US2556095A

US2556095A - Timing device

Info

Publication number: US2556095A
Application number: US4991A
Authority: US
Inventors: Loewenstein Fritz
Original assignee: J E WORKMAN Inc
Current assignee: J E WORKMAN Inc
Priority date: 1948-01-29
Filing date: 1948-01-29
Publication date: 1951-06-05
Anticipated expiration: 1968-06-05

Description

June 5, 1951 IF. LOEWENSTEIN TIMING DEVICE Filed Jan. 29, 1948 gvwcm fo b FRITZ LOEWENSTEIN.

Clrtorneys;

Patented June 5, 1951 TIMING DEVICE Fritz Loewenstein, Newport, Del., assignor to J. E. Workman, Inc., a corporation of Delaware "6 Claims.

I This invention relates to a timing device and more particularly to an automatic device having 'a plurality of switches which may be actuated in any desired order and after any desired time delay.

There are many industrial operations which require a succession of steps to be performed in a certain order and for definite periods of time. Innumerable machines and processes are now controlled manually for lack of a practicalautomatio control device. It is, therefore, the principal object of this invention to provide a timing device for automatically actuating a plurality of control circuits.

It is another object to provide a timing device which is suitable for use on a great variety of machines and processes by reason of being easily adjustable as to time delays and sequences of operation.

It is a further object to provide a timing device that is inherently very accurate and stable in operation.

,,It is a further object to provide a timing device capable of providing both short and long time delays in the same cycle of operation.

In pursuance of these and many other objects which willbe apparent to those skilled in the art, I provide a lead screw driven at constant speed by a motor, preferably a synchronous motor. A follower is slidably engaged with a guide bar disposed parallel with the lead screw. The follower is pivotable about the axis of the guide .bar into engagement withv the threads on one side of the lead screw. Whenengaged with the lead screw threads, the follower is driven along the lead screw at a constant speed determined by the pitch of the threads and the speed of rotation of the screw. A plurality of fingers'p-rojecting from the follower are operative to actuate a plurality of switches disposed along the path of travel. Means are provided for adjusting the positions of the. individual switches thereby adjusting the time delay preceding their actuation. A limit switch actuated by the follower controls a sole noid which disengages the follower from the lead screw and allows it to return to the starting position for a new cycle of operation. In order to provide both long and short time delays in the same cycle of operation, the lead screw is driven by two synchronous motors, one being a low speed, and the other a high speed motor. One of the adjustable switches isthen connected to control the motors so that the lead screw is first driven by one, and after a definite time delay, driven by the other motor.

, Application January 29, 1948, Serial No. 4,991

Referring briefly to the drawings whereI show one embodiment of the invention:

Figure 1 is a side elevational view of the device with the enclosure cut away to show the relation.- ship of the elements; v

Figure 2 is a horizontal sectional view taken on the line 2--2 of Figure 1 looking in the direction of the arrows, showing the means by which the follower engages and disengages the lead screw; and

Figure 3 is schematic wiring diagram illustrating a manner of connecting the electrical elements of the device.

Referring now in greater detail to the drawings, lead screw in is journaled in bearings ll supported by enclosure [2. Driving motors l5 and I6 have different synchronous speeds and have a disk ll secured to their common shaft [8 by means of set screw it. A beaded collar 20', secured to lead screw H) by means of set screw 2| is driven by the disk H. The speed of rotation of lead screw H can bepreset over a range of values by adjusting the position of collar 20 on the lead screw. When collar 26 is set closer to the axis of disk. l'l, lead screw IE! rotates at a lower speed.

Motor l5 may be a high-speed motor, and motor l5, low-speed. When motor I5 is energized, it rotates at high speed and the rotor of motor is, being on the same shaft and not energized, also rotates at high speed. As will be subsequently described, means are provided to then de-energize motor 15 and energize 1ow-speed motor IS. In this way, lead screw l!) may be driven at high speedlor a definite period of time and then driven at low' speed for another period of time.

