JP2012071800A - Body frame for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a body frame for a motorcycle capable of securing sufficient rigidity, even with a simple structure.SOLUTION: A main frame 5 extending backward from a head pipe 4 is composed of an upper main frame 8 connected to a top section of the head pipe 4 and extended backward and a lower main frame 9 connected to a bottom section of the head pipe 4 and extended downward and further extended downward behind an engine. In this case, the upper main frame 8 and the lower main frame 9 are joined by being brought close to each other as they are extended backward from the head pipe 4 and branched after forming a joint section 32 of a prescribed length.

Description

  The present invention relates to a body frame of a motorcycle.

  The body frame of a motorcycle has a truss shape by connecting two or more subframes between the two frames that are aligned in the vertical direction and extend rearward in a substantially parallel state. There is what is configured (see Patent Document 1).

JP-A-61-263881

  The truss-shaped vehicle body frame as disclosed in Patent Document 1 can ensure rigidity, but the structure is complicated and the number of frame components is very large.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a body frame of a motorcycle that can ensure sufficient rigidity while having a simple structure.

  As a means for solving the above-mentioned problems, the invention according to claim 1 is directed to a head pipe (4) pivotally supporting a steering shaft (21) and a pair of left and right main frames (5) extending rearward from the head pipe (4). A main body frame of a motorcycle mounted with an internal combustion engine (12), wherein the main frame (5) is coupled to an upper portion of the head pipe (4) and extends rearward, A lower main frame (9) coupled to a lower portion of the head pipe (4) and extending rearward, and extending downwardly behind the internal combustion engine (12). The upper main frame (8) and the lower main frame (8) As the main frame (9) extends rearward from the head pipe (4), the main frame (9) comes close to each other and joins to form a joint (32) having a predetermined length, and then branches. The upper main frame (8) extends rearwardly, the lower main frame (9) is characterized in that it is formed so as to extend rearward of the internal combustion engine (12) extends downwardly.

  The invention according to claim 2 is the body frame of the motorcycle according to claim 1, wherein the projected area of the upper main frame (8) is smaller than the projected area of the lower main frame (9), The lower main frame (8) supports the internal combustion engine (12) and is provided with a shock absorber (30).

  According to a third aspect of the present invention, in the vehicle body frame of the motorcycle according to the first or second aspect, the upper main frame (8) is positioned more inside the vehicle body than the lower main frame (9) in plan view. The cross section of the joint part (32) has a C-shape.

  According to a fourth aspect of the present invention, in the body frame of the motorcycle according to any one of the first to third aspects, the internal combustion engine (12) is located above the crankcase (13) and the crankcase (13). The internal combustion engine (12) is mounted so that the joint (32) is positioned above the cylinder (14) of the internal combustion engine (12). It is characterized by.

  According to a fifth aspect of the present invention, in the motorcycle body frame according to the fourth aspect, the electric box (51) for supporting the fuel tank (25) above the upper main frame (8) and storing the electrical components. ) Is supported between the cylinder (14) and the fuel tank (25) at a position overlapping the joint (32) in a side view.

  According to a sixth aspect of the present invention, in the body frame of the motorcycle according to the fifth aspect, the wiring (59) is passed through the space between the joint portion (32) and the electrical box (51), and It is characterized in that the wiring (59) is held between the upper main frame (8) and the lower main frame (9).

  According to a seventh aspect of the present invention, in the motorcycle body frame according to any one of the first to sixth aspects, the rear main body (8) is coupled to the rear end of the motorcycle main body (8) and extends rearward. A seat frame (7) bent obliquely upward, a rear subframe (10) installed between the lower main frame (9) and a rear end of the seat frame (7), and the seat frame (7) And a reinforcing frame (11) installed between the vicinity of the bent portion of the rear subframe (10) and the vicinity of the connecting portion of the rear sub-frame (10) to the lower main frame (9).

  The invention according to claim 8 is the vehicle body frame of the motorcycle according to any one of claims 1 to 7, and is installed between the left and right lower main frames (9) behind the joint (32). The first cross member (40) having a shock absorber mounting portion (43) and the lower main frame (9) between the left and right lower main frames (9) behind the first cross member (40). 33), and a tension pipe (42) constructed between the first cross member (40) and the second cross member (41). It is characterized by.

