JP2006111235A - Body frame of motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a body frame for a motorcycle formed in a box shape with the bottom left open, capable of enhancing the rigidity of each vertical wall in its plane direction. <P>SOLUTION: The body frame of the motorcycle has a pair of vertical walls arranged confronting each other and with the bottoms opened relative to each other, wherein the bottoms of the left and right vertical walls5s are coupled together by a reinforcing member 27, which is equipped with a front 28 and a rear cross part 29 to connect the vertical walls 5s with each other and a wide coupling part 30 to couple together the cross parts 28 and 29 and having a surface spreading in the axial direction of the cross parts substantially. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a body frame of a motorcycle having a pair of opposing walls that are arranged to face each other and whose ends are open.

The body frame of a motorcycle may be manufactured by die casting from the viewpoint of increasing the rigidity as a strength member while reducing the weight. For example, in Patent Document 1, the body frame is divided into a left half and a right half and each half is formed by casting, and the left and right halves are joined to each other so that the lower end is opened. A box-shaped structure having the above is adopted.
JP 2002-326592 A

  By the way, when a box-shaped body frame having an open lower end is employed, there is a concern that the rigidity of the lower end opening is lowered. Therefore, the above-mentioned conventional publication employs a structure in which the left and right vertical wall portions are connected by a strip-shaped portal bracket.

  However, in the structure in which the left and right vertical wall portions are reinforced with the gate bracket, rigidity in the vehicle width direction can be secured to some extent, but there is a concern that the rigidity in the front-rear direction along the left and right vertical wall surfaces tends to be low. is there. That is, simply connecting the left and right vertical wall portions with the gate bracket cannot prevent the left and right vertical wall portions from shifting in the front-rear direction, and improvement in this respect is demanded.

  The present invention has been made in view of the above circumstances, and provides a vehicle body frame for a motorcycle that can increase the rigidity in the front-rear direction of a vertical wall when a box-shaped vehicle body frame having an open lower end is adopted. It is an object.

  The invention according to claim 1 is a vehicle body frame of a motorcycle having a pair of opposing walls that are arranged so as to face each other and whose ends are open, and a connection wall that connects the opposing walls. The reinforcing members are connected to each other by a reinforcing member that is separate from the opposing wall, and the reinforcing member joins the crossing portions to each other, and substantially crosses the crossing portions. And a wide coupling portion having a surface extending in a direction perpendicular to the connection wall.

  According to a second aspect of the present invention, in the first aspect, the reinforcing member is disposed so as to connect ends of the opposing walls.

  The invention according to claim 3 is the left or right vertical wall according to claim 1 or 2, wherein the pair of opposing walls of the body frame are arranged on one side and the other side in the vehicle width direction and extend in the vehicle front-rear direction and the vertical direction. Between the lower end portions of the left and right vertical walls, and the connection wall is a front vertical wall that integrally connects the front edges of the left and right vertical walls, and the left The front and rear portions of the lower end of the right vertical wall are connected by the front and rear cross portions.

  According to a fourth aspect of the present invention, in the third aspect, the front and rear cross portions are constituted by pipe front and rear cross pipes, and the wide coupling portion is constituted by a flat plate connecting the front and rear cross pipes. It is characterized by being.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a gap is provided between the left and right edge portions of the flat plate and the inner surfaces of the lower end portions of the left and right vertical walls.

  According to a sixth aspect of the present invention, in the third aspect, the vehicle body frame is formed by welding the left and right frame pieces made of casting divided into left and right, and is attached to the inner surfaces of the left and right vertical walls. A mounting boss portion for mounting the cross portion is formed, and the mounting boss portion has a mounting seat surface substantially perpendicular to a die-cutting direction during casting.

  The invention of claim 7 is characterized in that, in claim 4 or 5, a fuel tank is mounted on a flat plate connecting the front and rear cross pipes in the body frame.

