Patent Document

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to prior filed and co-pending U.S. Provisional Application No. 61/324,169 filed Apr. 14, 2010, entitled CASTER-SUPPORTED LIFT DEVICE, the entire disclosure of which (including the Appendix) is incorporated herein by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate generally to apparatus, systems, methods, techniques, and the like for platform lift trailers and relate generally to coupling systems therefor, including coupling a ground-supported (e.g., wheeled, wheel-supported, caster-supported or the like) lift device to a motor vehicle. Several embodiments specifically address use of a wheel-supported lift device for loading, storing, transporting and/or unloading a mobility device (e.g., a scooter, power chair, etc.), including embodiments in which the wheeled support is configured for use at road and/or highway speeds in transporting cargo such as a mobility device. Other embodiments include a trailer coupler that permits angular deflection between the trailer and a motor vehicle to which the trailer is coupled, wherein the coupler isolates and/or limits forces that would otherwise be applied between the trailer and the motor vehicle within a range of angular deflections. 
     BACKGROUND 
     Many motor vehicles are too small or otherwise ill-equipped or unable to support an externally-mounted, cantilevered lift coupled directly to and supported by a trailer hitch or the like. Such limited weight and/or other performance characteristics of these motor vehicles means that individuals who require mobility assistance in the form of mobility devices such as scooters, power chairs and the like are unable to transport such mobility devices unless they have access to a larger and/or better-equipped vehicle. Apparatus, systems, methods, techniques, etc. providing improved mobility device transfer for smaller motor vehicle would represent a significant advancement in the art. 
     SUMMARY 
     The present invention will be readily understood by referring to the following detailed description in conjunction with the accompanying drawings. A platform lift trailer includes a chassis constituting mounting and support structure to which a lift device (e.g., a mobility lift used to load, store, transport and unload mobility devices like scooters, power chairs and the like) is mounted. The chassis is configured to be coupled to a standard motor vehicle trailer hitch or the like using a platform lift trailer coupler. Some embodiments of the coupler provide protection against larges forces that might be applied between a motor vehicle and coupled trailer when they are angularly displaced relative to one another. To aid in supporting the weight of the lift (whether unloaded or loaded), one or more ground-engaging wheel assemblies are mounted to the chassis to assist in supporting the weight of the lift and any cargo (e.g., a mobility device) thereon, while not introducing an undesirable large additional weight to the back of the motor vehicle. Embodiments of the present invention thus permit adaptation of mobility lifts to a larger array of motor vehicles than otherwise possible. Also, embodiments of the present invention are highly adaptable so that a wide variety of lifts can be mounted to smaller motor vehicles. Other embodiments include a trailer coupler that uses a torque-limiting apparatus so that vertical angular displacements of the motor vehicle and a trailer coupled thereto do not apply large forces directly between the motor vehicle and the trailer. Instead, the torque-limiting coupler structure limits such forces using a biasing means such as a spring or the like to accommodate torsional forces applied between the motor vehicle and the trailer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  is a perspective view of a platform lift trailer according to one or more embodiments of the present invention. 
         FIG. 2  is a perspective view of a platform lift trailer with a platform in its folded position. 
         FIG. 3  is an exploded view of a platform lift trailer. 
         FIG. 4  is a perspective view of a platform lift trailer. 
         FIG. 5  is a front elevation view of a platform lift trailer. 
         FIG. 6  is a rear elevation view of a platform lift trailer. 
         FIG. 7  is an exploded rear elevation view of a platform lift trailer. 
         FIG. 8  is a side elevation view of a platform lift trailer. 
         FIG. 9  is a side cross-sectional view of a platform lift trailer along the line  9 - 9  of  FIG. 6 . 
         FIG. 10  is a side exploded rear elevation view of a platform lift trailer. 
         FIG. 11  is a cross-sectional view of a trailer coupling apparatus according to one or more embodiments of the present invention, detail from  FIG. 9 . 
         FIG. 12  is a detailed side view of a platform lift trailer caster assembly according to one or more embodiments of the present invention. 
