Abstract:
A step unit comprises: a step member which is provided on the vehicle body side so as to be adjacent to a slide door of the vehicle and has a flat plate section on which an occupant&#39;s foot is placed; and a drive device which is affixed to the step member and drives the slide door to open and close the slide door. The step member is molded using a resin material and has a accommodation portion which is provided with a bottom formed below the upper surface of the flat plate section. The drive device is affixed while at least a part thereof is accommodated within the accommodation portion.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a step unit, which includes a step member adjacent to a vehicle sliding door, and a drive device for the vehicle sliding door. 
     BACKGROUND OF THE INVENTION 
     Conventionally, a step unit is provided on a vehicle main body at a position that is adjacent to a vehicle sliding door. One type of typical step unit includes a step member and a drive device (motor unit), which is fixed to the step member and operates to open and close a vehicle sliding door. For example, refer to Patent Document 1. 
     In such a step unit, the step member is typically formed through sheet-metal processing and has a flat plate portion, on which occupants put their feet. The drive device is mounted at a position of the flat plate portion where the drive device is least obstructive to occupants. For example, the drive device is mounted at a position on the flat plate portion that is at the rearmost end. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-132141 
     SUMMARY OF THE INVENTION 
     However, in the above described step unit, since the drive device is fixed onto the flat plate portion, on which an occupant put a foot, the drive device undesirably protrude upward from the upper surface of the flat plate portion by a significant amount. This, for example, hampers a low-floor design of the passenger compartment. The drive device may be fixed to the lower surface of the step member, or the side that faces the ground surface. However, there is a limitation to the space below the step member, and the configuration has other drawbacks. For example, the waterproof design for the drive device (and its control circuit) would be complicated. 
     Accordingly, it is an objective of the present invention to provide a step unit that easily reduces upward protrusion of a drive device by a great degree. 
     According to the present invention, a step unit that includes a step member and a drive device is provided. The step member is provided on a vehicle main body to be adjacent to a vehicle sliding door, and has a flat plate portion for allowing an occupant to put his/her foot thereon. The drive device is fixed to the step member, and is for operating the vehicle sliding door to open and close. The step member is molded of a resin material and has an accommodation portion, which has a bottom that is formed at a position lower than an upper surface of the flat plate portion. The drive device is fixed such that at least a part thereof is accommodated in the accommodation portion. 
     This configuration reduces upward protrusion of the drive device from the upper surface of the flat plate portion. As a result, a low-floor design of the passenger compartment is possible. Further, unlike conventional step members, the step member is not formed through sheet-metal processing, but is molded of a plastic material. This allows the step member to have wide variety of shapes. Accordingly, it is possible to form the bottom of the accommodation portion at a position significantly lower than the upper surface of the flat plate portion. Therefore, it is possible to reduce upward protrusion of the drive device from the upper surface of the flat plate portion by a great degree. 
     A peripheral wall may be molded integrally with the step member to encompass the accommodation portion. The peripheral wall extends to a position upward of the upper surface of the flat plate portion. 
     This configuration restricts liquid from entering the accommodation portion, for example, from the upper surface of the flat plate portion. The drive device is therefore prevented from being wet. Particularly, it is difficult to form the peripheral wall about the accommodation portion through sheet-metal processing. However, since the step member is molded of a plastic material, the peripheral wall can be easily molded integrally with the step member. 
     A loop belt may be supported by a pulley provided on the lower surface of the step member and be arranged in an opening-closing direction of the vehicle sliding door. In this case, the drive device is used for rotating the belt. Also, a shaft support portion may be molded integrally with the step member, and the pulley may be detachably and rotationally supported by the shaft support portion. 
     This configuration eliminates the need for additional components such as a bracket for attaching the pulley and facilitates the attachment of the pulley. Particularly, it is difficult to form the shaft support portion, to which a pulley can be detachably attached and rotationally supported, through sheet-metal processing. However, since the step member is molded of a plastic material, the shaft support portion can be easily molded integrally with the step member. 
