US3857293A

US3857293A - Timer

Info

Publication number: US3857293A
Application number: US00440595A
Authority: US
Inventors: G Godwin; W Wagle
Original assignee: Sarkes Tarzian Inc
Current assignee: Emerson Electric Co; Sarkes Tarzian Inc
Priority date: 1974-02-07
Filing date: 1974-02-07
Publication date: 1974-12-31
Anticipated expiration: 1991-12-31
Also published as: CA1018573A

Abstract

There is provided a timing device of the type suitable for controlling the cycling of appliances and the like. The timing device employs a known type of switching cam and switch elements. A drive is provided for the switching cam which provides for slow or normal advance of the cam. More specifically, the drive system employs two pawls each of which is advanced independently by means of drive cams. The pawls are provided with short and normal strokes. Each pawl engages separate ratchet teeth in the switching cam. At the time it is desired to have the shorter stroke pawl assume the function of advancing the switching cam, the ratchet teeth for the large advance parl are omitted from the switching cam and this longer stroke pawl then merely moves on the surface of the cam until ratchet teeth are again provided for it to function.

Description

United States Patent [191 Godwin et al.

[ Dec. 31, 1974 TIMER [73] Assignee: Sarkes Tarzian, lnc., Bloomington,

Ind.

[22] Filed: Feb. 7, 1974 [21] Appl. No.: 440,595

[52] US. Cl. 74/118, 74/125, 74/568 T,

74/575, 74/578 [51] Int. Cl..... Fl6h 27/04 [58] Field of Search 74/l 18, 116,568 T, 573,

74/575; 200/38 B, 38 BA, 38 C, 38 CA Wooley 74/l 16 Primary E.\'aminerSamuel Scott Assistant Examiner-F. D. Shoemaker Attorney, Agent, or Firm-Mason, Kolehmaincn. Rathburn & Wyss [57 ABSTRACT There is provided a timing device of the type suitable for controlling the cycling of appliances and the like. The timing device employs a known type of switching cam and switch elements, A drive is provided for the switching cam which provides for slowor normal advance of the cam. More specifically, the drive system employs two pawls each of which is advanced independently by means of drive cams. The pawls are provided with short and normal strokes. Each pawl engages separate ratchet teeth in the switching cam. At the time it is desired to have the shorter stroke pawl assume the function of advancing the switching cam, the ratchet teeth for the large advance pawl are omitted from the switching cam and this longer stroke pawl then merely moves on the surface of the cam until ratchet teeth are again provided for it to func- Hon.

4 Claims, 10 Drawing Figures PATENTEU [R31 1974 3, 857. 293

TIMER The present invention relates to timing devices,and more particularly, to timing devices of the type suitable for controlling the cycling of appliances and the like.

Timing devicesof the type wherein cam means operates a plurality of switches are commonly used to control electrical appliances. Such timing devices generally employ electric drive means to advance cam controlling electrical switches. In modern appliances, the timing device may control a large number of circuits, thus requiring a large number of switches. Moreover, the

' timing devices are commonly used to control different models and different modes of operation of appliances. One such timing device is disclosed and claimed in our copending application, Ser. No. 336,959, filed Mar. 1, 1973 and assigned to the same assignee as the present invention. Frequently, there are no switching operations occurring during certain periods of time, such as when a clothes washer is in a soak cycle or a dishwasher is in a drying cycle. Thus, it may be desirable to drive the control or switching cam at a slower speed during such idle or dwell periods. In this manner, valuable segments of the control cam periphery are preserved for actual switching functions.

Accordingly, it is an object of the present invention to provide a new and improved timing device.

Another object of the present invention is to provide a timing device which overcomes the above mentioned difficulties.

Yet another object of the present invention is to provide a timing device having a slow and a fast advance for the timing control cam.

Yet another object of the present invention is to provide an improved timing device providing greater flexibility of circuitry and switching.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterizethe invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In accordance with these and other objects and advantages,-there is provided an improved timing device which may be used to control the cycling of an electrical appliance and including an improved housing having an axially restrained control cam disc within the housing. The control cam disc is provided with a pair of separate ratchet teeth in its periphery and a drive system is employed with two pawls, each of which is ad-- vanced independently by means of cam means incorporated in a combination cam and gear. The two pawls are arranged with a short stroke and a long stroke and are positioned to engage the separate ratchet teeth in the periphery of the control cam disc. The ratchet teeth engaged by the long stroke pawl, however, are segmented so that at any time it is desired to advance the control cam disc at a slow speed, the large advance pawl merely moves on the surface of the control cam disc until ratchet teeth are again provided for it to function.

Advantageously, the crowded time segments of the control cam disc periphery are preserved for actual switching functions, and the control cam disc is driven at a slower speed during long idle or dwell periods of the electrical appliance.

