Abstract:
A collector shoe assembly for use with an electrified conductor rail is disclosed. A support block comprised of first and second housing members secured together which has a plurality of spaced-apart, spring-loaded collector shoe segments movably positioned therein, the outer ends of which are in engagement with the conductor rail.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a collector shoe for use with an electrified conductor rail. More particularly, this invention relates to a segmented collector shoe assembly which includes a plurality of individually sprung collector shoe segments. 
     2. Description of the Related Art 
     Current collector shoe designs consist of a rigid collector shoe assembly mounted to a spring loaded arm. The arm is constructed such that it allows the shoe assembly to follow the conductor rail profile and adjust variations from parallel that the conductor rail may have relative to the running rail. These collector shoes are sized to have the appropriate amount of surface contact with the conductor rail to carry the electrical current required. Often they are sized for several hundred of amperes resulting in a long length of shoe. 
     A conductor rail cannot be manufactured perfectly straight and in some cases is required to be curved to follow the required path of the motorized equipment. When two rigid dissimilar surfaces are in contact, they will contact at the minimal number points to cause stability. Three points of contact are the minimum required for stability. The three points of contact are then subjected to a very high electrical current density causing each point to generate large amounts of heat. The heat then causes damage to the conductor rail and collector shoe ultimately resulting in shoe failure. This problem is particularly bad in installations where the equipment sits stationary for a period of time while drawing power. 
     A common current solution is to install multiple shoes along the rail to provide more points of contact to the conductor rail. This solution is undesirable because each shoe requires an additional mounting arm to be mounted to the equipment resulting in collector assemblies that grow incrementally in length for each collector that is installed. The long assemblies result in uneven load sharing between collectors. Also, the long collector assemblies reduce the amount of conductor rail length that can be used for movement because the space is occupied by collectors. Finally, the cost of the collector assembly is incrementally increased by the number of collectors installed. 
     Another problem with a rigid collector shoe is noted when it is used for signal or communication transmission while in motion. The three points of contact that were described above will continuously move from point to point and change along the collector shoe while the shoe is in motion along the conductor rail. Occasionally, as the collector shoe passes a joint in the conductor bar or even a spot of contamination or debris on the rail, the collector shoe resistance over the contact surface to the rail will rise to a point that the low voltage signal will not pass momentarily. This loss of signal can result in errors or faults between the equipment controls and drives. The typical solution is to install multiple shoes for redundancy. The intent being that at least one shoe will be making contact at any given time. The same undesirable characteristics of the multiple shoe solution apply to this situation as discussed hereinabove. 
     SUMMARY OF THE INVENTION 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     A segmented collector shoe assembly is described for use with an electrified conductor rail. The collector shoe assembly includes an elongated, generally rectangular, support block having a first end, a second end, a first side, a second side, an inner end, and an outer end. A plurality of electrical collectors are movably positioned in the support block in a spaced-apart aligned parallel manner. Each of the collectors has an inner end, an outer end, a first end, a second end, a first side, and a second side. A spring is associated with each of the collectors to yieldably urge the respective collector outwardly from the support block so that the outer end of the collector will be yieldably urged into sliding conductive engagement with the conductor rail. 
     In the preferred embodiment, each of the collectors has a generally rectangular cross-sectional configuration with the outer ends of the collectors being beveled. In the preferred embodiment, the support block has a plurality of spaced-apart collector compartments formed therein with the collectors being slidably mounted in the collector compartments. In the preferred embodiment, the collector shoe includes structure which limits the outward movement of the collector with respect to the support block. In the preferred embodiment, the support block is comprised of first and second housing members which are secured together in a snap-fit manner. 
     It is therefore a principal object of the invention to provide a segmented collector shoe assembly. 
     A further object of the invention is to provide a collector shoe assembly for use with an electrified conductor rail wherein the collector shoe assembly includes a plurality of segmented collector shoes which are aligned in a parallel fashion. 
     A further object of the invention is to provide a collector shoe assembly for use with an electrified conductor rail wherein a plurality of collector shoe segments are movably mounted in an elongated support block with each of the collector shoe segments being sprung outwardly with respect to the support block for engagement with the conductor rail. 
     A further object of the invention is to provide a segmented collector shoe assembly wherein the collector shoe segments are connected to a bus bar support block. 
     A further object of the invention is to provide a segmented collector shoe assembly which is easily mounted to a standard spring-loaded arm with the arm being secured to the mobile unit. 
     A further object of the invention is to provide a segmented collector shoe assembly which permits multiple contact points per collector shoe segment. 
     A further object of the invention is to provide a segmented collector shoe assembly wherein the same amount of current may be evenly distributed over many more contact points and in the same amount of space as a rigid collector shoe design. 
     A further object of the invention is to provide a segmented collector shoe assembly which distributes the current flow through many contact points which result in less heat produced at each point. 
     A further object of the invention is to provide a segmented collector shoe assembly which prevents damage of the shoes and conductor rail. 
