US2145018A - Clock - Google Patents

Description

Jan. 24, 1939. R. L, TWEEDALE CLOCK Filed Aug. 13, 1930 2 Sheets-Sheetl A31. SOURCE INVENTYO'R.

Jan. 24, 1939. I R. L. TWEEDALE 2,145,018

' CLOCK Filed Aug. 13, 1930 ".2 Sheets-Sheet 2 IN V EN TOR.

MOZW

Patented Jan. 24, 1939 1 UNITED STATES PATENT OFFICE v CLOCK Ralph L. Tweedale, Dayton, Ohio Application August 13,

. 8 Claims.

This invention relates to electric clocks and has for its purpose the provision of a novel means and method of setting such clocks.

It is an object of this invention to provide in an electric clock, means for setting the hands controlled from a distance over the usual wires feeding the clock.

It is also an object of the invention to provide an electric clock having means for setting the hands to any of a plurality of positions.

It is a further object to provide a method of setting electric clocks from a distance.

Another object is to provide a hand-setter which is driven from the same source of power which normally drives the hands.

Another object is to provide an electric clock which is capable of being set to any hour indication.

A further object is to provide a novel master clock for controlling electric clocks.

It is also an object to provide a novel escapement mechanism which may be driven from a usual rotary motor and which imparts energy to a time keeping element such as a pendulum with a frictionless drive between the escapement and the time keeping element. 7

It is an object also to provide a clock escapement having a freely swinging time keeping element which may swing without having any frictional drag imposed upon it by the escapement.

It is a further object to provide a clock setting system in which a synchronous motor clock is set to various time indications by a master clock, located at a distance, over the usual line wires feeding the clock.

Another object is to provide a synchronous motor clock having means for striking the hours which are controlled from the master clock located at a distance.

A further object is to provide a clock and clock system of the type mentioned above which shall be relatively simple and shall avoid complex mechanism, especially at the secondary clock.

Other and sundry objects will appear from a study of the following description, the drawings, and the claims.

The preferred embodiment of the invention is illustrated in the accompanying drawings in which,

Fig. 1 is a diagrammatic or exploded View in perspective of a synchronous motor clock embodying my invention.

Fig. 2 is a detail view of a part of the resetting mechanism, being a partial section on line 2-2 of Fig. 1. I

1930, Serial No. 475,049

Fig. 3 is a wiring diagram of one embodiment of the invention.

Fig. 4 is a rear view of a master clock driving mechanism embodying the novel escapement mechanism, and

Fig. 5 is a wiring diagram of a modification of the clock setting system.

Synchronous motor clocks are gradually finding a wider use and sale on account of their greater accuracy when properly set, and on ac- 10 count of the comparatively low price at which an accurate clock can be manufactured and sold.

A big disadvantage of the synchronous motor clocks now in use, however, lies in the fact that whenever there is an interruption in the current 15 supply the clock stops. This results in great inconvenience because the clock must be set after every current interruption. This objection is keeping many people from using the electric clocks now on the market and it is an object of 20 this invention to overcome this dimculty and provide an electric clock which can be relied on to keep accurate time even though the current supply is often interrupted, temporarily.

Briefly the embodiment of the invention illusg5 trated contemplates setting the minute hand of a synchronous motor clock by a conventional heart-cam mechanism which is operated by a power take-off from the clock train at a relatively fast moving point in the train. For setting 30 the hour hand there is provided a notched disc connected to the hour hand and having a. single notch. A pawl is driven clockwise a predetermined distance, depending on the hour, to pick up the notch in the disc and if it is behind time 35 bring the notch up to the correct position corresponding to that particular hour. The pawl is driven by the same power take-off which drives the minute hand setter. The operation of the power take-oil? is controlled by an impulse sent 4 out from a master clock and super-imposed on the normal alternating current transmitted to the synchronous motor clock; The master clock may be located either at the power station with the master clock which regulates the frequency -45 of the alternating of the alternating current, or at a local point of distribution such as an apartment, school, oiiice building, etc., in which are located several synchronous motor clocks, or it may be the same master clock which regulates 50 the frequency of the alternating current, or it may be located at any point desirable.

