US1837929A - Spring winding mechanism - Google Patents

Description

Filed Nov. 1'? 1930 Inventor: Henry BVVarren His ttorneg.

Patented Dem 22,1931

\ UNITED/STATES PATENT OFFICE HENRY E. WARREN, OF ASHLAND, MASSACHUSETTS, ASSIGNOR TO WARREN TELE- OHRON' COMTANY, F ASH-LAND, MASSACHUSETTS, A CORPORATION 01 MAINE srmrre wmmne mncnamsm:

Application filed November 17, 1930. Serial 1T0. 496,046.

' My invention relates primarily to a spring winding mechanism adapted for maintaining the spring of clocks and other springoperated devices wound toa substantially uniform condition. I prefer to employ an elecgtric motor for winding the spring or springs and when this motor is of the synchronous I type operated from a regulated frequency source of alternating current it may be and preferably is also employed, in combination with the other features of my invention, to assist in regulating or synchronizing the spring driven clock movement with the fre quency of the alternating current supply,

thereby increasing thereliability of appa ratus' as an accurate timing device.

In the form of the invention illustrated the electric motor winds the clock spring or springs through a cam actuated pawl operating upon a ratchetwheel connected'to the spring winding arbor. A second pawl ordinarily prevents the ratchet wheel from back-' ward rotation, but this second pawl is'resiliently mounted and changes its position with respect to the teeth in the ratchet wheel as the counter tension. of the clock spring approaches that corresponding to a fully wound condition. When the clock spring becomessubstantially fully wound the position and movement of the retaining pawl is such that it no longer drops behind a tooth in the ratchet wheel .as the latter isadvanced and the mechanism ceases to wind the clock spring until its tension is decreased slightly. The

- same motor may actuate a pair of such de-.

vices, one for the winding of the main clock spring and the other for Winding the spring which actuates the clock striking mechanism.

The features of my inventionwhich are believed to be novel and patentable will, be

7 pointed out in the claims appended hereto] v For a better understanding of my inventlon.

reference is made in the following description to the accompanying "drawings, Fig. 1 of which'shows a perspective .exploded view of spring operated nected to theclock hands forsynchr'onizing' striking clockwork equipped with the spring winding mechapurposes as will be explained; Fig. 2 is a more detailed view of the spring winding mechanism, Fig. 3 is an explanatory view of the ratchet wheel with theretaining pawl in the active or winding positions, and Fig. 4 is a modification of the invention.

Referring first to Fig. 1 10 is a clock spring having its inner end fastened to a winding arbor 11 and its outer end connected to a gear 12 (free to turn on arbor 11) which gear is connected to drive the clock hands 13 through suitable gear trains comprising gears 14, 15 and 16 leading to the minute hand and gears 14, 17 and 18 leading to the hour hand. An ordinary escapement mechanism represented at 19 is connectedto the minute hand shaft through a gear train rep. resented by 23. It will be understood that the parts just described may represent any well known spring driven clock movement.

' At 24 is a second spring with its inner end fastened to a winding arbor 25, and its outer I end connected through gears 26 and 27 to a clock striking mechanism contained within the casing 28. Lever 29 represents a release lever for the strike mechanism operated every half hour from the'clock train through cam 30. 31 and 32 respectively represent the gong and hammer of the strike mechanism. I have not shown the details of this strike mechanismqas its construction constitutes 'no partof my inveintion but it will be understood that any well known strike mechanism is intended. v

