US2610683A

US2610683A - Interval timer

Info

Publication number: US2610683A
Application number: US117854A
Authority: US
Inventors: Elmer H Beiser
Original assignee: General Time Corp
Current assignee: General Time Corp
Priority date: 1949-09-26
Filing date: 1949-09-26
Publication date: 1952-09-16
Anticipated expiration: 1969-09-16

Description

Sept. 16, 952

E. H. BEISER INTERVAL TIMER 3 Sheets-Sheet Filed -Set. 26, 1949 PIE-1..

F1 5 INVENTOR ELMER H. BEISER BY AT TORNE Y E. H. BEISER INTERVAL TIMER Sept. 16, 1952 3 Sheets-$heet 2 Filed 'Sept. 26. 1949 FIEEL INVENTDR ELMER H. BEISER ATTORNEY Patented Sept. 16, 1952 INTERVAL TIMER Elmer H. Beiser, Peru, 111., assignor to General Time Corporation, New York, N; Y., a corpora tion of Delaware .Applicationseptember 26, 1.949., SerialNo. 117,854

9 Claims.

This. inventionrelates to a timing device and especially to a timing deviceifor sounding a signal after the passage. of a predeterminedinterval of time.

One object of this invention is to provide aninterval timerin which the indicator does. not move over the dial at a uniform rate, but insteadv moves at. a.- gradually increasing rate as it approaches zero.

Another object is. to provide an interval timer in which. the gears may .have considerable play, but said play is not transferred to the indicator.

Still another object is to provide a timer that will be simple and economical to manufacture by mass. production methods.

Spring driven timers that-sound a gong after the passage of a predetermined period (usually an hour or less) have been known for many years. Most of the earlier timers had a dial that was graduated by uniformly spaced markings. Because these timers have to be fairly small and, therefore, have a small dial, a uniformly spaced dial was not satisfactory for setting a small period of time, such as five minutes or less.

A later development in interval timers, such as shown in United States Patent 2,261,723 issued to C. T..Hoffman on November 4-, 1941, was the provision of a pair of co-acting spirally shaped gears connecting the output shaft of the timer to the indicator shaft. With this arrangement it was possible to use a dia1 having non-uniformly spaced minute markings. The principal objection to this timer lies in the fact that the indicator shaft has sufiicient play due to manufacturing tolerances to move freely as. much as two min- Q ute dial spaces. This is true. because the only thing that prevents the. indicator from moving is the: intermeshing spiral gears. Since it is difficult to provide a very accurate mesh in spiral gears all timers of this type wherein the indicator is on a separate shaft and driven through spiral gears presented an indicator with considerable play. On a three minut setting, two minutes of play could give more than a 50 per cent error.

The present timer overcomes the above mentioned difficulty by mounting the indicator on the main shaft and using the spiral gears to drive a variable speed escapement instead of using the spiral gears to connect the main shaft and the indicator shaft as was done previously. By the use of the present invention the main spring at all times biases the main shaft with the indicator knob toward the zero mark on the dial. Thus the gears may'have as much play as manufacturing tolerances require, but said play does not effect the setting of the indicator since it is always biased toward zero by the main spring, thereby taking up any play in said gears.

The present timer has an additional advantage because it combines a variable rate escapement with the spiral gear drive to secure an even greater variation in indicator speed than is possible with a uniform rate escapement.

In the accompanying drawings in which is illustrated one embodiment of the invention:

Fig. 1 is a front elevational view of aninterval timer embodying the present invention;

Fig. 2 is a side elevational view of said device;

Fig. 3 is a front elevational view of the interval timer with the dial removed taken on the line 3-3 of Fig. 8 and showing the main shaft in the zero position; v

Fig. 4 is a view similar to Fig. 3 showin the main shaft set at approximately the three minute position;

Fig. 5 is a front elevational view of the signal cocking cam;

Fig. 6 is a front elevational view of the signal releasing cam;

Fig. 7 is a front elevational view partly in crosssection taken on the line 'l'! of Fig. 8;

Fig. 8 is a cross-sectional view taken on the line 8--8 of Fig. 1;

Fig. 9 is a cross-sectional view taken on the line 99 of Fig. 3;

Fig. 10 is a crossesectional-view taken on the line l0-IC Of Fig. 3;

Fig. 11 is an elevational view partially in crosssection taken on the line I Ill of Fig. 8;

Fig. 12 is an expanded view of the ear train of the interval timer; and

Fig. 13 is a graph showing the number of degrees traversed by the indicator plotted against the speed of one of the ratchet wheels of the es capement.

