set. The effective force of the upper end of this spring is preferably greater than that of the lower end.

To prevent possible damage to the cam pin 28, due to forcible movement of the same against the ends of slot 20 at the extremities of its travel, I may provide other stops as follows: At 36 is a stop on gear wheel 28 positioned to be engagedby a cooperating stop 3! on cam plate In to establish the ofi extremity of travel of the expanded scale timer parts as shown in Fig. 1.

It is evident that these stop will not engage when gear wheel 23 is rotated one or more revolutions in a clockwise direction, since then stop 3! on plate In will have moved upwardly and to the right out of the path of movement of stop 36.

To stop the parts at the upper limit of time setting, I provide a stop 38 on gear 20 positioned to engage with a stop 39 on plate l0 just before the pin 28 would reach the inner end of cam slot 23 At this time the stop 33 will have rotated about pivot point I I clockwise and upwardly from the position in Fig. 1 to position itself in the path of rotation of stop 38 rotating counterclockwise. The stops 3? and 39 on plate in are formed by bending sections of the plate to the rear.

' The operation of the timer is as follows: Starting with the off position represented in Fig. 1, the timer is set by turning knob 22 in a clockwise direction. Turning knob 22 clockwise or to the right turns gear 23 clockwise at the same time. Pin 28 will follow the groove 20 inwardly and as it passes through offset 30, plate [0 will rotate clockwise suificiently to mesh gears I8 and 20, and I5 and 18. As the depression 12 in plate It moves under the end 13 of the vibrator, the latter may sound momentarily if the motor is energized. Stop 33 moves downward and stop 31 outwardly to the right and clear each other. Pointer 26 is rotated clockwise through

gears

24 and 25, indicating Alarm when the pin 28 is between offsets 29 and 3B, and 0 on scale 21 as pin 23 moves past offset 29. After the motor is in gear with the timer, clutch.l9 slips during the setting operation. The setting operation-is continued until the pointer 26 indicates the desired setting time as, for example, 15 minutes as represented in Fig. 2. If the motor is not already energized, it is now energized or is energized as soon as it is desired to start the 15-minute timing period.

During the timing period the motor drives gear l5 counterclockwise, gear I6 clockwise, and gear 20 counterclockwise. Plate I0 is driven or allowed to move counterclockwise about pivot II as the pin 28 moves outwardly in the spiral groove 20 This drives pointer 26 counterclockwise towards off position. At the end of a 15-minute period pointer 26 reaches 0, pin 28 reaches the offset 29, depression l2 releases end [3 of the vibrator, and the buzzer sounds and there is a rapid movement of pointer 26 from 0 to Alarm. After a suitable alarm period such as a minute or, two, depending on the distance between offsets 29 and 30 of the cam slot, pin 28 reaches offset 30, plate [0 rotates a short distance counterclockwise, the alarm is stopped by rise I 4 as point 3| moves shaft l1 downward to demesh the gears and the pointer moves to off on the scale.

As soon as the gears are demeshed the gear 22 and other parts moved thereby stop during such automatic shut off action. Pin 23 will not have about reached the outer end of its slot, and the stop parts 36 and 37 may not have quite reached their engaging position, but this automatic off operation is sufficient to stop the alarm from sounding and to have moved pointer 25 to the off position. Instead of waiting for the alarm to shut off automatically, the user may shut the alarm off manually as soon as the alarm begins to sound by turning knob 22 counterclockwise. Such manual shutoff operation produces results similar to the automatic shutoff action, but is likely to'move the parts somewhat farther until stop parts 36 and'3i areengaged before pin 28 reaches the extreme outer end of its slot. Thus bending or other injury to pin 28, such as might occur if it wereused as a stop, is prevented.

It is of course evident that during a timing operation the user, may. readjust the timing period, if that is desired, by turning knob 22 and slipping .eclutoh; l9, or. hamay "I turn the; timerofi.

manually. While the timer; has been represented :as operating abuzzer signal at the end ofmthe timing;operation, the-signal may be. of any other type, visuals audible,-remote,- etc. Thus, in Fig.2,

.position.

