JP2013006532A - Frame of motorcycle and motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motorcycle that can improve strength of a joining place of a main tube and a body tube.SOLUTION: The main tube 52 is formed with a front side inclined part 521 drawing by inclining backward-downward, and a curved part 522 curved substantially downward by continuing from the rear end of the front side inclined part 521. The right-left body tubes 8 are formed with a joining part 85 joined in the boundary vicinity between the front side inclined part 521 and the curved part 522 of the main tube 52, a first bending part 81 bending in the vehicle width direction and unbending in the vertical direction in the rear end vicinity of the joining part 85, and a second bending part 82 bending in the vertical direction in a position separated backward from the first bending part 81. The center line Cbetween the joining part 85 and the second bending part 82 in a side view, is substantially parallel to the center line Cof the front side inclined part 521 of the main tube 52.

Description

  The present invention relates to a motorcycle frame and a motorcycle. Specifically, the present invention relates to a motorcycle frame configured by joining a plurality of metal members, and a motorcycle including the frame.

  Some motorcycle frames include a head pipe, a main tube, a body tube, and a down tube. The head pipe is a tubular portion that tilts backward, and is a portion to which a steering device including a front wheel and a handle is rotatably connected. The main tube is a portion whose front end is joined to the head pipe and extends obliquely downward and rearward from the head pipe. The down tube has a portion that extends downward from the rear portion of the head pipe, and a portion that extends rearward from the lower end of this portion and joins the main tube. The body tube is a portion extending substantially rearward from the main tube. A seating seat is attached to the upper side of the body tube via a seat rail. These head pipe, main tube, down tube, and body tube are generally formed of a steel material and are welded together to form a frame.

  Each member constituting the frame is generally a pipe-like member. As a configuration for welding the pipe-shaped member, for example, as described in Patent Document 1, there is a configuration in which the end of one member is abutted against the other member and welded. Further, as described in Patent Document 2, there is a configuration in which the end of one member is crushed according to the shape of the surface of the other member, and the crushed portion is overlapped and welded to the surface of the other member.

JP 2005-82033 A JP 2002-193173 A

  However, these configurations have the following problems. In the configuration in which the end of one member is abutted against the surface of the other member and welded, it is difficult to increase the welding length. For this reason, the stress concerning a welding part becomes large. Moreover, since the shape of the welded portion tends to be complicated, the workability of welding is low. Furthermore, it is necessary to form the end of one member in a shape that follows the surface of the other member. For this reason, since complicated machining is required at the end of one member, the productivity of the frame of the motorcycle is lowered. Moreover, in the structure which crushes and welds the edge part of one member, the dimension and shape of a cross section change rapidly in the boundary of the part crushed and the part which is not crushed. For this reason, stress concentrates in the vicinity of this boundary. If it does so, it will become difficult to ensure the strength of the crushed member. Furthermore, when the center line of one member and the center line of the other member are not parallel, the portion to be crushed is bent at the boundary between the portion to be crushed and the portion not to be crushed so as to overlap the surface of the other member. Sometimes. Since stress concentrates in the bent portion, it is difficult to ensure strength.

  Furthermore, as described in Patent Document 2, a configuration in which a body tube that supports a seat is joined to an upper portion of a main tube may be used. In such a configuration, it is necessary to lower the main tube in order to lower the seat and make it easier for the driver to put his feet on the ground. When the main tube is lowered, the area where the engine unit is disposed becomes narrow, and therefore workability such as mounting of the engine unit is deteriorated. Thus, it is difficult to achieve both operability and ride comfort and workability for the engine unit and the like.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a motorcycle frame and a motorcycle capable of improving the strength of the joint. Another problem to be solved by the present invention is to provide a motorcycle frame and a motorcycle capable of improving the strength of the welded portion between the main tube and the body tube. Further, the problem to be solved by the present invention is to improve the operability for the engine unit by maintaining the height of the main tube while lowering the seating seat and improving the operability. To provide a frame and a motorcycle.

  In order to solve the above problems, a motorcycle frame according to the present invention includes a front inclined portion that inclines and extends downward and a curved portion that continuously curves from the rear end of the front inclined portion and curves downward. A main tube to be formed; a joint portion joined in the vicinity of the boundary between the front inclined portion and the curved portion of the main tube; and bent in the vehicle width direction in the vicinity of the rear end of the joint portion and bent in the vertical direction. A first bent portion and a second bent portion bent in the vertical direction at a position spaced rearward from the first bent portion, and the joint portion and the second bent portion in a side view are formed. And a body tube substantially parallel to the center line of the front inclined portion of the main tube.

  The joint portion of the body tube is made of a pipe-like member and is formed by being flattened and flattened.

  The body tube is formed with a portion that extends substantially rearward from the second bent portion and supports a seating seat on which a driver can sit, and the portion that supports the seating seat is more than the joint portion. It has the part formed in a low position, It is characterized by the above-mentioned.