Referring particularly to Figs. 1 and 2, a base 2! supports a vertical dial plate 22 on which is printed a dial 23. The time movement 24 is secured to the dial plate by lugs 25 and screws 26. An indicator knob 21 having a pointer 29 is fixed on the main shaft so that it will rotate over the dia1 23. The dial 23 bears indicia from 0 to 60 minutes, with the angular spacing between like time intervals decreasin as the pointer moves from 0 to 60. A stop 20 is secured to the dial near the 60 minute mark so that the indicator cannot be turned past said stop.

The timing train will be described by reference to Fig. 12 which is an expanded view of said train. Surrounding the main shaft 28 and fixed thereto is a main spring 30 that tends to rotate main shaft 28 in a counter-clockwise direction. Also fixed to the main shaft 30 is a spirally shaped gear SI and cam disc 32 which cocks a signal. A second cam disc 33 for releasing the signal is freely rotatable on shaft 30. The function of

cam discs

32 and 33 will be described later.

Meshing with spiral gear 3i is a second spiral terial.

Spider 3G coacts with a pair of metal washers 37 and a pair of fiber washers 38 to frictionally grip and thereby drive a gear 39 which is rotatably mounted on shaft 35. Gear 39 in turn drives pinion 40 to which is affixed gear 45!. Gear 4] drives pinion 42 to which is aifixed gear 43. Gear 53 drives pinion 44 to which is'affixed gear 45; and gear 45 in turn drives pinion 46, thereby driving an escapement Iii.

Escapement 31 comprises intermeshing

ratchet wheels

48 and 49 and oscillating disc 50 having pins El and 52 mounted on one side thereof and adapted to cooperate with the teeth of said ratchet wheels. The pins and 52 project at right angles to the plane-of disc 58 with the two pins and the axis of the disc forming substantially a straight line. The teeth of the ratchet wheels are generally pointed and adapted to'strike the pins 5| and 52. As shown in Fig. 12, one tooth of ratchet wheel 43 turning in a clockwise direction is about to strike pin 52.

This causes disc Ell to rotate in a clockwise direction until pin 5! is struck'by a tooth of ratchet wheel 69 turning in a counter-clockwise direction. Disc 50 then rotates in a counterclockwise direction until pin 52 strikes the next tooth of ratchetwheel- 43 and the cycle is complete.

It will then be seen that the oscillation of disc 58 controls the rate at which

ratchet wheels

42 and 49 are allowed to rotate and this in turn throughthe train of gears controls the speed of rotation of the main shaft under the influence of mainspring 39.

The rate of oscillation of disc 5%] depends on (1) the inertia of the'disc, (2) the length of are through which the disc oscillates, and (3) the amount of torque delivered to the ratchet wheels from the gear train.

The inertia of the disc is constant for any given escapement. The length offarc'through which the disc oscillates depends on the spacing of the pins from the ratchet wheels. The closer the pins are positioned to the teeth of the ratchet wheels, the smaller the arc of rotation and the faster the rate. This feature may be used as a convenient method'of adiusting the rate of the escapement if the hearings in which disc 5% rotates are mounted on a movable bracket so that the disc may be moved toward or away from the ratchet wheel.

The torque delivered to the ratchet wheels 48, A9- is dependent on the amount of energy in' spring and the ratio of the gears through which power is transmitted to. said ratchet wheels. In an ordinary clock movement the gear ratio is constant, but in the present movement the gear ratio between the spring 3i! and the escapement is varied by meansof the spiral gears iii, 34. Thus with the indicator knob 2'! set at 60 minutes the main shaft 28 will rotate approximately one degree to two degrees of rotation of shaft 35. Near the zero setting (the position shown in Fig. 12) the main shaft will rotate approximately two degrees to one degree of rotation of shaft 35. Since the mainspring need onlyturn the main shaft about one full turn, a mainspring with several turns may be used that will deliver practically a constant force for one complete turn of the main shaft. Therefore, the torqueon the escapement will be approximately four times as great with the indicator near zero as it is with the indicator at sixty minutes. The ordinary lever type clock escapement will not operate properly with this much mainspring 3t.

