Closure fasteners – Bolts – Hooked end
Reexamination Certificate
2000-08-16
2002-11-05
Knight, Anthony (Department: 3676)
Closure fasteners
Bolts
Hooked end
C292SDIG006, C292SDIG006, C070SDIG001
Reexamination Certificate
active
06474702
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to door locks for ranges and ovens. More specifically, the present invention relates to manual range and oven locks for the doors of self-cleaning ovens.
BACKGROUND
Modern ovens are often equipped with the capability to self-clean. Self-cleaning is accomplished by heating the oven to temperatures of approximately 400-480° C. (750-900° F.). Self-cleaning ovens typically employ a door lock to latch and lock the oven door during the cleaning operation. Existing door locks take various forms, the most advanced of which will automatically lock the door at the beginning of the cleaning operation and automatically unlock the door when the oven reaches a predetermined reduced temperature.
In some self-cleaning ovens, a bimetallic coil, which is responsive to the temperature in the oven, moves a pawl into a blocking position with respect to a latch to prevent the latch from moving from a latched position to an unlatched position after the bimetallic coil senses temperatures above a predetermined level. Such devices are disclosed in U.S. Pat. Nos. 3,438,666; 4,133,337 and 4,838,586.
The bimetallic coil is, of course, sensitive to the heat in the oven, whether it is in a self-cleaning mode or in any heating mode, and will move the blocking pawl towards a blocking position in either mode. It is possible to lock the oven door shut inadvertently during an extended bake cycle. If the oven remains in a bake mode at an elevated temperature for an extended period of time, the locking pawl may move to a position which would block the movement of the handle from the latched position to the unlatched position.
A problem is presented by the possibility that, during an extended baking cycle, the latching handle may be inadvertently moved to the latched position. This may be possible because the latch may be cammed past the locking pawl and the latch will be blocked from unlatching until the oven temperature falls to a level such that the bimetallic element will move the locking pawl away from a block position. This can have deleterious effects on the contents of the oven which are being subjected to baking, in that the oven door cannot be opened at the desired time, and the contents of the oven will continue to bake, perhaps resulting in a burned condition or an overcooked condition.
OBJECTIVES OF THE PRESENT INVENTION
Accordingly, it is an object of the present invention to provide an improved oven door lock which prevents inadvertent oven self-cleaning operation.
It is another objective of this invention to provide an improved oven door lock which is more easily assembled with a cooking apparatus.
It is yet another objective of the present invention to provide a latching mechanism for self-cleaning ovens which can withstand high temperatures.
Yet another objective of the present invention is to provide a latching mechanism which senses whether an oven door is latched and locked to allow self-cleaning operation.
A further objective of the present invention is to provide a latching mechanism with a minimal number of parts for greater reliability and simplified assembly.
SUMMARY OF THE INVENTION
The invention preferably embodies an improved oven door lock for use in a self-cleaning oven having a door moveable between open and closed positions and a device for effecting a heat self-cleaning cycle when the door has been closed and latched. The door lock generally includes a mounting bracket to which a latch mechanism with a moveable latch arm is pivotally mounted and a lock mechanism with a thermally responsive element adapted to lock the latch arm in a latched state during oven self-cleaning.
A link arm is provided to link the latch arm with a handle mount to which a handle is affixed to effect manual operation of the door lock. The mounting bracket and link arm define respective holes which align substantially coaxially with each other when the latch mechanism is moved from the unlatched to the latched state. The thermally responsive element is preferably a bimetallic leaf which has a lock member affixed thereto. When the oven is placed in self-cleaning mode, the bimetallic leaf is heated and deflects so that the lock member is received through the axially aligned holes in the mounting bracket and link arm. When the lock member is received through the holes, the latch mechanism is prevented from being moved from the latched state to the unlatched state during self-cleaning operation. The bimetallic leaf does not need to be calibrated to respond to heating of the oven chamber, unlike thermally responsive elements of the prior art.
The lock mechanism, including the bimetallic leaf and the lock member, is a separable subassembly to the oven door lock. That is, the lock mechanism is detachable from the mounting bracket, thereby providing ease of assembly and maintenance to the oven door lock. In addition, the lock mechanism includes a depending hook which is adapted to engage an oven cavity wall during assembly. Prior art oven door locks have been generally very difficult to assemble with the oven cavity wall and the provision of the hook on the lock mechanism eliminates a significant amount of time and labor expended upon assembly of the oven door lock with the oven. Assembly of the latch mechanism to the mounting bracket is provided upon a single surface of the mounting bracket. That is, the latch mechanism including the latch, the link arm, the handle mount, a handle, and a biasing spring is assembled to one surface of the mounting bracket to provide additional ease of assembly.
The oven door lock includes a switch adapted to indicate whether the latch is in either the unlatched or latched state. The switch is attached to the mounting bracket with an insulation pad sandwiched therebetween to electrically and thermally insulate the switch from the mounting bracket. The insulation pad prevents overheating of the switch and prevents the switch from transferring an electric charge to the mounting bracket and, therefore, the oven to prevent a user from receiving an electric shock.
The latch mechanism includes an improved nuisance latch which prevents the latch mechanism from being moved from the unlatched state to the latched state and, therefore, avoiding locking of the latch mechanism in the latched state, during non-self-cleaning operation of the oven. The nuisance latch includes a thermally responsive element which deflects into engagement with the latch mechanism as the oven is used for cooking. When the thermally responsive element engages the latch mechanism, the holes in the mounting bracket and the link arm are prevented from aligning. Thus, when the lock mechanism bimetallic leaf deflects upwardly in response to heating the oven, the lock member is prevented from locking the latch mechanism in the latched state.
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Livers, Jr. James D.
Malone Charles
Ramsey James
France/Scott Fetzer Company
Knight Anthony
Walsh John B.
Wood Herron & Evans L.L.P.
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