US2146119A - Electric clock mechanism - Google Patents

Description

Feb. 7, 1939.

I ELECTRIC CLOCK MEGHANISM Filed March 2, 1936 2 Sheets-Shet 1 I Mg III

J. w. HOBBS 2,146,119

Feb. 7, 1939. J. w. HOBBS 2,146,119

ELECTRIC CLOCK MECHANISM Filed March 2, 1936 2 Sheets-Sheet 2 Q), INSULATION ME I U L 0//77/7 /70%%S Patented m. 1, 1939 PATENT- OFFICE 2,140,119 amc'rnrc cnocx MECHANISM John w. Hobbs, Chicago; m., assignor id The George W. Borg Corporation, Chicago, 111., a corporation of Delaware Application March 2, 193d, Serial No. 66,532

4Claims.

to provide an improved automatic winding mechanism for a spring driven clock.

Another object is the provision of an electrically actuated winding mechanism for a clock, which is automatically deenergized when the clock is wound and energized'when the clock approaches a run down condition.

A further object of the invention is the provision, in a clock of the character described, of protective means for preventing overheating and 'possible damage of the winding mechanism, due to abnormal energization thereof.

It is also an object of this invention to provide a protective device which will automatically disconnect the winding mechanism relative to the electrical source when abnormal heating occurs, and which will also operate to automatically reconnect the electrical supply as soon as the winding mechanism has cooled to a safe operating temperature.

A still further object resides in the provision of novel means whereby actuation of the timing mechanism will becontinued without interruption during the interval in which the winding mechanism is being rewound.

In accordance with the general features of the preferred form of the invention, it is proposed to.

provide a conventional timing mechanism having a main driving gear which is retained against reverse movement. by means of a detent pawl. main driving gear is actuated in a forward direction by means of spring pressed pawls carand that for rewinding the clock, energization of i the magnet will move the armature to a new position, thereby again tensioning the actuating driving spring.

The rewinding is accomplished automatically by means of a switch which is actuatedin response to the movement of the armature, so that as the armature reaches a run-down position, the

switch is closed to energize the electro-magnet The,

and return the armature to a position wherein the driving spring is again stressed. At this position, the movement of the armature operates to open the switch and demagnetize the electromagnet.

The automatic winding device is arranged to operate from the storage battery of the automobile, and it has been found that when the battery is low. or during starting of the car, particularly in the winter time, there is insumcient voltage to 10 energize the electro-magnet sufficiently to move the armature and open the deenergizing switch in circuit with the electro-magnet winding. Under these conditions, the electro-magnet is energized for anabnormal period of time, with the 15 result that the coil of the electro-magnet becomes overheated and there isv a possibility of its being burned out or otherwise damaged.

To overcomethis condition and protect the coil, it is proposed as an additional feature of the 20 invention to provide a thermostatic switch, which will open the electro-magnet winding circuit when abnormal energization of the electro-magnet occurs. This switch consists of a bimetallic strip which, due to the flow of current for an 25 abnormal period, will be flexed away from an associated contact and open the circuit. After a brief interval of approximately one minute, the bimetallic strip will have cooledsufiiciently to re-establish the connection to the electro-mag- 30 net, whereby the armature will again be attracted to restress the spring. As soon as normal operating conditions are established with normal battery voltage, the thermostatic switch will remain closed and the switch which is 8.61111:- 35 ated in response to the movement of the armature will again function to automatically ener gize and deenergize the electro-magnet and keep themainoperating spring stressed at all times.

' In order to prevent the clock from stopping during the rewinding or restressing of the main driving spring, a novel secondary or supplemental drive is provided. For this purpose, a spring connection is provided between the main driving gear and the driving shaft, the main gear being 5 mounted for relative movement on the shaft. This. spring is stressed during the time when the clock is being driven by the main driving spring and will continue the drive of the clock for a brief interval, during which time the elec- 5o tromagnet may act on the armature to again rewind or stress the main driving, spring. The

operation of the foregoing features will be more apparent from the following description.

Other objects and features of the invention will 55 mostatic switch for the electro-inagnet of the winding mechanism, taken substantially on. the line IV--IV of Figure 1;

Figure 5 is an elevational view showing the details of the electro-magnet and the thermostatic protective switch, when viewed from line V--V of tially on the line VI-VI of Figure 1.

