CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from and claims the benefit of U.S.
Patent Application Serial No. 14/542,765, riled November 17, 2014, which is
incorporated by reference herein.
10 BACKGROUND
Field
The disclosed concept pertains generally to vacuum switching
apparatus and, more particularly, to vacuum switching apparatus such as for example,
vacuum interrupters. The disclosed concept also pertains to contact assemblies for
15 vacuum switching apparatus. The disclosed concept further pertains to methods of
securing an electrical contact to an electrode in vacuum switching apparatus.
Background information
Some circuit breakers such as. for example, power circuit breakers,
employ vacuum interrupters as the switching devices. Vacuum interrupters generally
20 include separable electrical contacts disposed on the ends of corresponding electrodes
within an insulating housing. The electrical contacts are typically mechanically and
electrically connected to the electrodes by brazing. While further components of the
vacuum interrupter are being assembled with the electrode/electrical contact
assembly, it is important to keep the mating between the electrode/electrical contact
25 secured. Known practices for securing this connection involve employing a contact
weight on top of the electrical contact. However, employing a contact weight has
disadvantages. For example, while the vacuum interrupter is brazed in a furnace, the
contact weight requires an additional expenditure of energy by the furnace.
Additionally, employing a contact weight creates a risk that the electrical contacts will
30 not be properly positioned, which can result in poor brazing of the joint between
them, leading to an undesirable increase in electrical resistance of that joint and of the
entire vacuum interrupter. There are also situations when the use of a positioning
weight is prohibited, for example and without limitation, when the entire vacuum
interrupter is to be brazed in a single vacuum brazing furnace run.
There is, therefore, room for improvement in vacuum switching
apparatus, and in contact assemblies and methods of securing an electrical contact to
5 an electrode therefor.
SUMMARY
These needs and others are met by embodiments of the disclosed
concept, which are directed to a contact assembly and associated method of securing
10 an electrical contact to an electrode in vacuum switching apparatus.
m accordance with one aspect of the disclosed concept, a contact
assembly for a vacuum switching apparatus is provided. The vacuum switching
apparatus includes a vacuum envelope. The vacuum envelope has an interior. The
contact assembly comprises: a number of electrical contacts disposed in the interior of
15 the vacuum envelope, at least one electrical contact having a hole; and a number of
electrodes each engaging a corresponding one of the number of electrical contacts, at
least one electrode comprising a base and a protrusion. The protrusion extends from
the base into the hole of the electrical contact in order to secure the electrical contact
to the electrode.
20 As another aspect of the disclosed concept. a vacuum switching
apparatus comprises: a vacuum envelope having an interior; and a contact assembly
comprising: a number of electrical contacts disposed in the interior of the vacuum
envelope, at least one electrical contact having a hole, and a number of electrodes
each engaging a corresponding one of the number of electrical contacts, at least one
25 electrode comprising a base and a protrusion. The protrusion extends from the base
into the hole of the electrical contact in order to secure the electrical contact to the
electrode.
As another aspect of the disclosed concept, a method of securing an
electrical contact to an electrode in a vacuum switching apparatus is provided. The
30 vacuum switching apparatus includes a vacuum envelope having an interior. The
electrode comprises a base and a protrusion extending from the base. The electrical
contact has a hole. The electrical contact is disposed in the interior of the vacuum
envelope. The method comprises the steps of: inserting the protrusion into the hole of
the electrical contact; and deforming the protrusion in order to secure the electrical
contact to the electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
A full understanding of the disclosed concept can he gained from the
following description of the preferred embodiments when read in conjunction with the
accompanying drawings in which:
Figure 1is a simplified section view of a contact assembly in
accordance with an embodiment of the disclosed concept, shown before the electrical
contact is secured to the electrode;
Figure 2 is a simplified section view of the contact assembly of Figure
1, shown with the electrode extending into the electrical contact and with a
component of a tooling apparatus;
Figure 3 is a simplified section view of the contact assembly and
component of the tooling apparatus of Figure 2, also showing additional features of
the tooling apparatus;
Figure 4A is a simplified section view of the contact assembly of
Figure 2, modified to show the electrical contact secured to the electrode;
Figure 4B is a simplified top plan view of the contact assembly of
Figure 4A;
Figure 4C is an enlarged section view of a portion of the contact
assembly of Figure 4A;
Figure 5 is a section view of a vacuum switching apparatus and contact
assembly therefor, in accordance with an embodiment of the disclosed concept; and
Figure 6 is a section view of a vacuum switching apparatus and contact
assembly therefor, in accordance with an alternative embodiment of the disclosed
concept.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For purposes of the description hereinafter, directional phrases used
herein such as, for example "up", "down' 5, "top", "bottom' 5, and derivatives thereof
shall relate to the disclosed concept, as it is oriented in the drawings. It is to be
understood that the specific elements illustrated in the drawings and described in the
following specification are simply exemplary embodiments of the disclosed concept.
