U.S. patent number RE29,158 [Application Number 05/548,201] was granted by the patent office on 1977-03-22 for timer blade arrangement.
This patent grant is currently assigned to The Singer Company. Invention is credited to Roger J. Cartier, George Obermann, John Willigman.
United States Patent |
RE29,158 |
Cartier , et al. |
March 22, 1977 |
Timer blade arrangement
Abstract
The timer has switches including upper and lower passive blades
and an active blade therebetween. The distal end of the lower
passive blade has depending spacers which straddle the cam upon
which the follower on the distal end of the active blade rides. The
spacers reference the lower passive blade off the hub of the drum
type program cam. The lower passive blade is provided with a rest
or stop for the upper passive blade limiting downward movement of
that blade. With precision molding, both passive blades are
accurately referenced from the cam hub and the location of the
follower which actuates the active blade is precisely located.
Accuracy of switching is increased without increased precision in
manufacture. Use of two cam tracks permits simultaneous actuation
of the active and "passive" blades to effect faster switching. It
is possible to provide a "make-make" arrangement instead of the
double throw arrangement.
Inventors: |
Cartier; Roger J. (Hoffman
Estates, IL), Obermann; George (Niles, IL), Willigman;
John (Elk Grove Village, IL) |
Assignee: |
The Singer Company (New York,
NY)
|
Family
ID: |
26889774 |
Appl.
No.: |
05/548,201 |
Filed: |
February 10, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
194184 |
Nov 1, 1971 |
03752944 |
Aug 14, 1973 |
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Current U.S.
Class: |
200/38B; 200/283;
200/19.13 |
Current CPC
Class: |
H01H
19/63 (20130101); H01H 43/026 (20130101) |
Current International
Class: |
H01H
43/02 (20060101); H01H 19/00 (20060101); H01H
19/63 (20060101); H01H 43/00 (20060101); H01H
003/42 () |
Field of
Search: |
;200/38B,38BA,38C,38CA,27,153LB,283 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Hohauser; Herman J.
Attorney, Agent or Firm: Michael, Best & Friedrich
Claims
We claim:
1. A timer including a program member rotatable about an axis and
provided with spaced cams,
a switch fixed relative to the program member for actuation by a
cam,
said switch including two blades the free ends of which are biased
towards the program member,
a follower .Iadd.molded .Iaddend.on one of the blades engaging a
cam whereby the cam actuates said one blade relative to the
other,
follower means molded on the second blade engaging the program
member to reference the second blade relative to the program member
.Iadd.and to constrain the second blade against lateral
movement.Iaddend..
2. A timer according to claim 1 in which the switch includes a
third blade biased towards the program member,
said follower means including a stop limiting movement of the third
blade towards the program member.
3. A timer according to claim 2 in which said follower means
engages a separate cam on the program member for actuation
thereby.
4. A timer according to claim 1 in which the switch includes a
third blade,
said follower means including a stop engageable by said third blade
to limit movement of the third blade.
5. A timer according to claim 4 in which the first blade is
actuated by the cam to first engage the third blade and upon
continued motion to move the third blade from said stop into
contact with the second blade.
6. A timer according to claim 4 in which the follower means engages
a separate cam track on the program member whereby the second and
third blades are referenced by the separate cam track while the
first blade is actuated by the first named cam,
said first blade being engageable with either the second or third
blades and the blades moving into or out of contact may be moved in
the desired direction simultaneously to increase the speed of
switching.
7. A timer including a program member provided with spaced cams for
operating switches and means for rotating the program member,
a plurality of switches fixed relative to the program member for
actuation by respective cams,
each of the switches including a blade having its proximal end
fixed and its distal end including a contact and spacer means
.Iadd.molded on the blade and .Iaddend.engaging the program member
so as to reference the contact relative to the program member
.Iadd.and to constrain the blade against lateral
movement.Iaddend.,
a second blade having its proximal end fixed relative to the first
blade with its distal end including a contact and a depending
follower .Iadd.molded on the blade and .Iaddend.engaging one of the
cams on the program member,
the second blade being self-biased to urge the follower into
engagement with the cam whereby the second blade is actuated in
accordance with the configuration of the cam to open and close said
contacts in a programmed sequence.
8. The construction of claim 7 including means confining the
follower on the second blade against lateral movement whereby the
follower is kept on its associated cam.
9. A timer according to claim 7 in which the program member is flat
and said cams are concentric about the center of rotation of the
program member,
said switches being disposed in generally tangential relationship
to the cams.
10. A timer according to claim 7 in which the program member is
cylindrical with the cams axially spaced along the cylinder and the
switches are disposed in generally tangential relationship to the
cylinder.
11. Apparatus according to claim 7 in which said spacer means
engages another cam on the program member whereby both blades may
be actuated by their respective cams.
