US1310375A - Clock system. - Google Patents

Description

jgg A9 A.F.PO0LL CLOCK SYSTEM.

ABPLICATION FILED OCT. 24. I917.

1,3 1 0,375. Patented July 15, 1919.

ARTHUR I. POOLE, OF CHICAGO, ILLINOIS.

CLOCK SYSTEM.

Specification of Letters Patent.

Patented July 15, 1919.

Application filed October 24, 1917. Serial No. 198,332.

To all whom it may concern:

Be it known that I, ARTHUR F. Poona, a citizen of the United States, and resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Clock Systems, of which the following is a specification.

My invention is an electric clock system and has for its object the improvement of systems of the prior art in which a master clock controls a plurality of secondary clocks through the agency of currents made or broken at certain predetermined intervals.

My improved system will be best under stood by reference to the accompanying figures, of which- Figure 1 is a diagrammatic view of the preferred embodiment of my system, and

Fig. 2 is a circuit modification thereof.

Referring particularly to Fig. 1, 1 is a master clock, which may be of any suitable construction, although I prefer to use a clock which is electrically wound. The master clock 1 is controlled by a pendulum 2, which is driven by a pair of pallets 3, driven by an escape wheel 4, fnounted on a shaft 5. The relation of the length of the pendulum and the teeth of the escape wheel 4 is such that the shaft makes one revolution per minute, and on said shaft is mounted circuit closing mechanism hereinafter to be described. The time between the operations of the circuit closing! mechanism is one minute, although any other interval of time may be used, such, for instance, as one-fourth of a minute, or even a period as long as fifteen minutes. In this latter event, the contact-making machanism hereinafter to be described would not be placed upon the escape wheel shaft 5, but upon some other portion of the clock mechanism.

The pallet 3 is supported on a shaft 6, which is connected by the usual crutch 7 to the pendulum. On the pallet shaft 6 and insulated from it is a spring arm 8, which is adapted to make contact with an arm 9, mounted on the escape wheel shaft 5 and rotating with it. Contact of the arms 8 and 9 will occur once for each revolution of the escape wheel shaft 5, and consequently in the specific structure herein described will occur once each minute. A suitable source of current, such for instance as a battery 10, is provided and the arms 8 and 9 are in an electric circuit as shown, said circuit including a relay 11, which is provided for the purpose of controlling the current sent out over the clock system.

From what has been described, it is obvious that the relay 11 will be energized once each minute. I will now describe the means by which the secondary clocks are driven and held in synchronism with the operations of the relay 11.

The secondary clocks are connected in parallel to the line wires and the line wires are supplied from the source of alternating current, such for instance as the ordinary current used for electric lighting purposes.

The secondary clocks each contain a small induction motor, whcih may advantageously be of the type used in induction watt meters, that is, a form in which a conducting disk is rotatably mounted in a shifting magnetic field. In the preferred embodiment of my invention shown, I have secured this shifting magnetic field by the well-known expedient of having an electromagnet with shaded poles. The secondary clocks contain in them mechanism to regulate the speed of rotation of the conducting disk and this mechanism is governed through the momentary breaks in the circuit which supply the induction motor with power.

To recapitulate, the general scheme of my clock system is to provide a series of secondary clocks driven by suitable continuously running motors and to synchronize these motors at periodic intervals with currents from a master clock. Synchronism is not attained by suddenly shifting the motors or the parts driven therefrom the amount of the error existing at the time the synchronizing current is sent out, but is accomplished by changing the speed governing means of the motor, so that the motor will run faster or slower in order to bring the parts moved thereby into synchronism. I will now describe the specific mechanism of the secondary clock.

The mechanism is shown in diagrammatic form only, since the parts constituting the secondary clocks are all so well known that a merely diagrammatic illustration of them will be sufiicient to inform those skilled in the art of the preferred means of practising my herein described invention. The motive power of the secondary clocks is provided by a conducting disk 12, which is arranged to rotate between the shaded poles of an electromagnet 13, which is connected between the line wiresl-l and 15. As before noted, these line wires are supplied by an alternating electric current from the mains 16 and 1'7. The relay 11 is provided with an armature 18, which is held by a spring 19 against a contact point 20, thereby maintaining a cur: rent supply on the line wires 14 and 15. Once each minute when the arm 8 makes contact with the arm 9, the armature 18 is attracted momentarily and this breaks the current on the line wires 14 and 15. However, the momentum of the disk 12 is suflicient to maintain it in rotation during the period of dei nergization of the magnet 13. The magnet 13 is provided with an adjustable magnetic shunt 21, which is provided with a screw arrangement 22, so that its distance from the poles of the electromagnet 13 may be changed. Obviously if the shunt 21 is approached to the poles of the magnet 18, the effective torque upon the disk 12 will be diminished and its speed will be accordingly decreased. The contrary will be true if the shunt 21 is withdrawn from the poles of the electromagnet 13.