Therefore, specific orientations and other physical characteristics related to the
5 embodiments disclosed herein are not to be considered limiting with respect to the
scope of the disclosed concept.
As employed herein, the term "number" shall mean one or an integer
greater than one {i.e., a plurality).
As employed herein, the statement that two or more parts are
10 "connected" or "coupled" together shall mean that the parts are joined together either
directly or joined through one or more intermediate parts. Further, as employed
herein, the statement that two or more parts are "attached" or "affixed" shal l mean
that the pans are joined together directly.
As employed herein, the statement that two or more parts or
15 components "engage" one another shall mean that the parts touch and/or exert a force
against one another either directly or through one or more intermediate parts or
components.
As employed herein, the term "coupling member" refers to any
suitable connecting or tightening mechanism expressly including, but not limited to,
20 screws, rivets, bolts and the combinations of bolts and nuts (e.g., without limitation,
lock nuts) and bolts, washers and nuts.
As employed herein, the term "vacuum envelope" means an envelope
employing a partial vacuum therein.
Figure 1 shows a contact assembly 100 (shown in simplified form) for
25 a vacuum switching apparatus such as, for example and without limitation, a vacuum
interrupter 400 (shown in simplified form in Figure 5). In the example of Figure I,
the contact assembly 100 includes an electrical contact 110 and an electrode 120,
before the electrical contact 110 has been secured to the electrode 120. As seen, the
electrical contact 110 has a hole (e.g., without limitation, thru hole 112), and the
30 electrode 120 includes a base 122 and a protrusion 124 extending from the base 122.
The protrusion 124 has a cavity 126, the purpose of which will be described below.
In operation, the protrusion 124 extends into the thru hole 112 in order to secure the
electrical contact 110 to the electrode 120 (see for example Figure 2, which shows the
electrode 120 engaging the electrical contact 110).
Figure 3 shows a tooling apparatus 2 mounted on the contact assembly
100. The tooling apparatus 2 generally includes a component (e.g., without
5 limitation, rivet tool 4), a body portion 6.. a cap 8, and a housing 10. The body portion
6 has a thru hole 12. In order to assemble the tooling apparatus 2, the rivet tool 4 is
inserted through the thru hole 12. The cap 8 has a thru hole 16. The tooling apparatus
2 further includes a number of coupling members (three coupling members 18,26,28
are shown). To secure the cap 8 to the rivet tool 4, the coupling member 18 is
10 inserted into the thru hole 16 of the cap 8 and an aperture 14 (shown in hidden line
drawing in Figure 2) of the rivet tool 4. In order to secure the housing 10 to each of
the body portion 6 and the cap 8, and therefore to the rivet tool 4, the housing 10 is
placed on the cap 8 such that the cap 8 extends through a corresponding thru hole 20
{three thru holes 20,22,24 are shown in Figure 3). Similarly, the coupling members
15 26,28 are inserted through the respective thru holes 22,24 and engage the body
portion 6.
The tooling apparatus 2 includes a spring 30 that extends from the
body portion 6 to the cap 8. The rivet tool 4 extends through the spring 30. The
spring 30 exerts a force on the body portion 6 and on the cap 8. In operation, the
20 tooling apparatus 2 secures the electrical contact 110 to the electrode 120. For
example and without limitation, when the rivet tool 4 moves into the thru hole 112
toward the base 122 of the electrode 120, and the rivet tool 4 pushes into the
protrusion 124, the protrusion 124 plastically deforms.