The escapement mechanism of the master clock comprises a pair of impulse springs which have their efiective pivot points coincident with that 5 of the pendulum. One of the impulse springs is tensioned by a lever which is held in position by the friction of the spring acting in a substantially radial direction to the pivot point of the lever. This lever when thus held in spring tensioning position locks the escapement wheel. As the pendulum moves toward the spring it moves it back far enough to release the lever which swings out from under the spring which is then free to impulse the pendulum. The lever, having unlocked the escapement wheel, allows the wheel to turn far enough to move the opposite lever to spring tensioning position. The opposite lever also looks the escapement wheel when it has come to this position. The same cycle of operations is repeated by each lever and spring alternately. In Fig. 1 a self-starting synchronous motor 2 is driven from a suitable source of regulated alternating current, and includes the shading coils 4 and rotor 8. The rotor 8 drives a pinion 8 by means of shaft I8. Pinion 8 drives a gear I2 which drives shaft I4 carrying rigidly mounted thereon a gear I8. The broken away gears I8 represent any suitable reduction gear train which is well known in the art and is shown diagrammatically for sake of clearness. Gear train I8 reduces the rapid motion of pinion 28, fastened to gear I2, to a. relatively slow motion (one revolution per hour) of gear 22. Gear 22 is yieldably mounted on shaft 24 by means of a friction connection 28. Shaft 24 carries a heart-cam 28, a pinion 38, and at its outer end the minute hand 32, all rigidly mounted. Hour hand 34 is rigidly fixed upon sleeve 38 which is freely rotatable on shaft 24. Sleeve 38 carries rigidly at its rear end a disc 38 having a notch 48. Yieldably mounted on sleeve 38 by means of a friction connection 42 is a gear 44. The gear 44 is driven at a reduced rate (one revolution in twelve hours) from pinion 38 by means of the gears 48 and 48 mounted on shaft 58. Freely rotatable on shaft 24 next to disc 38 is a gear 52, carrying a pawl 84 adapted to engage notch 48. The gear 52 is yieldingly held in any position by the friction brake 58.

Pivoted to the frame 88 at 88 is a lever 82 carrying a roller 84 adapted to cooperate with the heart-cam 28 when lever 82 is raised. Lever 82 is raised by a cam 88 on shaft 88 and cooperating with a roller 18 on lever 82. The cam 88 is formed with a spiral rise portion in the first of rotation from the position shown and in the direction of the arrow in Fig. 1. The remaining 180 of cam 88 is a dwell portion which acts to retain the lever 82 in raised position and thus through the medium of cam 28 and roller 84 hold the minute hand 32 stationary during setting of the hour hand 34 as will be seen later.

Also mounted on shaft 88 is a mutilated gear 12 having teeth on only 180 of its periphery. The mutilated portion of gear 12 is arranged so that it passes the teeth of gear 82 during the same portion of counter-clockwise rotation of shaft 88 as that during which the rise portion of cam 88 raises lever 82. As the dwell portion of cam 88, turning counter-clockwise, comes under roller 18 the first teeth of gear 12 engage the teeth of gear 52 to turn it in a clockwise direction. Gear 12 carries a pin 14 on which is carried the inner end of a spiral spring 18 the outer end of which is mounted on a pin 18 fastened to the frame. The spring 18 is wound by counter-clockwise rotation of shaft 88 and its associated parts and is adapted to return them to a normal position determined by stop pins 88, 82 when shaft 88 is released as explained hereafter. Rigidly mounted at the forward end of shaft 88 is a drive gear 84. The drive gear 84 is driven from the power take-off gear I8 through a shiftable pinion 88. The pinion 88 is carried on a shaft 88 mounted on a lever 98. Lever 98 is carried by a sleeve 82 loosely rotatable on shaft I4 and is yieldably held against a fixed stop 84 by an adjustable spring 88. The lever 88 may be moved to engage pinion 88 with gear 84 by means of an armature 88 mounted on sleeve 82. The armature 98 may be attracted by an increased flux in the field structure of motor 2 as shown in Fig. 1 or it may be attracted by a separate electro-magnet I88 as shown in Fig. 5.

