US3712966A

US3712966A - Interval timing mechanism with improved cam follower for cam operated timers

Info

Publication number: US3712966A
Application number: US00173006A
Authority: US
Inventors: N Watts; W Josam
Original assignee: Westinghouse Electric Corp
Current assignee: KING-SEELEY Inc; KING-SEELEY Inc A CORP OF DELAWARE; ABB Inc USA
Priority date: 1971-08-19
Filing date: 1971-08-19
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23
Also published as: CA926898A

Abstract

A TIMING DEVICE INCLUDING A SWITCH FOR AUTOMATICALLY CONTROLLING THE ENERGIZING TIME OF AN APPLIANCE. THE TIMING DEVICE INCLUDES A ROTOR DISC HAVING A FACE WHICH DEFINES PREDETERMINED CAN PROFILES, AND A ROCKING LEVER WHICH COOPERATES WITH THE CAM PROFILES TO ACTUATE THE SWITCH. THE ROCKING LEVER INCLUDES TWO INTERGAL CAM FOLLOWERS, WITH ONE OF THE CAM FOLLOWERS BEING CONSTRUCTED TO RETURN AN ASSOCIATED TIMIMG INDICATOR TO ZERO AT THE TERMINATION OF THE ENERGIZING TIME.

Description

Jan. 23, 1973 N. B. WATTS ETAL 3,712,966

INTERVAL TIMING MECHANISM WITH IMPROVED CAM FOLLOWER CAM OPERATED TIMERS S Sheets-Sneet 1 Filed Aug. 19, 1971 INVENTORS Norbert B. watts and Walter P. Josom ATTORNEY Jill. 23, 1973 B, -r5 EFAL 3,712,966

INTERVAL TIMING MECHANISM WITH IMPROVED CAM FOLLOWER CAM OPERATED TIMERS Filed Aug. 19, 1971 5 sheets sneet 2 FIG.5.

FIG3

Jill. 23, 1973 5 EI'AL 3,712,966

N. B; WAT I RVAL TIMING MECHANISM WITH IMP ED AM FOLLOWER CAM OPERATED TIME Filed Aug. 19, 1971 5 Sheets-Sneet 3 IS'I/ FIG.6.

FIG]

United States Patent 3,712,966 INTERVAL TIMING MECHANISM WITH IMPROVED CAM FOLLOWER FOR CAM OPERATED TIMERS Norbert B. Watts and Walter P. Josarn, Raleigh, N .C.,

assignors to Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed Aug. 19, 1971, Ser. No. 173,006 Int. Cl. H01h 43/10 US. Cl. 200-38 R 7 Claims ABSTRACT OF THE DISCLOSURE A timing device including a switch for automatically controlling the energizing time of an appliance. The timing device includes a rotor disc having a face which defines predetermined cam profiles, and a rocking lever which cooperates with the cam profiles to actuate the switch. The rocking lever includes two integral cam followers, with one of the cam followers being constructed to return an associated timing indicator to zero at the termination of the energizing time.

BACKGROUND OF THE INVENTION Field of the invention The invention relates in general to interval timers, and more specifically to interval timers suitable for controlling the operating time of cooking ranges.

Description of the prior art Certain appliances, such as electric and gas ranges, often include means for automatically controlling the stopping time thereof, i.e., the time at which the appliance is deenergized. Still others include means for automatically delaying the energization of the appliance for a preselected period of time, at the end of which the preselected energization time commences. The controls for providing these automatic features should be uncomplicated, both from a manufacturing viewpoint, and from the users viewpoint, and they should be operable with a relatively low turning torque on the operating shaft.

In the prior art, it is common to control the energization time of an appliance by a control shaft which has a first axial position during a timing interval, and a second axial position at the end of the timing interval, with the axial movement of the shaft between the two positions being used to actuate an associated switch. The shaft is first pushed axially inwardly by the operator, to establish the first axial position thereof, and the shaft is then manually rotated to select the interval to be timed. When the timing interval is terminated, the shaft automatically snaps to the second axial position.

