CA1155160A - Timing mechanism having a short pulse prior to its overall program - Google Patents

Timing mechanism having a short pulse prior to its overall program

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Publication number
CA1155160A
CA1155160A CA000379317A CA379317A CA1155160A CA 1155160 A CA1155160 A CA 1155160A CA 000379317 A CA000379317 A CA 000379317A CA 379317 A CA379317 A CA 379317A CA 1155160 A CA1155160 A CA 1155160A
Authority
CA
Canada
Prior art keywords
cam
ramp
single cam
shaft
engaging
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
CA000379317A
Other languages
French (fr)
Inventor
Donald L. Ray
Elmo Voland
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 US06/205,737 external-priority patent/US4348560A/en
Application filed by Emhart Industries Inc filed Critical Emhart Industries Inc
Application granted granted Critical
Publication of CA1155160A publication Critical patent/CA1155160A/en
Expired legal-status Critical Current

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Abstract

TIMING MECHANISM HAVING A SHORT
PULSE PRIOR TO ITS OVERALL PROGRAM

ABSTRACT OF DISCLOSURE
A timing mechanism which comprises a shaft, an integrally con-structed first ramp and a locator for positioning the first ramp which is rotatably carried by the shaft, a clutch comprising a clip ring coupled to the integrally constructed first ramp and locator and functionally engaging a boss through which the shaft extends, a single cam slideably carried on the shaft and a coupler coupling the single cam to the shaft for rotation therewith, a spring axially biasing the single cam, a second ramp coupled to the single cam and engaging the first ramp to selectively axially displace the single cam in a predetermined direction, first and second cam followers engaging the single cam to be sequentially actuated in accordance with an axial displacement of the single cam, and a switch opening and closing in response to the cam followers, and a release permitting the single cam to axially displace past the cam followers to its original position.

Description

5~0 BACKGROUND OF THE INVENTION
Generally speaking, the present invention relates to a timing mechanism which comprises a shaft means, integrally constructed first ramp means and locator means for positioning the first ramp means rotatably carried by the shaft means, clutch means comprising a clip ring coupled to the integrally constructed first ramp means and locator means and functionally engaging a boss through which the shaft means extends, a single cam slideably carried on the shaft means and coupling means coupling same to the shaft means for rotation therewith, spring means axially biasing the single cam, second ramp means coupled to the single cam and engaging the first ramp means to selectively axially displace the single cam in a predetermined direction, first and second cam followers engaging the single cam to be sequentially actuated in accordance with an axial displacement of the single cam, and switch means opening and closing in response to the cam followers, and release means permitting the single cam to axially displace past the cam followers to its original position.
The invention pertains to a timing mechanism, and more particularly to a timing mechanism wherein there are means for providing a pulse of very short duration prior to an overall program of the timing mechanism.
Timing mechanisms are extens~vely used in the appliance industry to control the funct~ons of an applinace in accordance with a predetermined program. For example, they are extensively used in washers, dryers, dishwashers, and microwave ovens. In some of the applications, the need arises for a short pulsing cycle to be operable within or separate from an overall program. In microwave ovens, for example, such a short pulse is sometimes needed to intermittently apply electrical power to its magnetron. When such power is initially applied to the magnetron, a llS5160 very high current surge is imposed on the circuit. The surge then drops off. Therefore, there is also a need in this application to provide an even shorter pulse whereby current can be initially switched through a current limiting resistor. The present invention provides a means for achieving short pulses in a very simple and economical manner.
OBJECTS OR FEATURES_OF THE INVENTION
It is, therefore, a feature of the invention to provide a timing mechanism having a means to provide short pulsing cycles in addition to an overall program. Another feature of the invention is the provision of such a timing mechanism wherein the short pulses are initiated by a pair of cam followers sequentially dropping from a cam periphery. Still another feature of the invention is the provisions of such a timing mechanism wherein the cam followers sequentially drop from the cam's periphery in response to an axial displacement of the cam.
Another feature of the invention is the provision of such a timing mechanism wherein the axial displacement of the cam is provided by a first ramp carried by ,the cam engaging a second ramp to be actuated thereby. Yet another feature of the ;nvention is the provislon of such a timing mechanism wherein there is a means to locate the second ramp in a predetermined position so as to initiate and terminate the short pulse according to a predetermined time period. Another feature of the invention is to provide such a t~ming mechan;sm wherein there is a clutch means permitting manual setting of a locator means for the second ramp.
Another feature of the invention is to provide such a timing mechanism wherein the clutch means comprises a clip ring. Another feature of the invention is the provision of such a timing mechanism wherein there is a release means permitting the cam to be axially displaced and return past the cam followers to its original position upon completion of the program. These and other features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings.

