JP6206344B2 - Motorcycle frame structure - Google Patents

Description

  The present invention relates to a frame structure of a motorcycle, and more particularly, to a frame structure of a cradle type motorcycle in which pipes are arranged vertically so as to surround an engine.

  In general, a motorcycle is provided with a body frame constituting a framework, and the body frame has a function of supporting main components such as an engine and a suspension.

  There are several different types of body frame structures. For example, a cradle type structure in which pipes, tubes and the like are arranged so as to surround the engine is known.

  As a conventional cradle type frame structure, there are a semi-double cradle type as described in Patent Document 1, a single cradle type as described in Patent Document 2, and the like.

  The frame structure of the semi-double cradle type of Patent Document 1 has a down tube that extends from the head pipe to the rear through the front and the bottom of the engine, and branches to the left and right from the center tube and the lower end of the center tube. And two side tubes joined to each other. And the rear-end part of each side tube is welded and joined to the lower cross pipe constructed by the lower end of a right-and-left rear arm bracket.

  On the other hand, in the frame structure of the single cradle type of Patent Document 2, one pipe extends from the head pipe to the rear through the front and the lower part of the engine, and the rear end of this pipe is formed at the lower part of the center pipe. It is welded. And the joining location of this pipe and a center pipe is reinforced by welding a reinforcing member.

JP-A-5-178254 JP-A-10-86875

  However, in the above-described conventional semi-double cradle type frame structure, the down tube is composed of one center tube and two side tubes joined so as to branch left and right from the lower end of the center tube. The left and right side tubes are arranged to expand in the vehicle body width direction below the engine. For this reason, there is a problem that layout restrictions are imposed on components such as exhaust pipes arranged around the side tube, and the arrangement and structure of the components must be changed.

  On the other hand, in the conventional single cradle type frame structure described above, the rear end portion of one pipe extending from the head pipe to the rear through the front and the lower side of the engine is welded and joined to the lower portion of the center pipe. The joint portion is reinforced by a reinforcing member. Therefore, it takes time to join both pipes, and there is a problem that the strength of the joining portion cannot be sufficiently increased for the troublesome work.

  Conventionally, in order to park the motorcycle with the rear wheel floating, when the center stand is provided, the center stand is generally supported near the joint of both pipes. In the type of frame structure, there is a problem that it is necessary to change the conventional center stand mounting method or the center stand structure itself.

  The present invention has been made to solve the above-described problems, and does not require layout restrictions on components such as an exhaust pipe and a center stand, and does not require a change in the arrangement or structure of the components. An object of the present invention is to provide a frame structure.

  In order to achieve the above object, the present invention includes a head pipe provided at a front portion of a vehicle body frame, a tank rail formed to be inclined rearward and downward from the head pipe, and a lower portion extending from the rear portion of the tank rail. A left and right body frame, a bridge tube installed at a lower portion of the left and right body frames, and a single down tube extending from the head pipe to the rear through the front and the bottom of the engine. A motorcycle frame structure provided with a rear end portion of the down tube located obliquely below and forward of the bridge tube, and the rear end portion of the down tube and the bridge tube are connected via a connecting member. It is characterized by.

  According to this configuration, since the down tube extending forward and downward of the engine is constituted by a single tube, layout restrictions are imposed on engine peripheral components arranged around the down tube. Absent. Therefore, the components can be easily and compactly arranged without the need for such arrangement of components and change of structure. Moreover, by joining one down tube and a bridge tube via a connection member, it is possible to simplify the joining operation and provide a frame structure with sufficient strength.

  In the frame structure of the motorcycle according to the present invention, the connecting member is formed in a bifurcated shape having inclined portions that expand from the rear end portion of the down tube toward the left and right sides toward the bridge tube. Is preferred.

  According to this configuration, the connecting member can be easily formed, and the connecting member can have sufficient strength. In addition, when the center stand is provided, the center stand stopper portion can be arranged inside the left and right joints with the bridge tube of the connecting member, so that the space can be used effectively and the size can be reduced. it can.

