Patent Abstract:
A cart pulling vehicle for use in parking lots made up of a hand operated motor-driven base which pulls shopping carts. The device utilizes a cable that is retractably mounted on the base and stretches to surround the line of carts pulled. This cable is retracted by a pair of cable drums at its ends which are driven by torsion springs. These separate dual torsion springs place torque on the cable drums which, in turn, exert tension on each half of the cable. When the cart pulling vehicle is in motion, a lock arrangement prevents additional cable from unreeling which the tension on each side cable pulling the carts in a train-like fashion. When the vehicle is stopped, a lock is released and the cable is able to extend to surround additional carts.

Full Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to a motorized vehicle for pulling shopping carts, and more particularly to a cart pulling vehicle with dual cable drums and dual torsion springs. 
     II. Discussion of the Prior Art 
     In the past, collection of shopping carts from parking lots was done by manual pushing of a string of carts by a store employee. As these carts were retrieved, the line of carts being pushed would grow longer and more difficult to maintain control. Two workers were required, one at the rear of the string to push and one at the front to steer. Therefore, the number of carts that were retrieved at one time was comparatively limited. Not only was this manual process time-consuming and manpower intensive, it was also a strenuous activity requiring physical strength and agility. 
     In response to the difficulty experienced in retrieving shopping carts, several motorized devices began to be utilized. One such device is disclosed in U.S. Pat. No. 6,220,379. This device is basically a small electrically powered cart which can be either driven or operated by remote control. The device uses a pushing from the rear technique. 
     Another, more closely related, prior art design uses a rope extending from a motorized vehicle to the last cart in a line to pull the carts in a train-like fashion. These prior pulling machines generally have two rope play-out and take-up drums on a common shaft and a single torsion reaction spring with a single lock mechanism. The lock mechanism is controlled by switch when the handle is placed in working position. A rope extends from one drum out the rear of the machine to a rope pull and is returned to the drum on the other side of the machine. This device allows the rope to  be free to extend or retract when the lock is engaged. Unfortunately, this design has a substantial number of problems. Because the single torsion spring is attached to both drums, tension is only provided to the side with the tightest length of rope. Often the other length of rope does not have enough tension to keep it from dragging on the ground, especially when rounding corners. While this problem is intended to be addressed with the pulleys, they prove to be only marginally effective due to friction and rotational resistance. The lack of tension on one side often causes the rope on that side to unspool from its drum. Torsion spring life also is a problem due to limited space on the machine, the fact that the spring is on a common shaft with the drums, and the large number of extend/retract cycles to which the machine and spring are subjected. Finally, the rope used is also a problem because the rope is heavy and bulky to withstand the load exerted by the carts and is vulnerable to the negative effects of rubbing. 
     Therefore, what is needed is the cart pulling vehicle of the present invention which effectively eliminates the requirements of physical strength and agility without the tension, torsion spring life, and rope problems of the past. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a cart pulling vehicle for use in parking lots everywhere. The cart pulling vehicle is made up of a hand-operated, motor-driven base which pulls shopping carts with a cable that is retractably mounted on the base and stretches to surround the line of carts being pulled. This cable is wrapped around a pair of cable drums at its opposite ends. Separate dual torsion springs for each drum place torque on the cable drums which, in turn, exert tension on the length of cable spanning each side of the string of shopping carts. A lock mechanism prevents the cable from unreeling when the vehicle is in motion while the tension of each side cable pulls the carts in a train-like fashion. When the vehicle is stopped, a lock disengages the cable tension and the cable is able to be pulled from the drums so that additional shopping carts can be added to the already assembled string of carts. 
     These and other objects, features, and advantages of the present invention will become readily apparent to those skilled in the art through a review of the following  detailed description in conjunction with the claims and accompanying drawings in which like numerals in several views refer to the same corresponding parts. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the cart pulling vehicle of the present invention; 
         FIG. 2  is a perspective view of the internal components of the cart pulling vehicle; 
         FIG. 3  is a top view of the cable routing layout and unassembled cable pull handle; 
         FIG. 4  is a side view of the cable pull handle; 
         FIG. 5  is a perspective view of the cart hitch used to couple the vehicle to the lead shopping cart; 
         FIG. 6  is a cross-sectional frontal view of the internal machine layout; 
         FIG. 7  is a partial side view of the internal machine parts; 
         FIG. 8  is a partial side view of the internal machine parts; 
         FIG. 9  is a cross-sectional view of the spring shaft assembly; and 
         FIG. 10  is a cross-sectional view of the drum shaft assembly. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention represents broadly applicable improvements for cart pulling vehicles. The embodiments herein are intended to be taken as representative of those in which the invention may be incorporated and are not intended to be limiting. 
