Springless oven door latch assembly

A springless motorized door latch assembly for locking an oven door in a locked and sealed position for purposes of cleaning the oven. A motor and cam cause a latch member to move between three different positions. In one position the latch member prevents the oven door from opening. From this position, the latch member is pulled inwardly so the oven door is in a locked and sealed position. In its locked and sealed position the door may not be opened.

FIELD OF THE INVENTION

This application relates to a motorized oven door latch assembly for locking an oven door in a closed position when the oven is in a self-cleaning mode.

BACKGROUND OF THE INVENTION

Self-cleaning ovens which are incorporated into self-standing ranges are well known. Such ovens conventionally have an oven door which is hingedly secured to a range body. The oven door may be opened to gain access to an oven cavity. The oven door may also be closed to close the opening for cooking objects placed in the cavity or cleaning the cavity. One or more heating elements reside in the oven cavity for cooking purposes.

Motorized latches which are used to lock oven doors in a closed position so that the oven cavity may be self cleaned are well known.

Assignee's U.S. Pat. Nos. 6,302,098 and 6,698,418 each disclose a motorized oven door latch assembly for locking an oven door in a locked and sealed position for purposes of cleaning the oven. Such oven door latches are activated by a rotary motor located remotely from the latch member above the oven cavity. Activation of the motor causes a rod to translate which causes a latch member secured to the front of the rod to engage the oven door so that the oven door may not be opened. After the cleaning has occurred, the motor is reactivated, causing the latch member at the front of the rod to disengage the oven door so that the oven door may be opened.

Each of these motorized oven door latch assemblies utilizes a spring mechanism to bias the latch member into engagement with the oven door. The spring is typically secured at one end to a mounting plate secured to the range and is secured at the other end to the movable latch member. With repeated use, the spring may wear down and may eventually fail to function properly if subject to enough use.

Motorized range lock assemblies such as the one disclosed in U.S. Pat. No. 6,315,336 have been manufactured and sold without such a spring. One disadvantage with motorized oven door latch assemblies having no spring is that the latch member moves between two positions rather than three. In other words, existing range lock assemblies without springs do not provide what is known in the industry as a “pull in” feature. The pull in feature enables the oven door to move to a locked and sealed position when the latch member is in its third position. When the latch member is in this third pulled in position, the motorized range lock assembly causes the oven door to exert pressure on a gasket sandwiched between the front wall of the range and the oven door.

Therefore, a need exists for a motorized oven door latch assembly which provides the pull in feature without the use of a spring.

SUMMARY OF THE INVENTION

The invention which accomplishes these objectives comprises a motorized door latch assembly for locking an oven door in a closed and sealed position so as to close an oven cavity for purposes of cleaning the oven cavity. The oven door is hingedly mounted on a range body and moveable between an open position, a closed position and a closed and sealed position.

The door latch assembly comprises a mounting plate supported by the range body above the oven cavity and extending generally horizontally. The mounting plate has a guide therethrough proximate the front of the mounting plate. The mounting plate also has a pair of mounting tabs extending upwardly from the body of the mounting plate. The mounting tabs have holes therein to receive fasteners for purposes of mounting the motor above the mounting plate in a location in which the motor does not overheat.

Fixedly secured to the mounting tabs of the mounting plate is a driver such as a motor assembly including a motor and a drive spline. The motor may be fixedly or removably secured to the mounting tabs of the mounting plate or any other portion of the mounting plate at any desired location. The motor rotates a drive spline which extends downwardly from the motor and is engaged with a spline hole formed in a cam, operatively associated with the motor. Thus rotation of the drive spline by the motor assembly causes the cam to rotate.

The cam is sandwiched between the latch member and the motor. The underside of the cam has a contact portion which contacts flanges of the latch member to move the latch member to its desired position upon rotation of the cam.

A latch plate or latch member, having a hook at one end for engaging the oven door, is moved between three positions by rotation of the cam. The latch member is movable between a first position in which the oven door may be opened; a second position in which the oven door may not be opened and a third position in which the oven door is in a locked and sealed position.

The latch member has a pair of spaced parallel upwardly extending flanges at the rear end of the latch member. Rotation of the cam causes a portion of the cam to engage or contact the flanges of the latch member to move the latch member between the three positions.

One of the latch member and mounting plate has a pin and the other of the latch member and mounting plate has a guide in which the pin moves. The size and configuration of the guide and location of the pin restrict the movement of the latch member so as to move the latch member between the three desired positions.

