US2946902A - Repeat cycle timers - Google Patents

Description

July 26, 1960 P. A. HAGEN REPEAT CYCLE TIMERSV Filed Jan. 14, 1959 C Wt w* mw m V .fl mA .f/ Q s Hf C u. A. L.. .l l Fm w. M PB .mom .u u L 4.)B .Il M. 00m L (u Nw 0\ AML MC m 2m F7\|D J 2 d n United? Seres Pref O lREPEAT CYCLE TIMERS Paul A. Hagen, Baraboo, Wis., assignor, by mesne assignments, to The Gameweil Company, Newton, Mass., a corporation of Delaware Filed dan. 14, 1959, Ser. No. 786,747

12 Claims. (Cl. 307-14131) The invention relates to a functionally and structurally improved and simplified timer that will repeat a selected time cycle, each cycle comprising an interval during which one or more switches are closed and :a second, shorter interval during which the switch or switches are open. A second set of switches may be arranged to operate in the reverse order.

The invention is believed to be novel in that the load controlling and timer motor controlling switch is moved between a fixed and an adjustable stop.

Another novel feature of the invention is its self-adjusting reset spring: yas the timing interval is lengthened and the distance the switch must travel during reset is increased, the reset spring is wound tighter and its initial torque is thereby increased. The increased torque returns `the switch at a faster rate at the longer time settings. Thus, reset time tends to be constant over a range of timing intervals. For shorter intervals the initial torque of the reset spring is lowered; for longer intervals the initial torque of the reset spring is increased. The characteristics ofthe spring can be chosen so that the variation in the initial torque will cause the reset time to be approximately constant for any selected time setting.

In a modified form of the invention, the outer end of the reset spring is fixed. As the distance the switch must travel during reset is increased with an increased setting on the dial, the spring torque is greater at the end of a short reset interval than at the end of a long reset interval. 'This tends to make the duration of the reset interval proportional to the timed interval. The spring tension is identical at the beginning of all resetintervals, regardless of timing duration, but at the end of a long distance reset interval the spring is unwound more and the tension is less. The average reset torque decreases as the timed interval (and the reset distance) increases; thus causing the reset time to be greater when the timed interval is greater. If the spring characteristics are properly selected the reset interval will be proportional tothe timed interval.

The preferred form of the invention employs the increasing torque feature. As the timer is set to time a longer interval and the distance the switch travels during reset is necessarily increased, the torque of the reset spring is also increased. When the timer is set to time a shorter interval, thereby decreasing the distance 4the switch travels during both the timing interval and the reset interval, the torque of the reset spring is also decreased. This tends to make the reset interval constant for various settings of the timer dial. Spring tension is always the same at the end of the reset rotation, regardless of timer dial setting. The modified form of the invention employs the proportional timing feature. That is, the duration of the reset interval is proportional to the duration of the timed interval `at all settings of the timer dial. At the beginning of the reset interval the torque of the reset spring is always the same, regardless of timer dial setting.

The invention greatly simplifies presently known apparatus by providing an instantaneous make and break switch in the circuits established or broken at the end of each timing interval. No external relay is required to boost the capacity of the timer contacts. In many timers, the time determining element moves at a fixed rate of speed over a fixed path and makes or breaks contacts at each end of the path. The present invention rotates a snap acting switch over an adjustable path; at the ends of the path the switch is actuated to provide rapid opening or closing of the circuit. Thus, arcing is not a problem.

Known timing devices usually employ cams, cam followers, and electric contacts to control a load device and the timer motor. The invention eliminates the cams and cam followers and utilizes a snap acting switch :to control the external load device and the timer motor.

Known -timers also employ a solenoid operated clutch mechanism to disengage the camshaft from the motor during reset as the motor has inertia that would prevent rapid reset if it were left engaged during reset. The present invention eliminates the solenoid and employs a simple clutch lbuilt into the standard motor.

The switching arrangement used in the invention is superiorto known `arrangements in its foolproof operation. The switch is of the reset type and is actuated at the end of its travel in either direction and remains in that condition until it is carried to the other operating point where it is again actuated. During travel in either direction there is nothing to cause it to switch accidentally.

Another desirable feature of the timer is that it may be reset during any portion of its timing cycle by momentarily opening the circuit to the motor. The timer resets itself and starts timing a fully timed interval as soon as power is restored. This feature is important when the device controlled by the timer must not be energized until a full interval has elapsed after power is restored after a power failure.

