WINDOWED OVEN DOOR HAVING SHEILD RAISING AND DOOR LOCKING SYSTEM

PORTE DE CUISINIERE A HUBLOT MUNIE D'UN SYSTEME D'ECRAN MOBILE ET DE VERROUILLAGE

English Abstract

A B S T R A C T


A windowed oven door for ranges having self-
cleaning ovens comprises a system for simultaneously
locking the door and raising a shield to cover the
window. A linkage mechanism in the shield raising
part of the system includes a pair of overcenter link
arms which are retained in their past dead center
position while the oven door is locked on an oven
during its self-cleaning cycle.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an oven door having spaced apart inner and outer
door panels with aligned window openings and at least one
transparent pane in each window opening, a linkage system
for raising and lowering a shield positioned between said
door panels, a rotatable member mounted in said door above
the window openings, said rotatable member being rotated
during locking of the door shut on an oven, said linkage
system being connected to said rotatable member whereby such
rotational movement of said rotatable member is translated
by said linkage system into raising said shield to a
position which covers such pane in the outer door panel,
said linkage system including first and second link arms
which are pivotally connected together and which extend as
said shield is raised during the rotational movements of
said rotatable member; said first and second link arms
attaining a dead centre position when they are at their
maximum extension and said shield is raised to its maximum
height in the door, an oven-centre stop means for stopping
movement of said first and second link arms as they pass
their dead centre position thereby preventing continued down-
ward descent of said shield so that the shield is maintained
in a window covering position while the door is locked.


2. In an oven door of claim 1, rotation of said rotatable
member cooperating with a locking movement in a lock means
to lock said door shut on an oven, such locking movement
being activated by an externally operable grasp.




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3. In an oven door of claim 1, said rotatable member
having a locking portion extending outwardly of said inner
door panel and a manually operable grasp extending outwardly
of said outer door panel, said locking portion being adapted
to engage an oven frame and lock said oven door shut on an
oven upon rotation of said rotatable member.


4. In an oven door of claim 2 the unconnected end of said
first link arm being secured to said rotatable means.


5. In an oven door of claim 4, an L-shaped link arm being
pivotally mounted in said door to a side of said window open-
ings, a first leg of which has its end pivotally connected to
said second link arm and a second leg of which has its end
pivotally connected to said shield, said first leg extending
upwardly of said door and said second leg extending across
said door, and guide means for guiding movement of said
shield within said door.


6. In an oven door of claim 5, said guide means comprising
a guide link arm connected to said shield and mounted in said
door beneath said L-shaped arm where its pivot points at
each end in conjunction with the respective pivot points of
said L-shaped link arm define a parallelogram.


7. In an oven door of claim 6, a track system on which
said shield is mounted comprising first and second rods
extending vertically of said door located on each side of the
window, each end of said shield having overturned edges to


14

define channels through which said first and second rods
extend, the overturned edges overlapping said shield suffi-
ciently to preclude disengagement of the shield from the rods
as it is raised and lowered.


8. In an oven door of claim 4, said stop means being
positioned within said door to block further movement of
said first link arm after it passes through the dead centre
position.


9. In an oven door of claim 8, a frame member in which
said rotatable member is mounted having a portion thereof to
one side constituting said stop portion.


10. In a self-cleaning oven with a windowed oven door,
said door including transparent window panes in its outer
and inner door panels, a shield located within the door for
blocking said window panes and shielding the outer trans-
parent pane from thermal radiation generated by said oven
operating at self-cleaning temperatures, a system to which said
shield is mounted being capable of raising and lowering the
shield to and from a window covering position, said system
comprising a rotatable member mounted in said door above said
window openings, the rotation of said rotatable member being
coordinated with a movement which causes locking of the door
shut on said oven, a first link arm secured to said rotatable
member and positioned for movement through a vertical plane
during rotation of said rotatable member, a second link arm
having one end pivotally connected to a free end of said first
link arm and the other end pivotally connected to an end of



an L-shaped link arm, said L-shaped link arm being pivotally
mounted to one side of said window within said door, the other
end of said L-shaped link arm being pivotally connected to said
shield, guide means for guiding movement of said shield, the
arrangement being such that rotational movement of said ro-
tatable member is translated into raising said shield to a
window covering position, said first link arm and said second
link arm being at their maximum extension when the axis of
rotation of said rotatable member, the pivot point between
said first and second link arms and the pivot point between
said second and L-shaped link arms are aligned, a stop means
for interfering with continued movement of said first and second
link arms to stop rotation of said rotatable member after
maximum extension of said first and second link arms, the weight
of said shield maintaining the interference with the movement
of said first and second link arms to thereby retain said shield
in the window covering position.



