Related Applications
[0001] This application claims the benefit of and priority to U.S. Patent
Application Serial Number 13/923,653, filed June 21, 2013, the contents of which are
hereby incorporated by reference as if recited in full herein.
Field of the Invention
[0002] The present invention relates to shaft assemblies particularly suitable for
circuit breakers.
Background of the Invention
[0003] Circuit breakers are one of a variety of overcurrent protection devices used
for circuit protection and isolation. The circuit breaker provides electrical protection
whenever an electric abnormality occurs. In a circuit breaker, current enters the system
from a power line and passes through a line conductor to a stationary contact fixed on the
line conductor, then to a movable contact. The movable contact can be fixedly attached
to a pivoting arm. As long as the stationary and movable contacts are in physical contact, •
current passes from the stationary contact to the movable contact and out of the circuit
breaker to down line electrical devices.
[0004] In the event of an overcurrent condition (e.g., a short circuit), extremely
high electromagnetic forces can be generated. The electromagnetic forces repel the
movable contact away from the stationary contact. As shown by an example of a prior
art circuit breaker in Figure 1, the circuit breaker 10 includes a stationary contact 30, a
moveable arm 35, and a mechanism assembly 10m with a cam assembly 100 that
includes a "C" that communicates with a cam follower 50. Because the movable contact
35c is fixedly attached to the rotating arm 35, the arm 35 pivots and physically separates
the stationary 30 and movable contacts 35c, thus tripping the circuit. Upon separation of
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the contacts and blowing open the circuit, an arcing condition occurs. The breaker's tripunit
will trip the breaker which will cause the contacts to separate.
[00051 Figures 2A and 2B illustrate an example of the mechanism assembly 10m
with the cam assembly 100. Conventionally, the cam assembly 100 holds the
components on the shaft 101 via rivets.
Summary of Embodiments of the Invention
[0006] Embodiments of the present invention are directed to circuit breakers with
cam assemblies that include self-locking retaining rings that cooperate with a shaft.
[0007] Embodiments of the invention are directed to cam assemblies for circuit
breakers. The cam assemblies include: (a) a shaft comprising at least one notch; (b) a
cam held on the shaft; and (c) at least one self-retaining locking ring that engages a
respective one of the at least one notch to lock the cam in position on the shaft.
[0008] The cam assembly may also include a hub held on the shaft longitudinally
spaced apart from the at least one notch. The cam can be locked in an axial position on
the shaft between the hub and locking ring.
[0009] The at least one notch can be a plurality of closely spaced
circumferential!y extending notches with centerlines of adjacent notches spaced between
about 0.001 inches to about 0.020 inches apart.
[0010] The cam can include a plurality of cooperating components that are held in
abutting contact on the shaft using the at least one locking ring.
[0011] The cam assembly can be in combination with a circuit breaker having a
housing with the cam assembly held inside the housing. The shaft and cam can be nonferromagnetic
cast metal or metal alloy components.
[0012] The at least one notch can include at least one circumferentially extending
notch that is discontinuous about a perimeter of the shaft with opposing perimeter
portions of a respective notch being separated by at least one flat segment.
[0013] The at least one notch can be a plurality of spaced apart circumferentially
extending notches with wall segments having a greater outer diameter residing
therebetween. The notches can have a substantially constant width that is between about
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0.010 inches to about 0.020 inches, on average, and a depth that is between about 0.001
inches to about 0.010 inches, on average.
[0014] The at least one notch can be a plurality of notches with a depth of about
0.005 inches, average, and a substantially constant width (in an axial direction) that is
between about 0.010 inches and about 0.015 inches, average.
[0015] The at least one notch can be a plurality of spaced apart circumferential ly
extending notches with a respective substantially constant width and with wall segments
having a greater outer diameter than a diameter or diameters of the notches residing
therebetween.
[0016] The wall segments can have a respective width that is less than the width
of the notches.
[0017] The wall segments can have a respective width that is the same as the
width of the notches.