More specifically, when the cap 8 moves toward the electrical contact
25 110 (i.e., movement initiated by an operator), the cap 8 pushes into the rivet tool 4,
which in turn is driven into the cavity 126 of the electrode 120, plastically deforming
the protrusion 124 of the electrode 120 to form an electrode 120', as shown in Figure
4A (it will be appreciated that like reference numbers are used to represent like
features in Figure 4A). This process is known as ''staking" the rivet (i.e., the
30 protrusion 124), and it provides a mechanism to attach two components (i.e., the
electrode 120' is attached to the electrical contact 110). In other words, by deforming
(i.e., staking) the protrusion 124, the electrical contact 110 is secured to the resulting
electrode 120', which is advantageously prevented from being pulled through the
electrical contact 110.
As the cap 8 moves toward the electrical contact 110, the force exerted
by the spring 30 on each of the body portion 6 and the cap 8 advantageously
5 increases. In this manner, the amount of plastic deformation can be relatively
controlled for example and without limitation., although it is within the scope of the
disclosed concept for the rivet tool 4, or a similar suitable alternative tool (not shown),
to perform the desired deforming function without the other components of the
tooling apparatus 2 (see for example Figure 2, in which only the rivet tool 4 is
10 shown), employing the tooling apparatus 2 allows the amount of force exerted on the
protrusion 124 to be controlled. Specifically, by having the opposing force of the
spring 30 on the cap 8, and by having that force increase as the cap 8 moves toward
the electrical contact 110, the tooling apparatus 2 advantageously provides a
controlled mechanism to deform the protrusion 124, as desired.
15 When the rivet tool 4 is performing the desired deforming function, the
body portion 6 of the tooling apparatus 2 is advantageously aligned with the contact
assembly 100. As seen in Figure 3, the thru hole 112 of the electrical contact 110 has
a receiving portion 113, and the body portion 6 of the tooling apparatus 2 includes a
securing portion 7 that fits in the receiving portion 113. When the securing portion 7
20 is located in the receiving portion 113, the rivet tool 4 is positioned directly on top of
the cavity 126. As a result, when the rivet tool 4 drives down into the cavity 126 of
the protrusion 124, the rivet tool 4 is advantageously able to plastically deform the
protrusion 124 to form a consistent annular-shaped retaining portion 125'. It is,
however, within the scope of the disclosed concept for an electrical contact (not
25 shown) and body portion (not shown) to have any suitable alternative shape and/or
configuration in order to perform the desired function of aligning the rivet tool 4 with
the cavity 126.
Referring to Figures 4B and 4C, the electrical contact 110 includes an
annular-shaped internal ledge 114 located adjacent the thru hole 112 (Figure 4C). As
30 seen in Figure 4C, the protrusion 124' extends from the base 122' past the internal
ledge 114. The retaining portion 125' substantially overlays and engages the internal
ledge 114. The retaining portion 125' has an outer diameter 127' that is larger than an
inner diameter 115 of the interna! ledge 114. In this manner, the retaining portion
125' advantageously prevents the electrode 120' from becoming detached from (i.e.,
pulled through) the electrical contact 110, thus securing the electrical contact 110 to
the electrode 120'.
5 This connection advantageously allows the electrode 120' and the
electrical contact 110 to be brazed in a single furnace run with the rest of the vacuum
interrupter 400 (Figure 5). Additionally, employing the disclosed riveting concept
allows the electrical contact 110 and the electrode 120' io be more tightly mated
together. As a result, the quality of the vacuum brazing is advantageously improved,
10 because when the braze melts, it weeps up better along the tighter joint. Furthermore,
known methods of securing an electrical contact (not shown) to an electrode (not
shown) involving contact weights (not shown) can be eliminated. Consequently,
when the vacuum interrupters 400,500 undergo brazing undesirable expenditures of
energy previously associated with contact weights (not shown) can be eliminated.
15 Referring again to Figure 4A, the base 122' of the electrode 120'
includes an engaging surface 128' that engages the electrical contact 110 and faces in
a direction 132. The engaging surface 12S' is located in a plane 130 and the internal
ledge 114 is located in a plane 116 that is parallel to the plane 130. The direction 132
that the engaging surface 128' faces is perpendicular to the planes P6,130. More
20 precisely, the engaging surface 128' is substantially flush with the electrical contact
110 and exerts a force on the electrical contact 110 in the direction 132. The retaining
portion 125' exerts an opposing force on the electrical contact 110 in a direction
opposite the direction 132. Because the planes 116 130 are parallel to each other, the
retaining portion 125' and the engaging surface 128' are advantageously able to
25 provide a maximum clamping force on the electrical contact 110 to secure the
electrical contact 110 to the electrode 120'. This configuration advantageously
provides a relatively strong securement of the electrode 120' and the electrical contact
110 to prevent them from moving out of position while the contact assembly 100 is
further processed. Additionally, the configuration provides a relatively tight
30 geometric fit between the electrode 120' and the electrical contact 110,
advantageously allowing for a relatively void free mechanical and electrical
connection.