  In the frame structure of the motorcycle according to the present invention, it is preferable that the central axis of the connecting member coincides with the central axis of the bridge tube.

  According to this configuration, when the connecting member is attached to the bridge tube, the directionality of the assembly is lost, so that the assembly in the wrong direction can be prevented and the efficiency of the joining operation can be increased.

  Further, in the motorcycle frame structure according to the present invention, the joint portion between the rear end portion of the down tube and the connection member extends in the front-rear direction and extends rearwardly under the engine. It is preferable to be located between the bridge tube and the chamber for accommodating the catalyst body disposed in the middle of the tube.

  According to this configuration, since the catalyst body is accommodated and the chamber formed in a large diameter is arranged in front of the connection member, the exhaust pipe can be passed more inside the vehicle body, ensuring the bank angle and The appearance can be improved.

  In the frame structure of the motorcycle according to the present invention, it is preferable that the exhaust pipe is disposed so as to overlap an inclined portion of the connection member in a vehicle body plan view and a vehicle body side view.

  According to this configuration, since the exhaust pipe can be disposed in the vicinity of the inclined portion, the ground height of the exhaust pipe can be sufficiently ensured, and the bank angle and the appearance can be further improved. .

  In the frame structure of the motorcycle according to the present invention, left and right center stand brackets that rotatably support a center stand are fixed to the bridge tube, and the center stand has a stand stopper portion attached to the bridge tube. The center stand bracket and the stand stopper portion are disposed inside the left and right joints between the connection member and the bridge tube in the left-right direction. Is preferred.

  According to this configuration, it is possible to easily attach the center stand having the same structure as the conventional one without changing the attachment method.

  According to the present invention, various excellent features such as no layout restrictions on components such as exhaust pipes and center stands arranged around the engine, and no change in the arrangement or structure of the components are required. Effects can be obtained.

1 is a side view showing a frame structure of a motorcycle according to an embodiment of the present invention. 1 is a front view showing a frame structure of a motorcycle according to an embodiment of the present invention. 1 is a perspective view showing a frame structure of a motorcycle according to an embodiment of the present invention. 1 is a bottom view showing a frame structure of a motorcycle according to an embodiment of the present invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a bottom view showing a center stand in a frame structure of a motorcycle according to an embodiment of the present invention.

  Hereinafter, a frame structure of a motorcycle according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the directions of the front, rear, left and right are based on the direction viewed from the rider riding the motorcycle.

  As shown in FIG. 1, the motorcycle is provided with a body frame 10 made of steel or aluminum alloy which constitutes the framework of the body. The vehicle body frame 10 has a cradle type frame structure in which pipes, tubes and the like are arranged so as to surround the engine 11.

  As shown in FIGS. 1 to 3, the vehicle body frame 10 includes a head pipe 12 provided at a front portion, a tank rail 13 formed to be inclined rearward and downward from the head pipe 12, and the tank rail 12. The left and right body frames 14L, 14R branching left and right from the rear and extending downward, the down tube 15 extending rearward from the head pipe 12 through the front and the lower side of the engine 11, and each body frame 14L Left and right seat rails 16L, 16R extending rearward from the upper part of each of 14R, and left and right bridges in an inclined posture between the rear part of each of the seat rails 16L, 16R and the lower part of each of the body frames 14L, 14R. Cross frames 17L, 17R.

  The head pipe 12 is composed of a pipe material having a circular cross section, and is formed in a straight line with a downwardly inclined posture. Although not particularly shown, the head pipe 12 is provided with a front fork pivotally supporting the front wheel at the lower end and a steering shaft with a handle bar provided at the upper end. The front wheel is rotated left and right by steering.