[0018] The wall segments can have a respective width that is greater than the
width of the notches.
[0019] The at least one locking ring can engage the shaft to define an axial pull
off force that is between about 100 lbf to about 1000 lbf.
[0020] Other embodiments are directed to a mechanism assembly for circuit
breaker. The assembly includes a cam assembly and a rotating contact arm in
communication with the cam assembly. The cam assembly includes a shaft with at least
one notch; a cam held on the shaft; and at least one self-retaining locking ring that
engages a respective one of the at least one notch to lock the cam in position on the shaft.
[0021] The at least one notch can be a plurality of closely spaced
circumferential ly extending notches with centerlines of adjacent notches spaced between
about 0.001 inches to about 0.020 inches apart.
[0022] The cam can include a plurality of cooperating components that are held in
abutting contact at a defined axial location on the shaft using the at least one locking ring.
[0023] The shaft and cam can be non-ferromagnetic cast metal or metal alloy
components.
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[0024] The at least one notch can include a plurality of notches that are
discontinuous in a circumferential direction with opposing perimeter portions separated
by at least one flat segment.
[0025] The at least one notch can be a plurality of spaced apart notches with wall
segments having a greater outer diameter than an outer diameter of the notches residing
therebetween. The notches can have a width that is between about 0.010 inches to about
0.020 inches, on average, and a depth that is between about 0.001 inches to about 0.010
inches, on average.
[0026] Still other embodiments are directed to a shaft assembly. The shaft
assembly includes an elongate shaft having a plurality of closely spaced apart
circumferentially extending external notches with wall segments having a greater outer
diameter than an outer diameter of the notches residing therebetween. The notches can
have a width that is between about 0.010 inches to about 0.020 inches, on average, and a
depth that is between about 0.001 inches to about 0.010 inches, on average. The
assemblies can include at least one self-retaining locking ring that engages one of the
notches to axially lock into position on the shaft and provide a pull out force that is
between about 100 lbf to about 1000 lbf.
[0027] The at least one notch can be a plurality of notches with a depth of about
0.005 inches, average, and a width between about 0.010 inches and about 0.015 inches,
average.
[0028] Further features, advantages and details of the present invention will be
appreciated by those of ordinary skill in the art from a reading of the figures and the
detailed description of the preferred embodiments that follow, such description being
merely illustrative of the present invention.
[0029] It is noted that aspects of the invention described with respect to one
embodiment, may be incorporated in a different embodiment although not specifically
described relative thereto. That is, all embodiments and/or features of any embodiment
can be combined in any way and/or combination. Applicant reserves the right to change
any originally filed claim or file any new claim accordingly, including the right to be able
to amend any originally filed claim to depend from and/or incorporate any feature of any
other claim although not originally claimed in that manner. These and other objects
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and/or aspects of the present invention are explained in detail in the specification set forth
below.
Brief Description of the Drawings
[0030] Figure 1 is a side partial cutaway view of an exemplary prior art circuit
breaker.
[0031] Figure 2A is a front, side partial cutaway perspective view of a prior art
mechanism assembly used in a circuit breaker.
[0032] Figure 2B is a rear perspective view of a mechanism assembly.
[0033] Figure 3 is an enlarged partial side perspective view of a cam assembly
according to embodiments of the present invention.
[0034] Figure 4 is an end view of the cam assembly shown in Figure 3 according
to embodiments of the present invention.
[0035] Figure 5 is a side perspective view of the cam assembly shown in Figure
4.
[0036] Figure 6 is an exploded view of the cam assembly shown in Figure 3.
[0037] Figure 7 is a side view of the cam assembly shown in Figure 3.
[0038] Figure 8A is an enlarged view of a portion of a cam shaft suitable for use
in the cam assembly of Figure 3 according to embodiments of the present invention.
[0039] Figure 8B is a table of exemplary dimensions and associated axial pull off
forces (pounds) according to embodiments of the present invention.
[0040] Figure 9 is an exemplary circuit breaker that can include the cam
assembly shown in Figure 3 according to some embodiments of the present invention.