Co-pending application Ser. No. 120,538, filed Mar. 3, 1971, which is assigned to the same assignee as the present application discloses a stop shaft arrangement which only requires rotary motion on the part of the operator to set the energization time, thus simplifying the operating procedure. In this arrangement, a rotor disc is fixed to a stop or control shaft, with the rotor disc having a predetermined cam profile on one face thereof. The cam follower assembly is biased to this face, and it co-acts with a lever disposed to control the electrical condition of a control switch.

This new and improved stop shaft arrangement has many advantages over the push and rotate type stop shaft, and it would be desirable to further improve its operation and construction, such as (a) by reducing the turning torque required to selected the energizing time,

3,712,966 Patented Jan. 23, I973 SUMMARY OF THE INVENTION Briefly, the present invention is a new and improved interval timer having a clock shaft and a stop shaft, with the latter actuating a switch to automatically control the energization time of the associaed appliance, when it is desired to place the operation of the appliance under automatic control. The stop shaft requires only rotary motion to effect its operation, i.e., the shaft is rotated until an associated pointer selects the desired interval to be timed. The rotary motion of the stop shaft, when manually set, and under the influence of the motive means, such as a synchronous motor and associated gear train, is transformed into mechanical motion which has a direction substantially parallel with the axis of the stop shaft, by providing a predetermined cam surface on one face of a rotor disc fixed to the stop shaft. A pivotal or rocking type lever is provided for actuating the control switch, with the rocking lever having first and second spaced cam follower members formed integrally therewith. The cam followers are biased to the face of the rotor disc, transforming rotary motion of the rotor disc to pivotal movement of the rocking lever, which movement actuates the control switch. This construction reduces frictional losses to a minimum, thus reducing the torque required to actuate the stop shaft. At least one of the cam followers has one end shaped to advance the rotation of the stop shaft by a predetermined angle as the cam follower drops into a depression in the cam profile at the end of the selected timing interval, to return the associated pointer to zero with a positive action.

The start of the timing interval may be delayed for a predetermined period of time, if desired, by adding a start shaft connected to a gear assembly in the motive means, which delays the application of the motive means to the rotor disc by a preselected interval of time.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings, in which:

FIG. 1 is a view in side elevation of an interval timer embodying the teachings of the invention;

FIG. 2 is a fragmentary plan view, partially cut away, of the interval timer shown in FIG. 1;

FIGS. 3, 4 and 5 are side elevation, plan, and right end elevation views, respectively, of a rocking lever constructed according to the teachings of the invention which is utilized in the interval timer shown in FIG. 1;

FIG. 6 is a fragmentary elevational view, partially in section, illustrating the position of the rocking lever when a delayed start feature is utilized and set;

FIG. 7 is a view of the rocking lever, similar to that shown in FIG. 5, except with the delayed start not used, or terminated;

FIG. 8 is a fragmentary view of the rocking lever as it starts to drop into a depression in the cam profile at the end of the preselected timing interval;

FIG. 9 is a fragmentary view of the rocking lever after it is dropped into the cam depression; and

FIG. 10 is a fragmentary view of the rocking lever when the stop shaft function is not being used and the associated appliance is under manual control.

3 DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, and FIG. 1 in particular, there is shown, in side elevation, an interval timer constructed according to the teachings of the invention. Interval timer 10 includes a stator structure or frame 11 having two spaced

support plates

12 and 14, two spaced support members 88 and 90 which extend between the support plates and motive means 16 including a synchronous motor 18 and a clock time mechanism 20. This portion of the interval timer 10 may be of conventional construction, with a motive force being initiated by the gear 26 associated with the synchronous motor 18, which drives gearing for operating hour and minute hands 28 and 30 of a time clock, and a minute timer hand 32, all of which are disposed about a clock shaft 34. The clock time mechanism 20 is disclosed and described in detail in US. Pat. 3,564,310, which is assigned to the same assignee as the present application.

The clock time mechanism 20 provides motive force, such as from pinion gear 35 to a gear train 22, which, as set by the start and

stop shafts

36 and 38, respectively, perform the functions of actuating a switch 24 at preselected times.

