US3246090A - Stepping timer with normal and rapid advance speed control - Google Patents

Description

Aprifi" 12, 1966 F. R. BECK 3,246,090

STEPPING TIMER WITH NORMAL AND RAPID ADVANCE SPEED CONTROL Filed Feb. 6, 1963 4 Sheets-Sheet l T'imme GEAR mam-52.

sve ma G m TRAN INVENTOR. FReoEmcK R. BecK ATTORNEY 3,246,090 NG TIMER WITH NORMAL AND RAPID ADVANCE SPEED CONTROL F. R. BECK April 12,

- STEMI 4 Sheets-Sheet 2 Filed Feb. 6, 1.963

I INVENTOR. ZF EDE AQK R. B K

April 12, 1966 F. c 3,246,090

STEPPING TIMER WITH NORMAL AND RAPID ADVANCE SPEED CONTROL Filed Feb. 6, 1963 4 Sheets-Sheet 3 INVENTOR. FREDERICK R. BecK ATTORNEY April 12, 1966 F. R. BECK 3,246,090

STEPPING TIMER WITH NORMAL AND RAPID ADVANCE SPEED CONTROL Filed Feb. 6, 1963 4 Sheets-Sheet 4 INVENTOR. FReuemc R. Beam 3% i /9 My lz/ ATTORNEY United States Patent 3,246,090 STEPPING TIMER WITH NORMAL AND RAPID ADVANCE SPEED CONTROL Frederick R. Beck, Glen Ellyn, Ill., assignor to Controls Company of America, Melrose Park, 111., a corporation of Delaware Filed Feb. 6, 1963, Ser. No. 256,608 12 Claims. (Cl. 20036) This invention relates to timers of the type having provision for a normal timing speed and a rapid advance speed which is used for initially positioning the timer to the desired starting point or may be used to skip a portion of a program. The present invention is particularly related to the provision of a switching arrangement for de-energizing the circuits controlled by the timer during the time the rapid advance mechanism is operative.

Timers of this general class are referred to as power timers (since the timer is power driven to the desired starting point or to skip a portion of a program) and the initial design of this type employed two motors, one for driving the timer at a normal timing speed and a second motor which was employed for the rapid advance. In many instances it has been found desirable to de-energize the circuits controlled by the timer during the rapid advance of the timer and with this original design employing two motors this was handled rather neatly by having the rapid advance motor take the form of a shaded pole motor in which the armature was biased out of the motor frame so that when the motor was energized the magnetic force would pull the armature in and this axial motion of the armature was used to actuate the switch de-energizing the timer circuits. A second type of power timer uses only one motor which takes the form of a shaded pole motor having its armature biased from the center of the frame and movable into the frame to obtain the axial motion when the motor is fully energized. The motor in this design is fully energized only when the rapid advance mechanism is operative and at other times a voltage dropping resistor is put into series with the motor coil to reduce the flux density of the motor to a point where the biasing spring can move the rotor out of the frame. Under the latter condition the rotational speed of the motor is substantially the same as its speed when fully energized. Partial energization is used to drive what might be termed a timer timing arrangement which determines when the motor is to be fully energized to advance the timer to the next interval. The full energization of the motor is employer for the advancing motion to index the main timer one step and is also used when rapid advancing the timer to a desired starting point or when rapid advancing the timer to omit a portion of the available program. While the motor armature moves axially when fully energized it will be appreciated that this axial motion cannot be used to actuate a line switch as in the earlier power timer design since this would result in the line switch being actuated even when the timer was only to take on step. This would result in dropping out the machine circuits on each step. Since the initial action of the motor during rapid advance cannot be used to actuate a line switch the provision of a line switch for such a timer is a more complicated problem and it is to this problem that the present invention is addressed.

The principal object of this invention is to provide a line switch arrangement for power timers of the type having but one motor.

The single motor power timers heretofore proposed have all employed an axially shiftable armature in the motor for clutching in and out the stepping or (rapid) advance mechanism. The resultant necessity for bearings 3,246,090 Patented Apr. 12, 1966 capable of withstanding rotational and axial motion leads to undesirable considerations regarding motor life and performance and this invention is also directed to the provision of an improved design eliminating the need for axial movement of the rotor to thereby make possible a superior motor performance. The improved motor design results in better magnetic coupling to the armature which, in turn, gives better torque characteristics and insures better performance of the timer interval timing arrangement.

