US3724248A

US3724248A - Timer

Info

Publication number: US3724248A
Application number: US00187416A
Authority: US
Inventors: G Obermann
Original assignee: Controls Company of America
Current assignee: Eaton Corp
Priority date: 1971-10-07
Filing date: 1971-10-07
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03
Also published as: DE2246985A1; IT968580B; CA948246A; JPS4845789A; FR2156076A1; FR2156076B3

Abstract

The outer ratchet wheel is a part of the timing cam drum of a step-by-step type of interval timer. The outer ratchet is advanced by means of a pawl which is reciprocated as the slow rise fast drop cam rotates to retract the pawl one tooth and advance the pawl with a snap action until the pawl abuts a stop member, at which time the retaining pawl engages the same tooth to hold the cam in place. At certain intervals or positions on the outer ratchet the teeth are missing thereby allowing the drive pawl (and then the retaining pawl) to ''''reach inside'''' and engage a time delay ratchet which is then advanced inside the outer ratchet a number of steps until the inner ratchet engages the inside of the outer ratchet and starts driving the outer ratchet until the drive pawl and retaining pawl are back onto the outside ratchet, at which time the inside ratchet is released and returned to its original point by the spring bias. This allows what would normally be a short interval on the outer ratchet to be ''''stretched'''' to provide a long interval without consuming too many steps of the timing cam.

Description

Waited States aterrt [1 1 @bermann [54] TIMER [75] Inventor:

[73] Assignee:

George Obermann, Niles, lll.

Controls Company of America, Mel- 51 Apr. 3, 1973 Primary ExaminerCharles J. Myhre Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-John N. Michael et al.

[57] ABSTRACT The outer ratchet wheel is :1 part of the timing cam drum of a step-by-step type of interval timer. The outer ratchet is advanced by means of a pawl which is reciprocated as the slow rise fast drop cam rotates to retract the pawl one tooth and advance the pawl with a snap action until the pawl abuts a stop member, at which time the retaining pawl engages the same tooth to hold the cam in place. At certain intervals or positions on the outer ratchet the teeth are missing thereby allowing the drive pawl (and then the retaining pawl) to reach inside and engage a time delay ratchet which is then advanced inside the outer ratchet a number of steps until the inner ratchet engages the inside of the outer ratchet and starts driving the outer ratchet until the drive pawl and retaining pawl are back onto the outside ratchet, at which time the inside ratchet is released and returned to its original point by the spring bias. This allows what would normally be a short interval on the outer ratchet to be stretched to provide a long interval without consuming too many steps of the timing cam.

3 Claims, 4 Drawing Figures TIMER CROSS-REFERENCE TO RELATED APPLICATION The specific drive mechanism here, i.e. without the interval stretching feature of this invention, is shown and claimed in U.S. Pat. No. 3,395,585.

BACKGROUND OF THE INVENTION Washing machine timers are classically advanced in a step-by-step manner at timed intervals. Generally the angular step of the timing cam is 7.2 (50 steps for a total revolution) or in some cases 6 (60 steps), which represents about the practical minimum for proper operation of the timer. Thus, only 50 or 60 steps are available in a complete revolution of the timing cam and obviously only one revolution is available since the programs then begin to repeat.

There is an increasing demand for various programs for different washing programs. Thus there is a squeeze on the designer to provide more programs within the 360 rotation of the timing cam. Coupled with this desire there is a desire to provide for long soak periods and the like which normally consume a considerable number of steps in the timing advance sequence. Therefore, it is desirable to provide some way of providing long intervals while still being able to provide a number of programs on the timing cam.

SUMMARY OF THE INVENTION This invention is directed to provision of apparatus which permits stretching of selected intervals so as to considerably increase the effectiveness of the timer. Thus a desirable number of programs can still be provided on the timing cam, desirable step increments can be retained i.e. 6 or 7.2) and still the selected intervals can be substantially increased. The construction described in the Abstract, in effect, allows the timing cam to be parked while the stretched interval occurs. At the conclusion of the stretched interval the advance mechanism once again starts driving the timing cam. This arrangement can be provided without greatly increasing the cost of the timer.

DESCRIPTION OF THE DRAWING FIG. 1 is a bottom plan view of the escape mechanism taken on meandering line as shown in FIG. 2.

FIG. 2 is a fragmentary vertical section with parts broken away showing the orientation of the stepping ratchet and time lapse ratched to the timing cam.