  The invention according to claim 9 is the vehicle body frame of the motorcycle according to any one of claims 1 to 8, wherein the upper main frame (8) and the lower main frame (9) are arranged in plan view. A first widened portion (70, 73) that widens rearward from the head pipe (4) in the vehicle width direction, and a straight line from the rear of the first widened portion (70, 73) to the inner side in the vehicle width direction. A gradually decreasing portion (71, 74) that gradually decreases and a second expanding portion (72, 75) that again expands outward from the rear side of the gradually decreasing portion (71, 74) in the vehicle width direction. 32) is characterized in that it is provided between the gradually decreasing portions (71, 74) in the front-rear direction.

  According to a tenth aspect of the present invention, in the body frame of the motorcycle according to the fourth aspect, at least one of the joint portions (32) of the left and right main frames (5) is included in the cylinder (14). The head cover (17) or the cylinder head (16) overlaps with the outer end in the width direction at the top and bottom.

  The invention according to claim 11 is the body frame of the motorcycle according to claim 8, further comprising a down frame (6) extending rearward and downward from the head pipe (4), wherein the engine (12) It is supported by a down frame (6), the engine hanger (33), and a rear end of the lower main frame (9).

According to the first aspect of the present invention, the upper main frame and the lower main frame are joined close to each other as they extend rearward from the head pipe. While forming a truss and supporting the head pipe firmly at the top and bottom, the vertical cross section of the main frame can be secured at the joint and the vertical rigidity can be improved. In addition to improving the layout flexibility of the tank and internal combustion engine, the number of welding points can be reduced.
According to the second aspect of the invention, it is possible to reduce the weight of the upper main frame while supporting the internal combustion engine and securing the rigidity of the lower main frame that bears the load from the ground via the shock absorber. In addition, by providing a size difference in the outer shape of each frame, it is possible to secure an entry space for the welding gun and easily weld the joint.
According to the third aspect of the present invention, the main frame has a downwardly expanding shape, and it is possible to improve the rider's straddling property while securing a space for arranging the internal combustion engine or the like.
According to the invention described in claim 4, since the main frame is formed narrow in the vertical direction when viewed from the side, it is easy to access the head cover, the cylinder head, the spark plug, and the like included in the cylinder located below the main frame. , Maintenance can be improved.
According to the invention described in claim 5, since the side of the electrical equipment box is covered with the upper main frame and the lower main frame, the electrical equipment box can be protected.
According to the sixth aspect of the present invention, the number of holders such as wiring clamps can be reduced.
According to the seventh aspect of the invention, the frame rigidity can be increased.
According to the eighth aspect of the present invention, it is possible to counteract and cancel the inertia force applied from the engine and the force applied from the shock absorber by the road surface reaction force with respect to the lower main frame, and the load applied to the lower main frame. Can be reduced.
According to the ninth aspect of the present invention, since the joining portion is provided in the gradual decreasing portion that is linear and can secure the longest length, rigidity can be ensured and welding is easy.
According to the invention described in claim 10, the frame can be arranged above the engine, the vehicle width can be reduced, and the engine can be easily maintained.
According to the eleventh aspect of the present invention, since the engine does not have an attachment portion to the vehicle body frame above, the upper portion of the engine is accessed from below the joint portion, and the head cover and the like can be easily attached and detached.

1 is a left side view of a motorcycle equipped with a body frame according to an embodiment of the present invention. It is a left view of a vehicle body frame. It is a top view of a vehicle body frame. It is a rear view of a vehicle body frame. It is a perspective view of a body frame. It is sectional drawing which follows the AA line of FIG. 1 is an enlarged view of a main part of a motorcycle. It is a figure explaining the electrical equipment mounted in a motorcycle. It is a figure explaining the electrical equipment mounted in a motorcycle. It is sectional drawing which follows the BB line of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings used below, arrow FR indicates the front of the vehicle, arrow UP indicates the upper side of the vehicle, and arrow LH indicates the left side of the vehicle.

  A motorcycle 1 according to this embodiment is mounted on a motorcycle 1 shown in FIG. In the motorcycle 1, the body frame 2 includes a head pipe 4 that rotatably supports a pair of left and right front forks 3, a pair of left and right main frames 5 that extend rearward from the head pipe 4, and a down frame that extends downward from the head pipe 4. 6 and a seat frame 7 extending obliquely rearward and upward from the rear end of the main frame 5.