  According to the vehicle body frame of the first aspect of the present invention, the reinforcing member that connects the pair of opposing walls includes a plurality of cross portions that connect the opposing walls, and a wide joint that connects the cross portions. Since the wide joint portion has a surface extending in the axial direction of the cross portion and in a direction perpendicular to the connection wall, each cross portion can increase the rigidity in the opposing direction of the opposing wall, The wide coupling portion that couples the cross portions can increase the rigidity in the front-rear direction along the surface of the opposing wall. As a result, it is possible to prevent both the deformation in the facing direction and the displacement in the surface direction of each facing wall when a box-shaped body frame with an open end is adopted.

  Further, a space formed by the opposing walls and the reinforcing member can be used as a storage space.

  In the invention of claim 2, since the reinforcing member is disposed so as to connect the ends of the opposing walls, the capacity of the above-described storage space can be increased.

  In the invention of claim 3, since the front and rear portions of the left and right vertical walls (opposing walls) extending in the vehicle longitudinal direction and the vertical direction are connected by the front and rear cross portions, the left and right vertical surfaces having wide surfaces are connected. The rigidity of the lower end opening of the wall can be improved.

  Further, since the front edges of the left and right vertical walls are connected to each other by a front vertical wall (connection wall) that extends in the vehicle width direction and the vertical direction, the rigidity of the lower end opening of the body frame can be further improved.

  In the invention of claim 4, since the front and rear cross portions are made of pipe front and rear cross pipes, and the wide joint portion is a flat plate extending left and right, the effect of claim 3 is realized with a simple configuration. it can.

  In the invention of claim 5, since the gap is provided between the left and right edge portions of the flat plate and the inner surface of the lower end portion of the left and right vertical walls, the rigidity in the front and rear direction of the left and right vertical walls can be improved. , Weight increase can be suppressed.

  According to the sixth aspect of the present invention, the left and right cast frame pieces divided into the left and right are welded together, and the left and right frame pieces are attached to the inner surfaces of the left and right vertical walls substantially perpendicular to the die cutting direction. Since the mounting boss portion having the seating surface is formed, the mounting boss portion can be easily formed, and a separate part for mounting the front and rear cross portions to the left and right vertical walls can be eliminated.

  In the invention of claim 7, since the fuel tank is mounted on the flat plate in the vehicle body frame, it is possible to support the heavy fuel tank by effectively utilizing the high-rigidity flat plate connected to the front and rear cross portions. It is possible to eliminate the need for support by separate parts.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIGS. 1 to 15 are views for explaining a body frame of a motorcycle according to an embodiment of the present invention. FIG. 1 is a left side view of the motorcycle of the present embodiment, and FIGS. Is a left side view, a perspective view, and a plan view of the body frame, FIG. 5A is a cross-sectional view of the inclined portion of the main frame (a cross-sectional view taken along the line VV in FIG. 2), and FIG. 6 and 7 are cross-sectional views of the main frame suspension (cross-sectional view taken along line VI-VI and VII-VII in FIG. 2), and FIG. 8 is a left side view of the main frame, FIG. Is a cross-sectional view of the footrest support bracket (cross-sectional view taken along the line IX-IX in FIG. 8), FIGS. 10 and 11 are plan views and side views of the footrest support bracket, and FIG. 13 and 14 are plan views and side views of the reinforcing member, and FIG. 15 is the upper support of the fuel tank. It is a cross-sectional view of a part (XIII-XIII line sectional view of FIG. 8). Note that front, rear, left, right, upper, and lower in the present embodiment indicate a positional relationship when viewed in a seated state on the seat.

  In the figure, reference numeral 1 denotes a motorcycle, which has the following schematic structure. A front fork 4 is supported to be steerable left and right by a head pipe 3 at the front end of the body frame 2, and an engine unit 6 is supported by a rear portion of a main frame 5 extending rearward from the head pipe 3 so as to be swingable up and down. A main seat 8 and a tandem seat 8a are mounted on the upper surface of a rear frame 7 that extends obliquely rearward and upward from the main frame 5. A front wheel 9 is supported at the lower end of the front fork 4 and a steering handle 10 is disposed at the upper end. A rear wheel 11 is supported at the rear end portion of the engine unit 6, and a rear wheel suspension cushion unit 12 is disposed between the center portion in the front-rear direction of the engine unit 6 and the front portion of the rear frame 7. Has been. A portion of the body frame 2 extending from the head pipe 3 to the main frame 5 is surrounded by a body cover 13.

