Motorized oven door latch assembly
A compact, reliable motorized oven door latch assembly utilizes a latch that pivotally connects to a motor at an axis that is offset from the motor's axis. The latch includes a latch guide that is guided by a slot in a housing of the assembly. Rotation of the motor moves the latch between open and closed positions. A cam rotationally engages the motor and includes axially disposed cam surfaces that interact with side-by-side switches to sense when the latch is open and closed. The assembly includes a reusable release/service feature that allows the latch to be opened without operation of the motor if the latch becomes stuck in the closed position. The service feature includes a resiliently deformable flange that defines part of the guide surface.
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1. Field of the Invention
This invention relates to latch mechanisms, and particularly relates to motorized latches that are used to lock oven doors shut during high temperature self cleaning operations.
2. Description of Related Art
In self-cleaning ovens, it is advantageous that the oven door be latched against inadvertent opening during such period of time as the oven is at a high temperature. Various types of manual and motorized latches have been proposed for this application, and it is now customary to include some form of thermostatically controlled mechanism to prevent unwanted or inadvertent opening of the door.
Conventional motorized oven door latch mechanisms are often bulky, which makes it difficult to incorporate such mechanisms into oven designs. Conventional latch mechanisms are also frequently mechanically complex, which makes them expensive to manufacture and prone to failure during operation in the extremely hot environment of an oven.
If a motorized oven door latch mechanism breaks while in the closed position (for example, due to motor failure), it is difficult to open the locked oven door to repair the oven door latch mechanism. It is known in the art to provide a single-use release/service feature to allow the latch to be opened. As illustrated in
Accordingly, one aspect of one or more embodiments of this invention provides a simple, cost-effective, reliable, compact motorized oven door latch mechanism.
Another aspect of one or more embodiments of this invention provides a motorized oven door latch mechanism with a reusable release/service feature that allows an operator to open an oven door that is locked closed without breaking the oven door latch mechanism.
Another aspect of one or more embodiments of this invention provides an oven door latch assembly for locking an oven door in a closed position. The assembly includes a housing and a motor mounted to the housing. The motor includes an output shaft that defines a motor axis. The assembly also includes an oven door latch pivotally connected to the output shaft at a latch axis that is offset from the motor axis. The latch is pivotable relative to the output shaft about the latch axis. Rotational movement of the output shaft moves the oven door latch between open and closed positions.
According to a further aspect of one or more of these embodiments, the assembly also includes a cam mounted to the output shaft to rotate with the output shaft about the motor axis. The cam has a first cam surface that faces a direction parallel to the motor axis. The assembly also includes a first switch disposed on the housing and positioned to be actuated by the first cam surface.
According to a further aspect of one or more of these embodiments, the oven door latch pivotally connects to the output shaft via a pivotal connection between the cam and oven door latch.
According to a further aspect of one or more of these embodiments, the cam includes a second cam surface that faces a direction parallel to the motor axis. The assembly further includes a second switch disposed on the housing and positioned to be actuated by the second cam surface. The first cam surface may be disposed farther from the motor axis than the second cam surface. The first cam surface and first switch may be positioned such that the first cam surface actuates the first switch when the oven door latch is in the closed position. The second cam surface and second switch may be positioned such that the second cam surface actuates the second switch when the oven door latch is in the open position.
According to a further aspect of one or more of these embodiments, the assembly also includes a guide surface disposed on one of the housing and the oven door latch, and a latch guide disposed on the other of the housing and the oven door latch. Abutting contact between the latch guide and guide surface guides the oven door latch as it moves between the open and closed positions. The guide surface may be disposed on the housing and the latch guide may be disposed on the oven door latch.
The latch guide and oven door latch may be integrally formed. The latch guide may be stamped into, molded with, or cast with the oven door latch.
According to a further aspect of one or more of these embodiments, the guide surface is defined by a slot in the housing.
According to a further aspect of one or more of these embodiments, the assembly also includes an elastically deformable element that defines a portion of the guide surface, wherein the elastically deformable element is elastically deformable in a direction that allows the oven door latch to move from the closed position into the open position without rotation of the output shaft.
According to a further aspect of one or more of these embodiments, the assembly is incorporated into an oven. The oven has an oven door with open and closed positions. The assembly locks the oven door closed when the oven door is closed and the latch moves from its open to its closed position. The latch permits the oven door to be opened when the latch is in its open position.
According to a further aspect of one or more of these embodiments, the assembly includes a flange disposed on the housing. The flange defines a portion of the guide surface. The flange is elastically deformable in a direction that allows the oven door latch to move from the closed position into the open position without rotation of the output shaft.
