JP2010083380A - Vehicle body frame structure of motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance rigidity in braking even when the main frame of a front part vehicle body frame is made to be a simple structure by being divided into right and left parts and fastening with a bolt in a frame type using an engine as a part of the vehicle body frame. <P>SOLUTION: The front part vehicle body frame 2 includes a head pipe 14 and the main frame 15. The main frame 15 is made to be a right and left divided structure, and the head pipe 14 is held between them and fastened with the bolt. Attaching arms 16, 17 formed on the rear of the main frame 15 are fastened with a bolt to both right and left surfaces in a crank case 18 of the engine 3. A rear open part 55 having a large opening area is provided above the main frame 15, and a front open part 56 having a small opening area is provided below. Thereby, the lower part side of the main frame 15 is allowed to have a high rigidity to withstand a compressive load in braking. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a body frame structure of a motorcycle using an engine as a part of a body frame.
In the present application, front / rear, left / right, and up / down are based on the state of use of the motorcycle, respectively. To do.

2. Description of the Related Art A body frame structure of a motorcycle using an engine as a part of a body frame is well known. For example, a front body frame integrally casting a head pipe and a main frame extending from the rear of the vehicle body is used. There is one that uses the engine as a part of a vehicle body frame by attaching the rear part to the front part of the engine (see Patent Document 1).
Japanese Utility Model Laid-Open No. 1-170090

By the way, as in the above-described prior art, the one in which the front body frame is integrally cast becomes a large part, so that the mold for casting is also increased in size and becomes expensive.
Moreover, since it is integrally cast, the entire front body frame is also replaced when it is desired to replace a part of the front body frame.
Furthermore, when the engine is used as a part of the body frame, the main frame of the front body frame is inclined downward toward the front of the crankcase of the engine and extends rearward, so that the center of gravity of the vehicle body is increased by a brake operation or the like. When the vehicle moves forward, a large load may be applied to the lower side of the front body frame, so that it is required to increase the rigidity of the lower side of the front body frame.
This application considers such a situation.

In order to solve the above-mentioned problem, the invention according to claim 1 of the body frame structure of a motorcycle forms a front body frame by a head pipe and a main frame extending from the head pipe toward the crankcase of the engine. In the body frame structure of a motorcycle in which the rear end portion of the main frame is attached to the front portion of the engine and the engine is used as a part of the body frame,
The main frame includes a left main frame portion and a right main frame portion that are formed separately on the left and right sides and are combined and integrated with each other.
These left main frame part and right main frame part are provided with a lower edge abutting surface facing each lower part,
While constituting the main frame by bringing these lower edge abutment surfaces into contact with each other and combining them,
Each of the lower edge contact surfaces extends from the rear of the head pipe to below the upper end of the engine.

  According to a second aspect of the present invention, in the first aspect, the left main frame portion and the right main frame portion are provided with upper edge abutting surfaces facing the upper portions of the left main frame portion and the right main frame portion. It is characterized by being joined in contact.

  According to a third aspect of the present invention, in the second aspect of the invention, the main frame has an expanded portion that branches and expands left and right so that the rear portion overlaps the left and right side surfaces of the engine. Each of the rear ends is fastened to the crankcase.

According to a fourth aspect of the present invention, in the third aspect of the invention, the left and right widened portions form a rear open portion that is opened rearwardly of the upper edge contact surface on the rear upper side of the main frame and opens in the vehicle front-rear direction. And
Forming a front opening part opened in the vehicle front-rear direction behind the lower edge contact surface on the lower rear side of the main frame,
The opening area of the front opening part is smaller than the opening area of the rear opening part.

  According to a fifth aspect of the present invention, in the above-mentioned fourth aspect, the rear opening portion is opened from a fastening portion between the crankcase and the main frame to above the cylinder head portion.