  The vehicle body frame 2 is formed by die casting aluminum alloy. More specifically, the left and right frame pieces 2a and 2b constituting the left and right portions in the vehicle width direction are formed by die casting. The left and right frame pieces 2a and 2b are joined together by welding. The mold release directions of the left and right frame pieces 2a and 2b are set in the vehicle width direction.

  The left and right frame pieces 2a and 2b include the left and right head piece portions 3a and 3b constituting the head pipe 3 portion, the left and right main piece portions 5a and 5b constituting the main frame 5 portion, and the above The left and right rear piece parts 7a and 7b constituting the rear frame 7 are integrally formed.

  The welding operation of the left and right frame pieces 2a and 2b is as follows. First, the left and right frame pieces 2a and 2b are set on a positioning jig, the left and right head piece portions 3a and 3b are brought into contact with each other, Positioning is performed by moving the left and right main piece portions 5a and 5b and the left and right rear piece portions 7a and 7b relative to each other in the vehicle width direction with reference to the right head piece portions 3a and 3b. This welding operation is performed so as to proceed from a portion having a small heat capacity to a portion having a large heat capacity, that is, from a portion having a small thickness or area to a portion having a large thickness or area.

  The rear frame 7 is formed so as to form an annular shape with the upper rear edge 5h of the main frame 5 as a whole when viewed from above (from above). Specifically, the upper rear edge portion 5h of the main frame 5, the left and right rear piece portions 7a, 7b that extend integrally from the rear edge portion 5h rearward, and the rear pieces of the rear piece portions 7a, 7b. The rear end cross portions 7c and 7c that connect the end portions form a substantially rectangular annular opening A that is long in the vehicle front-rear direction. More specifically, the left and right rear piece parts 7a and 7b are positioned so as to be located closer to the rear end cross part 7c after inflating from the rear edge part 5h of the main frame 5 in the vehicle width direction in a plan view. It is slanted, and the vertical dimension is smaller from the front side to the rear side in a side view.

  Front and rear cross portions 7d and 7e are integrally formed on the left and right rear piece portions 7a and 7b of the rear frame 7 so as to extend toward the center of the vehicle, and between the rear cross portion 7e and the rear end cross portion 7c. The lamp support portions 7h, 7h are integrally formed so as to extend toward the vehicle center side. A rear lamp unit (not shown) is attached to the lamp support portion 7h.

  The front cross portions 7d, 7d, the rear cross portions 7e, 7e, the rear end cross portions 7c, 7c, and the lamp support portions 7h, 7h are movable in the vehicle width direction and moved in the front-rear direction. The overlapped portions are impossiblely overlapped, and the overlapped portion is welded. Specifically, each of the left cross portions 7d, 7e, 7c and the lamp port portion 7h is formed with a joint flange portion 7k so as to form a stepped portion, and each right joint edge portion on the inner surface of the joint flange portion 7k. 7m is inserted so that it can be relatively moved in the vehicle width direction and cannot be relatively moved in the vertical direction. And each superposition part is joined by welding.

  The front cross portion 7d has a U-shape with a transverse cross section downward, and a cushion mounting hole 7q is formed on the left front cross portion 7d so as to be located on the vehicle outer side from the vehicle center line L. The upper end of the cushion unit 12 is connected to the mounting hole 7q.

  The space in the opening A of the left and right rear piece portions 7a and 7b is an article storage space, and a front opening A1 formed by the rear edge portion 5h, the left and right rear piece portions 7a and 7b, and the front cross portion 7d. A battery 16a, a fuse box 16b, and the like are accommodated in the interior. In addition, an article storage box (not shown) having a size capable of storing a rain gapper or the like is disposed in the middle opening A2 formed by the front cross portion 7d, the left and right rear piece portions 7a and 7b, and the rear cross portion 7e. The

  The front opening A1 and the middle opening A2 are covered with the main seat 8 so as to be opened and closed. A rear opening A3 formed by the rear cross portion 7e and the rear end cross portion 7c is covered with the tandem seat 8a so as to be opened and closed.

