Abstract:
A portable vehicle lift employed by lifting at a wheel assembly, which lift comprises a base, a stand extending vertically upward from said base, a carriage being mounted for vertical movement on said stand, said carriage further comprising a pair of arms with forwardly protruding cradle members at the bottom of said arms, an engagement pad on the front of said carriage to bias said lift against the rim of said wheel assembly, and a lift mechanism for extending the combined length of said stand and said carriage. The arms may be adjustable in width to function with a variety of wheel assembly sizes. The inclusion of the engagement pad on said carriage provides contact with the wheel assembly, thereby biasing the lifting device with the tilting force due to leverage forces of the weight of the wheel assembly on the outwardly projecting cradle members. Biasing the lifting device with the engagement pad provides stability on a compact base, such that said base need not extend more than a limited distance outwardly from the front of the stand.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application 60/399,644 filed Jul. 31, 2002. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     This invention relates generally to transportable lifts for automobiles, and more particularly to an apparatus for lifting a vehicle and supporting the vehicle at the lifted position.  
         [0005]     2. Description of the Related Art  
         [0006]     Maintenance of vehicles such as automobiles and trucks requires access to the underside of the vehicles in order to permit repair or alteration of parts, such as wheel assemblies, suspension, transmissions, brakes and the like. In order to access such areas, a mechanic will typically employ one or more lifting devices in concert or sequentially to move part or the entire vehicle to a raised position.  
         [0007]     Once the vehicle has been raised to a desired height for access, rigid stands may be positioned beneath the vehicle to support it and the lifting devices may be removed. Such rigid stands are used because rigid stands provide better support and do not permit vertical shifting of the vehicle.  
         [0008]     Vehicle lifts, which typically lift the vehicle frame, may create several problems. Typical lifting devices apply lifting force to the vehicle frame. Use of lifting devices may be impeded or prevented due to the location of the lifting point relative to the exterior of the vehicle as well as the clearance between the ground and the frame due to vehicle construction, vehicle suspension modification, ground effects or the like. Lifting the vehicle from a point other than an appropriate lifting point may cause damage to vehicle components. Lifting the vehicle at the frame may damage ground effects structures, which extend downward from the body to a point below the frame. It may also damage the appearance of the frame or undercarriage in cases where a pristine frame or undercarriage is desired.  
         [0009]     As an alternative to vehicle lifts, a vehicle lift that contacts the lower portion of the tire-and-wheel assembly may be used. Lifting the vehicle from the tire-and-wheel assembly provides an additional benefit where the vehicle is particularly close to the ground and there is little space for insertion of a lifting device. Lifting the vehicle from the tire-and-wheel assembly more quickly provides additional clearance, as there is no delay while the suspension travels to its maximum deflection and requires less travel by the lifting device. Such tire-and-wheel lifting devices typically employ a fork to engage to the front and rear of the tire-and-wheel assembly, such that the tire-and-wheel assembly has relatively even pressure on both the front and rear half, so it will not have a tendency to roll off the tines of the fork.  
         [0010]     Both such vehicle lifts may be permanently mounted or may be portable. The use of portable vehicle lifts is essential for persons performing such work outside of a professional garage. Often times portable vehicle lifts include a base too large to be inserted under a vehicle, which is close to the ground. A large base is intended to prevent the lift from tilting during vehicle lifting.  