Switch 24 is sectioned to clearly illustrate a pivtotable switch operator 37 which, in response to rocking lever 39, controls the electrical condition of switch 24. Rocking lever 39 is constructed according to the teachings of the invention, and will be described in detail hereinafter. Switch 24 includes a fixed contact 40 connected to terminal 42, and a resilient electrically conductive finger 44 connected to terminal 46. Finger 44 is biased such that a contact 48 at its free end engages the fixed contact 40. The switch operator 37, when pivoted upwardly in response to rocking lever 39, contacts the resilient finger 44 and moves its contact 48 away from the fixed contact 40. Switch 24 may include a similar contact arrangement on the portion thereof cut away, with the resilient finger of this additional contact arrangement being actuated by protuberance 50 on the switch operator. A similar protuberance on the switch operator 37 is also used to actuate the finger 44 associated with the first contact arrangement described.

Rocking lever 39 is pivotally mounted on frame 11, such as by providing two spaced projections on support plate 12, which establish a fulcrum 52. A substantially U-shaped spring member 55 biases end 57 of rocking lever 39 toward the support plate 12. The angular position of rocking lever 39 about its fulcrum 52, and thus the electrical condition of switch 24, is responsive to the setting and operation of gear train 22. Gear train 22, in the embodirnent of the invention shown in FIG. 1, includes both a delayed start feature, as controlled by start shaft 36 and gear assembly 54, and a controlled energized time feature, such as cooking hours if the appliance is an electrical or gas range. The latter feature is controlled by stop shaft 38 and rotor disc 56. Stop shaft 38 may extend through rotor disc 56, with the shaft 38 being rotatably supported by the spaced

support plates

12 and 14. More specifically, gear train 22 includes idler gears 60 and 62 which receive motive force from pinion 35 and transmit it to gear 64, which is the lower gear of the gear assembly 54. Gear assembly 54 also includes an upper gear 66. The lower gear is disposed about start shaft 36, but it is free to rotate relative thereto, in response to the constant rotation of idler gears 60 and 62. The upper gear 66 is fixed to the start shaft 36, and the start shaft 36 extends beyond gear 66, through the upper support plate 12, to form an operating rod portion 68 for end 59 of the rocking lever 39, as will be hereinafter explained.

Start shaft 36 is axially movable, with the gear 66 and start shaft 36 being biased axially downward as viewed in FIG. 1, by a spring 70 disposed about start shaft 36, between gear 66 and the upper support plate 12.

The lower gear 64 includes an upstanding nose 72 fixed to the uppermost face of the gear, and the upper gear 66 includes an aperture 74, best shown in FIG. 2, which is a fragmentary plan view of the gear train 22. The nose 72 and aperture 74 are disposed on like radii of their respective gears.

When it is desired to automatically control the energized time of the associated electrical appliance, and to delay the start of the energized time, shaft 36 is manually pressed inwardly to overcome the urging of spring 70, and the start shaft 36 is then rotated, in either circumferential direction, until pointer 76, which is secured to the shaft 36, points to the desired time delay interval. The depressing of the start shaft 36 frees the nose 72 from the aperture 74, allowing the shaft 36 and gear 66 to then be rotated to the desired time delay setting, in which the nose 72 rests against the inner face of gear 66 and holds the start shaft 36 and gear 66 in this depressed axial position. In this position, the actuating rod portion 68 of shaft 36 is fully extended, lifting end 59 of rocking lever 39 to its uppermost position, as well as the switch operator 37, to change the electrical condition of the associated switch contact. Movement of gear 66 to the depressed axial position of shaft 36 moves the gear 66 against a ratchet spring 78 which is fixed to support member 88. Ratchet spring 78 provides a slight resistance to turning torque applied to shaft 36, and thus provides the function of retaining the gear 66 and shaft 36 in the selected angular position while the delayed start interval is being timed out.

During the selected delayed start time interval, gear 64 of the gear assembly 54 is rotating, while gear 66 is held in the selected position by ratchet spring 78. Since gear 64 does not directly mesh with any gear further along in the gear train, the motive force provided by the clock mechanism 20 terminates at gear 64. When gear 64 rotates to the point where its nose 72. is in alignment with the aperture 74 in gear 66, signaling the end of the delayed start time interval, spring 74] snaps the gear 66 and start shaft 36 to a new or second axial position, retracting the actuating rod portion 68 of shaft 36, enabling switch 24 to change its electrical condition.

