US2678095A - Resettable timing device - Google Patents

Description

y 11, 1954 B. CHAPMAN RESETTABLE TIMING DEVICE Filed Sept. 6, 1950 INVENTOR BERT CHAPMAN BY 8 6 AGENTE TO A. C. 60 CYCLE SUPPLY TO TERMINALS Y AND V 0F F/GJ.

Patented May 11, 1954 UNITED STATiTEi i A i'ENT OF FECE 3 Claims. 1 This invention relates to resettable timing devices wherein at the duration of a predetermined period of time, the time indicating components may quickly be reset to their original positions.

The apparatus is designed to drive two hands =or1pointers for indicating the amount of elapsed time, and means is provided for resetting such hands or pointers either manually or automatically. Two synchronous motors are provided .for the operation of the device. One motor is used for operating the device to accumulate time and for resetting the minor time increment shaft and the other motor is used for rapid reset operation of the major time increment shaft. Included in the mechanism are cam-operated contacts, together with exterior switches and wiring, for providing a means for resetting the device at the duration of a predetermined time cycle. Other contacts, similarly cam-operated, may be provided for operating a visible or audible signal to indicate the end of the said predetermined cycle. One of the aforementioned synchronous motors is geared to 2. seconds shaft and in the mode of the invention which is illustrated, moves a seconds indicator hand at a speed of one revolution per minute. By means 'of gearing, a seconds shaft drives a minutes sleeve according to a predetermined gear ratio corresponding to the major time increments which are desired. By means of theaforementioned contacts, the device may be started and permitted to run for a predetermined period of time which may be interrupted by manual operation of switches which are included in the circuit components. In other words, the circuit may be interrupted manually any number of times; however, at the end of the predetermined period, an automatic resetting operation will occur whereby the timing device is restored to its normal condition and the time indicators to their original positions.

The principal object of this invention to provide a r-esettable timer wherein the time indicating elements may be rapidly and automatically reset to their original positions without the use of clutches or gear shifting arrangements and the like.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a front elevation view of the timing 2 mechanism and includes certain cam-operated contact assemblies.

Fig. is a partial, sectional view of the drawing of 1 along lines 22 with certain components such as the synchronous motors shown in more detail and including one version of electrical wiring circuits which may be utilized in the device.

Now referring to the drawings, a synchronous motor 23 is secured to a plate 2? so that the motor shaft 361 projects through the plate 21 to carry a gear 3| fixed thereto. A second synchronous motor 2!, having a shaft 223, to which is fixed a gear 122, is spaced from the plate 2? so that gear 22 engages with another gear 24 fired to a shaft 25, which is journalled in plate 2"! and a second plate 25. The motor 22! is arranged so that, together with the gears 22 and 24, the shaft 25 rotates one revolution per minute; i. e. shaft 25 may be called a seconds shaft. A seconds hand 29 is fastened to the free end of shaft 25. Loosely journalled also on shaft 25 is a hub 32 to which is a gear 33 and a diiierential gear carrier 34. The gear 33 meshes with gear 3|. A hub it having an extension sleeve 32 is also loosely journalled on shaft 25, to which also is fastened a gear 38.

The hub 43 carries a gear 35% fixed to it in a manner to engage with another gear 3!; carried loosely on a stud 355 fixed near the periphery of the carrier 34 as shown particularly in Fig. 2. A gear 31, integral with gear 3%, is also carried by the stud 35 in such a way as to mesh with gear 38. A minutes hand 53 is fastened to the free end of the extension sleeve 32.

The gear ratios of gears 35, 3?, 38, and 36 may be chosen so that the hub iii and its sleeve 42 make one revolution for every sixty revolutions of shaft 25 or in any desired ratios.

When the switches S and T are closed so that the motor 2! is energized, and provided that the hub 32 is held from revolving, shaft 25 will be rotated at one revolution per minute via gears 22 and it, and hub it and sleeve 32 will be robated at a lesser speed via the gears 38, 31, 35, and 39. When either switch S or switch '1 is opened rotation of these components will cease since motor 21 is thereby deenergized.

Since motor 20 is normally deenergized, shaft 30 remains stationary; consequently, the hub 32 is held stationary via the engagement of gears 3| and 33, and the operation of the mechanism follows as described in the preceding paragraph. However, when motor 20 is energized the shaft 30 will rotate and gear 3| will drive gear 33 so that on the differential gear carrier 3 will revolve around gear 38 imparting rotation to hub and sleeve 42 via gears 35, 31, and 39 at a greater rate than is imparted to it from the rotation of shaft 25. Consequently the hub so and its sleeve 42 can be very rapidly reset to its original position.