  The body tube has a portion extending substantially horizontally from the second bent portion substantially rearwardly, and a portion inclined rearward from a rear end of the substantially horizontally extending portion. The portion extending in the direction is formed at a position lower than the joint portion.

  The motorcycle according to the present invention includes a frame of the motorcycle.

  The motorcycle of the present invention includes a frame of the motorcycle and a seating seat on which a driver is seated, and a portion of the seating seat on which the driver is seated is from the joint portion of the body tube. Is located above the portion formed at a lower position.

  The motorcycle of the present invention includes a frame of the motorcycle and a seating seat on which a driver is seated, and a portion of the seating seat on which the driver is seated is substantially rearward from the second bent portion. It is located on the upper side of the portion extending substantially horizontally.

  According to the present invention, the body tube is bent only in the left-right direction (= vehicle width direction) at the rear end of the joint and in the vicinity thereof, and is not bent in the up-down direction. For this reason, it can prevent or suppress that stress concentrates by making the change of a cross-sectional dimension and a shape moderate in the rear end of a junction part, and its vicinity. In addition, since the rear end of the joint and its vicinity are not bent in the vertical direction, even when a vertical load is applied to the body tube, the stress in the vertical direction is prevented from concentrating on that part. it can. In this way, stress can be prevented from concentrating on the rear end of the joint portion of the body tube and in the vicinity thereof.

  If the joint portion of the body tube is formed of a pipe-like member and is crushed flat, the joint portion can be easily formed by pressing or the like. For this reason, productivity can be improved. And since it can weld linearly along the direction of a center line, it becomes easy to aim at improvement of joint strength (= welding strength) by lengthening welding length, and improvement of productivity. be able to.

  Since the seating seat can be provided at a position lower than the joint portion of the body tube, the seating seat can be lowered without lowering the vehicle height. And, by lowering the seating seat, it becomes easier for the driver to put his feet on the ground, so operability and riding comfort are improved. Moreover, since it is not necessary to make vehicle height low, it is not necessary to narrow the area | region where an engine unit is mounted. For this reason, it is possible to maintain or improve the degree of freedom of the layout of the engine unit and other predetermined devices. Further, it is possible to maintain or improve workability for the engine unit and other predetermined equipment mounted on the motorcycle.

FIG. 1 is a side view schematically showing the configuration of a motorcycle according to an embodiment of the present invention. FIG. 2A is a plan view schematically showing the configuration of the main frame, and FIG. 2B is a side view schematically showing the configuration of the main frame. FIG. 3 is a perspective view of the joint portion between the body tube and the main tube as viewed obliquely from above and behind. FIG. 4 is a side view of the joint portion between the body tube and the main tube. FIG. 5A is a plan view of the joint portion between the body tube and the main tube as viewed from above, and FIG. 5B is a plan view of the joint portion between the body tube and the main tube as viewed from below. is there. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a side view showing a state in which the engine unit and the rear wheel suspension device are assembled to the frame. FIG. 9 is a plan view showing a state in which the engine unit and the rear wheel suspension device are assembled to the frame.

  Embodiments of the present invention will be described below in detail with reference to the drawings. For convenience of explanation, the frame of the motorcycle according to the embodiment of the present invention is referred to as “main frame”, and the motorcycle to which the present frame is applied is referred to as “main motorcycle”. Also, in the following description, the directions of “front”, “rear”, “upper”, “lower”, “right”, and “left” of the main frame and the motorcycle are based on the direction of the driver who rides the motorcycle. To do. In each figure, “front” is indicated by an arrow Fr, “back” is indicated by an arrow Rr, “upper” is indicated by an arrow Tp, “lower” is indicated by an arrow Bt, “right” is indicated by an arrow R, “Left” is indicated by an arrow L.

  First, the overall configuration of the motorcycle 1 and the frame 5 will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view schematically showing the configuration of the motorcycle 1 as seen from the left side. FIG. 2A is a plan view schematically showing the configuration of the main frame 5 as viewed from above. FIG. 2B is a side view schematically showing the configuration of the main frame 5 as viewed from the left side. As shown in FIG. 1, the motorcycle 1 includes a main frame 5, a steering device 11, an engine unit 12, a rear wheel suspension device 13, and an exhaust device 14 (not visible in FIG. 1). Reference), a fuel tank 15, a seating seat 16, and other predetermined devices and members.

  The steering device 11 includes a steering shaft (not visible in FIG. 1), a handle 111, a pair of left and right front forks 112, and a front wheel 113. And can be rotated. The steering shaft is rotatably supported by the head pipe 51. The handle 111 is provided at the upper end of the steering shaft. The pair of left and right front forks 112 are respectively disposed on the left and right of the steering shaft. The front wheel 113 is rotatably supported by the lower end of the front fork 112. The handle 111 has left and right handle grips. The right handle grip is provided with a throttle grip and a brake lever of the front wheel 113. The left handle grip is provided with a clutch lever for operating the clutch. In addition, the handle 111 is provided with switches for operating lights and horns.