According to a sixth aspect of the present invention, in the third aspect, the main frame is fastened to a cylinder portion in addition to the crankcase, and the front end of the seat rail is fastened and supported together at a fastening portion with the cylinder portion. And

According to the first aspect of the present invention, the main frame is composed of the left main frame portion and the right main frame portion which are separately provided on the left and right sides, and the left main frame portion and the right main frame portion are combined to constitute the main frame. The individual parts become smaller and the mold can be made smaller even when cast. Further, when replacement is required for each part, only that part needs to be replaced.
Further, the lower edges of the left main frame part and the right main frame part have lower edge contact surfaces that contact each other, and the contact surfaces of the lower edges are paired with a pair of left and right frames. It plays the same role as the cross pipe that connects the two, and the rigidity of the front body frame can be improved.
Furthermore, since the lower edge contact surface is below the upper end of the engine from the rear of the head pipe, the part that functions as a cross pipe becomes larger, and the rigidity of the front body frame can be further improved. Even when a heavy load is applied to the lower edge side of the front body frame by a brake operation or the like, the force can be sufficiently received.

According to the invention of claim 2, since the left main frame portion and the upper edge of the right main frame portion are in contact with each other and joined, the contact portion of the upper edge has the same function as the cross pipe connecting the pair of left and right frames. And the rigidity of the front body frame can be further improved in cooperation with the contact portion of the lower edge.

According to the invention of claim 3, since it is configured as described above, the main frame can be fastened to the crankcase having high rigidity while obtaining the effects of claims 1 and 2.

According to the invention of claim 4, a large compression force is applied to the lower edge of the main frame (the lower edge of the left main frame part and the right main frame part) by a brake operation or the like. Since the area is smaller than the opening area of the rear open part, it can be larger than the upper edge of the main frame abutting allowance of the lower edge of the main frame (the lower edge of the left main frame part and the right main frame part) The rigidity of can be improved. Moreover, since the expansion part in which the cylinder part is arrange | positioned has the front and back release part opened toward the vehicle front-back direction, a driving | running | working wind can be applied to the cylinder part of an engine.

According to the invention of claim 5, since the rear opening part is opened over the cylinder part, it is easy to perform maintenance of the cylinder part.

According to the sixth aspect of the present invention, the front end of the seat rail is supported together with the rear surface of the cylinder portion in the portion where the main frame and the engine are fastened, so that the seat rail is separately supported on the engine. There is no need to provide a boss. Moreover, the number of parts can be reduced by sharing the bolt used for fastening with the bolt for fastening the engine and the main frame. Further, since the engine and the main frame are fastened at a plurality of locations (crankcase and cylinder portion), it is possible to avoid load concentration on the crankcase.

An embodiment will be described below with reference to the drawings. FIG. 1 is a left side view of a motorcycle according to this embodiment, and FIG. 2 is an enlarged view of a part of the front side of the vehicle body.
In FIG. 1, the motorcycle includes a front wheel 1, a front body frame 2, an engine 3, a fuel tank 4, a rear body frame 5, a seat 6, a rear swing arm 7, and a rear wheel 8. Reference numeral 9 denotes a vehicle body cover.

  The front wheel 1 is supported by the lower ends of a pair of left and right front forks 10 and is steered by a handle 12 via a steering shaft 11 to which the upper ends of the front forks 10 are attached. The steering shaft 11 is connected to the front fork 10 via a bridge 13 and is rotatably supported by a head pipe 14 provided at the front end portion of the front body frame 2.

  The front body frame 2 is formed by integrally connecting a head pipe 14 and a main frame 15 extending obliquely downward from the head pipe 14 by fastening. The front portion of the main frame is connected to the head pipe 14. As will be described later, the rear part expands in a bifurcated manner and overlaps the left and right side surfaces of the engine 3. Further, when viewed from the side of the rear part, the mounting arm parts 16 and 17 are divided into front and rear parts and are bolted to the engine 3 respectively.

  The engine 3 is an air-cooled four-cycle type, and is provided with a cylinder portion 19 projecting upward from the front portion of the crankcase 18 with a slight forward inclination. The rear end of the main frame 15 covers the left and right sides of the cylinder portion 19. A carburetor 20 is located behind the cylinder part 19 to supply a mixture of the fuel in the fuel tank 4 and the clean air of the air cleaner 29 to the cylinder part 19. An exhaust pipe 21 is provided at the front part of the cylinder part 19. Connect and exhaust to the rear of the car.

  The rear body frame 5 includes a seat rail 22 whose front end is fastened to the mounting arm portion 16 and the cylinder portion 19 of the main frame 15 and extends obliquely upward and rearward, and sub-frames 23 and 24 that are V-shaped in a side view. The upper ends of the sub-frames 23 and 24 are connected to the seat rail 22, and the lower ends are integrated with a bracket 26 and bolted to the upper rear portion of the crankcase 18.