The timer switch may be connected to transmit a short pulse at the end of the -timed interval. The duration of the short pulse is in one embodiment substantially constant for various timer settings and in another embodiment is proportional to the timed interval. In either form it corresponds to the full time required for the device to reset. The differences in resetting time are obtained in the first form by winding the reset spring tighter for Ithe longer timing cycles, and in the second form by anchoring the reset spring to a fixed support.

The short pulse occurring at timed intervals is useful in a large number of timer applications. One application of the invention is in conjunction with a photographic vslide changer projector in wlrich the viewing interval is vtimed by the timer. At the end of the viewing interval the timer energizes the slide changer solenoid injecting a new slide and ejecting the viewed slide. The invention will be illustrated with respect to this use but is by no means restricted to this usage.

The invention will be described with the aid of the accompanying drawings in which Figure 1 shows the invention, diagrammatically, in perspective.

Figure 1A shows one portion of the invention in a second form.

tFigure 2 is a section taken along line 2 2 in Figure 1.

Figure 3 is a section taken along line 3 3 in Figure 1.

Figure 4 shows the timer circuit during the timing interval.

Figure 5 shows the timer circuit during the resetting interval.

Figure 6 is a diagram showing the timer circuit and a slide changer.

In the drawings, a synchronous motor `1 drives a pinion 2 `through reducing gears (not shown) in gear box 3 which vforms a part of motor housing 4. A unidirectional clutch arrangement 5 (not shown) is built into the gear-box 3 and permits the motor to drive the main 'timer sha'ft7 through the gear 6 keyedthereto'. Shaft '.7 cannot. rotate the motor in the reverse directionV because ofthe one-way clutch 5. Y

As .the motor 1 drives the main timer shaft 7 in -a counter clockwise direction, as viewed -from the dial 1'3, the reset spring 10 is wound tighter. "The inner end of spring is anchored to shaft 7 and the outer end 11 ,of spring 11i is attached to movable stop 12.'.Whern power is removed from motor 1 reset springrlt) -will rotate shaft 7 in a clockwise direction.

- Main timer shaft 7 is thus driven in one direction 'at a slow rate of speed determined'by the speed of .motor 1, gear reduction 3, and the size of pinion 2 and reducing gear 6. Shaft 7 is driven in the opposite direction at Aa higher rate of speed` determined by reset spring r11i and the friction and inertia of the rotating parts.

Atiixed to timer shaft 7 is an L-shaped bracket 1S to -which a 'snap 'acting switch 16 is aixed. As shaft .7 oscillates it carries with it bracket and switch 16.

'Switch 16 is of the reset type and has an actuator .17

having both ends .17', 17 exposed; Asthe switch is rotated `in either direction it moves until the ends 17'., `'1'77 of its actuator come in contact alternately with .a fixed stop 18 or the movable stop 12. Gradual movement of actuator .17 Vcauses additional stressing of .the prestressed member within the switch 9 until the contacts snap into the reverse position. They remain in .this position until actuated to theother position. Y

The time it takesmotor 1 to rotate switch`16 vfrom the movable stop 12 to the iixed'stop 1S determines one ,period ofthe cycle; the time it takes reset spring 10 toreturn `switch 16 from xed stop 13 to 'movable stop 1-2 determines Ythe second'period of the cycle. V"The second period can be made almost constant regardless of the duration of the tirst period of the cycle because movable stop 12 winds reset spring 16 tighter as .the settable timing period -is increased. The. additional torqueof resetspring 10 resets switch 16 over a greater arc in approximately .the same interval of time. When the rst Vportion of the cycle is adjusted to be of short duration, movablestop 12 partially unwinds reset spring 1t); the decreased ltorque 'resets switch 16 in approximately the same interval.

`In a second form of the invention shown in Figure .1A the outer end 11 of spring 1d maybe atiixed to a post 19 permanently attached to a frame member. The torque of reset spring il@ .thus does not vary as the interval is changed. The reset interval is thus substantially proportional `to the settable interval.

The .duration of the one period is preset by turning knob 8 to thegraduation markedon dial 13 correspond- 'ing to the desired'interval.

The dial 13 is calibrated in units of timecorresponding to on time, and linear. Various motor speeds are available to give a range of timing limits.