It will .beevident that the characterof; the-scale expansion is-determined by the radial. slope of the {spiral cam 2 il :and that this is subject .to widevariation. ,Forinstance, :the upper end of the-:seale could beexpanded as. compared to 1 the lower end by makingithe radial-slopeof oam zii v reatest near itsinneriendrather than near-its outer-end. The scale expansion may be made uniform from end to end by;provi.ding-a cam with a uniform radial slope, etc.

Ingeneral the most useful arrangement'for a timer will be that represented, where the scale expansion is non-linear .and is largely at the lower end :of the scale. Fhus .in the example given for-the 60-minute timer there is a progressive expansion of the-scale ifrom'the -minute graduation downward and occupying-about onehalf of the-time scalev space; while the remaining upper end'of thescale'has asubstantially uniform distribution. The length of the spiral cam, i.-e.,one or more turns, is theoretically immaterial. For example, the same scale expansion which has been represented could be obtained with a single-turn spiral byin-creasing the slope in'proportion to decreasing the length. However, ,a multiple-turn spiral cam is desirable becauseathe scale expansion can be laid out more accurately,.the:time setting can be'made more accurately, 1 the load requirements for operating the scale expansion mechanism arereduced, and the increased amount of speed reduction obtained by the longerspiral cam reduces the amount of gear reduction otherwise required.

In the examplegiven a 66-minute timer has been represented. However, the timer may be designed for most any total time, several hours, for example; and in Fig. 3, I have represented a time scale for a total time of four'hours, where the lower end of the scale is graduated in minutes and the upper end in hours. The scaleexpansion at the :lower end or" thescale is of the order of 75 times that at the upper end of thescale. .The scale represented in Fig. 3=wouldirequirea reverse rotation of the parts and of the spiral cam but the design of a timer for such scale otherwise will be similar to that described, except for selecting the most appropriate gear reduction and length and slope of spiral cam.

In accordance with the provisions of the patent statutes I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an expanded scale timer, a constant speed timer motor, an indicating dial, a pointer indicating on said dial, a shaft on which the pointer is mounted and drive mechanism between the motonan'd pointer shaftby means of whichithe pointermay'be driven in a given direction with 'respecttosai-d dial at a nonuniform speed when said 'motor is in operation, said mechanism including a wheel driven by said motor at a uniwhen thecam wheel is turned, a gear sector on said member and a gear wheel on said pointer shaftmeshing with 'saidgear sector, said indicating dial being calibrated with respectto the movement cf the pointer as thus driven to indicate in time-units.

' 2. In an expandedscale timer, a 'constantspeed timer motoiya wheel driven by said motona multiple-turn spiral cam having the same axis of rotation as-and driven'by said wheel, said-spiral cam having'a nonuniform radial slope, a member pivoted to one side of the axis of rotation of said cam and extending adjacent said cam, a cam follower on said member in operative engagement with said-cam whereby when the cam is driven saidmember isswung about its pivot, a gear sector on said member, a pinion gear having the same axisof-rotationas said wheel meshing with said gear sector, a pointer driven by said pinion and asta-tionary dial over which said pointer moves, said dial having a scale calibrated with respect to the movement of the pointer in time units, signaling means operated by said timer as the cam follower approaches an end portion of the spiral cam, the operation of said signaling means corresponding to the arrival of saidpointer at one end of the time scale, and means responsive tothe further operation of said timer following such signaling operation for interrupting the operation of said timer.

3. An expanded scale timer, comprising a constant speed timer motor, a wheel driven by said motor through a slip friction clutch, a multipleturn spiral cam having the same axis of rotation as-said wheelanddriven by said wheel, a member pivoted on an axis parallel and to one side of the axis of rotation of said cam and extending adjacent said cam, a cam follower on said member in operative engagement with said cam whereby the member is swung about its pivot when the "cam is rotated, a gear sector on said member, a pinion gear meshing therewith, a pointer driven by said-pinion gear, a graduated scale "on which said pointer indicates calibrated from zero upward to indicate the movement of said pointer in time units, manual means for turning said wheel to set the pointer to any desired scale indication, such setting being permitted by slipping of the friction clutch, and the pointer then indicating the time required to drive the pointer to the zero scale position, said spiral cam having a large radial slope over the range of operation corresponding to the movement of the pointer over the lower end of the scale as compared to a smaller radial cam slope corresponding to the movement of the pointer over the upper end of the scale whereby the lower end of the time scale is expended as compared to the upper end.