     Referring first to  FIG. 1 , there is shown a side view of the cart pulling vehicle along with a string of nested carts to be transported by the vehicle. The assembly itself is indicated generally by numeral  10 . It includes a motor-driven base  12 , a cable reel cover  14 , a steering arm  16 , a vehicle motor control box  18 , a cart hitch assembly  20 , a cable  22 , cable routing pulleys  24 , cable guides  26 , a pull handle  28 , handle and guide storage bracket  30 , visibility flags  32 , and visibility beacon  34 . 
     With reference to  FIG. 2 , the cart pulling vehicle is seen in a perspective view with its cable cover  14  lifted, allowing a more detailed examination of the vehicle&#39;s internal features. The cable reel cover  14  is flipped open about a hinge and the internal components are exposed. The internal components include cable drums  36  and  38 ,  cable springs  40  and  42 , a first drum shaft  44  for the drum  36 , large sprockets  46 , outer sprockets  48 , and brackets  50 . All of these features are mounted above the motor-driven base  12  and contained within the cable reel cover  14 . In that the present invention is not directed to the dc motor drive for the vehicle&#39;s wheels, there is no need to describe these features. 
     Generally, the cable  22  wraps around the center spindle  52  of one of the drums  36 , extends out from opening  53  in the back of cover  14 , loops through pulley  24  on the vehicle&#39;s base, stretches around the collected shopping carts in a manner described more particularly below, back under the cover  14 , and around the center spindle  54  of drum  38 . The cable springs  40  and  42  are principally responsible for producing independent torque on each of the cable drums  36  and  38 , thus causing simultaneous tension pulling on both ends of the cable  22 . A more complete explanation of the working of these components will be discussed in detail later. 
     It is also possible to view some of the components of the motor-driven base  12  in  FIG. 2 , including its conventional battery, motor, wiring etc., although, as mentioned, these will not be discussed in detail. 
       FIG. 3  shows a top view of the cable routing layout and unassembled cable pull handle. This figure is intended to disclose a schematic of the locations where the cable  22  interacts with the various elements of the device. The cable  22  is preferably aircraft cable made of steel, but coated in plastic to reduce damage caused by the cable. The two looped and clamped ends  56  of cable represent the location where the cable ends mount on the flat side faces of the cable drums  36  and  38  before they are wound around the center spindles of the drums. Next, is a cable travel stop and limiter  58  which provides a contact point to stop the cable motion before the end of the cable is reached. The cable  22  then extends out from underneath the cable reel cover  14  and around the two pulleys  24  which are mounted near the bottom edge of motor-driven base  12 . Next, the cable wraps around the perimeter of the carts using the holes  60  in the two cable guides  26  to direct the cable&#39;s path. The cable guides  26  are mounted longitudinally across the open basket of a shopping cart near the cart&#39;s handle pushed by the consumer. These two guides can be placed on any carts which would enable a  more effective path around the cart perimeter. (See  FIG. 1 .) 
     The cable guides  26  are each comprised of a solid, metal rod which is roughly bent into a U-shape. The ends of the rod are curled back into loops  62  on both sides through which the cable  22  passes. Adjacent to the loops  62 , the ends extend up at an angle before straightening and bending at a right angle over the open basket of the shopping cart. When the rod approaches the center, it extends up into a further long and narrow U-shaped bend  64 . This design effectively fits over a shopping cart basket with a stable, yet easily movable, set of guides for cables stretching along the perimeter of a line of carts. 
     The cable  22  completes the loop around the perimeter of the carts by extending through a pull handle  28  that is adapted to be hooked to the handle on the rearmost shopping cart. This pull handle  28 , shown in exploded form in  FIG. 3 , comprises edge plates  66 , u-shaped couplers  68 , a handle member  70 , a bottom plate  72 , and pulleys  74 . 
     The pull handle  28  generally is a latching mechanism enabling the cable  22  to connect with the carts without significant frictional resistance. The pull handle  28  allows the cable to move from left to right to equalize tension. The pulleys  74  act as low friction bearings to ensure minimal movement of the cable. The pull handle  28  is attached to the last shopping cart in a line of pulled carts by hooking the curved couplers  68  over the shopping cart&#39;s handle. Because most forces will be directed contrary to this interaction, the curved coupler  68  typically bears most of the load directed by the carts. Between the curved couplers  68  is a large handle  70 . This handle enables the user to easily add carts to the end of the line, then to quickly move the pull handle  28  to the handle of the last shopping cart in the string. L-shaped edge plates  66  are also attached to the sides of the pull handle  28  so that it will not slide off the cart handle due to side-to-side forces. These forces can be caused during the moving of carts when a turn is made by the cart string. During turns, the extra cable required at the outside of the turn is pulled through the inside pulley of the pull handle  28 . The pulleys  74  of the pull handle  28  are placed at the front edges of the panel bottom plate  72 . On the top of the cable pull handle  28  is a visibility flag  32  ( FIG. 1 )  which is mounted by an angled bracket. This flag is intended to make the string of carts more easily recognizable to motorists in the parking lot. 
