The present invention relates to an appliance latch and in particular to a latch assembly retaining door closure in the event of a fire in the dryer.
Clothes dryers may employ a rotating perforated drum into which clothes are placed and tumbled within circulation of heated air to dry the clothes. The drum may be accessible for loading and removing clothing through an opening in the front of the dryer cabinet that may be covered by a hinged door when the dryer is in use. Typically, the door is held closed by a spring latch that retains the door closed against the light force of tumbling clothing but that may be readily opened at any time by a higher force applied to the dryer door handle by the user.
In some situations, it may be desirable to provide a latch that will maintain the door in the closed position under elevated temperatures that may melt plastic components. In this way, in the event of a fire in the interior of the dryer, the door will remain closed confining the fire to the interior.
One such latch is described in US patent application 2009/0260198, assigned to the assignee of the present invention and hereby incorporated by reference, which discloses a strike having a bulbous tip that may be received between plastic jaws of a spring clip. The plastic jaws are biased by a metallic U-shaped spring having arms that open by deflecting or pivoting about an axis generally perpendicular to the motion of the strike. The arms of a metallic spring pass through the plastic jaws so that should the plastic jaws melt, the ends of the arms are nevertheless close enough to the strike to grip and retain the strike when the plastic jaws are gone. The plastic jaws, during normal operation, reduce the friction of engagement and disengagement of the latch with the strike.
A U-shaped spring holding the plastic jaws is attached at its base to a metal U-shaped bracket surrounding the U-shaped spring having legs extending forward to attach to the housing of the dryer behind an opening through which the strike would make pass. This metal U-shaped bracket holds the U-shaped spring in proper position even in the event of a fire.
The present invention provides a latch for a clothes dryers or the like in which the U-shaped spring of the prior art is rotated by 90 degrees so that the arms of the U-shaped spring clip pivot about axes generally parallel to the motion of the strike and the arms of the U-shaped spring clip extend across the strike and the opening. This configuration permits elimination of the U-shaped bracket permitting instead a simple plastic support because the U-shaped spring clip has an orientation that may retain itself on the strike and block retraction of the strike even in the absence of the support bracket. This orientation further permits greater flexibility in controlling the spring clip force constant in a shallow form factor. Finally, this orientation permits locking of the strike to be simply accomplished by collaring the ends of the U-shaped spring clip, these ends being displaced from and thus free from interference with the strike itself.
Specifically the present invention provides a latch strike retention assembly adapted to accept and retain a latch strike and including a substantially “U” shaped spring having opposing and substantially parallel arm portions extending from a common base portion. A support bracket holds the U-shaped spring behind an opening through which the strike must pass so that the arm portions of the U-shaped spring extend generally perpendicular to a direction of strike engagement with the arm portions, and the arm portions may flexibly separate within a plane perpendicular to the direction of latch engagement to receive and restrain the strike therebetween.
It is thus a feature of at least one embodiment of the invention to provide a latch with a shallow form factor. It is a further feature of this embodiment to permit use of a simple support bracket which may be in its simplest form a thin plate which does not require high-strength materials for proper support of the U-shaped spring.
The support bracket may be a thermoplastic material.
It is thus a feature of at least one embodiment of the invention to provide a design permitting a readily manufacturable injection molded support bracket while still ensuring that the door will remain latched at elevated temperatures that might melt or burn plastic. By sizing the U-shaped spring to be larger than the aperture and orienting the U-shaped spring across the aperture, retention of the strike may be maintained even without the support bracket.
The support bracket may include apertures receiving arm portions of the U-shaped spring when the arm portions are inserted into the apertures along the plane and may include a snap element capturing the based portion of the U-shaped spring against extraction from the apertures along the plane after insertion of the arm portions into the apertures past the snap element.
It is thus a feature of at least one embodiment of the invention to retain the elements of the latch together for easy manufacture while permitting necessary motion of the U-shaped spring.
The U-shaped spring is a single rod of substantially circular cross-section.
It is thus a feature of at least one embodiment of the invention to provide an extremely simple wire-form latch element whose orientation permits the necessary flexibility to be obtained in an arbitrary wire size. It is another feature of at least one embodiment of the invention to provide an outer surface of the U-shaped spring conducive to smooth engagement with a tapered strike.
The arm portions of the U-shaped spring distal to a point of engagement with the strike may have an un-flexed separation smaller than a corresponding thickness of the strike between the arm portions when the strike is engaged with the U-shaped spring, and/or the arm portions of the U-shaped spring at a point of engagement with the strike may have an un-flexed separation smaller than a corresponding thickness of the strike at the point of engagement.
It is thus a feature of at least one embodiment of the invention to ensure that the U-shaped spring is retained on the strike even in the absence of the support plate.
The U-shaped spring may extend at least three times the width of the base portion measured perpendicularly to the extent of the arm portions.
It is thus a feature of at least one embodiment of the invention to provide a substantially parallel separation of the arm portions of the U-shaped spring for robust engagement with the strike. It is another feature of at least one embodiment of the invention to permit engagement of the strike at a variety of positions along the U-shaped spring to accommodate vertical strike movement resulting from manufacturing tolerances and/or door hinge sag.
The latch strike may further include a collar movable relative to the U-shaped spring between: (a) a first locked position at least partially surrounding the arm portions of the U-shaped spring preventing separation of the arm portions to release the strike after the strike has passed through the U-shaped spring, and (b) a second unlocked position removed from the arm portions of the U-shaped spring permitting separation of the arm portions to release the strike after the strike has passed through the U-shaped spring.