4 variation in torque. It will either overbank or lock. 7 However, the abovedescribed escapement, having no hairspring, cannot overbank. Instead the escapement operates perfectly but its rate increases as the torque increases.

As shown in Fig. 13 in the present embodiment the revolutions per minute of escape wheel 43 are almost twice as many with the indicator knob 21 near zero degrees than they are with said indicator at 340 degrees. This variation in escapement rate allows a larger space between minute markings near zero than would be possible with a constant rate escapement. Thus with the spiral gears of the present embodiment but using a constant rate escapement, the ratio of distance between minute markings at 60 minutes and minute markings at zero would be approximately 1 to 4. With the present variable speed escapement said ratio is approximately 1 The escapement ll and its associated gear train are mounted in plates 60 and BI supported on pillars B2. A gong 62 encloses the movement (see Fig. 8).

The signal mechanism is mounted on the front of plate so and behind the dial plate 22. .This mechanism is shown most clearly in Fig. 3 in which the signal is shown in the released'positicn and in Fig. 4 in which the signal is shown in a cooked position. As described above, a cam disc 32 is secured to mainshaft 28 and a second disc 33 slightly larger than disc 32 is mounted in close proximity to disc 32, but is freely rotatable on shaft 28. Disc 32 has a notch Ed in its periphery, said notch-having a sloping edge 65 and a radial edge 56. Disc 33 also has a notch 57 in its periphery, but both edges 68 are substantially radial. I Disc 33 is provided with an arcuate slot 69 through which passes a pin it that is secured on one end to disc 32 and on the other tospiral gear 3!. Y 1

A hammer lever H is pivotally mounted on plate 65. An inwardly projecting pin 72 secured to lever H is adapted to ride on the periphery of disc 33 as lever H is biased toward said disc by a tension spring 13.

Numeral l4 designates a movable hammer having a slot l! in one end that is slidable on rivet 15 which is secured to plate 69. A slot 18 in the other end of the hammer surrounds rivet 16 secured to the free end of lever ll. As shown in Fig.3, when the pin 12 is at the bottom of

notches

64 and 61, the upper edge of slot 18 rest on rivet l6 and the striking face vl9 of the hammer is close to but does not touch the gong E4.

When the indicator knob 21 is set at zero, as shown in Fig. 1, the

discs

32 and 33 are in the position shown in Fig. 5 with the pin l2 resting in the bottoms of notches b4 and 6?. As the operator turns the indicator knob 21 to a desired position, for example 15 minutes, the following operations take place. First, the rotation of the mainshaft 28 places additional tension on the Second, spiral gears 3|, 34 are rotated and shaft 35 with spider 36 rotates with them. However, gear 39 and the gear train will not rotate because of the holding action of the escapement 47. Third, disc 32, being secured to spiral gear 3 I, rotates with said gear lifting pin l2 by means of the sloping edge 65 of notch 6d and thereby tensioning spring 13. Disc-33 does not start tomove until pin H1 contacts the end of arcuate slot 69 at which time pin 12 has been lifted to the periphery of disc 32 and is ready to contact the periphery of disc 33. Disc 33 then moves forward with disc 32 and since disc 33 is a little larger than 32, the pin 12 rides on its periphery.

As the operator releases the indicator knob, mainspring 36 immediately starts rotating the mainshaft 28 in a counter-clockwise direction toward zero. The friction spider 36 now drives the escapement 41 through the gear train so that the rate of return to zero is controlled by the escapement. As the mainshaft rotates counterclockwise disc 32 rotates with it, but disc 33 remains stationary until pin contacts the opposite end of arcuate slot 69. At this position notches 64 and 6'! are in alignment and the two discs move together until the indicator knob reaches zero. At this time pin 12 drops off the radial edge 68 of notch 67 allowing lever H to move upward quickly. This motion throws hammer 14 upward. While the upward motion of lever H is arrested when pin 12 strikes the bottom of notch 61, the hammer continues to move by inertia until it strikes the song. It then falls back to the position shown in Fig. 3. This action of the hammer whereby it is thrown freely against the gong and then falls away from said gong, produces a loud, clear ring.

