US2163419A - Repeating alarm timer - Google Patents

Description

June 20, 1939. H WARREN 2,163,419

REPEATING ALARM TIMER Filed Sept. 29, 1937 Fig. l.

Insular! Inventor: Henry E. Warren,

9 His Attorney.

Patented June 20, 1939 PATENT OFFICE REPEATING ALARM TIMER Henry E. Warren, Ashland, Mass assignor to Warren Telechron Company, Ashland, Mass., a corporation of Massachusetts Application September 29, 1937, Serial No. 166,368

7 Claims.

My invention relates to timing devices of the type which is intended to produce an alarm or other signal at the end of a predetermined and preferably adjustable period of time subsequent to setting the timer into operation or to time other events, to count the number of revolutions of a motor, etc. Such a device is useful for example for timing processes and to notify an attendant when the time for completing: certain process has expired.

In carrying my invention into effect, I preferably employ a constant speed alternating current motor as the timing element of the device and utilize the alternating flux of the motor for sounding an alarm at the expiration of the time The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention, reference is made in the following description to the accompanying drawing in which Fig. 1 shows a perspective exploded view of the essential parts of a repeating alarm timer constructed in accordance with the present invention; and Fig. 2 represents a modified form of timer arranged to sound a continuous alarm at the end of the timing interval.

Referring to Fig. 1, I0 represents the stator of a self-starting synchronous timer motor, the rotor of which together with suitable reduction gearing is contained in the barrel II and from which a timer operating shaft I2, driven by the motonextends. Shaft I2 carries a gear I3 which may mesh with a gear I4 secured on a shaft I5. Shaft I5 is rotatively mounted in a bearing IE on a framework I1. Framework I1 is secured to the near end of a shaft I8 pivoted on its own axis in supporting structure not shown. Shaft I8 is of resilient material and has some torsional spring action and has secured to it, adjacent its far end, a magnetic bar 20, which comprises an armature with respect to pole pieces 21 and 22 projecting from the motor stator on opposite sides of the motor energizing winding 23. A spring I9 is provided which tends to rotate shaft I8 in a counterclockwise direction, retracting armature 28 away from its pole pieces and moving gear I4 to the right and out of mesh with gear I3. The axes of rotation of gears I3, I4 and frame I1 are parallel. Rotary motion of shaft I8 and the parts attached thereto is limited by a stop such as the stop pin 24.

pointer 28 is a time setting dial 32. normally stationary, it being held against rota- When the motor is energized from a suitable source of alternating current, designated at 48, the major portion of its flux traverses the rotary armature air gap and shaft I2 is driven at a constant speed. A certain amount of leakage flux 5 tends to cross through armature 20 between pole pieces 2| and 22 and the armature is attracted into contact with such pole pieces rotating shaft I8 clockwise and swinging shaft I5 slightly to the left of the position shown, and engaging gears 10 I3 and I4 in driving relation.

When the motor is deenergized the armature 20 is retracted as shown and the frame I'1 rests against stop 24 due to the action of spring IS, with gears I3 and I4 disengaged. As thus far 5 described, then, the motor performs two functions, as follows: It serves to drive gear I3 at a constant speed when the motor is energized, and it serves to engage and disengage gears I3 and I4 to and from driving relation as the motor is energo gized and deenergized.

Gear I4 is on a shaft with a gear 25 which meshes at all times in driving relation with a gear 26. Gear 26 is secured to a time setting shaft 21 which carries a pointer indicator 28 on 25 its front end and a collar 29 on its rear end. A spring 38 is provided for returning time setting shaft 21 counter-clockwise to an initial position when gears I3 and I4 are completely disengaged. Spring 30 is secured between collar 29 30 and some stationary structureso as to be wound up when shaft 21 is rotated in a clockwise direction by motor I0. It then serves to return the shaft 21 together with pointer 28, counterclockwise, to an initial poistion as soon as the motor 5 is deenergized, to disengage the clutch comprising gears I3 and I4. The initial position of shaft 21 is determined by a stop finger 3| projecting from the side periphery of gear 26 and which is rotated by spring 30 into engagement 40 with pinion 25 as a stop when gear I4 is disengaged from driving relation with gear I3. This initial position of time setting shaft 21 is then when stop finger 3| rests against pinion 25, and preferably ,wlih pointer 28 is pointing straight 5 up.