  The rear swing arm 7 is supported at a rear end portion of the crankcase 18 by a pivot shaft 25 penetrating and supported in the left-right direction so as to be swingable, and a rear wheel 8 is rotatably supported at the rear end portion. A rear cushion unit 28 is provided between the stay 27 a provided on the gusset 27 that reinforces the connection between the seat rail 22 and the subframe 24 and the rear end of the rear swing arm 7.

  This vehicle body structure is constructed by attaching the front vehicle body frame 2 to the front portion of the engine 3, attaching the rear vehicle body frame 5 to the engine 3, and further attaching the rear swing arm 7 to the crankcase 18 directly with the pivot shaft 25. 3 is used as a part of the vehicle body frame, and the front vehicle body frame 2, the engine 3 and the rear vehicle body frame 5 substantially form a highly rigid vehicle body frame.

  As shown in FIG. 2, the cylinder portion 19 is a cylinder block 30, a cylinder head 31, and a head cover 32 that are stacked and joined together with bolts and fixed to the front portion of the crankcase 18. It is a rigid structure.

An intake port (not shown) is provided on the back surface of the cylinder head 31, and the carburetor 20 is connected thereto. However, it is possible to arbitrarily connect an electronic fuel injection device instead of the vaporizer 10. An exhaust port (described later) is provided on the front surface of the cylinder head 31, and an exhaust pipe 21 is connected to the exhaust port.
A boss 33 is provided on the back surface of the cylinder head 31, and an upper portion of the mounting arm portion 16 and a front end portion of the seat rail 22 are fastened together.

  As will be described later, the main frame 15 is formed by splitting the left and right parts and fastening them with bolts and nuts, and the front part is a head pipe support that expands in a bifurcated shape toward the front. Part 34 is formed. Boss portions 35 protruding forward are provided above and below the front end portion of the head pipe support portion 34.

An intermediate portion 36 is formed between the head pipe support portion 34 and the mounting arm portions 16 and 17, and a maintenance hole 37 that also serves as a meat removal is formed therein.
The upper and lower portions of the intermediate portion 36 are formed as an upper edge and a lower edge that are bent inwardly and integrally into the vehicle body, and the vehicle inner side front end portions of the upper edge portion and the lower edge portion are further bent upward or downward. A flange-like upper flange 38 and lower flange 39 are formed. The upper flange 38 and the lower flange 39 are provided so as to face the left and right divided portions of the main frame, and are brought into contact with each other and integrated by fastening. The upper flange 38 and the lower flange 39 correspond to the upper edge contact surface and the lower edge contact surface of the present invention.

The lower flange 39, which is the lower edge contact surface, extends from the rear of the head pipe 14 to below the upper end of the head cover 32, which is the upper end of the engine. By providing the long lower flange 39 in this way, the rigidity on the lower side of the main frame 15 requiring high rigidity can be increased.
The upper flange 38 that is the upper edge contact surface extends from the rear of the head pipe 14 to the front end of the engine in the longitudinal direction of the vehicle at a portion above the upper end of the engine and is shorter than the lower flange 39. ing. When the length of the upper flange 38 is A and the length of the lower flange 39 is B, A <B.

Reference numeral 40 in the drawing denotes a first fastening portion that joins the left and right boss portions 35 by fastening. Reference numeral 41 denotes three second fastening portions that are provided in the vertical direction along the rear side of the head pipe 14 at the boundary between the head pipe support portion 34 and the intermediate portion 36.
Reference numeral 42 denotes two third fastening portions provided on the upper flange 38 in the front-rear direction.
Reference numeral 43 denotes three fourth fastening portions provided on the lower flange 39 in the front-rear direction.
Reference numeral 44 denotes a fifth fastening portion that connects the left and right vicinity of the upper side of the rear end portion of the maintenance hole 37 at the middle portion in the front-rear direction of the main frame 15.
Reference numeral 45 denotes a sixth fastening portion that fastens the front portion of the mounting arm portion 16 and the front end of the seat rail 22 to the boss 33 on the back surface of the cylinder head 31.
Reference numeral 46 denotes a seventh fastening portion for attaching the rear end portion of the attachment arm portion 16 to the crankcase 18.
Reference numeral 47 denotes an eighth fastening portion for attaching the rear end portion of the attachment arm portion 17 to the crankcase 18.