  The outer surfaces of the left and right rear piece portions 7a and 7b are exposed to the outside without being covered with the vehicle body cover 13, and function as exterior parts. The outer surfaces of the left and right rear piece portions 7a and 7b are buffed to give a gloss.

  The main frame 5 includes an inclined portion 5c that extends obliquely downward and rearward of the vehicle from the head pipe 3, a rear portion following the inclined portion 5c, a fuel tank 15 and the like, and a suspension portion 5d that suspends the engine unit 6. And have.

  As shown in FIG. 5, the inclined portion 5c has a closed cross section having a substantially rectangular cross section, and a plurality of reinforcing ribs 5g are integrally formed therein so as to protrude inward in the vehicle width direction. Yes. Further, as shown in FIGS. 6 and 7, the suspension portion 5d has a box shape with an open lower end, and a plurality of reinforcing ribs 5g project inward in the vehicle width direction inside the suspension portion 5d. Are integrally formed.

  The welded joints of the left and right main piece parts 5a and 5b constituting the inclined part 5c and the suspension part 5d have the following structure. A joint flange portion 5e is formed on the opposite edge portion of the left main piece portion 5a so as to form a stepped portion that expands outward in the vertical direction, and the joint edge portion 5f of the right main piece portion 5b is formed inside the joint flange portion 5e. Are arranged so as to be vertically movable so as to be relatively movable in the vehicle width direction and not to be relatively movable in the vertical direction.

  Here, a slight gap d (see FIG. 5B) is provided between the step portion of the joint flange portion 5e and the tip of the joint edge portion 5f. As a result, the joint flange portion 5e and the joint edge portion 5f are relatively movable in the vehicle width direction (e direction) and are not relatively movable in the vertical direction. And the overlap part of the front-end | tip part of the joining flange part 5e of the said left main piece part 5a and the joining edge part 5f of the right main piece part 5b is weld-joined. Reference numeral f indicates a weld bead. The weld bead f extends along the center line L at a position shifted from the vehicle center line L by approximately the width of the joint flange 5e in the vehicle width direction. When the left and right frame pieces 2a and 2b are welded together, the inner end surfaces of the left and right frame pieces 2a and 2b may be in contact with each other and positioned.

  The suspension 5d includes a dome-shaped upper wall 5r welded and joined, vertical walls 5s and 5s extending substantially vertically downward from left and right edges of the upper wall 5r, and the left and right vertical walls 5s and 5s. It has a front vertical wall 5q that integrally connects the front edges and a rear vertical wall 5w that integrally connects the rear edges, and has a box shape having an article storage port 5k that opens downward at the lower end. ing. Pivot portions 5p and 5p having pivot holes 5j are integrally formed at the lower rear ends of the left and right vertical walls 5s and 5s.

  The left and right vertical walls 5 s and 5 s have a vertical dimension and a longitudinal dimension that are larger than those of the main piece portion, and have a generally vertically long rectangular shape. Thereby, the area of the side wall is enlarged, and the rigidity of the main frame 5 in the vertical direction and the front-rear direction is improved. Further, the front vertical wall 5q is formed so as to expand in the vehicle width direction and the vertical direction, and the rear vertical wall 5w is largely curved to avoid interference with the engine unit 6.

  On the left and right vertical walls 5s, 5s, an upper step portion 5t and a lower step portion 5u are formed so as to extend in the vehicle front-rear direction. The upper step portion 5t is formed above the vertical center portion of the vertical wall 5s, and the lower step portion 5u is formed at the substantially vertical center portion.

  The lower part of the left and right vertical walls 5s, 5s with the upper step part 5t as a boundary bulges outward from the upper part in the vehicle width direction, and the lower part with the lower step part 5u as a boundary is the upper part It is indented from the part. As a result, a bulging portion 5v bulging outward from the vertical wall 5s is formed between the step portions 5t and 5u, and the left and right bulging portions 5v extend obliquely upward to extend the left, The right rear piece portions 7a and 7b are substantially continuous.