Figure 5 shows the aforementioned vacuum interrupter 400, including
the contact assembly 100 and a vacuum envelope 402. The contact assembly 100
further includes another electrical contact 210 and a corresponding electrode 220'
engaging the electrical contact 210. As seen, the vacuum envelope 402 has an interior
5 404 and each of the electrical contacts 110,2 10 are located in the interior 404. The
electrical contact 210 is opposite the electrical contact 110. Additionally, it will be
appreciated that the electrical contact 210 is secured to the electrode 220' in
substantially the same manner as the electrode 120' and the electrical contact 110.
Thus, advantages associated with the relatively secure mechanical/electrical
10 connection between the electrode 120' and the electrical contact 110 likewise apply to
the electrode 220' and the electrical contact 210.
Figure 6 shows another electrical switching apparatus (e.g., without
limitation, vacuum interrupter 500) that includes a vacuum envelope 502 having an
interior 504, and a contact assembly 300. The contact assembly 300 includes the
15 electrical contact 110 and the corresponding electrode 120'. In addition, the contact
assembly 300 includes another electrical contact 3 10 and an electrode 320 engaging
the electrical contact 310. The electrical contacts 110,310 are opposite each other and
are located in the interior 504 of the vacuum envelope 502. The electrode 320 does
not extend into the electrical contact 3 10. It will be appreciated that the electrical
20 contact 3 10 may be secured to the electrode 320 by any known method (e.g., without
limitation, brazing). Thus, the contact assembly 300 and associated vacuum
interrupter 500 include the electrical contact 110 and associated electrode 120'
secured in accordance with the disclosed staking concept, as well as the electrical
contact 310 and associated electrode 320 secured in accordance with known methods.
25 Accordingly, it will be appreciated that the disclosed concept provides
for an improved (e.g., without limitation, easier to manufacture, more energy
efficient, stronger mechanical/electrical connection between electrode/electrical
contact) vacuum switching apparatus (e.g., without limitation, vacuum interrupters
400,500), and contact assembly 100,300 and method of securing an electrical contact
30 110,2 10 to an electrode 120' ,220' therefor, which among other benefits, deforms (i.e.,
stakes) the protrusion 124 of the electrode 120 in a controlled manner, as desired.
Thus, a portion (i.e., retaining portion 125') of the resulting electrode 120'
advantageously prevents the electrode 120' from being pulled through the electrical
contact 110, thus securing the electrical contact 110 to the electrode 120'.
While specific embodiments of the disclosed concept have been
described in detail, it will be appreciated by those skilled in the art that various
modifications and alternatives to those details could be developed in light of the
overall teachings of the disclosure. Accordingly, the particular arrangements
disclosed are meant to be illustrati ve only and not limiting as to the scope of the
disclosed concept which is to be given the full breadth of the claims appended and
any and all equivalents thereof

What is Claimed is:
1. A contact assembly ( 100,300) for a vacuum switching apparatus
(400,500), said vacuum switching apparatus comprising a vacuum envelope
(402,502), the vacuum envelope having an interior (404,504), said contact assembly
comprising:
a number of electrical contacts ( 110,210,3 10) disposed in the interior
of the vacuum envelope, at least one electrical contact ( 110,210) having a hole ( 112);
and
a number of electrodes (120, I20\220\320) each engaging a
corresponding one of said number of electrical contacts, at least one electrode
(120,120',220') comprising a base (122,122') and a protrusion (124,1 24'),
wherein said protrusion extends from said base into the hole of said at
least one electrical contact in order to secure said at least one electrical contact to said
at least one electrode.
2. The contact assembly ( 100,300) of Claim 1wherein said at least one
electrical contact ( J 10) comprises an interna! ledge 14); wherein said internal ledge
is disposed adjacent the hole 12): wherein said protrusion ( 124') comprises a
retaining portion ( I25'); and wherein said retaining portion engages said internal
ledge.