FIG. 3 is a fragmentary view showing the manner in which the drive mechanism can actuate the time lapse ratchet while the stepping ratchet remains stationary.

FIG. 4 is a view comparable to FIG. 3 but shows a position of the parts after the drive mechanism has returned to the stepping ratchet and the time lapse ratchet is in process of returning to its starting point.

DESCRIPTION OF PREFERRED EMBODIMENT the drive pawl 14 mounted on pivot 16 carried by lever 18 which is journaled on the same axis as the timing cam. The free end of the lever 18 is actuated by a slow rise fast drop cam 20 which will gradually depress the lever (as seen in FIG. 1) to move the pawl back a tooth and when the end of the lever reaches the drop face of the cam the lever rapidly drops to the low point on the cam and drives the pawl forward to advance the stepping ratchet 12 and the associated timing cam forward one step. Lever 18 is spring biased in a counterclockwise direction as viewed in FIG. 1. The biasing spring is not shown since such arrangements are known in the art. The length of the drive step is determined by engagement of the end of drive pawl 14 with the stop member 22 pivoted on pivot 24 and underlying the I holding pawl 26. During the advance stroke, the holding pawl is cammed out of engagement with the ratchet but as soon as the stroke is completed the large tooth on the end of the holding pawl drops into the adjacent space between the ratchet teeth to retain the ratchet in position. Both the holding pawl 26 and the drive pawl 14 are biased into engagement with the ratchet teeth by a single spring 28. The drive mechanism thus far described is that shown in the aforesaid patent.

As may be seen in FIGS. 1 and 2, teeth are missing at the various locations around the periphery of the stepping ratchet. Thus teeth are missing at 30, 32, 34, 36, 38 and 40. These gaps correspond to positions of the timing cam at which a long interval is desired.

Interval ratchet 42 is rotatably mounted on the hub 44 of the timing cam drum harbor so that it can rotate relative to the timing cam drum. The spring 46 coiled around the shaft portion 48 of the inside ratchet member is connected to the ratchet member at 50 and is connected to the timing cam arbor at 52 so that the ratchet is biased in a clockwise direction (FIG. 1) to position the tooth 54 in abuting relation to the radially inwardly projecting face or portion of 56 of the outer ratchet. The rotatable mounting of the inner ratchet wheel relative to the outer ratchet will permit the inside ratchet wheel to be moved relative to the outer ratchet wheel until the lug 58 on the inner ratchet hits face 60 on the inwardly projecting portion of the outer ratchet at which time any further effort to move the inner ratchet would force the outer ratchet to move with the inner ratchet. Now then, as pointed out above, the various gaps in the outer ratchet correspond with positions in the program timing cam at which a long interval is desired. It should be borne in mind that the entire program timing cam may actually provide for a number of programs. In FIG. 1 the advancing pawl 14 has moved the outer ratchet to a position immediately adjacent the gap 36 at which time an interval would be desired. When the pawl next advances it will drop into the hold and hit the flat tooth 62 on the inner ratchet. The antireverse pawl 26 will also land here and will restrain the outer ratchet. On the next step the ratchet will slide the advance pawl back along the flat tooth 62 until it lands inthe adjacent notch in the inner ratchet and then the advance stroke will move the inside ratchet relative to the outside ratchet whereupon the anti-reverse pawl will engage the inner ratchet to hold it in its advanced position against the bias of the return spring 46. The auxiliary anti-reverse pawl 64 holds the outer ratchet. During this step it is obvious that no movement of the outer ratchet occurred and hence the timing cam remains stationary. Thus it is now necessary to advance the inner ratchet relative to the outer ratchet until such time as the lug 58 engages face 60 to pick up the outer ratchet and transfer advance motion to the outer ratchet and hence the timing cam. This will, of course, force the advance pawl and the anti-reverse pawl to rise up and start operating on the stepping ratchet. Upon release of the inner ratchet, the return spring 46 returns it to its starting point so that the full stretched interval will be available when next the timer is advanced to a position where along interval is desired. As shown, that next position would be adjacent tooth 66 and the next movement of the advance pawl would drop down into notch 68 on the inner ratchet.