4. An expanded scale timer, comprising a constant speed timer motor, a cam wheel driven thereby through a slip friction clutch and gearing which may be disconnected, said cam wheel having a multiple spiral cam formed thereon, a member pivoted on an axis parallel to and to one side of the axis of rotation of said cam wheel, a cam follower on said member in operative engagement with the spiral cam such that as the cam wheel rotates the member is swung about its pivot, a gear sector on said member, a pinion gear meshing therewith, a pointer driven by said pinion gear, a scale on which said pointer indicates, said scale being graduated from end to end with the indications off, alarm or equivalent expressions and in time units from G upward, said pointer having a range and direction of movement when driven in response to the operation of said motor from the upper end of the time scale downward through the 0, the Alarm and to the off indicating positions as the cam follower traverses from the inner end to the outer end of the spiral cam, the greater portion of the length of the spiral cam having a radial slope which is smallest at the inner end and largest towards the outer end which corresponds to the movement of the pointer over the time graduated portion of the scale, the spiral cam having two offsets near its outer end separated by a section which has no radial slope, the inner offset corresponding to the scale pointer position, the portion of no radial slope corresponding to the Alarm pointer position and the outer end of the cam beyond the outer offset corresponding to the off pointer position, an alarm, means subject to the operation of said timer to and from the Alarm pointer position condition for respectively turning on and ofi said alarm, means responsive to the operation of said timer to and from the oil pointer position condition for respectively disconnecting and reconnecting the gearing between the timer motor and cam wheel, and manual means for setting said cam wheel from any pointer position condition to any other pointer position condition, such setting being permitted by reason of said slip friction clutch when the gearing is connected.

5. An expanded scale timer, comprising a selfstarting synchronous motor, a cam wheel driven by said motor through a, driving connection which permits setting the cam wheel relative to the motor, a multiple-turn spiral cam of nonuniform radial slope formed on said cam Wheel, a, member pivoted on an axis parallel to and to one side of the axis of rotation of the cam Wheel, a cam follower on said member in cooperative engagement with the spiral cam whereby when the cam wheel is rotated the member is caused to swing about its pivot, a time graduated scale, a pointer which is moved over said scale and beyond in response to the movement of said member by said cam, a magnetic vibrator alarm energized by flux from said motor, said pivoted member having a, cam periphery including a raised portion which moves past and engages said vibrator alarm and prevents the same from vibrating when the pointer of the timer is moving over the time graduated scale, a depressed portion which moves opposite said vibrator and allows the same to vibrate as the pointer moves ofi one end of said time scale, and a second raised portion which engages said vibrator and prevents the same from vibrating when the pointer moves further in the ofi direction from said one end of said scale, and means subject to the movement of said pivoted member to the last-named position for interrupting the driving connection between said motor and cam Wheel.

6. In an expanded scale timer, a cam wheel which is adapted to be driven at a uniform speed in a given direction for time measurement purposes, a multiple-turn spiral cam of nonuniform radial slope mounted on said wheel, a member pivoted on an axis parallel to and to one side of the axis of rotation of said cam wheel and extending adjacent said cam, a cam follower on said member in operative engagement with the spiral cam and by means of which said member is caused to swing about its axis when the cam wheel is rotated, time measuring indicating means comprising a time scale and pointer one of which is moved relative to the other in response to the movement of said pivoted member, a pair of stops one on said pivoted member and the other on said cam wheel positioned to be engaged to stop the cam wheel as it approaches one limit of its range of travel before the cam follower reaches one end of the spiral cam, and a second pair of stops'one on the pivoted member and the other on the cam wheel positioned to be engaged to stop the cam wheel as it approaches the other limit of its range of travel before the cam follower reaches the other end of the spiral cam.

HOWARD A. WYMAN.

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

UNITED STATES PATENTS Number Name Date 1,902,508 Kearsley Mar. 21, 1933 2,261,723 Hoffman 'Nov. 4, 1941 2,565,017 Brown Aug. 21, 1951 2,610,683 Beiser Sept. 16, 1952