  The engine unit 12 is disposed in a region (see FIG. 2) formed by the main tube 52 and the down tube 53 of the main frame 5. The engine unit 12 includes a cylinder assembly 121, a crankcase assembly 122, and a clutch. The cylinder assembly 121 includes a cylinder block, a cylinder head, and a cylinder head cover. A combustion chamber is formed inside the cylinder block, and a piston is reciprocally disposed. The cylinder head is provided on the upper side of the cylinder block. The cylinder head is formed with an intake port and an exhaust port communicating with the combustion chamber and the outside of the cylinder block. Further, an intake valve that controls opening and closing of the intake port and an exhaust valve that controls opening and closing of the exhaust port are arranged inside the cylinder head. The intake valve is driven by the intake side cam, and the exhaust valve is driven by the exhaust side cam. The cylinder head cover is a member that becomes a lid of the cylinder head, and is disposed on the upper side of the cylinder head. Inside the crankcase assembly 122, a crank chamber is formed on the front side, and a mission chamber is formed on the rear side. A crankshaft is rotatably disposed inside the crank chamber. Inside the mission chamber, a countershaft and a driven shaft are rotatably disposed, and a transmission is provided. The end of the driven shaft protrudes outside the left side of the crankcase. A drive chain sprocket 123 is provided at the end of the driven shaft (not visible in FIG. 1, see FIG. 8). The drive chain sprocket 123 is covered with a sprocket cover 124. In addition, a clutch is disposed on the right side of the crankcase. Further, on the left side of the crankcase and in front of the drive chain sprocket 123, a magnet as a generator and a starter for starting the engine are provided.

  The rear wheel suspension device 13 includes a swing arm 131, a rear cushion unit 132, and a rear wheel 133, and is provided at the rear portion of the frame 5. The swing arm 131 is a member that supports the rear wheel 133 as a drive wheel. A front end portion of the swing arm 131 is coupled to the frame pivot 55 so as to be swingable in the vertical direction. An end piece is provided at the rear end of the swing arm 131. The end piece is a bracket formed in a substantially flat plate shape, and is integrally coupled to the rear end portion of the swing arm 131 by welding or the like. The rear wheel 133 is rotatably supported by the end piece. On the left side of the rear wheel 133, a driven chain sprocket 135 that rotates integrally with the rear wheel 133 is provided. Then, the drive chain 134 is wound around the drive chain sprocket 123 of the engine unit 12 and the driven chain sprocket 135 of the rear wheel 133 (in FIG. 1, it is hidden and cannot be seen) (see FIG. 8). The drive chain 134 and the driven chain sprocket 135 are accommodated in the chain case 136. The chain case 136 is attached to the swing arm 131. The rear cushion unit 132 has a function of mitigating and absorbing vibration and shock transmitted from the rear wheel 133 to the body tube 8. The upper end of the rear cushion unit 132 is rotatably connected to the rear cushion bracket 58, and the lower end is rotatably connected to the end piece.

  The exhaust device 14 includes a silencer 141 and an exhaust pipe 142 (see FIG. 8). The silencer 141 is arranged on the right rear side of the engine unit 12 and on the side of the rear wheel 133. One end of the exhaust pipe 142 is connected to an exhaust port of the cylinder assembly 121 of the engine unit 12. The other end is connected to the front side of the silencer 141. The exhaust pipe 142 is directed forward from the front side of the cylinder assembly 121 of the engine unit 12, is curved rearward at the front side of the cylinder assembly 121, passes through the side of the cylinder assembly 121, and is directed to the front side of the silencer 141. To reach.

  The fuel tank 15 is disposed on the upper side of the front inclined portion 521 of the main tube 52. On the upper side of the body tube 8, a seating seat 16 on which a driver and a passenger are seated is disposed via a seat rail (not shown). Further, a front side cover and a rear side cover are attached to the outside of the motorcycle 1. The positional relationship between the body tube 8 and the seating seat 16 will be described later.

  The configurations of the steering device 11, the engine unit 12, the exhaust device 14, and the rear wheel suspension device 13 are merely examples, and the present invention is not limited to the above configuration.

  Next, the overall configuration of the main frame 5 will be described with reference to FIGS. 1 and 2. As shown in FIGS. 2A and 2B, the frame 5 includes a head pipe 51, a main tube 52, a down tube 53, a pair of left and right body tubes 8, and a pair of left and right side tubes 54. . Further, the frame 5 includes a frame pivot 55, a first reinforcing member 56, a second reinforcing member 57, an engine suspension tube 59, a rear cushion bracket 58, a front cross member 60, and an intermediate cross. A member 61 and a rear cross member 62 are provided. And these frames 5 are comprised by welding these members.

  The head pipe 51 is a cylindrical member that tilts backward. As described above, the steering device 11 is rotatably attached to the head pipe 51.

