Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/838,800, filed Aug. 18, 2006. 
    
    
     BACKGROUND 
     The invention relates to a step assembly for a motor vehicle. More particularly, the invention relates to a step assembly including a three bar link for moving a step between a stowed position and a retracted position. 
     It is well-known in the art to provide fixed running boards or fixed step assemblies along one side of a motor vehicle to assist individuals in either entering and exiting or accessing a motor vehicle having a high ground clearance. These fixed running boards have, however, certain disadvantages. For example, such fixed running boards are often placed at a height that is not practical for a large number of users. In addition, these fixed running boards are susceptible to dirt and mud accumulation, which can then be easily transferred to a user&#39;s clothing. Moreover, these fixed running boards reduce the ground clearance for the motor vehicle and, as such, can be damaged during off-road motor vehicle operation. 
     Retractable running boards or step assemblies are generally movable between a retracted position, in which a step is tucked underneath an underbody of the motor vehicle, and an extended position, in which the step is spaced apart from the underbody of the motor vehicle to support the user. Retractable running boards commonly incorporate a four-bar link, that is, four distinct members for securing the step to the motor vehicle. The four-bar links occupy, however, a relatively large amount of space along the underbody and such space along the underbody is at a premium. 
     SUMMARY 
     A step assembly includes an upper housing adapted to be fixedly secured to a motor vehicle. A step is movable relative to the upper housing between a stowed position and a deployed position. A single arm is pivotal with respect to the upper housing and pivotal with respect to the step in order to form a three-bar linkage for moving the step between the stowed and deployed positions. 
     According to another aspect of the invention, a step assembly for a motor vehicle includes a pair of spaced apart upper housings adapted to be fixedly secured to the motor vehicle. A drive shaft extends between and is rotatable relative to the pair of spaced apart upper housings. A platform is movable relative to each upper housing between a stowed position and a deployed position. An arm extends between each of the spaced apart upper housings and the platform. Each of the arms includes a first end fixedly secured to the drive shaft and a second end pivotal with respect to the platform for moving the platform between the stowed and deployed positions. 
     According to yet another aspect of the invention, a step assembly for a motor vehicle includes an upper housing adapted to be attached to the motor vehicle. A rotatable shaft is at least partially disposed within the upper housing. An arm has a first end fixedly secured to the rotatable shaft and a second end. A step is fixedly secured to the second end of the arm and movable in response to rotation of the rotatable shaft for movement between a stowed position generally underneath the motor vehicle and a deployed position spaced apart from the motor vehicle in an outboard direction relative thereto. 
     According to still another aspect of the invention, a step assembly for a motor vehicle includes an upper housing fixedly secured to the motor vehicle. The upper housing includes a guide slot. A step is movable relative to the upper housing between a stowed position and a deployed position. An arm is pivotal with respect to the upper housing and pivotal with respect to the step for moving the step between the stowed and deployed positions. An extension member is fixedly secured to the arm. The extension member includes a guide pin received within the guide slot and movable therewithin as the step moves between the stowed and deployed positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a step assembly according to one embodiment of the invention; 
         FIG. 2  is a perspective view of a link of the step assembly; 
         FIG. 3  is a side view of the step assembly including a single arm extending between the link and an upper housing; 
         FIG. 4  is an enlarged side view of the step assembly; 
         FIG. 5  is an exploded, perspective view of a latch assembly for the step assembly including a cover, a latch hub, a pawl mount, and a pawl; 
         FIG. 6  is a perspective view of the latch hub coupled to the pawl mount; 
         FIG. 7  is a perspective view of a step assembly according to a second embodiment of the invention; 
         FIG. 8  is an exploded, fragmentary, perspective view of one end of the step assembly; 
         FIG. 9  is a exploded, perspective view of an arm, drive shaft, and ratchet mechanism of the step assembly; 
         FIG. 10  is a side view of the ratchet mechanism and the arm; 
         FIG. 11A  is a side view of a chain wrapped around a pivot control sprocket; 
         FIG. 11B  is a top view of the chain at a first end of the arm; 
         FIG. 12  is a perspective view of a step assembly according to a third embodiment of the invention; 
         FIG. 13  is a perspective view of a shaft, arm, and step of the step assembly; 
         FIG. 14  is a top view of the shaft, arm, and step of the step assembly; 
         FIG. 15  is a perspective view including a release button operably coupled to a deploy lock pin; 
         FIG. 16  is a side view of a latch hub including a deploy spring; 
         FIG. 17  is a perspective view of the latch hub and a pawl mount; 
         FIG. 18  is a fragmentary, perspective view of the step assembly according to a fourth embodiment of the invention including an arm having an extension member received within a guide slot; 
         FIG. 19  is a side view of a step assembly including the step in the deployed and stowed positions; and 
         FIG. 20  is a side view of a step assembly including an extension member secured to a link and received within a guide slot. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , a step assembly according to one embodiment of the invention is generally shown at  10 . The step assembly  10  includes a step  12  for supporting individuals entering or exiting a motor vehicle. The step  12  includes an outboard end  14 , an opposing inboard end  16 , and a stepping surface  18  extending between the outboard  14  and inboard  16  ends. 