When the nose 72 enters the aperture 74 in gear 66, gears 64 and 66 are locked together, and gear 66 is no longer restrained by the ratchet spring 78. Thus, gears 64 and 66 rotate together under the influence of the motive force provided by the clock mechanism 20. FIG. 1 illustrates the gear assembly 54 set for a predetermined time delay, while FIG. 2 illustrates gear assembly 54 after the delay period has terminated.

Gear 66 has its teeth engaged with the teeth of an idler gear 80 in both of the axial positions of shaft 36. In the set or depressed position of gear 66 it imparts no rotation to the idler gear 80, since gear 66 does not rotate in this mode. Once gear 66 is locked to gear 64, however, idler gear 80 starts to rotate, providing motive force to the rotor disc 56, which is fixed to stop shaft 38.

Idler gear 80, as best illustrated in FIG. 2, is yieldably biased towards rotor disc 56, for purposes which will be hereinafter explained. Idler gear 80 includes a support shaft 82, with the support shaft 82 being slidably fixed to support plate 14 in an elongated opening 84 disposed in the support plate. A spring member 86, which has its ends fixed to vertical support members 88 and 90, urges the idler gear 80 towards the end of slot 84 which is adjacent to rotor disc 56. The upper portion of idler gear 80' may be slightly dished to eliminate the possibility of interference between the idler gear and the U-shaped spring member 55 which is used to bias the rocking lever 39.

Rotor disc 56 and stop shaft 38 control the energized time of the associated appliance by actuating rocking lever 39 to change the electrical condition of switch 24 at the end of a preselected timing interval. This function is provided in response to a setting step which requires only file 102 energized time setting is simplified, and the desirable feature of having the unexpired time of the preselected interval continuously indicated is provided.

Rotor disc 56 is mutilated gear, having a predetermined portion 94 free of teeth in order to provide an inoperative position for the stop shaft, which in the case of an electric or gas range timer is usually labeled manual, indicating that the range is set for completely manual control by the operator. In the manual position, the teeth of the idler gear 80- do not engage the mutilated gear 56, and thus no rotation is imparted to the mutilated gear 56.

As hereinbefore stated, the stop shaft 38 and rotor disc or mutilated gear 56 may be set to the desired time or energized interval without depressing the shaft axially. The stop shaft '38 is rotated until the indicator 96 attached to the shaft points to the desired time interval on an associated dial. As soon as shaft 38 and mutilated gear 56 are moved from the manual position, the portion 94 of the mutilated gear 56 which has no teeth is advanced past the idler gear 80*, and the teeth of the mutilated gear engage the teeth of the idler gear 80'. The yieldable spring loaded arrangement for idler gear 80 allows rotation of the rotor disc 56 to a preselected time interval without rotation of idler 80', which is locked into the gear train driving the idler gear 80. Manual rotation of the mutilated gear 56 pushes the idler gear 80 away from the mutilated gear, enabling the co-acting teeth of the two gears to mesh and demesh as the mutilated gear 56 is rotated to the desired angular position. Thus, the yieldable spring loading of idler gear 80 enables the stop shaft 38 and mutilated gear 56 to be set with only a rotary motion of the stop shaft. Once set to a preselected time interval, mutilated gear 56 will rotate under the influence of idler gear 80', assuming of course that any time delay interval set by the start shaft 36 has expired. The mutilated gear 56 will rotateggntil the portion 94 without teeth reaches the idler gear Rotation of the mutilated gear 56 is transformed to a pivotal movement of rocking lever 39, by providing a predetermined cam profile on the face 100 of mutilated gear 56, which face is adjacent to the rocking lever 39. First and second similar cam profile arrangements 102 and 104 are provided, 180 apart on the surface or face 100 of the mutilated gear 56, on opposite sides of the rotational axis. The two cam profiles 102 and 104 are placed on different diameters, as illustrated in FIG. 2, with cam profile 102 being placed on the larger of the two diameters, indicated by the broken circle 106, and the cam profile 104 is placed on the smaller of the two diameters, indicated by the broken circle 108. This arrangement provides a single time interval for a complete revolution of the mutilated gear 56.