11. In an oven of claim 10, said first and second link
arms being located above said window at all times during
shield raising, said L-shaped arm having a first leg which
is connected to said second link arm, extending upwardly of
said door alongside the window, a second leg of said L-shaped
arm which is connected to said shield extending across said
door beneath said window when the shield is in its lowered
position, said second leg being pivotally connected to the
top portion of the shield.



12. In an oven of claim 10, said guide means being a

third link arm located below said L-shaped arm and having

16

one end pivotally connected to said shield and the other end
pivotally mounted in said door with the pivot points of said
third arm and corresponding pivot points of said L-shaped arm
defining a parallelogram.



13. In an oven of claim 10, lock actuation means mounted
on the oven frame above said door, movement of said lock
actuation means to a door locking position rotating said
rotatable member by an interengagement between said lock
actuation means and said rotatable member.



14. In an oven of claim 13, said rotatable member having a
lug extending outwardly of said inner door panel, said lug
being received internally of said oven frame through a slot
provided therein, said lock actuation means having a portion
engaging said lug for rotation thereof upon movement of said
lock actuation means to a door locking position.



15. In an oven of claim 14, a handle mounted on said lock
actuation means and being external of said oven and above
said door.



16. In an oven of claim 10, said rotatable member
comprising a lug portion extending outwardly of said inner
door panel, said lug portion being adapted to engage the oven

frame in a manner to lock the door shut on said oven when
said rotatable member is rotated in the proper direction.



17. In an oven of claim 13, said rotatable member having
connected thereto an externally accessible grasp on said
outer door panel.


17

18. In an oven door having spaced apart outer and inner
door panels with aligned window openings and at least one
transparent window pane in each window opening, apparatus
for holding said oven door at and releasing said oven door
from a closed locked position on an oven and for raising and
lowering a shield between said door panels to and from a
position which covers and shields such transparent window
pane in said outer door panel from thermal radiation
generated by an oven operating at high temperatures, said
apparatus comprising rotatable means mounted in said door
panels above said window openings, said rotatable means
having an oven frame engaging portion extending outwardly
from the inner door panel which is adapted to engage and
hold said oven door closed upon rotation of said rotatable
means to a door locked position, said rotatable means having
an arm extending outwardly from said rotatable means between
said door panels, said arm having its free end pivotally
connected to a first end of a link arm extending transversely
of the door above said window opening, a second end of said
link arm being pivotally connected to a device for raising
and lowering said shield, the position of said arm in a door
unlocked position being such that upon rotation of said
rotatable means to a door locked position, said arm and link
arm are extended to and retracted from maximum extension in
a direction transverse of said door where such transverse
movement is translated into raising and lowering said shield
by said device, a stop means for stopping rotation of said
rotatable means at a point where said arm and link arm are
retracting from maximum extension by continued door locking
rotation, said shield in its attempting to continue its


18

downward movement maintains operability of said stop means
to hold said shield in the window covering position while
the oven door is locked shut on an oven.



19. In an oven door of claim 18, said device comprises an
L-shaped arm pivotally mounted on the inner panel of said
door to one side of said window opening, a first arm of
said L-shaped arm extending upwardly alongside the window
opening and having its upper end pivotally connected to said
link arm, a second arm of said L-shaped arm extending
transversely of said door beneath said window when said
shield is in its lowered position, the end of said second
arm being pivotally connected to the upper portion of said
shield, the transverse movement of said link arm pivoting
said L-shaped arm to either raise or lower the shield
depending upon the direction of rotation of said rotatable
means, and guide means provided to guide the movement of
said shield.