Referring to Fig. 2 it will be seen that the right hand edge of notch 48 is inclined from the radial so that the point of pawl 54 overlays the vertex of notch 48 when gear 52 comes to the position shown in Fig. 2 by a counter-clockwise movement. But when the gear 52 comes to the same position by a clockwise movement the pawl 54 will fall into notch 48.

Referring now to Fig. 4 there is shown the master clock driving mechanism comprising a weight motor I82 which is preferably of the self winding type. It is to be understood that the showing is merely diagrammatic and the motor may be of any type exerting a substantially constant torque reliably. The motor I82 turns shaft I84 which through the gear train I88, I88, II8 turns pinion H2 in a counter-clockwise direction. Pinion H2 is rigidly connected to escapement wheel II4. This wheel comprises a disc II4 on which is the raised portion II8 having the locking projections H8 and the raised cocking portions I28. Pivotally mounted on the frame at I22, I24 are a pair of levers I28, I28 carrying rollers I38, I32 adapted to engage the raised portions of the escapement wheel II4. Levers I28, I28 also carry rollers I34, I38 adapted to engage alternately a pair of impulse springs I38, I48 which are fastened to the clamp I42. The clamp I42 is carried on the frame and also mounts the spring I44 which supports the pendulum I48 carrying the impulse arms I48, I 58. The ends of springs I38, I48 are so shaped that when either roller I34 or I38 is raised the corresponding spring is tensloned and the lever is locked in raised position as lever I28 in Fig. 4. In this position the wheel H4 is locked by roller I32 abutting against the radial side of a locking projection 8. Stop pins I52, 154 are mounted on the frame to limit the inward move-- ment of springs I38, I48.

Referring to Fig. 3, I 58 represents the snail cam of a conventional striking mechanism which is mounted in the usual way on the master clock. The rack I58 is analogous to the rack of a conventional striking mechanism the only difference between it and a conventional rack being that rack I58 has twenty-four working teeth instead of the usual twelve. A gathering pin I88 is of conventional type and vmay be driven from a suitable motor (not shown) and which is released along with the rack I58 at every hour in a way that is well known in striking mechanisms. The rack I58 when in normal raised position as shown abuts against a bar of insulating material I82 carried by the resilient contact arm I84.

Arm I84 operates contacts I88, I88 connected to arms I18, I12 respectively. Arms I84, I18, I12 are insulated from each other by the insulating mounting I14. When rack I58 is raised the contacts I88 are closed but as soon as it is released and falls contacts I88 are closed and an instant later contacts I88 are opened. The contacts remain thus until the rack I58 is again raised to normal position when the reverse operation takes place. Contact I84 is connected to a wire I18 which feeds the secondary clocks I18 which are of the type shown in Fig. 1. Con-- tact I10 is connected to a wire I which leads from a source of alternating current. Contact I12 is connected by a wire I82 to a local source of direct current which is adapted to be at times super-imposed on the alternating current received. The other side of the direct current source is connected to the alternating current source by a wire I84. The other side of the alternating source is connected to the secondary clocks by a wire I88. The secondary clocks I18 are located preferably in a localized area such as an apartment, ofllce building, school, etc. The alternating current is supplied from a distant source supplying time regulated alternating current. The master clock and the source of direct current are located in the vicinity of the group of secondary clocks I18. In this way a local group of secondary clocks can be regularly set without requiring extra mechanism at the power house which furnishes the alternating current.