The fastening parts 40 to 44 are parts for forming the front vehicle body frame 2 by fastening and integrating the left and right divided parts constituting the main frame 15 with each other, and each is constituted by a bolt and a nut. The detailed structure of each fastening portion will be described later.
In addition, it is arbitrarily possible to make the 1st-5th fastening parts 40-44 among these fastening parts into the connection part by coupling means (for example, welding) other than fastening.

  Reference numeral 48 in FIG. 2 is a stay for fixing the bottom front side of the fuel tank 4, and although not clear from this figure, the lower end is fixed to the right side portion of the main frame 15, and the upper end that is bent and rises is the fuel tank 4. It is fastened and coupled to the bottom lower surface of the steel plate with a pile bolt. Reference numeral 4a denotes mounting stays projecting downward provided on the left and right sides of the bottom of the fuel tank 4, and are coupled to a bracket 49 provided near a portion to which the subframe 23 of the seat rail 22 is connected by a bolt 49a. . The fuel tank 4 is supported at three points on the vehicle body frame at these three locations (the stay 48 and the left and right mounting stays 4a). Note that the stay 48 and the bracket 49 are omitted in the drawings after FIG.

A straight line L1 in FIG. 2 is a vertical line passing through the front end of the engine (in this embodiment, the front front end of the cylinder head cover 32 in a side view), and the third fastening portion 42 is positioned forward of this line, and the upper flange 38 The rear end is located behind the straight line l1. Further, on the straight line L1, a front end portion P2 (FIG. 8) of a front opening portion 56 described later is substantially located.
The straight line L2 is a horizontal line passing through the upper end of the engine (in this embodiment, the upper rear end of the cylinder head cover 32 in a side view), and the first fastening portion 40, the second fastening portion 41, and the third fastening portion 42 are located above this line. And the 5th fastening part 44 is located, and the 6th fastening part 45, the 7th fastening part 46, and the 8th fastening part 47 are located below. The fourth fastening portion 43 is located above and below this straight line L2.

  Next, the vehicle body frame structure will be described in more detail. 3 is a perspective view showing the vehicle body frame obliquely from above, FIG. 4 is a plan view thereof, FIG. 5 is a front view, FIG. 6 is a perspective view showing the vehicle body frame obliquely from the rear without the rear vehicle body frame 5, and FIG. FIG. 8 is a perspective view showing the assembled rear body frame 5 from the direction of arrow Z in FIG. 1, and FIG. 9 is a perspective view of the head pipe 14. FIG. 10 is a perspective view showing the outer side surface of the left main frame portion constituting the main frame 15, and FIG. 11 is a perspective view showing the opposite side (inner side surface).

As can be seen from these drawings, the main frame 15 is composed of a left main frame portion 15L which is a left-side divided body having a substantially antipodal structure divided into left and right sides, and a right main frame portion 15R which is a right-side divided body. The main frame portion 15L and the right main frame portion 15R are opposed to each other to form a middle-matching structure, and are integrated with each other by fastening.
In the following description, the structural portions of the left and right common portions will be described using common symbols that do not distinguish between left and right in principle, in order to avoid complexity.

  Similarly, the rear body frame 5 includes a pair of left and right seat rails 22 and sub-frames 23 and 24, which are integrated as a whole. In order to distinguish these from left to right, R is added to the right side and L is added to the left side (FIG. 3).

  Reference numerals 22a, 22b in FIGS. 3, 7, 8 and the like are cross members that connect the left and right seat rails 22R, 22L. The front cross member 22a is provided in the vicinity of the upper end connection portion of the subframe 23, and the rear The cross member 22 b is provided in the vicinity of the upper end connection portion of the subframe 24.

  In a plan view and a top view of the main frame 15 (FIGS. 4 and 8), the head pipe support portion 34 including the boss 35 has a substantially U shape that expands in a bifurcated shape toward the front, and this substantially U shape. In this space, a head pipe 14 that is cylindrical and formed by an appropriate method such as casting is accommodated long in the vertical direction, and the head is connected by fastening with the first fastening portion 40 and the second fastening portion 41 at the front and back. The pipe 14 and the main frame 15 are integrated. The left main frame portion 15L and the right main frame portion 15R are further connected and integrated by third to fifth fastening portions 42 to 44 to become the front body frame 2.

