Vehicle undercarriage

Abstract

To arrange a slide rail and a step device under a locker in a reasonable manner as much as possible, while securing support property of the step plate.SOLUTION: A step device 40 having a slide rail (lower slide rail 19) for supporting a slide door 20 so as to be slidable and movable in an opening / closing direction, and a step plate 41 as a tread is arranged on a vehicle lower side of a locker 30, and the slide rail (19) is arranged immediately just under the step plate 41 so as to abut thereon.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage in which a slide rail for a sliding door and a step device having a step plate serving as a tread are provided under a rocker that forms the lower edge of a door opening. [Background technology]

[0002] Related technologies are described in Patent Documents 1 and 2. The vehicle disclosed in Patent Document 1 has a door opening provided in the vehicle body that can be opened and closed in the longitudinal direction of the vehicle by a sliding door. A cylindrical side sill, which corresponds to the locker of the present application, is provided at the lower edge of the door opening and extends in the longitudinal direction of the vehicle. A slide rail that supports the sliding door so that it can slide is provided below the side sill and extends in the longitudinal direction of the vehicle. A bracket that protrudes inward in the vehicle width direction is provided at the lower end of the sliding door, and a roller journaled by the bracket is slidably fitted into the slide rail. This allows the sliding door to slide in the longitudinal direction of the vehicle by sliding the roller along the slide rail.

[0003] In addition, in the vehicle of Patent Document 2, a cylindrical rocker is provided at the lower edge of the door opening so as to extend in the fore-and-aft direction of the vehicle. A step serving as the tread surface of a step device is disposed below this rocker. The step is configured so as to be movable between a stored position disposed below the rocker and an extended position protruding outward in the vehicle width direction from the rocker. When a step is disposed below the rocker as in Patent Document 2, the slide rail described above is generally housed in the rocker. That is, a portion of the shape (cross-sectional shape) of the rocker is formed into a concave shape that opens outward in the vehicle width direction, and the slide rail is housed in this concave portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-76482 [Patent Document 2] Japanese Patent Application Publication No. 2019-127145 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described vehicle, there is a demand for arranging the slide rail and step device under the rocker. That is, arranging the slide rail and step device under the rocker increases the freedom of rocker shape selection, making it easier to ensure the rocker's rigidity and also makes it easier to avoid interference between the slide rail and other components (such as the battery inside the vehicle). Furthermore, in the above-described configuration, there is a demand for ensuring the supportability of the step plate by, for example, supporting the step plate from the underside of the vehicle. For example, if the step plate is moved by a link, the rigidity of the link can be increased, but this increases the mass of the link and increases costs. Another option is to provide a separate component to support the step plate. However, due to the limited space under the rocker, it is difficult to arrange multiple components separately, and attempting to do so may result in unintended design constraints on each component. The present invention was devised in light of the above-described issues, and the problem it aims to solve is to arrange the slide rail and step device under the rocker as effortlessly as possible while ensuring the supportability of the step plate. [Means for solving the problem]

[0006] As a means for solving the above problems, the vehicle undercarriage of the first invention includes a sliding door that opens and closes a door opening in a vehicle body, and a cylindrical locker that forms the lower edge of the door opening. A slide rail that supports the sliding door so that it can slide in the opening and closing direction, and a step device with a step plate that serves as a tread, are arranged on the vehicle underside of the locker. In this type of configuration, it is desirable to be able to arrange the slide rail and step device under the rocker as effortlessly as possible while ensuring support for the step plate. Therefore, the slide rail of the present invention is arranged directly below the step plate so that it can abut against it. In the present invention, the slide rail is configured to abut against the step plate and support it. Therefore, with the above configuration, there is no need to arrange a separate member to support the step plate, and the slide rail and step device can be arranged under the rocker as effortlessly as possible.

[0007] The vehicle understructure of the second invention is the vehicle understructure of the first invention, wherein, when a direction perpendicular to the opening / closing direction is defined as the inward / outward direction of the vehicle based on a plan view in the vehicle's up-down direction, the step plate is configured to be displaced, while in contact with the slide rail, between a stored position where the locker is located below the vehicle and a deployed position where the locker is located further outward than the stored position. In this invention, the slide rail and the step plate are always in contact, and the slide rail can support the step plate in both the stored position and the deployed position.

[0008] The undercarriage of a vehicle according to the third invention is the undercarriage of a vehicle according to the first or second invention, When the direction perpendicular to the opening and closing direction is defined as the inside-outside direction of the vehicle based on a plan view in the vertical direction of the vehicle, The step plate is connected to the rocker by a link that is pivotally connected to the step plate. Located under the locker Storage location and positioned further outward from the storage position. configured to be displaced between deployed positions; TeRo The rocker is provided with a base end support portion that supports the base end portion of the link on the rocker side, and the slide rail is located further outward from the base end support portion. In this invention, the step plate in the deployed position to which a load is applied from above the vehicle can be more stably supported by the slide rail that is located further outward from the base end support portion.

[0009] The vehicle understructure of the fourth invention is the vehicle understructure of the first or second invention, in which the slide rails are arranged further outward than the rockers when the direction perpendicular to the opening / closing direction is defined as the vehicle inward / outward direction based on a plan view in the vehicle's up-down direction. In this invention, the step plate to which a load is applied from above the vehicle can be more stably supported by the slide rails arranged further outward than the rockers.

[0010] The vehicle understructure of the fifth invention is the vehicle understructure of the fourth invention, in which the upper side of the slide rail is covered by a fixed step plate fixed to the rocker at the vehicle upper position of the step plate. In this invention, the fixed step plate functions to minimize exposure of the slide rail to the outside and also suppresses movement of the step plate toward the upper side of the vehicle when a load is applied. [Effects of the Invention]