       FIG. 4  shows a side view of the pull handle assembly  28 . It is important to note that the cable  22  will extend around the pulleys  74  which are mounted within the front portion of the handle. Also observed here is the shape and configuration of the edge plates  66 , couplers  68 , handle  70 , and bottom plate  72 . 
     With reference to  FIG. 5 , a perspective view of a cart hitch  20  is shown. This hitch is generally a triangular-shaped piece of metal containing two C-shaped hooks  76  looping up from the sides of the base of the triangular metal piece. The apex of the triangle has a hole  78  through which a spring mounted bolt passes to an angled bracket  80  secured on the motor-driven base  12 . There is a second sheet metal piece  82  that forms a latch or detent. It is bolted to the middle of the hitch at a hole  84 . It angles up from its attachment before bending downward to form a blocking panel  86 . This panel is perpendicular to an opening  88  in the triangular piece and may be pushed down against the force of a return spring (not shown) positioned between the triangular plate and the detent  82 . When the blocking panel  86  is pushed down, the bottom bar of the first shopping cart in a line can be slid into the c-shaped hooks  76 . When the blocking panel  86  is released, the bottom bar of the shopping cart will be prevented from moving outside the confines of the c-shaped hooks  76 . The action of holding the first cart allows steering of the other carts as long as each cart in the string remains nested into the cart preceding it. The cart hitch  20  is spring loaded by axially mounting a spring  90  on a bolt  91  extending through angle plate  80  and hole  78  in the triangular plate. This allows the cart to be slightly above or below the hitch connection to the pulling machine during driving over uneven ground. 
     Also, seen in  FIG. 5  is a more detailed perspective of the pulleys  24  which are used to route the cable  22  as it comes out from underneath the cable reel cover  14 . Routing the cable downward from the cable drums  36  and  38  and around pulleys  24  helps to prevent lifting of the drive wheels of the cart pulling vehicle. Directing the forces downward in this way provides greater traction than if the cable were routed directly from the drums  36  and  38  to the pull handle.  
       FIG. 6  shows a cross-sectional frontal view of the internal machine layout. In the figure, mounting brackets  50  are bolted to each side of the motor-driven base  12 . These brackets are roughly U-shaped pieces of sheet metal with legs which bolt to the base  12  and have a hole  92  centrally located. Bearings  94  are placed within holes  92  of the mounting brackets  50 . Axially mounted though the bearings  94 , on each side of the assembly, are drum shafts  44 . The two drum shafts  44  are axially aligned, although each shaft extends about one-third of the width of the assembly with a gap in between. (See  FIG. 10 ) The shafts are additionally supported on bearings  96 , which are held in place by another set of brackets  98 . Shafts  44  contain square keys which protrude slightly out from their circumference. This feature allows for a locked connection with the sprockets  100  and drums  36  and  38  which are axially engaged around the keyed shaft  44 . 
     Sprockets  100  and cable drums  36  and  38  are axially mounted on the drum shaft  44  between the bearings  94  and  96 . The sprockets  100  have a plurality of teeth and are critical components of the locking mechanism of the assembly. (See  FIG. 7 .) The cable drums  36  and  38  comprise a pair of circular flanges on each side of a spindle  52 ,  54  on which the cable  22  is wound. The outside flat surface flanges of the drums contain a bolt  102  onto which the ends of the cable  22  are secured. One end of the cable is affixed to the outside of the first cable drum  36  and the other end mounted on the outside of the second cable drum  38 . The center hole of these cable drums and sprockets  100  are all adapted to axially engage around the keyed drum shafts  44 . (see  FIG. 7 ) 
     Looking again at  FIG. 6 , a smaller diameter sprocket  104  is mounted on each of the drum shafts  44 , just inside the location of the cable drums  36  and  38 . These sprockets  104  have a keyed center mount and are transversely aligned with sprockets  106 . A drive chain  108  (not shown) is engaged around both sprocket  104  and sprocket  106 . (see  FIG. 8 ) 
     Sprockets  106  are both part of the spring shaft assembly. These sprockets  106  are located on opposite sides of the assembly from one another and are displaced vertically from one another. Sprockets  106  have keyed center holes  110 . It is  important to note that while the center axis of the two holes  110  are simply vertically displaced from one another, these are both vertically and horizontally displaced from the axis that runs through the center of drum shaft  44  (see  FIG. 8 ). Sprockets  106  serve to rotate spring shafts  112 . These spring shafts  112  span the gap between the two brackets  98  and are rotationally mounted within bearings  114  in each side of bracket  98 . Inside the confines of the brackets  98 , there are hub  116  and  118  on each side of the shaft  112 . The hubs each contain a hole into which an end of the spring  40  or  42  is fit. The hub  116 , on the side furthest from the sprocket  106 , is bolted into place and remains non-rotatable. The hub drive  118 , nearest the sprocket  106  has its center hole keyed to the spring shaft  112  and is capable of being rotated, causing the shaft  112  to rotate when the sprocket  106  is driven. This serves to store energy in the spring. There is a hollow spring support tube  120  extending between the ends of the hub drives  116  and  118 . Springs  40  and  42  encircling the spring support tubes  120 . These springs are the mechanisms responsible for generating the required tension in the cable  22  for securing the shopping carts. (See  FIG. 9 ) 
     Also seen in  FIG. 6  are braces  122  and  124 , which generally are metal bars that run longitudinally between the brackets  98  near the top and bottom of the spring shaft assembly. These braces  122  and  124  are attached with bolts through their angled ends. They generally provide increased stability and support to the assembly. 
