US3185874A

US3185874A - Adjustable cycle percentage timer

Info

Publication number: US3185874A
Application number: US263491A
Authority: US
Inventors: Charles A Hunt; Lewis E Schoonmaker
Original assignee: SESSIONS CLOCK CO
Current assignee: SESSIONS CLOCK CO
Priority date: 1963-03-07
Filing date: 1963-03-07
Publication date: 1965-05-25
Anticipated expiration: 1982-05-25

Description

y 25, 1965 c. A. HUNT ETAL ADJUSTABLE CYCLE PERCENTAGE TIMER Filed March 7, 1963 INVENTOR CHARLES A. HUNT LEWIS E. SCHOONMAKER BY ATTORNEYS United States Patent 3,185,874 ADJUSTABLE CYCLE PERCENTAGE TIMER Charles A. Hunt, Wolcott, and Lewis E. Schoonmaker,

Marion, Conn., assignors to The Sessions Clock Company, Forestville, Conn., a corporation of Connecticut Filed Mar. 7, 1963, Ser. No. 263,491

8 Claims. (Cl. 310-69) The present invention relates to a timing mechanism, and, more particularly, to a new and improved adjustable cycle percentage timer, a device which provides repetitive switching of two-phase cycles at a predetermined frequency. More particularly, the present invention relates to an adjustable cycle timer in which the relative duration of each of the two phases comprising a complete cycle may be readily, manually adjusted, and in which the frequencies of the cycles, themselves, the actual duration of the phases, maybe readily, manually adjusted.

The timer of the present invention essentially comprises an adjustable cyclical mechanism movable into either of two conditions or phases for predetermined durations, an electric motor of the type having bi-directioual starting and running characteristics for constantly driving the mechanism, and mechanical means in combination with the adjustable cyclical mechanism for periodically reversing the direction of rotation of the motor.

More specifically, the adjustable percentage timer mechanism of the invention includes an electric switch, a cycle plate supporting a pair of stop bars in an adjustably spaced relationship, a special actuating cam having a twophase camming surface, a motor reversing arm integral with the cam, and an electric motor for driving the actuating cam. In percentage cycling operations, the cam, in accordance with the principles of the invention, is

7 adapted to be driven in a first direction by the motor until the reversing arm strikes the stop bar to stall the motor and allow it to reverse itself to drive the cam in the opposite direction until it strikes the other top bar and repeats the cycle. The cam is especially shaped so that it maintains theswitch in two different conditions during the travel of the reversing arm between the two stop bars. In accordance with the invention, the reversing arm tends to be driven by the motor in a circular path of travel, which travel, however, is limited by the stop bars which, in addition to physically limiting the travel of the cam in a given direction, impart a reversing force to the motor upon impact of the reversing arm therewith. The overall cycle time will be determined by the mutual spacing of the stop bars.

At a predetermined point in the travel of the reversing arm between the stop bars, the especially shaped cam will timer may be adjusted by varying the mutual displace ment of the stop bars, while the durations of the individual phases may be adjusted relative to one another to achieve relative percentage times? by varying the displacement of the stop bars relative to the critical point.

For a more complete understanding of the present invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings, in which: 7

FIG. 1 is a side elevational View of a preferred embodiment of the adjustable cycle timer constructed in 3,185,874 Patented May 25, 1965 ice accordance with the principles of the invention with parts broken away to show details of construction;

FIG. 2 is a cross-sectional view of the mechanism of I FIG. 1 taken along line 2-2 thereof;

FIG. 3 is a front elevational view of a modified timer mechanism; and

FIG. 4 is a cross-sectional'view of the mechanism of FIG. 3 taken along line 44 thereof. 1