[0011] According to the first aspect of the present invention, the slide rail and step device can be arranged under the rocker as effortlessly as possible while ensuring support for the step plate. According to the second aspect, the support for the step plate can be more reliably ensured. According to the third aspect, the support for the step plate supported by the link can be even more reliably ensured. According to the fourth aspect, the support for the step plate can be even more reliably ensured. And according to the fifth aspect, the slide rail and step device can be arranged under the rocker in a more attractive manner while more appropriately ensuring support for the step plate. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. [Figure 2] FIG. 2 is an enlarged perspective view of the lower part of the vehicle showing the step device. [Figure 3] 3 is a cross-sectional view of the vehicle taken along line III-III in FIG. 2. [Figure 4]FIG. 2 is a plan view of the vehicle when the sliding door is fully opened, as viewed from below the vehicle. [Figure 5] FIG. 2 is a cross-sectional view of the vehicle when the sliding door is fully closed. [Figure 6] FIG. 2 is a plan view of the vehicle when the sliding door is fully closed, as viewed from below the vehicle. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 4. [Figure 8] FIG. 2 is an enlarged perspective view of the vehicle showing the guide roller unit. [Figure 9] 10 is a side view of a vehicle showing the movement of a bracket portion of a sliding door. FIG. [Figure 10] FIG. 2 is a plan view of the vehicle showing the movement locus of the sliding door and the rotation locus of the four-bar linkage mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 10. In each figure, arrows indicating the front-rear direction, left-right direction (vehicle width direction), and up-down direction (vehicle height direction) of the vehicle are appropriately shown. Furthermore, based on Figs. 4 and 6 (plan view in the vehicle up-down direction), the front-rear direction corresponds to the opening and closing direction of the sliding door, and the vehicle width direction perpendicular to the opening and closing direction corresponds to the vehicle inward-outward direction. In each figure, the left side on the outer side in the vehicle width direction corresponds to the vehicle outer side, and the left side on the inner side in the vehicle width direction corresponds to the vehicle inner side. Note that Fig. 1 shows only the left side of the vehicle, and illustrates the sliding door in an open state.

[0014] [Vehicle Overview] Before describing the vehicle's undercarriage, an overview of a vehicle 2 shown in Figure 1 will be given. A vehicle body 10 of this vehicle 2 is formed with a front door opening 11 corresponding to the front seats and a rear door opening 12 corresponding to the rear seats. The front door opening 11 is configured to be openable and closable by a front door 15 that can rotate about a door hinge (not shown). The rear door opening 12 is configured to be openable and closable by a sliding door 20 that slides in the fore-and-aft direction of the vehicle. As shown in Figure 2, a rocker 30, which is a cylindrical frame, is provided at the lower edge of the rear door opening 12 so as to extend in the fore-and-aft direction of the vehicle, and a fixed step plate 33 is provided on this rocker 30 so as to protrude outward in the vehicle width direction.

[0015] 1 is provided with a plurality of slide rails 17, 18, 19 that support a sliding door 20 so that it can slide in the fore-and-aft direction of the vehicle (opening and closing direction). For example, in the vehicle 2 shown in FIG. 1, an upper slide rail 17 is provided on the upper side of the rear door opening 12. Also, a center slide rail 18 is provided at the center position in the height direction on the rear side of the rear door opening 12. And a lower slide rail 19 is provided on the lower side of the rear door opening 12, i.e., on the lower side of the rocker 30 and the fixed step plate 33.

[0016] 1 and 2, the sliding door 20 is provided with guide roller units 25 and the like at its upper end position, lower end position, and intermediate position (for convenience, in each drawing, only the position where the lowest guide roller unit is provided is denoted by the corresponding reference numeral 25). The corresponding guide roller units 25 and the like move (slide, etc.) along the slide rails 17 to 19, so that the sliding door 20 can slide along these slide rails 17 to 19. The sliding door 20 moves generally in the longitudinal direction of the vehicle between the fully open position and the fully closed position, but moves diagonally inward in the vehicle width direction near the fully closed position (see the movement locus Do of the sliding door shown in FIG. 10).

[0017] 2 and 3, a step device 40 having a step plate 41 serving as a tread surface is disposed below the locker 30. Furthermore, an internal member 3 such as a battery installed under the floor of the vehicle 2 is disposed on the inside (right side) of the locker 30 in the vehicle width direction as shown in FIG. 3. The locker 30 is disposed at a height position higher than the height position H of the internal member 3, which makes it easy to secure a sufficient distance from the ground in the height direction (ground clearance).

[0018] [Vehicle undercarriage] In the vehicle undercarriage of this embodiment, as shown in FIG. 3 , the lower slide rail 19 and the step device 40 are disposed below the rocker 30 (under the rocker). This increases the flexibility in selecting the shape of the rocker 30, making it easier to ensure rigidity. Furthermore, by utilizing the space below the sliding door 20, the lower slide rail 19 is positioned on the outer side (left side) in the vehicle width direction, thereby avoiding interference between the lower slide rail 19 and the internal member 3. In this type of configuration, it is desirable to be able to dispose the lower slide rail 19 and the step device 40 below the rocker without any design constraints while ensuring the supportability of the step plate 41. Therefore, in this embodiment, the configuration described below is used to dispose the lower slide rail 19 and the step device 40 below the rocker as comfortably as possible while ensuring the supportability of the step plate 41. Below, the vehicle undercarriage will be described in detail in the order of the rocker 30, the step device 40, the lower slide rail 19, and the sliding door 20.

[0019] [locker] First, the rocker 30 shown in FIG. 3 is cylindrically formed from an outer rocker 31 and an inner rocker 32, and is provided along the lower edge of the rear door opening 12. The outer rocker 31 has an upper plate surface 311, a lower plate surface 312, and a left plate surface 313, and is formed with a generally horizontal U-shaped cross section, with the inside (right side) of the outer rocker 31 open in the vehicle width direction. The upper plate surface 311 and the lower plate surface 312 of the outer rocker 31 extend inward in the vehicle width direction, and the lower plate surface 312 protrudes inward relatively significantly. An upper flange portion 31a bent upward toward the vehicle is formed at the upper end of the upper plate surface 311, and a lower flange portion 31b bent downward toward the vehicle is formed at the lower end of the lower plate surface 312. The upper plate surface 311 and the lower plate surface 312 are continuous with the left plate surface 313, which extends in the vehicle up-down direction, on the outer side (left side) of the outer rocker 31 in the vehicle width direction. The inner rocker 32 has an upper plate surface 321, a lower plate surface 322, and a right side plate surface 323, and is formed with a generally horizontal U-shaped cross section, with the outer side in the vehicle width direction being open. The upper plate surface 321 of the inner rocker 32 protrudes relatively far outward. Upper and lower flanges 32a, 32b bent in the vehicle vertical direction are also formed at the upper and lower end positions of the inner rocker 32.

[0020] The rocker 30 shown in FIG. 3 is formed with a generally rectangular cylindrical cross section by joining the outer rocker 31 and the inner rocker 32 together in the vehicle width direction. Specifically, the upper flanges 31a, 32a and the lower flanges 31b, 32b are joined by welding or the like. The rocker 30 is thus formed with a generally rectangular cylindrical cross section that eliminates the recesses for slide rails, resulting in a cross section that contributes to ensuring rigidity. Furthermore, the rocker 30 has a cross section with excellent rigidity, which allows for a compact design by reducing its vertical dimensions. This allows the rocker 30 to be installed at a height higher than the height position H of the internal member 3, thereby contributing to ensuring ground clearance. The upper flanges 31a, 32a of the rocker 30 are located near the outer (left) end of the vehicle width direction, and the lower flanges 31b, 32b are located near the inner (right) end of the vehicle width direction. In addition, the left side plate surface 313 of the outer rocker 31 forms the outer surface of the rocker 30 in the vehicle width direction.