  Since the bulging portion 5v extending in the vehicle longitudinal direction is formed between the upper and lower step portions 5t and 5u of the left and right vertical walls 5s in this way, the area of the left and right vertical walls 5s is reduced in the front-rear direction and the vertical direction. It is possible to avoid a decrease in surface rigidity when the rigidity is increased by enlarging.

  Here, the vehicle width direction dimension W1 between the left and right lower vertical walls 5s ′ is set to be larger over the entire length in the front-rear direction than the vehicle width direction dimension W2 between the upper vertical walls 5s ″. The interval W1 between the front portions of the wall 5s ′ is narrowed so as to be narrower than the interval W3 between the rear portions (see FIGS. 6 and 7).

  A pair of upper and lower reinforcing ribs 5g are integrally formed on the inner surface of the left and right bulging portions 5v, and the protruding height dimension of each reinforcing rib 5g is substantially equal to the bulging dimension of the bulging portion 5v. Is set to

  The outer surface of the left and right bulged portions 5v is subjected to surface treatment by buffing. As a result, the left and right bulged portions 5v are glossy and function as exterior parts exposed to the outside. Further, the upper and lower vertical walls 5s ″ and 5s ′ remain as cast surfaces, and a part thereof is exposed to the outside.

  The left and right vertical walls 5s and 5s of the suspension part 5d of the main frame 5 are footrest mounting regions, and screw holes 5m 'are formed at the lower ends of the left and right lower wall parts 5s'. A pair of front and rear footrest mounting boss portions 5m having a bulge is formed on the vehicle exterior side. On the outer end surface of each mounting boss portion 5m, there is formed a mounting seat surface 5m ″ that is orthogonal to the mold release direction of the left and right frame pieces 2a, 2b.

  The intervals in the vehicle width direction between the mounting seat surfaces 5m ″ of the front mounting boss portion 5m and the mounting seat surfaces 5m ″ of the rear mounting boss portion 5m are set to be approximately the same size. On the other hand, the distance in the vehicle width direction between the left and right vertical walls 5s is set so that the front side portion is slightly narrowed inward from the rear side portion.

  Footrest support brackets 25 are respectively attached to the front and rear mounting boss portions 5m of the left and right vertical walls 5s as shown in FIGS. A low floor footrest (not shown) is disposed on the upper surface of the support bracket 25. The footrest is formed in a shelf shape in which a part of the vehicle body cover 13 projects outward.

  The left and right support brackets 25 are made of a sheet metal separate from the vehicle body frame 2, and have a rectangular flat plate portion 25b extending in the front-rear direction, and a front edge, an inner edge, and a rear edge of the flat plate portion 25b downward. The structure is provided with front, inner and rear flange portions 25c, 25c 'and 25c. In addition, 25a is a lightening hole.

  The support bracket 25 is fixed to the left and right vertical walls 5s by bolts 26 and 26 screwed from the outside of the vehicle, with the inner flange portion 25c 'abutting against the front and rear mounting boss portions 5m and 5m. Yes.

  The support bracket 25 is configured to absorb the load by being deformed prior to the deformation of the left and right vertical walls 5s of the vehicle body frame 2 when a load that pushes the support bracket 25 upward is applied. . Specifically, the plate thickness and shape of the support bracket 25 are set so that the rigidity of the support bracket 25 with respect to the load is lower than the rigidity with respect to the load of the left and right lower wall portions 5s ′ that are the footrest attachment regions. . Note that the rigidity of the left and right vertical walls 5 s and 5 s is higher than the rigidity of the support bracket 25 by providing the reinforcing member 27 described later. When the support bracket 25 is deformed by a fall or the like, the support bracket 25 can be replaced by removing the bolt 26.

  Between the lower end portions of the left and right vertical walls 5s, 5s, a pair of front and rear mounting boss portions 5i 'having bolt holes 5i are formed in a stepped shape so as to bulge toward the vehicle interior side. On the inner side surface of each mounting boss portion 5i ', a mounting seat surface 5i "perpendicular to the mold release direction of the left and right frame pieces 2a, 2b is formed.