In FIGS. 1 and 2 of the drawing, a flat cycle plate represented by the reference numeral is provided with a pair of semi-circular arcuate slots 11 and 12 separated by a critical zone 12a. The cycle plate 10 is held in a spaced relation to a constant speed, electric motor 13, by spacer bars 14 and screws 15. The motor is a selfstarting, alternating current, synchronous motor having bi-directional starting and running characteristics. A typical motor of this category is described in greater detail in US. Patent No. 3,059,131, granted October 16, 1962 to J. J. Everard, et al. In the illustrated, preferred embodiment, the motor 13 is advantageously a Sessions Clock Company 8-4000 motor operating at l15 volts, 60 cycles per second, and is geared down through a suitable geartrain 9 to have an output of 20 rpm. at the power shaft 16. An electric switch 17, having a pivotable roller lever 18, is mounted to the cycle plate by a pair of nuts and bolts 19. The switch is typically a single-pole, singlethrow switch having contacts which are opened and closed 1 by the reciprocating movement of the roller lever 18.

A switch actuating cam 20, having an actuating surface 21 and a reversing arm 22 integral therewith, is fixedly mounted to the output power shaft 16 for rotation therewith by a rivet 16a ('FIG. 1) or other suitable means, such as force fitting (FIG. 4). The cam surface 21 is constructed with two contiguous active on and oif portions 21a, 2111 which cooperate, respectively, with the roller lever 18 alternately to open and close the switch contacts. The cam surface is said to have a transfer point 23, which is the point at which the cam surface 21 opens and closes the switch contacts depending upon its direction of rotation to transfer the switch 19 into its two phases, on and ofI,-for example. As may be clearly seen in FIG. 2, in a preferred embodiment of the invention, the reversing arm 22 is coincident with a radial line extending through the axis of rotation of the cam and the transfer point 23, and is adapted to be rotated by the shaft '16 in a predetermined circular path coincident with j the arcuate slots 11, 12.

A pair of

cylindrical stop bars

24, 25, having threaded necks 24a, 25a, of reduced diameter, are secured in the arcuate slots 11 and 12, respectively, by wing nuts 26 and washers 27 and may be adjusted to be locked in the slots 11 and 12 at varying distances from one another and from a dead center or critical position of the reversing arm 22, the position at which the cam 20 moves the switch into a different one of its two phases. Advantageously, the critical position of the reversing arm and the critical zone 12a are coincident, as are the arcuate slots 11, 12 and the circular path of travel of the reversing arm.

In operation, the electric motor is energized, and, due to its inherent, non-directional, starting characteristics, will start to rotate in either of two directions, clockwise, for example, and continue to rotate until the reversing arm 22 strikes the stop bar'25. The impact of the reversing arm with the stop bar 25 restrains or stalls the motor in the clockwise direction; however, the motor remains free to rotate in the unrestrained counterclockwise direction,

opposite to its initial direction of rotation and that of the reversing arm. Due to its inherent, bidirectional characteristics, the motor 13, will, in fact, reverse its direction and, thus, will change the direction of rotation of the cam to counterclockwise. Reversal of the motor 13 tends to be assisted by a small reversing force from the impact of posed by the

stop bars

24, 25, the cam will periodically open and close the switch contacts through the roller lever 18 as the cam passes through its transfer point 23.

It will be understood that, in accordance with the principles of the invention, the duration for which the switch contacts are made or broken, i.e., on or off, will be dependent entirely upon the displacement of the stop bars from the critical or dead center position and the speed of the output shaft 16. Thus, as shown in FIG. 2, the stop bar 25 which controls the duration of the off time is much closer to the critical or dead center position than the bar 24 which controls the duration of on time.

.Accordingly, each complete cycle of the cam will cause a greater proportion or percentage of on time than off time. The percentage of on time to off time, of course, may be varied merely by adjusting the displacement of the stop bars relative to the critical or dead center position between the slots 11 and 12. The overall cycle time will be determined by the circumferential displacement of the stop bars in the circular path and the speed of the output shaft 16.