     A further object of the invention is to provide a segmented collector shoe assembly which will provide low voltage to be transmitted along the conductor rail. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  is a perspective view of a prior art collector shoe assembly; 
         FIG. 2  is a perspective view of the segmented collector shoe assembly of this invention; 
         FIG. 3  is an exploded perspective view of the collector shoe assembly of this invention; 
         FIG. 4  is a partial sectional view of the collector shoe assembly of this invention; 
         FIG. 5  is a partial sectional view illustrating the manner in which the collector shoe assembly of this invention is attached to a spring-loaded arm which is secured to the vehicle; 
         FIG. 6  is a perspective view of one form of the collector shoe segment of this invention; 
         FIG. 7  is a perspective view of another form of the collector shoe segment of this invention; 
         FIG. 8  is a partial sectional view illustrating the prior art collector shoe assembly in contact with a conductor rail; and 
         FIG. 9  is a sectional view similar to  FIG. 8  except that the collector shoe assembly of this invention is illustrated. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments are described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense in that the scope of the present invention is defined only by the appended claims. 
     In  FIG. 1 , the numeral  10  refers to a prior art collector shoe which is urged into electrical contact with an electrified conductor rail  12  such as used on mobile units or vehicles such as a trolley, crane, conveyor, hoist, train, etc. The collector shoe  10  may slidably and electrically engage the underside of the conductor rail  12  or either side thereof. The collector shoes of the prior art and the collector shoe of this invention are urged into contact with the conductor rail  12  by the prior art mounting structure or spring arm  14  which is attached to the mobile unit or vehicle in conventional fashion. 
     The collector shoe assembly of this invention is referred to by the reference numeral  16 . Assembly  16  includes an elongated, generally rectangular-shaped housing member  18 . Housing member  18  includes a first end  20 , a second end  22 , a first side  24 , a second side  26 , a closed end  28  and an open end  30 . A mounting boss  32  extends outwardly from side  24  for pivotal attachment to the spring arm  14 . A similar boss  33  extends outwardly from side  26  of housing member  18  for pivotal attachment to the spring arm  14 . 
     A pair of cable lugs  34  and  36  extend inwardly through openings formed in end  28  of housing member  18  which are electrically connected to a bus bar  42  by bolts  38  and  40  respectively. The rectangular, electrically conductive bus bar  42  is positioned in housing member  18  as will be described hereinafter. Screws  44  extend downwardly through holes  45  formed in bus bar  42  as will be described hereinafter. Bus bar  42  is provided with a plurality of circular recesses  46  formed therein each of which receive one end of a spring  48 . 
     Assembly  16  also includes a housing member  50  having an end portion  52  which is received by housing member  18  in a snap-fit manner. The lower end of end portion  52  engages bus bar  42  to maintain bus bar  42  in the position illustrated in  FIG. 4 . Housing member  50  has a plurality of collector shoe segment compartments  54  formed therein as seen in  FIG. 3 . An electrically conductive collector shoe segment  56  is movably positioned in each of the compartments  54 . In  FIG. 6 , the segment  56  has beveled portions  56 A and  56 B at each of its ends and a beveled outer end  56 C. The segment  56  includes a flat portion  58  as seen in  FIG. 6 . A flexible electrical lead  60  extends between each of the segments  56  and the bus bar  46  as seen in  FIG. 5 . Each of the leads  60  has a ring connector  61  secured thereto. A rivet or screw  44  extends through a pair of ring connectors  61  to secure the same to the bus bar  46 . The outer end of each of the springs  48  is received by a recess  62  in the inner end of the respective segment  56 . Each of the segments  56  has laterally extending shoulders  64  and  66  to limit the outer movement of the segments with respect to the housing member  50 , as seen in  FIG. 5 . 
     As stated,  FIG. 6  illustrates one form of the collector shoe segment  56 . In  FIG. 7 , a modified form of the collector shoe segment  56 ′ is shown. Collector shoe segment  56 ′ has beveled ends and a beveled outer end as seen in  FIG. 7 . Collector shoe segment  56 ′ also has a flat surface  58 ′ as seen in  FIG. 7 . 
     The drawings illustrate that the shoe assembly  16  has six collector shoe segments aligned in a parallel fashion for engagement with the conductor rail  14  but that number could be increased or decreased if necessary. When the spring arm  14  yieldably urges collector shoe assembly  16  into contact with the conductor rail  12 , the springs  48  individually urge the associated collector shoe segment  56  into contact with the conductor rail with the flat surfaces  58  thereof being in slidable electrical engagement with the conductor rail. 
     The segmented collector shoe assembly of this invention is comprised of multiple, independently sprung, collector shoes as described hereinabove. The segmented collector shoes are connected together to a bus bar in the top of the shoe housing as described above. The segmented collector shoe assembly of this invention offers a solution in a package that is the same size as the prior art shoe and mounts directly to the standard arm  14 . The independently sprung collector segments provide at least three points of contact each. This better distributes the electrical load over the full length of the collector shoe resulting in a lower current density at each point of contact. The lower current density results in less heat developing at each point. In preliminary testing, the segmented shoe of this invention was able to carry double the current at the same temperature as a standard shoe of the prior art. 
     The multiple segmented collectors of this invention provide more contact surfaces to the conductor rail creating less variability in the contact resistance along the rail. Therefore, there is less voltage fluctuation resulting in a more dependable signal. By distributing the current through additional contact points as provided in the invention herein, results in less heat produced at each point. This keeps each point well below the melting point of the shoe material and prevents damage of the shoes and conductor rail. 
     Although the invention has been described in language that is specific to certain structures and methodological steps, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structures and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed invention. Since many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.