  As shown in FIGS. 8 and 12 to 14, a reinforcing member 27 is disposed at the lower end of the left and right vertical walls 5 s. The lower end portions of the left and right vertical walls 5s are connected to each other by the reinforcing member 27, and the article storage port 5k is substantially covered. Each footrest mounting boss portion 5m is positioned in the vicinity of the lower rear portion of each mounting boss portion 5i ', and the reinforcing member 27 and the support bracket 25 substantially overlap when viewed from the side of the vehicle.

  The reinforcing member 27 is composed of pipe front and rear cross portions 28 and 29 and a wide coupling portion 30 that connects the front and rear cross portions 28 and 29 to each other.

  The fuel tank 15 is mounted on the wide coupling portion 30. The fuel tank 15 has a structure in which a fuel supply port 15a extending upward is formed in an upper wall portion of a tank body 15b having a capacity of 4 to 5 liters. The fuel supply port 15a is formed on the upper wall portion of the suspension portion 5d. It is located in the oil supply opening 5n formed in 5r.

  As shown in FIGS. 8 and 15, a flange-like boss member 34 is welded to the left and right side wall portions of the tank body 15 b, and a rubber damper 35 is attached to the boss member 34. The rubber damper 35 is slightly elastically deformed and pressed against the ribs 5g to prevent the tank body 15b from swinging in the vehicle width direction and the front-rear direction. Here, on the inner side surface of the left and right vertical walls 5s, there are formed a plurality of vertical ribs 5g 'that extend radially from the front and rear mounting bosses 5i' and connect the ribs 5g described above.

  A pair of front and rear mounting plates 36, 36 are fixed to the bottom of the tank body 15b, and a pair of left and right bolts 37 are fixed to each mounting plate 36. The bolts 37 extend downward through the insertion holes 30c formed at the front and rear ends of the wide coupling portion 30 with the collar member 38 interposed therebetween. The tank body 15b has rubber sheets 39a and 39b disposed on the upper and lower surfaces of the wide coupling portion 30, respectively, and the lower plate 40 is brought into contact with the lower rubber sheet 39b, and is tightened with a nut 37a to tighten the wide coupling portion. 30 is fixed.

  Here, in order to assemble the fuel tank 15, the tank main body 15b is attached and fixed to the reinforcing member 27 in advance, and the tank main body 15b is inserted into the article storage port 5k from below the suspension part 5d. The cross portions 28 and 29 are bolted and fixed to the left and right vertical walls 5s.

  Seat plates 32 are welded to both end surfaces of the front and rear cross portions 28 and 29, respectively. The front and rear cross portions 28 and 29 are arranged so that each seat plate 32 is brought into contact with a mounting seat surface 5i ″ of each mounting boss portion 5i ′, and a bolt 33 screwed from the outside of the vehicle is tightened to tighten the left and right vertical portions. It is fixed to the wall 5s.

  The wide coupling portion 30 includes a flat plate portion 30a having a surface extending in the axial direction of the front and rear cross portions 28, 29, that is, in the vehicle width direction, and in a direction perpendicular to the front vertical wall 5q, and the flat plate portion 30a. It has the flange part 30b bent downwardly following the left and right edge parts. The front end surface and the rear end surface of the flat plate portion 30a and the left and right flange portions 30b are welded to the front and rear cross portions 28 and 29, respectively.

  The vehicle width dimension of the flat plate portion 30a is set to be smaller than the vehicle width dimension of the cross portions 28 and 29, so that the space between the left and right side surfaces of the flat plate portion 30a and the inner surface of the left and right vertical wall 5s. A gap s is provided (see FIG. 13).

  According to the present embodiment, a pair of front and rear having a mounting seat surface 5m ″ perpendicular to the die-cutting direction on the left and right lower vertical walls 5s ′ which are footrest mounting regions of the body frame 2 formed by die casting aluminum alloy. The footrest mounting bosses 5m are formed to bulge outward from the vehicle, and the mounting brackets 25 made of sheet metal separate from the vehicle body frame 2 are mounted and fixed to the mounting bosses 5m. This eliminates the need for brackets and reduces the number of parts and manufacturing man-hours.