Concentric with shaft 21 and cooperating with Dial 32 is tion by friction. For this purpose the dial is 50 secured to a hollow shaft 33, carrying collars 34 and 31 on opposite sides of a plate 35 comprising one of the stationary supporting plates of the device. A resilient friction clutch member 36 is pressed between plate 35 and collar 31 with sufficient force to hold shaft 33 and dial 32 from rotation except when dial 32 is manually turned in an adjusting operation. For convenience in manually adjusting dial plate 32 it is made in the form of a gear wheel and meshes with a small gear 38 which is provided with a knurled thumb piece 33 for rotating the same.

The dial plate 32 is provided with a stop for pointer 28. In this instance I have shown the stop as including a contact device, although the contact feature may be omitted. The actual stop comprises a pin 40 of insulating material protruding from the side of dial 32 in the path of rotation of pointer-28. However, in front of stop pin 40 I have provided a pair of normally open resilient contact fingers 4| and 42 secured to the side of dial 32 at 43. These contact fingers are so arranged in the path of pointer 28 as it approaches stop pin 40 that their contact points will be pressed together as the finger 28 reaches stopping position. This contact device is illustrated as for the purpose of closing the circuit 44 of a relay 45 which may be utilized for any clesired purpose, such, for example, as the stopping of a process operation being timed by the timer mechanism.

The stopping positionof pointer 28 as determined by stop 40 is preferably opposite the zero graduation mark on dial 32 and the dial is graduated from this point in a counterclockwise di'- rection with suitable time indications, such as seconds, minutes or hours, depending upon what time range is desired and the rate at which the pointer 28 is normally driven by the timing motor II'I. For the purpose of the present illustration it may be assumed that the dial is graduated in minutes and that if the dial is set so that pointer 28, when in its initial or up-right posi tion, is opposite I on the dial, it will require I5 minutes for the pointer 28 to be driven to the zero mark and stopping point. It is important that when pointer 28 comes against stop 40 it will be positively stopped and will not rotate dial 32 through friction clutch 35, 36. 4

I make use of the stopping action of pointer 28 and the continued driving action of motor II] at the end of a time cycle to cause the armature 20 to produce a penetrating audible signal which is repeated every few seconds until motor I0 is deenergized. This audible signaling action will occur at the end of a timing operation and will'be explained when we come to that point in reviewing the manner of setting, operating and resetting the device for normal use.

Let it be assumed that the timer is to be used in connection with the development of photograph negatives, that it is desirable to leave the photograph negativw in the developing solution for minutes. The circuit of motor I0 is opened at a switch 46 which may, for sake of convenience, be located in the dark room. The timer mechanism may be located in the same or some other room. The attendant first sets dial 32 for 15 minute operation by turning the dial by means of knob 39 until it reads 15 minutes with respect to pointer 28. It should be observed that with motor In deenergized gear I4 will be demeshed from gear I3 and spring 30 will have rotated finger 3| against stop gear 25 so that pointer 28 will point straight up. The attendant then places his negatives'in the developing solution and closes switch 46 and goes about some other work. When the motor is energized, armature is attracted to polepieces 2| and 22, gear I4 is meshed with gear I3 and the motor starts into operation.