VThe timer is made to time repetitively by connecting motor 1 to a power source L1, L2 through .the timers own switch contacts, as shown in Figure 4.- Onealine from the power source L2 is connected to the common terminal C of the timerV switch 16. One motor .lead 21is connected to the normally closed contact vterminal NC of.v the timer switch. The remaining motor lead 19 Yis 'connected to the L1 line of the power source. A circuit ltothe motor is thus established. The timed interval ensues while motor `lirotates switch 16 counter clockwise until actuator 17' is brought up against iixed stop 18; Figure l. Thetravel of-.actuator 17 stops but switch 16'continues lin a CCW direction until the snap :action of the. switch opens .the circuit betweenfcontact terminals C and NC, asshown in Figure 5. Motor 1 is thusfdeenergizedvand reset spring ,10 quickly :rotates ai switch 16 in a CW direction. During this resetting interval power ows out on the normally open contact terminal NO to the load.

The resetting interval ensues While reset spring 10 rotates switch 16 in a CW direction until actuator end 17 is stopped by movable stop 12 and switch 16 continues until the snap action of the switch opens the load circuit and closes the motor circuit. The motor turns shaft 7 and switch 16 in a CCW direction and the cycle is repeated until power is removed. Y Y

The invention is illustrated in Figure 6 in conjunction with a photographic slide changer. As explained above one power line L2 is connected to the common switch terminal C. `Motor lead 21 is connected to the normally closed contact terminal NC and receives power through the common contact arm from terminal C and line L2. A momentary type pushbutton switch 20 is connected .in .linefZl .so .that the circuit may be brokenmomentarily. Motor lead 1'9 isV connected to line L1.

The slide changer shown in igurez consists of a solenoid coil 22, a plunger 2.3, a return spring 2.4, a biased iinger 2.5, a new slide 2.7 and a viewed slide 28. The solenoid coil Y22. is connected as a load between the normally open contact'NO and .line L1. When Ypower is appliedat L1, .1.2, the motor is energized andtiming .commences. `When motor ihm moved switch 16 to xed stop '1S and caused actuator .17 to be depressed, the actonof switch 16 snaps .the movable arm and contact into VContact with the normally open contact NO. Power now 'iio'ws from L2, through themovable arm and contact 7C, through normally open contact NO, and through the load device '22 'to the'Li. terminal. lPower flows in this external load circuit `while the .timer 'is resetting. Normally, the resetting interval is in the Vorder ofone second or less. .During lthis time .power energizes coil 22 of the slide changer causing the re placement .of the viewed slide 28 with a new slide 27. When the switch 16 has been rotated by reset spring 10 suici'ently to permit actuator 17" yto be Adepressed against `movable stop 12 the snap action of the switch V16 change'sithe position ofthe movable arm and contact to that shown in Figure 6. The external load circuit is deenergized and the magnetic attraction of coil 22 for plunger 23 decays allowing spring 24 to draw plunger 23 to the left thereby releasing .finger Z5 for movement Yof another slide when solenoid 22. is again energized. The movable arm 'and contact closes the NC circuit to motor 1 starting 'another timed interval.

The duration ofthe timed interval is readilyadjusted Y by rotation of knob 8 over .calibrated `dial 13. Knob vspring 10. to reset the timer to zero. Timing does not start again until the Vswitch 20 is closed supplying L2 power tothe motor. The switch 16 is not affected by 'this operation and the .duration of the timed interval is increased. Y

In the application of the timer shown in Figure 6 the viewing time Yis set on the dial 13; at the end of each viewing interval an electric pulse of short duration is sent to the slide changer solenoid YZ2. The operation of vthe .solenoid ejects the viewed slide 2S and injects a newslide y27. if additional viewing is desired, a momentarydepression of switch 2t) causes the timer to reset to zero. A full viewing :interval -will transpire before the solenoid 22.is. again energized bythe timer. -Theswitch 16 is not reset when the timer motor is deenergized because the switch 16 must be driven against the xed stop 18 in order to be reset. Otherwise, a pulse would occur when switch is again closed and the slide would be ejected.

One novel feature of the interrupter is lack of a cam. The time setting is made from the front with the twist of a knob 8. Attached to the dial shaft 26 is the movable stop 12 whose angular displacement determines the time setting. Since timing is at a uniform rate, the scale of time setting shown on dial 13 is linear throughout its entire range.