12. Apparatus according to claim 7 including an electrical barrier
projecting from one of the blades between it and the adjacent
blades of the adjacent switch a sufficient height to electrically
shield the contacts associated with the first switch from the
adjacent contacts.
13. Apparatus according to claim 7 in which the distal end of the
first blade is provided with an upwardly projecting stop,
a third blade having its proximal end fixed relative to the first
and second blades and having its distal end overlying said stop and
having a contact adapted to be engaged by the second blade
contact,
said third blade being self-biased against said stop and movable
upwardly therefrom in response to elevation of the second blade by
the cam to close the second blade contact on the upper blade
contact.
14. A timer according to claim 7 in which the follower on the
second blade is generally disposed on the projected diameter of
said program member.
15. A timer including a program member having spaced cams,
an assembly of spaced switches fixed relative to the program member
for actuation by the cams,
each of said switches including a blade having its free end
self-biased towards said program member and including a spacer
.Iadd.molded on the blade and .Iaddend.acting on the program member
to reference the blade relative thereto,
second blade operatively associated with the first blade in a
switch and having a depending follower .Iadd.molded on the blade
and .Iaddend.biased into contact with the associated cam,
contacts on said blades which are opened and closed according to
the configuration of the associated cam.
16. A timer according to claim 15 in which said spacer is part of
an assembly molded on the end of the first blade, said assembly
including an electrically insulative barrier disposed between the
contacts of said switch and the contacts of an adjacent switch.
17. A timer according to claim 15 in which each said second blade
follower engages its associated cam between means limiting lateral
movement of the follower.
Description
BACKGROUND OF THE INVENTION
In U.S. Pat. No. 3,431,372 there is shown a timer which provided
for a new way of mounting the switches which are actuated by the
timing cam. This arrangement permitted increased accuracy in
switching without any need for adjustment after assembly. In this
arrangement three wafers in which the switch blades are molded are
stacked and any interconnecting between the blades is accomplished
by bussing between the various layers. This construction also
provided for terminating the switch terminals in two groups, both
of which faced the same direction and each of which permitted
plug-in type connectors to be used. The distal ends of the passive
blades were referenced by means of a guide block held between the
end plates of the timer. The guide block also received Teflon
coated steel followers which, by reason of the positioning of the
guide block, where quite accurately located on the projected
diameter of the timing cam. The active blade end projected into the
follower and accurate switching was thus attained.
SUMMARY OF THE INVENTION
The construction of FIGS. 1-5 improves over the patented
construction just described by way of eliminating the guide block
and the separate follower. By molding parts on the ends of the
blades, positive location of the blades with respect to each other
and with respect to the cam is insured. The lower passive blade has
spacers which are referenced relative to the cam hub and thus
accommodate any run-out in the hub shape without adversely
affecting precision of switching. This eliminiates tolerance
problems encountered in the prior construction. The construction
also increases the accuracy of switching without increasing the
precision of manufacture necessary to attain this increased
accuracy. Furthermore, the friction of the follower in the guide
block in the prior construction has been eliminated and, hence, the
torque requirement to turn the cam is reduced to one half.
The construction incorporates integral electrical barriers on the
blade assemblies to minimize the risk of arcing between adjacent
blades. All of this has been attained with cost reduction in
manufacture and in assembly. A further advantage of the increased
accuracy of switching resides in the fact the step (angle of
rotation) for a given size cam drum can be reduced, thus making
more steps available and, hence, more program information possible
or, on the other side, the angular step can be maintained as in the
past but the drum diameter and, hence, size of the overall timer
can be reduced.
The basic construction is readily adapted to "flat" timers as shown
in FIGS. 6 and 7 while retaining the advantages already mentioned.
Further, by providing two cam tracks whereby the "passive" blades
are also actuated as in FIG. 8 the switching time can be made
shorter and permit application to "creep" type timers having flat
cam or drum configuration. The make-make arrangement can readily be
incorporated in any of the foregoing.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows in fragmentary form portions of a timer having a
program cam operating the switches in radially opposed
positions.
FIG. 2 is an end view as indicated in FIG. 1 showing the manner in
which the spacers on the distal end of the blades straddle the cams
operating the switches.
FIG. 3 is similar to a portion of FIG. 1 but illustrates the active
blade in the mid position, that is with no circuit closed.
FIG. 4 is similar to FIG. 3 but shows the active blade closed on
the lower passive blade.
FIG. 5 is an exploded perspective view partly in section further
illustrating the construction.
FIG. 6 is a simplified plan view showing application of the concept
to a flat program cam.
FIG. 7 is a simplified fragmentary view showing the preferred
manner of application to the flat cam in FIG. 6.
FIG. 8 is a simplified view showing a double cam track arrangement
for faster switching time.
