Sliding and tilting door assembly

A cooking appliance includes an outer cabinet within which is provided an oven cavity which can be selectively accessed by movement of a door mounted through a door linkage system which enables the door to be shifted between opened and closed positions through either sliding or tilting movements. In particular, the door can be automatically or manually shifted between open and closed positions, through either the sliding or tilting motions. In accordance with another aspect of the invention, the door can be automatically opened at the end of a process or cooking cycle, or manually opened.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the art of cooking appliances and, more specifically, to a selectively sliding and tilting door assembly particularly designed for use on a microwave oven.

2. Discussion of the Prior Art

It is widely known to provide a cooking appliance with a single, generally rectangularly shaped door that pivots about a defined axis. That is, top and bottom portions of the oven door are pivoted to a cabinet of the oven and the door is pulled outward from the appliance about a hinge axis to provide access to the oven cavity. For example, it is common to have a microwave oven door which is pivoted about a vertical axis. While this type of oven door has found wide spread use, it is not entirely satisfactory for every application. For instance, an oven door that rotates about a vertical axis projects outward from the appliance a considerable distance. This distance must be taken into consideration when deciding where to locate the appliance. Otherwise, the opened door could interfere with traffic or other patterns or even access to surrounding areas. In addition, such an oven door may require a user to move to one side of the appliance to fully open the door. In order, to address this problem, some manufacturers provide their ovens with other door configurations, such as doors which pivot about horizontal axes, with such arrangements having similar drawbacks.

The problems of access and space is of particular concern in connection with commercial kitchens such as found in fast food chains. In these locations, time and space are critical. In any case, despite the existence of various known door configurations, particularly for oven doors, there still is seen to exist a need for a. versatile door system. More specifically, there exists a need for a door system which can be used in various modes and which permits a door to move between opened and closed positions in various ways, thereby providing for at least, different access configurations.

SUMMARY OF THE INVENTION

The present invention is directed to a door linkage system for a. cabinet, particularly a cabinet of a cooking appliance and, more particularly, a cabinet of a microwave oven, wherein the door can be shifted between opened and closed positions through either sliding or tilting movements. In accordance with another aspect of the invention, the door can be automatically opened at the end of a process cycle, or manually opened.

In accordance with the most preferred embodiment of the invention, an oven cavity is established within a microwave oven cabinet, with the oven cavity having top, bottom, rear and opposing side walls that collectively define a frontal opening. In accordance with the invention, the cabinet is provided with a door which can be automatically or manually shifted between open and closed positions. More particularly, the door can be manually or automatically shifted, through either sliding or tilting motions, between opened and closed positions.

Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With initial reference toFIGS. 1 and 2, a microwave oven constructed in accordance with the present invention is generally indicated at5. As shown, microwave oven5includes an oven or process cavity10arranged within an outer cabinet15defined, at least in part, by a rear wall20exposed upon opening a door25having a handle27. Door25is vertically, slidably movable between a closed position as shown inFIG. 1wherein venting louvers30in an upper component housing portion32are exposed and an open position exposing cavity10as shown inFIG. 2. In the embodiment shown, arranged below cavity10on a front portion of microwave oven5is a control panel35including a multi-segment display40, a numeric keypad section50, an entry button55, a power level button57, a start button59and a stop button60. In the embodiment shown, cavity10is in the order of 13 inches (approx. 33 cm) wide, 8 inches (approx. 20 cm) deep and 6 inches (approx. 15 cm) in height. However, at this point, it should be noted that the particular construction, size and control panel configuration shown in these figures are only presented for exemplary purposes and can vary greatly in accordance with the overall invention. Although not shown, microwave oven5includes one or more magnetrons for generating microwaves which are directed into oven cavity10during a cooking operation. With this basic arrangement in mind, the present invention is particularly directed to the mounting and movement of door25as detailed fully below.

As indicated above, the door25of microwave oven5can open through each of a sliding action and a tilting action as will be detailed more fully below. To perform these functions, door25is mounted through the structure best shown inFIGS. 3 and 4. Again, the depicted, preferred embodiment of the invention presents oven5as a microwave oven having a cooking or process cavity10having an open frontal portion which is adapted to be closed by door5. Pivotally mounted at a frontal end (not separately labeled) is a combination spring and damper assembly (GSR)75. This pivotal mounting establishes a fixed pivot axis. In one aspect, spring and damper assembly75provides force to open door25and, in another aspect, provides operational damping during the movement of door25. Although various types of spring and damper combinations could be employed, an extensible, coil spring wrapped pneumatic damper is preferably employed. At this point, it should also be understood that the damping is not actually required for operation but does improves smoothness of operation.