Detailed Description of Embodiments of the Invention
[0041] The present invention now will be described more fully hereinafter with
reference to the accompanying drawings, in which illustrative embodiments of the
invention are shown. Like numbers refer to like elements and different embodiments of
like elements can be designated using a different number of superscript indicator
apostrophes (e.g., 40,40', 40", 40'").
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[0042] In the drawings, the relative sizes of regions or features may be
exaggerated for clarity. This invention may, however, be embodied in many different
forms and should not be construed as limited to the embodiments set forth herein; rather,
these embodiments are provided so that this disclosure will be thorough and complete,
and will fully convey the scope of the invention to those skilled in the art.
[0043] It will be understood that, although the terms first, second, etc, may be
used herein to describe various elements, components, regions, layers and/or sections,
these elements, components, regions, layers and/or sections should not be limited by
these terms. These terms are only used to distinguish one element, component, region,
layer or section from another region, layer or section. Thus, a first element, component,
region, layer or section discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of the present invention.
[0044] Spatially relative terms, such as "beneath", "below", "lower", "above",
"upper" and the~Iike, may be used herein for ease of description to describe one element
or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It
will be understood that the spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over, elements described as
"below" or "beneath" other elements or features would then be oriented "above" the other
elements or features. Thus, the exemplary term "below" can encompass both an
orientation of above and below. The device may be otherwise oriented (rotated 90° or at
other orientations) and the spatially relative descriptors used herein interpreted
accordingly.
[0045] The term "about" refers to numbers in a range of +/-20% of the noted
value.
[0046] As used herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless expressly stated otherwise. It will be further
understood that the terms "includes," "comprises," "including" and/or "comprising,"
when used in this specification, specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the presence or addition of
one or more other features, integers, steps, operations, elements, components, and/or
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groups thereof. It will be understood that when an element is referred to as being
"connected" or "coupled" to another element, it can be directly connected or coupled to
the other element or intervening elements may be present. As used herein, the term
"and/or" includes any and all combinations of one or more of the associated listed items.
[0047] The term "non-ferromagnetic" means that the noted component is
substantially free of ferromagnetic materials so as to be suitable for use in the arc
chamber (non-disruptive to the magnetic circuit) as will be known to those of skill in the
art.
[0048] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of ordinary
skill in the art to which this invention belongs. It will be further understood that terms,
such as those defined in commonly used dictionaries, should be interpreted as having a
meaning that is consistent with their meaning in the context of this specification and the
relevant art and will not be interpreted in an idealized or overly formal sense unless
expressly so defined herein.
[0049] The term "self-retaining" with respect to a locking ring means that the
locking ring engages a shaft to lock into axial position and requires no other component.
[0050] Turning now to the figures, Figure 1 illustrates a circuit breaker 10 with a
housing lOh. As is well known, in the housing lOh, the circuit breaker 10 includes at
least one arc chamber 11 having an arc chute 25 with arc plates, a mechanism assembly
10m with a rotating arm 35 with a contact 35c (e.g., a "contact arm") and a line conductor
assembly comprising a stationary contact 30. The arc plates can be stacked and are
typically configured as closely spaced plates as shown.
[0051] The circuit breaker 10 also includes a cam assembly 100 with a cam C.
The cam assembly 100 is typically part of the mechanism assembly 10m as shown in
Figures 2A and 2B.
[0052] Referring again to Figure 1, the circuit breaker 10 also includes a cam
follower 50 that cooperates with the cam C and may optionally include a crossbar 60.
The cam follower 50 can reside in a channel of the crossbar over a spring 62 or other
biasing member, allowing the cam follower 50 to travel up and down a distance while a
lower post 53 is retained in the channel. However, it is noted that the invention is not
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limited to this circuit breaker configuration and other cam and cam follower
configurations may be used.
[0053] The cam C and cam follower 50 can comprise non-ferromagnetic
electrically conductive material.
