United States Patent Bowman et al.
SEQUENTIAL TIMER Inventors: Joe Bowman, Fort Myers Beach, Fla; James D. Edwards, Russiaville,
Assignee: The Scott & Fetzer Company, Kokomo, lnd.
Filed: June 4, 1970 App l. N0.: 43,371
US. Cl. ..74/142, 74/575, 74/568 Int. Cl ..F16h 27/02 Field of Search ..74/142, 143, 568, 575, 142,
References Cited UNITED STATES PATENTS 3,398,591 8/1968 Arko ..74/142 9/1962 Bowman et a1. ..74/568 3,683,711 [451 Aug. 15, 1972 3,090,843 5/ l 963 Hall ..200/38 2,954,662 10/ 1 960 Detwiler ..74/143 2,938,970 5/ l 960 Constantine ..74/5 68 3,239,614 3/1966 Simmons ..200/38 Primary Examiner-William F. ODea 7 Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-Hill, Sherman, Meroni, Gross & Simpson 57] ABSTRACT 20 Claims, 4 Drawing Figures Patented Aug. 15, 1972 INVENTURS J0: flan/MAW Patented Aug. 15, 1972 r 3,683,711
2 Sheets-Sheet 2 1 N VENTORS J05 5 OWMAA/ 1/ JAMas D. [ow 420s BACKGROUND OF THE INVENTION 1. Field of the Invention This invention deals with a sequential timer wherein a main timing cam is moved incrementally at a creep rate.
2. Prior Art Various types of timer constructions have been previously employed to control, by way of example, domestic automatic washing machines. These machines have various types of programs that must be controlled by a sequence timer. For example, a squirrel cage type induction motor is driven in one direction during washing, is then shut off and allowed to coast to a standstill, and is then driven in an opposite direction for effecting spin-drying. The control of such a sequence has entailed the use of a plurality of steps or time-increments on a timer to ensure that the proper sequence is carried out. It is typical for such a motor to coast to a halt in about five seconds, thereby leaving approximately 55seconds of idle time before the next indexing of the timer takes place.
Another example of customary practice in the prior art is that some functions must have a shorter duration than that provided by one step. For instance, if the timer indexes once every minute, that index mechanism can hardly be used to control spray rinses that last but a few seconds each. Thus, it has been common to provide a sub-interval switching mechanism under the control of one of the timer tracks to provide such auxiliary control.
In some programs, there is a need to actuate several switches more or less at the same time, but their sequence must be carefully determined, in order to prevent various kinds of malfunction of control. The example given above is but one, and there are others, and these all have in the past been handled by timerprogram designers by using more than one interval. When a timer interval is used relatively briefly to ensure proper sequence of control, a non-technical user such as a housewife has often been fooled into thinking that a wash cycle has been completed, that the machine has failed or quit for some reason, with various resulting consequences.
Another example where proper switch sequence is needed is where a lid lock is used on a washer which must be unlocked before a second switch shuts off timer power for a deep rinse pause, or else the tub would be inaccessible during such pause. Yet the line control switch must open before a motor interrupter switch closes in order to prevent momentary power being applied to the main motor and thus causing a chugging action.
In a typical commercial timer program, there are 60 uniform teeth of 6 degrees each, or 72 uniform teeth of each. A program of 45 teeth is ordinarily not practicable in this field as more control points are needed.
SUMMARY OF THE INVENTION y In accordance with the present invention, we have eliminated the need for a sub-interval switch, we have eliminated the long control pauses where nothing takes place, and we have enabled three or four functions to be controlled in a predetemiined sequence within one program step, and have done so in an economical manner while using the advantageous features of the sequential timer shown in us. Pat. No. 3,436,975 issued to the same assignee as is this invention. We have achieved the results described by utilizing cam teeth of non-uniform angular size, some teeth being larger than average and some teeth being correspondingly smaller in average without reducing the number of teeth. The larger teeth, when coupled with a creep-step timer, provide adequate time and space for having a number of functions controlled within the angular movement associated with the advancement of one of the larger teeth. At the same time, non-critical functions have been associated with those teeth that are correspondingly smaller.
Accordingly, it is an object of the present invention to provide a sequential timer wherein the motor drives the main timing cam in a step-by-step manner where the magnitude of those steps vary, doing so at a creep rate for each step.
A further object of the present invention is to provide a sequential timer wherein a plurality of switches may be successively controlled within the interval associated with one step or tooth. A still further object of the present invention is to provide a sequential timer wherein sub-interval control functions can be handled by the main timing cam without use of any separate sub-interval switch means.