20. In an oven door of claim 19, said guide means com-
prising a second link arm pivotally connected to said shield
at one end and at the other end pivotally mounted on said
inner door panel, the respective pivot points of said L-shaped
arm and second link arm being in parallelogram relationship.



21. In an oven door of claim 18, said rotatable means

being mounted in a frame secured to said inner door panel,
a portion of said frame constituting said stop means which
is contacted by said arm.

19

22. An oven door comprising spaced apart outer and inner
door panels with aligned window openings and at least one
transparent window pane in each window opening, a shield
positioned between said outer and inner door panels and
mounted on a transport mechanism for raising and lowering
said shield to and from a position which covers and shields
such transparent window pane in said outer door panel from
thermal radiation generated by an oven, and rotatable means
for locking said oven door shut which upon rotation to a
locking position activates said transport mechanism to raise
said shield to the window covering position, said rotatable
means being mounted in said door panels above said window
openings and having a lock portion extending outwardly from
said inner panel and an arm extending radially from said
rotatable means between said door panels and always remaining
above. said window openings, said lock portion being adapted
to engage a mating lock portion on an oven frame to lock
said oven door shut upon rotation of said rotatable means,
said arm being pivotally connected to an end of a link arm
which extends transversely of said oven door between said
door panels and always above said window openings, the other
end of said link arm being pivotally connected to a part of
said transport means, the arrangement of said arm relative
to said link arm being such that as said rotatable means is
rotated to lock said oven door shut, the distance between the
pivot point at said other end of said link arm and the axis
of rotation of said rotatable means increases and decreases
from a maximum with corresponding transverse movement of said
link arm, such transverse movement being translated into
raising said shield by virtue of said link arm's connection



with a part of said transport mechanism where said shield is
raised to its maximum vertical height when the oven door is
closed on an oven as said distance attains a maximum, stop
means for stopping rotation of said rotatable means at a
position after said maximum distance has been attained and
passed in the direction of rotation to the locking position,
the stop means being positioned to locate said shield over
such window pane and thereby retain said shield in the window
covering position.



23. An oven door of claim 22, said lock portion being a
lug which is adapted to engage an oven frame member to lock
said oven door shut during rotation of said rotatable member.



24. An oven door of claim 22, said transport means
comprising an L-shaped arm, a second link arm, and guide
means for guiding movement of said shield, said L-shaped arm
being pivotally mounted to the inner door panel and to one
side of said window openings, a first arm of said L-shaped
arm extending upwardly alongside said window opening with
its end pivotally connected to said link arm, a second arm of
said L-shaped arm extending across said oven door beneath said
window when the shield is in its lowered position, its end
being pivotally connected to said shield, said second link
arm having one end pivotally connected to said shield beneath
said second arm and having its other end pivotally mounted to
said inner door panel, the pivot points of said second arm and
second link arm being vertically aligned.

21

25. An oven door of claim 24, wherein said guide means
comprises two rods extending upwardly in said door and
positioned to each side of said window openings, each end of
said shield having overturned edges which engage said rods,
the rod located on the side of the window on which said
L-shaped arm is pivoted being shaped to accommodate the
swinging movement of said shield as it is raised, the other
rod being straight where the overturned edge of the shield
sufficiently overlaps the ord to ensure continuous engagement
therewith.


26. An oven door of claim 25, wherein said rods are
covered with a friction reducing material.


27. An oven door of claim 24, wherein the top and bottom
portions of the shield are overturned to provide points of
connection to the shield which are invisible from the front
of the door.


22

Description

~063~67
Field of the Invention
This invention relates to ovens and more particularly
to windowed oven doors for self-cleaning ovens of ranges
and the like.