  The tank rail 13 is composed of a pipe material having a circular cross section, and is formed in a straight line with a downwardly inclined posture. The front end portion of the head pipe 12 and the tank rail 13 and the upper end portion of the down tube 15 are fixed to each other by a substantially triangular reinforcing gusset 19. A rubber tank support or the like (not shown) is provided on the upper surface of the tank rail 13, and a fuel tank (not shown) is supported on the tank rail via the tank support or the like. An engine suspension plate 20 that suspends the upper portion of the engine 11 is attached to the lower surface of the tank rail 13. Further, at the rear end portion of the tank rail 13, a joint portion 21 to be joined to the upper end portions of the left and right body frames 14L and 14R is provided.

  Pivot brackets 22L and 22R are respectively attached to the lower sides of the left and right body frames 14L and 14R, and swing arms (not shown) are swingably supported by the pivot brackets 22L and 22R. Further, support arms 23L and 23R are respectively attached to the lower portions of the left and right body frames 14L and 14R toward the front, and a footrest (not shown) is supported via the support arms 23L and 23R.

  A connecting rod 24 is laid across the left and right body frames 14L and 14R so as to connect the left and right body frames 14L and 14R to each other at substantially the center in the vertical direction. Also, brackets 25 are attached to the left and right body frames 14L, 14R in the vicinity of the connecting rod 24 and obliquely upward and rearward. Furthermore, a bridge tube 26 is horizontally mounted on the lower ends of the left and right body frames 14L and 14R.

  As shown in FIGS. 4 to 7, the bridge tube 26 is made of a pipe material having a circular cross section, and is formed linearly in the vehicle body width direction (left-right direction). Engine suspension plates 27L and 27R are attached to the circumferential wall surface of the bridge tube 26 diagonally forward and upward, respectively, at symmetrical positions with respect to the vehicle body center line CL (see FIG. 7). In addition, a pair of left and right center stand brackets 18L and 18R protrudes rearward from the peripheral wall surface of the bridge tube 26 at a predetermined interval in the vehicle body width direction (left and right direction). Further, a hook portion 28 curved in a U shape is attached to the rear wall surface of the bridge tube 26 on the left outer side of the left center stand bracket 18L.

  Referring to FIGS. 1 to 3 again, the down tube 15 is composed of a single pipe member having a circular cross section. The down tube 15 is curved forward and downward from the lower end of the engine front portion 29 and extends horizontally rearward below the engine 11 and extends forward and obliquely downward from the head pipe 12 in front of the engine 11. And an engine lower portion 30.

  The rear end portion of the down tube 15 and the bridge tube 26 are connected via a connection member 31. The connecting member 31 is bifurcated so as to extend from the left and right ends of the welded portion 32 to the left and right sides of the welded portion 32 obliquely upward and rearward. The rear end portion of the down tube 15 is welded to the center portion of the welded portion 32. The inclined portions 33L and 33R are formed.

  As shown well in FIG. 5, the left and right inclined portions 33 </ b> L and 33 </ b> R are welded to the bridge tube 26 so that the center axis CA <b> 1 coincides with the center axis CA <b> 2 of the bridge tube 26. As well shown in FIG. 7, the joint portions of the left and right inclined portions 33L and 33R with respect to the bridge tube 26 are respectively formed from the pair of left and right center stand brackets 18L and 18R and the left and right engine suspension plates 27L and 27R. It is located outside in the width direction.

  As shown in FIG. 1, the engine 11 is disposed in a space surrounded by the tank rail 13, the body frames 14 </ b> L and 14 </ b> R, the down tube 15, and the connection member 31 having such a configuration. Yes. The engine 11 is, for example, a four-cycle single cylinder type engine, and is fixed to the engine suspension plates 20, 27L, 27R by bolting. The engine 11 includes a crankcase 34 that houses a crankshaft (not shown) that extends in the vehicle body width direction (left-right direction), and a cylinder block 35 and a cylinder that are arranged in an inclined posture in the obliquely upper front direction of the crankcase 34 from the bottom. The head 36 and a cylinder head cover 37 provided so as to cover the cylinder head 36 from above are provided.