Pointer 28 is driven towards the zero graduation on dial 32 at such a constant rate as to reach this. point in 15 minutes, stop finger is rotated away from gear and spring is wound up. The direction of rotation of the gears I3 and I4 during this timing cycle are as indicated by arrows. At the end of 15 minutes pointer 28 is stopped by stop which blocks gears 26, 25 and I4 from further rotation. The driving action of motor I6 continues and gear I3 is rotated in such direction with respect to blocked gear I4 that frame I1 is forced to the right, rotating resilient shaft I8 counterclockwise and forcing armature 20 away from pole pieces 2|, 22. The motor is still energized so that armature 2|) now starts to chatter under the influence of the flux pulsations tending to draw it to the pole pieces and the opposing force tending to pull it away. The resiliency of shaft I8 augments this chattering action. As the armature is pulled further and further away the chattering becomes louder and louder until gears I3 and I4 havemoved far.

enough out of mesh to allow gear I3 to slip one tooth. This momentarily relieves the pulling away effect on armature 20 and it is-drawn toward the pole pieces. This action and the resulting audible noise cycle is repeated over and over as the teeth of gear I3 slip by the teeth in gear I4. As a result of this action there occurs a series of short penetrating sound signals each having a rising inflection, each such signal lasting for a few seconds and being almost immediately repeated. This notifies the attendant and he proceeds to stop the development process and as soon as convenient, he deenergizes the motor I0. As soon as motor I0 is deenergized, magnetic pull on armature 20 is relieved and gear I4 swings to full demeshed position with respect to gear I3. The driving connection between the motor and indicator 28 is interrupted. Spring 30 now returns stop finger 3| against gear 25 and pointer 28 to initial position and the device is ready for another timing operation.

The use of gear 25 as a stop for finger 3| is not considered to be essential but it is helpful in preventing any rebound action of frame I! which might tend to reengage gear I4 with gear I3. It will be noted that this stopping action of finger 3| against gear 25 is in a direction to tend to disengage gears I3 and I4. It will be noted that I have shown a shading coil 41 about a portion of pole piece 22. This is desirable to reduce magnetic hum of armature 20 when motor III is energized and when the armature is not intended to chatter. During audible signal operating motor I0 continues to run at constant speed. The frequency at which the audible signal will be repeated will depend upon the number of teeth in gear I3 and its rate of rotation. Generally, it will be desirable to have this signal repeat itself every few seconds and to arrange the speed of shaft I2 and the number of teeth in gear I3 accordingly. If shaft I2 runs at 1 R. P. M. and gear I3 has 20 teeth, the audible signal cycle will have a duration of three seconds. The gear ratio of the train beyond this point to shaft 21 will depend upon the time range desired on dial 32. It will be evident that the motor actuated audible signaling arrangement described may be' employed in any'motor driven gear train where it becomes desirable for any reason to give such a signal when the drive to a load through the gear train becomes blocked.

It will be seen that the arrangement is suchthat the entire operation of the timer is controlled by one simple switch such as the switch 46 in the circuit of the timer motor, and that this switch may be placed anywhere in the motor energizing circuit either adjacent to or some distance from the timer. Or, if more convenient, several such switches may be provided in series in the motor circuit so that the timer operation may be started by closing one switch 46 and stopping the operation by opening another switch 46 located in another room. All timer operations are performed in their proper sequence by the single time motor'as thus controlled and include starting a timing operation by closing the motor circuit, sounding a signal at the end of such operation, and, if desired, performing some additional controlling operation through the relay circuit 44 controlled by contacts 4 I-42, and stopping the audible signal, opening control contacts 4 I 42, and resetting the entire device for a subsequent timing operation upon opening the motor circuit.

It should also be observed that the timing operation may be stopped and the device reset at any time before pointer 28 reaches stop 40, should that be desired, by simply opening the circuit of motor III, in which case armature 28 would not produce the audible signal. The normal timer operating period may be increased or decreased within the time range of dial 32 by rotary adjustment of such dial and such adjustment may be made before setting the device into operation or duringits operation. The device may be used to perform a timing operation and automatically repeat such operation by including the normally closed contacts of a time delay relay shown at 35a in the circuit of motor I0 and connecting the coil of this relay in the circuit of contacts 4I42.

