Abstract:
A linkage mechanism provides for the extension and retraction of rooms in recreational vehicles while maximizing the space inside the vehicle. Braced parallel linkage members are applied between a vehicle frame member and an expandable room member. A hydraulic cylinder or other force assist element may be used to drive a slotted glide arm which, in turn, causes the braced parallelogram linkage to shift, thus pulling or pushing the room frame member relative to the vehicle.

Description:
BACKGROUNG OF INVENTION 
     The invention relates to a braced parallelogram linkage for moving members together or apart in a substantially linear motion without a substantial shift in a direction perpendicular to the desired linear motion. Typical parallelogram linkages that are commonly used for a variety of purposes involve a pair of parallel members attached pivotally to a pair of parallel linkage members. If one of the parallel members is fixed, then motion of the parallelogram linkage results in an angular motion—in or out and up or down rather than simply in or out. The present invention relates to a generally straight motion parallelogram linkage. 
     The invention disclosed herein is particularly useful as a control mechanism for expandable rooms in habitable structures, especially room structures that are telescopically slideable between retracted and extended positions for motorized or towed vehicles. A variety of vehicles are known and used that have a room or a room portion that may be moved from a retracted position while the vehicle is moving over the road to an extended position when the vehicle is stationary in order to provide additional internal space. This type of an arrangement provides adequate space to accommodate users when a recreational vehicle is parked for habitation while still keeping the vehicle within governmental regulations that impose width limitations for vehicles on roads and highways. When these vehicles are stationary, they are frequently used for habitation for extended periods of time, and when so used, it is highly desirable to be able to maximize the available living space. This is done in a variety of ways in which the user can move a “nested” portion of the expandable room out to its extended or expanded position, typically under hydraulic or electrical power. 
     These expandable room portions usually comprise a structure that includes a floor, a roof, an external side wall (typically generally parallel to the vehicle side wall), an open (or openable), interior side wall, and one or more end walls (typically generally perpendicular to the vehicle side wall). These components are typically made of frame members and wall panels. In the retracted position, the roof, floor and end walls are typically concealed from exterior view and the room exterior side wall forms a portion of the vehicle side wall. A large factor in the purchase of a vehicle of this type is the amount of space that is available inside the vehicle. Thus, it is desirable that the mechanism for extending and retracting the room occupy a minimum amount of space within the vehicle. 
     The prior art for expanding and retracting expandable rooms generally employs hydraulic arms that are housed inside the vehicle or under the floor of the vehicle. The hydraulic arms housed inside the vehicle require a housing unit when they are in their retracted position. This housing unit remains intact when the room is extended taking up space within the vehicle. 
     The hydraulic arms that are housed under the floor are generally complex, relatively expensive, and may be unduly heavy. The additional weight also adversely affects the fuel economy of the vehicle. With the highly competitive market in these recreational vehicles, cost and reliability of operation are important factors. Further, when the room is in the retracted position, otherwise available storage space under the floor is lost. 
     It is therefore an object of the invention to provide an improved mechanism for expandable rooms for vehicles that is relatively inexpensive to manufacture, reliable in use, lightweight, and which will allow for maximum space inside the vehicle. It is a further object to provide a braced parallelogram linkage that permits motion of members together or away from one another in a substantially linear path without substantial movement of said members in a direction perpendicular to said path. It is a further object to provide a mechanism for the expansion and retraction of expandable rooms or structures when the rooms or structures are not disposed for convenient housing of the mechanism in the floor. Finally, it is an object of the present invention to provide such a parallelogram linkage mechanism wherein a force assist means such as, for example, a hydraulic cylinder, electric drive, or pneumatic control system may drive the movement of the braced parallelogram linkage. 