  The main tube 52 is a pipe-like member, and is provided at the approximate center in the left-right direction (= vehicle width direction) of the main frame 5 and the main motorcycle 1. The front end (= upper end) of the main tube 52 is joined to the rear upper part of the head pipe 51. The main tube 52 as a whole is inclined rearwardly downward from the front end toward the rear end (= lower end). Specifically, as shown in FIG. 2, the main tube 52 includes a front inclined portion 521, a curved portion 522, and a rear inclined portion 523. The front inclined portion 521 is a portion that is formed in a substantially straight line, and is a portion that is inclined rearwardly downward from the rear upper portion of the head pipe 51 toward the rear obliquely downward. The curved portion 522 is a portion that continues from the rear end (= lower end) of the front inclined portion 521, and is a portion that curves with a predetermined curvature substantially downward. The rear inclined portion 523 is a portion that is formed in a substantially straight line, and is a portion that is inclined rearwardly downward from the rear end (= lower end) of the curved portion 522 toward the rear obliquely downward. Note that the inclination angle of the rear inclined portion 523 is tighter than the inclination angle of the front inclined portion 521. As described above, the main tube 52 has a configuration in which a curved portion 522 that is curved substantially downward is formed on the rear side of the front inclined portion 521 that is inclined at a predetermined angle.

  The down tube 53 is a pipe-like member, and is provided substantially at the center in the left-right direction (= vehicle width direction) of the main frame 5 and the main motorcycle 1. The front end (= upper end) of the down tube 53 is joined to the rear inclined portion 523 of the head pipe 51, and the rear end (= lower end) is joined to the rear end (= lower end) of the rear inclined portion 523 of the main tube 52. The The front portion (= upper portion) of the down tube 53 is inclined rearward and downward with a tighter inclination angle than the front inclined portion 521 of the main tube 52 with respect to the horizontal direction. The rear part (= lower part) of the down tube 53 extends substantially horizontally. And between the part which inclines backward and the part extended substantially horizontally, it is curving with a predetermined curvature.

  The first reinforcing member 56 is joined across the head pipe 51, the front end portion of the main tube 52, and the front end portion of the down tube 53. A flat plate member is applied to the first reinforcing member 56. The first reinforcing member 56 improves the bonding strength of the head pipe 51, the main tube 52, and the down tube 53. Further, an engine suspension tube 59 is provided between the vicinity of the rear end of the front inclined portion 521 of the main tube 52 (= the vicinity of the boundary between the front inclined portion 521 and the curved portion 522) and the first reinforcing member 56. . For example, a pipe-shaped member is applied to the engine suspension tube 59. A space for disposing the engine unit 12 is formed in a region surrounded by the main tube 52 and the down tube 53 of the frame 5.

  In addition, a frame pivot 55 is provided in the vicinity of the joint portion between the rear end of the rear inclined portion 523 of the main tube 52 and the rear end of the down tube 53. The frame pivot 55 is a member to which the front end portion of the swing arm 131 of the rear wheel suspension device 13 is pivotably connected.

  The left and right body tubes 8 are pipe-shaped members. The left and right body tubes 8 have a function of supporting a seating seat 16 on which a driver or a passenger sits. The front ends of the left and right body tubes 8 are joined in the vicinity of the boundary between the front inclined portion 521 and the curved portion 522 of the main tube 52 and extend substantially rearward. As shown in FIGS. 2 (a) and 2 (b), each of the left and right body tubes 8 has a joining portion 85, a first bent portion 81, a second bent portion 82, and a third bent portion in order from the front side. A bent portion 83 and a fourth bent portion 84 are formed. The joint portion 85 is a portion that is joined to the rear end portion of the front inclined portion 521 of the main tube 52 or the upper portion of the curved portion 522. The first bent portion 81 is a portion formed in the vicinity of the rear end of the joint portion 85 and is a portion bent outward in the left-right direction (= vehicle width direction). Note that the first bent portion 81 is not bent in the vertical direction. The second bent portion 82 is a portion formed at a position separated from the rear of the first bent portion 81 and is a portion bent in the vertical direction. The second bent portion 82 is not bent in the left-right direction. The third bent portion 83 is a portion formed at a position spaced rearward from the second bent portion 82, and is a portion bent in the left-right direction. However, the third bent portion 83 is not bent in the vertical direction. The fourth bent portion 84 is a portion formed at a position spaced rearward from the third bent portion 83, and is a portion bent in the vertical direction. However, the fourth bent portion 84 is not bent in the left-right direction.

Then, as shown in FIG. 2B, the angle between the joint 85 and the second bent portion 82 (including the joint 85) is the same as that of the front inclined portion 521 of the main tube 52 in a side view. With a downward slope. That is, the center line C _M of the front inclined portion 521 of the main tube 52, and the center line C _B between the joint portion 85 and the second bending portion 82 is substantially parallel in side view (see FIG. 6) . The second bent portion 82 and the fourth bent portion 84 extend substantially horizontally. A portion on the rear side of the fourth bent portion 84 is inclined rearwardly. For this reason, a portion extending substantially horizontally between the second bent portion 82 and the fourth bent portion 84 is formed at a position lower than the joint portion 85. Further, as shown in FIG. 2 (a), in the top view, the left and right body tubes 8 have a left-right distance in the portion between the first bent portion 81 and the third bent portion 83 as they move backward. The part which spreads and is behind the 3rd bending part 83 is substantially parallel. The left and right body tubes 8 are bent at a first bent portion 81 formed between the joint portion 85 and the second bent portion 82. However, the first bent portion 81 is bent in the left-right direction, but is not bent in the up-down direction. For this reason, as shown in FIG. 2B, in the side view, the portion between the joint portion 85 and the second bent portion 82 does not appear to be bent at the first bent portion 81, Looks almost straight.