I will now describe the spring winding mechanism-ofimy invention used to maintain the springs 10 and 24 wound to a substantially uniform tension.' 33 represents a rotary motor which, if also used for assisting in keeping the clockwork synchronized, is of the electric synchronous type and may be similar to that described in my United States, Patent No. 1,546,269, July 14, 1925. This motor is con nected through gears 34 and 35 to a cam shaft 36 on which is mounted three cam eccentrics, two of which may be seen at37 and 38. Upon these eccentrics are mounted cam pa- wls 39, 40 and 41. -The pawls have bearing surfaces fit ting the eccentrics and as the eccentrics are rotated the pawls are reciprocated. Pawls40 and 41 actuate ratchet wheels 42 and 43 mountedon the winding arbors 11 and 25 of the springs 10 and 24 respectively. Each pawl has its center of gravity so positioned with respect to its pivot point on its eccentric as to have its ratchet surface remain in contact with its corresponding ratchet wheel by the force of gravity. Thus the ratchet 40 is biased against ratchet wheel 42 by reason of the fact that the ratchet tends to turn in a counter-clockwise direction about the bearing surface on its eccentric by reason of the greater weight of the enlarged or rear end of ghe pawl located to the left of the cam surace.

The retaining pawls for ratchet wheels 42 and 43 are represented at 44 and 45 respectively and since the mounting and operation of both are similar an explanation of one will sufiice. Pawl 44 is mounted on an arm 46 which is pivoted on the same axis of rotation as the spring winding shaft 11 on which the ratchet wheel is mounted. Rotational movement of arm 46 is limited by means of stop pin 47 mounted within the forked upper end of the arm. The position of this pin is adjustable to a limited extent and between it and the upper end of arm 46 is a resilient U- shaped spring 48. This spring is so positioned and tensioned that it tends to rotate arm 46 in the direction in which the ratchet wheel is advanced in winding the spring and to hold the upper end ofthe arm 46 to the left against the stop pin 47 and it does so as represented in Fig. 3, when the clock spring 10 is wound to less than a predetermined tension. Under these conditions'there is no movement of arm 46 and the retaining pawl 44 drops behind a tooth in ratchet wheel'42 as the latter is advanced by each reciprocation of the ratchet 40 and the clock spring is thus slowly woundby energy received from'the'electric motor. However as soon as the clock spring becomes substantially wound the counter torque becomes suiiicient to rotate arm 46 against the tension of spring 48 causing arm 46 to rotate slightly in a clockwise direction and "moving its top to, the right until it rests against the other side of stop pin 47 as illustrated in Fig. 2. This counter torque of the clock spring acts through retaining pawl 44 when the advancing pawl 40 is retracted and causes the ratchet wheel 42 to rotate backward the same distance it is advanced. Thus arm 46 and pawl 44 rotate slightly back and forth about shaft 11 as the pawl 40 reciprocates. The movement of the retaining pawl between the two positions is preferably slightly less than the spacingbetween the ratchet teeth escapement end. When the clock spring hasrun down sufliciently for spring 48, acting through arm 46 and pawl 44, to overcome the counter-torque, arm 46 is forced over to the winding position, Fig. 3, and the pawl and ratchet mechanism is again effective to wind the clock spring. Spring 48 is preferably so arranged that it exerts its strongest action in the Winding position, Fig. 3; consequently there is no tendency-for the arm 46 to rest in an intermediate position of equilibrium and the change of the mechanism from a winding condition to an ineffective condition and vice versa is positive.

In operation, the motor 33 is connected to a suitable source of supply and is normally in continuous operation. When either of the springs 10 and 24 become unwound to a tension below that for which the apparatus is adjusted the correspondin control mechanism will function to ma e the pawl and ratchet spring winding mechanism effective. By proper adjustment the springs will be maintained wound to a substantially uniform tension without danger of overwinding. The clock springs will-preferably be of sufficient length so that in case of failure of the source of supply for a few hours the clock will not cease to function. When a plurality of winding mechanisms are actuated by the same motor it will be desirable to so arrange the cams that the advancing strokes of the cam pawls will occur at difierent points in the rotation of the cam shaft so as to equalize the load on the motor.