For a better understanding of the present invention reference may be had to the accompanying drawings wherein:

FIG. 2*is a top view, partly broken away, of the timer of FIG. 1;

FIG. 3 is a front'view, partly in'section, of the timer of FIG. 1;

FIG. 4 is a cross sectional view of the timer of FIG. I, taken along line-44 of FIG. 3;

FIG. 5 is a cross sectional view of the timer of FIG. 1, taken along line 55 of FIG. 4;

FIG. 6 is a fragmentary cross sectional front view of the timer of FIG. 1;

FIG. 7 is a fragmentary cross sectional front view of the timer of FIG. 1;

FIG. 8 is a fragmentary front detailed view of a feature of the timer of FIG. 1;

FIG. 9 is an exploded view of the drive mechanism of the timer of FIG. 1; and

FIG. 10 is an exploded perspective view of the combination cam and gear and pawls of the timer of FIG. 1.

' Referring now to the drawings, there is illustrated a new and improved timer or timing device 10 according to the present invention. The timing device 10 includes a housing 11 formed of a body portion 12 and a top plate 13 enclosing a control cam 15. The control cam 15 is of generally disc-shape having a plurality of circumferential cam tracks 16 formed by the side walls of circumferential grooves or recesses 17. As best illustrated in FIGS. 6 and 7, each of the cam tracks 16 is provided with cam lobes and depressions to provide a desired control sequence. It will be appreciated that, in the illustrated embodiment, cam tracks 16 are defined on opposite sides of the control cam 15; however, the cam tracks 16 and grooves 17 may be limited to one side of the control cam 15 if desired.

To provide for the switching control by the timer 10, there is provided a plurality of switchblades 20, best illustrated in FIG. 3, and each formed of electrically conducting spring material such as spring bronze, provided at one end with a transverse projection defining a cam follower adapted to ride within a respective one of the grooves 17 for engagement along the associated cam track 16. Suitable electrical contacts 21 are provided at the end of the switchblades 20 for breaking electrical circuits.

The other end of the switchblades 20 are supported by a suitable connector block 23, FIG. 1, and secured to suitable terminals 24 in a manner illustrated in our above mentioned copending application.

To provide for manual setting and control of the timer 10, it is provided with a control shaft 25. The control shaft 25 is mounted for axial movement relative to the control cam 15, but is keyed for radial movement or rotation with the control cam 15, as more fully illustrated in our above mentioned copending application. The control shaft 25 is axially movable from a first or of position to a second or on" position and to this end, the control shaft is provided with a hair pin spring 26, FIG. 3, which rides in a pair of detents on the control shaft 25 and provides snap acting and detenting or locking of the control shaft 25 into one of the axial positions.

Suitable means must be provided for driving or rotating the control cam 15, and to this end, there is provided a first drive assembly according to the present invention and generally illustrated at 30. The drive assembly includes an electric drive motor 31 having a drive pinion 32 secured to its drive shaft 33. The drive pinion 32 operatively engages a combination cam and gear 35. Specifically, the combination cam and gear includes a gear portion 36 having drive teeth in its periphery operatively engaged by the pinion 32, and further includes integrally therewith, a pair of drive earns 37, 38, best illustrated in FIG. 10. In addition, the underside of the combination cam and gear 35, as viewed in FIG. 10, may include additional cam means 39, FIG. 8. Operatively associated with a combination cam and gear is a long stroke pawl and a short stroke pawl 41. The long stroke pawl 40 includes a yoke-type cam track 40A in which thedrive cam 37 rides, and the short stroke pawl 41'includes a yoke-type cam track 41A in which the drive cam 38 rides. Thus, each rotation of the combination cam and gear is effective to stroke. The long stroke pawl 40, due to the configuration of its cam track 40A and associated drive cam 37 will, however, have a substantially longer stroke than the short strokepawl 41. The combination cam and gear 35 rides on an idle shaft and the

pawls

40, 41 are held assembled therewith by a spring washer 46 and C-ring 47, FIGS. 3 and 9.

The control cam 15 is provided with two sets of ratchet tracks 43, 44 in' its periphery, FIGS. 6 and 7. In the illustrated embodiment, the ratchet track 44 is provided with ratchet teeth 44A continuously around the control cam 15 while the ratchet track 43 is segmented with ratchet teeth 43A and smooth peripheral portions 438 which are void of ratchet teeth. Each of the

pawls

40 and 41 includes a

pawl portion

40B, 41B adapted to ride along a respective one of the ratchet tracks 43, 44 and biased into engagement therewith. In a preferred embodiment, the

pawls

40, 41 are formed of plastic or other suitable resilient material and are biased toward the ratchet tracks 43, 44 by suitable springs 40C, 41C molded integrally with the remainder of the

pawls

40, 41.