  An exhaust pipe 38 is connected to an exhaust port disposed on the front side surface of the cylinder head 36. The exhaust pipe 38 hangs down from the front of the engine 11 and extends further to the rear below the engine 11 and through the right side of the down tube 15, and is located on the right side of the connection member 31 in the vehicle body plan view and the vehicle body side view. It overlaps with the inclined portion 33R (see FIG. 4).

  As shown in FIG. 4, a chamber 39 for accommodating a catalyst body for purifying exhaust of the engine 11 is interposed in the middle of the exhaust pipe 38. The chamber 39 is formed to have a larger diameter than the front and rear exhaust pipe portions, and is positioned in front of the joint portion between the rear end portion of the down tube 15 and the welded portion 32 of the connecting member 31. A muffler 40 is provided at the rear end of the exhaust pipe 38.

  Referring again to FIG. 1 to FIG. 3, the connecting rods 41 and 42 are laterally connected to the front and rear ends of the left and right seat rails 16L and 16R so as to connect the left and right seat rails 16L and 16R to each other. It is built. Seats (not shown) are supported on the left and right seat rails 16L and 16R.

  Brackets 43 are respectively attached to the left and right cross frames 17L and 17R obliquely upward and forward. Between the lower portions of the left and right cross frames 17L and 17R and the lower portions of the left and right body frames 14L and 14R, guide frames 44L and 44R extending in a substantially V shape toward the rear are respectively constructed. Pillion step guide plates 45L and 45R are supported at the rear ends of 44L and 44R, respectively.

  An air cleaner (not shown) is disposed in a triangular space in a side view surrounded by the body frames 14L and 14R, the seat rails 16L and 16R, and the cross frames 17L and 17R. Between the upper ends of the left and right body frames 14L, 14R and the front ends of the left and right seat rails 16L, 16R, between the left and right seat rails 16L, 16R and the left and right cross frames 17L, 17R, and the left and right bodies Reinforcing plates 46, 47, and 48 are respectively installed between the lower ends of the frames 14L and 14R and the lower ends of the left and right cross frames 17L and 17R.

  As shown in FIGS. 4, 5 and 7, a center stand 50 is provided in the vicinity of the lower center of the body frame 10. The center stand 50 includes a stand rotating shaft 51 installed between a pair of left and right center stand brackets 18L and 18R joined to the bridge tube 26, a pivot pipe 52 supported by the stand rotating shaft 51, and a pivot pipe. Stand levers 53L and 53R that extend in a U-shape from 52 and are provided integrally with the left and right sides. The stand levers 53L, 53R are located between a parking position (see FIG. 5) where the free ends 54L, 54R are lowered and a travel position (see FIG. 7) where the free ends 54L, 54R are flipped up backward. Thus, it can freely rotate around the stand rotation shaft 51.

  A plate-like stand stopper portion 54 having a length that fits between the left and right center stand brackets 18L and 18R is fixed to the vicinity of the pivot pipe 52 of the stand levers 53L and 53R. When the stand levers 53L and 53R rotate to the parking position, the stand stopper portion 54 contacts the bridge tube 26 on the inner side of the left and right joints between the left and right inclined portions 33L and 33R of the connection member 31 and the bridge tube 26. By contacting, the forward rotation of the stand levers 53L and 53R from the parking position is restricted.

  A latching portion 55 is attached to the outside of the central portion of the left stand lever 53L, and a coil spring 56 is interposed between the latching portion 55 and the hook portion 28 of the bridge tube 26. Due to the biasing force of the coil spring 56, the stand levers 53L and 53R are positioned with good stability at the parking position or the traveling position.