     SUMMARY OF INVENTION 
     The present invention includes an extension assembly for manual operation or having a hydraulic cylinder or other force assist such as a pneumatic control system, electric drive or other similar system, mounted to effect the coordinated movement of braced parallelogram linkage members through the actuation of a glide arm or rolling support arm. The glide arm or rolling support arm preferably moves generally along a first structural member such as a vehicle frame member as the hydraulic cylinder rod extends or retracts relative to the cylinder body or as manual operation moves structural members relative to one another. The glide arm is pivotally connected to the exterior ends of braced parallelogram linkage members that extend to points of pivotal attachment with a second structural member, such as expandable room members. The glide arm has an opening formed therein to accommodate movement of the glide arm about a bracing member that is pivotally attached to the first structural member such as vehicle frame member. 
     The braced parallelogram linkage members comprise a first parallel linkage member that is braced by a first parallel linkage bracing member, and a second parallel linkage member that is braced by a second parallel linkage bracing member. The parallel linkage bracing members are pivotally attached to the respective parallel linkage members and they are also attached to the first structural member. In this manner, movement of the glide arm or rolling support arm causes the exterior ends of the parallel linkage members to move and pivot thus extending or retracting the room and changing the relative angles between the parallel linkage members and the parallel linkage bracing members, the parallel linkage members and the first structural member, and the parallel linkage members and the second structural member, respectively. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a side elevation view of the extension assembly in the retracted position that accompanies an expanded room. 
     FIG. 2 is a side elevation view of the extension assembly in the extended position that accompanies a retracted room. 
     FIG. 3 is a side view of the hydraulic cylinder rod attachment to the gliding support arm. 
     FIG. 4 is a side view of the hydraulic cylinder attachment to a vehicle frame member. 
     FIG. 5 is a top, cross-sectional view of the pivotal connection of the vehicle frame member and the second parallel linkage-bracing member. 
     FIG. 6 is a top cross-sectional view of the pivotal connection of the second parallel linkage member to the gliding support arm within the vehicle frame member. 
     FIG. 7 is a top cross-sectional view of the vehicle frame member showing the pivotal mounting of the first parallel linkage bracing member to the frame member through the slot of the gliding support arm. 
     FIG. 8 is a vehicle interior side view of the first parallel linkage member pivotal attachment to a room mount. 
     FIG. 9 is an end view of the first parallel linkage member pivotal attachment to an expandable room mount. 
     FIG. 10 is an interior end view of a coach having an expandable room wherein the room is retracted and the parallelogram linkage is extended. 
     FIG. 11 is an interior end view of a coach having an expandable room wherein the room is extended and the parallelogram linkage is retracted. 
    
    
     DETAILED DESCRIPTION 
     Referring first to FIGS. 10 and 11, there is illustrated a motor vehicle such as a recreational vehicle  56  that has extending from an opening in its side wall an expandable room or room structure indicated generally by the reference numeral  54 . In FIGS. 10 and 11 the expandable room shown is raised and serves as wardrobe or cupboard space. Of course, rooms of various sizes may be used. FIG. 11 shows the expandable room in its extended position to provide additional living or storage space inside the recreational vehicle when the vehicle is stationary, such as at a campsite. As is well known to those skilled in the art, when the vehicle is traveling over the road, the expandable room  54  is retracted as shown in FIG. 10 so that the side wall  58  of the expandable room  54  is generally flush with an exterior wall  60  of the recreational vehicle  56 . 
     FIGS. 1 and 2 show the extension assembly ( 62  overall) for extending and retracting the raised room. FIG. 1 shows the extension assembly in the retracted position (extended room position) while FIG. 2 shows the extension assembly in the extended position (retracted room position). A glide support arm  14  is housed generally within or along a first frame member  26  such as a frame member of a vehicle. A braced parallelogram linkage comprising first and second parallel linkage members  18 ,  22  and first and second parallel linkage bracing members  20 ,  24  is shown. The first and second parallel linkage members  18 ,  22  are pivotally mounted to a second frame member such as an expandable room frame member expandable room on expandable room members located within the recreational vehicle  56 . As the braced parallelogram linkage moves from its extended position to its retracted position, towards the vehicle side wall  60  the expandable room portion is pulled from within the recreational vehicle  56  to extend outwardly from the recreational vehicle  56  when the braced parallelogram linkage is in its retracted position. Of course, the attachment could be reversed to mount the hydraulic cylinder along the expandable room exterior side wall in which case the mechanism would push the room outwardly and pull the room inwardly. Mounting the mechanism to a vehicle frame member is preferred for preserving space. 