One or more switches may be secured to the mounting plate and operated by rotation of the cam. Contact between the cam and the switches signals a controller which controls operation of the motor.

In operation, rotation of the cam by activation of the motor causes the latch member to move between the three positions. In the first position, the latch member is located such that the oven door may be opened and closed. Upon further rotation of the cam, the latch member moves to a second position in which the hook of the latch member engages the oven door to prevent the oven door from being opened and closed. In the third position, the latch member is pulled inwardly by the cam, pulling the oven door into a locked and sealed position.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, and particularly toFIG. 1, there is illustrated a self-standing range10including a pyrolytic self-cleaning oven12on top of which are a plurality of burners14as is conventional. The range10comprises a range body16having a pair of side walls18, a front wall19, a back wall20(seeFIG. 1) and a top21. Spaced a fixed distance below the top21of the range body16is an oven top wall22. An oven cavity24inside which resides one or more heating elements (not shown) is defined by the oven top wall22, side walls18of the range body, a cavity back wall (not shown) and a bottom27. An oven door26having a handle28and a window30is hingedly mounted to the front wall19of the range body so that a user pulling on the handle28will cause the oven door26to hingedly open about an horizontal axis32in order to move the door26between a closed position as shown inFIG. 1and an open position.

As best illustrated inFIGS. 4–8, the oven door26has a thickness T defined between a back wall34and a front wall36between which is insulation38. The back wall34has an opening39formed therein.

Illustrated within range10above top wall22and below top21of the range body16, is a motorized door latch assembly40mounted to the range body16and/or the range walls21and22, and positioned to latch door26in a closed and sealed position by the action of the front hook90of a latch member42. Further detail on the structure of motorized door latch assembly40and the interaction of latch member42with oven door26is provided below.

As best illustrated inFIG. 2, the door latch assembly40functions to lock the oven door26in a closed and sealed position so that the oven door26may not be opened e.g. when the oven is in a self-cleaning mode. The motorized door latch assembly40comprises multiple components which work together to move a latch member42, best illustrated inFIG. 2, between three different positions so that the oven door26may be opened when the latch member42is in a first position and the oven door26may not be opened when the latch member42is in either its second or third position.

The door latch assembly40comprises a motor assembly43including a motor44activated by power lines45. One type of motor which has proven satisfactory is manufactured by assignee and operates at 120 volts AC; 60 Hz having a speed of 2 rpm. The motor assembly43further includes a drive spline46extending downwardly from a motor housing48.

A cam50is operatively coupled to the motor assembly43. The cam50has a spline hole52configured and adapted to receive and retain the drive spline46of the motor44such that rotation of the drive spline46of the motor44causes the cam50to rotate about a vertical axis53. SeeFIG. 2.

As seen inFIG. 9, the cam50has an upper portion54having a peripheral edge56. An indent58is formed in the upper portion54and extends inwardly from the peripheral edge56of the upper portion54to activate the switches in a manner described below. Below the upper portion54of the cam50is a contact portion60having a peripheral edge61. The peripheral edge61contacts the flanges98of the latch member42in a manner described below. SeeFIG. 2. Below the contact portion60of the cam50is a spline portion62. The spline hole52extends through the entire cam50including the spline portion62, the contact portion60and the upper portion54.

Referring again toFIG. 2, a generally rectangular mounting plate64is secured to range10in any desired manner. The mounting plate64has a generally planar body65, a front lip66extending upwardly from the front of the body65along with two side lips67extending upwardly from the sides of the body65. The front lip66preferably is secured the front wall19of the range10with fasteners (not shown) extending through holes68in the front lip66of the mounting plate64. Preferably, the mounting plate64is located below the top21of the range and above the top wall22of the oven cavity. As best seen inFIG. 3, the front lip66of the mounting plate64has a generally rectangular opening70through which the latch member42passes. Although the drawings illustrate one configuration of mounting plate64located in a particular orientation, the mounting plate64may be secured to the range in other locations or be other configurations without departing from the spirit of the invention.

As best illustrated inFIG. 3, an opening or guide72is located through the body65of the mounting plate64. The guide72is an opening of a particular configuration illustrated in detail inFIG. 3comprising a generally linear shaped rear portion72aand a generally linear shaped front portion72bhaving a stopping surface73. The front and rear portions72b,72aof the guide72form an obtuse angle therebetween giving the guide72a generally L-shaped configuration. The size and configuration of the guide72limits the movement of the latch member42in a manner described in more detail below.