The operation of the system is as follows: The weight motor I02 through the gear train I08, II2 tends to drive the escapementwheel H4 in a counter-clockwise direction. In the phase position shown in Fig. 4 the pendulum is swinging to the right after having received an impulse from spring I38. On further motion of the pendulum to the right, impulse receiving arm I 50 will engage spring I40 and move it to theright a small amount. This will allow lever I28 to drop by gravity onto stop pin I80, disengaging pin I82 from the lochng projection II8. This allows wheel II4 to turn under urge of the motor I02 until the opposite projection I20 has moved lever I28 clockwise far enough to lock the wheel I I4 again by engagement of pin I30 with a projection II8. During this movement the left end of lever I26 moved spring I38 back to cocked position. Obviously as soon as lever I28 dropped, the spring I40 was free to act on the pendulum and move it to the left until spring I40 abutted against stop pin I54. On the following left swing'of the pendulum the same process occurs except that levers I28, I28 and associated parts take the opposite motions to those just described.

It will be noted that the only engagement of the pendulum with any escapement mechanism is the engagement between arms I48, I50 and springs I38, I40. During this engagement the arms and springs move through coinciding paths so that there is no frictional drag of one upon the other. This allows the pendulum to swing freely and eliminates any frictional retarding forces which vary with the conditions of lubrication, wear, etc.

The above described escapement mechanism drives in the usual way a dial train, not shown, which controls, also in the usual way, the release of the strike train motor and rack I58 and the position of snail cam I58. At a few seconds before each hour the rack I58 is released and the strike train motor is started. Contacts I 88 immediately close followed by the opening of contacts ingthe flux in the fields of all the secondary clocks I18. This condition is maintained for a definite length of time depending on the hour at which the master clock happens to be. I

when such an impulse of direct current superimposed on alternating current is received at the secondary clock (Fig. 1) the armature 88 is attracted. This moves arm 80 counterclockwise to engage gears 84 and 88. The motor is of course running at a constant rate because the source of alternating current is regulated in the well known way so that it generates equal numbers of alternations in equal time intervals. The shaft 88 is thus connected to the motor 2 and turns in the direction of the arrow at a constant rate. During the first half revolution of shaft 88 the cam 88 raises lever 82 and by engagement of pin 84 with heart cam 28 the minute hand 32 is brought around to the hour position from any position it should happen to-be in, friction connection 28 allowing the minute shaft 24 to be thus turned by the heart cam 28 without stalling the motor 2. After the shaft 88 has turned through one half revolution it will move through as many more twenty-fourths of a revolution as the number of the hour which the master clock indicates. This is determined by the length of time armature 88 is held against field 2 which in turn depends upon the duration of the impulse received. The duration of impulse is determined by the snail cam I58 (Fig. 3) which controls the amount of fall of rack I58 according to the hour indicated by the master clock. For example at one oclock the impulse will be of such duration that shaft 88 will turn through thirteen twenty-fourths of a revolution and at twelve oclock the impulse will be of such duration that the shaft 88 will turn through a full revolution (minus the necessary clearance allowances).

During whatever part of the second half revolution shaft 88 turns, gear 52 will be turned that amount by mutilated gear 12, since during the first half revolution all of the mutilated part of gear 12 passes by the gear 52. The ratio of gear 52 to gear 12 is one to two so that gear 52 is moved through as many twelfths of a revolution as the number of the hour. This enables pawl 54 to move from the twelve o'clock position (which is its normal position) to the position corresponding to the hour at the master clock. If the hour hand 34 should be slow it will be picked up along with disc 0 38 and be brought up to correct position by pawl 54. Obviously the possible correction at one oclock is only one hour while at twelve oclock it is twelve hours. It should be noted that the right faces of notch 40 and of pawl 54 are slightly slanted so that at twelve o'clock position as shown in Fig. 2 the pawl 54 will ride on the periphery of disc 38. One clockwise revolution of pawl 54 will bring its face just up against the right side of notch 40. 1

As soon as the impulse from the master clock ceases the armature 88 disconnects gears 84 and 88 and spring 18, which was wound during the motor driven rotation of shaft 88, will return shaft 88 and associated parts back to the position of rest with stops 80, 82 in engagement. When the last tooth of gear 12 leaves gear 52 the friction brake 58 holds gear 52 in normal position.