Still another object of this invention is to provide in conjunction with either the axially movable rotor arrangement or with the motor having the rotor fixed against axial movement a line switch controlling mechanism which is operative to actuate the line switch only in the event the mechanism calls for two steps (or more) in rapid sequence.

A. further object is to provide a line switch arrangement for single motor power timers, which switch will not be actuated on the initiated energization (or on the first step) of the motor and which will be returned to its normal position at the conclusion of the rapid advance.

A still further object is to provide a single motor power timer in which provision is made for positively returning the timer timing arrangement to an initial position from which it will start upon resumption of the normal timing operation of the timer.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the two embodiments shown in the drawings, in which:

FIG. I is a simplified showing of a timer embodying a movable rotor in the motor and provided with a line switch; 7

FIG. 2 is a fragmentary sectional view taken to illustrate the manner in which the cam arrangement prevents actuation of the line switch on the first step while pro viding for actuation of this switch on the second and subsequent steps in rapid sequence;

FIG. 3 is similar to FIG. 2 but shows a subsequent step in operation;

FIGS. 2A and 3A are perspective views corresponding to FIGS. 2 and 3;

FIG. 4 shows the switch operating mechanism in the position occupied when the switch has been actuated during rapid advance;

FIG. 5 is a view taken as indicated by meandering line 55 on FIG. 1 to show the mechanism provided for driving the line switch back to its normal position .upon resumption of interval timing;

FIG. 6 is a view from the left of the face splines provided for the clutching arrangement between the timing hub and the time base wiper carrier;

FIG. 7 is a view showing the three teeth on the face of the time base wiper carrier for engagement with the face splines and in which the teeth are unequally spaced to result in a minimal angular travel between the parts before picking up the drive;

FIG. 8 is a schematic wiring diagram of the pertinent parts of the timer;

FIG. 9 is a fragmentary view comparable to FIG. 1 but showing a modified arrangement in which the motor armature is not axially movable;

FIG. 10 is a fragmentary view showing the initial position of the parts of FIG. 9 prior to actuation of of the line switch; and

FIG. 11 is a view comparable to FIG. 10 but showing the parts in the position they occupy when the switch has been actuated.

It will be understood that the drawings of the present control do not represent a production control and the parts have been opened up to make the construction more understandable. The program timer includes a ca m drum having a plurality of disc cams 12, each of which is adapted to operate one or more switches engaging the periphery of the individual disc. This drum is adapted to be moved in steps and for ease of control this is usually taken to be about six degree steps. The timing can, however, be effected from a face cam or the like without departing from the scope of the present invention. The cam arbor is provided with a drive gear 14 which is engaged by pinion 16. Pinion 16 is carried on shaft 18 which carries gear 24 which is the end of a stepping gear train including gears 21, 22, 23, 24, 25, 26, and 27. Gear 27 has a clutch half 28 fixed thereto while the other clutch half 30 is fixed on rotor shaft 32. The rotor 34 of the shaded pole motor 35 is normally biased to the right (as illustrated) so that it is only partly in the motor frame 36. The rotor is biased by spring 38 which is compressed between member 40 and counterweight 42 which bears on rocker 14 pivoted at 46 with the other end of the rocker bearing against the end of rotor shaft 32. When the shaded p-ole motor is only partly energized there is insufficient magnetic flux in frame 36 to pull rotor 34 into the frame. Therefore, the rotor will rotate at its normal speed but in the position shown in FIG. 1. Under these circumstances it will be obvious that the stepping gear train is not driven and, hence, the timing drum 10 is not rotated.

Rotation of the shaded pole motor armature 34 in the position shown in FIG. 1 will serve to rotate shaft 32 in its bearing 48 and turn pinion 50 to drive a timing gear train 52 which includes gears 53, 54, 55, 56, 57, 58, 59, 6t 61, 62, and 63. This gear train is driven whenever the shaded pole motor is energized, whether the motor is only partly energized or is fully energized. The counterweight 42 acting on the rocker 44 serves to counterbalance the weight of rotor 34 to prevent axial motion of the rotor by reason of vibration of the machine in which the timer is mounted. Gear 63 is rotatably retained on the fixed stub 64 by the vD-ring 66 and carries an annular member 6 8 provided with face splines (FIG. 6) which are adapted to be engaged by one of the three spaced teeth 70 carried on the cylindrical portion 72 of the time base wiper carrier assembly 74. The three teeth are not equally spaced so that a minimal angular displacement between the parts 68 and 72 will be required to engage one of the teeth with a face spline. The reason for this will be pointed out more fully hereinafter.