A further object of the present invention is to provide a sequential timer which can be used to shut off a washing machine motor, to permit such motor to coast to a halt, to reverse the switch phasing thereof and to start it in a reverse direction, doing so all within the interval afforded by one timer tooth or step.
A still further object of the present invention is to provide a sequential timer which enables more events to take place per step and which can shorten any unneeded gaps between events.
Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example.
ON THE DRAWINGS:
FIG. 1 is a side elevational view of a sequential timer, with parts removed for clarity of illustration, and provided in accordance with the principles of the present invention;
FIG. 2 is a fragmentary enlarged diagrammatic view of a portion of the timer of FIG. 1; and
FIGS. 3 and 4 are enlarged views of other timing cams that can be employed in the timer of FIG. 1.
AS SHOWN ON THE DRAWINGS:
The principles of the invention are particularly useful when embodied in a sequential timer of the creepstepping type such as illustrated in FIG. 1, generally indicated by the numeral 10. The timer 10 includes a housing 11 within which is disposed a main timing cam 12, the cam 12 being rotatably supported by the housing 11. The cam 12 is provided with various tracks (FIG. 2) which jointly comprise a program for controlling a plurality of switches that form parts of electric circuits to be controlled by the timer 10. Thus, by the angular position of the timing cam, the various circuits are regulated.
A motor 13 is secured to the housing and has a rotatable output member 14 driven by the motor 13, the output member 14 having a drive portion 15 eccentric to the rotational axis of the output member 14. A drive pawl 16 is carried on the eccentric drive portion is for being continuously reciprocated thereby. The drive pawl 16 is biased about the axis of the drive portion 15 by a spring 17 to urge it into engagement with the timing cam 12. A stoppawl 18 has a pair of ears 19 disposed in recesses in the housing 11 whereby the stop pawl 18 is movably supported, a spring 20 biasing the stop pawl 18 for movement about its support and into engagement with the timing cam 12. A second stop pawl 21 is pivotally supported at 22 by the housing 11 and has an integral spring portion 23 assisted by a further spring 24 which biases the stop pawl 21 into engagement with the timing cam 12.
The timing cam 12, as well as those illustrated in FIGS. 3 and 4 have 60 teeth, and the output member 14 typically makes 1 revolution per minute, whereby in this example, it would take 1 hour to obtain a complete revolution of the timing cam 12. As a practical matter, the cycle may be different in duration and more than one program may appear on the timing cam 12. However, the values are used to illustrate the principles and not in a limiting sense. As there are 60 teeth on the cam 12, the average or mean tooth size corresponds to 6 size.
In accordance with the present invention, certain of the teeth are made larger. When the motor 13 reciprocates the drive pawl 16, the total travel of the drive pawl 16 measured at the teeth of the timing cam 12 corresponds to about 9 of timer can periphery. Thus, the largest tooth that can be accommodated must be less than the travel of the drive pawl 16. With a 9 travel on the drive pawl, an 8 maximum tooth size is thus preferred. Certain 8 teeth have been so designated.
in order to preserve the total number of teeth at 60, for each 8 tooth, it is necessary to compensate by making other teeth smaller. As the travel of the drive pawl 16 is 9 in this example, it would not do to have adjacent teeth as small as 4, because then the drive pawl would pick up two teeth instead of one. Thus, for random tooth locations, it is preferred that each of the teeth of reduced size be greater than half of the travel. As the travel is here 9, half of the travel is 4 and thus the smallest tooth has been made Thus, no two teeth can be picked up at once. Certain of the teeth have been designated as being 5 teeth. Thus, as the drive pawl 16 is reciprocated, successive uniform reciprocations of it efiect incremental angular movements of the timing cam 12 which are of non-uniform angular size. I
The distance between the driving end 25 of the drive pawl 16 and the tooth abutting end face 26 of the stop pawl 18, measured in degrees, is an integral number of 6 teeth. However, when non-uniform teeth are used, this relationship may not exist, and it could be possible for the timing cam 12 to move in a direction opposite to the arrow during the time that it is not driven. The stop pawl 21 is therefore provided at another location,
similarly spacedan integral number of uniform teeth away so that ordinarily one or the other could be expected to engage. Yet, there are times when some tooth arrangements might prevent certainty of intended function, and therefore the tooth abutting end face 27 of the stop pawl 21 is notched as at 28 so as to provide two abutting end face portions which can engage with the drive face portions of the various teeth.