[0054] Conventionally, as shown in Figures 2A and 2B, the circuit breaker 10
has a housing lOh and mechanism assembly 10m had a cam assembly 100 that was
assembled using rivets. The housing lOh can have a front lOf and an interior
compartment for holding the mechanism assembly 10m. The riveted configuration can
require relatively tight tolerances and/or may result in a relatively low axial pull out force
for components held on the shaft 110.
[0055] Figures 3-7 illustrate one embodiment of a new cam assembly 100 that
can be used in the circuit breaker 10 and, more particularly, in the mechanism assembly
10m such as the one shown in Figure 2B, for example. The cam assembly 100 includes
a shaft 110 with at least one notch 112, typically a series of closely spaced notches 112,
that cooperate with at least one self-locking retaining ring 120, typically only requiring a
single ring 120. The shaft 110 holds the cam C.
[0056] The cam C may comprise with multiple cooperating cam components,
shown as three matable components, 130,132,134. However, the cam C can be
provided as a single component, two components or more than three components. The
matable components can include aligned apertures 138 sized and configured to snugly
receive the shaft 110. The apertures 138 can include a shaped segment, which may
comprise a flat segment 138f for proper alignment.
[0057] Referring to Figure 6, the cam assembly 100 can include the shaft 110
with the at least one notch 112, a multiple component cam C held by the shaft 110, and
the at least one ring 120. The ring 120 includes circumferentially spaced apart, radially
inwardly extending fingers 121 that engage a notch 112 (recess) in the shaft 110.
Depending on the assembled width of the components, the ring 120 can engage different
ones of the notches 112 while providing a tight locking engagement with a large axial
pull off force. The use of at least one notch 112 with the self-locking ring 120 can
provide a 1 OX increase in axial retention, e.g., in pull out force over a corresponding
constant diameter shaft.
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[0058] In some embodiments, the shaft 110 with the at least one notch 112 can
have a pull out force that is between about 100 Ibfto about 1000 lbf(axially), more
typically between about 200 lbfand 800 lbf, such as between about 300 lbf and 600 Ibf
while allowing flexibility in and/or immunity to different stack up dimensions for the
components.
[0059] This assembly configuration allows for any number of stamped and/or cast
parts to be assembled onto a shaft 110 and secured using a self-locking ring 120.
Advantageously, the assembly configuration does not require precision machined
components and is stack-up tolerance friendly so as to be able to accommodate a larger
dimensional tolerance associated with multiple assembly configurations. Thus, while the
shaft configuration is discussed primarily for a cam assembly 100, it can be used for other
assemblies having a shaft that holds multiple components, typically multiple cooperating
components, and can allow for different more cost effective components, such as cast and
stamped components, with a greater tolerance range in part thickness.
[0060] The shaft 110 can also include a hub 115 that is axially spaced apart from
the at least one notch 112 to form an end stop for the cam C to define the desired axial
position of the cam C on the shaft 110 between the notch(es) 112 and the hub 115. The
hub 115 can be an integral feature of the shaft or may be provided by an attached member
which can be threaded, welded, frictionaliy engaged and/or welded. In yet another
embodiment, another set of notches spaced apart from the first set of notches 112 can be
provided with another at least one locking ring to form the end stop (not shown) without
requiring the hub 115 or for locking engagement of the hub 115.
[0061] As shown in Figures 3 and 7, for example, the shaft 110 can include at
least one external, longitudinally extending flat surface HOf, typically two symmetrically
opposing flat surfaces HOf, that can extend through the notches 112. As shown the
notches 112 are discontinuous about a perimeter of the shaft with opposing perimeter
portions of respective notches separated by at least one flat segment HOf.
[0062] In the embodiment shown in Figure 6, the components of the cam C can
be assembled together via spaced apart longitudinally extending pins 137, at least one
residing on opposite sides of the shaft aperture 138. Although shown as two pins 137, a
single pin or more than two pins can be used. In other embodiments, other attachment
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members or configurations can be used. Additional parts such as a bearing or bearings
can be installed between cam components, e.g., components 130,132 to perform
additional cam functions, for example.