The cylindrical portion 72 is a part of the wiper carrier 74 having the central hub 76 rotatably and slidably mounted on the sleeve bearing 78 projecting from stub 64. The left end of the sleeve bearing 78 carries a D- ring 80 against which spring 82 seats to bias the carrier 74 to the right as viewed in 'FIG. 1 and this, in turn, urges the teeth 70 on portion 72 into engagement with the face splines on ring 68 so while the timing gear train 52 is running it will normally drive from gear 63 into ring 68 and turn carrier 74. The carrier 74 has a hub 84 on which the ring portion 86 of wiper 88 is slidably mounted. The wiper includes radial arms and wipers 90, 90 which project axially into contact with a printed circuit on the face 92 of insulated circuit board 94. Spring 96 acts to urge the wiper assembly into contact with the printed circuit. It will be appreciated that if the carrier 74 is moved to the left the spring 96 will yield so as to not damage wipers 90, 90. The wipers are driven by the channel-like projections 93 and 111i) projecting fro-m carrier 74. It will be noted the channellike member 100 is somewhat longer than 98 so that it may engage the zero position stop member 162 as illustrated in FIG. 1.

As the carrier assembly 74 is driven from the zero position illustrated in FIG. 1 the clock spring 164, which 4- has one end fixed to stub 64 and the other end faxed to cylinder 72, is wound up in a direction tending to drive the carrier assembly back to stop 102. If the carrier assembly is moved to the left to disengage the clutch comprised of ring 68 and teeth the clock spring will drive the carrier assembly back to its zero position. This action is employed whenever the rapid advance is operative so that the wipers 90, will always start from a zero position. The timing wipers are used to bridge printed circuit elements at preselectable intervals starting from the zero position to determine when the rapid advance or stepping gear train will become effective. Additional details of this timing function will be described hereinafter with respect to the circuit diagram.

In the preceding description reference was made to movement of the carrier to the left against the bias of spring 82. This movement is brought about by movement of pin 106, slidable in stub 64, to the left. The pin is moved to the left by face cam 1% carried on shaft upon which gears 23 and 24 in the stepping gear train are mounted. The face cam 10% is so related with respect to the wipers 112, 112 on the left end of shaft 110 that the wipers will have entered into a bridging relationship on the holding tracks of the printed circuit so as to insure electrical continuity to the shaded pole motor to continue full energization thereof until a complete step has been taken. After the bridging condition has been reached the pin 106 can be moved to the left to release the carrier assembly 74 for return to its zero position under the drive of the clock spring 104. At the zero position of the stepping gear train and at the completion of the step on the cam drum 10 a drop portion of face earn 168 will be reached allowing pin 106 to return to the right and permit re-engagement of the wiper carrier assembly 74 with the timing gear train.