  As described above, the body tube 8 includes a portion extending substantially horizontally from the second bent portion 82 toward the rear (= a portion between the second bent portion 82 and the fourth bent portion 84). , And a portion (= portion after the fourth bent portion 84) that slopes backward from the rear end of the substantially horizontally extending portion. A portion extending substantially horizontally from the second bent portion 82 toward the rear is formed at a position lower than the joint portion 85.

  In addition, a second reinforcing member 57 is provided in the vicinity of the joint portion between each of the left and right body tubes 8 and the main tube 52. The second reinforcing member 57 is a member provided for securing and improving the bonding strength between each of the left and right main tubes 52 and the main tube 52. Specifically, the second reinforcing member 57 is a plate-shaped member, and a certain one side (here, the upper side) of the first bent portion 81 and the second bent portion 82 of each of the left and right main tubes 52. The other one side (here, the lower side) is joined to the curved portion 522 of the main tube 52. Further, a front cross member 60, an intermediate cross member 61, and a rear cross member 62 are provided across the left and right body tubes 8. The front cross member 60, the intermediate cross member 61, and the rear cross member 62 have a function of securing the strength of the frame 5 by connecting the left and right body tubes 8, a function of supporting the seating seat 16, And has a function of fixing other predetermined members. For example, the front cross member 60 is a plate-like member and is provided across the first bent portion 81 and the second bent portion 82 of the left and right body tubes 8. The intermediate cross member 61 is a plate-like member and is provided across the second bent portion 82 and the third bent portion 83. The rear cross member 62 is a pipe-like member, and is provided across portions that are inclined rearwardly upward.

  The left and right side tubes 54 are members that support the left and right body tubes 8. The left and right side tubes 54 are pipe-shaped members, and are provided so as to straddle each of the left and right body tubes 8, the main tube 52, and the frame pivot 55. Specifically, as shown in FIG. 2 (b), the upper ends of the left and right side tubes 54 are joined to the rear inclined bracket 58 and the rear inclined portions of the left and right body tubes 8. On the other hand, the lower ends of the left and right side tubes 54 are joined to the rear inclined portion 523 of the main tube 52 and the frame pivot 55.

  The rear cushion bracket 58 is a bracket to which the upper end of the rear cushion unit 132 is coupled so as to be swingable. The rear cushion bracket 58 is a flat plate-like member, and is joined across a portion of each of the left and right body tubes 8 that inclines rearward and the upper end of each of the left and right side tubes 54.

  Next, the configuration of the body tube 8 of the main frame 5 and the configuration of the joint portion 85 between the body tube 8 and the main tube 52 will be described with reference to FIGS. FIG. 3 is a perspective view of the joint portion 85 between the main tube 52 and the body tube 8 as viewed obliquely from behind and above. FIG. 4 is a side view of the joint portion 85 between the main tube 52 and the body tube 8. FIG. 5A is a plan view of the joint 85 between the main tube 52 and the body tube 8 as viewed from above. FIG. 5B is a plan view of the joint 85 between the main tube 52 and the body tube 8 as viewed from below. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG.

As shown in FIGS. 3 to 7, the body tube 8 is formed by a pipe-shaped member having a hollow inside. A joint portion 85 having a predetermined length in the axial direction is formed at the front end of the body tube 8. The joint portion 85 is a portion that is overlapped and joined (here, welded) to the outer peripheral surface of the main tube 52. For this reason, the joint portion 85 is formed by crushing the front end portion of the body tube 8 in a substantially flat manner in accordance with the shape of the outer peripheral surface of the main tube 52. For example, if the main tube 52 is configured by a pipe-shaped member having a substantially circular cross section, the joint portion 85 of the body tube 8 is formed in a substantially flat cross-sectional arc shape. As a method for forming the joint portion 85, a method of flattening by pressing or the like can be applied. Then, the joint portion 85 is superimposed on the outer peripheral surface of the main tube 52, and the joint portion 85 is welded to the main tube 52 in this state. With such a structure, by increasing the dimension of the center line C _B of the joint 85, it is possible to increase the welding length of the joint portion 85 and the main tube 52. Therefore, it is easy to improve the joint strength (= weld strength) between the body tube 8 and the main tube 52. Furthermore, since the joining portion 85 and the main tube 52 can be welded in a substantially straight line, the joining work (= welding work) can be simplified. Therefore, productivity can be improved.