A cross-sectional view of cam profile 104 is illustrated in FIG. 6. Cam profile 104 includes a trough or depression 110 formed in the face of the mutilated gear 56, which has a wall 112 at one end of the depression which is substantially perpendicular to the face 100 of the multilated gear 56, and which extends downwardly to the bottom 115 of the depression. The depression 110 slopes upwardly from the bottom 115, away from the wall 112, providing a ramp 116 which continues beyond the surface 100 of the multilated gear by a predetermined small dimension, as will be hereinafter explained. The ramp 116 slopes away from the surface 100 at a predetermined angle 118, such as about 30".

Cam profile 102 is substantially similar to cam profile 104, differing only because the cam followers associated with the two cam profiles, while being lifted by the same vertical dimensions, make their vertical lift over different circumferential dimensions. Thus, angle 118 in cam prowould be less than the angle associated with cam profile 104, such as about 25.

Interval timer includes a new and improved rocker lever 39 which actuates switch operator 37 in response to rotation of the rotor disc 56. Rocker lever 39, best shown in FIGS. 3, 4 and 5 which are side elevation, plan, and right end elevation views, respectively, reduces the number of frictional contact points in the assembly which translates movement of the cam surface of rotor disc 56 to actuation of the switch operator, by providing first and second

cam follower members

122 and 124, respectively, which are integral, depending portions of the rocker lever 39.

Cam follower members

122 and 124 depend from, or extend perpendicularly outward in the same direction from end 57 of the rocking lever 39.

More specifically, rocking lever 39 includes a flat, elongated, main body portion 126 having first and second ends 57 and 59, respectively, first and second sides or

edges

128 and 130, respectively, and first and second flat, parallel, major

opposed surfaces

132 and 134, respectively.

Indentations

136 and 138 are provided in

sides

128 and 130, respectively, for receiving locating or restraining ears which cooperate with the fulcrum 52 to allow pivotal movement of the rocking lever 39.

Cam follower members

122 and 124 depend from, or extend perpendicularly outward from, major side 134 at end 57 of the rocker lever 39. Rocker lever 39 may be cut to shape from a flat sheet of metallic material, and the cam follower members may then be bent into the required spaced relation, perpendicular to the main body portion 126. As best illustrated in FIG. 5, the

cam follower members

122 and 124 are spaced from a centerline 140 by

dimensions

142 and 144, respectively, which dimensions are not equal to one another since the cam followers are designed to follow different diameter circles on the face of the rotor disc 56 as it rotates.

Constructing the rocking lever 39 with integral

cam follower members

122 and 124 eliminates a separate cam follower assembly which would have to be slidably disposed on a shaft mounted through the rotor disc, which thus eliminates the sliding contact between a separate cam follower assembly and its cooperative shaft. The

cam follower members

122 and 124 of rocking lever 39 extend through support plate 12 without making contact therewith, since the rocking lever 39 is supported by its fulcrum 52 and the contacts between its cam follower members and surface 100 of the rotor disc 56. A separate cam follower assembly would be slidably disposed through the support plate 12, in order to guide and maintain the location of the separate cam follower assembly. Thus, the disclosed rocking lever 39 eliminates any sliding contact between the cam follower assembly and support plate. The elimination of these frictional contact points reduces the torque required to rotate the stop shaft 38 when it is desired to set the energizing time of an associated appliance, it reduces the load on the motive means when the appliance is under automatic control, it simplifies the manufacture and assembly of the interval timer 10, and it reduces its manufacturing cost.

The rocking lever 39 is also constructed to rotate the rotor disc 56 by a predetermined angle at the termination of the energizing time, to move the associated pointer 96 to zero with a positive action that provides a clear demarkation from the pointer position just prior to termination of the energizing time, and the pointer position following the termination of the energizing time. Either or both of the cam followers may be constructed to provide this desirable function, but since the function may be performed by one cam follower, it is illustrated in the figures associated only with the cam follower member 124.

