CA1153455A - Electrical switch operating timing mechanism - Google Patents

Electrical switch operating timing mechanism

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Publication number
CA1153455A
CA1153455A CA000419372A CA419372A CA1153455A CA 1153455 A CA1153455 A CA 1153455A CA 000419372 A CA000419372 A CA 000419372A CA 419372 A CA419372 A CA 419372A CA 1153455 A CA1153455 A CA 1153455A
Authority
CA
Canada
Prior art keywords
cam
drum
timing mechanism
helical cam
shaped helical
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000419372A
Other languages
French (fr)
Inventor
Maurice E. Schuder
Richard W. Stafford
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Emhart Industries Inc
Original Assignee
Emhart Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/148,714 external-priority patent/US4327259A/en
Application filed by Emhart Industries Inc filed Critical Emhart Industries Inc
Priority to CA000419372A priority Critical patent/CA1153455A/en
Application granted granted Critical
Publication of CA1153455A publication Critical patent/CA1153455A/en
Expired legal-status Critical Current

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Abstract

ELECTRICAL SWITCH OPERATING TIMING MECHANISM

ABSTRACT OF THE DISCLOSURE

A timing mechanism comprising a drum-shaped helical cam. The drum-shaped helical cam is connected for power driven rotation. A cam follower engages the drum-shaped helical cam. At least one electrical switch is opened and closed by the cam follower. A
manual actuator element cooperates with the helical cam to cause relative axial movement between the helical cam and the cam follower.

Description

~3~S~
BACKGROUND OF THE INVENTION
Generally speaking, the present invention pertains to improvements in a timing mechanism wherein coupled drum wheels of a digital interval timer are rotatably set at a predetermined period of time, wherein at least one cam having a notch opening to an outer periphery of the cam is rotatably coupled to at least one of the drum wheels;
and wherein an actuator means engages the cam to open and close an electrical switch, the switch opening when the actuator means drops into the notch; an improvement charac-terized by the actuator means including a pivoting member pivotally mounted with respect to the notch, the pivotally mounted mernber and the notch provide means such that a resultant force vector between the notch and the pivoting member when they are engaged is in a direction away from the notch and means wherein the drum wheels may be rotated in either direction after the electrical switch has been opened.
Another improvement relates to a means providing an auxiliary program for the mechanism which, in general, comprises a drum shaped helical cam, means applying power driven rotation to the drum shaped helical cam, a cam follower engaging the drum shaped helical cam, at least one electrical switch opened and closed by the cam follower, and actuator means causing relative movement between the helical cam and the cam follower.
The present invention relates to a timing mechanism and more particularly to a timing mechanisrn using a digital interval timer.