  The main frame 5 includes a pair of left and right upper main frames 8 coupled to the upper portion of the head pipe 4 and extending rearward, and a pair of left and right lower main frames 9 coupled to the lower portion of the head pipe 4 and extending rearward and extending downward. It is configured. The upper main frame 8 and the lower main frame 9 are formed of a pipe material made of an aluminum alloy.

  The seat frame 7 is fitted and welded to the rear end of the upper main frame 8 and extends rearward in a substantially horizontal direction, and is bent obliquely upward in the middle. A rear subframe 10 is welded between the lower portion of the lower main frame 9 and the rear end of the seat frame 7. A reinforcing frame 11 is installed between the vicinity of the bent portion of the seat frame 7 and the vicinity of the joint portion of the rear subframe 10 with the lower main frame 9. The seat frame 7, the rear sub frame 10, and the reinforcing frame 11 are formed of a pipe material made of an aluminum alloy.

  In the motorcycle 1, the engine 12 is supported by the down frame 6 and the lower main frame 9. The engine 12 includes a crankcase 13 and a cylinder 14 that extends upward from the crankcase 13. The front part of the crankcase 13 is supported at the lower part of the down frame 6, and the rear part of the crankcase 13 is supported at the lower part of the lower main frame 9. The lower main frame 9 is curved from above the rear part of the engine 12 and extends downward at the rear of the engine 12.

  The cylinder 14 of the engine 12 includes a cylinder block 15, a cylinder head 16 above the cylinder block 15, and a head cover 17 that covers the cylinder head 16. An exhaust pipe 18 is drawn out from the front portion of the cylinder block 15 and is curved and extends rearward. A silencer 19 is connected to the rear end of the exhaust pipe 18. The cylinder head 16 is provided with a spark plug or the like.

  The front wheel 20 is rotatably supported at the lower portion of the front fork 3 that is rotatably supported by the head pipe 4. Specifically, the front fork 3 is rotatably supported by the head pipe 4 via the steering shaft 21. A steering handle 21 </ b> A is provided on the upper portion of the front fork 3. Further, in front of the head pipe 4, a headlight 22, a blinker 23, a meter panel 24 including a plurality of instruments, and the like are disposed.

  A fuel tank 25 is disposed behind the head pipe 4 and above the upper main frame 8, and a seat 26 on which an occupant is seated is disposed behind the fuel tank 25. The fuel tank 25 is supported by the upper main frame 8. The seat 26 is supported by the seat frame 7. The rear wheel 27 is rotatably supported at the rear end of the swing arm 28, and the front end of the swing arm 28 is supported at the lower part of the lower main frame 9 through a pivot shaft 29 so as to be swingable in the vertical direction. A cushion unit 30 that is a shock absorber is interposed between the swing arm 28 and the lower main frame 9.

  As shown in FIGS. 2 to 5, in the vehicle body frame 2, the front end of the upper main frame 8 is welded to the upper portion of the head pipe 4. A pair of left and right gusset plates 31 are welded between the lower peripheral surface of the head pipe 4 and the upper region of the down frame 6, and the front end of the lower main frame 9 is welded to the gusset plate 31. Is bound to. The upper main frame 8 and the lower main frame 9 approach each other as they extend rearward from the head pipe 4, contact each other by a predetermined length, and extend rearward. Are joined together to form a joint 32 having a predetermined length. The joint portion 32 shows the entire region where the upper main frame 8 and the lower main frame 9 are welded together.

  The upper main frame 8 and the lower main frame 9 branch from the rear end of the joint portion 32, and the upper main frame 8 is formed to extend rearward in a substantially horizontal direction, while the lower main frame 9 is formed of the joint portion 32. The rear end of the engine 12 is formed so as to extend downward from the rear end. The lower main frame 9 has an upwardly curved shape. The vertical width of the joint portion 32 is made smaller than the vertical width between the upper main frame 8 and the lower main frame 9 positioned before and after the joint portion 32.