[0021] [Fixed step board] 2 and 3, a fixed step plate 33, which serves as a tread surface for an occupant, is fixed to the outer (left) surface in the vehicle width direction of the rocker 30. As shown in FIG. 2, this fixed step plate 33 is formed so as to extend in the vehicle front-rear direction along the rocker 30. As shown in FIG. 3, the fixed step plate 33 is formed in a generally L-shape in cross section and is fixed to the left plate surface 313 of the outer rocker 31 by a vertical wall portion 34 extending in the vehicle up-down direction. The fixed step plate 33 also has a horizontal wall portion 35 that protrudes outward in the vehicle width direction at the lower end of the vertical wall portion 34, and this horizontal wall portion 35 serves as a tread surface for an occupant. The fixed step plate 33 is reinforced by a reinforcing member 36 that is generally L-shaped in cross section and integrated with the back side of the fixed step plate 33. In other words, the vertical wall portion 34 and the rear portion of the horizontal wall portion 35 are reinforced by the reinforcing member 36, thereby increasing the rigidity of the fixed step plate 33 against forces applied from the vehicle up-down direction.

[0022] [Step device (step board)] Next, the step device 40 shown in FIGS. 2 and 3 has a step plate 41 and a four-bar link mechanism 43 (described in detail later) that supports the step plate 41. In the step device 40, the step plate 41 and the four-bar link mechanism 43 are disposed under the rocker. The fixed step plate 33 of the rocker 30 is disposed above the step plate 41 on the vehicle. The step plate 41 is a member that serves as a tread surface for an occupant and is supported generally horizontally under the rocker by the four-bar link mechanism 43. As shown in FIG. 4, the step plate 41 is formed as a long plate in the front-to-rear direction, with its front side narrower than its rear side. As will be described later, the step plate 41 is configured to be displaceable between a deployed position on the outer side (left side) of the vehicle width direction shown in FIGS. 3 and 4 and a stored position under the rocker shown in FIGS. 5 and 6.

[0023] The step plate 41 shown in FIG. 3 has a tip 410 on the outer side (left side) in the vehicle width direction bent into a substantially L-shape, extending substantially perpendicularly to the vehicle lower side and then extending inward in the vehicle width direction (right side). A fixed plate portion 411 is fixed and integrated with the tip 410 so as to cover the outer side in the vehicle width direction. A rail portion 42 is fixed and supported at the lower end of the tip 410 of the step plate 41 so as to protrude inward in the vehicle width direction. The rail portion 42 has an inverted U-shaped cross section so that the rolling rollers 28 of the guide roller unit 25, which will be described later, can be fitted into the rail portion 42 from below the vehicle. The rail portion 42 forms the outer end of the step plate 41, i.e., a convex end that protrudes inward in the vehicle width direction. As will be described later, fitting the rolling rollers 28 into the rail portion 42 enables the step plate 41 provided with the rail portion 42 to be linked to the opening and closing operation of the sliding door 20.

[0024] As shown in FIG. 4 , the rail portion 42 extends in the vehicle front-rear direction along the edge of the step plate 41 on the outer side (left side) in the vehicle width direction. This rail portion 42 is composed of a front straight portion 420, a bent portion 421, and a rear straight portion 422. The front straight portion 420 is formed to extend linearly in the vehicle front-rear direction at the front position of the step plate 41. The bent portion 421 is bent at a predetermined angle from the rear end of the front straight portion 420 outward in the vehicle width direction, and the rear straight portion 422 is formed to extend linearly in the vehicle front-rear direction from the rear end of the bent portion 421. Referring to FIGS. 4 and 10 , the front straight portion 420 is formed to intersect with a trajectory of the sliding door 20 when it starts moving in the opening direction, i.e., a movement trajectory Do near the fully closed position, as will be described later. The bent portion 421 and the rear straight portion 422 are formed to follow the movement trajectory Do when the sliding door 20 moves in the opening direction.

[0025] [Four-bar link mechanism (link)] 3 and 4, the four-bar link mechanism 43 is a mechanism that supports the step plate 41 so that it can move between a retracted position and an extended position. As shown in Fig. 4, the four-bar link mechanism 43 has a front support link 43f and a rear support link 43b that are formed to be equal in length. The front support link 43f and the rear support link 43b are axially connected to the step plate 41 and the rocker 30, respectively, as will be described later. Here, the connection modes of the support links 43f, 43b are generally the same, so the following detailed description will be given mainly of the front support link 43f as an example.

[0026] Referring to FIG. 4, a base end portion of the front support link 43f on the inner side (right side) in the vehicle width direction is axially connected to a base end bracket 37 fixed to the inner side of the rocker 30 in the vehicle width direction. Here, the base end bracket 37 is formed to extend in the vehicle front-rear direction, and a front support portion 37sf is provided at the front portion of the base end bracket 37. As shown in FIG. 7, the front support portion 37sf has a hat-shaped cross section and is provided to protrude downward from the lower surface (lower plate surface 312) of the rocker 30 toward the bottom of the vehicle. The base end portion of the front support link 43f is placed on the front support portion 37sf from above and is axially connected to the front support portion 37sf by the front rotation center shaft 43c in a horizontally rotatable manner. Furthermore, a tip end portion of the front support link 43f on the outer side (left side) in the vehicle width direction shown in FIG. 4 is axially connected to a tip bracket 38 fixed to the step plate 41. The tip bracket 38 is formed to extend in the front-to-rear direction of the vehicle, and is formed so that its front and rear portions are one step lower than the step plate 41. The tip portion of the front support link 43f is axially connected to the front part of the tip bracket 38 by the front tip connecting shaft 43x in a horizontally rotatable state.

[0027] [Proximal support part] Furthermore, the base end of the front support link 43f shown in Figures 3 and 4 is supported by a support plate 44 provided on the inner side (right side) of the rocker 30 in the vehicle width direction. As shown in Figure 4, this support plate 44 extends in the front-to-rear direction of the vehicle so as to follow the rotational path of the front support link 43f. As shown in Figure 3, the support plate 44 is fixed to the underside of the rocker 30 so as to be positioned directly above the base end of the front support link 43f. This makes it possible to support the base end of the front support link 43f, which moves between the retracted position and the deployed position, by sandwiching it between the front support portion 37sf (base end bracket 37) and the support plate 44. As a result, a base end support portion 45 that supports the base end of the front support link 43f is formed in the rocker 30 at the position where the support plate 44 is disposed.