When the indicator 28 reaches stopping position.

the contacts are closed and relay 45a energized and the motor I0 deenergized. The electromagnetic clutch interrupts the driving connection at gears I3I4, indicator 28 returns to its initial position, contacts 4I42 open and the motor is again energized and repeats its operation. The time delay of relay 45a may be such as to allow the alarm to sound as well as to allow the timer to reset. The device may be made to start or stop or both start and stop in response to any event to be timed. For example, let us suppose that the switch 46 represents a thermostat switch responsive to temperature in a steam sterilizer, in which case the timer. would respond to the closing and opening of the thermostat switch and would give the time during which the tempera ture was uninterruptedly maintained above that corresponding to the setting of the thermostat and would sound an alarm if such temperature was maintained longer than necessary and the timer would reset without sounding an alarm if the temperature was not maintained long enough. Other uninterrupted processes or events may be timed in an analogous manner.-

Likewise, the device will be useful in many cases where the motor I0, instead of measuring time, measures speed or some other quantity, and the alarm is sounded after a certain number of revolutions independent of time. Hence, I do not wish to limit my invention to using a constant speed motor at II).

In Fig. 2 I have represented a modified form of imer employing several of the features of the timer of Fig. 1. Those parts which are similar in the two figures are indicated by like reference characters.

In Fig. 2 the clutch operating arrangement for shifting gear I4 out of mesh with gear I3 has been modified slightly because in this modification I do not depend upon the chattering action of armature 50 to produce a noise directly by striking its pole pieces. Instead, I mount a resilient bell clapper 5| on armature 50 and cause the hammer of this clapper to strike a bell 52 when armature 58 is set into vibration at the end of a time cycle. The outer end of armature 50 is connected to frame 53 by rod 54. Frame 53 is pivoted at 55 and is biased towards stop 24 by spring 56. The lower swinging end of frame 53 rotatively supports shaft I5. In this figure as in Fig. 1 the parts have been shown considerably 'spread apart and it will be understood that in actual construction, shaft I5 will be short and gears I4 and 25 will be close together and close to the bearing of shaft I5 in framework 53 so as to make a practicable construction.

In Fig. 2 gear 26 is not fixed on shaft 21 but is connected thereto through a friction clutch, a part of which is shown at 51. The dial plate 58 is fixed and has a fixed stop pin 59 for pointer 28. The initial position of pointer 28 is determined by a stop hand 60. Hand 60 is rotatively adjustable with respect to plate 58 but remains in any position of adjustment by reason of a friction coupling 8| between it and plate 58. Hand 68 has a projection 62 which catches and stops hand 28 when the latter returns to its initial position. against stop 62 when reset at the end of a timing operation. The distance of stop hand 60 from the stop pin 58 determines the time setting of the device.

The operation of this device is as follows. Stop hand 50 is set away from stop pin 59, a distance corresponding to the time setting desired. Spring 30 will rotate pointer 58 counter-clockwise against stop 62, when gears I3 and I4 are disengaged in any position of the stop hand 60. Motor I0 is then energized, armature 50 is attracted, and the bell receives one stroke of hammer 5|. Gear I4 is engaged in driving relation with gear I3. The motor starts into operation simultaneously and pointer 28 is driven from an initial position opposite hand 60, clockwise towards stop pin 59. Clutch 5! does not slip during this part of the cycle, and hence shaft 21 winds up spring 30. When pointer 28 is stopped at post 59 at the end of the time cycle, clutch 51 starts to slip and the torque transmitted through gears I3 and I4 is accordingly materially increased, which tends to swing frame 53 counterclockwise and move armature 50 away from its pole pieces against the pulsating magnetic attraction of the motor field. As a result, the bell clapper is vibrated and rings bell 52.