Another novel feature of the invention is the movable switch 16. Rather than move a cam into the switch 16 as is general practice, the switch 16 is moved between stops. This is accomplished by aiiixing the snap-action switch device 16 to the timer shaft 7 and rotating it between stops 12 and 18. The actuator 17 `is thereby moved between its two limiting positions 17', 17". As the switch 16 oscillates between stops 12 and 18 it controls the electric load 22 in the manner desired. During its timed rotation it energizes the timing motor y1 and may energize an external electric circuit NC. Connection between the moving switch and a terminal block (not shown) is madewith flexible leads.

Another novel feature of the invention is the constant or variable torque reset spring which permits the choice of a second timed portion of the cycle either proportional to the first or substantially constant.

I claim:

1. A repeat cycle timer, including a snap acting switch actuable into either a conducting condition or a nonconducting condition, a timing motor energized through said switch when said switch is in said conducting condition and adapted to move said switch over a path of finite, adjustable length, a first stop located in the path of said switch and adapted to actuate said switch and thereby cause it to change its condition from one stable condition to another stable condition, a second stop located in the path of said switch and adapted to also actuate said switch and thereby cause it to change its condition from said other condition to said one condition, one of said stops movable to lengthen or shorten said path, said timing motor adapted to move said switch over said path in one direction, a prestressed return spring adapted to move said switch over said path in a return direction, said return spring connected to the adjustable one of said stops and adapted to be increasingly prestressed when said path is lengthened and to reduce the prestress of said lspring when said path is shortened to thereby maintain the return time of said switch substantially constant.

2. yIn a repeat cycle timer, in combination, a resettable snap acting switch adapted -to be oscillated over an adjustable length path, stops defining each end of the path, the snap switch reset from a conducting condition to a non-conducting condition at one end of said path and from a non-conducting condition to a conducting condition at the other end of said path, a timer motor energized through said switch and adapted to drive said switch at a timed rate when said switch is conducting, a reset spring adapted to drive said switch in a reverse direction when said switch is non-conducting and said motor is deenergized, said reset spring changeable as to tension as the length of said reset path is adjusted and a load circuit also controlled andtimed by said switch.

3. A repetitive cycle timer having, in combination, a snap switch, said switch having an actuator projecting from two opposite sides of said switch, a shaft supporting said switch and adapted to rotate said switch through an arc, an adjustable abutment engaged by said switch actuator limiting rotation of said switch in one direction, a stop engaged by said switch actuator limiting rotation of said switch in the opposite direction, an electric circuit closed when said switch actuator engages said adjustable abutment, a synchronous motor energized through said circuit, a speed reducer and a unidirectional clutch between said motor and said shaft adapted to drive said shaft at a uniform rate of speed in one direction, a reset Ispring having one end atiixed to said shaft and another end aixed to said adjustable abutment and adapted to rotate said shaft in the reverse direction after said switch actuator engages said stop and opens said circuit, said switch alternately rotated by said motor and then by said reset spring into contact alternately with said stop and then with said adjustable abutment, this cycling-repeated until power is removed, the duration of the reset time remaining substantially constant for various settings of said adjustable abutment, and a load circuit connected through said switch and controlled thereby.

4. In a cycle timer as in claim 3, an external circuit energized through said switch during its entire reset interval.

5. In a cycle timer as in claim 3, an external circuit energized through said switch during its entire motor driven interval.

6. In a repeat cycle timer, a plurality of spaced apart frame members, a unidirectional motor and reduction gear box mounted external to one frame member, a drive pinion mounted between the frame members and rotated by said motor and gearing, a unidirectional clutch between said gearing and said pinion, a drive shaft journaled in one of said frame members, a gear aiiixed to said shaft and meshing with said pinion, a reset spring coiled about said shaft and having its internal end aiiixed to said shaft, a presettable rotatable bracket member frictionally journaled in one other of said frame members in axial alignment with said shaft and having one end adapted to hold the external end of said spring and upon rotation of said bracket member in one direction to stress said spring additionally, a second bracket member aiiixed to said shaft and having at least one flat surface, a reset type snap acting switch aifixed to said flat surface, said swtich adapted to be rotated by said shaft in a plane normal to the axis of said shaft, said switch having a two ended actuator, one end of said actuator movable against said presettable bracket and the other end of said actuator movable against a fixed stop, a fixed stop attached to one of said frame members, an electric circuit including a source of power and said switch and said motor and adapted in one condition of said switch to energize said motor to thereby rotate said shaft and said switch at a constant speed between said presettable bracket and said xcd stop, and in another condition of said switch to deenergize said motor and to permit said reset spring to rotate said switch between said fixed stop and said presettable bracket, the condition of said switch reversed when said actuator strikes said presettable bracket and again reversed when said actuator strikes saidv fixed stop, the time of travel between said fixed stop and said presettable bracket being Isubstantially constant for all settings of said presettable bracket, and a load circuit through said switch energized during the entire time said switch travels between said fixed stop and said presettable bracket.