[0028] 4 is axially connected to the rear support portion 37sb of the base end bracket 37 by a rear rotation center shaft 43e. The tip end of the rear support link 43b is axially connected to the rear portion of the tip bracket 38 by a rear tip connecting shaft 43y. The base end of the rear support link 43b is also supported by another support plate portion 44a, and another base end support portion 45a that supports the base end of the rear support link 43b is formed at the position of this another support plate portion 44a.

[0029] [Four-bar link mechanism function] Here, with reference to FIG. 10 , the manner in which the step plate 41 is displaced by the four-bar linkage mechanism 43 will be described (interlocking with the sliding door will be described later). First, the distance between the front and rear tip connecting shafts 43x, 43y connected to the step plate 41 side is set to a value equal to the distance between the rotation center shafts 43c, 43e connected to the rocker 30 side. In addition, the front support link 43f and the rear support link 43b are formed with equal dimensions. Therefore, when the front support link 43f and the rear support link 43b of the four-bar linkage mechanism 43 rotate horizontally, the step plate 41 moves along the arc trajectory S while being held parallel to the rocker 30 in a plan view. Then, the tip ends of both support links 43f, 43b rotate horizontally around the rotation center shafts 43c, 43e to a left rotation limit position, rotated left by a predetermined angle relative to the rocker 30 (see the solid line portion in FIG. 10 ). As a result of the tip portions of both support links 43f, 43b rotating counterclockwise about the rotation central axes 43c, 43e in this manner, the step plate 41 protrudes outward in the vehicle width direction (to the left) from under the rocker and is held in the deployed position (see FIGS. 3 and 4). Also, the tip portions of both support links 43f, 43b rotate horizontally to a right-rotation limit position rotated clockwise by a predetermined angle relative to the rocker 30 about the rotation central axes 43c, 43e (see the two-dot dashed line in FIG. 10). As a result of the tip portions of both support links 43f, 43b rotating clockwise about the rotation central axes 43c, 43e in this manner, the step plate 41 is held in a stored position located under the rocker (see FIGS. 5 and 6).

[0030] [Slide rail] Next, the lower slide rail 19 shown in Fig. 4 is disposed below the rocker via connecting members 51, 52, and 53, which will be described later. The lower slide rail 19 is formed so as to follow the movement path of the sliding door 20 (see movement path Do in Fig. 10), and has a bent portion 190 and a straight portion 191. The bent portion 190 is formed at the front portion of the lower slide rail 19, and is gradually bent inward in the vehicle width direction (to the right) as it approaches the front of the vehicle. The straight portion 191 is continuous with the rear end of the bent portion 190, and extends linearly so as to follow the opening and closing direction of the sliding door 20 (the vehicle longitudinal direction).

[0031] In addition, in the cross-sectional view shown in FIG. 3 , the lower slide rail 19 is formed in a hollow column shape with an open outer side (left side) in the vehicle width direction. This lower slide rail 19 is formed from an upper wall portion 192, a lower wall portion 193, and a vertical wall portion 194 connecting the upper and lower wall portions. The upper wall portion 192 has an inverted U-shaped cross section with an open lower side, so that a guide roller 26 of a guide roller unit 25 (described later) can be slidably fitted therein. A band-shaped support portion 196 that is always in contact with the step plate 41 is integrally formed on the upper surface of the upper wall portion 192, so that the step plate 41 can slide smoothly on this support portion 196. In addition, the lower wall portion 193 is a flat-plate-shaped portion located on the vehicle lower side of the upper wall portion 192, and is capable of slidably supporting a load roller 27 of the guide roller unit 25 (described later).

[0032] [Containment section] As shown in Fig. 3, the upper wall portion 192 and the lower wall portion 193 are continuous with a vertical wall portion 194 extending in the vehicle up-down direction on their inner side (right side) in the vehicle width direction. As a result, the lower slide rail 19 is formed in a hollow column shape with an open outer side (left side) in the vehicle width direction, and an opening portion 195 communicating with the outside on the outer side in the vehicle width direction is formed at the same height as the rail portion 42 of the step plate 41 described above. As will be described later, when the step plate 41 moves inward in the vehicle width direction, the rail portion 42 provided on this step plate 41 is guided into the lower slide rail 19 through the opening portion 195 (see Fig. 5). When the step plate 41 moves outward in the vehicle width direction, the rail portion 42 is pulled out from the lower slide rail 19 to the outer side in the vehicle width direction through the opening portion 195 (see Fig. 3). In this way, the lower slide rail 19 shown in FIG. 3 has the above-described configuration, and forms the accommodation portion 100 that accommodates the rail portion 42 (the end portion on the outer side of the vehicle) of the step plate 41 in a state where it can be pulled out in the vehicle width direction.

[0033] 4 and 6, the lower slide rail 19 is configured to accommodate a part of the step plate 41 in the vehicle longitudinal direction, i.e., the wider rear side of the step plate 41. The rear side of the step plate 41 is provided with a bent portion 421 and a rear straight portion 422 of the rail portion 42 shown in FIG. 4. The bent portion 421 and the rear straight portion 422 are formed so as to follow the movement locus when the sliding door 20 moves in the opening direction, as described above (see movement locus Do in FIG. 10). As a result, the bent portion 421 and the rear straight portion 422 of the rail portion 42 are formed in the same shape as the portion from the rear of the bent portion 190 to the straight portion 191 of the lower slide rail 19. Therefore, the lower slide rail 19 (accommodating portion 100) can accommodate the bent portion 421 and the rear straight portion 422 of the rail portion 42 by moving the rail portion 42 inward (right side) in the vehicle width direction, as shown in FIG. The front straight portion 420 of the rail portion 42 extends linearly so as to intersect with the movement trajectory of the sliding door 20. Therefore, when the step plate 41 is in the retracted position, the front straight portion 420 of the rail portion 42 is disposed on the outer side of the lower slide rail 19 (bent portion 190) in the vehicle width direction.

[0034] [Connecting member] 4, connecting members 51, 52, and 53 are disposed at the front, middle, and rear end positions of the lower slide rail 19 in the vehicle longitudinal direction. That is, a first connecting member 51 is disposed at the bent portion 190 (front position) of the lower slide rail 19. A second connecting member 52 and a third connecting member 53 are disposed at the front and rear ends (middle and rear end positions) of the straight portion 191 of the lower slide rail 19. Since the connecting members 51 to 53 have substantially the same basic configuration, the second connecting member 52 will be taken as an example for detailed description below.