In particular, as shown in FIGS. 4 and 5A, a first bent portion 81 is formed in the vicinity of the rear end of the joint portion 85. The first bent portion 81 is a portion that is bent outward in the left-right direction (= vehicle width direction) (particularly, see FIG. 5A) but not bent in the vertical direction (particularly, see FIG. 4). A second bent portion 82 is formed at a position spaced rearward from the first bent portion 81. The second bent portion 82 is a portion that is bent in the vertical direction (especially, see FIG. 4) but not bent in the horizontal direction (especially, see FIG. 5A). Therefore, particularly as shown in FIGS. 4 and 6, in a side view, a center line C _B from the junction 85 over the second bend portion 82, the center line C of the front inclined portion 521 of the main tube 52 _It is almost parallel to _M and slopes downward. With such a configuration, it is possible to prevent stress from concentrating on the rear end of the joint portion 85 and in the vicinity thereof. The reason for this is as follows. Generally, stress is likely to concentrate at a location where the cross-sectional dimension of the member changes. Further, the stress in the bending direction tends to concentrate on the portion where the member is bent. Therefore, the first bent portion 81 formed at the rear end of the body tube 8 is bent only in the left-right direction (= vehicle width direction) and is not bent in the up-down direction. Changes in the size and shape of the cross section in the vicinity of the end can be moderated. For this reason, stress concentration caused by changes in the cross-sectional dimensions and shapes can be mitigated. Furthermore, it can prevent that the stress of an up-down direction concentrates on the 1st bending part 81 by setting it as the structure which is bent only in the left-right direction and is not bent in the up-down direction. Therefore, as a whole, stress can be prevented or suppressed from concentrating near the rear end of the joint portion 85. As a result, the strength required for the body tube 8 can be reduced, and the weight and structure of the body tube 8 can be simplified.

  In particular, as shown in FIGS. 4, 5 (b), and 7, between the first bent portion 81 and the second bent portion 82 of the left and right body tubes 8, and the curved portion 522 of the main tube 52. The second reinforcing member 57 is joined over the two. Specifically, the second reinforcing member 57 is a plate-like member, and one side is welded between the first bent portion 81 and the second bent portion 82 of the left and right body tubes 8, Another certain side is welded to the curved portion 522 of the main tube 52. The second reinforcing member 57 can secure and improve the bonding strength between the body tube 8 and the main tube 52. Further, a front cross member 60 is provided across the first bent portion 81 and the second bent portion 82 of the left and right body tubes 8. Specifically, the front cross member 60 is a plate-like member, and one side is welded between the first bent portion 81 and the second bent portion 82 of one body tube 8, and the other is One side is welded between the first bent portion 81 and the second bent portion 82 of the other body tube 8. The front cross member 60 has a function of securing and improving the rigidity of the main frame 5 and also functions as a bracket for attaching other predetermined members.

  In the 2nd bending part 82, it bends only in the up-down direction, and is not bent in the left-right direction. A third bent portion 83 is formed at a position spaced rearward from the second bent portion 82, and a fourth bent portion 84 is formed at a position spaced further rearward from the third bent portion 83. The The third bent portion 83 is a portion that is bent only in the left-right direction and not bent in the up-down direction. The fourth bent portion 84 is a portion bent in the vertical direction. Then, in a side view, the portion from the second bent portion 82 to the fourth bent portion 84 extends substantially horizontally. The rear side of the fourth bent portion 84 is inclined rearwardly upward. According to such a configuration, a portion between the second bent portion 82 and the fourth bent portion 84 (= portion extending substantially horizontally) is formed at a position lower than the joint portion 85. Further, in the portion from the first bent portion 81 to the third bent portion 83, the distance between the left and right body tubes 8 gradually increases toward the rear. The third bent portion 83 is bent in the left-right direction, and the left and right body tubes 8 are substantially parallel to the rear side of the third bent portion 83.

  Next, the relationship between the frame 5 and other devices and members will be described with reference to FIGS. FIG. 8 is a side view showing a state in which the engine unit 12 and the rear wheel suspension device 13 are assembled to the main frame 5. FIG. 9 is a plan view showing a state in which the engine unit 12 and the rear wheel suspension device 13 are assembled to the main frame 5. As shown in FIGS. 8 and 9, the engine unit 12 is disposed in a region surrounded by the main tube 52 and the down tube 53 of the main frame 5. Specifically, the engine unit 12 includes the upper frame 66 attached to the engine suspension tube 59, the lower bracket 65 attached to the down tube 53, and the frame pivot 55 through bolts and screws, etc. Fixed to. In an area surrounded by the body tube 8, the main tube 52, and the side tube 54, devices and members related to intake air such as the air cleaner 17 are arranged. The front end of the swing arm 131 of the rear wheel suspension device 13 is connected to the frame pivot 55 so as to be swingable in the vertical direction. Further, the upper end of the rear cushion unit 132 of the rear wheel suspension device 13 is swingably connected to the rear cushion bracket 58.