The timing wipers 9t), 99 wipe across a printed circuit arranged on board 94 in a circular path. FIG. 8 shows this printed circuit along with the printed circuit contacted by the main timing cam wipers 114 which in FIG. 1 number four while in FIG. 8 they are shown as three wipers 114a, b, and c. When laying out the printed circuit arrangement as in FIG. 8 it is possible to illustrate the circuit with only three wipers whereas in laying out the actual physical arrangement of the printed circuit on board 94 it is expedient to use four wipers. It will be understood, however, the principle remains the same. Referring now to FIG. 8 it will be noted that the shaded pole motor 35 is across the lines L1 and L2 by a circuit going from L-1 through the shaded pole motor into contact strip 116 and from contact strip 116 through a printed lead 118 which in the interval (as distinct from rapid advance or stepping) is connected to the dropping resistor 129, to printed circuit track 122 and from there through line switch No. 2 which connects to lead 124 which goes through the main timer bank to come back through lead 126, through the N0. 1, line switch to line L-Z. After any given step the dropping resistor is in series with the shaded pole motor and the wiper assembly 90, 90 is at the zero point at the right-hand end of the circuit strip 122. Now, as the interval progresses the wipers 90 move to the left (actually in a circular path) along the strip to Contact first the various spray contacts 123, which can be employed to give a spray rinse, but the important consideration is that these wipers will also bridge contacts 130, 132 and 134 and, depending upon the printed circuit arrangement bridged by the main wiper assembly 114, one of these will be electrically hot so that when the wiper assembly 96 bridges between strip 122 and pad 13%, 132 or 134, the dropping resistor 120 will be shunted and full line voltage will be applied to the shaded pole motor to permit the motor to pull in the rotor and drive the stepping gear train. The pads 13%, 132 and 134 correspond respectively to intervals of two, four and six minutes so that in any given position of the timer there is available, by the arrangement of the printed circuit, a possible interval of two minutes, four minutes or six minutes and this greatly enhances the versatility of this type of timer. The two minute pad 130 is connected to the main printed circuit pattern 136 while the four minute pad is connected to the pattern 138. The patterns 136 and 138 will be energized whenever the main wiper assembly 114 bridges between 116 and either 136 or 138. The main wiper assembly, in effect, moves from top to bottom (on this pattern in FIG. 8) and the particular pad contacted by the wiper assembly 114 can be visualized by imagining a straight line across the various patterns. When the main wiper 114 does not contact either pattern 136 or 138 then a full interval of six minutes will be achieved since the pad 134 is connected directly to the hot strip 116 and when the timing wiper 90 gets out to the full left position the resistor 120 will then be shunted.

It will be noted that the hot strip 116 on the main printed circuit is also connected to a strip 140 which is adapted to be contacted by the stepping wiper assembly 112. The stepping wiper assembly normally will occupy a position at the right of strip 140 resulting in .an impossibility of completing a circuit bridging from 140 through the wiper 112 to the strip 142. However, when the stepping drive becomes operative and starts driving the main cam 10 it will also start driving the stepping wiper 112 which results in the wiper bridging strips 140 and 142 to establish a holding circuit shunting resistance 120 until the stepping wiper gets back to its initial position in which it cannot bridge these two strips. At this time any shunting occurring through the wiper assembly 112 is interrupted and the system must look for another electrical path shunting resistance 120 and, failing to find such a path, the resistance 120 is placed back in the circuit and the stepping gear train is taken out of action.

Now considering FIG. 8 in conjunction with FIG. 1 it will be remembered that when the motor is operating at a reduced voltage the time base wiper 90 is searching along contact strip 122 until it finds a hot pad 130, 132 or 134. When the wiper contacts such a hot pad the dropping resistor is shunted and the motor goes into a full speed drive advancing the main cam. As soon as this occurs the step wiper 112 moves into position to maintain the shunt circuit around resistor 120 and in the meantime the time base wiper assembly is disengaged from the timing gear train 52 and returned to its zero position so that it will be at the zero position ready to resume an accurate timing of the next interval if called upon so to do. Without at this point going into the manner in which multiple steps are taken, sufiice it to say that the face cam 108 will operate to disengage the time base Wiper assembly for return to zero on each step so that if a number of steps are to be taken in rapid sequence the timer base wiper assembly will not be building up time but will always be starting from a zero position.

The present printed circuit arrangement incorporates a power drive arrangement for seeking out a desired starting point upon actuation of any of the push button switches A, B, C, D, E, F, G, or H which are of the latching variety, that is, if one of these buttons is depressed it will release the previously depressed button for return to its normal position. The momentary switch 144 is actuated whenever any of these buttons is depressed.

T he switch labeled ABO means all buttons out and if all buttons somehow are in the released position then there will be an open switch ABC to prevent the continuous seeking by the shaded pole motor. The circuit arrangement here is such that the seeking system will seek an open circuit and, of course, if all buttons are out and the ABO switch is open then the seeking circuit will find pad 146 on the printed circuit arrangement. It will be noted that each of the push buttons is connected to one or more small circuit pads arranged at various positions along the path of the pattern 148 for contact by wiper 1140. In each position of the wiper assembly 114 the wiper 1140 will contact either pattern 148 or one of the small pads corresponding to one of the push buttons. Let us suppose, for the moment, that push button I is depressed with the wiper assembly starting in the position shown in FIG. 8. When the button I is depressed the momentary switch 144 will be closed to place the shaded pole motor directly across the lines L-1, L-2. The normally open contacts of the No. 1 line switch will now prevent completion of a circuit from contact strip 116 through wiper 114 and into the strip 148 and the various small pads. By a mechanism to be described hereinafter this line switch will be closed when the stepping drive takes a second step and, therefore, the push button I must be held down long enough for the stepping drive to enter the second step. This is but a fraction of a second. Upon closure of the line switch contact to complete a circuit from bus 150 through lead 152 and 154 through L-2 it will be apparent that the shaded pole motor will remain directly across the line by reason of the circuit through the bridging wiper 114 and strip 148 and the various pads which are connected to bus 150 through the normally closed selection switches. Therefore, the motor will continue driving the main cam drum at high speed until the pad corresponding to the now open bush button I is reached and thereupon the circuit shunting the shaded pole motor is broken. This results then in the dropping resistor 120 being placed in series with the shaded pole motor and the timing of an interval will commence.