     The shaft support portion may be a non-annular shaft support portion, which has an opening on a side opposite to the direction of force that is perpendicular to the axis and applied to the pulley by the belt in a taut state. Further, the pulley may be attached to the non-annular shaft support portion by being inserted through the opening. 
     According to this configuration, the pulley is attached to the non-annular shaft support portion by being inserted through the opening. This allows the pulley to be easily installed and prevented from falling off by a force in a direction perpendicular to the axis applied by the belt in a taut state. 
     A loop belt may be provided on the lower surface of the step member and arranged in an opening-closing direction of the vehicle sliding door, and the drive device may be used for rotating the belt. Further, a regulation portion for regulating the position of the belt may be molded integrally with the lower surface of the step member to extend from the lower surface, and a metal sheet member may be fixed to a surface of the regulation portion on which the belt slides. 
     This configuration easily reduces wear of the regulation portion, which is molded of a plastic material. Also, wear of the belt can be reduced. Further, it is possible to reduce the generation of noise during operation. 
     The metal sheet member may be press fitted to the step member. 
     This configuration eliminates the necessity for fasteners such as screws for fixing. Particularly, it is difficult to form the metal sheet receiving portion, to which the metal sheet member is press fitted, through sheet-metal processing. However, since the step member is molded of a plastic material, the metal sheet receiving portion can be easily molded integrally with the step member. 
     The metal sheet member may have a folded back portion for preventing the belt from falling off downward. 
     This configuration prevents the belt from falling off downward without increasing the number of components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view from above illustrating a step unit according to one embodiment; 
         FIG. 2  is a perspective view from below illustrating the step unit according to the embodiment; 
         FIG. 3  is a partial plan view illustrating the step unit according to the embodiment; 
         FIG. 4A  is a cross-sectional view of the step member taken along line  4 A- 4 A in  FIG. 3 ; 
         FIG. 4B  is a cross-sectional view of the step member taken along line  4 B- 4 B in  FIG. 3 ; 
         FIG. 5  is a partial exploded perspective view from below illustrating the step unit according to the embodiment; 
         FIG. 6  is a partial bottom view illustrating the step unit according to the embodiment; 
         FIG. 7  is an explanatory exploded perspective view from below illustrating the support extensions and the rail plate member of the embodiment; 
         FIG. 8  is a partial bottom view illustrating the step unit according to the embodiment; 
         FIG. 9A  is a cross-sectional view taken along line  9 A- 9 A in  FIG. 8 ; 
         FIG. 9B  is an enlarged view illustrating the part surrounded by the line formed by a long dash alternating with a short dash in  FIG. 9A ; 
         FIG. 10  is a partial perspective view from below illustrating the step unit according to a modification; 
         FIG. 11  is a partial bottom view showing a step unit the modification; and 
         FIG. 12  is a perspective view showing a metal sheet member according to the modification. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment according to the present invention will now be described with reference to  FIGS. 1 to 9 . 
     A vehicle has a step unit  1  shown in  FIG. 1 , which is located adjacent to a vehicle sliding door (not shown). In  FIGS. 1 and 2 , “outside” refers to the outside of the passenger compartment in the direction of the vehicle width, and “inside” refers to the direction toward the center of the passenger compartment in the direction of the vehicle width. 
     The step unit  1  is a type that includes a drive device (motor unit)  2  for opening and closing the vehicle sliding door. The step unit  1  is mainly constituted of the drive device  2  and a substantially plate-like step member (step)  3 . The step unit  1  is fixed to the main body (not shown) of the vehicle. The entire upper surface of the step unit  1  is covered with a scuff plate, which is a thin plate-like decorative member (not shown). The upper surface of the drive device  2  (the lower surface of the thin plate-like scuff plate) is covered with a rigid plate or a cover (not shown). 