  The front body frame 2 assembled in this way forms a widened portion in which the rear portion on the rear side of the middle portion 36 widens to the left and right and overlaps the left and right side surfaces of the engine 3. As shown in FIGS. 4, 7, 8, 9, etc., a substantially U-shaped rear open portion 55 that is opened in the front-rear direction is formed on the rear side of the upper flange 38. . The rear opening portion 55 opens widely from the seventh fastening portion 46 at the rear end of the mounting arm portion 16, which is a fastening portion with the crankcase 18, to the upper side of the cylinder head cover 32, and the edge portion thereof is edged by a lateral flange 52. ing. The front end portion P1 is on the vehicle body center C close to the rear end portions of the left and right upper flanges 38. The left and right portions of the opening edge of the rear opening 55 are formed by the upper surface of the mounting arm 16.

  As is apparent from FIG. 4, the head cover 32 and the vaporizer 20 face the inside of the rear opening 55 so that maintenance can be performed from above. In FIG. 4, on the vehicle body center line C, the left main frame portion 15L and the right main frame portion 15R are fastened to join the third and fourth fastening portions 42 and 43 and the boss 33 in the fifth fastening portion 45. And the boss | hub 53 in the 6th fastening part 46 is each located.

As shown in FIG. 6, the vaporizer 20 is located behind the collar 44c, the boss 33 and the collar 45c, and the left and right mounting arm portions 16, and is in a position where maintenance is easy and protection from flying stones and the like is provided.

  As shown in FIG. 8, a sufficient distance is maintained between the boss 33 and the cross member 22a, and the carburetor 20 and the like can be maintained through this interval. The left and right seat rails 22R and 22L are connected to each other at the rear ends and have a substantially U shape as viewed from above.

  As apparent from FIGS. 5, 7, 8, etc., a substantially U-shaped front opening portion 56 opened in the front-rear direction is provided on the lower surface of the rear side of the main frame 15. As is apparent from FIG. 5, the front opening 56 is edged by a horizontal flange 57 bent substantially inward in the same manner as the horizontal flange 52, and its front end (upper end) P <b> 2 is the rear end of the lower flange 39. It is located on the vehicle body center C in the vicinity of the part. Further, the left and right portions of the front opening 56 are formed by the lower surface of the mounting arm 17.

  As apparent from FIG. 5, the front portion of the engine 3, particularly the front portions of the cylinder block 30 and the cylinder head 31, face the front opening portion 56, and an exhaust port 58 is provided on the front surface of the cylinder head 31. It opens toward the right diagonally at a position slightly to the right of the vehicle body center. In this way, by exposing the front surface of the cylinder portion 19 such as the cylinder head 31 centering on the exhaust port 58 that becomes a high temperature due to the exhaust temperature to the front of the vehicle body, it is possible to bring the traveling wind into contact therewith and cool it.

  As apparent from FIGS. 4 and 8 and the like, the upper surfaces of the left and right intermediate portions 36 are upper edge portions 36a bent substantially horizontally in the direction of the vehicle body center C to form a ceiling portion. The opposing end portions (front end portion on the vehicle body center side) of the left and right upper edge portions 36a are bent upward again to form the upper flange 38. The left and right upper flanges 38 corresponding to the upper edge contact surface of the present invention face each other in the left-right direction, abut against each other, and are coupled by fastening at the third fastening portion 42. For this reason, the left and right upper edge portions 36a connect the left and right intermediate portions 36 to form a substantial cross member. Since the cross member-like structure portion has a relatively large area in the front-rear direction, it functions as a highly rigid cross member, and the rigidity of the main frame 15 can be increased.

  As is apparent from FIG. 5 and the like, the lower surfaces of the left and right intermediate portions 36 are also bottom edge portions 36b that are bent substantially horizontally in the vehicle body center C direction. The opposite end portions (front end portion on the vehicle body center side) of the left and right lower edge portions 36b are bent downward again to form the lower flange 39. The left and right lower flanges 39 corresponding to the upper edge contact surface of the present invention are in contact with each other in the left-right direction, and are joined by fastening at the fourth fastening portion 43. For this reason, the left and right lower edge portions 36b connect the left and right intermediate portions 36 to form a substantial cross member. Since the cross member-like structure portion has a relatively large front-rear area, the rigidity of the main frame 15 can be increased. In addition, since it is larger than the area of the upper edge portion 36a, the rigidity on the lower side of the main frame 15 can be further increased.