It is unnecessary that the gears I4 will move away from gear I3 far' enough to cause gear I3 to slip its teeth in order to cause a vigorous ringing of the bell. Of course, the friction at 51 may be made sufficient to block gear I4, in which case gear I3 will move gear I4 to'the right until the tooth in I3 slips by the adjacent teeth of gear I4 so as to periodically vary the outer limit of vibration of armature 50. This will cause some pulsating change in the sound of the alarm, as in Fig. 1. If such operation is desired, the friction clutch at 51 would not be essential.

When the motor I0 is deenergized, gear I4 is demeshed from gear l3 and the spring 30 returns pointer 28 to starting position against stop 62 of hand 60, wherever it may be set. This gear demeshing and pointer resetting action is desirable whether an alarm be included or not and such resetting operation may, of course, occur before pointer. 58 reaches post 59, should that become desirable. The hand 60 and pointer 28 are preferably painted different colors in order that an operator, who may wish to observe the device during its operation to see how much time is left during a timing operation, may more easily distinguish the pointer 28. Control contacts may be included on dial plate 58, as in Fig.

1, if that is desired.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An alarm timer, including a movable indicator, an alternating current electric motor, a driving connection including a pair of rotatively mounted intermeshed gears between said motor and indicator whereby the latter may be driven forward to indicate the number of rotations of said motor, a support for one of said gears pivoted on an axis of rotation parallel to the axes of rotation of said gears, resilient means tending to rotate said support to swing the gear carried thereby out of mesh with the other gear to interrupt said driving connection, a magnetic armature connected to said support and positioned to be attracted to the electric motor when the latter is energized to move said support against the action of said resilient means to establish said driving connection, the direction of rotation of the gears by said motor when the indicator is driven by the motor thereby also tending to rotate said support to swing the gear carried thereby out of mesh with the other gear, this last mentioned tendency plus the tendency of said resilient means being insufiicient to overcome the attraction of said armature to interrupt said driving connection when the motor is energized and the indicator is being normally driven, means between said gears and indicator for blocking further forward movement of the indicator after it has been driven forward by a predetermined amount, said blocking action and the continued operation of said motor causing the torque between said gears to increase by an amount suflicient to cause movement of the armature away from its attracted position and permit it to vibrate, said armature comprising a portion of an audible alarm which is operated by such vibration until the motor is deenergized.

2. In combination, a device to be-driven in a given direction, an alternating current motor, a driving connection between said device and motor, said connection including apair of gears, one of which is bodily movable from a position in driving relation with the other gear away therefrom to a position where said driving connection is interruptei.- the bodily movement of said gear from driving position to the inter- V rupted position being in the same direction in which said bodily movable gear tends to move by the transmission of power through said gears from the motor to the driven device when the latter is driven in said given direction, a pivoted support on which the bodily movable gear is rotatively mounted, a magnetic armature connected to said support and positioned to be attracted to said motor when the latter is energized to rotate said support and moveits bodily movable gear to driving position, resilient means tending to rotate said support and move its bodily movable gear to the interrupted position, said parts being so adjusted that when the motor is energized and the torque transmitted throughsaid gears is normal, the driving connection is maintained, and when the torque transmitted through said gears is in excess of normal, the armature is pulled away from the motor and is caused to vibrate and sound an alarm.

3. In combination, an alarm mechanism, a

device to be driven in a given direction, an alter nating current motor, a driving connection between said motor and device, including a pair of toothed gears pivoted for rotation on parallel axes, a frame pivoted to swing about an axis parallel to the axis of rotation of said gears and supporting one of said gears so as to move the same into and out of mesh with the other gear the direction of rotation of said gears being such as to tend to move the frame supported gear out of mesh with the other gear when the motor is in operation and driving said device in said given direction, resilient means also tending to swing said frame in the direction to demesh said gears, said alarm mechanism including a pivoted magnetic armature which is attracted to the motor when the latter is energized, a torsionally resilient shaft on which said armature and frame are both secured in spaced relation, the adjustment being such that when the motor is energised and the armature is attracted thereto, the gears are meshed in driving relation against the tendency of said resilient means and the normal driving action of said gears to move them apart and when the driving connection on the driven side of said gears is blocked, the motor continues to operate and moves said gears apart until their teeth slip with respect to each other, such slipping action of the gears being accompanied by a variable movement of the armature away from attracted position and intense vibration thereof productive of an audible sound which varies in intensity in cyclic relation to the slipping action of the gear teeth.