Further, the drive face portion of all of the 8 teeth is also notched, and some of the 6 teeth are correspondingly notched. Further, the notch on some of the 8 teeth is twice as large. The notches mentioned are provided for two purposes. One of these purposes is to simulate an integral number of 6 teeth between the drive pawl and one or both of the stop pawls. Each notch on a 6 tooth and each of the 2 notches on the 8 teeth are provided for that purpose. Where an 8 tooth is provided with a 1 notch, such notch is there to provide clearance to enable the pawls to swing past, but can also be used for compensation purposes.
If one takes the total possible angular movement of the timer cam 12 for a particular cycle, and divides that by the number of teeth that are available for use in that cycle, one obtains the number of degrees per tooth that are available where the teeth are of uniform or average size. For that number of teeth, using the foregoing examples, if one tooth is made larger, then one or more teeth must be made smaller than the uniform size so that the total amount of degrees larger are equal to the total amount of degrees smaller. Thus, according to this invention, there are one or more teeth that are larger than the uniform tooth size used for that cycle.
Having obtained a larger space by use of the larger tooth, than it becomes possible to provide non-random sequencing of three or four switches to control three or four items or groups of items. This result is illustrated in FIG. 2. Here, an 8 tooth is shown as having three cam tracks 30, 31, 32 temiinating within its included angle and respectively associated with switches 33, 34 and 35. The timer can 12 has advanced so that the cam track 30 has closed the switch 33 after about 2 of movement. About 2 later, the track 31 will close the switch 35. Thus, there is approximately a 7-second spacing of all of the actuations with respect to each other and with respect to the ends of travel of that step. The following tooth may be either a 5 or 6 tooth and has a non-critical function to control. Thus, a cam track 36 can control a switch 37 during the following step. According to this teaching, a short cam track can be used to turn one switch both on and off in the same step or off and on in the same step, such as a spray rinse switch, a relay holding circuit or the like. The large tooth thus adds time to the interval that the creep step is taking. Yet, with switches such as 33, 34 and 35, set to be actuated in sequence, entire full increments of stepping can be eliminated from that previously done. For instance, the motor of a wash machine can be stopped at the end of its agitation period, the motor polarity can be reversed in the timer, and the motor can be restarted, all within one step. In the example given, it is customary to dimension the cam tracks 30-32 within one-quarter of a degree of annular movement.
It is preferable that the 5 teeth be immediately adjacent to an 8 tooth so that the customary dial (not shown) associated with the control knob will not various non-uniform teeth arranged in a plurality of groups, while the timer cam 41 in FIG. 4 has all its nonuniform teeth disposed in two adjacent quadrants, those shown in phantom being all uniform. When it is necessary to space two 8 teeth close to each other, they are ordinarily separated by one 5 tooth, and the other compensating 5 tooth is placed as close as practicable, between a pair of 6 teeth.
The examples of tooth pattern shown or described are exemplary as there is no set pattern that must be followed. The important principle to keep in mind is that any two consecutive teeth must have a combined effective size which exceeds the effective travel of the drive pawl 16. Where circumstances permit, non-random tooth arrangements can then be utilized. For instance, with the aforesaid 9 effective travel of the drive pawl, an 8 tooth must be flaked on both sides by teeth between 2 and 8 in size. If compensation is not needed to maintain the number of steps or teeth, or if overcompensation is permissible for increasing the number of teeth, many patterns can be employed. If a 2 or 3 tooth is used, no switch 37 is employed therewith and it merely marks time. A4 tooth can be used to control switch means, but preferably not more than one switch 37. The use of a 4 tooth as compensation for an 8 tooth also simplifies the geometry of stop pawl location where 6 is the mean tooth size. The teeth mentioned herein have sizes which are identified by an integral number of teeth which comprise a factor of 360. This has been done for simplicity of explanation, but fractional intermediate sizes may also be employed. However, the selected examples illustrate to the reader how to tailor his own tooth arrangements using the principles set forth herein.
Although various minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of our contribution to the art.
We claim as our invention:
1. A sequential timer for controlling a number of electric circuits in accordance with a predetermined program, comprising:
a. a housing;
b. a timing cam rotatably supported by said housing, said cam being adapted to control the circuits in response to its angular position;
c. a motor secured to said housing;
d. a rotatable output member driven by said motor and having a drive portion thereon eccentric to the rotational axis of said output member;
e. a drive pawl pivotally carried on said eccentric drive portion for being continuously reciprocated thereby, and biased about the axis of said drive portion;
f. a stop pawl movably supported on said housing and biased for movement about its support; and
g. a series of circularly arranged teeth drivably secured to said timing cam and against which said pawls are biased for respectively rotating said timing cam in one direction and for precluding rotation thereof in the opposite direction, some of said teeth being of non-uniform angular size so that successive uniform reciprocations of said drive pawl effect incremental angular movements of said timing cam of non-uniform angular size.