llSS~60 DESCRIPTIO'~ OF THE DRAWI_GS
Figure 1 is a section of the timing mechanism employing the principles of the invention.
Figure 2 is an exploded view of the timing mechanism.
Figures 3A through 6B are similar views in partial section showing different operating stages of a cam means of the timing mechanism.
Figure 7 is an exploded view taken along the line 7-7 of Figure
2 showing another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
~ Referring to the drawings, there is shown a timing mechanism - - 10 employlng the features of the invention. In general~, timing mechanism 10 includes a cam means 12, switch means 14 responslve thereto through cam followers 16 and 18, and motor drive means 20 which applies power driven rotation to the cam means. The motor drive means includes a ;~ synchronous motor and a gear train, both of which are well known in the art and therefore not shown.
:: : . ., Cam means 12 includes a cam 24 having a step 26 in its outer periphery, and a ramp means 28 extending from a face of the cam at the step. The cam is coupled to the gear train of the motor for rotation therewith through coupling means 30. Coupling means 30 also permits the cam to be axially displaced and ~ncludes a square aperture 32 provided in the cam and a basically square shaft 34 which mates the aperture.
Shaft 34 serves as the output pinion of the gear train of the motor.
Its opposed end is journalled for rotation about an end of shaft 36 (end not shown). As will be hereinafter described, cam 24 rotates with shaft 34 and is axially displaceable thereon. The cam is axially spring biased through coil spring 40 which is held between the cam 24 and disk 42 which is held against plate 43 carried by housing 44 of the timing mechanism. Ramp means 28 includes a V-shaped tab 38, to provide two r~mp surfaces.

_ ....... .. ... ..... ..
:

1~551~

Switch means 14 (Figure 1) includes contact blades 46, 48 and 50, each integral or otherwise coupled to electrical terminals 46', 48' and 50'. Contact blade 46 carries an electrical contact 52 at a distal end thereof, contact blade 48 carries an electrical contact 54 carried at its distal end, while contact blade 50 carries a pair of electrical contacts`56 and 58 at its distal end in line with the other electrical contacts. The switch means are open and closed in accordance with cam - followers 16 and 18 in a manner hereinafter to be described. Cam followers 16 and 18 are pivotally carried on a post 59 to be actuated in accordance with cam 24.
Referring to Figure 2, cam 24 is axially displaced through its ramp means 28 engaging a second ramp means 60 carried by a ring 62.
Ring 62 is coupled to and located by a located means 64 which is fixedly carried on shaft 36. Locator means 64 includes a disk 65 having a stop means 66 in the form of a tab 68 extending from its periphery and a notch 70 through which ring 62 is coupled. Tab 68 engages a boss 72 (Figure 3B~ carried by housing 44 to limit rotation of the disk. Ring 62 is coupled to disk 65 through clutch means 74. Clutch means 74 includes a coil spring 76 carried on a holding means 78. In the present embodiment, holding means 78 includes a boss 80 carried on plate 82 of housing 44 and through which shaft 36 extends. Shaft 36 is held in position by clip 81. An end 84 of the coil spring engages a slot 86 in tab 88 extending from ring 62. Another end 90 of the coil spring is carried in a space 87 between tab 88 and a wall 70' of slot 70 when the tab is inserted in the slot ~See also Figure 3B). Clutch means 74 permits the locator means with the ring 62 to be manually rotated in a predetermined direction to locate the ramp means 60 at a predetermined point and at the same time permits ramp means 60 to engage and move cam 24 axially while the ramp means is held in a fixed position.
Locator means may be manually rotated in either a clockwise or ~551~iO

counterclockwise direction. Ramp means 60 includes a V-shaped tab 92 extending from ring 62 and engaging ramp means 28.
Shaft 36 is manually rotated independently of shaft 34 through a knob (not shown) connected to D-portion 37 of the shaft in a clock-wlse direction. Locator means 64 and ring 62 rotate together through the coupling of spring 76, the spring rotating about boss 80. Rotation is continued to a predetermined position, the rotation being limited by tab 68 engaging boss 72. During power driven rotation of cam 24 in the opposite direction, ramp means 28 engages ramp means 60, ramp means 60 being held in place by a tightening of the spring on boss 80. As will be more fully described hereinafter with reference to Figures 3A
through 6B, during power driven rotation of cam 24, cam followers 16 and 18 ride on the outer most periphery 24' of the cam. When ramp means 28 comes into engagement with ramp means 60, with ramp means 60 being held in place, cam 24 will be axially displaced along shaft 34 to permit cam followers 16 and 18 to sequentially drop and close the contacts of switch means 14. The cam followers will remain in the dropped position until a program cycle is completed at which time a release means 100 permits the cam to be axially displaced past the cam followers to its original position. Release means 100 includes step 26 in cam 24.
Referring to Flgure 7, an alternate form of the invention is presented. In this embodiment, locator means 64 and ring 62 of Figure 2 are of a single integral piece 110. This arrangement, of course, means less parts and makes the device easier to produce. The single piece construction 110 is fixedly carried on shaft 36 and includes rim 112 having a ramp 114 and a stop tab 116 thereon with these elements serving the same function as tab 6~ and ramp 92 of Figure 2.
It has been found that when using the single piece construction, the coil spring 76 of clutch means 74 shown in Figure 2 cannot be used.