It is thus a feature of at least one embodiment of the invention to provide a latch permitting simple addition of a locking function.
The U-shaped spring may be held substantially fixed with respect to the support bracket and the collar is movable with respect to the support bracket.
It is thus a feature of at least one embodiment of the invention to permit a locking during engagement of the latch and strike such as may impart a high frictional resistance to movement of the U-shaped spring.
The latch strike retention assembly may further include an electrically powered actuator moving the collar with respect to the support bracket between the locked and unlocked position in response to an electrical signal.
It is thus a feature of at least one embodiment of the invention to permit automatic locking of the door at certain appliance operating stages.
The actuator may be at least one electrical solenoid and/or may include a thermal actuator preventing movement of the collar from the locked to the unlocked position when power is disconnected from the electrical solenoid for a predetermined period of time corresponding to a thermal cooling.
It is thus a feature of at least one embodiment of the invention to permit rapid locking action as may be necessary for certain safety features while ensuring residual locking even under power loss conditions that nevertheless ultimately permit access through an unlocked door.
The latch strike retention may further include a strike sensor communicating with a first contact set to provide a signal dependent on engagement of the strike with the U-shaped spring.
It is thus a feature of at least one embodiment of the invention to permit determination of proper door position for locking.
The collar may further communicate with the first contacts to provide a signal dependent on engagement of the collar with the arm portions of the U-shaped spring.
It is thus a feature of at least one embodiment of the invention to permit a single signal to be used for effective lock control. By providing a signal only when the strike is in position and the collar properly placed, door closure can be detected by momentary operation of the electronic actuator and monitoring of the contacts, and complete locking may be confirmed by closure of the contacts.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.
a-c are front elevational, fragmentary side elevational and fragmentary top plan views of the strike engaged with the latch mechanism of
a and 7b are front elevational views of the U-shaped spring clip in an embodiment in which the spring clip is moved along the plane by an electric actuator to place the ends in between the walls of a collar to provide a locking;
a and 8b are figures similar to those of
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.
Referring now to
Referring now to
The strike retention mechanism 28 may include a U-shaped spring 32 and a support bracket 30 constructed of injection-molded thermoplastic. The U-shaped spring 32 provides two upwardly extending arms 36 formed by bending a round cross-section of steel wire in a U-shape until the arms 36 are substantially parallel as extending away from a base 39. During use, as will be described, arms 36 may flex to pivot apart about an approximate pivot axis 38 parallel to but displaced from the axis 24 and in a plane 31 generally perpendicular to the axis 24 to admit the bulbous end 26 of the strike 20.
The U-shaped spring 32 is retained in proper position to receive the strike 20 as corralled by the support bracket 30 which includes an escutcheon panel 40 abutting a rear surface of the front panel 14. The escutcheon panel 40 includes an escutcheon aperture 42 allowing the strike 20 to pass through the escutcheon panel 40 to be received between the arms 36 of the U-shaped spring 32. The escutcheon aperture 42 is surrounded by a collar 44 which has an outer periphery fitting snugly into the latch opening 22 of the front panel 14 and a beveled interior periphery helping to funnel the strike 20 into alignment with the escutcheon aperture 42. The escutcheon panel 40 may be held against the front panel 14 by means of one or more screws 46 (only one shown for clarity) received by corresponding bores 48 in the escutcheon panel 40.
Referring now to
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Movement of the U-shaped spring 32 in this manner may be accomplished by an electric actuator 74 attached to the base 39, directly or through a linkage or the like, to allow both electrically controlled unlocking and locking with opposite motions of the electric actuator 74. The electric actuator 74 may be any of a variety of electric actuators including single solenoids with permanent magnet cores, a single solenoid with a spring bias, opposed dual solenoids with standard ferromagnetic cores, wax motors, and bimetallic elements, electric motors, or the like.
Referring now to
This embodiment may also provide for a pivoting strike sensor 86 having a first end 88 positioned between the arms 36 and within the opening 22 as shown in
The result is that the contacts 84 may close only when both the collar 72″ is engaged on the distal ends 62 locking the strike 20 into the strike retention mechanism 28 and the strike 20 is engaged by the U-shaped spring 32. This approach provides reduced wiring for the communication of both lock state (indicating a locking of the strike retention mechanism 28) and door closure state (indicating engagement of the strike 20 with the U-shaped spring 32).
In one embodiment, (shown in
Alternatively, the actuator 74′ may be used alone and may be a thermal actuator if a slow locking speed may be tolerated.
The present invention contemplates that the arms 36 of the U-shaped spring 32 may be coated with a friction reducing substance such as a thermoplastic or may incorporate rollers or the like at points of contact with the strike 20 for the similar purpose, and/or that the strike 20 may be thermoplastic or have a thermoplastic coating over a metal core for similar friction reduction. The U-shaped spring 32 need not in all embodiments be formed of a single metal rod, but may be formed from two wires that are welded together or otherwise attached.
Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “left”, “right”, “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence, or order unless clearly indicated by the context.
When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.
This application claims the benefit of U.S. provisional application 61/327,945 filed Apr. 26, 2010 and hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US11/32406 | 4/14/2011 | WO | 00 | 9/20/2012 |
Number | Date | Country | |
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61327945 | Apr 2010 | US |