Background of the Invention
It is customary to provide a window in an oven
door so that baking, broiling and other cooking operations
within an oven can be observed. Ranges equipped with an
oven self-cle,aning cycle raise the temperature of the oven
to temperatures which cause pyrolysis of built-up grease and
grime. This results in raising the external temperatures of
the oven door, and in particular the oven window, to hazardous ~ ~ -
.... .
, levels. Provisions are therefore made to heavily insulate the
standard oven door plug, to improve on cooling ventilation -
` 15 of the door and to protect with a shield the outer transparent -
pane in the window from thermal radiation generated in the
oven operating at the higher self-cleaning temperatures.
i. Due to this vast range of temperatures at which the oven
` operates, the design of the mechanism for raising and
'1! 20 lowering the shield to and from a window covering position
j has to accommodate thermal expansion therein. Some mechanisms
involve very complex linkage systems for raising and lowering
the shield and track systems for the shield which from time
to time become stuck in their operation and are usually noisy
in operation. It is important to provide a lock means on the
oven door to lock the oven door shut to preclude user
injury while the oven is operating at the higher self-cleaning
temperatures. Mechanisms are available on oven doors which
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10~;3467

raise a shield to a window covering position and lock the
oven door shut on an oven. However, such mechanisms are
usually complex in nature and are expensive to manufacture.


This invention provides in a windowed oven door a
system which locks an oven door shut on an oven while raising
a shield within the door to a window covering position in
- an effortless manner involving a small number of parts
with the resultant reduction in manufacturing costs.


Brief Summaryl of the Invention


A windowed oven door according to this invention
for an oven has inner and outer door panels with aligned window
openings, at least one transparent pane being positioned ~ -
in each window opening. A rotatable member is mounted in
, the door above the window openings, the rotation of which
~ 15 is common to the movement of locking the oven door shut on
an oven and the movement of raising and lowering the shield
to a window covering position. The mechanism for raising
! and lowering the shield includes a linkage system where
rotation of the rotatable member is translated by the linkage
system into raising or lowering the shield to or from a
position which blocks the window openings. The linkage
system includes first and second link arms which are pivotally
connected together and which are adapted to extend during the
linkage system's movement for raising the shield. The first -
and second link arms attain a dead center position when at

their maximum extension and the shield is at its maximum ~ -
. height in the door. An overcenter stop means is provided ;~ -
! for stopping movement of the first and second link arms as


l - 2 -

1063467
they pass their dead center position. The overcenter stop
means operates to prevent continued downward descent of the
shield so that the shield is maintained in a position to
block the window openings and to shield the outer transparent
window pane from thermal radiation generated by an oven.
The first and second link arms of the linkage
mechanism may be arranged so as to always be above the window ~
- in the oven door. The first link arm according to an embodi- ;
ment of the invention has an end secured to said rotatable
member and adapted to move through a vertical plane upon
rotation of said rotatable member. The free end of the first
link arm being pivotally connected to the second link arm and
arranged so that the first and second link arms extend in
the desired manner during locking of the oven door to raise
J
the shield to a window covering position.
A guidance means for guiding the movement of the
shield may be provided to further reduce noise in the shield
raising operation. The shield ends are overturned to provide
~` two channels through which rods extend. The rods are mounted
in the door on each side of the window opening. The rods
may be covered with a friction reducing material to further
dampen noise generated by the shield movement. rrhe overlapped
,J ends of the shield provide a simple arrangement for engage-
:,i
ment between the rods and shield.
The rotation of the rotatable member is coordinated -
~, with the motion of locking the oven door shut. Various types

' ~ ~

~ .
~' ~ :
,~ . . . .: ~ . : . -
... . . . .
~ : - -: - . - -

` 1063467
of locking means may be used where, for example, the
rotation of the rotatable member effects locking of the door
or movement of the locking means effects the desired rotation
of the rotatable member.
Description of the drawings
These and other objects, advantages and features
of the invention will become apparent in the following
detailed description of the preferred embodiments of
the invention, as shown in the drawings wherein:
FIGURE 1 is an isometric view of an oven -
having a windowed oven door; -
FIGURE 2 is a sectional view of the windowed oven
door and a portion of the oven frame according to this
` invention;
. 15 FIGURE 3 is a view of the oven door with the
. front panel removed to show the mechanism for raising
and lowering the shield, the shield being in its lowered
position;
- FIGURE 4 is a view of the door panel of Figure 3
with the shield in the raised position;
FIGURE 5 is a view of various positions of parts
of the linkage mechanism during the raising of a shield;
~ FIGURE 6 is a view of the shield; ..
~ FIGURE 7 is a view of a section of oven door ~ :
~. 25 and range body to show an alternative lock actuation
"< .:
~ means which is mounted on the oven frame;
, . . . .
.,

"
,, .