At I81 is an extension on shaft 88 which may be added to the setting mechanism already described for the purpose of striking the hours. It will be seen that shaft 88 forms an ideal drive for a simple striking mechanism since it turns at each hour through an angle corresponding to that hour. A disc I88 is carried rigidly by shaft I81 and has a series of twelve pins I90 arranged over 180 of its face. Pivoted at I92 is a trip lever I94. Also pivoted at I92 is another lever I96. A projection I 98 on lever I84 and extending under lever I96 enables lever I94 to lift lever I96 when turned counterclockwise but prevents movement of lever I96 when lever I94 is turned clockwise. Lever I94 is urged to a position with stop I98 against lever I96 by a spring, not shown. Lever I96 rests on a stop, not shown, in the position illustrated. When lever I96 is raised it lifts the striking hammer 200 through a connection 202. The hammer 200 when raised and dropped strikes the bar 204 which then emits the usual sound.

In operation as the shaft 68 turns, the first half revolution will bring the first pin I90 around to a position ready to operate the lever I94. As many pins I90 will pass the lever I94 thereafter as are necessary to properly strike the hour since the impulse received is of such duration that the shaft 68 turns through one half revolution plus as many twenty-fourths of a revolution as the number of the particular hour. When the impulse ceases, shaft 68 is turned back by spring I6 and the pins I90 turn lever I94 clockwise as they pass. This does not operate the lever I96, however, because it rests on the stop and the only effect is to tension the spring between levers I94 and I96.

Thus it will be seen that a simple mechanism may be added to the clock mechanism previously described which will enable the clock to strike the hours. Its simplicity flows from the fact that the means which determines how far the striking mechanism shall operate each hour is at the master clock so that only one determining means need be provided for any number of clocks. It will be understood of course that this striking mechanism may be omitted if it is not desired to have a striking clock.

In Fig. 5 is illustrated a modification which is adapted for use where the master is located at a point remote from the secondary clocks such as at the power station supplying the alternating current. It is also adapted for use in a situation where there may be one or more transformers intermediate the master and secondary clocks.

The contacts I66, I68 are controlled by the master clock in the same way as that illustrated in Fig. 3. If desired where the master clock is located at the power station the master clock may also be provided with mechanism for regulating the frequency of the alternators. Such mechanism is well known in the art.

The alternator supplying the clocks is illustrated at 206. An auxiliary alternator 208 is provided which generates a frequency different from that of the alternator 206. A transformer 2I0 supplies current to operate relay coils 2I2, 2I4. Relay coil 2I2 is connected to contacts I68 by a wire 2I6 and relay coil 2I4 is connected to contacts I66 by a wire 2I8. The armature 220 is arranged to be shifted back and forth by the coils 2I2, 2 and carries the contact bridging bar 222 which, bridges the contacts 224 when coil 2I2 is energized. The contacts 224 are connected in a circuit 226 which connects alternator 208 in parallel with alternator 206 to feed a line circuit 228 and a transformer 230. Connected to transformer 230 are the secondary clocks 232 similar to secondary clocks I18 except for a feature mentioned hereafter. One of the secondary clocks 232 is shown in diagram and includes the motor 2 and the electro-magnet I00.

The motor 2 is connected directly to the line while the electro-magnet I00 is connected to the line through a condenser 234. The difference between clocks 282 and I18 lies in the fact that the former have separate magnets to attract armature 98 instead of using the motor field for this purpose as in Figs. 1 and 3. The capacity of condenser 234 and the inductance of magnet I00 are so chosen that they are together responsive only to the frequency of alternator 208.

It will be seen that at each hour the contacts I68 close and coil 2I2 is energized. This throws alternator 208 onto the line and the frequency of this alternator is'super-imposed on the frequency of alternator 206. The magnet I00 then attracts the armature 98 and the setting mechanism illustrated in Fig. 1 operates in the manner previously described.

Any other suitable means for attracting armature 90 may be utilized, the two means shown being merely illustrative. It is well known that many ways are available for transmitting and receiving impulses over alternating current lines and the use of any such means is contemplated as within the scope of my invention.