  As shown in FIGS. 8 and 9, a seating seat 16 on which a driver and a passenger can sit is provided on the upper side of the body tube 8 via a seat rail (not shown). In particular, as shown in FIG. 8, the portion 161 on which the driver sits in the seat 16 is between the second bent portion 82 and the fourth bent portion 84 of the body tube 8 (= from the second bent portion 82). It is located on the upper side of the portion extending substantially horizontally toward the rear. In other words, the portion 161 on which the driver sits in the seating seat 16 is located above the portion provided at a position lower than the joint portion 85 of the body tube 8. According to such a configuration, the portion 161 on which the driver is seated in the seating seat 16 can be lowered, so that the driver can easily put his feet on the ground. Therefore, the operability and ride comfort of the motorcycle 1 can be improved.

  The actions and effects of the main frame 5 and the main motorcycle 1 are summarized as follows.

  The body tube 8 of the frame 5 is bent only in the left-right direction (= vehicle width direction) at the rear end of the joint portion 85 and in the vicinity thereof, and is not bent in the up-down direction. For this reason, changes in cross-sectional dimensions and shapes can be moderated at the rear end of the joint portion 85 and in the vicinity thereof. In general, stress tends to concentrate at locations where the cross-sectional dimensions and shape change rapidly. Since the body tube 8 of the present frame 5 has a gradual change in cross-sectional dimension and shape at the rear end of the joint portion 85 and in the vicinity thereof, stress concentration is prevented or suppressed. Furthermore, since the rear end of the joint portion 85 and the vicinity thereof are not bent in the vertical direction, even when the vertical load is applied to the body tube 8, the vertical stress is concentrated on the portion. Can be prevented or suppressed. Thus, according to this frame 5, it can prevent or suppress that stress concentrates on the rear end of junction part 85 of body tube 8, and its neighborhood. Accordingly, the strength required for the body tube 8 can be reduced, and the weight of the main frame 5 can be reduced and the structure can be simplified.

The joint portion 85 of the body tube 8 of the frame 5 is formed by squashing a pipe-like member. With such a configuration, the joining portion 85 can be easily formed by press working or the like. On the other hand, for example, in a configuration in which the body tube 8 is butted against the main tube 52 and welded, the end of the body tube 8 needs to be processed according to the size and shape of the outer peripheral surface of the main tube 52. For this reason, labor is required for processing. In the main frame 5, the formation of the joining portion 85 is easy, so that the productivity of the main frame 5 can be improved. Furthermore, the welding length between the body tube 8 and the main tube 52 can be easily increased by increasing the axial length of the joint portion 85. For this reason, it is easy to improve the joining strength as compared with the configuration in which the body tube 8 is butted against the main tube 52 and welded. Furthermore, since it is possible to linearly welded along the direction of the center line C _B of the joint 85, it can be simplified welding operation. Therefore, productivity can be improved.

  The body tube 8 of the main frame 5 is not bent in the vertical direction at the rear end of the joint portion 85, and is tilted rearward as it is, and the height thereof becomes lower toward the rear side. And the height of the part extended substantially horizontally can be provided in the position lower than the junction part 85. FIG. Therefore, the height of the seating seat 16 (strictly, the height of the portion 161 on which the driver sits in the seating seat 16) is lowered without lowering (or increasing) the height of the main tube 52. can do. Because the height of the front inclined portion 521 of the main tube 52 does not decrease (or increases), the size of the region where the engine unit 12 is disposed does not decrease (or increases). For this reason, the degree of freedom of layout of the engine unit 12 and other predetermined devices does not decrease (or the degree of freedom can be improved). Further, it is possible to prevent the engine unit 12 and other predetermined devices from being attached, and the workability of the attached engine unit 12 and other predetermined devices from being deteriorated (or workability can be improved). . Since the seating seat 16 can be lowered, the driver can easily put his feet on the ground. For this reason, the operability and riding comfort of the motorcycle 1 can be improved. As described above, the main frame 5 can achieve both maintenance or improvement of the degree of freedom of layout of the engine unit 12 or the like, maintenance or improvement of workability, and improvement of operability and riding comfort.

In addition, as a structure which makes the body tube 8 low, making the main tube 52 low, for example, the junction location of the body tube 8 and the main tube 52 is made into the rear end side (= lower end side) of the main tube 52. A configuration of moving to a lower position is conceivable. However, such a configuration has the following problems. The main tube 52 is inclined more toward the rear end side. Therefore, when moving the joint between the body tube 8 and the main tube 52 at the rear end of the main tube 52, the center line C _M of the center line C _B and the main tube 52 of the body tube 8 in the joint forms The angle increases. For this reason, the body tube 8 needs to be bent greatly in the vertical direction at the rear end of the joint portion 85 and in the vicinity thereof. If it does so, it will become easy to concentrate the stress of an up-down direction in the rear end of the junction part 85 of the body tube 8, and its vicinity. As a result, it is necessary to improve the strength of this portion, and the body tube 8 and the joint portion between the body tube 8 and the main tube 52 are increased in size or complicated in structure. On the other hand, in the present frame 5, the joint portion between the body tube 8 and the main tube 52 is provided at the rear end portion of the front inclined portion 521 of the main tube 52 or the upper portion of the curved portion 522. For this reason, it is not necessary to bend the rear end of the joint portion 85 of the body tube 8 and the vicinity thereof in the vertical direction. In other words, the body tube 8 branches gently from the main tube 52. Therefore, it is possible to prevent stress in the vertical direction from concentrating on the joint 85 and its vicinity.