  Referring to FIG. 3, the upper main frame 8 includes an upper first expanding portion 70 that expands rearward from the head pipe 4 in the vehicle width direction in a plan view (top view), and the upper first expanding portion 70. It is formed to have an upper gradually decreasing portion 71 whose width gradually decreases linearly from the rear to the inner side in the vehicle width direction, and a lower second expanding portion 72 that expands again from the rear of the upper gradually decreasing portion 71 to the outer side in the vehicle width direction. ing. The lower main frame 9 includes a lower first expanding portion 73 that extends rearward from the head pipe 4 outward in the vehicle width direction in plan view (top view), and an inner side in the vehicle width direction from the rear of the lower first expanding portion 73. The lower gradually decreasing portion 74 whose width gradually decreases linearly and the lower second expanding portion 75 which expands again from the rear side of the lower gradually decreasing portion 74 outward in the vehicle width direction are formed. Here, the joint portion 32 is provided across the upper gradually decreasing portion 71 and the lower gradually decreasing portion 74 that are integrated.

  The upper main frame 8 is formed with a diameter smaller than that of the lower main frame 9. As is apparent from FIG. 6 (cross section taken along line AA in FIG. 2), the projected area of the vertical cross section of the upper main frame 8 is It is formed smaller than the projected area of the vertical cross section. The projected area refers to the area of a portion including a hollow portion and a thick portion in the circular cross section of the upper main frame 8 and the lower main frame 9. In the present embodiment, the lower main frame 9 has a diameter larger than that of the upper main frame 8, and the cross-sectional area of the lower main frame 9 is made larger than the cross-sectional area of the upper main frame 8, thereby ensuring the rigidity of the lower main frame 9. The upper main frame 8 is reduced in weight.

  As shown in FIG. 3, the upper main frame 8 is disposed on the inner side of the vehicle body with respect to the lower main frame 9 in a plan view, and the cross section of the joint portion 32 has a square shape as shown in FIG. 6. Here, as shown in FIG. 7, the engine 12 is mounted on the vehicle body frame 2 such that the joint portion 32 is positioned above the cylinder 14 when mounted on the vehicle body frame 2. In addition, the code | symbol 32a has shown the welding part in FIG.

  As shown in FIGS. 3 and 4, a front fuel tank support bracket 35 is welded to the front portion of the upper main frame 8 so as to straddle the pair of left and right upper main frames 8. An upper class member 37 having a tank support bracket 36 is installed. As shown in FIGS. 8 and 9, a bolt insertion hole 38 is formed in the front fuel tank support bracket 35, and the front portion of the fuel tank 25 is fastened to the bolt insertion hole 38. Further, the rear fuel tank support bracket 36 is a pipe-like member extending in the axial direction in the vehicle width direction, and rotatably supports the fuel tank rear stay 39 that engages the rear portion of the fuel tank 25.

  As shown in FIG. 10, when viewed in the vertical direction, the right joint portion 32 of the joint portions 32 of the left and right main frames 5 is the right end portion 17 </ b> A in the width direction of the head cover 17 and the right end portion in the width direction of the cylinder head 16. It overlaps with the part 16A vertically (positioned so as to overlap). In this embodiment, only the right joint 32 overlaps the widthwise outer ends of the head cover 17 and the cylinder 14 in the vertical direction. However, both joints 32 may overlap depending on the outer shape of the engine. You may make it overlap with either 17 and the cylinder 14. FIG.

  With reference to FIGS. 8, 9, and 10, when the vehicle body frame 2 according to the present embodiment is mounted on the motorcycle 1, an electrical box 51 that houses electrical components is disposed between the left and right main frames 5. The electrical box 51 includes a plate member 52 (FIG. 9) on which electrical components are mounted and a cover member 53 that covers the electrical components mounted on the plate member 52. FIG. 9 shows a state where the cover member 53 is removed from the state shown in FIG.

  The plate member 52 shown in FIG. 9 is fastened to the lower surface of the lower main frame 9 above the cylinder 14, and a bolt fastening hole (not shown) is formed in the lower main frame 9. A pair of left and right fixing brackets 54 are welded to the upper surface of the upper main frame 8, and the cover member 53 is fastened and fixed by the fixing brackets 54.