It is to be understood that by the term "hand is meant any time indicating or recording member such as may be driven by a clock movement, this term being used only for sake of simplicity and clearness in the claims. Likewise the term line circuit is intended to include means for transmitting electric energy by means of radio waves.

The invention is not limited to the particular embodiments disclosedbut may take any form coming within the scope of the appended claims, the embodiments disclosed being for purposes of illustration only.

I claim:

1. In an electric clock having hour and minute hands and motive means operated from a line circuit, the combination of means for setting the hour hand to any one of a plurality of predetermined positions, and means placed into operation by a control impulse received over the line circuit for operating the setting means, the duration of the controlling impulse determining the position to which the hour hand is set.

2. In an electric clock system, a line circuit, time indicating hands, means energized from the line circuit for normally driving the hands, means for periodically sending over the line circuit impulses of different durations, and means called into operation by the receipt of an impulse for setting the hands to a position which is determined by the duration of the impulse.

3. A clock setting system including a secondary clock having time indicating hands and a synchronous motor driving the hands at a timed rate, a line circuit feeding the motor, a master clock at a distant point on the line, and means at the master clock for sending over the line impulses of different durations for setting the hands to positions determined by the duration of each impulse.

4. In an electric clock, an hour hand, a minute hand, timed motive means for driving the hands, means for setting the minute hand including a heart cam operatively connected with the minute hand, a driving member cooperating with the heart cam to move the minute hand to a predetermined position, and means including a spring biased spiral cam and a releasable power drive connection between the motive means and the spiral cam for causing operative engagement of the driving member with the heart cam, whereby the motive means of the clock moves the minute hand to a predetermined position.

5. In an electric clock, an hour hand, a minute hand, timed motive means for driving the hands, means for setting the hour hand to any of a plurality of predetermined positions, means for setting the minute hand including a heart cam operatively connected with the minute hand, a driving member cooperating with the heart cam to move the minute hand to a predetermined position, and means including a spring biased spiral cam and a releasable power drive connection between the motive means and the spiral cam for causing operative engagement of the driving member with the heart cam whereby the motive means of the clock moves the minute hand to a predetermined position, said spiral cam including a dwell portion whereby the minute hand is locked in position while the hour hand is being set.

6. In an electric clock, an hour hand, a minute I hand, timed motive means for driving the hands,

means for setting the hour hand including a notched disc operatively connected with the hour hand, a pawl capable of engaging the notch in the disc for moving the hour hand, a member freely rotatable about the same axis as the disc and carrying the pawl, a releasable power drive connection between the motive means and the pawl carrying member, and independently operated control means for engaging the drive connection and causing the pawl to move the hour hand to any of a plurality oi predetermined positions.

'7. In an electric clock, an hour hand, a minute hand, timed motive means for driving the hands, means for setting the minute hand, means for setting the hour hand including a notched disc operatively connected with the hour hand, a pawl capable of engaging the notch in the disc for moving the hour hand, a member freely rotatable about the same axis as the disc and carrying the pawl, a releasable power drive connection between the motive means and the pawl carrying member, and independently operated control means for engaging the drive connection and causing the pawl to move the hour hand to any of a plurality of predetermined positions, said drive connection including a mutilated gear whereby the setting of one hand is completed before the setting of the other hand is begun.

8. A secondary clock for use with a commercial line circuit comprising in combination time indicating hands, an electric motor energized from the line circuit, a time train for normally driving the indicating means from the motor at a timed rate, and setting means for the indicating means including mechanism responsive to an impulse of one certain character to bring at a predetermined time the indicating means to the same position from any of a plurality of positions in which the indicating means may happen to be and responsive to an impulse of another certain character to bring the indicating means to another position from any of a plurality of positions in which the indicating means may happen to be for bringing the clock to a correct time indication at a plurality of difierent times a day when its time indication diflers from correct time by any of a plurality of amounts.

RALPH L. TWEEDALE.

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