  As described above, according to the frame structure of the motorcycle according to the above-described embodiment, the down tube 15 extending forward and downward of the engine 11 is constituted by a single tube. There are no layout restrictions on the peripheral components of the engine 11 such as the exhaust pipe 38 and the center stand 50 arranged at the center. Therefore, the components can be easily and compactly arranged without the need for such arrangement of components and change of structure. Further, by connecting the single down tube 15 and the bridge tube 26 via the connecting member 31, it is possible to simplify the joining operation and provide a frame structure with sufficient strength.

  Further, the connection member 31 can be easily formed by forming the connection member 31 in a bifurcated shape extending from the rear end portion of the down tube 15 toward the left and right sides toward the bridge tube 26, and the connection member 31. Can have sufficient strength. Further, when the center stand 50 is provided, the center stand stopper portion 54 can be disposed inside the left and right joint portions of the connecting member 31 with the bridge tube 26, so that the space can be used effectively and the size can be reduced. Can be achieved.

  In addition, by making the central axis of the connecting member 31 coincide with the central axis of the bridge tube 26, when the connecting member 31 is attached to the bridge tube 26, the directionality of the assembly is lost, so that the wrong direction is prevented from being assembled. This can increase the efficiency of the joining operation.

  Further, since the catalyst body is accommodated, the chamber 39 formed with a large diameter is disposed in front of the connection member 31, and the exhaust pipe 38 is disposed so as to overlap the inclined portions 33L and 33R, thereby further increasing the inside of the vehicle body. The exhaust pipe can be allowed to pass through, the ground height of the exhaust pipe can be sufficiently secured, and the bank angle can be secured and the appearance can be improved.

  Further, the left and right center stand brackets 18L and 18R are fixed to the bridge tube 26, and the center stand brackets 18L and 18R and the stand stopper portion 54 are arranged inside the left and right joints between the connecting member 31 and the bridge tube 26. Thus, the center stand 50 having the same structure as the conventional one can be easily attached without changing the attachment method.

  In addition, since description of embodiment of this invention mentioned above has demonstrated the preferred embodiment in the frame structure of the motorcycle which concerns on this invention, it may attach | subject the technically preferable various restrictions. However, the technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

DESCRIPTION OF SYMBOLS 10 Body frame 11 Engine 12 Head pipe 13 Tank rail 14L, 14R Body frame 15 Down tube 18L, 18R Center stand bracket 26 Bridge tube 31 Connection member 33L, 33R Inclined part 38 Exhaust pipe 39 Chamber 50 Center stand 54 Stand stopper part

Claims (4)

A head pipe provided at a front portion of the vehicle body frame, a tank rail formed to be inclined rearward and downward from the head pipe, left and right body frames extending downward from a rear portion of the tank rail, and A motorcycle frame structure comprising: a bridge tube erected at a lower portion of a body frame; and a single down tube extending rearward from the head pipe through the front and lower sides of the engine,
The rear end portion of the down tube is located obliquely below the front of the bridge tube, and the rear end portion of the down tube and the bridge tube are connected via a connecting member ,
The frame structure of a motorcycle according to claim 1, wherein the connecting member is formed in a bifurcated shape having inclined portions that extend from the rear end portion of the down tube toward the left and right sides toward the bridge tube . A joint portion between the rear end portion of the down tube and the connection member accommodates a catalyst body disposed in the middle of an exhaust pipe extending in the front-rear direction and passing rearward of the engine toward the rear. The motorcycle frame structure according to claim 1 , wherein the frame structure is located between a chamber and the bridge tube. The motorcycle frame structure according to claim 2 , wherein the exhaust pipe is disposed so as to overlap with an inclined portion of the connection member in a plan view of the vehicle body and a side view of the vehicle body. Left and right center stand brackets that rotatably support the center stand are fixed to the bridge tube, and the center stand is provided so that a stand stopper is in contact with the bridge tube and is held at the parking position. is, the center stand bracket and the stand stopper portion is in the horizontal direction, any one of the preceding claims, characterized in that it is arranged on the inner side of the joint of the left and right of the connecting member and the bridge tube A frame structure for a motorcycle according to claim 1.

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