  In this example, a starter magnet 55, a battery 56, a fuse box 57, and the like are mounted on the plate member 52. The battery 56 is held by a holding plate 58 provided so as to straddle the left and right of the upper main frame 8 above the battery 56, and the holding plate 58 is also fixed by the fixing bracket 54. That is, the cover member 53 is fastened and fixed to the fixing bracket 54 with the holding plate 58 being fastened together.

  In the lower main frame 9, as shown in FIGS. 3 to 5, the first cross member 40 straddling the left and right behind the joint portion 32, and the first cross member straddling the left and right behind the first cross member and below the first cross member. Two cross members 41 are installed. A tension pipe 42 extending in the vertical direction is installed between the first cross member 40 and the second cross member 41.

  The first cross member 40 has a half-split structure (so-called middle structure), and the left and right ends of each half are welded to the left and right lower main frames 9. A shock absorber mounting portion 43 for fixing the upper end of the cushion unit 30 is welded to the rear surface of the first cross member 40, and a mounting seat surface 45 for attaching the regulator 44 to the front surface of the first cross member 40 as shown in FIG. Is provided. Since the first cross member 40 has a hollow middle structure, the shock absorber mounting portion 43 can be easily welded and the regulator 44 can be fixed easily. As shown in FIG. 7, the upper end of the cushion unit 30 is fixed to the shock absorber mounting portion 43, and the regulator 44 is mounted on the mounting seat surface 45.

  As shown in FIG. 2, an engine hanger 33 that supports the crankcase 13 is welded to the front portion of the second cross member 41 so as to protrude forward and downward. A pair of left and right support bosses 34 that protrude outward in the vehicle width direction and support the crankcase 13 are provided below the down frame 6. As shown in FIG. 6, the rear portion of the crankcase 13 is fastened and fixed to the engine hanger 33, and the front portion of the crankcase 13 is fastened and fixed to the support boss 34 via the plate member 34a. Supported by

  A pair of left and right pivot plates 47 having a shaft hole 46 through which the pivot shaft 29 is inserted are welded to the lower end of the lower main frame 9. The upper portion of the pivot plate 47 is welded to the front portion of the rear subframe 10 and is formed to extend rearward and obliquely upward. The rear subframe 10 is welded with a pair of left and right step frames 48 that support steps for passengers to put their legs on.

  The reinforcement frame 11 extends rearward and obliquely upward from the vicinity of the welded portion of the step frame 48 and is welded to the seat frame 7. A first rear cross member 49 is installed substantially at the center of the seat frame 7 in the front-rear direction, and a second rear cross member 50 is installed at the rear of the seat frame 7.

  Further, when the electrical box 51 is arranged between the main frames 5 as shown in FIGS. 8 and 9, the electrical box 51 is located between the cylinder 14 and the fuel tank 25 in a side view as shown in FIG. Therefore, it is supported at a position overlapping the joint portion 32. In this case, as shown in FIGS. 8 and 9, a gap (space) is formed on the left and right between the joint portion 32 and the electrical box 51. The battery 56 and the fuse box 57 are respectively formed in the left and right spaces. Wirings 59, 60, 61 connected to etc. are arranged.

  As shown in FIG. 7, each wiring 59, 60, 61 is inserted into a space formed between the upper main frame 8 and the lower main frame 9 in front of the joint portion 32, and the upper main frame 8 and the lower main frame 9. Extending backwards along. That is, the upper main frame 8 and the lower main frame 9 can function as a wiring clamp (holding tool) by passing the wiring through the front space thereof, and can also function as a guide for guiding the wiring backward. ing.

  As described above, in the vehicle body frame 2 according to the present embodiment, the upper main frame 8 and the lower main frame 9 are joined closer to each other as they extend rearward from the head pipe 4, and a joining portion having a predetermined length. The upper main frame 8 extends rearward and the lower main frame 9 extends downward and extends rearward of the engine 12. For this reason, while having a simple structure, a truss is formed at the front part of the upper main frame 8 and the lower main frame 9, and the head pipe 4 is firmly supported at the top and bottom, and the longitudinal section of the main frame 5 is formed at the joint 32. It can be secured and the longitudinal rigidity can be improved. Moreover, the vertical width of the main frame 5 can be made compact, the layout flexibility of the fuel tank 25 and the engine 12 can be improved, and the number of welding points can be reduced.