I shall now describe the means for bringing the rate of rotation of the disk 12 into synchronism with the breaks in the supply current caused by the relay 11. The disk 7 12 is mounted upon a shaft 23, which is provided with a worm 24, which drives a gear 25 on a shaft 26, provided with a worm 27 driving a gear 28 on a shaft 29, which by suitable gearing 30 drives the hands 31 of a secondary clock. The arrangement just described may be taken as typical of any of the secondary clocks connected with the circuit. The disk 12 is so geared to the shaft 29 that when said disk is running at its normal rate, the time of one revolution of the shaft 29 is just equal to the interval between successive breaks of the supply current caused by the electromagnet 11. For instance, if the master clock 1 opened the line circuit once each minute, the shaft 29 would revolve once each minute also.

Mounted on the shaft 29 are two segmental gears 32 and 33, which each have slightly over half of their teeth cut away, as will be clearly shown by reference to Fig. 1. The shaft 29 and its rigidly attached gears 32 and 33 turns'in the direction of the arrow shown on the segmental gear 33. The segmental gears 32 and 33 are for the purpose of moving the magnetic shunt 2-1 as may be required and to this end I have provided a shaft 34, on which is rotata'bly mounted a gear 35, and also an arm 36 having rotatably mounted thereon .two spur gears 37 and 38. The spur gear 38 is adapted to be engaged by the teeth of the segmental gear 33 and not by the teeth of the segmental gear 32. The spur gear 37 meshes in both the spur gear 38 and the gear 35, and is adapted to be engaged by the teeth of the segmental gear 32, but not by the teeth of the segmental gear 33. The arm 36 is normally held so that the spur gears 37 and 38 are out of mesh with the gears 32 and 33, by means of a latch 39 having two armatures 40 and 41 rigidly attached thereto and urged against a stop 43 by a rctractile spring The armature 40 is adapted to be attracted by an electromagnet 45, and the armature 41 to be attracted by an electromagnet 46. The electromagnet 45 is connected in a shunt circuit around the electromaguet 46 and said shunt circuit includes a condenser 47 therein, or other equivalent means of splitting the phase. The electromagnets 45 and 46 are connected to the line wires 14 and 15.

Rigid with the gear 35 is a bevel gear 48 engaging a =bevel 49 on a shaft 50, on which is the screw 22 previously referred to. The arm 36 has a tail 51 rigidly attached thereto, and said tail is adapted to be engaged by a series of cams 52, 53 and 54 on the shaft 29. It will thus be seen that if the arm 36 is dropped, allowing the gears 37 and 38 to come in position to mesh with their coiipcrating segmental gears 32 and 33 that rota tion of the shaft 29 will revolve the shaft 50 first in one direction and then in the reverse direction, thereby raising and lowering the magnetic shunt 21.

The operation of the above described mechanism to maintain synchronism between the conducting disk 12 and the breaks of the line current is as follows: Assume that the normal condition of the secondary clock is such that the cam 52 is in engagement with the tail 51 at the time the current is broken. The latch 39 will be momentarily withdrawn from under the arm 36, said arm having been lifted slightly by the cam 52, and will return to its position shown in the figure before the cam 52 has passed from under the tail 51. As long as the secondary clock remains in this condition, that is, so long as the shaft 29 remains in synchronism with the movements of the latch 39 no change will be made in the position of the magnetic shunt 21 and the rate of rotation of the disk 12 will be undisturbed. Assume that from some cause the rate of rotation of the disk 12 is retarded, then when the latch 39 is withdrawn 'by the spring 41 as a consequence of the break in the line current the cam 52 will not yet be in engagement with the tail 51 and the arm 36 will drop, thus engaging the spur gear 37 with the segmental gear 32. During said engagement the shaft 50 will be rotated in a direction to withdraw the magnetic shunt 21 from the poles of the magnets 13 and the rate of the disk 12 will consequently be accelerated. This acceleration will continue, and the shunt 21 will continue to be drawn from the magnet 13 until the cam 52 lifts the tail 51, when the arm 36 will be retained by the latch 39. If the acceleration just given the secondary clock is not sufiicient to bring it into synchronism, at the next operation of the latch 39, the cam 52 will still be behind the tail 51 and the operation will be repeated. This shifting of the shunt 21 will continue until the shaft 29 is in synchronism with. the movements of the latch 39, which fact will be determined by the cam 52 being in engagement with the tail 51 at the time of motion of the latch 39.

