Electrical switch with limited contact arcing

Details Electrical switch with limited contact arcing Electrical switch with limited contact arcing

2002-12-11

2004-05-18

Donovan, Lincoln (Department: 2832)

Electricity: circuit makers and breakers

Solid contact

Reciprocating actuator

C200S538000, C200S548000

Reexamination Certificate

active

06737598

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention generally relates to an electrical switch for use in high current and high voltage applications. More particularly, certain embodiments of the present invention relate to an electrical switch that reduces arcing when contacts make and break connections.
A wide variety of electrical switches have been proposed for various industrial and commercial applications. Some examples of industrial and commercial applications relate to power tools, electric motors, heating and air conditioning systems, and the like. These varied electrical switches are adapted to operate in high current and/or high voltage applications, as well as with AC and/or DC power supplies.
In general, electrical switches used in high current and high voltage applications include a contact carriage that is moveable within a switch housing. The contact carriage carries contacts that make and break electric connections with associated contacts mounted in the switch housing.
FIG. 1
illustrates a top isometric view of a conventional switch housing
10
and a contact carriage
12
removed therefrom. The contact carriage
12
is configured to be moveably mounted within the switch housing
10
. The switch housing
10
includes side walls
5
, end walls
7
and a bottom
9
that collectively define an interior chamber
11
. The switch housing
10
includes contact posts
14
and
15
that are rigidly mounted within the chamber
11
and located proximate front and rear ends
42
and
43
, respectively, of the switch housing
10
. The contact posts
14
and
15
include faces
16
and
19
, respectively, directed toward one another. The bottom
9
of the switch housing
10
is formed with parallel ribs
13
extending between the front and rear ends
42
and
43
of the switch housing
10
. A space between the ribs
13
forms a channel
15
that similarly extends between the front and rear ends
42
and
43
. The side walls
5
include stepped interior surfaces
3
that are cut by a notch
17
which extends laterally across the interior chamber
11
. The notch
17
extends through the ribs
13
and through the channel
15
.
The contact carriage
12
includes a body
26
that extends along a longitudinal axis
22
. The body
26
includes a front face
21
. The contact carriage
12
is configured to be inserted into the chamber
11
of the switch housing
10
with the front face
21
of the contact carriage
12
turned to face the bottom
9
of the switch housing
10
. With reference to
FIG. 1
, before insertion into the switch housing
10
, the contact carriage
12
as shown
FIG. 1
is rotated 180 degrees about the longitudinal axis
22
until the front face
21
of the contact carriage
12
faces the bottom
9
of the switch housing
10
.
The body
26
of the contact carriage
12
includes support posts
28
and
34
formed on the front face
21
proximate opposite ends of the body
26
. A pair of C-shaped supports
30
and
32
are also provided on the front face
21
of the body
26
and arranged to face in opposite directions along the longitudinal axis
22
. The C-shaped supports
30
and
32
are positioned near corresponding support posts
28
and
34
. The support post
28
and the C-shaped support
30
are separated by a gap that receives a contact bridge
18
. The support post
34
and C-shaped support
32
are separated by a gap that receives contact bridge
20
. Contact bridges
18
and
20
are oriented parallel to one another and transverse to the longitudinal axis
22
. The C-shaped supports
30
and
32
receive springs
36
and
37
, respectively, that bias contact bridges
18
and
20
, respectively, outward against support posts
28
and
34
. The contact bridges
18
and
20
include contact pads
24
and
25
, respectively, facing outward in opposite directions. The contact bridges
18
and
20
are permitted to move along the longitudinal axis
22
within a limited range of motion.
The support posts
28
and
34
include tip portions
29
and
35
, respectively, extending upward away from the front face
21
. When the contact carriage
12
is loaded into the chamber
11
, the contact tips
29
and
35
are turned down to rest in, and slide along, the channel
15
formed between the ribs
13
. Hence, ribs
13
and tip portions
29
and
35
cooperate to control the direction of motion of the contact carriage
12
with respect to the switch housing
10
during operation. Once the contact carriage
12
is loaded into the chamber
11
, the contact bridges
18
and
20
are aligned with contact posts
14
and
15
, respectively, such that pads
24
on contact bridge
18
align with faces
16
on contact posts
14
. Similarly, pads
25
on contact bridge
20
align with faces
19
on contact posts
15
. As the contact carriage
12
is slid in the direction of arrow A, pads
24
engage faces
16
to form an electrical connection through contact bridge
18
and between contact posts
14
. When the contact carriage
12
is slid in the direction of arrow B, pads
25
engage faces
19
to afford an electrical connection through contact bridge
20
between contact posts
15
. Only one of contact bridges
18
and
20
is electrically connected with the corresponding contact posts
14
and
15
, respectively, at any single point in time. Hence, when contact bridge
18
engages contact posts
14
, contact bridge
20
is disengaged from contact posts
15
, and vice versa.
FIG. 2
illustrates a partial end isometric view of the contact carriage
12
to better illustrate a dielectric hood
46
mounted on the body
26
. The dielectric hood
46
is configured to reduce arcing by separating the contact bridge
20
from the contact posts
15
when the contact carriage
12
is moved in the direction of arrow A. The dielectric hood
46
includes a central beam
48
located above, and extending parallel to, the contact bridge
20
. Opposite ends
47
of the central beam
48
are held within notch
17
(
FIG. 1
) in the stepped interior surfaces
3
of the side walls
5
. The central beam
48
is slidably mounted to legs
49
provided on the body
26
. The notch
17
holds the central beam
48
at a fixed position in the chamber
11
. Hence, when the contact carriage
12
moves within chamber
11
, the dielectric hood
46
moves relative to the body
26
.
A pair of isolation flaps
50
and
52
are mounted on opposite ends of the central beam
48
proximate the pads
25
(shown in dashed lines in
FIG. 2
) on opposite ends of the contact bridge
20
. The isolation flaps
50
and
52
are curved in an L-shape as shown in
FIG. 2
to extend forwardly from the central beam
48
and to curve downward toward the body
26
. When the central beam
48
is moved in the direction of arrow C with respect to the body
26
, the central beam
48
rotates in the direction of arrow D until the isolation flaps
50
and
52
cover the pads
25
on the front of the contact bridge
28
. When the central beam
48
is moved in the direction of arrow E with respect to the body
26
, the central beam
48
is rotated in the direction of arrow F, causing the isolation flaps
50
and
52
to pivot upward to expose the pads
25
on the contact bridge
20
.
FIG. 1
illustrates the dielectric hood
46
moved to a position at which the contact bridge
20
and the pads
25
are entirely exposed to faces
19
on the contact posts
15
.
Returning to
FIG. 1
, when the contact carriage
12
is loaded into the switch housing
10
, opposite ends
47
of the central beam
48
are received within the notch
17
. As the contact carriage
12
is moved in the direction of arrow A, the notch
17
holds the central beam
48
in a fixed position relative to the switch housing
10
, thereby causing the relative motion between the dielectric hood
46
and the body
26
of the contact carriage
12
in the direction of arrow C (
FIG. 2
) which in turn causes the central beam
48
to rotate in the direction of arrow D to cover pads
25
on the contact bridge
20
with the isolation flaps
50
and
52
. In reverse, when the

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