Figure 4; and

Figure 6 is a detail view in section showing the operative relationship betweenrthe' parts of the secondary. driving mechanism, taken As shown on the drawings: Figure 1 of the drawings illustrates a clock which embodies the features of the present invention.- This clock is composed of a. timing so mechanism, generally indicated at A, having a conventional escapement, gear train, hands and dial; and power means, generally indicated at B, including a main driving spring and an electrical rewind for intermittently stressing the main drivins spring.

The timing mechanism includes a main shaft I 0 for driving the minute hand, this shaft having secured thereto for rotation therewith a pinion I I which, through the usual train of gears, drives the hour hand of the clock. A hub I2 '-is rotatably mounted on the shaft I0 and carries at one end a gear I3 which drives the escapement mechanism. This'end of the hub is connected to a spring Id, which spring is rotatable with the pinion II andfrictionally engages the side face of the gear, I3, thus enabling movement of the hands for setting the clock independently of the driving mechanism.

The opposite end of the hub I2 is formed with a peripheral flange I2a which cooperates with a centrally disposed extension .I2b of the hub to define an annular groove I3a. A main driving gear I5 is rotatably supported on the extension I2b and is held in abutment with the outer edge of the flange I2a by a washer I3b over which the end of the extension is turned back as shown at Ila, sufiicient clearance being maintained to permit rotation of the gearJ5 on the extension.

It will be apparent that'thehub l2, gear I3, and gear I5 provide a unitary assembly on the shaft III, which is 'frictionally connected with the pin.-

. ion through the spring II. The hub I2 latetained against movement axially of the shaft I ll,

away from spring Il, by means of a collar Ilb on the shaft, this collar forming an abutment for an internal shoulder I5a of the hub bore.

'- Movement of the gear I5 relative to the hub is limited by a projecting stud I5b on the gear I5, which is movable between the ends of an opening I50 in the peripheral flange I2a of the hub.

The gear I5 is connected to the hub through a spring I6 disposed in the groove I3a, one end 'of this spring being anchored in the gear I5 and the other end in the hub. with the foregoing arrangement, a secondary drive for the clock is substanprovided, which prevents a cessation or stopping of the timing mechanism during the interval when the main driving spring is,being stressed or rewound.

As shown in Figure 6, it will be evident that movement of the gear I5 in a forward direction to the limit of its movement will stress the spring IS in such a manneras to drive the hub I2 for a short interval of time.

There is also rotatably supported on the shaft III for independent movement at one end of the hub an armature I I. This armature comprises oppositely extending arm portions I8 and I9 which are deflected at their ends to form right angularly disposed projections 20 and 2I which define pole pieces cooperatively associated with the respective poles 22 and 23 of an electromagnet.

Each arm of the armature carries a. pivotally mounted pawl 24 having teeth at its free end .for engagement with the teeth of the main drivi 8 gear I5. The pawl. 24 is resiliently moved into engagement with the gear I5 by means of a spring 25 having one end in engagement with the-pawl and its other end engaging a stop pin 26. The pawls E l-24 permit free moveme of the armature in a counter-clockwise direction .relative to the gear I5, but on movement of the armature in a clockwise direction, the armature and gear I5 will move as a .unit.. Movement of the gear I5 in a counter-clockwise direction, when the armature is being moved in a counterclockwise direction, is prevented by means of a detent pawl 21. The pawl 21, however, will permit free clockwise movement of the gear I5.

Movement of the armature in a clockwise direction to actuate the timing mechanism is accomplished by means of a spring 28 having one end anchored, as at 29, to the armature,and its\ other end anchored, as at 30, to a bracket member 3| which is fixedly supported on the clock framework.

With the foregoing arrangement, it will be seen that when the armature is rotated in a counter-clockwise direction, the spring 28 will 45 be tensioned and the energy stored in this sprin may be'utilized to drive the clock mechanism for a limited interval of time. armature in a counter-clockwise direction is accomplished by energizing the electrc-magnet of the winding mechanism.

The electro-magnet is supported on a back plate 320i the frame structure by means of small projections 33 on thepole pieces 22 and 23, re-

, spectively, these projections extending through suitable openings in the back plate-and bein peened over. i

Movement of the,

Referring to Figure 1, it will be noted that the core of the. electro-mas'net comprises a plurality of iron laminations 3.4 having their .ends' extend-. ing into openings 35 in the faces of the poles 22 and 23 of the electro-magnet. core of the magnet isa coil winding 36 which in this instance is designed to operate on from 3.2 to 20 volts.