A trailing arm85is pivotally connected to door25at a pivot point F. Basically, trailing arm85converts force of spring and damper assembly75into an opening force at a top joint of door25. A tilt link90connects to a leading arm100at a joint L and is provided with a cam follower110shown in the form of a pin H. A cam link120is pivotally mounted within outer cabinet15at a joint C. Cam link120acts through cam follower110with force from a cam spring125acting on a cam link profile K to provide a desired force at a leading edge door connection L at a given tilt position for door25.

More specifically, cam follower110is held against cam link120by cam spring125, and employs sliding or rolling contact against cam link120to provide the desired force on leading arm100. At the same time, cam spring125is connected to cam link120at pin J, while acting on cam link120to create a moment about pivot point C which creates a reaction force at contact pin H between cam follower110and cam link profile K.

At the same time, leading arm100is connected to tilt link90at joint L and door25at joint M. Leading arm100interacts with a latch pawl140along a leading arm latch profile N to provide latching for door25. Latch pawl140is preferably mounted to appliance5at a joint P, while defining a pin or roller that interacts with leading arm profile N to establish a latch that resists an opening force applied by spring and damper assembly75.

A latch spring145is connected to oven5at Q and to pawl140at R. Latch spring145acts on latch pawl140to provide a moment on latch pawl140about joint P to provide a force establishing an engagement between latch pawl140and leading arm100at leading arm profile N. An unlatch actuator150, such as a solenoid actuator, connects to latch pawl140. Unlatch actuator150acts on latch pawl140to provide a force applied at connection point S to overcome a force of latch spring145in order to disengage latching at pawl140and leading arm profile N.

With specific reference toFIGS. 3-5, the sliding action of the door is described as follows:

I. Normal Operation Mode Closing

In the open position (seeFIG. 4) the door25is held in the full open position by the force of the spring and damper assembly75acting on the trailing arm85at a joint A, creating a moment about D, which creates force on the door25at F which holds the door25open. Positioning of the leading edge of the door25is maintained by the reaction between the cam follower110, the cam link profile K, and the moment on the cam link120created by the force applied by cam spring125. The cam link profile K is configured such that, when the door25is near the closed or operating position, the reaction between the cam follower110and cam link profile K creates a moment about D acting on the tilt link90such that the tilt link90acts through the leading arm100to pull the leading edge of the door25towards the operating position next to the appliance.

To close the door25, the operator applies a closing force on the door25through handle27which is sufficient to overcome the force of the combination spring and damper assembly (GSR)75. This moves the door25towards the latch pawl140. As the door25approaches the closed position (seeFIG. 5), the leading arm latch profile N comes into contact with the latch pawl140. The leading arm profile N is configured such that it acts on the latch pawl140to overcome the moment, about P, created by latch spring145, displacing the latch pawl140and allowing the latch pawl140to travel around the leading arm latch profile N.

When the door25has reached the fully closed position, the leading arm latch profile N is configured to allow the latch pawl140to move behind the leading arm latch profile N. The moment on the latch pawl140about P, rotates the latch pawl140into the latched position. In this position, the engagement between the latch pawl140and leading arm profile N is configured such that the opening force on door25created by the combination spring and damper assembly75acting through the latch pawl140is at or near perpendicular to the leading arm latch profile N. At this point, the operator removes the force applied to the door25and the door25is retained in the latched position, i.e., the door25is in the closed and latched position (seeFIG. 3). The appliance control initiates the opening cycle by actuating the unlatch actuator150. The unlatch actuator150acts against the pawl140to overcome the moment about D created by the latch spring145and creates a moment about D in the opposite direction. This moment acts on the latch pawl140and rotates it such that the latch pawl140is no longer engaged with the leading arm latch profile N. When the latch pawl140is disengaged from the leading arm100, there are no forces present to resist the force of the spring and damper assembly75which acts on the trailing arm85at A, thereby creating a moment about D which creates an opening force on the door25at F, leading to the door25slidably moving to the fully open position shown inFIG. 4.

II. Automatic Door Opening

Automatic unlatching enables the door to open automatically at the end of the process cycle. This saves the operator the time and motion required to open the door, leaving the operator available to perform other tasks. In addition the automatic opening provides visual cue that the appliance process is complete.