In order to provide automatic resetting of the hub 40 (and sleeve 42) a cam 4| fixed to rotate with the hub Mi. The cam M is provided with a single drop-off (see Fig. 1) so that a follower C, which constantly rides the cam ll, will enter the drop-oft when the hub it and sleeve 42, together with the hand d3, are in their normal positions. In its normal position the follower C coacts with a contact strap D to close a circuit to a signalling device via connections SIG and, at the same time the contact straps A and B are kept in open circuit relationship (see Fig. 1). When cam 4| rotates, the straps A and B become actuated by follower C riding out of the drop-off to close a circuit through the connections Y-Y' of Fig. 1. Now referring to the circuit diagram of Fig. 2 it is readily ascertained that the motor 2t will be energized only when a switch R is closed and a circuit is established through YY'. Hence if the hub 40 is in any position except its norreal (or zero) position, the closing oi switch R will bring about rotation of hub 40 until its normal position is reached.

25 whereby a similar contact follower C controls the opening and closing of a pair of contact straps A and B to establish a circuit via connections X-X. Note that in Fig. 1 the shaft 25 is out of its normal position (zero position) while the hub ii) and sleeve 12 is in its normal position (zero position).

By way of illustration, let it be assumed that both shaft 25 and hub All (and sleeve 42) are in their normal (zero) positions so that circuits cannot be established through XX' and Y-Y respectively. Let it be assumed further that it is desired to time an operation wherein the minutes hub iii (and sleeve l2) will be automatical- 1y reset to its original position after the completion of a fractional rotation, and the seconds shaft 25 will be similarly reset to its original position. In order to operate the timer switch R will remain open and both switch S and switch T closed. Synchronous motor 2| thereby be energized and the time indicator hands 29 and 43 will indicate the elapsed time for the period of operation, at the end of which neither hand 29 or it is in its original position. Since switch '1 is opened at the end of the timing period, neither motor 2% nor 2! is energized. To reset the shaft 25 including hand 29, it is only necessary to open switch S and close switch T whereupon motor 2i becomes energized through connections EE-X and contact straps A and B. When the hand 29 reaches its original position the contacts A and i3 open as the follower C enters into the drop-oil portion of cam 25. To reset hub to (and sleeve 42) includin hand 63, it is only necessary to close switch B whereupon motor 2%? becomes energized through connections Y--Y and contact straps A and B. When hand 53 reaches its original position the contacts A and B open as the follower C enters into the drop-off portion of cam ll and motor 26 becomes deenergized.

As illustrated in Fig. l, the contact assemblies 44 and 45 respectively are provided with contact straps such as C and D whereby a signal may be electrically controlled to indicate whenever the will Similarly, a cam 26 is fixed to the seconds shaft v3 hands 29 and 43 are precisely in their respective original (zero) positions. Normally, the inertia of the gear reduction mechanism of the synchronous motors will be suificient in a device of this kind to prevent coasting beyond the original positions of the hands 29 and 43 during reset operations; however, it may be necessary in some instances to provide suitable braking means against motor-drift. A simple expedient may be provided in this respect by equipping switch T with a transfer point in its off position (not shown) whereby the motor 2i is connected across the alternating current line through a selenium oxide or copper oxide rectifier thereby providing electro-dynamic braking of a kind well known in the art.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

i. A timing device, comprising a first synchronous motor, a first time indicating shaft driven thereby and having an initial position from which. it is movable to indicate elapsed time, a second time indicating shaft also having an initial position from which it is movable to indicate elapsed time, a second synchronous motor, differential gearingconnected between the said shafts and the said second motor, first circuit means including a manual switch and means responsive to the movement of the first-named time indicating shaft away from the initial position for energizing said first motor to automatically restore said first shaft to said initial position while said manual switch is closed, further circuit means including a manual switch and means responsive to the movement of said second time indicating shaft away from the initial position for energizing said second motor to restore said second shaft to said initial position, and means for rendering said means responsive to the movement of said first shaft inoperative so as to enable said first synchronous motor to drive both time indicating shafts when elapsed time is to be accumulated.

2. A timing device comprising first and second time indicating each. having an initial po sition from which is movable to indicate elapsed time; a first synchronous motor gearcoupled to first shaft; a planetary gear dif ferential including two sun gears, a planet carrier, and planet gears meshed with both sun one 01 said sun being connected to said first shaft, the other sun gear being connected to said second shaft; a second motor gearcoupled to the planet carrier of said differential; i" t circuit means including a manual switch means responsive to the movement of the narued time indicating shaft away from the in lal position for energizing said first motor to automatically restore first shaft to said ini tial position while said manual switch is closed; it ther circuit means includin a manual switch and neans responsive to the movement of said second time indicating shaft away from the initial position for energizing said second motor to restore said second shaft to said initial position;

and means for rendering said means responsive to the movement of said first shaft inoperative so as to enable said first synchronous motor to drive both time indicating shafts when elapsed time is to be accumulated.

3. The timing device as set forth in claim 2 wherein the means responsive to the movement of said first shaft away from the initial position comprises a cam on said first shaft and a pair of contacts closed by the cam when said first shaft 19 6 prises a further cam on said second shaft and a pair of contacts closed by said further cam when said second shaft moves away from the initial position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,973,275 Babson Sept. 11, 1934 2,026,368 Warren Dec. 31, 1935 2,053,143 Frederick Sept. 1, 1936 2,198,632 Mullan Apr. 30, 1940 2,231,321 Butts et a1 Feb. 11, 1941

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