         [0011]     Tire-and-wheel assembly engaging vehicle lifts are known in the art. U.S. Pat. No. 5,954,160, issued to Wells, Sr., et al. on Sep. 21, 1999, discloses a tire-and-wheel assembly engaging lift for raising the entire vehicle comprising, inter alia, a pair of arms, each ending in a set of tire-and-wheel assembly engaging adapters, pivotally attached to a vertically-adjustable carriage wherein each arm may be elongated and adjusted so each fork may engage the lower exterior of the respective tire-and-wheel assembly. U.S. Pat. No. 5,911,408, issued to Berends et al. on Jun. 15, 1999, discloses a transportable lift for raising a single tire-and-wheel assembly of a vehicle, comprising, inter alia, a stand, a carriage having a set of forks attached to said stand capable of vertical movement, a base having transporting wheels and a forward extending section adjacent the forks and a means to disengage the transporting wheels. U.S. Pat. No. 5,484,134, issued to Francis on Jan. 16, 1996, discloses a vehicle lift and stand comprising, inter alia, a base having a vertical post and a forward extending section surrounding the edges of the tire-and-wheel assembly, a cylinder mounted on said vertical post with a piston and cylinder means for moving a tire-and-wheel assembly cradle, a pawl and ratchet system for restricting motion to the intended direction only, and a means to lock the carriage at a particular height comprising a pin though a hole in the post. U.S. Pat. No. 5,184,930, issued to Kuhn on Feb. 9, 1993, discloses a system for lifting a vehicle comprising, inter alia, two jacks, two carriages mounted on posts, each carriage engaging one tire-and-wheel assembly with a fork, each post having a forward extending section surrounding the edges of the tire-and-wheel assembly, and a system to power said jacks. U.S. Pat. No. 3,647,183, issued Mar. 7, 1972 to Rishovd, discloses a system for raising a vehicle comprising, inter alia, a lift member on a vertical column having teeth to engage a pawl for restricted up or down motion, a valve to drive a piston and cylinder assembly to vertical motion and a base having a forward extending section surrounding the edges of the tire-and-wheel assembly.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012]     The present invention overcomes shortcoming of the prior art regarding portability and use with vehicles by providing an improved portable vehicle lift without the need for a forward extending section. The invention comprises a base, a stand extending vertically upward from said base, a carriage mounted for vertical movement on said stand, said carriage further comprising a pair of adjustable arms, each having a cradle member extending outwardly, normal to the stand and carriage, and an engagement pad at the top front of said carriage for engaging said vehicle&#39;s tire-and-wheel assembly, a lifting apparatus for imparting vertical motion between said stand and said carriage, and a lift lock for fixing the vertical position of said carriage in relation to said stand. The carriage arms may be adjustable in width to function with a variety of tire-and-wheel assembly sizes. The engaging pad at the top front of said carriage provides biasing with the tire-and-wheel assembly, thereby preventing the lifting device from tilting, as vehicle weight is assumed by the lift. Engagement of the lifting pad with the tire-and-wheel assembly provides stability and, as part of a system, eliminates the need for a large base, thereby reducing the portable vehicle lift&#39;s weight and size, and making the lift operable in a greater variety of conditions. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a rear view of an embodiment of the portable vehicle lift in the lowered position.  
         [0014]      FIG. 2  is a side view of an embodiment of the portable vehicle lift in the lowered position.  
         [0015]      FIG. 3  is a front view of the lift of  FIG. 1 .  
         [0016]      FIG. 4  is a partially cut-away rear view of the vehicle lift of  FIG. 1 .  
         [0017]      FIG. 5  is a segment of a partially cut-away rear view of the vehicle lift of  FIG. 1 , with the lifting apparatus in an extended position.  
         [0018]      FIG. 6  is a rear view of the lift of  FIG. 1 , in a raised position.  
         [0019]      FIG. 7  is a front view of an alternate embodiment of the portable vehicle lift. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0020]     In  FIGS. 1-4 , a portable vehicle lift  10  according to the present invention is shown in relationship to a wheel assembly  1 . Though usage of the terms tire and wheel vary in the field, for the purposes of this disclosure a wheel assembly I is comprised of a rigid, typically metal, central mounting structure referred to as a rim  3 , which in most cases has mounted thereon a tire  2 . The portion of wheel assembly  1  that comes in contact with the surface upon which the wheel assembly sits is the contact area  6 . Contact area  6  extends from the inside to the outside of wheel assembly  1 , and extends a partial distance to the circumferential front and to rear wheel assembly  1 .  
         [0021]     Portable vehicle lift  10  comprises a base  12  of sufficient area to support the load to be lifted by lift  10 . In most instances the use location will have a solid or hard packed surface, suitable for vehicular traffic. As such, the area required by base  12  can be similar to conventional vehicular jacks. The area of base  12  is defined by the length of base width  20  and the length of base depth  21 . The combination of base width  20  and base depth  21  are sufficient to provide an adequate area for lifting the weight of a portion of a vehicle without lift  10  sinking into surface  5  when carrying the intended portion of a vehicular weight carried by wheel  1 .  