     The step member  3  is molded of a plastic material. The step member  3  is located in the passenger compartment at a position adjacent to the vehicle sliding door in the closed state, and includes a flat plate portion  4 , on which an occupant places a foot when getting in or out of the vehicle, and an accommodation portion  5  (see  FIGS. 4A and 4B ). The accommodation portion  5  is formed continuous to the flat plate portion  4  and is located on a side of the flat plate portion  4  in the opening direction of the sliding door, or rearward of the flat plate portion  4 . The step member  3  is fixed with a part of the drive device  2  accommodated in the accommodation portion  5 . 
     Specifically, when the accommodation portion  5  is installed in the vehicle, a bottom  5   a  of the accommodation portion  5  is located at a lower position than an upper surface  4   a  of the flat plate portion  4  as shown in  FIGS. 4A and 4B . The height (depth) of the bottom  5   a  of the accommodation portion  5  is determined based on the shape of the drive device  2 . As shown in  FIGS. 1 and 3 , the drive device  2  includes a motor  2   a , which is a drive source, an output portion  2   b , which has a gear attached to the motor  2   a  and an electromagnetic clutch, a control circuit portion  2   c , which is installed in the output portion  2   b . The accommodation portion  5  includes a motor accommodating section  5   b , an output portion accommodating section  5   c , and a circuit accommodating section  5   d  as shown in  FIGS. 4A and 4B . The drive device  2  is fixed by screws such that it partly contacts the bottom  5   a  of the accommodation portion  5 , that is, a part of the drive device  2  is located lower than the upper surface  4   a  of the flat plate portion  4 . One third or more of the entire thickness of the drive device  2  in the vertical direction is located below the upper surface  4   a  of the flat plate portion  4 . In the present embodiment, substantially half the entire thickness is located below the upper surface  4   a . In the present embodiment, a peripheral wall  6  is molded integrally with the step member  3  to encompass the accommodation portion  5 . More specifically, the peripheral wall  6  substantially entirely surrounds the accommodation portion  5  as shown in  FIGS. 1 ,  3 ,  4 A and  4 B. The peripheral wall  6  extends to a position above the upper surface  4   a  of the flat plate portion  4 . 
     As shown in  FIG. 2 , pulleys  11 ,  12  are located on the lower surface of the step member  3 . A loop belt  13  is supported by the pulleys  11 ,  12  and extends in the opening-closing direction of the vehicle sliding door. The drive device  2  rotates the belt  13 . That is, as shown in  FIG. 4A , an output shaft  2   d  of the output portion  2   b  of the drive device  2  extends through a through hole  5   e  formed in the bottom  5   a  of the accommodation portion  5  and protrudes from the lower surface of the step member  3 . The output shaft  2   d  transmits power to the belt  13  via a power transmitting portion  14  (see  FIG. 2 ), which is provided on the lower surface of the step member  3 , thereby rotating the belt  13 . In the present embodiment, the opening-closing direction of the vehicle sliding door corresponds to the front-rear direction of the vehicle. However, the path of the sliding door is curved inward toward the center of the passenger compartment at a front portion in accordance with the closed position of the vehicle sliding door. The position of the belt  13  is regulated by the pulleys  11 ,  12 , which are located at ends in the vehicle front-rear direction, and a regulation portion  15 , which is located between the pulleys  11  and  12  and extends from the lower surface of the step member  3 . The regulation portion  15  is molded integrally with the lower surface of the step member  3 . 