1155~60 More specifically, the coil spring in combination with the "play"
between disk 65 and ring 62 of Figure 2 permits the locator means 64 of Figure 2 to be rotated in either a clockwise or counterclockwise direction. With the single piece construction, such play is lost and, -therefore, as is shown in Figure 7, the coil spring has been replaced by clip ring 118 which fits around boss 80' and functionally engages the boss. Clip ring 118 includes tangs 120 and 122 extending from opposite ends of the ring. The larger of the tangs 120 engages slot 124 provided in rim 112 to couple the clip ring to the one piece construction 110.
In operation, the location of ramp 114 can be set by manually rotating shaft 36' to overcome the friction between the clip ring and boss 80' and to thus rotate the one piece construction with the ramp to its desired setting. The position of ramp 114 will then be maintained by the friction between the clip ring and boss 80'.
~ Referring now to Figures 3A through 6B, the operation of the timlng mechanism with partlcular respect to the switch means 14 acting in response to cam 24 can be described. The sequence of operation described assumes that the ramp means 60 has been manually set. Cam 24 may now be continually power driven as long as desired. In Figures 3A and 3B, cam 24 has been axially displaced by permitting cam followers 16 and 18 to engage with step 26 to permit the cam to return at the end of a program. Note that coil spring 40 has expanded to cause the displacement of cam 24. As shown in Figure 3B, in this position all of the electrical contacts of switch means 14 are closed. Thus, the switch means is biased to be normally closed. In Figures 4A and 4B, cam 24 has been rotated an amount sufficient for both cam followers 16 and 18 to disengage step 26 to rise and ride on the outer periphery of the cam 24. As particularly shown in Figure 4B, all of the electrical contacts are now open. The cam followers are made to rise together through the engagement of notch 19 of cam follower 16 engaging tab 17 of cam follower 18. In a microwave oven, the magne~ron would be off.
Note that ramp means 28 and 60 have not been engaged. In Figures 5A
and 5B, cam 24 has been rotated sufficient to cause an initial engage-ment of the two ramp means such that cam follower 16 has dropped off of the outer periphery of the cam. In this position, electrical contacts 54 and 58 are closed and, in the case of the magnetron, power has been applied to the magnetron through a current limiting resistor to cut back the current surge. In Figures 6A and 6B, ramp means 60 and 28 are fully engaged at their peak position to further axially displace cam 24 so that both cam followers 16 and 18 have dropped from the cam's outer periphery to close all of the electrical contacts. Power to the magnetron is now applied through another circuit by-passing the current limiting resistor and remains on until the mode of Figures 4A and 4B
is reached. The complete cycle lasts about 12 seconds, for example.

,,_ -- - , -- . , , . _ _ . . _ . .... _ _.__ . _ . _, . .

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A timing mechanism comprising:
(a) shaft means, (b) integrally constructed first ramp means and locator means for positioning said first ramp means rotatably carried by said shaft means, (c) clutch means comprising a clip ring coupled to said integrally constructed first ramp means and locator means and functionally engaging a boss through which said shaft means extends, (d) a single cam slideably carried on said shaft means and coupling means coupling same to said shaft means for rotation therewith, (e) spring means axially biasing said single cam, (f) second ramp means coupled to said single cam and engaging said first ramp means to selectively axially displace said single cam in a predetermined direction, (g) first and second cam followers engaging said single cam to be sequentially actuated in accordance with an axial displacement of said single cam, and switch means opening and closing in response to said cam followers, and (h) release means permitting said single cam to axially displace past said cam followers to its original position.
2. A timing mechanism according to claim 1 wherein said clip ring includes at least one tang extending therefrom, said tang engaging a slot in said integrally constructed first ramp means and locator means.
CA000379317A 1980-11-10 1981-06-09 Timing mechanism having a short pulse prior to its overall program Expired CA1155160A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/205,737 1980-11-10
US06/205,737 US4348560A (en) 1978-12-11 1980-11-10 Timing mechanism having a short pulse prior to its overall program

Publications (1)

Publication Number Publication Date
CA1155160A true CA1155160A (en) 1983-10-11

Family

ID=22763441

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000379317A Expired CA1155160A (en) 1980-11-10 1981-06-09 Timing mechanism having a short pulse prior to its overall program

Country Status (1)

Country Link
CA (1) CA1155160A (en)

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