Another aspect of one or more embodiments of the present invention provides a method of making an oven door latch assembly for locking an oven door in a closed position. The method includes mounting a motor to a housing. The motor includes an output shaft that defines a motor axis. The method also includes providing a guide surface on the housing and integrally forming a latch guide with an oven door latch. The method also includes pivotally connecting the oven door latch to the output shaft at a latch axis that is offset from the motor axis. The pivotal connection allows the latch to pivot relative to the output shaft about the latch axis. Rotational movement of the output shaft moves the oven door latch between open and closed positions. The cam track has a guide surface. The latch guide abuts and is guided by the guide surface as the oven door latch moves between the open and closed positions. According to a further aspect of one of these embodiments, integrally forming the latch guide with the oven door latch includes stamping the latch guide into the oven door latch.
Additional and/or alternative advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, disclose preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGSReferring now to the drawings which from a part of this original disclosure:
The motor 30 is an A/C synchronous motor, but may alternatively comprise any other suitable motor (e.g., D/C motor, hydraulic motor, etc.). The motor 30 preferably has enough torque that an additional gear train is not required to drive the assembly 10. Omission of such a conventional gear train, such as that disclosed in U.S. Pat. No. 5,220,153, enables the assembly 10 to be smaller, cheaper, and more reliable than conventional latch mechanisms.
As shown in
As shown in
Pivotally connecting the latch 50 to the output shaft 100 (either directly or indirectly through the cam 40) eliminates the need for an intermediary connecting rod, such as those shown in U.S. Pat. Nos. 6,302,098 and 6,315,336.
As shown in
As shown in
While the illustrated curved cam surface 220 is disposed on the housing 20 and the latch guide 200 is disposed on the latch 50, the curved cam surface 220 may alternatively be defined by a slot in the latch 50 and the latch guide 200 may be disposed on the housing 20 without deviating from the scope of the present invention.
Rotational movement of the motor 30 moves the latch 50 between an open position (see
As shown in
To use the release feature, a service person uses a tool 265 such as that illustrated in
The open position illustrated in
Deformation of the flange 260 in one embodiment requires at least 10 pounds of force and in another embodiment requires about 20 pounds of force so that the latch 50 does not accidentally deform the flange 260 and move into the open position.
The deformation of the flange 260 is elastic such that when the latch 50 is released after opening the oven door 240, the flange 260 returns to its original shape and position (shown in solid lines in
The assembly 10 includes sensors that determine whether the latch 50 is open or closed. As shown in
The outer cam surface 410 and outer switch 70 are disposed an equal distance from the motor axis 120 so that the cam surface 410 actuates the switch 70 when the cam surface 410 passes the switch 70, which occurs when the latch 50 is in the closed position. Consequently, actuation of the switch 70 indicates to the oven that the latch 50 is closed so that the oven can safely initiate a self-cleaning cycle. Conversely, actuation of the switch 60 indicates to the oven that the latch 50 is in the open position, that the oven door could be opened, and that self-cleaning should not be initiated or should be halted.
The cam surface 410 and switch 70 are disposed farther from the motor axis 120 than the cam surface 400 and switch 60 so that the inner cam surface 400 does not actuate the outer switch 70 and the outer cam surface 410 does not actuate the inner switch 60. Alternatively, all four switches 60, 70, and cam surfaces 400, 410 could be disposed an equal distance from the motor axis 120. In such an embodiment, the cam surfaces could extend to different vertical positions to selectively actuate vertically offset switches.
Positioning the cam surfaces 400, 410 on the upper axial end of the cam 40 allows the switches 60, 70 to be mounted to the housing 20 in a compact position, which is closer to the motor 30 than is possible in conventional latch sensors that rely on circumferentially disposed cam surfaces (e.g., U.S. Pat. Nos. 5,220,153 and 6,315,336).
While two switches 60, 70 and two cam surfaces 400, 410 are illustrated, a single cam surface and switch could alternatively be used. The cam surface and switch could be sized and positioned such that the switch is actuated when the latch 50 is closed and released when the latch 50 is open, or vice-versa. Alternatively, a single cam surface could actuate two switches that are appropriately circumferentially spaced around the motor to indicate that the latch 50 is open or closed. Moreover, the switches 60, 70 and cam surfaces 400, 410 may be replaced by any other suitable sensor mechanism that is capable of detecting whether the latch is open or closed without deviating from the scope of the present invention.
The foregoing description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. To the contrary, those skilled in the art should appreciate that varieties may be constructed and employed without departing from the scope of the invention, aspects of which are recited by the claims appended hereto.
Claims
1. An oven door latch assembly for locking an oven door in a closed position, the assembly comprising:
- a housing;
- a motor mounted to the housing, the motor including an output shaft that defines a motor axis; and
- an oven door latch pivotally connected to the output shaft at a latch axis that is offset from the motor axis, the latch being pivotable relative to the output shaft about the latch axis, wherein rotational movement of the output shaft moves the oven door latch between open and closed positions.
