Electric heating – Heating devices – With current connection and/or disconnection means
Reexamination Certificate
1999-05-07
2002-02-26
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
With current connection and/or disconnection means
C219S521000, C099S338000, C099S390000, C200S00100B, C200S283000
Reexamination Certificate
active
06350970
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to heating appliances, such as toasters or toaster ovens, and more specifically to a switch mechanism for such appliances' bread support.
BACKGROUND OF THE INVENTION
In heating appliances, such as toasters and toaster ovens, a food item is placed on a bread support that supports the food item as it is lowered into and removed from a bread cavity of the appliance.
FIG. 1
is an isometric view of a conventional toaster
10
with its external housing (not shown) removed to better illustrate the internal components of the toaster
10
. The toaster
10
includes a shell
14
formed from two side panels
16
,
17
, two end panels
18
,
20
, and a bottom
22
that are secured to each other by suitable means. An outer bread guard
26
is positioned inside the side panel
16
and an identical outer bread guard
28
is positioned inside the side panel
17
. Two inner bread guards
32
and
34
are also positioned between the outer guards
26
and
28
. Each of the bread guards
26
—
34
includes a horizontal member
36
and vertical members
38
. A first bread cavity
40
is defined between the bread guards
26
and
32
, and a second bread cavity
42
is defined between the bread guards
28
and
34
. The bread guards
26
-
34
function to protect bread placed between the bread guards from heating elements (not shown in
FIG. 1
) positioned inside the side panels
16
and
17
as well as between the center bread guards
32
and
34
.
A first bread support (not shown) is contained within the first bread cavity
40
and functions to support a piece of bread as it is lowered into and raised from the bread cavity
40
. A second bread support (not shown) is similarly positioned within the second bread cavity
42
to support another piece of bread in the bread cavity
42
. Each of the bread supports includes a lever
46
,
48
extending through respective slots
50
and
52
in the end panel
18
. The levers
46
,
48
are coupled to respective slides
56
,
58
that slide on respective vertically oriented rods
60
,
62
. The slides
56
,
58
are straddled by respective brackets
74
,
76
that also slide along the respective rods
60
,
62
. The brackets
74
,
76
are coupled to an actuating handle
78
positioned outside the housing (not shown). The toaster
10
further includes an edge panel
80
positioned at the bottom of the end panel
18
. A switch mechanism and retainer
82
is mounted on the edge panel
80
.
In operation, the actuating handle
78
is pushed down to cause the brackets
74
,
76
to slide downwardly on the respective rods
60
,
62
. As the brackets
74
,
76
slide downwardly, they perform two functions. First, the brackets
74
,
76
allow their respective slides
56
,
58
to move downwardly until they contact respective stops (not shown in FIG.
1
). The slides
56
,
58
allow the levers
46
,
48
to move downwardly to lower the bread on the bread supports in the bread cavities
40
,
42
. As the levers
46
,
48
are pushed down, the outer bread guards
26
,
28
move toward the center of the corresponding bread cavity
40
,
42
, as shown for the bread guard
28
. In this way, the bread guards
26
-
34
position the bread in approximately the centers of the bread cavities
40
and
42
so that the bread placed on the bread supports is not positioned too close to the heating elements.
Second, when the brackets
74
,
76
reach their lower positions, they actuate a switch (not shown) in the switch mechanism and retainer
82
to apply power to the heating elements of the toaster
10
during a heating cycle. The brackets
74
,
76
are held in their lowered position during the heating cycle by an electromagnet (not shown) in the switch mechanism and retainer
82
. At the end of the heating cycle, the electromagnet releases the brackets
74
,
76
, thereby allowing the brackets
74
,
76
to be pulled upwardly by a spring (not shown in
FIG. 1
) extending between the brackets
74
,
76
and a fixed location on the toaster
10
. As the brackets
74
,
76
move up, they raise the slides
56
,
58
, respectively, which, in turn, raise the respective levers
46
,
48
thereby raising the bread supports in the bread cavities
40
,
42
, respectively. Although the switch mechanism and retainer
82
is described as controlling the toasting time, one skilled in the art will realize that other mechanisms such as a mechanical heat sensing mechanism may also be utilized.
FIGS. 2A-2C
are schematic diagrams showing one of the brackets
74
and associated components to illustrate the operation of the toaster
10
bread support. Referring to
FIG. 2A
, the bread support bracket
74
includes a top leg
92
, a side leg
94
and a bottom leg
96
. The top leg
92
and the bottom leg
96
are formed to slide along the rod
60
. A spring
98
is connected between one of the legs
92
-
96
and a fixed structure of the toaster such as the end panel
18
(FIG.
1
). In
FIG. 2A
, the spring
98
is connected to the top leg
92
, and functions to apply a return force F
R
to the bread support bracket
74
biasing the bread support bracket
74
towards a top end
100
of the rod
60
. The bracket
74
is shown in
FIG. 2A
in its OFF position before the handle
78
(
FIG. 1
) has been actuated downwardly to begin a heating cycle. In this position, the slide
56
, which is connected to the bread support, rests on an upper surface of the bottom leg
96
. The slide
56
thus maintains the bread support in its upper position.
In
FIG. 2B
, an external force F
E
is applied to the bread support bracket
74
sliding the bracket
74
bread support towards a bottom end
102
of the rod
60
. As the bread support bracket
74
slides along the rod
60
, the slide
56
carrying the bread support is allowed to move downwardly along the rod
60
towards the bottom end
102
. The slide
56
continues to move downwardly until it contacts a stop
110
, which is shown in FIG.
2
B. Although a discrete stop
11
is shown in
FIG. 2B
, it will be understood that the stop
110
may be implemented in other ways such as limiting the downward movement of the bread support. After the slide
56
contacts the stop
110
, the bracket
74
may continue to be displaced downwardly because the upper leg
92
is spaced from the lower leg
96
by a distance that is greater than the height of the slide
56
. However, when the upper leg
92
of the bracket
74
contacts the slide
56
as shown in
FIG. 2B
, the bracket
74
has reached its lower-most position. In this position, the bracket
74
closes a switch (not shown) in the switch mechanism and retainer
82
to causing power to be applied to electronic circuitry and thereby initiating a heating cycle of the toaster
10
. When power is supplied to the electronic circuitry, a coil (not shown) is energized and generates a retaining force F
C
that secures the bracket
74
in the position shown in
FIG. 2B
during the heating cycle of the toaster
10
. The retaining force F
C
generated by the coil must be greater than the return force F
R
from the spring
98
in order to hold the bracket
74
at the desired position.
As shown in
FIG. 2C
, at the end of the heating cycle, which is determined by a timer (not shown) in the switch mechanism and retainer
82
, the electromagnet removes the retaining force F
C
, thereby allowing the spring
98
to slide the bracket
74
upwardly along the rod
60
. The lower leg
96
of the bracket
74
then contacts the slide
56
to raise the slide
56
, and hence the bread support, along with the bracket
74
to the OFF position shown in FIG.
2
A.
As is well known in the art, it is possible for a food item to get caught in the bread cavity
40
during a heating cycle. In such cases, the food item can prevent the bread support from being carried upwardly by the spring
98
coupled through the bracket
74
. The bracket
74
and slide
56
will then be stuck in the position shown in FIG.
2
C. However, even though the stuck slide
56
prevents the bracket
74
from moving u
Dorsey & Whitney LLP
Jeffery John A.
Salton Inc.
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