     Non-annular shaft support portions  16 , which serve as a shaft support portion, are molded integrally with the step member  3 . The pulley  11 , which is located at the front end, is rotationally supported by the non-annular shaft support portions  16  as shown in  FIGS. 5 and 6 . The non-annular shaft support portions  16  are formed to support the pulley  11  in a detachable and rotational manner. Specifically, the non-annular shaft support portions  16  are formed in a pair each having an opening  16   a  on the side opposite to the direction of the force that is perpendicular to the axis and applied to the pulley  11  by the belt  13  in a taut state. In other words, the openings  16   a  are located on the front side. The pulley  11  has a shaft  11   a , which is fitted to the openings  16   a , so that the pulley  11  is rotationally supported by the non-annular shaft support portions  16 . The width of the openings  16   a  is slightly smaller than the diameter of the shaft  11   a  of the pulley  11  to form a holding structure, in which, regardless of the force applied by the belt  13 , the pulley  11  does not come off when receiving a small force. The pulley  12 , which is located at the rear end, is rotationally supported by the cover of the power transmitting portion  14  as shown in  FIG. 2 . 
     A pair of lower rails  21 ,  22  is molded integrally with the lower surface of the step member  3  as shown in  FIG. 2 . The lower rails  21 ,  22  extend in the opening-closing direction of the vehicle sliding door (substantially, the front-rear direction of the vehicle). The lower rails  21 ,  22  are connected to each other at both ends in the opening-closing direction (that is, substantially the front-rear direction of the vehicle). As shown in  FIGS. 7 and 8 , a cutout portion  21   a  is formed in a part of the lower rail  21 . A rail plate member  31  is arranged at the cutout portion  21   a  to make the lower rail  21  continuous in the opening-closing direction of the vehicle sliding door. Rollers  32  (see  FIG. 8 ) are provided between the lower rails  21 ,  22  (including the rail plate member  31 ). The rollers  32  are coupled to the vehicle sliding door, for example, via brackets (not shown). Thus, the rollers  32  and the vehicle sliding door are guided in the opening-closing direction by the lower rails  21 ,  22 . The rollers  32  are coupled to the belt  13  via brackets (not shown), so that, as the belt  13  rotates, the rollers  32  are moved in the opening closing direction while being guided by the lower rails  21 ,  22 . 
     Specifically, as shown in  FIGS. 7 to 9A , the step member  3  has an insertion slit  23  extending in the vertical direction at a position that corresponds to the cutout portion  21   a . Also, the step member  3  has support extensions  21   b . The support extensions  21   b  extend from the ends of the cutout portion  21   a  of the lower rail  21  to support the rail plate member  31  against the load applied to the rail plate member  31  by the rollers  32  (see  FIG. 8 ). As shown in  FIG. 8 , the pair of support extensions  21   b  extend from the ends of the cutout portion  21   a  of the lower rail  21  in the direction in which load is applied (upward as viewed in  FIG. 8 , and toward the outside with respect to the vehicle width direction), to approach each other without being connected to each other, so that there is a space therebetween. The support extensions  21   b  are thicker than the lower rail  21  in the direction in which the load is applied (the up-side direction as viewed in  FIG. 8 ). 
     On the other hand, the rail plate member  31  is formed by processing a metal plate, and installed by being inserted through the insertion slit  23  from above the step member  3  as shown in  FIG. 7 . As shown in  FIGS. 1 and 7 , the rail plate member  31  has an angled portion  31   a  at the upper edge (the upper edge in a state after being installed). The angled portion  31   a  extends in a direction perpendicular to the vertical direction, or into the passenger compartment in the present embodiment. The rail plate member  31  is inserted into the insertion slit  23  such that the lower side of the angled portion  31   a  contacts the upper surface of the step member  3 . In the present embodiment, the rail plate member  31  is fixed through press-fitting as shown in  FIG. 9B . Specifically, the rail plate member  31  has a pair of press-fit portions  31   b , which protrude from the sides of the rail plate member  31  that face the ends of the cutout portion  21   a  to be press fitted to the ends of the cutout portion  21   a . When being inserted through the insertion slit  23  from above the step member  3 , the rail plate member  31  is press fitted when the press-fit portions  31   b  are pressed against the ends of the cutout portion  21   a  of the lower rail  21 . At this time, the sides of the cutout portion  21   a  of the lower rail  21  are shaven or elastically deformed by the press-fit portions  31   b . However, as long as the rail plate member  31  can be press fitted, the structure may be changed. 