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Timing mechanisms utilizing digital interval timers have been used for many years in appliances such as ovens and ranges and in recent years in appliances such as microwave ovens.
In most, if not all of such applications, d~um wheels having coded indicia to indicate time are rotatably coupled together through commonly ~sed geneva gear drives. Also cams are usually coupled to the drum wheels for rotation w;th the wheels to open and close electrical switches. Such cams usually employ a notch to actuate a cam follower with the cam follower falling into the notch. One of the problems with such an arrangement is that of being unable to rotate the drum wheels in either direction when the cam follower is in the notch. This then causes the operator, in many instances, to rotate the drum wheels many turns when a new time needs to be set.
In microwave oven applications, it has been found to be, at times, necessary to provide an auxiliary program in addition to the normal program usually required for cooking times. More specifically, it has been found to be highly desirable, if not necessary, to vary the power to the magnetron of the microwaven oven during certain cooking time periods.
The type of timing mechanisms discussed herein also have a "packaging problem" in that they are inherently complicated and therefore somewhat difficult to assemble.
The present invention is directed to features of digital interval timing mechanisms which solve these problems.
FEATURES OR OBJECTS OF THE INVENTION
Accordingly, it is a feature of the invention to provide a timing mechanism wherein drum wheels provide a digital interval timer and wherein cams are coupled to the drum wheels to actuate cam followers to open and close electrical switches. Another feature of the invention is to provide for such a timing mechanism wherein the drum wheels may
-2-~3~53~S5i be rotated in either direction even ~hen the cam follower drops in the notch. Another feature of the invention is the provision of such a timing mechanism wherein the notch and the cam follower are constructed and arranged so that the resultant force vector between the notch of the rotating cam and the cam follower when they are engayed is in a direction away from the notch regardless of the direction of the cam's rotation.
Still another feature of the invention is the provision of such a timing mechanism where there is a means to provide an auxiliary program other than the normal program of the timing mechanism. Yet another feature of the invention is the provision of such a timing mechanism wherein such means includes a drum shaped helical cam, a cam follower, means to provide relative axial movement between the drum shaped helical cam and the cam follower. Another feature of the invention is the provision of such a timing mechanism wherein power driven rotation of the drum shaped helical cam is provided by the same means that provide power driven rotation to the drum wheels.
Another feature of the invention is the provision of such a timing mechanism wherein the elements of the mechanism are packaged within a housing such that the mechanism is relatively easy to assemble. Another feature of the invention is the provision of such a timing mechanism wherein the housing includes a cup shaped member with an open end with ribs in its side walls to receive a frame carrying the drum wheels and the drum shaped helical cam. Yet another feature of the invention is the provision of such a timing mechanism wherein apertures are provided in the cup shaped member to receive electrical terminals carried by the cup shaped member and at least one output member of a motor drive carried by the cup shaped member.
These and other features of the invention will be apparent from the following description taken in conjunction with the accompanying .
drawings.