     Now referring to  FIG. 7 , a partial inside side view of internal machine parts is shown. This figure discloses a excellent perspective of the cable attachment to drum  36  and cable routing under the cable reel cover  14  and around pulley  24 . This figure also shows the outline of one of the brackets  50  upon which the drum shaft  44  is centrally mounted. A cable drum lock  126 , used to engage with the sprocket  100  to halt cable movement when the vehicle is in motion is seen here as well. This cable drum lock  126  is solenoid controlled by an electric motor driver that provides a signal which the circuit uses to control the lock and unlock action of a locking pawl. 
     Now referring to  FIG. 8 , a partial inside side view of internal machine parts is shown. This figure discloses a cross-section of parts seen if one were to hypothetically remove the nearest cable drum and support bracket of  FIG. 7 . This is a useful cross-section  denoting the locations of the axis of both spring shafts  112  as well as the drum shaft  44  and the chain linking the two. A side view of bracket  98  is also disclosed. The bracket  98  contains three shaft openings for the spring and drum shafts. The openings for the spring shafts are rounded horizontal slots into which shafts are inserted, and the drum shaft opening is a centrally located hole. 
       FIG. 9  shows a cross-sectional view of the spring shaft assembly. The figure discloses a shortened spring  40  which enables view of the end fittings. Also seen here is how the end of the shaft nearest the hub drive  118  uses a square key fitting  128 . In the actual assembly of the cable drum and tensioning mechanism, there are two spring shaft assemblies of the type illustrated in  FIG. 9 . One of these assemblies is turned 180 degrees and is mounted above the other. Because the spring assemblies are on discrete shafts that overlap in spanning the width dimension of the vehicle, the vehicle can be of a reduced width allowing it to be no wider than the shopping carts being pulled. This allows easier passage through doors of the commercial establishment. Where a wider cart profile can be tolerated, the cable springs  40  and  42  can be mounted on the same shaft as an associated drum  36  and  38 . That is, spring  42  can be mounted on shaft  44  on which drum  36  is offered the shaft supporting cable spring  40 . In this way, the chains and sprockets can be eliminated. 
       FIG. 10  is a cross-sectional view of the drum shaft assembly. In this device there are two drum shaft assemblies like the one shown. One is turned 180 degrees from the one shown in  FIG. 10 , but the axis of both of the drum shaft assemblies are aligned axially. 
     The operation of the cart pulling vehicle with dual cable drums and dual torsion springs is as follows. First, an operator first moves the cart pulling vehicle into the parking lot to the location of a shopping cart using the handle controls  18  which lead to the motor that drives the cart. The pull handle and cable guides are initially held on the handle guide and storage bracket  30 . The first cart is attached by inserting the cart&#39;s lower bar in the c-shaped hooks  76  of the cart hitch  20 . All additional carts are stacked into a line by partially nesting the basket of one into the cart in front of it. Next, the cable pull handle  28  is extended and hooked on the handle of the last cart in  the line. Cable guides  26  are placed across the baskets of some of these carts to ensure the cable encircles the carts with a minimum of contact with the sides of the carts. Once the propelling machine has surrounded a variable number of carts with a cable  22 , the vehicle control is activated by the operator to move the vehicle. The locking solenoid device  126  locks the drums  36  and  38 , preventing playout of the cable  22  as the machine moves the carts to a new location. Once the machine has stopped, the solenoid latch  126  is released to allow the cable to be pulled from the drums so that carts can be added or removed. The operator has the ability, at any time the machine is not moving, to move the cable in or out with little effort based upon the spring design. The attachment and design of the cable guide  26  and cable pull handle  28  allows addition of carts without moving the cable pull handle  28  until after the carts have been added. Additional controls allow locking the cable so that the cable drum lock does not disengage when the machine has stopped. This feature provides additional control of the cart motion for the operator when moving the machine, device and carts from the collection area of the parking lot to the use or storage areas. 
     This invention has been defined herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself

Technology Classification (CPC): 1