         FIG. 13  is a cross-sectional side view of a platform lift trailer caster assembly according to one or more embodiments of the present invention along the line  13 - 13  of  FIG. 5 . 
         FIG. 14  is a side elevation view of a trailer coupling apparatus in an angularly displaced position according to one or more embodiments of the present invention. 
         FIG. 15  is a side elevation view of a trailer coupling apparatus in a first static position according to one or more embodiments of the present invention. 
         FIGS. 16A ,  16 B are perspective views of a platform lift trailer, wherein the lift platform is in a lowered position. 
         FIG. 17  is a perspective view of a platform lift trailer, wherein the lift platform is in a raised and open position. 
         FIG. 18  is an exploded view of a platform lift trailer, wherein the lift platform is in a lowered position. 
         FIG. 19  is a side elevation, partially exploded view of a platform lift trailer, wherein the lift platform is in a lowered position. 
         FIG. 20  is a perspective view of a platform lift trailer coupled to a motor vehicle, wherein the platform is in a raised and open platform position. 
         FIG. 21  is a side view of a platform lift trailer coupled to a motor vehicle, with the platform in its raised and open position. 
         FIG. 22  is a side view of a platform lift trailer coupled to a motor vehicle, wherein the platform is folded. 
         FIGS. 23 ,  34  are side views of a platform lift trailer coupled to a motor vehicle, wherein the platform is in a raised, open position, showing caster swiveling. 
         FIG. 24  is a top view of a platform lift trailer, with the platform in a raised and open position. 
         FIG. 25  is a perspective view of a platform lift trailer mounted to a motor vehicle, with the platform in a lowered position. 
         FIG. 26  is a perspective exploded view of a platform lift trailer mounted to a motor vehicle, with the platform is in a lowered position. 
         FIG. 27  is a side view of a platform lift trailer mounted to a motor vehicle, with the platform in a raised and open position. 
         FIG. 28  is a side view of a platform lift trailer mounted to a motor vehicle, with the platform in a raised and open position. 
         FIG. 29  is a cross-sectional view of a platform lift trailer with the platform in a raised and open position, taken along the line  29 - 29  of  FIG. 28 . 
         FIG. 30  is a side exploded view of a platform lift trailer mounted to a motor vehicle with the platform in a raised and open position. 
         FIG. 31  is a top view of a platform lift trailer mounted to a motor vehicle with the platform in a lowered position. 
         FIG. 32  is an exploded view of a two-caster platform lift trailer. 
         FIG. 33  is a rear view of a two-caster platform lift trailer. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of the invention, including the Figures, will refer to one or more invention embodiments, but is not limited to such embodiments. Rather, the detailed description is intended only to be illustrative. Those skilled in the art will readily appreciate that the detailed description given with respect to the Figures is provided for explanatory purposes as the invention extends beyond such specific embodiments. Embodiments of the invention provide towable platform lift trailer apparatus, systems, methods, techniques and the like (and/or coupling systems and the like therefor) including (but not limited to) caster-supported lift devices that make loading, storing, transporting and unloading mobility devices and the like practical in connection with motor vehicles, including smaller motor vehicles. For example, in connection with a motor vehicle that cannot support the weight, strain, etc. of a directly-vehicle-supported, externally-mounted mobility device lift (e.g., a lift directly mounted to a trailer hitch or the like on and supported solely by the motor vehicle), a ground-engaging lift trailer according to one or more embodiments of the present invention can make an external lift practical. Moreover, other embodiments of the invention include a trailer coupler that employs a biasing means to isolate torsional forces that are applied between a motor vehicle and a trailer coupled thereto when the angular relationship of the trailer and motor vehicle change (e.g., when backing out of an inclined driveway, encountering a road bump, etc.). The biasing means applies a reduced torque-limiting force and prevents the torsional forces from damaging the trailer and/or motor vehicle. Other settings and uses will be apparent to those skilled in the art after considering the following disclosure and the Figures provided herewith. 
     Reference in the specification to “some embodiments,” “one embodiment,” “an embodiment,” “various embodiments,” of the present invention and similar phrases and terms means that a particular feature, structure or characteristic described in connection with such embodiment(s) is included in at least one embodiment of the present invention. Thus, appearances of such phrases in various places throughout the specification are not necessarily all referring to the same or any specific limiting embodiment. 