  As mentioned above, although embodiment (Example) of this invention was described in detail, the said embodiment (Example) only showed the specific example in implementing this invention. The technical scope of the present invention is not limited to the above-described embodiment (example). The present invention can be variously modified without departing from the spirit thereof, and these are also included in the technical scope of the present invention.

  In the embodiment, the main tube 52 and the body tube 8 are configured by pipe-shaped members having a substantially circular cross section. However, the cross sectional shapes of the main tube 52 and the body tube 8 are limited to a substantially circular shape. is not. The cross-sectional shapes of the main tube 52 and the body tube 8 may be, for example, an ellipse or a polygon such as a quadrangle. The point is that the joining portion 85 of the body tube 8 may be configured to be superposed on the outer peripheral surface of the main tube 52. For example, if the main tube 52 is composed of a member having a quadrangular cross section, the joint portion 85 of the body tube 8 can be configured to be crushed into a substantially straight cross section or a substantially “L” cross section.

  Moreover, in the said embodiment, although the main tube 52 showed the structure which is one pipe-shaped member which passes along the center of the left-right direction (= vehicle width direction) of this motorcycle 1, this invention shows such a structure. It is not limited to the configuration. For example, the present invention can also be applied to a motorcycle including a pair of left and right main tubes 52 substantially parallel to each other. In this case, a configuration in which the left and right body tubes 8 are joined to the left and right main tubes 52 can be applied. The left and right body tubes 8 may be configured to branch inward from the left and right main tubes 52, respectively, or may be configured to branch outward.

  The present invention can be applied to a motorcycle frame and a motorcycle. And according to this invention, it can prevent or suppress that stress concentrates by making a change of a cross-sectional dimension and a shape moderate in the rear end of a junction part, and its vicinity. In addition, since the rear end of the joint and its vicinity are not bent in the vertical direction, even when a vertical load is applied to the body tube, the stress in the vertical direction is prevented from concentrating on that part. it can. In this way, stress can be prevented from concentrating on the rear end of the joint portion of the body tube and in the vicinity thereof.

1: a motorcycle according to an embodiment of the present invention, 5: a frame according to an embodiment of the present invention, 15: a fuel tank, 8: a body tube, 16: a seating seat, 161: a portion of the seating seat where the driver is seated, 51: head pipe, 52: main tube, 81: first bend of body tube, 82: second bend of body tube, 83: third bend of body tube, 84: fourth bend of body tube 85: Body tube joint, 521: Main tube front inclined portion, 522: Main tube curved portion, C _M : Center line of main tube front inclined portion, C _B : Body tube joint portion Center line in side view of the part from the first to the second bend

Claims (7)

A main tube formed with a front inclined portion that is inclined to extend rearwardly downward and a curved portion that curves from the rear end of the front inclined portion and curves substantially downward;
A joint portion joined to the rear end portion or the upper portion of the curved portion of the front inclined portion of the main tube, and a first bent portion that is bent in the vehicle width direction and not in the vertical direction in the vicinity of the rear end of the joint portion. And a second bent portion bent in the vertical direction at a position spaced rearward from the first bent portion, and a center line between the joint portion and the second bent portion in a side view A body tube substantially parallel to the center line of the front inclined portion of the main tube;
A motorcycle frame characterized by comprising:   2. The motorcycle frame according to claim 1, wherein the joint portion of the body tube is formed of a pipe-like member and is crushed substantially flat. 3.   The body tube is formed with a portion that extends substantially rearward from the second bent portion and supports a seating seat on which a driver can sit, and the portion that supports the seating seat is lower than the joint portion. The motorcycle frame according to claim 1, further comprising a portion formed at a position.   The body tube has a portion extending substantially horizontally from the second bent portion substantially rearwardly, and a portion inclined rearward from a rear end of the substantially horizontally extending portion. 3. The motorcycle frame according to claim 1, wherein a portion extending in a vertical direction is formed at a position lower than the joint portion.   A motorcycle comprising the frame of the motorcycle according to any one of claims 1 to 4. A motorcycle frame according to claim 3;
A seat on which the driver is seated;
With
The part of the seating seat on which the driver is seated is located above the part of the body tube that is formed at a position lower than the joint part. A motorcycle frame according to claim 4;
A seat on which the driver is seated;
With
The portion of the seating seat on which the driver is seated is located above the portion that extends substantially horizontally from the second bent portion toward the rear.

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