  In the present embodiment, since the support bracket 25 has a lower rigidity than the body frame 2, when a thrust load is applied to the support bracket 25 at the time of falling, the support bracket 25 is deformed and absorbs the load. Damage to the vehicle body frame 2 can be avoided. As a result, it is only necessary to replace the support bracket 25, and the repair cost on the user side can be reduced.

  In the present embodiment, since the front and rear footrest mounting boss portions 5m are arranged in the vicinity of the front and rear cross portions 28 and 29, the support rigidity of the support bracket 25 can be increased. As a result, it is possible to sufficiently support a load such as when the rider stands on the footrest while the support bracket 25 has low rigidity.

  In the present embodiment, the mounting seat surfaces 5m ″ of the left and right footrest mounting boss portions 5m are set to have the same vehicle width direction interval, and the interval W1 between the front portions of the left and right vertical walls 5s, 5s. Is narrowed to be narrower than the distance W3 between the rear parts, so that the rider's toe space can be widened, and a comfortable riding posture can be obtained. In addition, the structure in which the front side is narrowed between the left and right vertical walls 5s can be easily realized by making the body frame made of die casting.

  According to the present embodiment, the lower ends of the left and right vertical walls 5s, 5s are connected by the reinforcing member 27, and the reinforcing member 27 is connected before and after the left and right vertical walls 5s are connected to each other. 29 and the wide joint portion 30 for joining the cross portions 28 and 29 to each other, and the wide joint portion 30 has a surface extending in the vehicle width direction. 29 can increase the rigidity of the left and right vertical walls 5s in the vehicle width direction, and the wide coupling portion 30 that couples the cross portions 28 and 29 to each other in the longitudinal direction along the surface of the left and right vertical walls 5s. Can be increased. As a result, it is possible to prevent both the left and right vertical walls 5s from being deformed in the vehicle width direction and from being displaced in the front-rear direction when the box-shaped body frame 2 having an open lower end is employed. Also from this point, the structure which deform | transforms the support bracket 25 previously at the time of the said fall can be implement | achieved.

  In the present embodiment, the front and rear portions of the left and right vertical walls 5s extending in the vehicle front-rear direction and the vertical direction are connected to each other by the front and rear cross portions 28 and 29. Therefore, the left and right vertical walls 5s having a wide surface. The rigidity of the lower end opening can be improved.

  In the above embodiment, the case where the left and right vertical walls 5s are coupled by the reinforcing member 27 has been described. However, in the present invention, the front vertical wall 5q and the rear vertical wall 5w of the vehicle body frame 2 are coupled by the reinforcing member. May be. In this case, the front and rear vertical walls are connected by the left and right cross portions, and the left and right cross portions are connected by the wide coupling portion.

  In the present embodiment, since the front edges of the left and right vertical walls 5s are connected by the front vertical wall 5q extending in the vehicle width direction and the vertical direction, the rigidity of the lower end opening of the body frame 2 can be further improved.

  In the present embodiment, the front and rear cross portions 28 and 29 are made of pipe, the wide joint portion 30 has a flat plate portion 30a that extends in the vehicle width direction, and the left and right end surfaces of the flat plate portion 30a; Since the gap s is provided between the inner surfaces of the lower end portions of the left and right vertical walls 5s, the rigidity of the left and right vertical walls 5s in the front-rear direction can be further improved.

  In the present embodiment, the left and right frame pieces 2a and 2b made of casting divided into left and right are welded together, and the left and right frame pieces 2a and 2b are left on the left and right inner walls of the right vertical wall 5s. Since the mounting boss portion 5i ′ having the mounting seat surface 5i ″ substantially perpendicular to the direction is formed, the mounting boss portion 5i ′ can be easily formed, and the front and rear cross portions 28 and 29 are provided on the left and right vertical walls. A separate part for attaching to s can be eliminated.

  In this embodiment, since the fuel tank 15 is mounted on the flat plate portion 30a in the left and right vertical walls 5s, the high-rigidity flat plate portion 30a connected to the front and rear cross portions 28 and 29 is effectively used. The heavy fuel tank 15 can be supported, and support by separate parts can be eliminated.