Where it is advantageous and desirous to keep the overall cycle time constant, i.e., a fixed mutual spacing of the

stop bars

24, 25, but to vary the percentage of on and off times, the modification shown in FIGS. 3 and 4 may be employed. A separate rotatable circular plate 28 is provided and contains arcuate slots 29, 30, similar in shape and function to the slots 11, 12. Accordingly, a pair of

stop bars

34, 35, is secured to the plate 28 by wing nuts 36 to define a fixed cycle time or period. The plate 28 may be rotated relative to the critical or dead center position of the reversing arm so that the stop bars fixed to the plate 28 may be displaced relative to the critical position without altering their mutual circum ferential displacement or the overall cycle time. Advantageously, the rotatable plate 28 is mounted to a support plate 37, similar in function to the plate shown in FIGS. 1 and 2, by a pair of bushings 38, and a clamping button 39 which has a clamping screw 40 to clamp the plate 28 in a selected, adjusted position relative to the critical position of the reversing arm 22. Manual rotation of the plate 28 is facilitated by a projecting adjustment tab 41 located on its face. The elements shown in FIGS. 3 and 4, which are identical to those shown in FIGS. 1 and 2, have been given the same reference numerals.

Thus, it will be understood that the repeat cycle timer of the present invention provides an extremely simple and versatile, yet highly efiicient and reliable, timer for use in applications requiring adjustable, repetitive, two-phase timing cycle. The novel timer disclosed hereinabove has been found to be well suited for use in conjunction with automatic milking machines wherein the advantageous characteristics of adjustable cycle frequency and adjustable phase durations, adjustable percentage times, are most important and desirable. Moreover, the timer of the present invention, through the use of a minimal number of parts, affords great economies in manufacture and production without any sacrifice of accuracy, reliability or adjustability.

While the present invention has been described with respect to specific, preferred embodiments by way of illustration only, the scope of the invention is to be limited as set forth hereinafter in the appended claims.

We claim:

1. An adjustable, repetitive, cycle-actuating mechanism,

comprising (a) an electric motor having bi-directional starting and running characteristics,

(b) a power shaft operatively associated with said motor,

(0) output gear means operatively associated with said power shaft,

(d) an actuable mechanism having two conditions,

(e) a motor reversing arm rotatable in a predetermined circular path of travel toward, through and beyond a predetermined critical transfer position in said path at which position said actuable mechanism is trans ferred to one of its conditions,

(f) said reversing arm being fixedly mounted to said power shaft for rotation therewith in said predetermined circular path of travel,

(g) an actuating cam fixedly mounted to said power shaft and driven thereby to periodically initiate actuating movement in said actuable mechanism,

(12) said cam having a pair of contiguous active portions cooperating with said actuable mechanism to maintain said mechanism in one of its two conditions,

(i) said cam having a transfer point between said two active positions at which point said cam cooperates with said actuable mechanism to transfer said mechanism to one of its two conditions,

(j) a pair of stop surfaces disposed in said circular path of travel and limiting the rotation of said reversing arm in the direction in which said arm is being driven by said motor, said stop surfaces being mutually, adjustably positionable,

(k) each of said stop surfaces being adapted to cooperate with :said reversing arm upon impact therewith to stall said motor and to effect a force reversal of said motor,

(1) whereby said reversing arm is cyclically oscillated between said stop surfaces in cycles having predetermined frequencies which are a function of the speed of said output shaft and the mutual displace ment of said stop surfaces, and,

(m) said cam actuates said actuable mechanism for predetermined durations which are functions of the speed of said output shaft and the displacement of each of said stop surfaces from said critical position.

2. The mechanism of claim 1, which includes (a) plate-like supporting means for said stop surfaces,

(12) said plate-like supporting means defining a pair of circular arcuate slots,

(0) said slots being substantially coincident with said circular path of travel,

(d) said stop surfaces comprising stop bars,

(e) said stop bars being adapted to be adjustably supported in said arcuate slots,

(1) said slots defining a transfer zone between the ends thereof.