The motors l5 and it may be of the synchronous type so that the speed of rotation of lead screw to will be constant and accurately fixed by the particular motor energized. The

motors may be of the reversible type for reasons I ..tremity of the post is connected through spring 26 to the armature 2? of solenoid 28. When solenoid 28 is energized, guide bar 2! is rotated against the effect of biasing spring 24 in a direction such that follower 2B is moved away from lead screw H3; Spring 26 is stiff and provides ing screw 33.

positive, yet shock-absorbing, actuation of the guide bar. 7

The portion of the follower 20 which engages with lead screw I is in the nature of a half nut threaded to accommodate the threads on the lead screw. By this construction, the follower can be readily engaged with, and disengaged from,

the lead screw H]. A finger plate is rigidly secured to the follower 29 and is provided with a plurality'of fingers 31 extending on lines radial from the axis of guide bar 2|, as shown to advantage in Figure 2. The fingers 3| are operative to actuate a plurality of switches 32 which are disposed in an arcuate formation, there being one switch 32 for each finger 3|. The switches 32 are each in threaded engagement with a position- The positioning screws 33 are journaled at their ends 34 and 35 in the enclosure I2. Each positioning screw 33 is provided with a bevel gear 35, which is engaged by a"mati'n'g bevel gear 3'! controlled by knob 38 disposed on the exterior of the enclosure l2. By turning knob 38 the corresponding switch 32 may be positioned anywhere along the corresponding positioning screw 33. A rod 39 is provided in parallel relationship with each positioningv screw 33 and is operative to be slidably engaged by a groove 40 in each switch. Rods 39 prevent rotation of switches 32 about the corresponding positioning screws.

It is to be noted that when follower 2D is in engagement, with lead screw Hi, all fingers 3| are lined up with the actuating buttons 42 of switches 32, However, when follower 20 is disengaged from lead screw l0, fingers 3| are displaced from their original position in such a way that they cannot engage the actuating buttons 42. This structure is provided so that when the follower 20 is engaged with the lead screw and is traveling therealong, the fingers 3! will actuate the switches 32. Then when the follower 2B is disengaged from the lead screw, and the follower drops toits original position, the fingers will not engage the actuating buttons 42 of the switches 32;

The starting or zero position of the follower 20 is at the bottom of lead screw Ill. The portion of follower 23 which circumscribes the guide bar 2| is cut away at 44 so that post 25 will not interfere with follower 20 when the follower is in its zero position. When in the zero position, follower 20is in engagement with actuating button 41 of limit switch as. When follower 20 reaches the top end of lead screw l0, it engages and operates the actuating button 49 of top limit switch 50. It to be understood that the functions of

limit switches

48 and 50 may be performed by two of switches 32 disposed in corresponding positions at the bottom and top of their respective positioning screws 33. It is apparent that the device is thus adaptable to a great variety of applications and modes of operation.

The bottom limit switch 48 (or a switch 32 used in place thereof) may be of the normally closed type. The top limit switch 50 may be of the normally open type illustrated in Figure 3, having a holding solenoid 5|. As shown in Figure 3, electricity is supplied from source to actuating' solenoid 28 under the control of limit switches 48, 53' and manually operated switch 56. Source 55 also provides energy for motors I5 and I6 under the control of single pole, double throw switch 51.

' The operation of the timing device will now be described starting with the follower 2|! in the intermediate position shown in Figure 1. Follower 20 is in engagement with the threads of lead screw [0 and is moved upwardly at a constant speed. As the fingers 3| move past the switches 32, the latter are actuated by the corresponding fingers. The switches 32 will be operative to control whatever machine or process the timingdevice is used with. When the follower 20 arrives at the top of lead screw I0, the follower will depress actuating button 49 of top limit switch 50. It will be seen by reference to Figure 3, that under these conditions electricity is allowed to flow from source 55 through wire 60, armature 5! of limit switch 50, wire 62 through solenoid 28 and back to the source 55. Electricity also flows through wire 60, armature 6|, holding solenoid 5|, wire 64, lower limit switch 48 and back to the source 55. When current flows through solenoid 28, the solenoid is energized, drawing its armature 2'! inwardly and acting through spring 26 and post 25 to rotate guide bar 2|. The guide bar, being of polygonal shape, causes follower 20 to be disengaged from the lead screw II). when thus disengaged, the follower 20 is free to drop to the initial position at the bottom of the lead screw. It is apparent from Figure 2 that when follower 20 pivots about the axis of guide bar 20, fingers 3| are displaced to a position such that they are not in line with and cannot actuate the buttons 42 of switches 32. Therefore, when follower 29 drops to the initial position, the fingers 3! do not actuate switches 32.