     A hydraulic cylinder  10  having a hydraulic cylinder rod  12  extendable therefrom is attached to the vehicle frame  26  as shown in FIG.  4 . The hydraulic cylinder rod  12  has an outer end attached to a first end  64  of the glide arm  14 . The glide arm  14  has a longitudinal opening or slot  16  formed therein between the glide arm first end  64  and second end  66 . The first parallel linkage member  18  is pivotally combined with and extends between the glide arm  14  and a second frame member mount or room mount  52 . The second parallel linkage member  22  is pivotally combined with and extends between the glide arm second end  66  and a room mount  52 . In this manner, the glide arm  14  and the ends of the attached parallel linkage members  18 ,  22  may move generally along the first frame member  26  as the hydraulic cylinder rod  12  is extended or retracted. 
     First and second parallel linkage bracing members  20 ,  24  are pivotally combined with the first frame member  26  and with the first and second parallel linkage members  18 ,  22 , respectively. In this manner, the motion of the pivotally mounted parallel linkage members  18 ,  22  is constrained by the bracing members  20 ,  24 . In the preferred arrangement, the second parallel linkage bracing member  24  is pivotally mounted to the frame member  26  at a location beyond the range of motion of the glide arm  14 . The first parallel linkage bracing member  20  is pivotally mounted to the frame member  6  at a location within the path of the slot or opening  16  formed in the glide arm  14 . In this manner, the attachments of the parallel linkage bracing members  20 ,  24  to the first frame member  26  do not interfere with the movement of the glide arm  14 . 
     There are preferably provided stop pins  28 ,  30  mounted to extend outwardly from the room mount  52  to provide a defined stopping point and to prevent over-extension of the room. 
     As disclosed in FIG. 3, the hydraulic cylinder rod  12  is attached to the glide support arm  14  to force the glide support arm  14  to move generally along the frame member  26 . FIG. 5 illustrates the pivotal connection of the second parallel linkage bracing member  24  and the first frame member  26  via a second parallel linkage bracing member pin connector  32  having bearings  50  mounted thereon to minimize lateral movement of the second parallel linkage bracing member  24  upon its pin connector  32 . FIG. 6 illustrates the pivotal connection of the second parallel linkage member  22  to the glide arm  14  via a second parallel linkage member pin connector  36 . 
     The glide arm  14  is shown to be nested and slidable within the first frame member  26 . Of course, depending on glide arm  14  or first frame member  26  configuration, the glide arm  14  may be disposed in any convenient arrangement to move generally along the frame member  26 . FIG. 7 illustrates the pivotal connection of the first parallel linkage bracing member  20  and the first frame member  26  via a pin connector  38  that is anchored to the first frame member  26  and disposed within the slot or opening  16  formed in the glide arm  14  to allow the glide arm  14  to slide within the frame member  26  about the first parallel linkage bracing member pin connector  38 . 
     FIGS. 8 and 9 illustrate the pivotal connection of the room mount  52  and the first parallel linkage member  18 . The first parallel linkage member  18  is pivotal about a first room mount pin connector  44 . The room mount  52  includes a stop pin  30  to control extension of the room or structure  54 . 
     Although the preferred embodiment as described herein includes reference to a force assist element, the present invention is intended for use with a manual force assist element or with no force assist element. Without a force assist element, the room may be manually pushed or pulled and it is preferred to employ room locks to secure the room in the extended or retracted position. 
     Having described the invention in reference to the preferred embodiment thereof, it will be understood by those skilled in the relevant art that various modifications and revisions may be made and that such modifications and revisions are intended to be within the scope of the invention as claimed below.