FIGS. 9-11 show the concept applied to a make-make switching
arrangement.
DESCRIPTION OF PREFERRED EMBODIMENTS
The program cam drum 10 is located between the timer end plates for
rotation in a counterclockwise direction as viewed in FIG. 1. In
the foreground of FIG. 1 a cam has a maximum elevation portion 12,
a mid portion 14 and a low portion 16. The switch actuated by this
cam has a plastic follower 18 molded on the distal end of active
blade 20, the proximal end of which is embedded in a wafer 22 with
the end of the blade projecting to provide a terminal 24. The
molded wafer 22 is the middle wafer of the three stacked wafers.
The bottom wafer 26 embeds passive blade 28 which has a molded
assembly 30 on its distal end. One portion of this assembly
constitutes a pair of depending spacers 32,32 which ride on the hub
or inter-cam space of the cam drum 10 so as to straddle the cam
12,14,16 against which follower 18 is self-biased. The assembly 30
also includes an electrical barrier 34 projecting upwardly at one
side of the assembly to increase the effective spacing between
adjacent switch assemblies to minimize arcing between adjacent
switches. The assembly 30 also includes a rest or stop 36 which
limits the downward travel of the upper passive blade 38 which is
embedded in the upper wafer 40 with its end also projecting to form
a terminal 42. The lower passive blade also runs through the wafer
to provide a terminal 44.
In the upper portion of FIG. 1 the follower 18 is riding on the
highest portion 12 of the cam so as to lift the active blade and
bring its contact 46 into engagement with the contact 48 carried by
the upper passive blade. The high portion of the cam 12 is selected
so as to lift the distal end of the upper blade 38 off of stop 36
(against its self-bias) to insure good contact pressure. When the
cam is indexed a bit further to the position shown in FIG. 3, the
follower drops down to the mid portion 14 of the cam and at this
point the distal end of the upper blade 38 rests on stop 36 and
contact 46 on the active blade has moved away from contact 48 on
the upper passive blade while contact 50 on the active blade has
not moved down far enough to engage the contact 52 on the lower
blade. Therefore, the circuits are open in this position. A little
further travel of the cam drum to the position shown in FIG. 4 will
allow the active blade to closely approach the low portion 16 in
which position the active blade contact 50 engages contact 52 on
the lower passive blade closing that circuit. Downward movement of
the lower blade is prevented by the spacers and contact pressure is
obtained by the self-bias of the active blade against the lower
blade.
Since the spacers 32 on the molded assembly 30 function to position
the end of the lower blade and also provide the stop for the upper
blade and, hence, determine the minimum spacing between contacts 48
and 52 on the upper and lower blades, respectively, accuracy is
assured in this portion. The molded tip including the follower 18
on the active blade is accurately located and since all of the
wafers are stacked and this locates the root or proximal ends of
the blades, accuracy is insured simply by proper mounting of the
stacked wafers between the timer end plates. Thus it is only
necessary to locate the wafers with some degree of precision and
the follower will then be in the proper location and must be
properly located relative to the passive blades.
It will be noted that the generally diametrically oriented surface
of the follower 18 is on what might be termed the trailing side of
the follower with respect to the direction of rotation of the cam
drum. In the lower portion of FIG. 1 it will be noted that this
condition is still true and, hence, the upper and lower switches
have differently shaped followers relative to the overall assembly.
This is to insure proper tracking on the cam surfaces.
As can be seen in FIGS. 2 and 5, the blades in the upper assembly
(the same is true in the lower assembly) operate on alternate cam
tracks with the opposed assembly of switches on the other side of
the cam drum being operated by the other cams. Since the spacers
reference off the cam hub, any run-out in the cam circumference is
automatically compensated and will not affect switching accuracy.
It will be noted, particularly in FIG. 2, that the spacing between
the spacers and the cam is such that it is not possible to orient
the blades relative to the cam upon which they are to operate in
such a way that the follower would "miss" the cam, that is,...fall
between the cam and an adjacent spacer. The active blade molded
follower and the assembly on the lower passive blade are preferably
self-lubricating plastic such as Nylon or filled Nylon. Due to this
factor and the elimination of the friction of the followers in the
guide blocks as in the aforesaid patent, the torque required to
rotate this assembly is about one half that found in the patent
structure.
In FIG. 5 an additional feature may be noted (it should be noted
that this figure has no particular reference to the others, being
representative only) in that the active blade in the left of the
figure is provided with a laterally projecting arm 54 which
includes a depending finger 56. This permits this blade to operate
or be operated by a lever which is, in turn, operated by a
subinterval cam. For example, this can interconnect a subinterval
cam (old in the art) so as to determine when the subinterval switch
is effective in conjunction with the program cam.
It will be appreciated that not all switches operated by the
program cam need be double acting. Thus in some cases the upper
passive blade can be omitted.