  Further, by forming the projected area of the upper main frame 8 smaller than the projected area of the lower main frame 9, the lower main frame 9 that supports the engine 12 and bears a load from the ground via the cushion unit 30. The upper main frame 8 can be reduced in weight while ensuring rigidity. In addition, by providing a size difference in the outer shape of each frame, it is possible to secure an entry space for the welding gun and easily weld the joint portion 32.

  Further, the upper main frame 8 is positioned on the vehicle body inner side than the lower main frame 9 in a plan view (top view), and the cross section of the joint portion 32 exhibits a square shape, so that the main frame 5 is expanded downward. It becomes a shape, and it is possible to improve the rider's straddling property while securing the arrangement space for the engine 12 and the like.

  In addition, in the vehicle body frame 2, the engine 12 is mounted by the down frame 6 and the lower main frame 9 so that the joint portion 32 is positioned above the cylinder 14 of the engine 12. In this case, since the main frame 5 (joint portion 32) is formed narrow in the vertical direction when viewed from the side, the head cover 17, the cylinder head 16, and the spark plug included in the cylinder 14 positioned below the main frame 5 are easily accessible. And maintainability can be improved.

  Further, in the vehicle body frame 2, the electrical box 51 is supported by the fixing bracket 45 at a position between the cylinder 14 and the fuel tank 25 and overlapping the joint portion 32 in a side view. In this case, since the side of the electrical box 51 is covered with the upper main frame 8 and the lower main frame 9, the electrical box 51 can be protected. At this time, the wirings 59, 60, 61 are passed through the space between the joint portion 32 and the electrical box 51, and the wiring is held between the upper main frame 8 and the lower main frame 9. The number of holders such as clamps can be reduced.

  Further, in the above configuration, the first cross member 40 having the shock absorber mounting portion 43 is installed between the left and right lower main frames 9 at the rear of the joint portion 32, and the rear of the first cross member 40 at the left and right lower A second cross member 41 having an engine hanger 33 is installed between the main frames 9, and a tension pipe 42 is installed between the first cross member 40 and the second cross member 41. According to this, the inertial force applied from the engine 12 and the force applied from the cushion unit 30 can be countered and canceled against the lower main frame 9 by the road surface reaction force, and the load applied to the lower main frame 9 is reduced. it can.

  Further, the upper main frame 8 and the lower main frame 9 are, in plan view, an upper and lower first expanding portion (70, 73) that expands rearward from the head pipe 4 outward in the vehicle width direction, and the upper and lower first expanding portion. (70, 73) Vertically decreasing portion (71, 74) whose width gradually decreases linearly from the rear to the inner side in the vehicle width direction, and upper and lower portions expanding again from the rear of the vertical decreasing portion (71, 74) toward the outer side in the vehicle width direction. Since the joining portion 32 is provided in the gradually decreasing portion that is formed in a straight line and has the longest length, the rigidity can be ensured and welding can be easily performed.

  Further, the right joint portion 32 in the left and right main frames 5 overlaps the right outer end in the width direction of the head cover 17 and the cylinder head 16 included in the cylinder 14, so that the frame is disposed above the engine 12. The vehicle width can be reduced and the engine 12 can be easily maintained. Further, since the engine 12 is supported by the down frame 6, the engine hanger 33, and the rear end of the lower main frame 9, the engine 12 does not have an attachment portion to the vehicle body frame at the upper side. The upper part of the engine 12 is accessed from below, and the head cover 17 and the like can be easily attached and detached.

  In addition, this invention is not limited to the said embodiment. For example, in the above embodiment, each frame constituting the vehicle body frame 1 is made of a pipe material having a circular cross section, but may be made of a pipe material having a rectangular cross section, a member having a U-shaped cross section, or the like. .