i3~;i.5 DETAILED DESCRIPTIUN OF THE DRA~JINGS
Figure 1 is an exploded view of a timing mechanism employing the features of the invention.
Figure 2 is a top view of the mechanism in partial cross-section.
Figure 3 is an end view of the timing mechanism in partial cross-section.
Figure 4 is a view taken along the line 4-4 of Figure 3.
DESCRIPTION OF THE I~IVENTION
Referring now to the drawings, there is shown a timing mechanism 10 employing the features of the invention. In general, the timing mechanism includes a plurality of drum wheels 11, 12 and 13 rotatably carried on a shaft 14, a plurality of cams 16, 18 and 20 carried on shaft 14 and coupled to the individual drum wheels, cam followers 22, 24 and 26 which are actuated by the cams to open and close electrical switches in a manner well known 1n the art. Each of the drum wheels has coded indicia on their outer periphery to indicate time periods. In the present embodiment, drum wheel 11 indicates tens of minutes, drum wheel 12 indicates minutes and drum wheel 13 indicates seconds. The drum wheels are coupled together such that drum wheel 13 drives drum ~Jheel 12 and drum wheel 12 drives drum wheel 11 through individual geneva drives 34, 38, 41 and 42 carried on shaft 14, and 36 and 40 carried on shaft 15. The operation of geneva drives are well knowr, in the art and since the drum wheels and their geneva drives do not form part of the invention, a detailed description and drawings have been omitted for the sake of simplicity.
As better shown in Figure 2, power driven rotation is applied to the drum wheels from motor 44, through gear train 46 to an output pinion 48 to a gear 50 which is rotatably carried on shaft 52 and fixedly connected to face gear 54 which in turn engages gear 56 which is intergral with drum wheel 13. A desired cooking cycle may be set by axially indexing , ~53~5~
shaft 52 "in" to move face gear 54 out o~ engagement ~Jith ge~r 56 against spring 55 and move face gear 58 into engagement ~lith gear 56 ~nd rotating the shaft. A~ter setting the drum wheels, shaft 52 is released and face gear 54 again engages 56 through the expansion o~ spring 55. Spacer 60 separates face gears 54 and ~8. A thumb wheel 62 provided on drur, wheel 11 reduces the number of setting rotations of shaft 52.
Cams 16, 18 and 20 are substantially the same and therefore the description w~th regard to cam 16 of Figure 3 and cam 18 of Figure 4 applies to cam 20. Each of the cams are carried on an individual drum wheel, cam 16 on drum wheel 113 cam 18 on drum wheel 12 and cam 20 on drum wheel 13. As shown, each of the cams includes an outer periphery 16' and a notch 16" open;ng to the outer periphery. Cam followers 22, 24 and 26 (Figure 1) engage cams 16, 18 and 20, respectively through V-shaped followers 22', 24' and 26'. The cam followers are carried on a sleeve 28 which is rotatably carried on a shaft 30. Since the followers act as a unit in that a switch is only to be opened or closed when a certain time period is met, all three followers will be in the same mode at a given time. At any particular time, switch actuator 32 of follower 24 actuates blades 25 and 27 to open or close an electrical circuit to terminals 32' and 32" (Figure 2) to provide a program sequence. As shown in Figure 4, cam follower 24 is spring biased toward cam 16 by spring 31 which is attached to the follower and to plate 33 to provide a fast drop of the cam follower into notch 16". Since cam followers 22, 24 and 26 are all carried on sleeve 28, cam followers 24 and 26 are also pro\lidè~ with a fast drop from the action of the spring 31.
As better shown in Figure 3, an alarm means 35 is associated with cam fo~lower 22 to provide an alarm when the follower drops into notch 16". Alarm means 35 includes a bell 37 and hammer 39 which is pivotaly mounted on cam follower 22 at pivot 41 and which is spring biased against the cam follower through coil spring 43 that is biased against a side 45 ~5345~
of the cam follo~,ler. ~Ihen the cam follower drops into notch 16", the side 45 o-f the follower forces the hamlller to pivot and strike the bell.
According to a feature of the invention, the cam followers and the notches 16" of the cams are in operable relation to each other so that drum wheels 11, 12 and 13 may be rotated in either direction even though the cam followers have dropped into the notches. More specifically, notches 16" and the cam followers are V-shaped and the pivot point of the cam followers, that is shaft 30, are in plane opposite the opening of the notches when the cam followers are engaged in the notches. This 10 results in a resultant force vector between the notch of the rotating cam and the cam follower when they are engaged that is in a direction away from the notch regardless of the direction of cam rotation.
With reference to Figures 1 and 2, according to another feature of the invention, an auxiliary program is provided by another program means 70. Program means 70 includes a drum shaped helical cam 72 that is axially slideable on shaft 74, the cam being rotatable with the shaft through the shafts flat portion 76. Power driven rotation is applied to shaft 74 from motor 44 through g-ear train 46 to output pinion 78 of the gear train wh;ch engages face gear 80, face gear 80 being fixed1y carried 20 on the shaft. There is a small amount of axial "play" in shaft 74 so that engagement between the face gear and pinion 78 can~be insured through spring 82 that is biased between the face gear and plate 84. Thus drum wheels 11, 12 and 13 with their respective cams 16, 18 and 20 and helical cam 72 are rotatably driven off the same power source. Helical cam 72 includes a helical cam lobe 72' which engages cam follower 86 which is pivotaly mounted on shaft 30. The helical cam may be manually axially moved on shaft 74 to provide a desired setting of cam lobe 72' with respect to cam follower 86. Such manual setting is accomplished by actuator means 88.
Actuator means 88 includes a slider composed of a block 92 slideably carried in a slot 94 of a front plate 33, a handle 98 to manually move the block, ~3~5~