  Further, as apparent from FIG. 8, the front end portion P2 of the front opening portion 56 is located rearward of the front end portion P1 of the rear opening portion 55, and the opening area thereof is the front opening portion 56 rather than the rear opening portion 55. Is smaller. The size of the open area is also apparent in FIG.

  In addition, as shown in FIG. 2, the length A of the upper flange 38 is shorter than the length B of the lower flange 39, and the length B of the lower flange 39 is such a length as to reach the upper front end of the cylinder head cover 32. The number of fastenings is two at the upper flange 38 and three at the lower flange 39. For this reason, the rigidity in the lower part side of the main frame 15 becomes higher.

  Therefore, when the center of gravity of the vehicle body moves forward during braking, when a large load is applied to the lower side of the main frame 15, the lower flange 39 side has a large number of fastenings and is long, and the lower side of the main frame 15 is Since it has a highly rigid structure in advance, it can withstand this force. In addition, when a load is applied in the left-right direction of the vehicle, a force is applied to the left main frame portion 15L and the right main frame portion 15R in a direction in which the divided portions are brought into contact with each other. Since it is highly rigid by abutting and joining by fastening, it can be received by these upper flange 38 and lower flange 39, and the rigidity can be sufficiently enhanced even in a divided configuration.

Moreover, by providing the rear opening 55 having a large opening area on the upper side of the main frame 15, a large opening for maintenance of the cylinder portion can be secured to improve the maintainability.
In addition, by providing the front opening portion 56 having a small opening area, the front of the cylinder portion 19 centering on the cylinder head 31 is opened while securing the rigidity on the lower side of the main frame 15, so that from the front Can be introduced into the front portion of the cylinder portion 19 with the cylinder head 31 as the center, and the periphery of the exhaust port 58 where the temperature becomes particularly high can be cooled, so that the cooling efficiency of the engine 3 can be improved. .

FIG. 9 is a perspective view of the head pipe 14. On the front surface of the head pipe 14, collars 40 c are horizontally integrated at two locations, such as by welding. The interval between the upper and lower collars 40 c is the same as the interval between the upper and lower boss portions 35.
Three collars 41c are similarly attached to the back surface of the head pipe 14 in the vertical direction. Of these, the three collars 41c correspond to the second fastening portions 41 provided in the vertical direction.
In this embodiment, the head pipe 14, the collar 40c and the collar 41c are integrated by welding, but they may be integrally formed by casting.

  In this way, as shown in FIGS. 4 and 5, the head pipe 14 is put inside the left and right head pipe support portions 34, and the bolts 40 b and 41 b are attached at the first fastening portion 40 and the second fastening portion 41. The head pipe 14 and the main frame 15 are firmly integrated by passing through the corresponding collars 40c and 41c and fastening them with the nuts 40a and 41a. For this reason, as in the prior art, the head pipe 14 and the main frame 15 can be firmly integrated without being integrally formed by casting or the like.

  In addition, when one of the head pipe 14 and the main frame 15 needs to be replaced, only one of them can be replaced. Moreover, since the main frame 15 has a left and right divided structure, when the main frame 15 is replaced, it is only necessary to replace either the left or right divided body.

  Furthermore, even when the head pipe 14 having a different shape or structure is replaced due to a change in specifications, if the collars 40c and 41c are common, a new head pipe 14 is inserted between the head pipe support portions 34 and fastened. Since they can be combined, they can be easily exchanged, and the main frame 15 can be used as a common part, so that only the head pipe 14 can be exchanged for another specification.

FIG. 10 is a perspective view showing the outer surface of the left main frame portion 15L, and FIG. 11 is a perspective view showing the opposite side (inner surface). In addition, since the right main frame portion 15R has substantially the same antipodal structure, only the left divided body 15L will be described below.
10 and 11, the left main frame portion 15L is formed at low cost by press-molding an appropriate metal plate such as an iron plate. However, it can be freely formed by casting or forging irrespective of press forming.