Since the nature of the advance mechanism per se is such as to permit variable steps it is possible to vary the interval or provide different intervals at different cutouts in the outer ratchet simply by varying the tooth spacing of the inner ratchet portion which will be effective for the stretched interval. Thus the number of steps in effect can be decreased for a given stretched interval and therefore not all stretched intervals need be the same. The versatility afforded by this arrangement in programming the timer greatly increases the mount of programming which can be effected by a timer without unduly increasing the diameter of the drum and hence the size of the timer.

FIG. 3 shows the position of the advance mechanism while it is driving the inside ratchet relative to the outside ratchet. This also illustrates the manner in which the holding pawl operates on both ratchets during the stretched interval phase of operation. FIG. 4 illustrates the position in parts after the mechanism has returned to the outer ratchet and (with some artistic license) the inner ratchet is shown in the process of returning to its zero point.

I claim:

1. A program timer of the type advanced in a stepby-step manner to sequentially actuate switches in accordance with the rotational position of the program cam, comprising,

a ratchet wheel having spaced teeth,

a stepping mechanism including an advance pawl engageable with the ratchet wheel to advance the ratchet wheel in a step-by-step manner to sequential positions determining the position of the program timing cam, some of the teeth of the ratchet being omitted in at least one position on the periphery of the ratchet so as to leave a gap through which the advancing pawl may project inwardly, second ratchet wheel positioned inside the first with teeth underlying the gap in the outer ratchet wheel whereby the advancing pawl will operate through the said gap onto the inner ratchet wheel and advance it in a step-bystep manner,

said inner ratchet wheel being biased to an initial position and being rotatably relative to the outer ratchet wheel to a second position in which the inner and outer ratchet wheels become engaged and move in unison whereby the timing cam remains stationary during such period as the advancing pawl is advancing the inner ratchet relative to the outer ratchet and upon the two ratchets becoming interengaged the advance pawl returns to the outer ratchet and is disengaged from thejnner ratchet which then returns 0 its initial position under influence of its sprm g bias.

2. A timer according to claim 1 including holding means operative to engage said outer ratchet during each back step movement of the advancing pawl and thereby prevent movement of the program timing cam in the interval between the advancing steps,

second holding means operative on said inner ratchet wheel to retain it in its advanced position relative to the outer ratchet 'wheel during the interval between advancing steps imparted to the inner ratchet wheel.

3. Apparatus according to claim 2 in which the holding means for both ratchet wheels are carried by the same member and comprises holding pawls,

one of said holding pawls engaging the outer ratchet until it reaches said gap and thereupon engaging the inner ratchet,

the other holding pawl being an auxiliary pawl which engages the outer ratchet while the first holding pawl engages the inner ratchet.

Claims

1. A program timer of the type advanced in a step-by-step manner to sequentially actuate switches in accordance with the rotational position of the program cam, comprising, a ratchet wheel having spaced teeth, a stepping mechanism including an advance pawl engageable with the ratchet wheel to advance the ratchet wheel in a step-bystep manner to sequential positions determining the position of the program timing cam, some of the teeth of the ratchet being omitted in at least one position on the periphery of the ratchet so as to leave a gap through which the advancing pawl may project inwardly, a second ratchet wheel positioned inside the first with teeth underlying the gap in the outer ratchet wheel whereby the advancing pawl will operate through the said gap onto the inner ratchet wheel and advance it in a step-by-step manner, said inner ratchet wheel being biased to an initial position and being rotatably relative to the outer ratchet wheel to a second position in which the inner and outer ratchet wheels become engaged and move in unison whereby the timing cam remains stationary during such period as the advancing pawl is advancing the inner ratchet relative to the outer ratchet and upon the two ratchets becoming interengaged the advance pawl returns to the outer ratchet and is disengaged from the inner ratchet which then returns to its initial position under influence of its spring bias.

2. A timer according to claim 1 including holding means operative to engage said outer ratchet during each back step movement of the advancing pawl and thereby prevent movement of the program timing cam in the interval between the advancing steps, second holding means operative on said inner ratchet wheel to retain it in its advanced position relative to the outer ratchet wheel during the interval between advancing steps imparted to the inner ratchet wheel.

3. Apparatus according to claim 2 in which the holding means for both ratchet wheels are carried by the same member and comprises holding pawls, one of said holding pawls engaging the outer ratchet until it reaches said gap and thereupon engaging the inner ratchet, the other holding pawl being an auxiliary pawl which engages the outer ratchet while the first holding pawl engages the inner ratchet.