7. A cycle timer providing successive time cycles each of which comprises an adjustable interval and a substantially xed reset interval, having in combination, a movable interval determining element, a xed stop for said interval determining element, an adjustable stop, electric motor driven means to move said element at a fixed speed from said adjustable stop to said fixed stop the time required determining the adjustable interval, means placing current on said motor when said element reaches said adjustable stop and taking off the current when said element reaches said fixed stop, a prestressed coil spring having one end attached to said element for returning said element from said fixed stop to said adjustable stop, means connected to the other end of said spring to increase the prestress as the movable stop is rotated to increase said adjustable interval to thereby increase the antenna G speed of 'return travel of said `element as'the distance biet'w'eenfthe stops is increased Vto Vthereby maintain the reset interval substantially constant.

VKSf-In a cycle timer Vas in claim 3, said adjustable abutment rotatable about said shaft to lengthen or shorten thepath traveled by said switch toithereby proportionally increase or decrease the duration of the portion of the Vcycle'titnedby said motor driving said switch.

"9. In a 'cycle timer as in claim Y3, a time cancelling 'circuit comprising a manually operable switch connected in circuit with said motor and'adapted when opened during the time :that said motor is energized to deenergize Vsaid motor and permit said reset spring to return said rst named switch to said adjustable abutment without Valteringthe conditionk'of said first named switch, said manually operable "switch when reclosed adapted to reenergize said motor to permit said motor to drive said Virst named "switch the full length of its path 'and thus time fa full interval,

10. A timer, including 1n combination, a resettable double throw snap acting swit'chfstructure having an actuator tor urging the electric switch therein into two diierent conditions, a support, a unidirectional synchronous motor mounted on` said support and Yhaving reduction gearing and a unidirectional clutch and an output pinion,

-a shaftjournaled to said support and having a driven 'gear in mesh with said pinion and providing a support for jsaid switch, a reset spring coiled about said shaft and having one end affixed to said shaft, a fixed stop attached `to said lsupport and having one portion in the path of said actuator on said switch when said switch is rotated by said motor, an adjustable stop frictionally attached to said support and having one portion Vmovable into the path of `said actuator on said switch, a secondportion of Y `Isaid adjustable stop adapted to retain the outer end of said reset spring and to wind said spring additionally as said adjustable bracket is moved to lengthenthe path of said switch and tol unwind said springras said adjustable bracket is moved to shorten the path of said switch, the reset time of said switch thereby maintained substantially constant regardless of length of path of said switch.

11. In a repeat cycle timer adapted to time a settable Y `intervaland a Vreset Vinte al substantially"proportional thereto, in combination, a reset Atype snap vaction switch adapted to Vbe oscillated over fan adjustable length path, stops defining each end of thepath, the length voffsaid path proportional to the duratiogngof the settableinterval, said snap switch reset [from a conductingto a non-conducting condition `at one end of the path `and from a nonconducting to a conducting condition at theother end of the path, a timer motor energized through said switch and connected to drive said switch at a timed rate from one to the other of said stops when said switch is conducting, a Areset spring initially stressed to drive said switch in avreverse direction when said switch isA nonconducting and said motor is deenergiged, said reset `spring prestress increased as said motor drives said y,switchover its,pathand a load circuit controlledand `timed by :said switch; j j

1 2. In a repeat Ycycle timer, in combination, 'a resetf table snap acting switch adapted to be oscillated over an adjustable length path, stopsl defining each end of the path, the snappswitch resetfrom arconducting condition to anon-conducting condition at one end of said path and from a non-conducting condition to a conducting con- ,dition at the other end of said path, atimerjniotorrenergized through said switchand adapted to drive said switch along said path atta timed Yrate when saidswitch is conducting, a reset spring adapted to drive 'said switch in a reverse direction when said switch is non-conducting and said motor is deenergized, said reset spring adapted to be vadjusted as to tension as the length of said reset path is adjusted, and a load circuit also controlled land timed by Vsaid switch.

Y l References Cited in the dile-of this patent' UNTED STATES PATENTS Brown May 5, 1959

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