Surrounding the By energizing this coil: from a suitable source,

anism without any attention from the operator of the automobile.

It will be apparent that when the armature is moved in a counter-clockwise direction, the force of the main driving spring 28 becomes ineflective to drive the timing mechanism. It is durin this interval that the secondary drive, by means of the spring I6 comes into.play and drives the timing mechanism as previously described for a short interval, this interval being sufficiently long to permit tensioning of the spring 28 by movement of the armature, after which the main driving spring again drives the timing mechanism. The spring IE will be reenergized by movement of the armature in driving the timing mechanism.

Intermittent energization and deenergization of the coil winding of the electro-magnet is accomplished by a switch which is actuated in response to the movement of the armature. This switch comprises a pivotally mounted arm 31 which is supported for rotational movement on an intermediate pivot 38. This pivot is supported on a bracket 39 which is secured to the back plate 32. One end of the switch arm 31 is provided with a contact 40 which is arranged to engage with a contact 4| to open and close the circuit to the coil winding of the electro-magnet.

The contact 4| is secured to the outer end of a metallic strip 42, having its other end insulatingly anchored at 43 to the supporting bracket 39 Snap action of the switch is accomplished by moving it past a dead center position. The opposite end of the arm 31 from the contact 40 is provided with a V-shaped notch 44 for receiving the notched end of a link 45, the other end of this link being also notched, as shown at 46, to receive therein the free end of a spring member 41 which is anchored at its other end, as shown at 48, to the bracket 39. The bracket 39 also carries a stop member 49 for limiting movement of the arm 31 of the switch away from the stationary contact assembly.

It will be observed that as the switch arm 31 and link 45 are brought into alignment by movement of the switch arm, the spring 51 will be stressed. Further movement of the switch arm will cause the spring 41 and link 45 to pass the dead center position, and the spring 41 will force the contacts as and 4! to be engaged or disen-' gaged with a snap action.

Opening and closing of the switch is accomplished in response to movement oi. the armature by providing an angularly projecting arm portion at which is integrally formed with the switch arm Eli, this projecting arm portion at its outer endgbeing formed to define angularly disposed arms 3i and 52 which are so disposed as tobe engageable by a pin 53 on the armature.

It will be observed that when the contacts 40 and M are in separated position, when the switch is open, the arm is so disposed as to be engage'able by the pin 53 when the armature is moved in a clockwise direction and nears the limit of its movement, at which time it is desirable to rewind the driving mechanism. Movement of the switch to closed position will act to bring the arm 52 into the path. of travel of the pin 53, so that when the armature is moved in a counter clockwise direction by virtue of the electro-magnet being energized, the switch will again be opened to deenergize the electro-ma'gnet coil winding as the armature comes to its limit of movement in a counter-clockwise direction. It will therefore be evident that with this arrangement the driving mechanism is automatically and intermittently wound.

In the operation of the clock mechanism thus far described, it has been found that with a low battery or when cranking a car in the winter time, there is insuillcient voltage to sufiiciently energize the electro-magnet to move the armature in a counter-clockwise direction to the full limit of its movement in a counter-clockwise direction. In other words, instead of a full movement of the armature, the movement is only a partial movement, and while this movement will stress the main driving spring 28 a suflicient amount to continue the operation of the timing mechanism, the partial movement is not sufficient to cause an opening of the contacts 40 and 4| to deenergize the electro-magnet coil. Under these conditions, the electro-magnet will in a short time become overheated and may burn out or otherwise be damaged. Inorder to overcome this condition, an additional protective switch is provided in the energizing circuit of the electromagnet coil.