The boss portion 35 is provided with a bolt through hole 35a. A boss 59 (FIG. 11) protruding inward is provided in a portion corresponding to the second fastening portion 41 of the head pipe support portion 34, and a bolt through hole 59a is provided in these.
Bolt through holes 38a, 39a, 50a, 51a, 16a and 17a are also formed in the rear ends of the upper flange 38, the lower flange 39, the boss 50, the boss 51 and the mounting arm portions 16 and 17, respectively.
The maintenance hole 37 is in the shape of a long hole extending in the front-rear direction, and the edge thereof forms an annular flange 37a bent inward to reinforce the periphery of the maintenance hole 37.

  The periphery of the left main frame portion 15L is bordered by forming an upper lateral flange 52 and a lower lateral flange 57, and these lateral flanges 52 and 57 form a highly rigid structure. The connecting portion between the mounting arm portions 16 and 17 is a portion where the upper lateral flange 52 and the lower lateral flange 57 are continuously integrated.

  Next, the detailed structure of each fastening portion will be described. 12 is a sectional view taken along line 12-12 of FIG. As is apparent from this figure, a bolt 40b is passed through the collar 40c disposed between the left and right boss portions 35 from the left side of the vehicle body, and is coupled by fastening with a nut 40a on the right side of the vehicle body. The bolt 40b and the nut 40a may be opposite to each other (the same applies to the following fastening portions).

  The second fastening portion 41 has the same structure, and a collar 41c provided on the back side of the head pipe 14 is disposed inside the boss portions 59 of the left and right head pipe support portions 34, and the bolt holes 59a are formed in the holes of the collar 41c. And is coupled by fastening with a nut 41a through a bolt 41b.

  13 is a cross-sectional view taken along line 13-13 of FIG. 2 relating to the third fastening portion 42 and the fourth fastening portion 43. FIG. The left and right intermediate portions 36 are aligned with the left and right upper flanges 38 and the lower flange 39 from the left and right on the vehicle body center C, and the third fastening portion 42 passes the bolts 42b through the both upper flanges 38 and the nuts 42a on the other side. By connecting by fastening, it is integrated. In the fourth fastening portion 43, the bolts 43b are passed through the lower flanges 39 and joined together by fastening with nuts 43a on the other side.

  In this fastened state, the left and right intermediate portions 36 are bent substantially horizontally from the upper and lower ends thereof and have upper and lower edges 36a and 36b that are continuous with the upper flange 38 and the lower flange 39. Although a maintenance hole 37 is formed in part and a bottom wall part, a high rigidity is realized because it has a box shape with a closed cross section as a whole.

  In addition, the upper edge portion 36a and the lower edge portion 36b function as cross members when the left and right intermediate portions 36 are substantially connected to each other, so that the rigidity of the intermediate portion 36 can be increased and the cross member as a separate member can be omitted. Reduces the number of points and facilitates assembly.

  Further, since the left and right upper flanges 38 and the lower flange 39 are combined and fastened together with the nut 42a and the bolt 42b, and the nut 43a and the bolt 43b, the collar can be omitted between the left and right upper flange 38 and the lower flange 39, and is short. Can be connected by fastening with bolts.

  14 is a cross-sectional view taken along line 14-14 of FIG. As shown in this figure, the left and right intermediate portions 36 are integrated by inserting a long collar 44c between the left and right bosses 50, passing a bolt 44b through the collar 44c, and fastening with a nut 44a. The boss 50 is recessed inward from the outer surface, and the heads of the nut 44a and the bolt 44b are accommodated in the recess.

  15 is a cross-sectional view taken along the line 15-15 in FIG. 2 with respect to the sixth fastening portion 45. A pair of left and right collars 45c, 45c are arranged on the left and right of the boss 33 integral with the cylinder head 31, and these collar 45c, boss 33, and The collar 45c is integrated by being fastened with a nut 45a through a bolt 45b. The left and right collars 45 c are integrally welded at the outer ends of the left and right portions 22 R and 22 L of the seat rail 22.

The boss 51 protrudes outward from the mounting arm portion 16, and the inner surface has a concave shape, and the outer end portion of the collar 45 c is fitted and positioned in the concave portion on the inner surface side.
The lateral flange 52 is formed by bending from the upper and lower edge portions of the mounting arm portion 16 and bending inward substantially inward, thereby increasing the rigidity of the mounting arm portion 16. Further, by being coupled to the cylinder head 31 separately from the crankcase 18, the load applied to the engine 3 can be distributed to the cylinder head 31, and concentration of force on the crankcase 18 can be avoided.
In addition, since the seat rail 22 can be mounted in common with the sixth fastening portion 45 that is a mounting member of the mounting arm portion 16, the number of parts can be reduced, and there is no need to provide a dedicated boss for mounting the seat rail 22 on the engine. The mounting is also easy.