[0063] The shaft 110 and/or cam C (e.g., components, 130,132,134) can
comprise a cast or stamped metal, powder metal and/or metal alloy with a suitable
hardness. In some particular embodiments, the shaft 110 is die cast metal with an
integral hub 115 and integrally cast notches 112. In some embodiments, the notches 112
can be formed after casting or stamping. The shaft 110 and/or cam C can comprise a nonferromagnetic
material.
[0064] Figure 8A illustrates an enlarged view of an end portion of the shaft 110
to illustrate that the shaft 110 can have a series of tightly spaced apart notches 112 of the
same size or various sizes and spacing, typically at least two notches 112 within about
0.025 inches of each other. In some embodiments, notch centerlines can reside within a
distance "x" ofeach other, typically within about 0.050 inches of each other. The
distance "x" can be less than or greater than 0.050 inches, including about 0,010 inches,
about 0.015 inches, about 0.020 inches, about 0.025 inches, about 0.030 inches, about
0.035 inches, about 0.040 inches, about 0.045 inches and the like, depending on stack up
tolerances allowed and degree of snugly locking engagement to prevent axial movement
desired. The tighter or closer the spacing between notches, the tighter the tolerance
resolution.
[0065] The shaft 110 can be configured so that 0B- 0A is between about 0.005 to
about 0.020 inches, such as about 0.005 inches, about 0.010 inches, about 0.015 inches
and about 0.020 inches. The outer wall segment diameter 0B can be the same as the
outer diameter of the shaft 110 at a location adjacent the notched segment llOn. In other
embodiments, the outer wall segment diameter 0B can be greater or even less than the
outer wall diameter of the shaft at a location away from the notched zone.
[0066] The outer wall segment 113 can project a distance "c" beyond an adjacent
notch outer wall surface. The distance "c" (or "groove or notch height") can vary or be
the same and is typically between about 0.001 to about 0.010 inches, such as about 0.002,
about 0.003, about 0.004, about 0.005, about 0.006, about 0.007, about 0.008, about
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0.009 and about 0.010 inches (average), for example. In some embodiments, the distance
"c" is about 0.005 inches.
[0067] The locking ring 120 can have an inner diameter defined by the innermost
free ends that together define the inner diameter of the ring which is sized less than the
outer diameter 0B so that the fingers 121 can flex to reside inside a notch 112 while
locking against axial movement using the ledge formed by the adjacent outer wall
segment 113. The ring 120 can have a solid outer diameter segment and the fingers 121
can extend freely (e.g., have an inwardly facing free end) to provide a desired locking
engagement with a respective notch 112. The locking ring can have various outer
diameters and can have an inner diameter that is dictated by the size of the cooperating
shaft to define an interior edge of the inner free end of the fingers 121. An exemplary
self-locking external retaining ring is available from McMaster-Carr® under part number
98430A152 and provides exemplary dimensions.
[0068] Although shown in Figure 8A as a series of six closely spaced notches
112, other numbers of notches may be used such as between 1-100 notches 112, or
between 5-50 notches 112, for example. For example, one notch or more than one notch
including, for example, two, three, four, five or six notches or more than six notches may
be used, e.g., 6-10, 10-20,20-30, 30-40,40-50 and the like. Each notch 112 can be
spaced apart and separated by pairs of outer protruding wall segments 113. The outer
wall segments 113 can have the same width "D" or different widths and the same outer
diameter 0B or different outer diameters 0B. The notches 112 can have the same width
E and the same diameter 0A or different widths E with the same diameters 0A or
different widths E and different diameters 0A.
[0069] Figure 8B is a table illustrating different dimensions and associated pull
off forces (pounds/lbs) measured. The notched configuration with the single locking ring
120 provided about a 10X increase in pull out forces over an un-notched shaft of
diameters of about 0.875 inches, 0.880 inches and 0.885 inches. The maximum measured
pull-off force was obtained using sample 9 with the noted dimensions.