     Some examples of the present invention will be shown and explained in connection with a platform lift trailer using a four bar linkage and other external mobility device lifts, such as those made and sold by Bruno Independent Living Aids, Inc. of Oconomowoc, Wis. Each such embodiment can be (and in some embodiments is) mounted to a motor vehicle having a conventional receiver hitch socket or other motor vehicle trailer-mounting apparatus. A variety of other mobility device lifts can be used from any of a number of manufacturers. No conventional “trailer bed” (i.e., a conventional supporting planar member) is required in many embodiments, thus reducing the size of the platform lift trailer when compared to many conventional trailer configurations. 
     In the platform lift trailer  100  of  FIGS. 1-10 , mounting and support structure is provided by a chassis weldment  200  that includes a support beam  210  that extends in a transverse, generally lateral orientation. A lift assembly  500  is mounted atop chassis  200  and one or more caster assemblies  400  are mounted to the underside of chassis  200  to provide support from the ground or any other support surface that each caster assembly  400  engages. A coupler assembly  300  couples platform lift trailer  100  to a motor vehicle via a conventional trailer hitch, socket or the like, so that the platform lift  500  becomes a towable platform lift. 
     One embodiment of a coupler  300 , shown in detail in  FIG. 11 , is a torque-limiting coupling means  300  and includes a motor vehicle hitch bar connector  310  that can be made of steel bar stock or the like. Holes are provided in connector  310  to permit longitudinal adjustment of the connector relative to a motor vehicle socket or other connecting apparatus. A pivot block  320  is welded to connector  310  and also can be made of steel bar stock. Block  320  and connector  310  together function as a lever  350  that is pivotably coupled to coupler channel  330  using a pivot bolt  325 . Channel  330  is rigidly mounted to chassis  200  using appropriate means (e.g., bolting, welding, and/or the like). Biasing means are used to urge lever  350  into a first static position of coaxial alignment with channel  330 . In some embodiments, the biasing means is a compression spring  340  adjacent to and bolted through channel  330  and lever  320  using spring bolt  345  to bias lever  320  into generally coaxial alignment with channel  330 . Other biasing means can be used such as a tension spring, a torsion spring, a torsion member, a gas spring, a stack of Belleville springs, elastomeric apparatus, elastic bands/straps, and the like, as will be appreciated by those skilled in the art. Also, the biased lever structure of the coupler  300  can be adjusted in various ways. For example the pivot axis and biasing means can be located at the juncture of the channel  330  and chassis  200  (e.g., lift bracket  220 ). Other equivalent structures to the torque-limiting coupling means  300  will be apparent to those skilled in the art. 
     The following discussions of torsional forces between embodiments of a motor vehicle and a platform lift trailer or other trailer coupled thereto will refer to “vertical angular displacement” between the motor vehicle and trailer. For consistency in describing such displacement, the trailer can be assumed to maintain a generally horizontal position while the motor vehicle&#39;s angular position changes relative to the generally horizontal trailer orientation. Therefore, when a motor vehicle and coupled trailer traveling forward encounter a ramp, inclined driveway or other inclined path, it is assumed that the it is the motor vehicle that changes position, thus generating a counterclockwise torsional force on connector  310 , as shown by arrow  390  in  FIG. 11 . As will be appreciated by those skilled in the art, this assignment of terminology can also be used to describe equivalently a situation in which the trailer moves “upward” relative to the motor vehicle, for example when the motor vehicle and trailer are backing up and reach the bottom of a ramp or inclined driveway. 