When the electric motor 33 is of the synchronous type connected to a regulated frequency source of power I prefer to use it for directly assisting in the regulation of the clock. To this end I have represented the third pawl 39 and ratchet wheel 50 driven from the cam shaft 36. Ratchet wheel50 is connected directly with the clock hands through a suitable gear train represented in fact by 51 and it will be understood that when the frequency of the source of supply is correct the clock hands may be driven through this gear train at the correct rate for the clock. Should the spring driven clock movement as determined by the escapement tend to be slow this connection to the synchronous motor will nevertheless force the clock to runat its proper rate. Should the clock escapement tend to allow the clock to run fast the synchronous motor connectionwill produce a slight additional load or drag on the spring driven clock nechanism tending to correct it. However this connection to the synchronous motor should contain a one-way drive such as an overrunning clutch, so that in case the motor stops, the spring driven clock movement will maintain the clock in operation. The ratchet wheel 50 and pawl 39 may serve to illustrate such overrunning clutch but it may be desirable to provide it nearer the clock end of the synchronous motor drive train.

' It has been found that the spring winding 7 spring pawl is bent slightly and rests near its center against a stop 54 when in its active retaining position. When the counter torque of the clock spring (not shown) exceeds a predetermined amount spring pawl 52 will bend to the dotted line position with its center resting against a second stop 55. This is the inactive position. It is evident that this spring pawl will exertits maximum resilient retaining force in the full line position.

' The stops 54 and 55 and the support 53 may Letters Patent of the United States, is:

.be adjustable inposition to obtain the most desirable action.

What I claim as new and desire to secure by 1. A spring winding device comprising in combination with a spring, a ratchet wheel connected in winding relation to said spring, an advancing pawl for advancing said ratchet wheel to wind said spring, a motor for actuating said pawl, a retaining pawl --for normally preventing backward rotation of said ratchet Wheel after being advanced, a support for said retaining pawl mounted for limited rotational movement about the axis of rotation of said ratchet wheel, and resilient means tending to rotate said support in the direction in which the ratchet wheel is advanced towind the spring. a 2. Apparatus for winding'a spring to substantially a uniform tension, comprising" 1n combination with a spring, a ratchet wheel for winding the same, an advancing pawl for the ratchet wheel, means for actuating said pawl, a retaining pawl for the ratchet wheel, a support for the retaining pawl having limited rotational movement about the axis of rotation of said wheel, resilient means biasing the support in the direction in which the ratchet wheel is advanced in winding the minimum biasing force when overcome by the counter torque of the spring.

3. In apparatus of the character described a pluralityof torsional springs, a rotary motor for winding said springs, a cam shaft driven by said motor, cam pawls reciprocated by said cam shaft, a ratchet wheel in winding relation with'each spring advanced by one of said cam pawls, retaining pawls for normally maintaining the advance of said ratchet wheels against the counter torques of the springs when the cam pawls are retracted, and resilient control means for each spring responsive to its counter torque for rendering the corresponding retaining pawl inefi'ective when the spring is substantially fully wound, the control means for the diffeient springs acting independently of each 0t e1.

4. In apparatus of the character described, a torsional, spring, a clock movement driven by said spring, a synchronous electric motor for winding said spring and regulating said clock movement, a cam shaft driven by said motor, a pair of cam pawls reciprocated by said cam shaft a pair of ratchet wheels advanced by said pawls, one of said wheels being connected to regulate the clock movement andthe other being connected to wind said spring, a retaining .pawl for the last mentioned wheel for normally maintaining the advance of the wheel against the counter torque of the spring when the corresponding advancing pawl is retracted, and control means responsive to the counter torque of the spring for rendering the retaining pawl ineffective when the spring is wound to a pre: determined tension, said control means acting mdependently of the regulating function of the synchronous motor on the clock move-' ment.

Inwitness-whereof, I have hereunto set my hand thls 10th day of November, 1930. HENRY E. WARREN.

spring. said resilient means being adjusted to predominate over the counter torque of the spring, acting through the retaining pawl and support, so asto maintain the retaining pawl in a fixed active position until the spring is substantially fully wound and thereafter to be overcome by the counter torque of said spring as the advancing pawl is retracted to allow the retaining pawl and its support to rotate backward and thereby prevent further winding of the spring until its tension is reduced, said biasing means exerting its

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