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~ ~ 4 ~ ~ ~:

, . ~ ., . . . , - . .. . - , .. - - . .. - - . . :: - . -


1063467
Detailed Description of the Preferred Embodiments of the
Invention
The range as shown in Figure 1 has a windowed oven
door 10 with window opening 12. The door is mounted on an oven
frame 14 having a cooking top 16 with burner elements 18.
A control panel 20 is provided with control knobs 22 for
controlling functions of the various burner elements 18, the
oven temperatures and the oven self-cleaning cycle. The oven
door 10 has a handle 24 to facilitate its opening and
closing. A conventional pots and pans drawer 26 is provided
at the base of the range.

Turning to the section of the oven door shown in
Figure 2 with the door in the oven closing position, the upper
part of the oven door 10 is beneath the cooking top 16.
The oven frame has a liner portion 28 which defines the
oven cavity and a vertical face plate portion 30 at its front.
The oven door 10 has an outer panel 32 and an inner panel 38.
Each has a window opening 12. The inner panel 38 has a
further panel 36 spaced therefrom and mounted thereto to
form the plug portion 35 of the oven door which projects
within the oven cavity. ;~

The plug portion is well insulated with fire-proof
insulation 34. Panel 36 also has a window opening 12 aligned
with the others. The window openings have transparent panes
40, 42, and 44. Spaced apart panes 40 and 42 form an insulative
barrier in the plug portion. A shield 46 is located in its
lowered position beneath window opening 12 between the inner
and outer door panels. A linkage mechanism generally

.

~ - . , .

~!D63~67
designated at 48 is mounted within the door and is capable
of raising and lowering the shield to and from a position
which blocks the window opening 12 and shields the outer
transparent pane 44 from thermal radiation generated within
the oven operating at self-cleaning temperatures.


A lock mechanism generally designated 50 is provided
in the upper part of the door 10 and in this particular
instance is actuated by an external grasp or knob 52. The
lock mechanism 50 in this preferred embodiment has a lug
portion 60 upstanding from its rotatable shaft 58. The
lug portion 60 is received by a slot 62 in plate 30 of the
oven frame. Rotation of knob 52 places the lug 60 in a
position offset from the slot 62 to lock the door shut by
engagement of lug 60 with the inner surface of plate 30.
Rod 54 has at its end a cup portion 64 which snugly
receives lug 60 to cause rotation in rod 54. At the back
of the range, switches are located and are actuated by rod
rotation. Such switches when actuated serve to start the
self-cleaning cycle if the controls are properly set and
activate a stop to the rotation of rod 54 in an unlocking
direction before lug 60 is aligned with slot 62 while the oven
is operating at self-cleaning temperatures. This prevents
the user from unlocking the oven door and opening ~he oven
when at temperatures in excess of about 500F. A gasket 56
is provided on the inner part of the door to reduce heat
losses from the oven.
Figures 3, 4 and 5 show various positions of the ~-
linkage mechanism in its raising and lowering the shield within
the oven door and the movement of the linkage mechanism when
the shield is at its uppermost and just past dead center



- 6 -

~063467
positions. The inner panel 38 is shown in Figure 3 where
in this embodiment, the linkage mechanism is mounted on such
panel. The rotatable member 58 with the lug portion 60
is mounted in a frame 66 which is in turn fastened to the
inner panel by spotwelds 68. Secured to the rotatable member
58 is a first link or arm 70 which as shown in Figures 2 and
3 extends radially downwardly from the rotatable member
` and swings through a vertical plane with the door in the ver-
tical position. The free end 72 of the arm 70 is pivotally
connected at 74 to a link arm 76. Both these arms are located
above the window opening 12 and may be referred to as first
` and second link arms. Link arm 76 extends somewhat transversely
of the oven door above the window. The other end of link
, arm 76 is pivotally connected at 78 to the device which
in turn is connected to and thereby raises and lowers the ~-
~. shield. In this embodiment of the invention, the device
.
~; comprises an L-shaped link arm 80 which is pivotally mounted

^~ to the inner panel 38 at 82 in the manner shown in Figure 2.