More specifically, the edge of the selected cam follower which is adjacent to the vertical wall 112 of the cam profile when the cam follower is biased into the depression, is provided with a surface which has a predetermined angle relative to this edge, which surface makes sliding contact with the edge of the depression as the cam follower is biased therein, moving the rotor disc 56 an angular dimension depending upon the perpendicular distance 152 between the start of this surface at the extreme end of the cam follower member and the side of the cam follower member which the surface intersects. If cam follower 122 is selected to provide this positive zero return function, the leading edge of the cam follower, i.e., the edge which is at the extreme end 57 of the rocking lever 39 would be provided with this angular surface. If cam follower 124 is selected, as illustrated in the figures, the trailing edge of the cam follower, i.e., the edge opposite to the one at the extreme end 57 of the lever 39, would be provided with this surface.

Since cam follower 122 is not selected to provide the return to zero function, its leading edge adjacent its extreme end may be cut back, as illustrated best in FIG. 3, to provide a surface 149 which is parallel with the leading edge 151 of the cam follower, but stepped inwardly therefrom. Its trailing edge will ride up the ramp of its associated cam profile when the stop shaft is manually returned from its zero position to the manual position, and thus is curved or rounded adjacent its extreme end, as illustrated at 153.

Cam follower 124 has its trailing edge 157 provided with angular surface 155, which starts at the extreme outer end of the cam follower, adjacent the point of contact of the cam follower with the face of the mutilated gear 56, with the start of the surface 155 being a predetermined dimension 152 from edge 157, and it extends to edge 157 making a predetermined acute angle 150 therewith. The magnitude dimension 152 determines the rotational angle imparted to the rotor disc 56 as the cam follower 124 drops into depression 110.

Since the leading edge 159 of cam follower 124 will ride up the ramp 116 when the stop shaft G38 is returned to its manual position, this edge is curved or rounded adjacent the extreme outer end of the cam follower as illustrated at 160.

The

cam followers

122 and 124 are biased to the face 100 of mutilated gear 56, with the

cam follower members

122 and 124 being oriented to ride on the diameters indicated at 106 and 108, respectively, on the face of the mutilated gear 56. The rocking lever 39 and its cam followersare biased against face 100 of the mutilated gear 56 by the U-shaped spring member and thus the rocking lever 39 pivots about its fulcrum 52 in response to the profile of the cam arrangements 102 and 104.

In the manual position of the mutilated gear 56, the rocking lever 39 and its

cam follower members

122 and 124 are biased to the face 100 of the mutilated gear 56, in the position illustrated in FIG. 10. In this position, end 57 of the rocking lever 39 is moved or pivoted to an upper position, overcoming the bias provided by spring 55 and pivoting the rocking lever 39 about its fulcrum 52. If a delayed start feature is used and set, as illustrated in FIGS. 1 and 6, the rocking lever 39 at this point will be substantially parallel with the support plate 12, as it will also be supported at its end 59 by portion 68 of the start shaft. The

cam followers

122 and 124 are located in the manual position of stop shaft 39 by spaced protuberances 162 and 164 illustrated relative to cam profile 104 in FIGS. 6 through 10, which protuberances are separated by a' space 166. Protuberance 162 may be a continuation of ramp 116, as illustrated. Rotating the stop shaft 38 clockwise, when viewing the knob end of the shaft, to cause the

cam follower members

122 and 124 to rise over both of the protuberances adjacent thereto, engages the teeth of the mutilated gear 56 with those of the idler gear 80, and rotation of shaft 38 may then be continued until the pointer 96 associated with shaft 38 selects the desired time interval the associated electrical apparatus is to be energized.

FIG. 6 is a fragmentary view, partially in section, which illustrates the start shaft set to provide a time delay, indicated by the shaft 68 being in its uppermost position, which lifts end 59 of rocking lever 39 to its uppermost position. The stop shaft 38 has also been moved from the manual position shown in FIG. 10, and the cam follower no longer rests between the protuberances, such as between protuberances 162 and 164. When the delay interval set by the start shaft 36 times out, shaft 68 drops to its lowermost position, as shown in FIG. 7, and the mutilated gear 56 is then rotated until the

cam follower members

122 and 124 reach the depressions or troughs associated with their cam profiles 102 and 104.