     Referring to  FIGS. 1 through 3 , a link, generally indicated at  20 , is fixedly secured to the step  12  by at least one fastener  22 . As shown in  FIG. 2 , the link  20  includes a main body portion  24  and a pair of spaced apart leg members  26 ,  28  extending out therefrom. The pair of spaced apart leg members  26 ,  28  defines an opening  30  therebetween. Each of the pair of spaced apart leg members  26 ,  28  terminates at a locking end  32 . A cam member  34  is coupled to at least one of the pair of spaced apart leg members  26 ,  28 . The cam member  34  defines a slot  36 . 
     Referring to  FIGS. 3 and 4 , an arm  38  includes a first end  40  pivotally secured to the link  20  about pivot pin  42  and an opposing second end  44  pivotally secured to an upper housing  46  about a pivot pin  48 . The arm  38  provides for pivotal movement of the step  12  between a stowed position, in which a substantial portion of the step  12  is tucked below a body panel of a motor vehicle, and a deployed position (as shown in  FIG. 1 ), in which the step  12  is spaced further apart from the body panel and available to receive individuals entering or exiting the motor vehicle. 
     A lower slot  50  is formed at the first end  40  of the arm  38 . A tilt lock pin  52  is disposed within the lower slot  50 . The tilt lock pin  52  is selectively received within the slot  36  of the cam member  34 . A tilt lock spring  54  is connected to the tilt lock pin  52 . 
     An upper slot  56  is formed at the second end  44  of the arm  38 . A deploy lock pin  58  is received within the upper slot  56 . A deploy spring  60  is connected to the deploy lock pin  58 . The deploy lock pin  58  is selectively positioned within a notch  62  in the upper housing  46 . One end  64  of a release cable or rod  66  is coupled to the deploy lock pin  58  and an opposing end  68  of the release cable  66  is coupled to the link  20 . 
     The upper housing  46  is fixedly secured to the body panel of the motor vehicle to position the step assembly  10  therealong. A latch assembly, generally indicated at  70  in  FIG. 1 , is coupled to the upper housing  46  for retaining the step  12  in the stowed position. Referring to  FIGS. 5 and 6 , the latch assembly  70  includes a latch cover  72  fixedly secured to the upper housing  46  via a plurality of fasteners  74 . A latch hub, generally indicated at  76 , is operatively coupled to the arm  38  at the second end  44  thereof. More specifically, the latch hub  76  and the arm  38  are each fixedly mounted to the pivot pin  48 . Therefore, pivotal movement of the arm  38  results in pivotal movement of the latch hub  76 . The latch hub  76  includes a main body  78  and a latch pin  80  extending out therefrom. In addition, a pair of spaced apart fork members  82 ,  84  extends out from the main body  78 . A deploy spring  86  is secured to the latch hub  76 . 
     A mounting plate  88  is fixedly secured to the upper housing  46  by fasteners  90 . A pawl  92  rotates relative to the mounting plate  88  about a pawl rivet  94 . A washer  96  spaces the pawl  92  away from the mounting plate  88 . 
     In operation, a user desiring to move the step  12  out of the stowed position and into the deployed position provides an initial foot action to the step  12  to pivot the arm  38 . The pivotal movement of the arm  38  pivots the latch hub  76  and disengages the fork members  82 ,  84  thereof from the pawl  92 . The deploy spring  86  biases the step  12  towards the deployed position. The arm  38  will continue to rotate until the distal locking ends  32  of the link  20  engage the arm  38 , which provides a mechanical stop for the step  12 . At the same time, the deploy lock pin  58  is received within the notch  62  in the upper housing  46 . The step  12  is thus retained in the deployed position to assist individuals entering and exiting the motor vehicle. 