In the preceding paragraph it was mentioned that the No. 1 line switch will not be actuated on the first step taken by the mechanism and the reason for this is that when this mechanism takes a step it has no way of knowing whether only one step is required or more steps are required and, therefore, any actuation of the line switch should not occur each time the initial step is taken but, rather, it is better to wait until the second step. If the second step is taken this is generally indicative that more steps will be taken and the line switch shouldnow be actuated to take off the circuits controlled by the timer so as to save wear and tear on the machine as well as reduce noise and switching problems associated with high starting loads and the like.

FIGS. 1 through 4 illustrate the manner in which the line switch is operated in this embodiment. The two line switches are stacked and mounted as illustrated and are provided with a common actuating pad 156 which is adapted to be actuated by lever 158 mounted on bracket 160 for pivotal and rocking motion, that is, it can both pivot and rock sideways. The lower end of this lever in the normal timing position rides on the cylindrical hub portion 162 of the gear assembiy 23, 24. The lower end of the lever 158 is biased to the right by its spring 164 but is restrained from moving to the right by the arm 166 projecting behind or to the right of the lever in FIG. 1. This arm 166 is carried by lever 163 pivoted at 171) and having its left-hand end riding on the periphery of carrier 74. The periphery of carrier 74 is notched, as illustrated in FIG. 5, so that in the zero position of the time base wiper assembly the end of lever 168 can fall into the notch 172 to allow the spring 164 to rock lever 158 counterclockwise if the lever is free so to do.

In FIG. 2 the lower end of lever 158 is shown resting against the cylindrical portion 162. It will now be remembered that rotation of gears 23, 24 and of the face cam 108 will actuate pin 106 to declutch the time base wiper assembly for return to zero but this requires some degree of rotation of the gears 23, 24. Immediately below, or to the right of, the cylindrical portion 162 there is a cut-out portion or shelf 174 bounded by a rising cam surface 176 and a holding cam surface 178. In the amount of rotation required to deciutch the time base wiper assembly for return to zero the face 180 will have rotated at least in part under the lever 158 to prevent movement of lever 158 by spring 164 until the shelf 174 again underlies the lever more or less in the same position as illustrated in FIG. 2. it will be recalled that at the time the gears 23, 24 have rotated sufficiently to declutch the time base wiper assembly and permit return of the wiper assembly to its initial or zero position this shelf 180 will prevent movement of the lever 15% except to bring the lever into firm contact with face 131?. The lever is permitted to move in this direction at this time because the left-hand end of lever 163 has fallen into notch 172 on the perimeter of carrier '74. Now, then, if still another step is to be taken, the hub assembly of gears 23, 24 will continue rotation and now the rising surface 176 will cam lever 158 to the position shown in FIG. 3 where it now is free to move under influence of spring 164 to the cylindrical surface 182. As it is carnmed out it will be appreciated line switches 1 and 2 are actuated as illustrated in FIG. 3. FIG. 4 illustrates the position of lever 158 when it has fallen onto shelf 174 prior to being actuated by the rising surface 17%. From this description it will be apparent that the line switch actuating lever 158 cannot actuate the switches until the stepping gear train is into the second step.

When the timer reaches the desired position it is now necessary to return the line switches to their normal position. The natural spring bias of switches l and 2 will tend to rock the upper end of lever 1553 to the right as viewed in FIGS. 2 and 3. However, it cannot move to the right until it gets back to the small cylindrical diameter 162 and this is accomplished by the start of the timing function by reason of gear train 52 being reconnected to the time base wiper assembly and rotating carrier 74 so the rising surface 184 will cam lever 168 back to its normal position and cause arm 162 to pull lever 153 back to a position overlying the small diameter 162 whereupon the bias of switches l and 2 will move the lower end of the lever against this surface.