FIG. 8 illustrates cam follower 124 at the termination of the timed energization period, just as it is entering the depression 110. The angular surface 155 'on cam follower 124 causes mutilated gear 56 to continue to rotate as the rocking lever 39 pivots in a clockwise direction about fulcrum 52, advancing gear 56 by a predetermined number of degrees from its position at the termination of the timed interval, and FIG. 9 illustrates the cam follower124 at rest in the depression 110 of the cam profile 104. The pivoting rocking lever 39 actuates the switch operator 37 and changes the electrical condition of the switch 24.

Resetting the stop shaft to the manual position requires that the stop shaft 38 be rotated a few degrees in a clockwise direction, when facing the knob end of the shaft, to force the cam followers up the ramps of their associated cam profiles, and the shaft rotation is terminated when the

cam follower members

122 and 124 are located between their associated protuberances, as illustrated in FIG. 10. These protuberances are formed such that the first protuberance 162 has a smaller height dimension than the second protuberance 164, in order to quickly and accurately turn the stop shaft to its manual position. The rotation of the stop shaft 38 to force the cam followers out of the trough or depression positions of the cam profile to the manual position of the stop shaft is insufficient to engage the teeth of the mutilated gear 56 with the idler gear.

80, retaining the stop shaft and mutilated gear 56 in a deenergized position. This movement of the stop shaft, however, changes the electrical conditions of the switch 24, due to the rising of the cam followers out of the depressions, with the resulting electrical condition of the switch 24 permittingmanual control of the associated appliance. This also enables the delayed start function to be used without setting a predetermined stop time, by' setting the delayed start shaft and leaving the stop shaft in its manual setting.

As illustrated in FIGS. 6 and 7, when the delayed start feature is set, and shaft 68 raises end 59 of the rocking lever 39, the rocking lever 39 is lifted from its fulcrum 52 and the electrical switch condition is such that the electrical appliance is deenergized. When the delayed start feature times out and shaft 68 drops, the rocker lever 39 drops to its fulcrum 52, actuating the electrical switch to start the energizing time of the appliance. At the termination of the energizing time, the cam followers are biased into the depressions of the cam profiles, again actuating the electrical switch to terminate the energization of the appliance. In the event the delayed start feature is not required, the start shaft 36 would not be required and the gears 64 and 66 would be locked together in the position shown in FIG. 2.

In the operation of the interval timer 10, it will be assumed that the timer is being used with a range. To use the automatic features, the housewife simply sets the oven thermostat to the desired oven temperature, pushes the start shaft 36 and rotates it in either circumferential direction to the desired time delay interval, and rotates the stop shaft 38 clockwise to the cooking time desired. The clock mechanism 20 drives the lower gear 64 of gear assembly 54 until the nose 72 thereon is aligned with the aperture 74 in the upper gear 66, at which time the complete assembly 54 rotates, imparting rotation to the idler gear and the mutilated gear 56. The mutilated gear 56 turns until its cam followers drop into depressed portions of the cam profiles, actuating the switching to terminate the cooking time.

In summary, there has been disclosed a new and improved interval timer for an appliance, having an improved and simplified control for automatically terminating the energization time of the appliance. The control for selecting the energizing time interval need only be rotated to the selected time without requiring that the shaf be axially depressed. A single rocking lever member functions as a cam follower and as the pivotal lever for actuating the switch operator, reducing the number of frictional locations in the assembly to a minimum, which minimizes the torque required to set the stop shaft, and minimizes the drag on the motive means as the preset time is being timed out. The rocking lever includes a cam follower which is constructed to rotate the associated pointer by a predetermined number of degrees at the end of the timed cycle, to provide a positive demarkation between the position of the pointer just prior to the termination of the preselected cycle, and the position of the pointer when the cycle has terminated.