Starting with the door25is in the closed and latched position (seeFIG. 3), the operator applies a door opening force to the door25through handle27. Some component of this force is directed outward from the appliance. To this end, at least the lower door location and grip configuration of handle27assures that this outward force component is created by a typical interaction between the operator and the door handle27. In any case, the outward component of this force applied to the door25acts through the leading arm100to overcome the moment about D on the tilt link90and slightly rotates the tilt link90which moves leading arm100and leading arm latch profile N away from the latched position. The latch pawl140is prevented from moving with the leading arm100by contact with bumper structure T. This motion of the leading arm100with respect to the latch pawl140acts to disengage the latch pawl140from the leading arm latch profile N. When the displacement is sufficient for the unlatching to be complete, the spring and damper assembly75acts through the overall mechanism to move the door25to the open position. The reaction between the cam link120and the tilt link90will return the leading edge of the door25at M to the operating position.

At this point, it should be noted that optional manual unlatch methods can be employed as well. For instance, the operator can apply a force to a mechanism (not shown) which acts either directly or indirectly on the latch pawl140to perform unlatching as described in the automatic door opening sequence above. In an alternative arrangement, the operator can apply a force to a mechanism that acts either directly or indirectly to displace the leading arm100with respect to the latch pawl140as described in the manual opening sequence above. This could be accomplished by displacing the leading edge of the door or slightly rotating the tilt link.

With specific reference toFIGS. 6-9, the tilting action of the door25is described as follows:

IV. Door Tilt Operation

The main purpose of the tilt operation is to enable the door25to quickly be rotated about the trailing arm joint at F and maintained in a rotated position for improved access to the oven cavity10. To tilt the door25, the operator applies a pulling force to the leading edge of the door25and continues to apply a force approximately tangent to the door movement as the door25pivots about joint F. The door25is intended to be in the open position for tilting, but the tilt can be initiated to any position. However, the spring and damper assembly75and cam reaction forces tend to pull the trailing arm85to the open position when the door25is substantially rotated away from the operating or closed position.

As the door25is rotated to the tilted position, the configuration of the cam link6with cam link profile K acts on the cam follower110due to a moment about point C created by force from cam spring125(hereafter referred to as “cam reaction”). As depicted, the mechanism is configured to provide variable forces through the swing. More specifically, at small angles of door displacement from the operating position, the reaction pulls the leading edge of the door25towards the operating position and holds it in that position (FIG. 6). As door displacement from the operating position is increased, the door25reaches a neutral point where the cam reaction is neutral such that the cam reaction is not forcing the door25in either direction. When moving the door25to the operating position from the tilt position, the operator will feel the mechanism pull the door25towards the operation position when it is moved past the neutral point (FIG. 7).

As displacement is increased, the cam reaction changes direction and resulting forces are slightly biased towards moving the door25to the full tilt position. This provides a light feel for the operator and gives some control to the motion. When moving the door25from the tilt position to the operation position, this portion of the cam inhibits the door25from slamming back to the operation position. (FIG. 8). As the door25approaches the fully tilted position, the cam reaction creates sufficient force that the door25is held in the tilted position without any operator force applied. Therefore, the operator must apply a force to the door25to start the motion back towards the operating position (FIG. 9).

Based on the above, it should be readily apparent that the invention provides a versatile door assembly which can be manually or automatically shifted between closed and opened positions, with the door being shiftable through either a sliding or a tilting movement. More specifically, the open and closing mechanism employs a linkage system which can provide a slide action which allows the door to move between closed and open positions in an approximately linear motion, thus minimizing intrusion of the door action into an adjacent workspace. With this arrangement, an operator does not have to swing the door open or change position to accommodate door swinging, thereby improving efficiency and flexibility. In addition, access to the oven cavity or other internal cabinet region is the same from either side of the cabinet. Particularly advantageous in connection with fast food chains, the door assembly enables process items to be placed in front of the appliance because the door does not need to swing through a space in front of the appliance. In addition, the door can open automatically upon completion of a process operation, thereby providing a visual cue that the operation is finished. The net effect is significantly reduced operator time and effort. In connection with tilting the door for interior access, the linkage mechanism can be tailored to provide a desired operator feel or door motion. As disclosed, the mechanism advantageously provides a pull back force at small angles of displacement which resists movement of the door from an operating position. As the tilt angle is increased, the reaction of the mechanism provides a neutral or slight force aiding the movement towards the tilt position. Finally, at the full tilt position, the mechanism increases the force to hold the door in that position and provide a detent feel for the operator. Although described with reference to preferred embodiments of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. In general, the invention is only intended to be limited by the scope of the following claims.