It is understood that some form of guidance means

for shield movement is necessary with this particular embodiment

because of the single pivotal connection of the L-shaped arm to

;3 the shield at 96. However, with other types of linkages, a
.~,
guidance system may not be necessary or the guidance aspect
may be inherent in the arrangement of the linkage system. As -

part of the means for guiding shield movement in this embodi- -~
'- .
ment a third or guide link arm 84 is provided. At one end -

it is pivotally mounted at 86 on the inner door panel.
~,l The other end is pivotally connected at 88 to the lower
~ portion of shield 46. L-shaped link arm 80 has a first
-~ 30 arm 90 extending upwardly and to a side of the window opening
,

.. ~ .

1063467
12 with an inwardly bent portion 92. The second leg 94 of
L-shaped arm 80 extends beneath window opening 12 and is
pivotally connected to the shield at 96. To ensure a smooth
raising of the shield and a swinging arc to its motion,
pivot point pair 82, 86 and pair 88, 96 are vertically
aligned and are always maintained in parallelogram relation-
ship during the raising and lowering of the shield.
To improve on the smoothness in raising and lowering
of the shield in a noiseless manner while the door is in a
`10 vertical position, the guidance system also includes a track
means. The shield has overturned ends 98 and 100 to form
channels 102 and 104 which are more clearly shown in Figure 6.
Rods 106 and 108 are secured at their upper extremities at
110 and 112 and at their lower extremities by location in tabs
' 15 at 114 and 116. The rods 106 and 108 extend through channels
102 and 104 respectively. Due to the parallelogram relation- ~ -
ship of the corresponding pivot points of arms 84 and 80,
the shield 46 is swung upwardly along an arcuate path as
apparent from comparism of shield positions in Figures 3 and 4.
To accommodate this swinging motion, rod 108 is shaped so as -
to not bind against the bottom of overturned end 100.
Rod 106 is straight because overlapped end 98 of shield 46
is moving away from the rod. However, it is important to
ensure that the degree of overlap of portion 98 be
sufficient to maintain engagement of the rod within over-
turned end 98 during the upward and downward movement
of the shield. The upper and lower portions of shield are
~;~ overturned to provide lips 136 and 138 to which the link
arms 80 and 84 are pivotally connected at points 96
and 88. These pivot points are behind the shield so that ~ --
A 8

106~467
the points of connection are invisible to provide a pleasing
appearance from the oven door front.
Rods 106 and 108 may be coated with a friction
reducing material to facilitate the shield's quiet sliding
over the rods. Apertures 118 and 120 are provided on both
sides at the bottom of the inner panel 38 to accommodate
` hinge arms which locate the door on the oven frame.
Figure 4 illustrates the shield 46 in its window
covering posi~ion with the link arms in a new position where
the lug 60 is rotated about the axis of the rotatable member 58
counterclockwise approximately 90 and is therefore out of
alignment with the slot in the oven frame to ensure the
locking of the door shut on the oven. In moving the locking
mechanism 50 to lock the door shut, the first arm 70 as it
is secured to the rotatable member 58 is also swung counter-
clockwise. Due to its pivotal relationship with the second
~ link arm 76 and the second link arms pivotal relationship
`iJ~ with the L-shaped arm, arms 70 and 76 extend resulting in
a transverse motion of pivot point 78 away from the axis of
rotation of member 58. This causes the L-shaped arm to pivot
about point 82 in a clockwise direction thereby raising
! the shield to a window covering position. The geometry
of the link arms is such to translate the approximate 90
~1 rotation of the locking mechanism into a sufficient movement
--' 25 in the linkage system to raise the shield to a window covering
' position.
Turning to Figure 5, as the first and second link
' arms 70 and 76 extend, they-reach maximum extension in positions
~,
~ 70a and 76a. At this point, the axis of rotation 122 of
. . .
~ 30 rotatable member 58, the pivot point 74a and pivot point 78a
-A _ g _