3. The contact assembly (100,300) of Claim 2 wherein said internal ledge
) is annular-shaped; and wherein said protrusion ( 124') extends from said base
(122') past said internal ledge.
4. The contact assembly (100,300) of Claim 3 wherein said retaining
portion (125') is annular-shaped; and wherein said retaining portion substantially
overlays said internal ledge ) .
5. The contact assembly ( 100,300) of Claim 2 wherein said internal ledge
) is disposed in a first plane (116); wherein said base ( 122') comprises an
engaging surface (128') engaging said electrical contact 10); and wherein the
engaging surface is disposed in a second plane (130) parallel to the first plane.
6. The contact assembly ( 100,300) of Claim 5 wherein said protrusion
( 124') extends from said base ( 122') in a direction ( 132) perpendicular to the first
plane ( 116).
7. The contact assembly ( 100} of Claim 1 wherein said at least one
electrode ( 120,120',220') comprises a first electrode ( 120,1 20') and a second electrode
(220'); wherein said at least one electrical contact ( 110,210) comprises a first
electrical contact ( 110) and a second electrical contact (210) disposed opposite said
first electrical contact; wherein said first electrode engages said first electrical contact;
and wherein said second electrode engages said second electrical contact.
8. The contact assembly (300) of Claim 1 wherein said number of
electrodes (120J20',320) comprises another electrode (320); wherein said number of
electrical contacts ( 110,310) comprises another electrical contact (310) disposed
opposite said at least one electrical contact 10); wherein said another electrode
engages said another electrical contact; and wherein said another electrode does not
extend into said another electrical contact.
9. A vacuum switching apparatus (400,500) comprising:
a vacuum envelope (402,502) having an interior (404,504); and
a contact assembly (100,300) according to any of Claims l-S.
10. A method of securing an electrical contact 10,2 10) to an electrode
(120, 120' ,220') in a vacuum switching apparatus (400,500), said vacuum switching
apparatus including a vacuum envelope (402,502) having an interior (404,504), said
electrode comprising a base (122,122') and a protrusion (124,1 24') extending from
said base, said electrical contact having a hole ( 112), said electrical contact being
disposed in the interior of the vacuum envelope, said method comprising the steps of:
inserting said protrusion into the hole of said electrical contact; and
deforming said protrusion in order to secure said electrical contact to
said electrode.
11. The method of Claim 12 wherein the deforming step further comprises
providing a tooling apparatus (2) comprising a component (4);
moving said component into the hole ( 112) of said electrical contact
( 110) toward said base (122,122') of said electrode (120,120')); and
pushing said component into said protrusion ( 124, 124') in order to
deform said protrusion.
12. The method of Claim 11 wherein said electrical contact 10 }has an
internal ledge 14); wherein said protaision (124,1 24') has a cavity (126); and
wherein the pushing step further comprises:
driving said component (4) into the cavity, thereby forcing a portion
( 125') of said protrusion to substantially overlay said internal ledge.
13. The method of Claim 11 wherein said tooling apparatus (2) further
comprises a body portion (6). a cap (8), and a housing ( 10); wherein said body portion
has a thru hole (12); and wherein the method further comprises:
inserting said component (4) through the thru hole of said body
portion; and
securing each of said cap and said housing to said component.
14. The method of Claim 13 wherein said tooling apparatus (2) further
comprises a number of coupling members (18,26,28); wherein said component (4) has
an aperture (14); wherein said housing (10) has a number of thru holes (20,22,24);
wherein said cap (8) has a thru hole (16); and wherein the securing step further
comprises:
inserting one of said number of coupling members ( 18) into each of the
thru hole of said cap and the aperture of said component;
placing said housing on said cap, said cap extending through one of the
thru holes (20) of said housing; and
inserting a number of other coupling members (26,28) through a
corresponding number of other thru holes (22,24) of said housing, each of said
number of other coupling members engaging said body portion.
15. The method of Claim 13 wherein said tooling apparatus i2 ) further
comprises a spring (30); wherein said spring extends from said body portion (6) to
said cap (8); wherein said component (4) extends through said spring; wherein said
spring exerts a force on each of said cap and said body portion; and wherein the
pushing step further comprises:
moving said cap (8) toward said electrical contact 10), thereby
increasing the force exerted by said spring on each of said cap and said body portion.