2. The oven door latch assembly of claim 1, further comprising:
- a cam mounted to the output shaft to rotate with the output shaft about the motor axis, the cam having a first cam surface that faces a direction parallel to the motor axis; and
- a first switch disposed on the housing and positioned to be actuated by the first cam surface.
3. The oven door latch assembly of claim 2, wherein the oven door latch pivotally connects to the output shaft via a pivotal connection between the cam and oven door latch.
4. The oven door latch assembly of claim 2, wherein the cam further comprises a second cam surface that faces a direction parallel to the motor axis, and wherein the assembly further comprises a second switch disposed on the housing and positioned to be actuated by the second cam surface.
5. The oven door latch assembly of claim 4, wherein the first cam surface is disposed farther from the motor axis than the second cam surface.
6. The oven door latch assembly of claim 4, wherein the first cam surface and first switch are positioned such that the first cam surface actuates the first switch when the oven door latch is in the closed position.
7. The oven door latch assembly of claim 6, wherein the second cam surface and second switch are positioned such that the second cam surface actuates the second switch when the oven door latch is in the open position.
8. The oven door latch assembly of claim 2, further comprising:
- a guide surface disposed on one of the housing and the oven door latch; and
- a latch guide disposed on the other of the housing and the oven door latch,
- wherein abutting contact between the latch guide and guide surface guides the oven door latch as it moves between the open and closed positions.
9. The oven door latch assembly of claim 8, wherein the guide surface is disposed on the housing and the latch guide is disposed on the oven door latch.
10. The oven door latch assembly of claim 9, wherein the latch guide and oven door latch are integrally formed.
11. The oven door latch assembly of claim 9, wherein the guide surface is defined by a slot in the housing.
12. The oven door latch assembly of claim 8, further comprising a deformable element that defines a portion of the guide surface, wherein the deformable element is deformable in a direction that allows the oven door latch to move from the closed position into the open position without rotation of the output shaft.
13. The oven door latch assembly of claim 2, in combination with an oven comprising an oven door having open and closed positions, wherein the assembly locks the oven door closed when the oven door is closed and the latch moves from its open to its closed position, and wherein the latch permits the oven door to be opened when the latch is in its open position.
14. A method of making an oven door latch assembly for locking an oven door in a closed position, the method comprising:
- mounting a motor to a housing, wherein the motor includes an output shaft that defines a motor axis;
- providing a guide surface on the housing,
- integrally forming a latch guide with an oven door latch; and
- pivotally connecting the oven door latch to the output shaft at a latch axis that is offset from the motor axis, wherein the pivotal connection allows the latch to pivot relative to the output shaft about the latch axis, wherein rotational movement of the output shaft moves the oven door latch between open and closed positions, wherein the cam track has a guide surface, and wherein the latch guide abuts and is guided by the guide surface as the oven door latch moves between the open and closed positions.
15. The method of claim 14, wherein integrally forming the latch guide with the oven door latch comprises stamping the latch guide into the oven door latch.
16. An oven door latch assembly for locking an oven door in a closed position, the assembly comprising:
- a housing;
- a motor carried by the housing, the motor including an output shaft that defines a motor axis;
- an oven door latch pivotally connected to the output shaft at a latch axis that is offset from the motor axis, the pivotal connection allowing the latch to pivot relative to the output shaft about the latch axis, wherein rotational movement of the output shaft moves the oven door latch between open and closed positions;
- a latch guide integrally formed with the oven door latch; and
- a cam track disposed on the housing and having a guide surface,
- wherein the latch guide abuts and is guided by the guide surface as the oven door latch moves between the open and closed positions.
17. The oven door latch assembly of claim 16, wherein the cam track and guide surface are defined by a slot in the housing.
18. The oven door latch assembly of claim 16, wherein the latch guide is stamped into the oven door latch.
19. The oven door latch assembly of claim 16, wherein the latch guide is one of stamped into, molded with, or cast with the oven door latch.
20. The oven door latch assembly of claim 16, in combination with an oven comprising an oven door having open and closed positions, wherein the assembly locks the oven door closed when the oven door is closed and the latch moves from its open to its closed position, and wherein the latch permits the oven door to be opened when the latch is in its open position.
Type: Application
Filed: Oct 29, 2004
Publication Date: May 4, 2006
Applicant: THE STANLEY WORKS (New Britain, CT)
Inventors: William Priest (West Harford, CT), Peta-Gaye Whitbourne (Avon, CT), Robert Castrogiovanni (Bristol, CT)
Application Number: 10/976,362
International Classification: F24C 15/04 (20060101);