Now, turning to the embodiment shown in FIGS. 9, l0, and 11, this arrangement has an advantage in several respects. It will be recalled that in the first embodiment it was necessary to use the time base wiper carrier to drive the line switches back to their normal positions whereas this embodiment will return immediately upon the shaded pole motor being operated at reduced voltage. This present embodiment also has an advantage in that it avoids axial motion of the rotor which results in far superior bearing performance and motor design. Now, referring to these figures in detail, it will be noted that here the shaded pole motor 2% has the rotor 292 mounted slightly out of the frame 294- so as to permit the movable clutch assembly 206 to pull in close to the frame when the frame is fully magnetized by operation of the motor at full line voltage. In other words, in this assembly the magnetic field set up by full energization of the motor is used not to pull the rotor but to pull the clutch assembly 206. This clutch assembly is merely slidable on the motor shaft 2% and is provided with spaced collars 213 between which the forked ends of lever 212 project to pick up the motion so that as the clutch 2% moves to the right when the motor is fully energized the lever 212 will rock about its pivot 214 and move the assembly from the full line position in FIG. 9 to the dotted line position in FIG. 9. It will be noted that the pivot 214 is carried by a bracket assembly 216 which also carries a biasing spring 218 which serves to bias the lever and also clutch 206 to a position in which the clutch is disengaged. The assembly also carries another spring 220 which is relatively weak and serves only to cause the switch actuating arm and follower 222 to tend to follow the motion of lever 212. It is important to remember that spring 218 is stronger than spring 220 so that its influence controls operation of the clutch. The switch actuating arm and follower 222 is normally in the timing position (in the position shown in full lines) and in this position it is riding on the small cylindrical diameter 224 of the stepping gear train gear hub carrying gears 23, 2 as in the first embodiment. When the motor is fully energized the clutch 206 pulls to the right and tends to throw arm 222 to the left. However, before the lever can move down to the flat face 226 the gear hub must make a rotation pulling the face 228 out from under the arm 222. In other words, at the start of the clutching action the surface 223 underlies the arm and prevents pulling the arm to the left in FIG. 9. When, however, the surface 226 generally underlies the arm the arm can now move under influence of the light spring 229 against the surface 226 where the cam configuration 230 will act to cam the arm (FIG. 10) to the left to actuate the snap line switch 232. After the surface 230 has moved the arm to its maximum left position the influence of the light spring 221) will now pull the arm 222 further to the right to ride on the large diameter portion 234 of the hub assembly. When the motor is now dropped back to a reduced voltage the stronger spring 218 will disengage the clutch 2196 and at the same time will throw lever 222 back to its normal solid line position in FIG. 9 which will also permit the normal bias of the snap switch 232 to return the arm to the small diameter hub 224 whereupon the switch is returned to its normal position. Thus, the action of the clutch spring is used to restore the line switch immediately rather than having to wait and drive it back to its normal position. This is a desirable situation and obviates the necessity for using a power drive off the time base wiper carrier 74- to drive the line switch back to normal. The available torque when operating at reduced voltage is not great and it is desirable to avoid the necessity for using some of this torque to drive the switches. By reason of the fact that the switch assembly can now be a snap switch it is also possible to rewire the circuit to use only one line switch instead of the two shown in conjunction with FIG. 8.

t will also be appreciated that this assembly in addition to avoiding the requirement for axial rotor motion now avoids the need for the counterweight used in conjunction with the first embodiment.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without depart ing from the spirit of the invention or from the scope of the appended claims.

I claim:

1. A timer comprising, a programming device adapted to be advanced in a step-by-step manner to control circuits determining a sequence of operations, an interval timer for timing the period of time between step advances of the device, a motor driving the interval timer, stepping drive means including a clutch connecting the motor to the program device, means operated by the drive means returning the interval timer to a starting position each time the interval timer advances a step, switch means, means operated by the drive means and actuating the switch means only after the drive means has been continuously operated by the motor to drive the program device more than one step.