As illustrated inFIG. 2, the body65of the mounting plate64also has a circular hole74therethrough which is sized and adapted to receive the spline portion62of the cam50.

The mounting plate64also has a pair of mounting tabs76integrally formed from the body65of the mounting plate64and extending upwardly from the body65of the mounting plate64. Each of the mounting tabs76has a generally vertical first portion78and a generally horizontal second portion80having a threaded hole82therethrough adapted to receive a fastener84passing through holes86in flanges88in the motor housing48. As seen inFIG. 2, the mounting tabs76enable the motor44to be mounted above the body65of the mounting plate64in a location in which the cam50may be sandwiched between the latch member42and the motor housing48. Furthermore, the mounting tabs76enable the motor44to be mounted above the oven top wall so the motor44does not overheat.

Another component of the motorized door latch assembly40is the latch member42best illustrated inFIG. 2. The latch member42has a hook90located at a front end92and an oval shaped opening94formed through the latch member42proximate a rear or back end96of the latch member42. Between the front and back ends92,96of the latch member42the oval shaped opening94of the latch member42is adapted to receive the spline portion62of the cam50.

As best illustrated inFIG. 2, a pair of spaced, parallel upwardly extending flanges98at the rear end96of the latch member42are located to contact the peripheral edge61of the contact portion60of the cam50as the cam50rotates.

Referring toFIG. 2, a pin100is secured to the latch member42in hole101of the latch member42and extends downwardly therefrom in a fixed location. The pin100remains inside the guide72formed in the body65of the mounting plate64as the latch member42moves between positions. Alternatively, the pin100may be secured to the mounting plate64and the guide formed in the latch member42to restrict movement of the latch member42as the latch member42moves between positions.

As best illustrated inFIGS. 4–8, the latch member42is movable between three positions: a first position illustrated inFIGS. 4 and 6, a second position illustrated inFIG. 7and in dashed lines inFIG. 5and a third position illustrated inFIGS. 5 and 8(in which the door is locked and sealed). In the first position, the hook90of the latch member42is aligned with and may pass through an opening39in the back wall34of the oven door26(seeFIGS. 4 and 6). With the latch member42in this first position, the oven door26may be freely opened and closed, the hook90of the latch member42passing through the opening39in the oven door26. As the cam50rotates due to activation of the motor44, the latch member42moves to its second position, which is shown in dashed lines inFIG. 5and inFIG. 8. When the latch member42is in this second position, the oven door26may not be opened because the hook90of the latch member42catches the back wall34of the oven door26. Upon further rotation of the cam50, the latch member42is pulled rearwardly in the direction of arrow102to its third position (illustrated in solid lines inFIG. 5and inFIG. 8) in which the oven door26is locked and sealed. In this position, the oven door26is correctly sealed and seated so as to provide a tight seal for the oven cleaning process.

As best illustrated inFIG. 2, the motorized door latch assembly40further comprises a pair of switches104secured to the mounting plate64with fasteners106. One type of switch which has proven satisfactory is manufactured by Toneluck and sold as part number L62BJ. Such a switch is SPST Normally Closed, rated at 5 Amp at 120/240 volts AC. However, any other switch may be used in accordance with this invention. The indent58on the periphery56of the upper portion54of the cam50alternatively operates the switches104as it passes the switches104. As shown inFIG. 3, wires105connected to the switches104communicate with a controller (not shown) to let the controller (not shown) know the position of the cam50and also the position of the latch member42.

In operation, upon activation of the motor44, the cam50rotates, causing the latch member42to move from its first position shown inFIGS. 4 and 6to its second position in which the oven door26is prevented from opening (SeeFIGS. 5 AND 7). Upon further rotation of the cam50, the latch member42is pulled rearwardly from its second position to its third position in the direction of arrow102. When the latch member42is in its third position the oven door26is in a locked and sealed position with the back wall34of the oven door26exerting pressure against a gasket108located between the oven door26and the front wall19of the range body.

While we have described one preferred embodiment of the present invention, persons skilled in the art will appreciate changes and modifications which may be made to the present invention without departing from the scope of the invention. Therefore, we do not intend to be limited except by the scope of the following claims.