3. The mechanism of claim 2, wherein (a) said transfer zone is substantially coincident with said critical position.

4. The mechanism of claim 2, which includes (a) means for mounting said plate-like means for rotation relative to said critical position.

5. The mechanism of claim 2, wherein (a) said stop bars are substantially cylindrical and have threaded neck portions of reduced diameter,

(b) said neck portions are slidably and adjustably mounted in said arcuate slots by wing nut means. 6. An adjustable, repetitive, cycle-actuating mechanism comprising (a) an electric motor having inherent bi-directional starting and running characteristics upon connection to and energization by a voltage source,

(b) mechanical means for periodically reversing said 5 motor without altering the connection thereof to said source,

(c) output shaft means operatively associated with said motor and having less than one revolution in any direction between the reversals of said motor, and

(d) actuating means operatively associated with said shaft to move an actuable mechanism into at least two conditions between reversals of said motor.

7. A mechanism according to claim 6, in which (a) said mechanical means include a reversing arm and a pair of stop surfaces,

(b) said reversing arm being driven by said motor in a predetermined path,

(0) said stop surfaces being adjustably disposed in said predetermined path to limit the travel of and to reverse the direction of said motor,

(d) whereby said motor has a predetermined cycle time which is a function of the mutual displacement of said stop surfaces.

8. A mechanism according to claim 7, in which (a) said reversing arm is maintained in a fixed position with respect to said cam means,

(b) whereby the relative durations of actuation of the actuable mechanism are a function of the displacement of said stop surfaces.

References Cited by the Examiner UNITED STATES PATENTS 1,380,168 5/21 Whittingham 310--36 2,471,633 5/49 Lutz 200-38.1 2,632,888 3/53 Brookes et al 310-69 2,820,960 1/58 Witkowiak 31037 MILTON O. HIRSHFIELD, Primary Examiner.

Claims

1. AN ADJUSTABLE, REPETITIVE, CYCLE-ACTUATING MECHANISM, COMPRISING (A) AN ELECTRIC MOTOR HAIVNG BI-DIRECTIONAL STARTING AND RUNNING CHARACTERISTICS, (B) A POWER SHAFT OPERATIVELY ASSOCIATED WITH SAID MOTOR, (C) OUTPUT GEAR MEANS OPERATIVELY ASSOCIATED WITH SAID POWER SHAFT, (D) AN ACTUABLE MECHANISM HAVING TWO CONDITIONS, (E) A MOTOR REVERSING ARM ROTATABLE IN A PREDETERMINED CIRCULAR PATH OF TRAVEL TOWARD, THROUGH AND BEYOND A PREDETERMINED CRITICAL TRANSFER POSITION IN SAID PATH AT WHICH POSITION SAID ACTUABLE MECHANISM IS TRANSFERRED TO ONE OF ITS CONDITIONS, (F) SAID REVERSING ARM BEING FIXEDLY MOUNTED TO SAID POWER SHAFT FOR ROTATION THEREWITH IN SAID PREDETERMINED CIRCULAR PATH OF TRAVEL, (G) AN ACTUATING CAM FIXEDLY MOUNTED TO SAID POWER SHAFT AND DRIVEN THEREBY TO PERIODICALLY INITIATE ACTUATING MOVEMENT IN SAID ACTUABLE MECHANISM, (H) SAID CAM HAVING A PAIR OF CONTIGUOUS ACTIVE PORTIONS COOPERATING WITH SAID ACTUABLE MECHANISM TO MAINTAIN SAID MECHANISM IN ONE OF ITS TWO CONDITIONS, (I) SAID CAM HAVING A TRANSFER POINT BETWEEN SAID TWO ACTIVE POSITIONS AT WHICH POINT SAID CAM COOPERATES WITH SAID ACTUABLE MECHANISM TO TRANSFER SAID MECHANISM TO ONE OF ITS TWO CONDITIONS,