2. A timer including a motor, a switch actuating program device to be actuated by the motor in finite steps, drive means connecting the motor to the program device, a switch, means operatively associated with the drive means for actuating the switch and including means pre venting actuation of the switch until the drive means has operated continuously to drive the program device in excess of one step.

3. A timer comprising, a program device including switches controlling circuits in a program sequence and adapted for step-by-step advance over a prescribed path in finite increments either in rapid sequence to skip some of the program or with an interval of time between steps, drive means connected to the program device, an interval timer regulating operation of the program device drive means and serving to determine the duration of the interval between steps of the program device, means connected to the program device drive means and determining when the drive means should advance the program device in rapid sequence, a rapid advance switch operable to de-energize at least some of the circuits controlled by switches of the program device, means controlled by the drive means and operating the rapid advance switch and including means controlled by the drive means and to delay rapid advance switch operation during the first step of any advance, and means operated by the internal timer and restoring the operation of the interval timer whereby the operating means cannot operate the rapid advance switch except after at least one step of any ad- Vance.

4. A timer according to claim 3 including means phasing operation of the interval timer with the program device so the interval timer is positioned to start timing an interval upon conclusion of any advance of the program device.

5. A timer according to claim 4 in which the phasing means includes means operated by the program device drive means and acting on the interval timer to restore the interval timer to its initial position each time the program device is advanced a step.

6. A timer comprising, a program device including circuit control means and adapted for step-by-step advancement in finite increments either in rapid sequence or at timed intervals, drive means driving the program device, switch means operative to de-energize the circuit control means, actuating means operating the switch means, first cam means operable with the drive means to actuate the actuating means, means holding the actuating means from the cam means and responsive to operation of the drive means to release the actuating means, second cam means preventing the actuating means from following the first cam means until the drive means has continuously driven the program device more than one step.

7. A timer according to claim 6 including means operative upon completion of operation of the drive means to restore the switch means to its normal inoperative position.

8. A timer according to claim 7 in which the last named means is directly responsive to the operational state of the drive means.

9. A timer according to claim 6 in which the first and second cam means are carried on a common rotating part of the program device drive means with the first cam means moving the actuating means radially and the second cam means controlling axial movement of the actuating means towards the first cam means.

10. A timer comprising, program device adapted for step-by-step advance over a prescribed path in finite increments, an electric motor having a fixed stator and an axially fixed rotor, means connected to the rotor and timing the intervals between steps of the program device, said motor operating at reduced voltage or full voltage, drive means for the program device including a clutch interposed between the motor and the program device, said clutch including a drive element rotating with said rotor and a driven ferromagnetic element magnetically coupled to said stator, and attracted by the magnetic force in said stator, when the motor is operated at full voltage to engage with and be driven by the drive element, and means biasing the driven clutch element away from the stator with a force suflicient to overcome the magnetic force in the stator when the motor is operated at reduced voltage.

11. A timer according to claim 10 including a switch, and means responsive to the operational state of the clutch to operate the switch.

12. A timer according to claim 11 in which the last named means includes means delaying actuation of the switch after engagement of the clutch until the clutch has been continuously energized in excess of one step of the program device.

References Cited by the Examiner UNITED STATES PATENTS 2,730,671 1/1956 Van Ryan 310-78 X 2,905,239 9/1959 Dietz 20037 X 2,963,628 12/1960 Ostland 200-38 3,109,073 10/ 1963 Lewis et al. 20038 3,109,074 10/1963 Lewis et al. 20038 3,123,683 3/1964 Lewis et al ZOO-38 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

H. M. FLECK, Assistant Examiner.

Claims (1)

1. A TIMER COMPRISING, A PROGRAMMING DEVICE ADAPTED TO BE ADVANCED IN A STEP-BY-STEP MANNER TO CONTROL CIRCUITS DETERMINING A SEQUENCE OF OPERATIONS, AN INTERVAL TIMER FOR TIMING THE PERIOD OF TIME BETWEEN STEP ADVANCES OF THE DEVICE, A MOTOR DRIVING THE INTERVAL TIMER, STEPPING DRIVE MEANS INCLUDING A CLUTCH CONNECTING THE MOTOR TO THE PROGRAM DEVICE, MEANS OPERATED BY THE DRIVE MEANS RETURNING THE INTERVAL TIMER TO A STARTING POSITION EACH TIME THE INTERVAL TIMER ADVANCES A STEP,

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