         [0022]     A stand  13  extends upward from base  12 . Stand  13  attaches to base  12  to restrict motion between stand  13  and base  12  while weight is applied. In the exemplary embodiment, base  12  is fixed to stand  13 , and base  12  is rectangular, occupying only a slightly larger area than the bottom end of stand  13 .  
         [0023]     A carriage  14  is mounted to stand  13  for vertical movement on stand  13 . Referring to  FIGS. 5 and 6 , stand  13  possesses a lift mechanism  15 , which may be selective operated to extend the combined length of stand  13  and carriage  14 . In the exemplary embodiment, carriage  14  is a sleeve structure that surrounds part of stand  13  from the end opposite base  12 . Additionally, exemplary stand  13  is a hydraulic drive cylinder, having a cylindrical drive housing  31  and a drive rod  53 . Exemplary carriage  14  has a square cross-sectional shape, with an interior width slightly greater than the cross-sectional diameter of stand  13 . Stand  13  has guide blocks  30  affixed to the outside surface of stand  13 , directly between stand  13  and carriage interior wall  42 . Guide blocks  30  are positioned to provide a stable relationship between the position of stand  13  and carriage  14 . The exemplary embodiment has four guide blocks  30  oriented at the corners of carriage interior wall  42 , and shaped to fill the void between the round shape of stand  13  and the square shape of carriage  14 .  
         [0024]     Referring to  FIGS. 1-4 , carriage  14  has a front  45 , a back  46 , a top  41  and two opposing carriage sides  44 . Carriage top  41  is located distal base  12 . Carriage front  45  is the face of carriage  14  intended to be closest to wheel  1  during operation. The opposing face to carriage front  45  is referred to as carriage back  46 . The opposing faces connecting front  45  to back  46  are carriage sides  44 .  
         [0025]     Affixed to carriage front  45  is an engagement pad  17  for interfacing with a wheel  1  to be lifted. Engagement pad  17  is positioned on carriage front  45  such that when lift  10  is in a lowered position, shown in  FIGS. 1-3  and  5 , and positioned adjacent to wheel  1 , engagement pad  17  comes in contact with rim  3 . The extent to which base depth  21  extends outwardly from lift  10  is limited so as to permit the positioning of engagement pad  17  in contact with rim  3  when lift  10  is positioned adjacent to wheel  1  for use. Engagement pad  17  is constructed of a dense, resilient, non-abrasive material. In the exemplary embodiment, engagement pad  17  contacts rim  3  at the upper end near the interface of rim  3  and tire  2 , as shown in  FIG. 2 . In the exemplary embodiment engagement pad  17  is rubber.  
         [0026]     The area immediately adjacent to lift  10  on the side of carriage front  45  is wheel receiving space  7 . Wheel receiving space  7  has the physical dimensions of a wheel assembly  1  upon which lift  10  may be applied. The face of engagement pad  17  distal carriage  14  defines the closest plane of the wheel receiving space  7 .  
         [0027]     Base  12  may extend a short distance outwardly from vehicle lift  10  toward wheel receiving space  7 , however, base  12  does not encroach on wheel receiving space  7 . Engagement pad  17  may extend a short distance outwardly from carriage  14  toward wheel receiving space  7 . The distance to which base  12  extends toward the front of lift  10  does not essentially exceed the distance to which pad  17  extends toward the front.  
         [0028]     In the exemplary embodiment of  FIG. 2 , a handle  11  is shown affixed to carriage back  46  adjacent carriage top  41 . Referring to  FIGS. 1-5 , on the side of base  12  corresponding with carriage back  46  are wheels  23 , attached by wheel mounts  22 . In the exemplary embodiment there are two wheels  23  in order to provide appropriate stability to lift  10  when tilted by handle  11  onto wheels  23 .  