The pitch of the ratchet teeth 43A for engagement by the tip 408 of the long stroke pawl 40 are an even multiple of the pitch of the smaller ratchet teeth 44A so that the pawl 40 with the longer stroke will advance the control cam 15 a multiple of the angular advance of the short stroke pawl 41. In one embodiment of the invention, each stroke of the short stroke pawl 41 advances the control cam 15 two degrees; each stroke of the long stroke pawl 40 advances the cnontro] cam 15 six degrees when the pawl portion 408 thereof engages a ratchet tooth 43A. However, since the ratchet track 43 is segmented so that a portion of the periphery thereof is smooth, as at 438, the pawl 40 will ride over this smooth area on the surface of the ratchet track until the ratchet teeth 43A areagain provided for it to function. During this time, the slow advance pawl 41 assumes the function of advancing the control cam 15.

An anti-back pawl is provided to function on the slow advance ratchet teeth 44A which are continuous around the periphery of the control cam 15.

The cam means 39 on the underside of the combination cam and gear 35 provide for a sub-interval switchng means, and in the illustrated embodiment,

provides two sub-interval switching functions by means of a pair of

contact blades

51, 52 and a common spring blade 53, FIG. 8. The sub-interval switching functions can take many desired modes. It will be seen that the sub-interval functions are directly related to the switching functions of the control cam 15.

The timer 10 may also be provided with an additional drive means 55 so that the control cam 15 may be advanced at a comparatively rapid rate by a separate motor and drive train, with this action controlled by the switching and the timer itself. Thus, the drive means 55 in the illustrated embodiment, includes an electric drive motor 56 and drive train assembly 57. The drive train assembly 57 may be of any suitable type, and may be of the type more fully illustrated and described in US. Pat. No. 3,335,235, Aug. 8, 1967 to G. A. God win. The drive train assembly 57 includes a final drive gear 58 meshing with a ring gear 59 defined in the periphery of the control cam 15 intermediate the ratchet tracks 43, 44. As more fully described in the above mentioned patent, the final drive gear is supported on a gear plate 60 pivotally mounted at 61. Thus, the electric drive motor 56, when energized, will drive the control cam 15 in a counterclockwise position as viewed in FIGS. 6 and 7. Moreover, it will be understood from the earlier patent that rotation of the control cam 15 through the control shaft 25 or by action of the

drive pawls

40 or 41 will be effected to ratchet the final drive gear 58 out of engagement with the ring gear 59 and permit unrestricted advance of the control cam 15. Moreover, the electric drive motor 56 may be driven intermittently, controlled by switching in the timer itself.

Although the present invention has been described by reference to a single embodiment thereof, it will be apparent that numerous other modifications and embodiments may be devised by those skilled in the art and it is intended by the appended claims to cover all such modifications and embodiments which will fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A multispeed drive mechanism for a timing device and the like comprising:

a control cam for connection to a timer shaft;

a first ratchet track in the periphery of said control cam having ratchet teeth for slow speed roation of said control cam;

a second ratchet track in the periphery of said control cam being segmented to provide ratchet teeth and smooth areas and having a pitch of a multiple of the pitch of the first set of ratchet teeth;

first and second pawls operatively associated respectively with said first and second sets of ratchet teeth;and

pawl drive means operatively associated with the first and second pawls to advance and retract said pawls synchronously, each through a stroke a distance equal the pitch of its associated ratchet teeth.

2. A drive mechanism as set forth in claim 1 wherein each of said pawls is provided with a yoke follower and said pawl drive means includes a continuously driven combination cam and gear including a short stroke cam and a long stroke cam received respectively within the yoke followers of said pawls.

6 3. A drive mechanism asset forth in claim 1 wherein 4. A drive mechanism as set forth in claim 1 wherein said control cam is additionally provided with gear each of said pawls if formed of resilient material and teeth in its periphery, and further including an addiincludes an integrally formed spring biasing the pawl tional drive means having a final drive gear operatively into engagement with its respective ratchet teeth. associated with the gear teeth of said control cam. 5

Claims

1. A multispeed drive mechanism for a timing device and the like comprising: a control cam for connection to a timer shaft; a first ratchet track in the periphery of said control cam having ratchet teeth for slow speed roation of said control cam; a second ratchet track in the periphery of said control cam being segmented to provide ratchet teeth and smooth areas and having a pitch of a multiple of the pitch of the first set of ratchet teeth; first and second pawls operatively associated respectively with said first and second sets of ratchet teeth;and pawl drive means operatively associated with the first and second pawls to advance and retract said pawls synchronously, each through a stroke a distance equal the pitch of its associated ratchet teeth.

3. A drive mechanism as set forth in claim 1 wherein said control cam is additionally provided with gear teeth in its periphery, and further including an additional drive means having a final drive gear operatively associated with the gear teeth of said control cam.

4. A drive mechanism as set forth in claim 1 wherein each of said pawls if formed of resilient material and includes an integrally formed spring biasing the pawl into engagement with its respective ratchet teeth.