We claim as our invention:

1. A timing device comprising:

a stator structure,

a rotor disc mounted for rotation about an axis relative to said stator structure,

a control shaft connected to said rotor disc,

a predetermined continuous portion on a face of said rotor disc defining a first arcuate path including a predetermined cam profile spaced from said face and extending arcuately from one end of said first arcuate path, and further defining a second arcuate path extending between said one end and the other end of said first arcuate path,

a rotating motive means having a regular rate of rotation,

a switch operable between open and closed positions,

means for actuating said switch including a lever mounted for pivotal movement on said stator structure, one end of said lever operating said switch and the other end having integral cam follower means depending therefrom so as to be oriented to be movably responsive to the face portion and to the cam profile, means biasing said lever against said rotor disc such that its integral cam follower means is biased against the predetermined face of said rotor disc such that when the cam follower means is positioned at said one end of said first arcuate path said switch is placed in one of said positions and when positioned along the second arcuate path said switch is placed in the other of said positions,

means slectively coupling and decoupling said motive means to said rotor disc in response to the rotational positions of said rotor disc such that said motive means is coupled to said rotor disc when said cam follower means is located against said second arcuate path and drives said one end of said first arcuate path directly toward said cam follower means, and further such that said motive means is decoupled from said rotor disc when said cam follower means is located against said one end of said first arcuate path,

and said cam follower means including surface toeffect predetermined rotation of said rotor disc upon said cam follower means reaching said one end of said first arcuate path, whereby said control shaft is positionable to orient said second arcuate path relative to said cam follower means at a corresponding predetermined time interval for actuating said switch between said other and said one positions and for having positive rotational displacement of said con- 10 trol shaft upon reaching the end of the desired time interval.

2. The timing device of claim 1 including indicating means fixed to the control shaft for indicating the time interval remaining before the switch is actuated, and said surface advancing the indicating means by a predetermined number of degrees as the cam follower means enters and comes to rest at said one end of said first arcuate path.

3. The timing device of claim 2 wherein the means for advancing the indicating means as the cam follower means enters the one end of said first arcuate path includes an angular surface oriented to provide a predetermined angle between the portion of the cam follower means which rests against the face of the rotor disc, and a predetermined edge of the cam follower, such that said angular surface slides over an edge of the cam profile as the cam follower means drops therein.

4. The timing device of claim 1 wherein the predetermined face of the rotor disc includes first and second sets of first and second arcuate paths disposed on opposite sides of the axis, with the first and second sets being on first and second different radii relative to the axis, respectively, and the cam follower means includes first and second spaced follower members oriented to contact the predetermined face of the rotor disc at said first and second different radii, respectively.

5. The timting device of claim 4 wherein one of the spaced follower members include an angular surface for rotating the rotor disc by a predetermined angle upon said follower member reaching its associated one end of a first arcuate path.

6. The timing device of claim 5 wherein the motive means for rotating the rotor disc as the follower member reaches its associated one end of a first arcuate path, includes an angular surface which extends from the portion of the follower member which contacts the face of the rotor disc to a predetermined edge of the follower member, which angular surface is oriented such that the angular surface contacts the edge of the one end as the follower member is biased into the depression.

7. The timing device of claim 1 wherein the motive means includes a start member mounted for rotation about an axis relative to the stator structure which has first and second axial positions, and means selectively coupling and decoupling said start member in driving relationship between motive means and said rotor disc such that when said start member is in the first axial position and rotationally set for approaching a preselected interval starting time the motive means is effectively decoupled from the rotor disc, and when the start member reaches the second axial position in response to arrival at said preselected starting time, which position enables the rotor disc to be coupled with the motive means.

References Cited UNITED STATES PATENTS 3,031,590 4/1962 Johnson et al. 20038 C X 3,436,498 4/1969 Murray et al. 20038 BA 3,118,981 1/1964 Zoppoth 200-38 C 3,475,899 11/1969 Boyles 20038 FB X 2,424,116 7/1947 Puerner 20038 B 3,596,015 7/ 1971 iI'ullien-Davin 20038 BA X J. R. SCOTT, Primary Examiner US. Cl. X.R.