4. An alarm timer, comprising a time graduated dial, an indicator movable with respect to said dial, a synchronous motor, a driving connection between said motor and indicator whereby the indicator may be driven with respect to said dial to indicate the passage of time, said driving connection including disconnecting clutch means, electromagnetic means energized when the motor is energized for operating said clutch means to complete said driving connection, resilient means effective when the motor is deenergized to operate said clutch means to interrupt said driving connection, a stop on the indicator side of the clutch means for stopping time indicating movement of said indicator after it has been driven for a predetermined adiustable time, such stopping action and the continued operation of said motor causing clipping action of the clutch means, an alarm operated by the electromagnet means in response to such slipping action and the continued operation of said motor and a spring which is wound when the indicator is driven for returning the indicator to an initial position when the motor is deenergized.

5. An alarm timer comprising a time graduated dial, an indicator movable with respect to said dial and having an initial position with respect to said dial which is adjustable, a synchronous motor for' driving said indicator over said dial from such initial position to indicate the passage of time, stop means for stopping the movement of said indicator after it has been driven by said motor for a time corresponding to the position of initial adjustment with respect to said dial, a driving connection between the motor and indicator which includes disconnecting clutch means, electromagnetic means energized and deenergized when the motor is energized and deenergized for operating said clutch means to respectively complete and interrupt said driving connection, a spring between the clutch means and the indicator which is wound when the indicator is driven by the motor for returning the indicator to its initial position when the motor is deenergized, and an alarm operated by vibration of said electromagnetic means when said indicator is driven against its stop and the motor remains energized.

6. A timer comprising a movable time indicator, a synchronous motor, a driving connection between said motor and indicator whereby the latter may be driven by said motor at a constant speed to indicate the passage of time, said driving connection including a gear driven by the motor, a gear for driving the indicator, a shaft, and a pair of intermediate gears mounted on said shaft, one meshing with the motor driven gear and the other meshing with the indicator driving gear, a pivoted frame on which said intermediate gears and their shaft are mounted which frame may swing between a position where said gears are in mesh to complete the driving connection to a position where the gear-train is interrupted at the motor driven gear, a spring connected with said indicator which is wound up when the indicator is driven by said motor for returning said indicator to an initial position when the driving connection is interrupted, a projection on the indicator driving gear which is rotated into contact with its intermeshing gear on said frame as a stop for determining the initial position of said indicator, said stopping action being in a direction to urge the pivoted frame towards its gear-train interrupting position, and means responsive to the energization and deenergization of said motor for moving said frame to respectively complete and interrupt said driving connection.

7. An alarm timer comprising an indicator, a synchronous motor having an exposed magnetic field structure, a drive-connection between said motor and indicator for driving the latter at a constant rate to indicate the passage of time, said driving connection including a gear-train, a frame on which a portion of said gear-train is carried, said frame being pivoted for limited movement, a magnetic armature. connected to said frame and being positioned to be attracted to the field structure of said motor when the latter is energized, a stop for stopping the time indicating movement of said indicator after it has been driven by the motor for a predetermined time interval, said stopping action and the continued operation of said motor serving to cause relative movement of said frame and a retraction of the magnetic armature from its attracted position against the field structure to a position where the armature is caused to vibrate under the influence of the alternating flux of said field and set up an audible sound which continues until the motor is deenergized.

HENRY E. WARREN.

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