In order to use the timer it is merely necessary for the operator to turn the indicator knob to the desired setting. If the setting is to be less than five minutes, the knob is turned to the five minute mark first and then back to the desired setting. This minimum movement is necessary in order to be sure that the hammer mechanism is fully cocked. After setting, the indicator knob is driven back to zero by the mainspring under control of the escapement.

It is an important feature of this invention that any looseness or play in the gear train is taken up by the mainspring that constantly biases the mainshaft toward zero. Therefore, if there is play in the gears, the operator need only move the indicator slightly past the desired setting and then back to said setting. Since the mainshaft is biased in this direction, the setting will be accurate and there can be no error in the indication caused by the gear train.

The above description is meant to be illustrative only as many changes can be made without departing from the spirit of the invention.

What is claimed is:

1. In an interval timer the combination comprising a dial having non-uniformly spaced markings thereon, an indicator cooperating with said dial, a rotatable shaft for driving said indicator, a spring having one end secured to said shaft for biasing said shaft in one direction, a first spiral gear secured to said shaft and rotatable therewith, a second spiral gear meshing with said first gear, and an escapement means geared to said second spiral gear for controlling the rate of rotation of said shaft under the influence of said spring.

2. In an interval timer the combination comprising a rotatable shaft having an indicator thereon, a spring having one end secured to said shaft for biasing said shaft in one direction, a first spiral gear secured to said shaft, a second spiral gear driven by said first spiral gear and means associated with said second spiral gear for controlling the rate of rotation of said shaft under the influence of said spring.

3. In an interval timer the combination comprising a rotatable shaft, an indicator secured to said shaft, 9, spring having one end secured to said shaft for biasing said shaft in one direction, a first spiral gear mounted on said shaft,

a second spiral gear driven by said first spiral gear and an escapement having a variable rate driven by said spring through said spiral gears for controlling the rotation of said shaft under the influence of said spring.

4. An interval timer comprising a mainspring for rotating an indicator shaft and means to control the speed of rotation of said shaft, said means including a pair of meshing spiral gears and an escapement having a variable rate driven by said mainspring through said spiral gears.

5. In a timing device the combination comprising a dial having time markings thereon with decreasing angular spacing between equal time intervals as said dial is marked from minimum to maximum time, an indicator adapted to be moved over said dial, a shaft secured to said indicator, a gear train connecting said shaft to an escapement, a spring having one end secured to said shaft for biasing said shaft in one direction and means in said gear train to vary the torque exerted by said spring on said escapement in direct ratio to the variation of said time markings. I

6. In a timing device the combination comprising an indicator, a spring biasing said indicator in one direction, an escapement and means including spiral gears connecting said spring to said escapement whereby the torque exerted by said spring on said escapement is varied over the range of said indicator.

'7. A device as defined in claim 6 wherein the escapement has rate that is proportional to the torque exerted on said escapement.

8. In an interval timer the combination comprising a spring for rotating an indicator shaft, a first spiral gear secured to said indicator shaft, a second spiral gear meshing with said first spiral gear and driving through a gear train an escapement including two intermeshing ratchet wheels, an oscillating member, and two pins mounted on said member adapted to cooperate with the teeth of said ratchet wheels whereby a tooth of the first ratchet wheel striking the first pin oscillates said disc in one direction until a tooth of said second ratchet wheel strikes the second pin reversing the direction of said disc and thereby controlling the speed of rotation of said indicator shaft.

9. In an interval timer the combination comprising a dial having non-uniformly spaced mar-kings thereon, an indicator cooperating with said dial, a rotatable shaft affixed to said indicator, a spring having one end secured to said shaft for biasing said shaft in one direction, a noncircular gear secured to said shaft, a second noncircular gear driven by said first gear, and means associated with said second gear for controlling the rate of rotation of said shaft under the influence of said spring.

ELMER. H. BEISER.

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

UNITED STATES PATENTS Number Name Date 1,213,716 Wentworth Jan. 23, 1917 2,261,723 Hoffman Nov. 4, 1941 2,334,950 Opocensky Nov. 23, 1943 OTHER REFERENCES Scientific American of February 27, 1904; page 23537, Fig. 15.