[0070] In some embodiments, the circuit breakers 10 can be DC circuit breakers,
AC circuit breakers, or both AC and DC circuit breakers.
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[0071] In some particular embodiments, as shown in Figure 9, the circuit breaker
10 with the cam assembly 100 with the new shaft 110 and self locking ring 120 can be an
low voltage air circuit breaker such as a MAGNUM low voltage air circuit breaker or a
medium voltage vacuum circuit breaker such as the Minivac™ breaker, both are from
Eaton Corporation,
[0072] The circuit breakers 10 can be rated for voltages between about 1 V to
about 5000 volts (V) DC and/or may have current ratings from about 15 to about 2,500
Amperes (A). However, it is contemplated that the circuit breakers 10 and components
thereof can be used for any voltage, current ranges and are not limited to any particular
application as the circuit breakers can be used for a broad range of different uses.
[0073] The circuit breakers 10 can be a bi-directional direct current (DC) molded
case circuit breaker (MCCB). See, e.g., US Patent Nos. 5,131,504 and 8,222,983, the
contents of which are hereby incorporated by reference as if recited in full herein. The
DC MCCBs can be suitable for many uses such as data center, photovoltaic, and electric
vehicles applications.
[0074] As is known to those of skill in the art, Eaton Corporation has introduced a
line of molded case circuit breakers (MCCBs) designed for commercial and utility scale
photovoltaic (PV) systems. Used in solar combiner and inverter applications, Eaton
PVGard™ circuit breakers are rated up to 600 amp at 1000 Vdc and can meet or exceed
industry standards such as UL 489B, which requires rigorous testing to verify circuit
protection that meets the specific requirements of PV systems. However, it is
contemplated that the circuit breakers 10 can be used for various applications with
corresponding voltage capacity/rating.
[0075] The foregoing is illustrative of the present invention and is not to be
construed as limiting thereof. Although a few exemplary embodiments of this invention
have been described, those skilled in the art will readily appreciate that many
modifications are possible in the exemplary embodiments without materially departing
from the novel teachings and advantages of this invention. Accordingly, all such
modifications are intended to be included within the scope of this invention. Therefore, it
is to be understood that the foregoing is illustrative of the present invention and is not to
be construed as limited to the specific embodiments disclosed, and that modifications to
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the disclosed embodiments, as well as other embodiments, are intended to be included
within the scope of the invention.

We claim:
1. A cam assembly for a circuit breaker, comprising:
a shaft comprising at least one notch;
a cam held on the shaft; and
at least one self-retaining locking ring that engages a respective one of the at.least
one notch to lock the cam in an axial position on the shaft.
2. The cam assembly of Claim 1, farther comprising a hub held on the shaft
longitudinally spaced apart from the at least one notch, wherein the cam is locked in the
axial position on the shaft between the hub and locking ring.
3. The cam assembly of Claim 1 or 2, wherein the at least one notch is a plurality
of closely spaced circumferentially extending notches.
4. The cam assembly of any of Claims 1- 3, wherein centerlines of at least one
pair of adjacent notches are spaced apart between about 0.001 inches to about 0.020
inches.
5. The cam assembly of any of Claims 1-4, wherein the cam comprises a plurality
of cooperating components that are held in abutting contact on the shaft at a desired axial
location using the at least one self-locking retaining ring.
6. The cam assembly of any of Claims 1-5, in combination with a circuit breaker
having a housing with the cam assembly held inside the housing, and wherein the shaft
and cam are non-ferromagnetic cast metal or metal alloy components.
7. The cam assembly of any of Claims 1-6, wherein the at least one notch
comprises at least one circumferentially extending notch that is discontinuous about a
perimeter of the shaft with opposing perimeter portions of a respective notch being
separated by at least one flat segment.