In the event of the shaft 29 being ahead of the motion of the latch 39, that is, in the event of the conducting disk 12 running fast, the cam 52 will have passed the tail 51, when the latch 39 is operated. In this event the gear 38 will be engaged by the segmental gear 33 and turned until either the cam 53 or the cam 54 relatches the arm 36. Since the gear 35 will be turned in the reverse direction by the action of the gear 38, the magnetic shunt 21 will be approached to the poles of the magnet 13, and the rate of revolution of the conducting disk 12 will be diminished. This action will continue until the shaft 29 is brought into synchronism with the motion of the shaft, which fact will be determined by the contact of the cam 52 with the tail 51 at the time the latch 39 is operated.

It will be noticed that when the shaft 29 is corrected on account of its being slow, the correction is proportional to the error, that is, the more the shaft 29 is behind the motion of the latch 39, the greater will be the time during which the gear 32 will act on the gear 37. On the other hand, if the shaft 29 is fast. the correction will be inversely proportional to the error, that is, a small error will result in a large correction. This fact is not material since the action of the gear 38 will be to at once retard the disk more than the necessary amount, which will throw it to running slow, when the gear 37 will immediately start to correct the error and bring the shaft 29 again into synchronism. However, for the purpose of bringing the shaft 29 into synchronism when the shaft is but slightly fast, I have provided the auxiliary cam 53, which is a small angular distance behind the cam 52 and in the event of the disk 29 being but slightly fast the resulting correction will be but small.

It is obvious that the above described mechanism will always keep the disk 29 in wires. It is evident that any desired number of clocks having mechanism like the mechanism of my secondary clock just de scribed may be driven and controlled from the same line wires. The number of clocks which can be controlled in this way is simply a question of the current carrying capacity of the contacts 18 and 20, and these may be made to handle a current of any required size.

In some cases it may not be advantageous to allow the usual voltage of 110 volts to be on the clock lines, in which event all that is necessary is to provide a suitable transformer 57 between the break 20 and the line wires to reduce the current to any desired voltage.

My herein described system is very well suited for that class of time control which requires a considerable amount of power at the secondary clocks. Instances of this will be found in tower clocks where the hands are very large and are exposed to the snow and ice and hence require a comparatively large amount of power to move them. Another field in which my improved system can be used to advantage is in various systems of time stamps and workmens time recorders. In these installations, in addition to the usual clock hands the motive power is required to move printing apparatus of various kinds. Instead of having the entire load of moving this apparatus thrown on the secondary clock once each minute, I employ a continuously moving motor which is supplied with sufiicient power to overcome the heaviest load and provide means for synchronizing this motor and thus run it in unison with the currents sent out over the system from the master clock.

Another place in which my herein described system may be used to advantage is in running program clocks, that is, clocks which are required to ring electric bells at predetermined intervals. Inasmuch as my secondary clocks are in continuous motion as distinguished from the intermittent motions of secondary clocks of other systems, it is very easy to arrange the different contacts which are required to close thevbell ringing circuits.

It is obvious that the magnets 45 and 46, instead of being included in the circuit which furnishes the power to run the secondary clock motor might be included in a separate circuit and the power to run the motors in the various secondary clocks be taken directly from the light mains.

In Fig. 2 I have shown a circuit embodying this proposed modification. Reference to this figure will show that the magnet 13 is, as before, connected between the line wires 14 and 15. The magnet 45 controlling the latch 39, instead of being connet-ted to the line wires 14 and 15, is in a separate circuit which includes a battery 117 and a contact 120 of the relay 11, whose armature 18 is attracted at predetermined intervals as before. in each of the secondary clocks is actuated at the predetermined intervals. This arrangement is a somewhat obvious equivalent to the preferred arrangement as disclosed in Fig. 1. However, it may have some advantages in replacing an existing installation in which the wires connecting the various secondary clocks are not well enough insulated to permit the usual electric light current to be placed upon them. The secondary clocks can then be operated directly from the light mains and synchronized over the existing clock circuit.

Another advantage of my herein described system is that it may be made practically noiseless, thereby avoiding the objectionable click which occurs each minute in the prior art systems of minute jumpers.

lVhile I have described the synchronizing period in my system as a period of one minute, it is obvious that a much longer period between the synchronizing currents may be employed. The length ofthe synchronizing period is solely a question of the uniformity of the load and the current supply.

Many changes and variations may be made from the precise mechanism herein disclosed without departing from the spirit of my invention, since I claim:

1. In a clock system, the combination of a master clock, a secondary clock, line wires connecting the two, a continuously running motor, means to close the circuit intermittently, and means in said secondary clock to bringsaid motor into synchronism with said intermittent currents.