  In the above embodiment, the case where the left and right vertical walls are used as opposing walls and the front vertical wall is used as a connection wall has been described. However, the scope of application of the present invention is not limited to the above. . For example, as shown in FIG. 16, the present invention can also be applied to a structure having front and rear vertical walls 5q and 5w as opposing walls and a lower horizontal wall 5r as a connection wall. In this case, the left ends of the front and rear vertical walls 5q and 5w are opened, and a reinforcing member 27 'is disposed so as to cover the open portion 5s.

1 is a side view of a motorcycle according to an embodiment of the present invention. It is a side view of the body frame of the motorcycle. It is a perspective view of the body frame. It is a top view of the said vehicle body frame. It is sectional drawing of the welding part of the main frame of the said vehicle body frame. It is sectional drawing (the VI-VI line sectional drawing of FIG. 2) of the suspension part of the said main frame. It is sectional drawing (VII-VII sectional view taken on the line of FIG. 2) of the said suspension part. It is a side view of the said main frame. It is sectional drawing (the IX-IX sectional view taken on the line of FIG. 8) of the footrest support bracket with which the said main frame was mounted | worn. It is a top view of the said support bracket. It is a side view of the said support bracket. It is principal part sectional drawing (XII-XII sectional view taken on the line of FIG. 8) of the reinforcement member of the said main frame. It is a top view of the said reinforcement member. It is a side view of the said reinforcement member. Sectional view of the fuel tank mounted on the reinforcing member (XIII-XII in Fig. 8) It is a left view which shows the modification of a reinforcement member arrangement | positioning structure.

I line sectional view).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 2a, 2b Frame piece 5i 'Mounting boss part 5i "Mounting seat surface 5s Left, right vertical wall (opposite wall)
5q front vertical wall (connection wall)
DESCRIPTION OF SYMBOLS 15 Fuel tank 27 Reinforcement member 28 Front cross part 29 Rear cross part 30 Wide joint part 30a Flat plate part s Gap

Claims (7)

  In a motorcycle body frame having a pair of opposing walls that are arranged to face each other and whose ends are open, and a connection wall that connects the opposing walls, the opposing walls are defined as the opposing walls. The reinforcing members are connected by separate reinforcing members, the reinforcing members are connected to the plurality of cross portions connecting the opposing walls, and the cross portions are joined to each other and substantially in the axial direction of the cross portions. A motorcycle body frame comprising a wide coupling portion having a surface extending in a direction perpendicular to the connection wall.   The motorcycle body frame according to claim 1, wherein the reinforcing member is disposed so as to connect ends of the opposing walls.   3. The left and right vertical walls according to claim 1 or 2, wherein the pair of opposing walls of the body frame are left and right vertical walls that are disposed on one side and the other side in the vehicle width direction and extend in the vehicle longitudinal direction and the vertical direction. The lower ends of the walls are opened downward, and the connection wall is a front vertical wall that integrally connects the front edges of the left and right vertical walls, and the lower ends of the left and right vertical walls. A body frame of a motorcycle, wherein front parts and rear parts of the motorcycle are connected by front and rear cross parts.   4. The front and rear cross portions according to claim 3, wherein the front and rear cross pipes are made of pipes, and the wide coupling portion is made of a flat plate connecting the front and rear cross pipes. The body frame of a motorcycle.   The motorcycle body frame according to claim 4, wherein gaps are provided between the left and right edge portions of the flat plate and the inner surfaces of the lower end portions of the left and right vertical walls.   4. The vehicle body frame according to claim 3, wherein the left and right cast frame parts divided into left and right are welded and joined together, and the cross portion is attached to the inner surfaces of the left and right vertical walls. A body frame for a motorcycle, wherein a boss portion is formed, and the mounting boss portion has a mounting seat surface substantially perpendicular to a die-cutting direction during casting.   6. The motorcycle body frame according to claim 4 or 5, wherein a fuel tank is mounted on a flat plate connecting the front and rear cross pipes in the body frame.

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