     To move the step  12  from the deployed position back to the stowed position, an individual provides an initial foot action to the step  12  in an upward direction A, shown in  FIG. 3 . This initial foot action pulls the distal locking ends  32  of the link  20  downwards. As a result, the release cable  66  pulls the deploy lock pin  58  out of the notch  62  in the upper housing  46 . Additional foot action causes pivotal movement of the arm  38 . At the same time, the latch hub  76  pivots until the latch pin  80  and spaced apart fork members  82 ,  84  are engaged by the pawl  92  so that the latch assembly  70  retains the step  12  in the stowed position. In the stowed position, the tilt lock pin  52  is received within the slot  36  in the cam member  34  in order to prevent the step  12  from tilting out of the stowed position. 
     Referring to  FIGS. 7 through 11 , wherein like primed reference numerals represent similar elements as those set forth above, the step assembly  10 ′ according to a second embodiment of the invention includes a motor  98  operably connected to a drive shaft  100  via a plurality of gears  102 . The drive shaft  100  fixedly supports two arms  38 ′. Rotation of the drive shaft  100  causes each arm  38 ′ to pivot about the pivot pins  42 ,  48  to move the step  12 ′ between the stowed and deployed positions. It is appreciated that in the present embodiment, the step  12 ′ may be a platform step or running board. 
     The step assembly  10 ′ includes a ratchet mechanism, generally shown at  104 , having a pawl  106  interengaging a cam  108  for locking and unlocking the step  12 ′. A pawl pin  110  extends out from the pawl  106 . A pawl toggle spring  112  biases the pawl  106 . The cam  108  is mounted on the drive shaft  100 . Thus, the drive shaft  100 , cam  108 , and arms  38 ′ rotate as a unit. 
     The step assembly  10 ′ also includes a cable  114  and sector  116  for controlling rotation of the step  12 ′ relative to the arms  38 ′. A pin  118  is fixedly secured to each end of the cable  114 . A ball stud  120  is selectively retained by the sector  116 . 
     In an alternative embodiment, a chain  122  may be utilized in place of the cable  114  and sector  116 , as shown in  FIG. 11A , for controlling the rotation of the step  12 ′ relative to the arms  32 ′. The chain  122  wraps around a pivot control sprocket  124 . A pivot control gear  126  is fixedly secured to the pivot pin  42 ′. The pivot control gear  126  is in meshing engagement with a pivot control pinion  128 . The pivot control pinion  128  is fixedly mounted along a pinion shaft  130 . 
     Referring to  FIGS. 12 through 17 , wherein like double-primed reference numerals represent similar elements as those set forth above, the step assembly  10 ″ according to a third embodiment of the invention includes a rotatable shaft  132  having an upper end  134  and an opposing lower end  136 . The lower end  136  of the shaft  132  is fixedly secured to the second end  44 ″ of the arm  38 ″. As a result, rotation of the shaft  132  in one direction will move the step  12 ″ from the stowed position to the deployed position and rotation of the shaft  132  in an opposite direction will move the step  12 ″ from the deployed position to the stowed position. 
     Referring to  FIGS. 14 and 15 , a release button  138 , which extends out from an interior portion of the step  12 ″, is provided to initiate movement of the step  12 ″ from the deployed position to the stowed position. The release button  138  is coupled to one end  140  of an actuator rod  142 . An opposing end  144  of the actuator rod  142  is fixedly secured to a first segment  146  of a bell crank lever, generally indicated at  148 , housed within the step  12 ″. The bell crank lever  148  pivots about a pivot pin  150 . 
     One end  152  of an actuator release rod  154  is fixedly secured to a second segment  156  of the bell crank lever  148 . An opposing end  158  of the actuator release rod  154  is coupled to the deploy lock pin  58 ″ disposed within the upper slot  56 ″ at the second end  44 ″ of the arm  38 ″. 
     The step assembly  10 ″ also includes the latch assembly  70 ″ as set forth in the first embodiment. More specifically, the latch assembly  70 ″ retains the step  12 ″ in the stowed position. The deploy spring  86 ″ biases the step  12 ″ into the deployed position when the latch assembly  70 ″ releases the step  12 ″ from the stowed position. 
     In operation, to move the step  12 ″ from the stowed position to the deployed position, an individual provides an initial foot action to the step  12 ″ in order to disengage the latch hub  76 ″ from the pawl  92 ″, upon which the deploy spring  86 ″ biases the step  12 ″ towards the deployed position. The rotatable shaft  132  rotates and, with it the arm  38 ″, in order to rotate the step  12 ″ about a vertical axis. The deploy lock pin  58 ″ travels through the upper slot  56 ″ until it is received within the notch  62 ″. At this time, the step  12 ″ is in the deployed position. 