2. In a clock system, the combination of line wires, means to impress an intermittent current thereon, a secondary clock con nected to said line Wires, a motor in said secondary clock, time-indicating means controlled by said motor and means to bring said motor into synchronism with said intermittent currents.

3. In. a clock system, the combination of line wires, means to supply an alternating current to said line wires, means to break said alternating current at predetermined intervals, a secondary clock connected to said line wires, an alternating motor in said secondary clock, and means to bring the rate of revolution of said motor into synchronism with the breaks in said current.

4. In a clock system, the combination of line wires, means to supply an alternating current to said line wires, a master clock, means governed by said master clock to interrupt said alternating current at predetermined intervals, a secondary clock con- Thus the magnet 45' nected to said line wires, an alternating motor in said secondary clock, and means to bring the rate of revolution of said motor into synchronism with the breaks in said current.

5. In a clock system, the combination of line Wires, means to impress an alternating current thereon, a master clock, means governed by said master clock to interrupt said alternating current at predetermined intervals, a secondary clock, an induction motor in said secondary clock, time-indicating means driven by said induction motor and means to bring said inotor into synchronism with the interruptions. in said alternating current.

6. In a secondary clock, the combination of a continuously running motor, time-indicating means driven thereby, means to control the speed of said motor, line wires to which said secondary clock is connected, means to send a periodically recurring current over said line wires, and means to shift said speed-controlling means according as the rate of rotation of said continuously running motor departs from synchronism with said current interruptions.

7. In a clock system, the combination of line wires, a secondary clock, an induction motor, means for varying the speed of the same, time-indicating means, a gear connection between said induction motor and said time-indicating means, a member in said secondary clock actuated at predetermined intervals by current sent over said line wires, means to control the speed of said inductionmotor, a gear reversing device adapted to be connected to said speedcontrolling device, and means for bringing said gear-reversing device into action to bring the rate of revolution of said motor into synchronism with the interruptions of the current on said line wires.

8. In a secondary clock, the combination of a continuouslyrunning motor, speedgoverning means for said motor, an element actuated at predetermined intervals, a rotating shaft driven by said motor, a pair of segmental gears on said shaft and rotating therewith, and means for bringing the rate of rotation of said motor into synchronism with the movements of said periodicallyactuated member, said means being actuated by said segmental gears to control the position of said speed-controlling means.

9. In a secondary clock, the combination of a motor, time-indicating means driven by said motor, a speed control for said motor, a rotating shaft driven by said motor, a pair of segmental gears mounted on said rotating shaft, a second gear governing the position of said speed-controlling means, and means to bring said segmental gears periodically into mesh with said second gear.

10. In a secondary clock, the combination of a motor, time-indicating means driven by said motor, a speed control for said motor, a rotating shaft driven by said motor, a pair of segmental gears mounted on said rotating shaft, a second gear governing the position of said speed-controlling means, means to bring said gears into operative relation, and means rotating synchronously with said segmental gear to disengage said second gear from said segmental gears when the latter have reached a certain position.

11. In a secondary clock, the combination of a motor, time-indicating means driven by said motor, a speed control for said motor, a rotating shaft driven by said motor, a pair of segmental gears mounted on said rotating shaft, a second gear governing the position of said speed-controlling means, means to bring said gears into operative relation, and means to disengage said second gear from said segmental gears when the latter have reached a certain position.

12. In a secondary clock, the combination of an induction motor, a magnetic shunt adapted to vary the speed of said motor, a gear controlling the position of said magnetic shunt, a periodically-actuated element,

and means governed by said periodically actuated element for establishing an operative relation between said motor and said gear controlling the position of said magnetic shunt.

13. In a secondary clock, the combination of a rotating shaft, a gear on said rotating shaft, time-indicating means driven by said rotating shaft, a motor to drive said rotating shaft, a speed control for said motor, a periodically-actuated element, and means governed by said periodically actuated element for establishing a connection between said gear on said rotating shaft and said speed-governing means.

14. In a secondary clock, the combination of an alternating current motor, timeindicating means driven by said 'motor, a speed control for said motor, a rotating shaft driven by said motor, a pair of segmental gears mounted on said rotating shaft, a second gear governing the position of said speed-controlling means, means to bring said gears into operative relation, and means to disengage said second gear from said segmental gears when the latter have reached a certain position.

15. In a secondary clock, the combination of a rotating shaft, a gear on said rotating shaft, time-indicating means driven by said rotating shaft, a motor to drive said rotating shaft, a speed control for said motor, 'a periodically-actuated element, and means governed by said periodically-actuated element for establishing a connection between said gear on said rotating shaft and said speed governing means when said motor gets out of synchronism with said periodicallyactuated element.

In witness whereof I have hereunto subscribed my name.

ARTHUR F. POOLE.

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