When the follower 25 reaches the bottom or initial position, it hits actuating button 41 of bottom limit switch 48 thereby opening switch 48. During the time that follower 20 is dropping from the top position, holding solenoid 5| is operative to keep top limit switch 50 closed, thereby maintaining follower 20 out of engagement with lead screw l6. Then when follower 20 reaches the bottom and opens limit switch 48, the energy to the holding solenoid 5| is interrupted and armature 6| of limit switch 50 is allowed to return to its normally open position. Solenoid 28 is thus de-energized and spring 24 on guide bar 2| returns follower 20 to a position in engagement with the lead screw Ill. Follower 20 then moves longitudinally up the lead screw I0 and the fingers actuate the switches 32 in thepre-set order and with the pre-set time delay. It is thus apparent that the cycle of operation may be automatically repeated over and over. In the event it is desired to return the follower 20 to its initial position and temporarily keep it there, switch 56 may be closed manually. Solenoid 28 then holds follower 20 out of engagement with lead screw l0.

Switch 51 is provided so that either high speed motor l5 or low speed motor |6 may be employed at the will of the operator. If it is desired, to use a cycle of operation including a short time delay and subsequently a long time delay, switch 51 may be one of the adjustable switches 32. In the operation of the device under these conditions, lead screw l0 may be driven by high speed motor l5 from the time follower 20 is at the initial position until it reaches an intermediate position where a finger 3| actuates switch 51, de-energizing motor l5 and energizing motor I6. For the balance of the cycle, lead screw |0 will rotate slowly and follower 2|! will move at a correspondingly low rate. In this way, it is possible to obtain time relays in the, order of fractions of a second and hours in the same cycle of operation.

Another mode of operation, also within the contemplation of the invention, may be obtained where one or both of the motors l5 and I6 are reversible. In this event, limit switch 50 or one of switches 32 may be connected so as to reverse the direction of rotation of a motor instead of energizing solenoid 28. Then when the switch is actuated, follower will be driven down lead screw Ill instead of dropping down by gravity. Under this mode of operation, fingers 3| may engage and actuate the switches 32 on the way down as well as on the way up, or fingers 3| may be provided with pawls which actuate switches 32 on the way up but not on the way down.

While I have shown and described only one embodiment of my invention, it is to be understood that I am not to be limited thereto and that changes may be made in the invention without departing from the spirit and scope of the claims.

I claim:

1. An electric timing device comprising a lead screw and driving means therefor, a follower engageable with the lead screw for longitudinal movement therealong, a plurality of fingers extending from the follower, and a plurality of switches disposed in the path of said fingers when the follower is engaged with the lead screw, the switches not being in the path of said fingers when the follower is disengaged from the lead screw.

2. An electric timing device comprising a lead screw and driving means therefor, a guide bar parallel with the lead screw, a follower in slidable engagement with the guide bar and pivotable about the axis of the guide bar into engagement with the lead screw for longitudinal movement therealong, solenoid means for pivoting the follower into and out of engagement with the lead screw, a plurality of fingers extending from the follower, and a corresponding plurality of switches operatively disposed in the path the fingers take when the follower is engaged with the lead screw, but not in the path the fingers take when the follower is disengaged.

3. In an electric timing device, a lead screw and driving means therefor, a follower engageable with the lead screw for longitudinal movement therealong from an initial position, a limit switch disposed in the path of the follower for actuation thereby, solenoid means operative responsively to said limit switch to disengage the follower from the lead screw and allow it to return to its initial position, and a second limit switch" at the initial position operative responsively to return of the follower to control the solenoid and thereby re-engage the follower with the lead screw, whereby the cycle is repeated.

4. In an electric timing device, a substantially vertical lead screw and driving means therefor, a follower engageable with the lead screw for upward movement therealong, a limit switch disposed in the path of the follower for actuation thereby, solenoid means operative responsively to said limit switch to disengage the follower and allow it to fall to its initial position, and a second limit switch at the initial position, the solenoid means being operative responsively to the second limit switch to re-engage the follower with the lead screw.

5. In an electric timing device, a lead screw and a plurality of driving motors therefor, a common shaft connecting said motors, means secured to the common shaft for driving the lead screw, a follower engageable with the lead screw for longitudinal movement along the screw, and a switch disposed to be actuated by the follower during longitudinal movement thereof, the switch being operative to de-energize one of the driving motors and energize another.

6. An electric timing device for controlling a plurality of circuits in a pre-set sequence'after pre-set time delays, comprising a lead screw and a driving means therefor, a follower engageable with the lead screw, a guide bar parallel to the lead screw about the axis of which bar the follower pivots into engagement with the lead screw, and a plurality of switches disposed in the path of the follower and actuated thereby, the switches being arranged to be actuated in a pre-set sequence after pre-set time delays.

FRITZ LGEWENSTEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,237,329 Hamilton Aug. 21, 1917 1,812,454 Stockton June 30, 1931 2,034,275 Tarbox Mar. 17, 1936 2,152,631 Bohn Apr. 4, 1939