This switch comprises a U-shaped strip of bimetallic metal 54 having one leg anchored, as shown at 55, to form an electrical connection or terminal and secure the bimetallic strip to a base 55 of suitable insulation material. The free end of the strip of bimetallic material is associated with the free end of a contact member 51 which is anchored at its other end to the insulation base and forms a terminal 58. It will thus be evident that the bimetallic strip and contact element 51 are in" the circuit and carry current. The flow of abnormal current through the bimetallic strip will cause the free end portion of the strip to be flexed away from the contact element 51 and thus open the circuit. Snap-action of the contact members in opening and closing the circuit is accomplished by providing a spring member 59 having one end anchored to the insulation base and its other end deflected as shown at 60 to form a V which overlies the end of the bimetallic strip when the bimetallic strip is in contact with the contact element 51 and serves to delay the opening of the contacts until the forces deflecting the bimetallic strip are sufficient to overcome the action of the springs 59, whereupon the bimetallic strips snaps past the deflected end of the spring 59. Return of the bimetallic strip to a position in contact with the contact element 51 islikewise delayed by the deflected end of the spring 59 until sufficient force has-been built up to overcome the action of the spring 59, whereupon the bimetallic strip snaps past the deflected end of the spring 53 and engages the contact element 51 positively. In operation, the thermostatic switch will heat up and open its contact in about twenty seconds, and will close its contact, upon cooling of the bimetallic strip, in about one minute. In other words, the thermostatic switch provides a relatively quick opening and delayed closing of its contacts.

The thermostatic switch intermittently energizes and deenergizes the electro-magnet coil under abnormal conditions in such a manner that the coil is not overheated and there is no possibility of damage. As soon as normal conditions of excitation are established, the thermostatic switch will remain closed, and the automatic operation will then be by means of the switch which is opened and closed in response to the movement of'the armature.

The electrical connections to the clock are 75 shown schematically in Figure 1. A storage bat-' tery or other source oipower is indicated'at ll.

-As in the usual installation in automobiles, one

side of the battery is grounded at 82 and the other 'side is connected through a conductor 63 to a terminal $4 on the back plate, this terminal being insulated from the' back plate of the clock. A second irminal 65 is also provided and is grounded, as at 68, to complete the connection to the battery.

The energizing circuit of the electro-magnet coil is from the terminal through a conductor 86 to the terminal 58 oi. the contact element 51,

through the thermostatic strip 54 to the terminal. 55, the conductor 86 to one end of the coil 36,-

parent that the present invention provides an improved electrically actuated winding mechanism, whereby a clock of the spring driven type maybe automatically wound; wherein the winding of the clock is entirely automatic; an electric clock in which the electrical mechanism is pro- I have described in detail the preferred embodi-,

tected against overheating and possible damage; and in which novel secondary power means are provided for driving the timing mechanism for a short interval during which the main driving. mechanism is being energized.

It is of course to be understood that although ment of my invention, the invention is not to be thus limited, but only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

1. A clock comprising a rotatable drive shaft, a first member for driving the shaft, a second member rotatably mounted on the first member, saidmembers being connected for limited relative rotational movement, whereby the second member may drive the first member when the second member is rotated in one direction, a secondary spring connecting the members for rotating the first member when the second member is maintained stationary, means preventing rotation of the second member in the opposite direction, a main spring arranged for rotating the second member in the first direction, and mat. for intermittently energizing the main spring.

2. A clock comprising a rotatable drive shaft,

a first gear having a hub in driving connection with said shait, a main driving gear rotatably mounted for limited relativerotational movement on said hub, whereby the main driving gear may drive the first gear when the main driving gear is rotated in one direction, a secondary spring connecting said gears for rotating the first gear when the main driving gear is maintained stationary, means preventing rotation of the main driving gear in the opposite direction, a main spring for rotating the main driving gear in the first direction, and means for intermittently energizing the main spring.

3. A clock comprising a rotatable shaft, a first gear rotatable on said shaft, a friction connection between said gear and shaft, a second gear havlng a limited relative movement connection with the. first gear, whereby said second gear may drive the first gear after limited movement in one direction, a secondary spring connecting said gears for rotating the'first gear when the second gear is maintained stationary, means preventing rotation of the second gear in the opposite direction, means including a main driving spring for rotating the second gear in the first direction, means for intermittently energizing the main spring, an escapemen't mechanism driven from the first gear, and a time indicating member driven from said shaft.

4. An electric clock comprising a frame structure, a driving mechanism including a winding magnet having a coil adapted to be energized from an electric circuit, and a thermostatic switch for opening and closing the circuit to said coil with a snap action in response to an overload current for a relatively short .interval of time or a normal current for a relatively longperiod of time, said switch comprising a U-shaped thermostatic strip disposed in close proximity to said coil and anchored at one end, the other end being free for deflection, a fixed contact member having one end disposed for normal engagement by said free end, and a spring member delaying movement of the free end out or and into engagement with said contact, said contact and thermostatic strip being connected in said electrlc circuit. JOHN W. HOBBS.

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