FIGS. 6 and 7 illustrate the adaptation of this concept to a flat
program cam or face cam 60 having radially spaced recessed cam
tracks 62. The switches are positioned in this instance in a
generally tangential relationship to the cam tracks with the
actuation points lying on the radius in the interest of accuracy.
The passive blades are reference relative to the smooth surface 64
between the recessed cam tracks or grooves. Thus the spacer 66
molded on the end of the lower passive blade 68 has a rounded
bottom designed to contact and ride on the smooth inter-cam surface
64. The spacer includes the upwardly projecting finger portion 70
against which the upper passive blade 72 may rest when it is not
being contacted by the active blade 74. The active blade is
provided with a follower 76 which rides in the cam track or groove
62 and in the illustrated position is in the neutral position since
it is riding on surface 78. As the cam moves to the left in FIG. 7
relative to the follower 76, the surface 80 will lift the active
blade into contact with the upper blade 72 which will be lifted
from the rest or finger 70. A little further cam movement will drop
the follower into the deepest portion 82 of the groove 62
permitting the active blade to now contact the lower blade.
In this arrangement as in the first embodiment the switches in any
assembly will operate on alternate cam tracks while the switch
assembly or array on the opposite side of the cam face will be
operated by the other set of alternate cams. Thus in this
arrangement essentially the same construction is provided with the
passive blades referenced from a smooth portion of the program
member. As in the first embodiment, the molded end fitting on the
lower passive blade may include an electrical barrier 84 to
minimize arc over and permit reduction in spacing between adjacent
switches.
The passive blade in the embodiments thus far described is
referenced relative to the smooth surface (i.e. the hub or
intergroove surface) and the active blade is the only blade which
is moved by a cam track. If the program cam is operated in an
intermittent or step-by-step fashion and the actual step is fast,
the switching time will be fast. If it is desired to apply the same
concept to a creep timer or to a stepping timer in which more rapid
switching time is desirable, it is possible to actuate the normally
passive blade along with the active blade. This is illustrated in
FIG. 8 where the active blade 86 has a follower 88 resting on the
cam surface 90. The lower blade 92 has a follower 94 resting in cam
track 96 and including the upwardly projecting finger 100 as well
as the electrical barrier 102. Now, then, it will be apparent by
reference to the drawings that during the next step the lower blade
will be lifted so the follower rests on surface 104 while at the
same time the active blade will drop off surface 90 down to surface
106. Thus the active blade moves down while the heretofore passive
blade 92 moves up. As the blade 92 moves up, the rest 100 also
moves up and the effect is to catch the upper blade 108 on its way
down (following movement) while at the same time allowing the
active blade 86 to drop away from the upper blade, thereby breaking
the circuit rapidly. Increased switching speed can be achieved by
this means to permit application of this construction to a
creep-type timer whether that timer be the flat or face cam type or
the drum type.
In all of the foregoing descriptions the switching action is
essentially SPDT. In some instances it may only be necessary to
have the switch arrangement be SPST (using only two blades). There
are, however, some situations where it would be advantageous to
provide a make-make action in the switching sequence. This can be
provided by the construction shown in FIGS. 9, 10, and 11. Here the
upper blade 110 is provided with an integral molded spacer 112
which has a curved contact or shoe portion riding on the smooth
surface 114 between the cams. The bias of the upper blade 110 will
hold the spacer 112 against the smooth surface 114 but due to the
resiliency of the blade, the blade and its follower can be elevated
when indicated. The free end of the middle blade 116 is biased
against the rest or stop surface 118 on the follower. The lower
blade 120 is self-biased downwardly so that the follower 122 on the
end of the blade will ride in the cam groove as illustrated in
these drawings.
In FIG. 9 the lower blade follower 122 is resting in the bottom
track of the cam groove. There is no contact between the lower
blade and the middle blade and the middle blade cannot contact the
upper blade since both the middle and upper blades are restrained
from further downward movement. When the lower blade follower 122
reaches the surface 124, the lower blade will be lifted into
contact with the middle blade 116 and lift that blade slightly from
the rest 118 so as to insure a good contact pressure. When the
follower 122 is now moved up to rest on the highest cam track
portion 126 the lower two blades move in unison to engage the
middle blade with the top blade with enough overtravel to lift
spacer 112 from the reference surface and thereby obtain proper
contact pressure, this completes the make-make sequence. It will be
obvious that as rotation of the cam continues, the upper pair of
contacts can be opened first followed by opening of the second pair
of contacts or all contacts could be opened substantially at once
by having the follower 122 drop from the highest elevation 126 to
the lowest in one step. While this description has been directed to
application of the make-make circuit to a flat cam, it is obvious
that this will work equally well in connection with a drum-type
program cam.
* * * * *