and a yoke 100 extending from the block and engdging a groove 102 provided in helical cam 72. Manually axially moving the slider sets the position of the helical cam with respect to cam follower 86.
Rotation of cam 72 causes cam follower 68 to open and close electrical circuits to switches 104 and 106 (Figure 2) through a switch actuator block 108 (Figure 1) attached to the cam follower and having two lobes 110 and 112 for engaging contact blades (not shown). Thus an auxiliary program is provided for the timing mechanism.
Another feature of the invention pertains to the manner in which the timing mechanism is packaged. As will be apparent, the mechanism is packaged so that the unit as a whole is very easy to assemble. Referring in particular to Figures 1 and 2, the timing mechanism is enclosed in a housing which includes a cup shaped plastic member 120 having a base portion 122, a pair of end sidewalls 124 and 126, a pair of side walls 123 and 125, and a plate 96 closing the open end of the cup shaped member.
Plate 33 has an opening 128 through which drum wheels 11, 12 and 13 protrude.
Two pairs of opposed ribs, 130 and 132, are provided in the opposed side walls 123 and 125 (half of each pair shown). In each rib there are slots 134 and 136 provided in the ribs (half of each pair shown) for receiving plates 84 and 84'. As better shown in Figure 1, plates 84 and 84` provide frames for receiving shafts 14, 15 and 74 with their associated mechanism. Plate 84 is located between the end walls while plate 84' is formed as part of an end wall. To assemble the timing mechanism, the various elements are first assembled on their respective shafts and the shafts are inserted in apertures 138, 140, 142, 144 of plate 84 then the shafts are inserted in corresponding apertures of plate 84" to form a single modular unit. The plates are then inserted in the slots and then 33 96 is positioned to close the open end of the cup shaped member.

~S3~S5 Base portion 122 of cup shaped memher 120 carries motor 44 and gear train 46 as well as electrical terminals 32', 104 and 106 and bell 35 these being apertures 146 in the base portion to receive at least one output member of the gear train.

This is a division of Canadian patent application Serial No. 365,079 filed November 20, 1980.

,

Claims (7)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A timing mechanism comprising a drum shaped helical cam, means applying power driven rotation to said drum shaped helical cam, a cam follower engaging said drum shaped helical cam, at least one electrical switch opened and closed by said cam follower, and manual actuator means cooperating with means on said helical cam causing relative axial movement between said helical cam and said cam follower.
2. A timing mechanism according to claim 1 wherein said drum shaped helical cam is slidably carried on a shaft and said actuator means causes said drum helical cam to move axially along said shaft.
3. A timing mechanism according to claim 2 wherein said actuator means includes a slider carried in a frame for said timing mechanism and engaging said drum shaped helical cam.
4. A timing mechanism according to claim 3 wherein said drum shaped helical cam includes a groove receiving said slider.
5. In a timing mechanism wherein coupled drum wheels of a digital interval timer are manually rotatably set at a predetermined period of time; wherein a first drive means provides power driven rotation to said drum wheels; and wherein cam means providing a program sequence are coupled to said drum wheels to be rotated therewith and open and close first electrical switches operably associated with said cam means; means opening and closing second electrical switches to provide an auxiliary program comprising:
a) a drum shaped helical cam, b) second drive means applying power driven rotation to said drum shaped helical cam, c) a cam follower engaging said drum shaped helical cam, and d) manual actuator means cooperating with means on said helical cam causing relative movement between said helical cam and said cam follower.
6. In a timing mechanism according to claim 5 wherein said first and second drive means are connected together.
7. In a timing mechanism according to claim 6 wherein the connected drive means includes a motor and a gear train coupled thereto said gear train having two output members.
CA000419372A 1980-05-12 1983-01-12 Electrical switch operating timing mechanism Expired CA1153455A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA000419372A CA1153455A (en) 1980-05-12 1983-01-12 Electrical switch operating timing mechanism

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US06/148,714 1980-05-12
US06/148,714 US4327259A (en) 1980-05-12 1980-05-12 Timing mechanism
CA000365079A CA1149924A (en) 1980-05-12 1980-11-20 Electrical switch operating timing mechanism
CA000419372A CA1153455A (en) 1980-05-12 1983-01-12 Electrical switch operating timing mechanism

Publications (1)

Publication Number Publication Date
CA1153455A true CA1153455A (en) 1983-09-06

Family

ID=27166892

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000419372A Expired CA1153455A (en) 1980-05-12 1983-01-12 Electrical switch operating timing mechanism

Country Status (1)

Country Link
CA (1) CA1153455A (en)

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