     When such a counterclockwise torsional force is applied to connector  310 , as indicated by arrow  390  in  FIG. 11 , biased lever  350  resists rotation out of channel  330  due to the force exerted by biasing means  340 . When the biasing force of spring  340  is overcome, the pivoting of lever  350  defines a coupler displacement angle α upward from horizontal (this angle α can be limited by the length of spring bolt  345  to set a maximum angular displacement between the chassis and any coupler lever, and in other ways well known to those skilled in the art). Therefore, as the upward vertical angular displacement angle ct between a motor vehicle and platform lift trailer  100  increases, angle Gt increases and the resistance of spring  340  works to prevent the weight of the motor vehicle from being applied directly and fully to the device  100 . Instead, only the resistance force of the biasing means  340  is applied. Using the configuration of the torque-limiting coupling means  300  shown in  FIGS. 1-10 , no “downward” vertical angular displacement is accommodated, though such accommodation is readily achievable using alternate embodiments of the coupler. 
     Another embodiment of the motor vehicle coupling means is shown in  FIGS. 14 and 15 , wherein a bracket  370  is secured to lift mounting bracket  220 . Lever bracket  330  is pivotably coupled to bracket  370  using a bolt  375  of other pivot. A biasing spring  340  is coupled to both the lift mounting bracket  220  and the lever bracket  330  to urge the lever bracket into the resting or static position shown in  FIG. 15 . When a counterclockwise torsional force is applied to lever bracket  330 , for example by a motor vehicle to which lever bracket  330  is hitched, spring  340  limits the force applied to the trailer and/or the motor vehicle, but allows pivoting of the lever bracket  330  into an angularly displaced position, as seen in  FIG. 14 . 
     As noted above, the lift-supporting and ground-engaging wheel apparatus can include one or more casters, etc. Each of the two caster assemblies  400  shown in  FIGS. 1-10  includes a caster tire  440 , which also can be another type of wheel or comparable apparatus, including a highway-suitable tire. As can be seen from the Figures, each tire  440  is able to swivel fully using a swivel mounting apparatus  410 . Splash guards  470  protect cargo loaded on the lift device  100  from water, road debris, road salt, etc. Each caster assembly  400  also has a caster suspension apparatus  460 . In platform lift trailer  100  shown in  FIGS. 1-10 , caster suspension apparatus  460  is the same or similar to the well-known apparatus shown in U.S. Pat. No. 3,208,168 issued to Henschen on 28 Sep. 1965 and/or U.S. Pat. No. 3,436,069 issued to Henschen on 1 Apr. 1969. Henschen describes “an elastic torsion joint” having “concentrically arranged inner and outer tubular members of a polygonal cross-section.” The inner member is spaced from the outer member by a plurality of elongated cushioning rollers disposed between an external surface of the inner member and a pair of intersecting internal surfaces of the outer tubular member. This configuration yieldingly resists relative rotation of the inner and outer members about a generally common axis. A load supporting arm is connected to one end of the inner member and can be a caster mounting bracket  445 . 
     As seen in  FIGS. 12 and 13 , suspension apparatus  460  includes tubular housing  462  containing a number of cushioning elements  464  that can be made of elastomeric material or the like and act as cushions, cushioning rods or the like. Torsion shaft  466  fits within housing  462  and elements  464  so that elements  464  resist torsional forces applied by shaft  466  as it rotates when tire mounting bracket  445  rotates shaft  466  (e.g., when tire  440  hits a road bump). Suspension apparatus  460  for each caster tire  440  can be bolted to the swivel apparatus  410  that extends through beam  210 . In some embodiments, suspension apparatus  460  cooperates with the torque-limiting coupling means  300  discussed above to further reduce the risk of damage to trailer  100  or a motor vehicle when there is upward vertical angular displacement between trailer  100  and a motor vehicle to which the trailer  100  is coupled (e.g., when backing out of a driveway, parking lot, inclined parking space, or the like). In other embodiments a trailer can include (instead of or in addition to the suspension described above) wheel or caster suspension means such as a conventional motor vehicle shock absorber, a coil over shock absorber apparatus, a gas spring, and/or an elastomeric member. As will be appreciated by those skilled in the art, the caster suspension and force-limiting coupler are configured to and work in combination to reduce the risk of damage to or undesirable behavior by the trailer and/or a motor vehicle. 