     In the above described configuration, the rail plate member  31  can be removed to insert rollers  32  into the space between the lower rails  21 ,  22  through the cutout portion  21   a  or remove the rollers  32  from the space between the lower rails  21 ,  22 . When the drive device  2  is operated, the belt  13  is rotated. Accordingly, the rollers  32  are moved while being guided by the lower rails  21 ,  22 , and the vehicle sliding door is operated to open or close. The output shaft  2   d  of the drive device  2  or the housing of the drive device  2  has an O-ring, which is not shown, so that water is completely or almost completely prevented from entering the interior of the drive device  2  or the bottom  5   a  of the accommodation portion  5  through the through hole  5   e  formed in the bottom  5   a  of the accommodation portion  5 . 
     The present embodiment operates and has advantages as described below. 
     (1) The drive device  2  is fixed such that a part thereof is accommodated in the accommodation portion  5 , which has the bottom  5   a , and the bottom  5   a  is formed at a position lower than the upper surface  4   a  of the flat plate portion  4 , on which an occupant put a foot. This structure reduces the amount of protrusion of the drive device  2  from the upper surface  4   a  of the flat plate portion  4 . As a result, the low-floor design of the passenger compartment is possible. Further, unlike conventional step member, the step member  3  is not formed through sheet-metal processing, but molded of a plastic material. This allows the step member  3  to have wide variety of shapes. Accordingly, it is possible to form the bottom  5   a  of the accommodation portion  5  at a position significantly lower than the upper surface  4   a  of the flat plate portion  4 . Therefore, it is possible to reduce upward protrusion of the drive device  2  from the upper surface  4   a  of the flat plate portion  4  by a great degree. 
     (2) The peripheral wall  6  is molded integrally with the step member  3  to encompass the accommodation portion  5  of the step member  3 . The peripheral wall  6  extends to a position above the upper surface  4   a  of the flat plate portion  4 . This reduces entry of liquid to the interior of the accommodation portion  5  from the upper surface  4   a  of the flat plate portion  4 . The drive device  2  is therefore prevented from being wet. Particularly, it is difficult to form the peripheral wall  6  about the accommodation portion  5  through sheet-metal processing. However, since the step member  3  is molded of a plastic material, the peripheral wall  6  can be easily molded integrally with the step member  3 . 
     (3) The step member  3  includes the integrally molded non-annular shaft support portions  16 , which is a support shaft portion for detachably and rotationally support the pulley  11 . This eliminates the necessity for additional components such as brackets. Also, the pulley  11  can be easily assembled with the non-annular shaft support portions  16 . Particularly, it is difficult to form the shaft support portion, to which the pulley  11  can be detachably attached and rotationally supported, through sheet-metal processing. 
     However, since the step member  3  is molded of a plastic material, the shaft support portion can be easily molded integrally with the step member  3 . 
     (4) The shaft support portion includes the non-annular shaft support portions  16 , which have openings  16   a  on the side opposite to the direction of the force that is perpendicular to the axis and applied to the pulley  11  by the belt  13  in a taut state. The pulley  11  is inserted to the openings  16   a  to be attached to the non-annular shaft support portions  16 . This allows the pulley  11  to be easily installed and prevented from falling off by a force in a direction perpendicular to the axis applied by the belt  13  in a taut state. It is difficult to form the pair of non-annular shaft support portions  16  described in the present embodiment through sheet-metal processing. However, since the step member  3  is molded of a plastic material, the non-annular shaft support portion  16  can be easily molded integrally with the step member  3 . 
     The above-described embodiment may be modified as follows. 