         [0029]     Referring to  FIGS. 1-4 , carriage  14  further comprises a wheel-engaging adapter  62 . Wheel-engaging adapter  62  is positioned to be proximate wheel receiving space  7  in order to support a wheel assembly  1  from the bottom. In the exemplary embodiment, wheel-engaging adapter  62  is formed by a pair of arms  16 , one on each carriage side  44 , which arms  16  are hingedly attached to carriage sides  44  at one end by arm mounts  61 , such that arms  16  may be positioned at angles to stand  13  within a movement path ranging from parallel in a downward position to parallel in an upward position. Exemplary arm mounts  61  are comprised of front hinge plate  66 , back hinge plate  67  and hinge pin  68 , as seen in  FIG. 2 . Each exemplary arm  16  has a cradle member  63 . Cradle members  63  are attached to exemplary arms  16  distal to arm mounts  61 , and extend outwardly from carriage front  45 , and perpendicular to carriage front  45 . In the exemplary embodiment, cradle members  63  are rigidly fixed to arms  16 . In an alternate embodiment (not shown), cradle members  63  may be hingedly attached to arms  16  in order to provide for folded storage against arms  16 . The distance between cradle members  63  and engagement pad  17  must be of appropriate length so that during operation of lift  10  engagement pad  17  contacts rim  3  while each of cradle members  63  are in contact with the rolling surface at opposing sides of contact area  6  of wheel assembly  1 .  
         [0030]     The length of contact area  6  is determined by a particular wheel assembly  1 . A larger diameter wheel assembly  1  has a longer contact area  6  and a wider wheel assembly  1  has a wider contact area  6 . Arms  16  may be of sufficient length to accommodate a variety of wheel assembly  1  sizes. Cradle members  63  may be of sufficient length to accommodate a variety of wheel assembly depths  4 .  
         [0031]     Arms  16  abut backing bar  26 , which is permanently mounted to carriage  14  below the level of arm mounts  61 . Backing bar  26  has generally horizontal backing bar holes  64 , through which backing bar pins  65  may be inserted to extend into the movement path of hinged arms  16 , limiting the upward and outward movement of arms  16 . Backing bar  26  attaches to carriage  14 , extending outwardly normal to carriage  14 , immediately adjacent the movement paths of arms  16 . Backing bar  26  may provide lateral support to arms  16 , such that arms  16  are reinforced against forces that would push arms  16  laterally past carriage back  46 . In the exemplary embodiment, backing bar  26  is permanently attached coplanar to carriage back  46 , extending outwardly beyond each carriage side  44 .  
         [0032]     Lift mechanism  15  may be configured using various types of lifting mechanisms known to the field to apply extending force between stand  13  and carriage  14 . The exemplary lift mechanism  15 , emphasized in  FIGS. 5 and 6 , employs a hydraulic drive cylinder having the drive housing  31  integrated into stand  13 . Drive rod  53  protrudes from the end of stand  13  distal base  12  to contact carriage top interior  43 . The protruding portion of drive rod  53  has a rod hole  55 , which is alignable with rod pin holes  47  in each carriage side  44 , distal base  12 . Rod pin  48  is provided to extend through rod pin holes  47  and rod hole  55  securing drive rod  53  to carriage  14 . Rod pin  48  is retained in rod pin holes  47  and rod hole  55  by a cotter pin  56  or other means known to the field.  
         [0033]     In the exemplary embodiment, lift mechanism  15  has a lift actuator  50 , which cooperatively operates with a lift lever  52 . Lift lever  52  extends outwardly from stand  13  from the face corresponding to carriage back  46 .  
         [0034]     Alternatively, the hydraulic drive cylinder may be external to the stand. Alternative types of lifting mechanisms  15  include screw configurations, scissors configurations and pawl-and-ratchet jack configurations, which would apply separating force between stand  13  and carriage  14 .  
         [0035]     Referring to  FIG. 7 , an alternate exemplary embodiment of vehicle lift  10  has an alternate configuration of wheel-engaging adapter  62 . Arm  16  is comprised of a single piece fixed to carriage front  45 . Cradle members  63  are attached to the opposite ends of exemplary arm  16  from engagement pad  17 , and extend outward from the carriage front  45  and perpendicular to the carriage front  45 . The distance between cradle members  63  and engagement pad  17  must permit engagement pad  17  to contact rim  3  while cradle members  63  are in contact with the underside of wheel assembly  1 .  