[0035] The second connecting member 52 shown in Figures 3 and 4 is formed in a plate shape extending in the vehicle width direction and is disposed between the straight portion 191 of the lower slide rail 19 and the front support portion 37sf of the rocker 30. This second connecting member 52 is bent in a crank shape in the cross-sectional view shown in Figure 3, and its base end portion 520 on the inner side (right side) in the vehicle width direction is one step higher. This base end portion 520 is disposed near the flange portions 31b, 32b at the lower end position of the rocker 30 described above. The base end portion 520 (portion on the vehicle inner side) is fixed to the lower plate surface 312 of the rocker 30 in a state where it is fastened to the front support portion 37sf shown in Figure 7.

[0036] 3 is formed so that a main body portion 521, which is one step lower than a base end portion 520, extends outward in the vehicle width direction (to the left). Furthermore, in the second connecting member 52, a tip end portion 522 of the main body portion 521 is bent at a substantially right angle toward the underside of the vehicle, and this bent tip end portion 522 constitutes a portion of the second connecting member 52 that is closer to the vehicle outside than the base end portion 520 (the portion fixed to the locker). The main body portion 521 extends to a position further outward in the vehicle width direction than the support plate portion 44 (base end support portion 45), and the tip end portion 522 is disposed further outward in the vehicle width direction than the locker 30. In this way, the second connecting member 52 extends from the flange portions 31b, 32b at the lower end position, i.e., the end position on the inner side of the locker 30 in the vehicle width direction, across the locker 30 to the outer side in the vehicle width direction.

[0037] 3, the vertical wall portion 194 of the lower slide rail 19 is fixed to a tip end portion 522 on the outer (left) side in the vehicle width direction of the second connecting member 52. As a result, the lower slide rail 19 is disposed below the rocker via the second connecting member 52 and is disposed at a position outer in the vehicle width direction than the support plate portion 44 (base end support portion 45) described above. Furthermore, by being fixed to the tip end portion 522 of the second connecting member 52, the lower slide rail 19 protrudes outward in the vehicle width direction of the rocker 30 and is disposed below the fixed step plate 33. As a result, the upper side of the lower slide rail 19 can be covered by the fixed step plate 33, minimizing exposure of the lower slide rail 19 to the outside. Furthermore, the lower slide rail 19 is disposed at a height position approximately the same as or higher than the height position H of the internal member 3 described above, which contributes to ensuring ground clearance.

[0038] [Reinforcement] 3 and 4, the second connecting member 52 is reinforced at appropriate locations with reinforcing portions (50A, 50B). Specifically, front and rear reinforcing bead portions 523 extending in the vehicle width direction are provided at a lower main body portion 521 of the second connecting member 52 at appropriate intervals in the vehicle longitudinal direction (for convenience, the front and rear reinforcing bead portions are denoted by the same reference numeral 523 in FIG. 4). The front and rear reinforcing bead portions 523 correspond to the first reinforcing portion 50A and are formed by deforming the second connecting member 52 in a direction that locally raises the second connecting member 52. The front and rear reinforcing bead portions 523 are provided so as to traverse the main body portion 521 in the vehicle width direction, thereby increasing the rigidity of the second connecting member 52 against loads applied from the outside in the vehicle width direction. The second connecting member 52 is reinforced by a hollow columnar lower slide rail 19 fixed to the tip portion 522 (the end portion on the outside in the vehicle width direction) of the second connecting member 52. The lower slide rail 19 is disposed so as to protrude downward from the vehicle body portion 521 of the second connecting member 52. The lower slide rail 19 is disposed so as to longitudinally cross the second connecting member 52 in the front-to-rear direction of the vehicle, so that the second connecting member 52 can appropriately bear a load applied from the outside in the vehicle width direction. Note that the first connecting member 51 and the third connecting member 53 are also provided with reinforcing portions 50A, 50B, similar to the second connecting member 52 (in FIG. 4, for convenience, the first reinforcing portions of each connecting member are denoted by the common reference numeral 50A).

[0039] [Sliding door] Next, the sliding door 20 shown in FIGS. 1 to 3 is formed by joining a door outer panel and a door inner panel (not shown) at their peripheral edges. A bracket portion 23 for a guide roller unit is fixed to the lower end of the door inner panel of the sliding door 20. As shown in FIG. 3, this bracket portion 23 has a generally L-shaped cross section and is fixed to the lower end of the sliding door 20 by a vertical wall-like fixing portion 23a extending in the vertical direction of the vehicle. The bracket portion 23 also has a horizontal wall-like installation portion 23b extending substantially horizontally from the lower end of the fixing portion 23a toward the inside of the vehicle. As shown in FIG. 4, the installation portion 23b is formed so as to extend toward the front side of the vehicle and toward the inside (right side) in the vehicle width direction in a state where a guide roller unit 25 (described later) is disposed therein.

[0040] First, the guide roller unit 25 shown in FIG. 4 has front and rear guide rollers 26 and a load roller 27 for the slide rail (for convenience, the front and rear guide rollers are given the same reference numeral 26 in FIG. 4). Referring to FIG. 8, an upper support portion 261 for the guide rollers and a lower support portion 271 for the load roller are provided at the distal end of the installation portion 23b of the bracket portion 23 on the inner side (right side) in the vehicle width direction. The upper support portion 261 is formed in a substantially U-shape in plan view, and a vertically oriented first shaft member 260 is provided at the bifurcated free end side. A horizontally oriented guide roller 26 corresponding to each first shaft member 260 is rotatably supported, and each guide roller 26 is slidably fitted in the upper wall portion 192 of the lower slide rail 19, as shown in FIGS. 3 and 8.

[0041] 3 and 8, a vertically oriented second shaft 270 is provided at the distal end of the mounting portion 23b of the bracket portion 23, and a lower support portion 271 having a substantially horizontal U-shaped cross section is rotatably supported by the vertically oriented second shaft 270. The lower support portion 271 supports a horizontally oriented third shaft 272 that protrudes toward the inside (right side) in the vehicle width direction, and a vertically oriented load roller 27 is rotatably supported by the third shaft 272. The load roller 27 is slidably supported by the lower wall portion 193 of the lower slide rail 19. The load roller 27, which is supported by the lower support portion 271, can be turned so as to follow the lower slide rail 19 by rotating the lower support portion 271 about the vertically oriented second shaft 270.

[0042] 3 and 4 has a rolling roller 28 for the step plate. That is, a vertically oriented fourth shaft member 280 is provided near the outer side (left side) in the vehicle width direction of the installation portion 23b of the bracket portion 23 shown in FIG. 3, and the horizontally oriented rolling roller 28 is rotatably supported by this fourth shaft member 280. The rolling roller 28 is slidably fitted into the rail portion 42 of the step plate 41, whereby the sliding door 20 provided with the rolling roller 28 is interlockedly connected to the step plate 41. The rail portion 42 into which the rolling roller 28 can be fitted constitutes a mechanism that interlocks the sliding door 20 and the step plate 41.