     To move the step  12 ″ from the deployed position to the stowed position, the release button  138  is pushed by a foot action, which causes the bell crank lever  148  to pivot about the pivot pin  150  in the direction of arrow A (see  FIG. 14 ). As a result, the actuator release rod  154  is pulled in the direction of arrow B, also shown in  FIG. 14 , and the deploy lock pin  58 ″ is pulled out of the notch  62 ″. The step  12 ″ is now free to move into the stowed position. Continued foot action causes engagement between the latch hub  70 ″ and the pawl  84 ″, the step assembly  12 ″, the latch assembly  64 ″ locks the step  12 ″ in the stowed position. 
     Referring to  FIGS. 18 through 20 , wherein like triple-primed reference numerals represent similar elements as those set forth above, in a fourth embodiment of the invention the arm  38 ′″ of the step assembly  10 ′″ includes an extension member  160 . The extension member  160  may extend out from a middle portion of the arm  38 ′″ between the first  40 ′″ and  44 ′″ ends thereof, as shown in  FIGS. 18 and 19 , or directly from the link  18 ′″, as shown in  FIG. 20 . The extension member  160  includes a guide pin  162  at a distal end  164 . 
     Referring to  FIGS. 18 and 19 , the upper housing  40 ′″ of the step assembly  10 ′″ includes a pair of spaced apart plates  166  receiving the arm  38 ′″ and extension member  160  therebetween. Each of the spaced apart plates  166  includes an aperture  168  for receiving the pivot pin  48 ′″ at the second end  44 ′″ of the arm  38 ′″ to allow for pivotal movement of the arm  38 ′″ relative to the upper housing  46 ′″. Each of the spaced apart plates  166  also includes a guide slot  170  extending between a deploy end  172  and a stow end  174 . The guide slot  170  preferably has an arcuate shape. The guide pin  162  is received within the guide slots  170  to couple the extension member  160  to the upper housing  46 ′″. 
     In operation, when the step  12 ′″ is in the stowed position A, shown in  FIG. 18 , the guide pin  162  is located at the stow end  174  of the guide slot  170 . An initial foot action in the downward direction will cause the arm  38 ′″ to pivot about the pivot pin  42 ′″ and the pivot pin  48 ′″. In response to such pivotal movement, the guide pin  162  begins to move from the stow end  174  of the guide slot  170  to the deploy end  172  thereof. When the guide pin  162  reaches the deploy end  172  of the guide slot  170 , the step  12 ′″ has reached the deployed position B, also shown in  FIG. 18 , and there is no further pivotal movement of the step  12 ′″. The step  12 ′″ is now available for to support a user thereon. 
     In order to move the step  12 ′″ from the deployed position back to the stowed position, an initial foot action in the upward direction is applied to the step  12 ′″. As a result, the arm  38 ′″ pivots about the pivot pin  42 ′″ and the pivot pin  48 ′″. In response to such pivotal movement, the guide pin  162  begins to move from the deploy end  172  of the guide slot  170  to the stow end  174  thereof. When the guide pin  162  reaches the stow end  174  of the guide slot  170 , the step  12 ′″ has reached the stowed position A. In each of the stowed and deployed positions, the guide pin  162  is maintained in place by gravity such that only a certain amount of force is required to move the step  12 ′″ out of either the stowed or deployed positions. 
     Referring to  FIG. 20 , the extension member  160  is fixedly secured to an inboard end  175  of the link  18 ′″. The guide pin  162  at the distal end  164  of the extension member  160  is received within the guide slot  170 . The guide pin  162  moves between the deploy  172  and stow  172  ends of the guide slot  170  as the arm  38 ′″ moves the step  12 ′″ between the deployed and stowed positions. The step assembly  12 ′″ as shown in  FIG. 20  provides good packaging options when in the stowed position and may be either manually operated or automated. 
     In each of the four above-described embodiments of the step assembly  10 ,  10 ′,  10 ″,  10 ′″, a three-bar linkage, i.e., the link  18 , the arm  38 , and the upper housing  46 , is utilized to move the step  12  between the stowed and deployed positions. The three-bar linkage takes up less space along the body panel of the motor vehicle than a traditional four-bar linkage. As a result, the step assembly  10 ,  10 ′,  10 ″,  10 ′″ may be mounted to a wide variety of motor vehicles. 
     The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.

Technology Category: 7