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8. The cam assembly of any of Claims 1-7, wherein the at least one notch is a
plurality of circumferentially extending notches with wall segments having a greater
outer diameter residing therebetween, and wherein the wall segments have a substantially
constant width in a longitudinal direction of the shaft that is between about 0.0.10 and
0.020 inches, on average and the notches have a substantially constant width in the
longitudinal direction of the shaft that is between about 0.010 inches to about 0.020
inches, on average, and a depth that is between about 0.001 inches to about 0.010 inches,
on average.
9. The cam assembly of any of Claims 1-8, wherein the at least one notch is a
plurality of circumferentially extending longitudinally spaced apart external notches with
a depth of about 0.005 inches, average, and a substantially constant width in a
longitudinal direction of the shaft that is between about 0.010 inches and about 0.015
inches, average.
10. The cam assembly of any of Claims 1-9, wherein the at least one notch is a
plurality of circumferentially extending external notches spaced apart in a longitudinal
direction of the shaft with a respective width and with wall segments having a greater
outer diameter than a diameter or diameters of the notches residing therebetween, the
wall segments having a respective width that is less than the width of the notches.
11. The cam assembly of any of Claims 1-9, wherein the at least one notch is a
plurality of circumferentially extending external notches spaced apart in a longitudinal
direction of the shaft with a respective width and with wall segments having a greater
outer diameter residing therebetween, the wall segments having a respective width that is
the same as the width of the notches.
12. The cam assembly of any of Claims 1-9, wherein the at least one notch is a
plurality of circumferentially extending external notches spaced apart in a longitudinal
direction of the shaft with a respective width and with wall segments having a greater
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outer diameter residing therebetween, the wall segments having a respective width that is
greater than the width of the notches.
13. The cam assembly of any of Claims 1-12, wherein the at least one locking
ring engages a respective notch to define an axial pull off force that is between about 100
lbf to about 1000 lbf.
14. A mechanism assembly for circuit breaker, comprising:
a cam assembly, comprising:
a shaft comprising at least one circumferentially extending externa! notch;
a cam held on the shaft; and
at least one self-retaining locking ring that engages at least one of the at
least one notch to lock the cam in axial position on the shaft; and
a rotating contact arm in communication with the cam assembly.
15. The mechanism assembly of Claim 14, wherein the cam comprises a plurality
Of components in abutting contact on the shaft, and wherein the at least one notch
comprise a plurality of notches that are longitudinally spaced apart along the shaft with a
pitch that accommodates dimensional build tolerances of the cam components.
16. The mechanism assembly of Claim 14 or 15, wherein the at least one notch is
a plurality of closely spaced circumferentially extending notches with centerlines of
adjacent notches spaced between about 0.001 inches to about 0.020 inches apart.
17. The mechanism assembly of any of Claims 14-16, wherein the cam comprises
a plurality of cooperating components that are held in abutting contact at a defined axial
location on the shaft using the at least one locking ring and at least one of the at least one
external notch, and wherein the shaft and cam are non-ferromagnetic components.
18. The mechanism assembly of any of Claims 14-17, wherein the at least one
notch has a substantially constant width and is discontinuous in a circumferential
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direction with opposing perimeter portions separated by at least one flat segment, and
wherein the cam is non-ferromagnetic and comprises cast metal or metal alloy
components.
19. A shaft comprising:
an elongate shaft having a plurality of closely spaced apart circumferentially
extending external notches with wall segments having a greater outer diameter than an
outer diameter of the notches residing therebetween, wherein the notches have a width
that is between about 0.010 inches to about 0.020 inches, on average, and a depth that is
between about 0.001 inches to about 0.010 inches, on average, wherein the shaft is
configured to engage a locking ring using at least one of the external notches to lock
components in an axial position on the shaft.
20. The shaft of Claim 19, wherein the shaft is non-ferromagnetic, and wherein
the notches have a depth of about 0.005 inches, average, and a width between about
0.010 inches and about 0.015 inches, average.
21. The shaft of Claim 19 or 20, in combination with at least one self-retaining
locking ring that engages at least one of the notches to axiaily lock into position on the
shaft and provide a pull out force that is between about 100 lbf to about 1000 Ibf.