     Chassis  200  also includes a lift mounting bracket  220  in embodiments of trailer  100  shown in  FIGS. 1-10 . A lift  500  is mounted to bracket  220  using bolts and/or other appropriate lift mounting means. In  FIGS. 1-10 , lift  500  uses a four bar linkage system and can be used to load, store, transport and unload personal mobility devices. With such four bar linkage lifts, a lift platform  520  moves in a generally continuous motion from its stored position to its fully deployed position (i.e., open and resting on the ground or other surface). The platform is fully raised and retracted when in its stored position, which includes platform  520  being in its “open” configuration (shown, e.g., in  FIG. 1 ) and in its “folded” position (shown, e.g., in  FIG. 2 ). 
     Other lift configurations are usable with embodiments of the platform lift trailer and include two-stage platform movement mechanisms that separately control horizontal movement and vertical movement to extend and retract the lift platform horizontally with a horizontal movement mechanism, and to raise and lower a platform vertically using a vertical movement mechanism. Variations and combinations of these operations also are found in various lifts (e.g., lifts using a four bar linkage combined with a horizontal slide mechanism to move the entire four bar linkage and platform horizontally during use). Control of a given lift&#39;s operation is governed by a control mechanism  580  or the like, which controls actuators and the like to move platform  580  as desired. Electrical and/or other power for operation of the platform lift trailer can come from a motor vehicle&#39;s battery or an auxiliary power source, as will be appreciated by those skilled in the art, and such power source(s) will be understood to be part of control mechanism  580  in the embodiments shown, described and claimed herein. 
     These lifts are particularly helpful in loading, storing, transporting and unloading personal mobility devices such as scooters, power chairs and other products used by physically challenged individuals. The four bar linkage lift  500  of  FIGS. 1-10  uses link arms  510  controlled by one or more actuators  512  or the like. As will be appreciated by those skilled in the art, the coupling of trailer  100  to a motor vehicle means that lift  500  is supported by both each caster assembly  400  (i.e., by the ground or other support surface) and the motor vehicle itself. This configuration distributes the weight of the lift and any other equipment and/or components and provides a stable base for operating lift  500 . Swiveling of tires  440  allows reasonable motion of trailer  100  when coupled to a motor vehicle moving in a forward or backward direction. When moving in reverse, the substantially rigid lateral connection between trailer  100  and a motor vehicle reduces jackknifing and/or other undesirable behavior, actions and problems. The torque-limiting coupling means used in some embodiments of a platform lift trailer and shown in the Figures also provides limited protection against damage when the trailer and a motor vehicle to which it is coupled encounter vertical angular displacements that increase angle α. 
     As will be appreciated by those skilled in the art, embodiments of the platform lift trailer are constructed using materials, components and in a manner that permits use of the platform lift trailer on roadways, highways, etc. at and in normal transportation speeds and conditions. Other apparatus can be used (e.g., tarps, covers, etc.) to further protect cargo on a platform lift trailer during storage and/or transportation. 
     As seen in one or more other embodiments shown in  FIGS. 16A-24 , a platform lift trailer  1100  includes a mounting plate  1200  that is configured to be mounted to a motor vehicle using a hitch tongue assembly  1300  that has a hitch tongue  1330  configured to engage a conventional receiver hitch socket (e.g., socket  75  on a motor vehicle  70 , as shown in  FIG. 22 ). Hitch tongue assembly  1300  can be bolted and/or welded to mounting plate  1200  or affixed thereto in any other appropriate manner. Hitch tongue assembly  1300  may be adjustable, for example having height adjustment facilitated by telescoping mounting tubes  1340 . 
     A caster assembly  1400  is mounted to the underside of mounting plate  1200 , for example by bolting plate  1200  to a swivel mount  1410 , thus coupling a wheel support  1420  to plate  1200 . Wheel support  1420  can be a single member bracket as shown in some embodiments of the Figures or can be use multiple members to couple one or more caster wheels  1440  to mounting plate  1200  ( FIGS. 32 and 33  illustrate one or more additional two-wheel embodiments of a platform lift trailer). The swivel allows wheel(s)  1440  to turn as needed during use. Wheel(s)  1440  are mounted to wheel support  1420  using an axle  1450 , which may be of conventional configuration or may be specially configured to accommodate structures provided to stabilize and/or improve operation of device  1100  during higher speed operation on a highway or the like. 