[0043] [Step device in storage position] 5 and 6, when the sliding door 20 is in the fully closed position, the step device 40 in the storage position is disposed on the inner side (right side) of the closed sliding door 20 in the vehicle width direction. At this time, the front support link 43f and the rear support link 43b of the four-bar linkage mechanism 43 are horizontally rotated to the right rotation limit position around the rotation center shafts 43c, 43e as shown in Fig. 6. As a result, the step plate 41 is disposed below the vehicle of the rocker 30 and the fixed step plate 33 and is held in the storage position as shown in Fig. 5.

[0044] 5 and 6, the lower slide rail 19 is disposed under the rocker together with the step device 40. In this type of configuration, as described above, it is desirable that the lower slide rail 19 and the step device 40 can be disposed under the rocker without any design restrictions while ensuring the support of the step plate 41. Therefore, referring to FIG. 5, the vehicle understructure is configured so that the lower slide rail 19 can be supported by abutting against the step plate 41. Therefore, in the above configuration, it is not necessary to separately provide a member for supporting the step plate 41, and the lower slide rail 19 and the step device 40 can be disposed under the rocker as effortlessly as possible. Therefore, the support provided by the lower slide rail 19 will be specifically described below in the order of the stored position and the deployed position.

[0045] [Step support in storage position] First, the step plate 41 in the storage position shown in Fig. 5 is disposed below the vehicle of the locker 30 and the fixed step plate 33 as described above. The lower slide rail 19 is disposed below the vehicle of the fixed step plate 33 while being supported by the second connecting member 52 and the like. The lower slide rail 19 is disposed directly below the step plate 41, so that the lower slide rail 19 (support portion 196) can come into contact with and support the step plate 41. The support portion 196 is configured to always come into contact with the step plate 41 while the step plate 41 is being displaced from the storage position to the deployed position, as will be described later.

[0046] [Step board position displacement] Next, the behavior of the step device 40 when it is moved from the stored position to the deployed position will be described. With reference to Fig. 9, when the sliding door 20 starts to move in the opening direction from its fully closed position, the bracket portion 23 provided on the sliding door 20 moves toward the rear of the vehicle. At this time, as shown in Fig. 10, the guide rollers 26 and the load roller 27 of the guide roller unit 25 slide relative to the slide rail 19, so that the sliding door 20 slides toward the rear of the vehicle along the slide rail 19 (see the movement locus Do of the sliding door shown in Fig. 10).

[0047] 10 , when the sliding door 20 starts to move, the guide rollers 26 and the load roller 27 of the guide roller unit 25 described above move toward the rear of the vehicle along the bent portion 190 of the lower slide rail 19 (see the rollers indicated by the two-dot dashed line in FIG. 10 ). The rolling rollers 28 of the guide roller unit 25 also move toward the rear of the vehicle along the front straight portion 420 of the rail portion 42 of the step plate 41 (see the portion indicated by the two-dot dashed line). The front straight portion 420 of the rail portion 42 intersects with the movement locus Do when the sliding door 20 starts to move in the opening direction from the fully closed position, as described above. Therefore, while the rolling rollers 28 move along the front straight portion 420 (see arrow A1 in FIG. 10 ), a moving force of the sliding door 20 outward in the vehicle width direction is applied to the rail portion 42 via the rolling rollers 28, and the step plate 41 is pressed outward (leftward) in the vehicle width direction. As a result, the front support link 43f and the rear support link 43b of the four-bar linkage 43 rotate counterclockwise around the corresponding rotation central shafts 43c and 43e, and the step plate 41 moves horizontally outward in the vehicle width direction. Then, by the time the rolling rollers 28 move to the rear end of the front straight section 420, the step plate 41 is subjected to the above-mentioned moving force and is displaced from the stored position to the deployed position.

[0048] 6 and 10, when the sliding door 20 starts to move, the front straight portion 420 of the rail portion 42 is not stored in the front portion of the bent portion 190 as described above. Therefore, the guide roller 26 and the load roller 27 can move to their rear end positions along the bent portion 190 of the lower slide rail 19. In addition, as shown by the solid line in Fig. 10, when the step plate 41 is displaced to the extended position, the rail portion 42 provided on this step plate 41 is pulled outward (to the left) in the vehicle width direction from the lower slide rail 19. When the rail portion 42 is pulled out from the lower slide rail 19 in this way, the guide roller 26 and the load roller 27 can enter the rear side of the bent portion 190.

[0049] 10, the sliding door 20 further slides to the fully open position. At this time, the guide roller 26 and the load roller 27 move along the rear portion of the bent portion 190 and the straight portion 191 of the lower slide rail 19. The rolling roller 28 enters the bent portion 421 from the front straight portion 420 of the rail portion 42, and then moves along the bent portion 421 and the rear straight portion 422 (see arrow A2 in FIG. 10). The bent portion 421 and the rear straight portion 422 of the rail portion 42 are formed to follow the movement locus Do of the sliding door 20, as described above. Therefore, while the rolling roller 28 rolls between the bent portion 421 and the rear straight portion 422, the moving force of the sliding door 20 is not applied to the rail portion 42 of the step plate 41. Therefore, the step plate 41 is held in the retracted position until the sliding door 20 moves to the fully open position. When the sliding door 20 is closed from the fully open position to the fully closed position, the step plate 41 is returned to the storage position by the reverse operation of the above-described operation.

[0050] [Step support in deployed position] As the step plate 41 moves from the stored position to the deployed position, it is positioned further outward (leftward) in the vehicle width direction than the stored position, as shown in FIG. 3 . The support portion 196 of the lower slide rail 19 is always in contact with the step plate 41, thereby supporting the step plate 41 in the deployed position. As described above, the lower slide rail 19 is positioned further outward in the vehicle width direction than the rocker 30, and therefore supports a position closer to the left edge of the step plate 41 on the outer side in the vehicle width direction than the rocker-side support plate portion 44 (base end support portion 45). This allows the lower slide rail 19 to more stably support the step plate 41 in the deployed position when a load Fu (such as a stepping load) is applied from above the vehicle. When the load Fu is applied to the step plate 41, the inner side in the vehicle width direction (right side) tends to move upward in the vehicle, but this upward movement of the step plate 41 can be suppressed by the fixed step plate 33, which has increased rigidity.