         [0036]     Referring generally to  FIGS. 1-6 , in operation, a user manipulates portable vehicle lift  10  into the lowered position, with carriage  14  lowered close to base  12 , arms  16  angled slightly away from stand  13  and cradle members  63  proximate to solid surface  5 . In this lowered position, lift  10  is moved adjacent wheel assembly  1 , with carriage front  45  facing wheel assembly  1 . Lift  10  is oriented with base  12  positioned on solid surface  5 , adjacent to the contact area  6  of wheel assembly  1 , and engagement pad  17  in contact with rim  3 . Cradle members  63  extend under opposing sides of wheel assembly  1 .  
         [0037]     The distance to which base  12  extends toward the front of lift  10  does not essentially exceed the distance to which pad  17  extends toward the front. As such, pad  17  will not extend past the vertical plane of a wheel assembly  1 , upon which lift  10  is acting, and base  12  will not extend under said wheel assembly  1 , or around said wheel assembly  1  and under a vehicle (not shown) upon which said wheel assembly  1  is mounted.  
         [0038]     To raise wheel assembly  1  and a part of the weight of a vehicle (not shown) attached thereto, lift mechanism  15  is operated to extend the combined length of stand  13  and carriage  14 . In the exemplary embodiment, lift lever  52  is pumped upward and downward to move lift actuator  50  in a similar fashion, but with more mechanical advantage. Lift actuator  50  causes drive rod  54  to extend from the top of stand  13  and push against top interior  43  of carriage  14 , causing carriage  14  to extend linearly above stand  13 .  
         [0039]     The upward motion of carriage  14  forces upward motion in arm mounts  61 , arms  16  and cradle members  63 . As cradle members  63  travel upward, they contact and push upward against wheel assembly  1 . The weight of wheel assembly  1  and its accompanying vehicle (not shown) and the friction of the roadway surface of wheel assembly  1  against cradle members  63  fix arms  16  at the current angles in relationship to sides  44 . As lift mechanism  15  further extends the combined length of stand  13  and carriage  14  wheel assembly  1  is lifted off solid surface  5 . As the weight of wheel assembly  1 , being displaced away from the body of lift  10 , applies leverage forces on lift  10  such that the top of lift  10  pushes toward wheel assembly  1 . Engagement pad  17  is biased by the force of torque against solid rim  3  and the force of the weight on base  12 . The biasing forces cause lift  10  to maintain a stable upright position. With the exemplary embodiment, engaging pad  17  is biased against rim  3  and not excessively against tire  2 , since engagement of exemplary engaging pad  17  exclusively with tire  2  may result in sufficient force against the side of tire  2  to deform tire  2  to the point of breaking the bead between tire  2  and rim  3 .  
         [0040]     Lift mechanism  15  is raised until wheel assembly  1  reaches the desired height, after which time a stationary stand (not shown) may be placed under wheel assembly  1 , the axle upon which wheel assembly  1  is mounted or under an appropriate support point of a vehicle upon which wheel assembly  1  is mounted. Once a stationary stand is in place, lift mechanism  15  may be reversed to reduce the combined length of stand  13  and carriage  14 , taking the weight of wheel assembly  1  off lift  10 . Then lift  10  may be removed from its location adjacent to wheel assembly  1 . The lifting process may be repeated for multiple wheel assemblies  1  of a single vehicle.  
         [0041]     To lower the vehicle or individual wheel assembly  1 , vehicle lift  10  is manipulated into a raised position, where cradle members  63  are at a level lower than the bottom surface of the fore and aft portions of wheel assembly  1 . Lift  10  is again place immediately adjacent wheel assembly  1 , such that cradle members  63  are centered fore and aft of wheel assembly  1 . Lift mechanism  15  is operated to raise cradle members  63  to contact wheel assembly  1 , and for engagement pad  17  to engage rim  3 . Lift mechanism  15  is operated to extend the combined length of stand  13  and carriage  14  until the weight of wheel assembly  1  is on lift  10  and stationary stands are free from the weight of the vehicle.  
         [0042]     At this point stationary stands may be removed and lift mechanism  15  may be reversed, such that operation of lift mechanism  15  reduces the combined length of stand  13  and carriage  14 . This motion may be continued until the entire weight of wheel assembly  1  is supported by solid surface  5 , and lift  10  no longer supports any of the weight of wheel assembly  1  or its accompanying vehicle (not shown). Lift  10  may then be removed from its location adjacent to wheel assembly  1 .  
         [0043]     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.