1 Motorcycle 4 Head Pipe 5 Main Frame 7 Seat Frame 8 Upper Main Frame 9 Lower Main Frame 10 Rear Subframe 11 Reinforcement Frame 12 Engine (Internal Combustion Engine)
13 Crankcase 14 Cylinder 21 Steering shaft 25 Fuel tank 30 Cushion unit (buffer)
32 Joint portion 33 Engine hanger 40 First cross member 41 Second cross member 42 Tension pipe 43 Shock absorber mounting portion 51 Electrical box 59 to 61 Wiring 70 Upper first expanding portion 71 Upper gradually decreasing portion 72 Upper second expanding portion 73 Lower first expanding portion 74 Lower gradually decreasing portion 75 Lower second expanding portion

Claims (11)

A vehicle body of a motorcycle having an internal combustion engine (12), comprising a head pipe (4) pivotally supporting the steering shaft (21) and a pair of left and right main frames (5) extending rearward from the head pipe (4). In the frame,
After the main frame (5) is coupled to the upper portion of the head pipe (4) and extends rearward, the main frame (5) is coupled to the lower portion of the head pipe (4) and extends rearward, and then the internal combustion engine. A lower main frame (9) extending downward at the rear of (12),
After the upper main frame (8) and the lower main frame (9) are joined to each other as they extend rearward from the head pipe (4) to form a joint portion (32) having a predetermined length. The motorcycle is formed to be branched, and the upper main frame (8) extends rearward, and the lower main frame (9) extends downward and extends rearward of the internal combustion engine (12). Body frame. A projected area of the upper main frame (8) is smaller than a projected area of the lower main frame (9);
The body frame of the motorcycle according to claim 1, wherein the internal combustion engine (12) is supported by the lower main frame (8) and a shock absorber (30) is attached.   The said upper main frame (8) is located in a vehicle body inner side rather than the said lower main frame (9) by planar view, The cross section of the said junction part (32) exhibits a C-shape. Or a body frame of the motorcycle according to 2;   The internal combustion engine (12) has a crankcase (13) and a cylinder (14) extending upward from the crankcase (13), and the joint portion is located above the cylinder (14) of the internal combustion engine (12). The body frame of the motorcycle according to any one of claims 1 to 3, wherein the internal combustion engine (12) is mounted so that (32) is positioned.   An electrical box (51) that supports the fuel tank (25) above the upper main frame (8) and accommodates electrical components is disposed between the cylinder (14) and the fuel tank (25), The body frame of the motorcycle according to claim 4, wherein the body frame is supported at a position overlapping with the joint portion (32) in a side view.   The wiring (59) is passed through the space between the joint (32) and the electrical box (51), and the wiring (59) is provided between the upper main frame (8) and the lower main frame (9). The body frame of the motorcycle according to claim 5, wherein the body frame is held through. A seat frame (7) that is fitted and joined to the rear end of the upper main frame (8), welded, extends rearward, and bends obliquely upward from the middle;
A rear subframe (10) welded between the lower main frame (9) and the rear end of the seat frame (7);
A reinforcing frame (11) installed between the vicinity of the bent portion of the seat frame (7) and the vicinity of the joint portion of the rear subframe (10) with the lower main frame (9). The body frame of the motorcycle according to any one of claims 1 to 6. A first cross member (40) provided between the left and right lower main frames (9) behind the joint (32) and having a shock absorber mounting portion (43);
A second cross member (41) having an engine hanger (33) provided between the left and right lower main frames (9) behind the first cross member (40);
The tension pipe (42) installed between the first cross member (40) and the second cross member (41), and the tension pipe (42). The body frame of a motorcycle.   The upper main frame (8) and the lower main frame (9) have a first widened portion (70, 73) widened rearward from the head pipe (4) in the vehicle width direction in plan view, A gradually decreasing portion (71, 74) in which the width gradually decreases linearly from the rear of the first expanding portion (70, 73) to the inner side in the vehicle width direction, and expands again from the rear of the gradually decreasing portion (71, 74) to the outer side in the vehicle width direction. A second expanding portion (72, 75) that opens, and the joint portion (32) is provided across the gradually decreasing portion (71, 74) in the front-rear direction. The body frame of the motorcycle according to any one of the above.   At least one of the joint portions (32) of the left and right main frames (5) overlaps the outer end in the width direction of the head cover (17) or the cylinder head (16) included in the cylinder (14) vertically. The motorcycle body frame according to claim 4, wherein the motorcycle body frame is provided. A down frame (6) extending rearward and downward from the head pipe (4);
The automatic engine according to claim 8, wherein the engine (12) is supported by the down frame (6), the engine hanger (33), and a rear end of the lower main frame (9). Body frame for motorcycles.

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