[0051] Furthermore, with the above-described configuration, the distance between the left edge of the step plate 41 (load point, the portion located directly above the rail portion 42 in the same figure) and the lower slide rail 19 (support point) shown in FIG. 3 can be shortened as much as possible, so there is no need to excessively increase the rigidity of the step plate 41. Also, since the step plate 41 does not need to be supported by the front support link 43f and the rear support link 43b shown in FIG. 4 when getting on and off, there is no need to excessively increase the rigidity of these links 43f, 43b. Therefore, according to the vehicle undercarriage structure, the function of the lower slide rail 19 enables the step device 40 to be simplified in configuration and lighter in weight.

[0052] [Vehicle Undercarriage Advantages] In this way, the vehicle undercarriage of this embodiment is configured so that the lower slide rail 19 can be supported by contacting the step plate 41. Therefore, with the above-described configuration, it is not necessary to provide a separate member for supporting the step plate 41, and the lower slide rail 19 and the step device 40 can be disposed under the rocker as effortlessly as possible. Therefore, according to this embodiment, the lower slide rail 19 and the step device 40 can be disposed under the rocker as effortlessly as possible while ensuring the supportability of the step plate 41.

[0053] Furthermore, in this embodiment, the lower slide rail 19 and the step plate 41 are always in contact with each other, so that the lower slide rail 19 can support the step plate 41 in both the stored position and the deployed position. Furthermore, in this embodiment, the step plate 41 in the deployed position when a load is applied from above the vehicle can be more stably supported by the lower slide rail 19, which is located further outward from the base end support portion 45. Particularly in this embodiment, the step plate 41 in the deployed position when a load is applied from above the vehicle can be more stably supported by the lower slide rail 19, which is located further outward from the rocker 30. Furthermore, in this embodiment, the fixed step plate 33 functions to minimize exposure of the lower slide rail 19 to the outside and to suppress upward movement of the step plate 41 in the deployed position when a load is applied.

[0054] [Another advantage of the vehicle's undercarriage (1)] Furthermore, in the vehicle undercarriage structure, an increase in the storage space for the lower slide rail 19 and the step device 40 can be minimized. That is, the lower slide rail 19 shown in FIG. 5 is disposed below the fixed step plate 33 in a vehicle-mounted manner, with its position relative to the locker 30 remaining unchanged as described above. The lower slide rail 19 forms a hollow columnar storage portion 100, and an opening 195 is formed on its outer side in the vehicle width direction (left side). Next, the step plate 41 is provided with a rail portion 42 at its outer end in the vehicle width direction so as to protrude toward the inner side in the vehicle width direction (right side). The rail portion 42 and the lower slide rail 19 (opening 195) are disposed at approximately the same height. According to the above-described configuration, when the step plate 41 is displaced to the storage position and the rail portion 42 is disposed below the fixed step plate 33, the rail portion 42 is accommodated in the lower slide rail 19 through the opening 195. This allows the rail portion 42 of the step plate 41 and the lower slide rail 19 to be arranged so as to overlap in the vehicle width direction, making it easier to ensure storage space in the vehicle width direction compared to when each component is arranged separately. In particular, with the above-mentioned configuration, the rail portion 42 (convex end portion) protruding inward in the vehicle width direction and the lower slide rail 19 (concave storage portion 100) having a substantially horizontal U-shaped cross section can be fitted together in the vehicle width direction. Furthermore, by accommodating the rail portion 42 within the lower slide rail 19, the rail portion 42 is less likely to protrude from the lower slide rail 19 toward the underside of the vehicle. As a result, the ground clearance of the lower slide rail 19 and the step device 40 is ensured, making it less likely for them to interfere with the ground (road surface).

[0055] [Another advantage of the vehicle's undercarriage (2)] Furthermore, in the vehicle undercarriage structure, the lower slide rail 19 shown in FIG. 5 can be prevented from strongly hitting the inner member 3 in the event of a vehicle collision. That is, in the vehicle undercarriage structure, as shown in FIG. 5, the second connecting member 52 to which the lower slide rail 19 is fixed is provided under the rocker so as to extend in the vehicle width direction. As a result, the second connecting member 52 is disposed between the lower slide rail 19 and the inner member 3 so as to fill the gap between them. By fixing the lower slide rail 19 to the tip portion 522 of the second connecting member 52, the impact load F applied to the slide rail 19 in the event of a vehicle side collision can be borne by the slide rail 19 and the second connecting member 52. In particular, the lower slide rail 19 as the second reinforcing part 50B longitudinally crosses the second connecting member 52 in the vehicle fore-aft direction (opening / closing direction), so that the impact load F applied from the outer side (left side) in the vehicle width direction can be appropriately borne by the lower slide rail 19 and the second connecting member 52. Furthermore, the lower slide rail 19 has the rail portion 42 housed therein to increase its rigidity, thereby preventing the lower slide rail 19 from being excessively deformed when subjected to the impact load F.

[0056] The second connecting member 52 shown in FIG. 5 deforms and absorbs the impact load F applied from the outer side (left side) in the vehicle width direction, thereby suppressing movement of the lower slide rail 19 inward (right side) in the vehicle width direction. As described above, the second connecting member 52 extends outward in the vehicle width direction from the flange portions 31b, 32b at the lower end position and further protrudes outward in the vehicle width direction from the rocker 30. Therefore, the second connecting member 52 can more reliably absorb the impact load F by ensuring its deformation stroke (length in the vehicle width direction). In this way, the lower slide rail 19 to which the impact load F is applied is suppressed from moving inward in the vehicle width direction by the second connecting member 52, so that the lower slide rail 19 is less likely to hit the internal member 3 hard. In particular, the front and rear reinforcing bead portions 523 (first reinforcing portions 50A) of the second connecting member 52 have increased rigidity against the impact load F applied from the outer side in the vehicle width direction, thereby more reliably suppressing movement of the lower slide rail 19. In the vehicle undercarriage, connecting members 51, 52, 53 are disposed at the front, middle, and rear end positions of the lower slide rail 19 shown in Fig. 6. Therefore, the connecting members 51, 52, 53 act to restrict the movement of the lower slide rail 19 inward (to the right) in the vehicle width direction over substantially the entire length of the lower slide rail 19 in the vehicle front-rear direction.

[0057] The vehicle undercarriage of this embodiment is not limited to the above-described embodiment and may take various other forms. In this embodiment, the step plate and slide rail configurations are illustrated, but these configurations are not intended to be limiting. For example, the slide rails may be configured to be able to contact the step plate when a load is applied from above the vehicle. That is, the step plate when a load is applied moves downward toward the vehicle and directly contacts the slide rail. A slight gap may be provided between the step plate and slide rail in a free state. The slide rails may also be configured to support only the step plate in the deployed position. The slide rails may also be arranged so as to be hidden under the rocker. In this case, it is preferable that they be located further outward from the base end support portion of the vehicle. The base end support portion may also be omitted. Furthermore, when the slide rails are located further outward from the rocker, they do not necessarily need to be covered by a fixed step plate. The support portions may be provided continuously or intermittently along the lower slide rail. The material of the support portions is generally resin, but is not limited to this and may be changed as appropriate. In addition, the support portion may be omitted from the lower slide rail, in which case the lower slide rail directly contacts the step plate to support it from below. Note that the opening and closing direction of the slide rail is not necessarily limited to the longitudinal direction of the vehicle.