     In the above illustrated embodiment, the regulation portion  15  is molded integrally on the lower surface of the step member  3  to regulate the position of the belt  13 , and the position of the belt  13  is regulated only by the regulation portion  15 . However, as shown in  FIGS. 10 to 12 , a metal sheet member  42  may be fixed to a surface of a regulation portion  41  on which the belt  13  sides. 
     Specifically, the regulation portion  41  for regulating the position of the belt  13  is molded integrally with the lower surface of the step member  3 . The regulation portion  41  has a metal sheet receiving portion  41   a  at a position on which the belt  13  is likely to slide as shown in  FIGS. 10 and 11 . The metal sheet receiving portion  41   a  of this modification is configured to have an arcuate bulge  41   b  protruding toward the belt  13  as viewed from below (in the state installed in the vehicle, see  FIG. 11 ) and locking grooves  41   c , which are provided on the sides of the bulge  41   b . On the other hand, as shown in  FIG. 12 , the metal sheet member  42  is formed to be curved and has an elastic piece  42   a  at in a lower portion (lower end when installed in the vehicle, the upper end as viewed in  FIG. 12 ). The elastic piece  42   a  is formed by cutting and raising from the back of the metal sheet member  42  (concave side). The side edges of the metal sheet member  42  are fitted in the locking grooves  41   c , and the elastic piece  42   a  is elastically deformed and pressed against the bulge  41   b , so that the metal sheet member  42  is fixed to the regulation portion  41  of the step member  3 . The elastic piece  42   a  is arranged at a position lower than the position of the belt  13 , the vertical position of which is determined by the brims of the pulleys  11 ,  12  (refer to  FIG. 10 ). Therefore, the belt  13  slides on the smooth front surface (bulging curved surface) of the metal sheet member  42 , on which the elastic piece  42   a  is not formed. 
     The metal sheet member  42  of this modification has a folded back portion  42   b  at the lower end (lower end in a state installed in the vehicle, upper end as viewed in  FIG. 12 ) as shown in  FIGS. 10 to 12 . The folded back portion  42   b  prevents the belt  13  from falling off downward. 
     Since the metal sheet member  42  is fixed to the surface of the regulation portion  41  that slides on the belt  13 , wear of the regulation portion  41  molded of plastic material is easily suppressed. Also, wear of the belt  13  can be reduced. Further, it is possible to reduce the generation of noise during operation. 
     Since the metal sheet member  42  is press-fitted in the step member  3 , no additional fasteners such as screws are needed. Particularly, it is difficult to form the metal sheet receiving portion  41   a , to which the metal sheet member  42  is press fitted, through sheet-metal processing. However, since the step member  3  is molded of a plastic material, the metal sheet receiving portion  41   a  can be easily molded integrally with the step member  3 . 
     Since the metal sheet member  42  has a folded back portion  42   b  for preventing the belt  13  from falling off downward, it is possible to prevent the belt  13  from falling off downward without increasing the number of components. 
     The metal sheet member  42  may be press fitted to the step member  3  using other structure. Also, the metal sheet member  42  may be fixed to the step member  3  using fastening members such as screws. The folded back portion  42   b  may be omitted. 
     The peripheral wall  6  may be omitted. 
     As a shaft support portion for rotationally supporting a shaft, the non-annular shaft support portions  16  may be replaced by other separate members such as brackets that rotationally support the pulley  11 . The shaft support portion may have any configuration other than that of the non-annular shaft support portions  16 , which have the openings  16   a , as long as the shaft support portion is molded integrally with the step member  3  and can detachably and rotationally support the pulley  11 . That is, a shaft support portion may be employed that does not have a function for preventing the pulley  11  from being caused to fall off by a force that is perpendicular to the direction of the axis and applied by the belt  13  in a taut state. 
     The step member  3  does not need to have the accommodation portion  5 , in which the bottom  5   a , which is at a position lower than the upper surface  4   a  of the flat plate portion  4 . Even in this case, the advantages (3) and (4) can be achieved.