Closure fasteners – Bolts – Swinging
Reexamination Certificate
2000-05-30
2001-11-13
Oberleitner, Robert J. (Department: 3613)
Closure fasteners
Bolts
Swinging
C292SDIG006
Reexamination Certificate
active
06315336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to oven latches used to latch an oven door closed during a self-cleaning cycle. More specifically, the present invention relates to motorized self-cleaning oven latches used with electronic oven controls.
2. Description of Related Art
Self-cleaning ovens reach a very high temperature during the cleaning operation. To prevent injury, safety standards require the door to be automatically latched when the oven is above a safe operating temperature to prevent the door from being opened. In some ovens, the automatic latching is achieved by moving a locking element with a bimetallic coil responsive to the temperature reached by an oven during the self-cleaning cycle. However, many modern ovens use digital electronic controls and in these designs the latching is preferably accomplished with a motorized latch that operates directly under electronic control.
One problem with conventional motorized latches is that the motor may fail, leaving the door locked even after the temperature within the oven has dropped to a safe level. Failure of the motor when the latch is in the locked position leaves the oven unusable, even when it is not in the self-cleaning cycle. It is essential to provide some means of allowing a service person to open the oven door in the event the motor fails.
Another problem with prior art latches is that the switches or motor may fail when exposed to excessive heat. A further problem is the number of components and the time required to assemble prior art self-cleaning oven latches. Still another problem is that prior art oven latches often require a separate door switch to signal the oven control when the door is closed so that the motorized latch may be operated.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a motorized oven latch that allows a service person to open the oven door in the event the motor fails.
It is another object of the present invention to provide a motorized oven latch having a simple design with a minimum number of parts to decrease manufacturing cost and assembly time.
A further object of the invention is to provide a motorized oven latch design with common components that may be used in different configurations for use with different ovens having varying door designs.
Yet another object of the invention is to provide a motorized oven latch design with an integrated door sensing switch to signal when the door is closed.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
SUMMARY OF THE INVENTION
The above and other objects, which will be apparent to those skilled in art, are achieved in the present invention which is directed to an oven latch having a base, a pivot mounted on the base, a latch arm, a motor, a cam rotatably driven by the motor from a first position to a second position, and a rod connected to the cam and the latch arm. The latch arm has a slot formed in it, and the slot engages the pivot so that the latch arm is free to both slide and rotate relative to the pivot. The rod slides and rotates the latch arm from an open position to a closed position as the cam rotates from the first position to the second position.
In the preferred design the oven latch also includes a guide slot, preferably formed approximately as a “J.” One end of the latch arm is guided by the guide slot to control sliding and rotating motion of the latch arm relative to the pivot. In the most highly preferred embodiment of the invention, the guide slot has a normal guide portion and a repair guide portion.
The latch arm is guided by the normal guide portion of the guide slot during normal operation as the latch arm is moved by the cam and rod between the open position with the cam in the first position and the closed position with the cam in the second position. The latch arm is guided by the repair guide portion when it is necessary to repair the oven latch. The repair guide portion permits the oven latch to be opened when the cam is in the second position.
In one embodiment of the invention, the repair guide portion of the guide slot is separated from the normal guide portion of the guide slot by a mechanical obstruction, preferably a bendable mechanical obstruction, that limits motion of the end of the latch arm to motion along the normal guide portion of the guide slot during normal operation.
In another embodiment of the invention, the repair guide portion of the guide slot is not separated from the normal guide portion of the guide slot. Instead, a spring is connected to the latch arm or the rod to keep the end of the latch arm guided by the normal guide portion of the guide slot during normal operation of the oven latch. The spring allows the end of the latch arm and the rod to be manipulated and guided by the repair guide portion of the guide slot during repair of the oven latch to permit the oven latch to be opened when the cam is in the second position.
The spring may be combined with a guide slot having a widened portion; and an oven door sensing switch having an actuator extending partially across the widened portion of the guide slot to detect the absence of an oven door.
One or more switches may also be installed and operated by the cam as the cam rotates to signal the status of the latch to the oven control.
In yet another embodiment of the oven latch, the base includes first and second halves which may be part of a single extended piece, or which may be physically separate. The first half of the base is mountable near the door of the oven to be latched and the latch arm and the pivot are mounted on that half. The second half of the base has the motor and cam mounted thereon and is mountable in a remote location. The rod is lengthened as necessary to extend between the first and second halves of the base.
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DeLio & Peterson LLC
Oberleitner Robert J.
Pezzlo Benjamin A
Summit Manufacturing, Inc.
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