[0058] In this embodiment, the configuration of the step plate and slide rail is illustrated as an example of the structure relating to the above-mentioned advantage (1), but this configuration is not intended to be limiting. For example, a storage portion can be provided in the step plate, and the vehicle-outside end of the slide rail can be stored in this storage portion. For example, in the slide rail shown in FIG. 3, the lower wall portion supporting the load roller can be omitted. In such a case, the slide rail can be formed with only the upper wall portion for the guide roller. In this case, the upper wall portion constituting the vehicle-outside end of the slide rail can be configured to be stored in a storage portion formed between the lower surface of the step plate and the roller portion. In the above configuration, when the step plate is displaced to the extended position, the upper wall portion of the slide rail is pulled toward the vehicle interior relative to the storage portion. Furthermore, when the step plate is moved electrically, a sensor for detecting an occupant or a sensor for detecting a sliding door (an example of a mechanism) can be disposed at the position of the rail portion. In this case, various sensors constitute the vehicle-outside end (convex end) of the step plate. Note that the vehicle-outside end and the storage portion do not necessarily need to be configured to be fitted from the inside / outside of the vehicle (convex / concave fit). If possible, the end of the step board on the inside of the vehicle may be accommodated in a accommodating portion serving as a slide rail. At least a part of the structure relating to the other advantage (1) can be omitted as needed.

[0059] In this embodiment, the configuration of the slide rail and the connecting member is illustrated as an example of the structure related to the above-mentioned advantage (2). However, this configuration is not intended to be limiting. For example, the slide rail may be supported by multiple connecting members, or by a single connecting member (e.g., by connecting multiple connecting members as shown in FIG. 4). When multiple connecting members are used, the number and arrangement of the connecting members can be changed as needed, and the shape (external shape and cross-sectional shape) of each connecting member can be set. It is also preferable that the connecting member be provided with at least one of a first reinforcing portion and a second reinforcing portion. The first reinforcing portion can be a reinforcing bead portion, a vertical wall-like portion rising from the surface of the main body portion, a flange-like portion formed by bending the outer edge of the main body portion, or the like. The first reinforcing portion can protrude from at least one of the upper and lower sides of the vehicle. The second reinforcing portion can be a portion separate from the slide rail, and this second reinforcing portion can protrude from at least one of the upper and lower sides of the vehicle. The slide rail does not necessarily have to be fixed to the end of the connecting member on the outer side of the vehicle, but may be fixed to a portion on the inner side of the vehicle from that end. The connecting member can also be fixed to an appropriate position on the locker. Examples of internal components include batteries and various components installed in vehicles, such as fuel storage members that store fuel, such as liquid or gaseous fuel. At least a portion of the structure related to the other advantage (2) can be omitted as needed. [Explanation of symbols]

[0060] 2 vehicles 3 Internal components 10 Vehicle body 11 Front door opening 12 Rear door opening 15 Front Door 17 Upper slide rail 18 Center slide rail 19 Lower slide rail (slide rail of the present invention) 190 Bending section 191 Straight section 192 Upper wall 193 Lower wall part 194 Vertical wall section 195 Opening 196 Support part 20 Sliding Door 23 Bracket part 23a Fixed area 23b Installation location 25 Guide roller unit 26 Guide roller 27 Load Roller 28 Rolling roller 30 Lockers 31 Rocker Outerwear 311 (rocker outer) upper surface 312 (Locker outer) bottom plate surface 313 (Outer rocker) left side panel 32 Rocker Inner 321 (Inner rocker) upper surface 322 (Locker inner) bottom plate surface 323 (Inner rocker) right side panel 31a, 32a Upper flange 31b, 32b Lower flange 33 Fixed step board 34 Vertical wall section 35 Side wall part 36 Reinforcement 37 Base end bracket 37sb Rear support part 37sf front support part 38 Tip bracket 40 Step Device 41 Step board 410 Tip 411 Fixed plate part 42 Rail section 420 Front straight section 421 Bend section 422 Posterior straight section 43 Four-bar link mechanism 43f Front support link (link of the present invention) 43b Rear support link (link of the present invention) 43c, 43e Rotation axis 43x, 43y Tip connecting shaft 44 Support plate part 44a Another support plate 45 Proximal support part 45a Alternative base support 51 First connecting member 52 Second connecting member 520 Proximal part 521 Main body part 522 Tip part 523 Reinforced bead 53 Third connecting member 50A First reinforcement 50B Second reinforcement 100 storage unit 260 First shaft material 261 Upper support part 270 Second shaft material 271 Lower support part 272 Third shaft material 280 Fourth shaft member

Claims

1. A vehicle undercarriage having a sliding door that opens and closes a door opening in a vehicle body, and a cylindrical locker that forms a lower edge of the door opening, A slide rail that supports the slide door so that it can slide in the opening and closing direction and a step device that has a step plate that serves as a tread surface are arranged on the vehicle underside of the locker, The slide rail is disposed directly below the step plate so as to be able to abut against the step plate.

2. 2. The vehicle undercarriage structure according to claim 1, wherein, when a direction perpendicular to the opening and closing direction is defined as the inward / outward direction of the vehicle based on a plan view in the vertical direction of the vehicle, the step plate is configured to be displaced between a stored position in which the locker is positioned below the vehicle and an deployed position in which the locker is positioned further outward than the stored position while in contact with the slide rail.

3. When a direction perpendicular to the opening / closing direction is defined as the inward / outward direction of the vehicle based on a plan view in the vertical direction of the vehicle, the step plate is configured to be displaced between a storage position located below the locker and an expanded position located further outward from the vehicle than the storage position by a link that is pivotally connected to the step plate and the rocker, 3. The vehicle undercarriage structure according to claim 1, wherein the rocker is provided with a base end support portion that supports the base end portion of the link on the rocker side, and the slide rail is positioned further outward from the base end support portion.

4. 3. The vehicle undercarriage structure according to claim 1, wherein the slide rail is positioned outside the vehicle relative to the locker when a direction perpendicular to the opening and closing direction is defined as the vehicle interior / exterior direction based on a plan view in the vehicle's vertical direction.

5. 5. The vehicle undercarriage structure according to claim 4, wherein an upper side of the slide rail is covered with a fixed step plate fixed to the rocker at a position above the vehicle of the step plate.

Images