2. A sequential timer according to claim 1, including a second stop pawl movably supported on said housing and biased for engagement with successive ones of said teeth, said second stop pawl being disposed to preclude timing cam rotation in said opposite direction when the first named stop pawl is out of blocking engagement with said teeth.
3. A sequential timer according to claim 1, in which said stop pawl has a tooth-abutting end face which is notched so as to define two end face portions spaced from each other.
4. A sequential timer according to claim 2, in which one of said stop pawls has a tooth-abutting end face which is notched so as to define two end face portions spaced from each other.
5. A sequential timer according to claim 1, in which at least one of said teeth has a drive face which is notched so as to define two drive face portions spaced from each other.
6. A sequential timer according to claim 1, in which the angular size of one of said teeth exceeds the mean tooth size by an amount that is compensated for by other of said teeth being correspondingly smaller.
7. A sequential timer according to claim 1, in which the angular size of the largest of said teeth is less than twice the angular size of the smallest of said teeth.
8. A sequential timer according to claim 1, including a pluralityof switches successively actuated by a plurality of cam tracks on said cam at spaced time intervals in a'predetermined succession. during the driving of the largest of said teeth by said drive pawl during one of its reciprocations.
9. A sequential timer according to claim 1, in which all said non-uniform angular size teeth are arranged in two adjacent quadrants.
10. A sequential timer according to claim 1, in which said non-uniform angular size teeth are arranged in a plurality of groups spaced from each other by teeth of uniform angular size.
11. A sequential timer according to claim 1, in which the angular size of the largest of said teeth is slightly less than the distance said drive pawl reciprocates, and in which the angular size of the smallest of said teeth is slightly greater than one-half the: distance said drive pawl reciprocates.
12. A sequential timer according to claim 1, including a plurality of cam track steps on said cam at spaced angles for directly producing a plurality of switch actuations in a predetermined succession at spaced time intervals during the driving of the angularly largest of said teeth by said drive pawl during the drive portion of one of its reciprocations.
13. A sequential timer according to claim 1, in which the angular size of two adjacent teeth are unequal, the combined size of said two teeth exceeding the effective travel of said drive pawl.
14. A sequential timer according to claim 1, in which one of said teeth has an angular size larger than onehalf the effective travel of said drive pawl, and smaller than the effective travel of said drive pawl, and a pair of adjacent teeth directly adjacent to said one tooth, each having a size when combined with the size of said one tooth exceeding said effective travel, said one tooth being larger than the average angular size size of said teeth.
15. A sequential timer according to claim 1, in which one of said teeth which is larger than average in angular size is flanked by a pair of teeth which are smaller than average in angular size, said one and said pair of teeth taken together being the angular size of" three average teeth.
16. A sequential timer according to claim 1, in which two of said teeth which are larger than average in angular size are separated by only one smaller-than-average angular size tooth, there being a further smaller-thanaverage angular size tooth disposed elsewhere between a pair of average angular size teeth.
17. A sequential timer according to claim 5, in which said one tooth is larger than average in angular size.
18. A sequential timer according to claim 5, in which said one tooth is average in angular size.
19. A sequential timer according to claim 17, in which at least two of said larger than average angular size teeth have notched drive faces, the notch of one being substantially twice the size of the notch of the other. i
20. A sequential timer according to claim 8 in which said plurality of switches are at least three in number.
UNITED STATES PATENT OFFICE fiERTIFiCATE OF QORRECTION Inventor(s) Ioe Bowman and Iames D. Edwards It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col. 3, line 8 change "is" to 15.
C01. 3, after line 31 insert of cam rotation. Most of the timing cam teeth in this embodiment are of a six-degree C01. 3, line 37 change "timer can" to "timer cam- C01. 4, line 42 change "timer can" to -timer cam- Col. 4, line 45 after "switch" insert --34 and about two degreesla'ter,
the cam track 32 will close the switch-- Signed and sealed this 27th day of November 1973 (SEAL) Attest:
EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attes'ting Officer Acting Commissioner of Patents F M 9 USCOMM-DC seam-ps9 [1.5. GOVERNMENT PRINTING OFFICE: 953 0-366335