     As above, some embodiments of the lift assembly  1500  shown in  FIGS. 16A-24  can include a four bar linkage lift. The four bar (parallelogram) linkage  1510  is driven by an actuator and/or cylinder configuration  1512  extending from a hood  1570  or the like and allows the lift device platform  1520  be extended laterally (horizontally) and downward for loading, as shown in  FIGS. 16A-24 . This “out and down” motion defines an arc or other travel path for the lift platform  1520  around the caster wheel(s)  1440 . By using this configuration, some embodiments of the platform lift trailer  1100  provide a very compact configuration that is especially more compact in an unloaded storage position, as shown in  FIG. 22 . Also, as noted above, caster wheel assembly  1400  is positioned to swivel 360° within and between and/or within the hitch tongue assembly  1300  and the travel path of platform  1520  of the lift assembly  1500 . This configuration allows full swiveling of the caster wheel(s)  1440  while maintaining the very compact overall design. 
     Further embodiments of the present invention are shown in  FIGS. 25-31 , in which a platform lift trailer  1600  is mounted to a motor vehicle  70 . A mounting assembly  1700  includes a hitch tongue assembly having a hitch tongue  1710  with an angular adaptor  1720  that permits some lateral angular adjustment. A mobility device lift  1900  is mounted to the hitch tongue assembly with a pair of brackets  1730 ,  1740 . Bracket  1730  is crescent-shaped to permit adjustability as to the angle of a mounted lift  1900  as well as its height. 
     The crescent shape of bracket  1730  includes a somewhat vertical branch  1732 , a horizontal branch  1734  and a bend  1736  connecting the vertical and horizontal branches  1732 ,  1734 . Horizontal branch  1734  has a mounting hole near its end for coupling the lower corner of triangular bracket  1740 , as seen in  FIG. 30 . As seen in  FIGS. 26 ,  28  and  30 , the somewhat vertical branch  1732  of bracket  1730  has a plurality of holes  1737  that permit another corner of bracket  1740  to be affixed in an adjustable manner, as will be appreciated by those skilled in the art. The bend  1736  of bracket  1730  holds an axle  1750  for one or more caster wheels  1800 . Bracket  1740 , in addition to having bracket  1730  mounted to it, also has the lift device  1900  affixed to two or more points on bracket  1740 , as seen in  FIG. 30 . Lift device  1900  has a mounting bracket  1930  that typically is used to mount the device to any supporting structure. 
     Lift  1900  uses only vertical motion, provided by actuator system  1910 , to raise and lower lift platform  1920 . Because a vertical-only lift device does not provide horizontal/lateral movement of platform  1920 , the lift must be mounted in a position allowing platform  1920  and the remainder of lift  1900  to stay clear of wheel  1800  and any other structure that might interfere with operation of lift  1900  and/or the caster-supported structure of caster-supported lift  1600 . In other embodiments, as noted above, a lift may have separate horizontal-motion apparatus to extend and retract platform  1920  and vertical actuator  1910 , as seen in various lifts common in the mobility device field. A number of lift devices are well known to those skilled in the art and can be used in connection with embodiments of the present invention. 
     The embodiments of  FIGS. 25-31  do not provide a swivel, per se, for any wheel(s)  1800 , though such accommodation can be made as will be appreciated by those skilled in the art. When a swivel structure is introduced to embodiments such as those shown in  FIGS. 25-31 , the additional required structure can add substantial undesirable length to the caster-supported apparatus (e.g., 48 inches or more). The lift platform  1920  in some embodiments can be folded in a manner analogous to that shown in  FIG. 22 . 
     The many features and advantages of the present invention are apparent from the written description, and thus, the appended claims are intended to cover all such features and advantages of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, the present invention is not limited to the exact construction and operation as illustrated and described. Therefore, the described embodiments should be taken as illustrative and not restrictive, and the invention should not be limited to the details given herein but should be defined by the following claims and their full scope of equivalents, whether foreseeable or unforeseeable now or in the future.

Technology Category: 7