~06346~
are aligned and the distance between axis 122 and pivot
point 78a is at a maximum. This position of the first and
second link arms is therefore referred to as the dead center
position. It is apparent that with the first and second
link arms in the dead centre position the shield 46 is at
its maximum height within the door.
The rotation of the rotatable member 58 is continued
until first link arm 70 attains position 70b where its
recessed portion 124 meets frame 68 to interfere with its
continued movement and thereby constitute an overcentre stop
means. However, with this rotation past dead centre of the
first and second link arms, they retract from their
maximum extension, the distance between pivot point 78b and
axis 122 decreasing. This results in a slight lowering of
the shield, the L-shaped arm moving to position 80b. The
stop or interference between recess 124 and frame member 68
is so arranged that the downward movement of the shield does
' not drop far enough to uncover any portion of the window. Due
to this overcentre stop of the first and second link arms, the
~ 20 weight of the shield maintains the interference between 124
!~ and 68. With this overcentre locking of the shield in the
Y raised position, there is a positive snap action in the rotation
of the rotatable member 58 to indicate to the user that the
shield is in its proper window covering position. Therefore,
with the oven door in the lock position, the shield 46 is - -
retained in a window covering position by the overcentre stop
arrangement so that the range is now ready for the oven self-
cleaning cycle.
- It is appreciated that other forms of stop means may
be employed in providing the overcentre stop for link arms 70

'~ - 10 -

: . - , :. ... :- .. :

106341~7
and 76. Such stop means may include a tab struck from either
first or second link arms 70, /6, which interferes with the
continued movement of either arm at a position which would be
equivalent to the interference between frame 68 and recessed
part 124 of arm 70. It is also apparent that pins or the like
may be substituted for the frame part 68 to constitute a
stop or interference with the continued motion of the first -~
and second link arms past the dead centre position.
As discussed, the rotatable member 58 is common to
both the motion of locking the oven door and raising the shield.
It is apparent that other forms of locking mechanisms may be
employed which on movement to the locking position effect
rotation in rotatable member 58 to cause a raising of the shield.
An alternative form of lock actuation means is illu- -
strated in Figure 7 where a rotatable arm 126 is mounted on the
oven frame upper portion 29 and lS pivoted about connection 128
by grasping knob 130. The arm 126 is provided with a rectangular
slot 132 through which an extension 134 secured to cup 64 extends.
A return spring 136 is provided to maintain lug 60 in position
', 20 for registration with slot 62 when the oven door is closed.
` It is apparent that moving the arm 126 in a clockwise direction
about point 128 causes rotation of the extension 134 about
rotatable arm 58 in a counterclockwise direction to effect
, desired locking of the oven door shut on an oven and at the
j 25 same time effects the desired rotation of rotatable member 58
to raise the shield to the window covering position.
', Other arrangements are possible, such as providing the
rotatable member 58 with an upstanding member internally of
~, the door which is engaged by a locking member provided on the
oven frame such that the locking members movement across the

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IC~6`3467
length of the door causes the desired rotation in the
rotatable member while at the same time effecting a secure
locking of the door on the oven.
After the self-cleaning cycle has been completed and
the oven has cooled down below approximately 500F, the
aforementioned switches release the stop on rod 54 to permit
rotation of the locking means 50 in a direction to unlock the
doo~. It is understood that in carrying out the unlocking
procedure, the linkage mechanism initially raises the shield
until the first and second link arms reach their dead centre
position and then begins lowering the shield as the first
and second link arms pass their dead centre position and
resume positions 70 and 76.
As can be appreciated by those skilled in the art,
,~ 15 this arrangement of linkage system with the overcentre stop
entails the use of a small number of parts thereby reducing
manufacturing costs in providing a mechanism for raising and
~; lowering the shield. Guidance means in the form of a secondary -
., .
link arm 84 and guide rods 106 and 108 to which the shield
is mounted provide for an improved noiseless operation.
;i Although various preferred embodiments of the -
;'~ invention have been described herein in detail, it will be
understood by those skilled in the art that variations may
be made thereto in providing an operative unit which fall
;~ 25 within the spirit of the lnvention and the scope of the
i appended claims.
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