  16 is a cross-sectional view taken along line 16-16 in FIG. 2 relating to the seventh fastening portion 46, and collars 46c are arranged on the left and right of the boss 53 provided near the back side base portion of the cylinder block 30 on the upper surface of the crankcase 18. The bolts 46b are passed through them and integrated by fastening with nuts 46a. The lateral flange 52 surrounds approximately half of the outer periphery of the collar 46c and positions the outer end of the collar 46c.

  The eighth fastening portion 47 has the same structure as the seventh fastening portion 46 and is fastened to a boss 54 (FIG. 5) provided at the front portion of the crankcase 18.

Note that the present invention is not limited to the above-described embodiments, and various modifications and applications can be made within the principle of the invention. For example, in the above-described embodiment, the coupling by fastening is described for the coupling between the left and right main frame components, but they may be coupled by welding instead of fastening.
In addition, the length B of the lower flange 39 is made longer than the length A of the upper flange 38 to make the lower side of the main frame 15 highly rigid, and the opening area 56 of the front opening section 56 is larger than the opening area of the rear opening section 55. The invention in which the open area is reduced and the lower side of the main frame 15 is highly rigid is not necessarily used in the same body frame structure, and each may be provided alone.

Side view of motorcycle according to embodiment Enlarged view of the main part Perspective view showing the body frame from the side Plan view of body frame Front view of body frame The perspective view which shows the body frame which omitted the rear body frame from the rear side Perspective view of assembly of front body frame and rear body frame The figure which shows the said assembly from the Z arrow direction of FIG. Head pipe perspective view The perspective view which shows a left main frame part from the outer surface side The perspective view which shows the said division body from the inner surface side 12-12 sectional view of FIG. Sectional view along line 13-13 in FIG. 14-14 sectional view of FIG. Sectional view taken along line 15-15 in FIG. 16-16 sectional view of FIG.

Explanation of symbols

2: Front body frame, 3: Engine, 5: Rear body frame, 14: Head pipe, 15: Main frame, 16: Mounting arm, 17: Mounting arm, 18: Crankcase, 19: Cylinder, 20 : Vaporizer, 31: cylinder head, 32: head cover, 38: upper flange (upper edge contact surface), 39: lower flange (lower edge contact surface), 40: first fastening portion, 41: second fastening portion , 42: third fastening part, 43: fourth fastening part, 44: fifth fastening part, 45: sixth fastening part, 46: seventh fastening part, 47: eighth fastening part

Claims (6)

A front body frame is formed by the head pipe and a main frame extending from the head pipe toward the crankcase of the engine, and a rear end portion of the main frame is attached to the front of the engine so that the engine is attached to the body frame. In the body frame structure of the motorcycle used for the part,
The main frame includes a left main frame portion and a right main frame portion that are formed separately on the left and right sides and are combined and integrated with each other.
The left main frame portion and the right main frame portion are provided with lower edge contact surfaces facing the lower portions thereof, and the lower frame contact surfaces are brought into contact with each other to form the main frame. And
The vehicle body frame structure for a motorcycle, wherein each of the lower edge contact surfaces extends from the rear of the head pipe to below the upper end of the engine. 2. The left main frame portion and the right main frame portion are provided with upper edge abutting surfaces opposed to each other, and the upper edge abutting surfaces are brought into contact with each other to be coupled to each other. The body frame structure of a motorcycle described in 2. The main frame has an expanding portion that branches and expands left and right so that the rear portion overlaps the left and right side surfaces of the engine, and is fastened to the crankcase at each rear end of the left and right expanding portions. The body frame structure of a motorcycle according to claim 2. The left and right widened portions form a rear opening portion that is opened in the vehicle front-rear direction behind the upper edge contact surface on the rear upper side of the main frame,
Forming a front opening part opened in the vehicle front-rear direction behind the lower edge contact surface on the lower rear side of the main frame,
The body frame structure for a motorcycle according to claim 3, wherein an opening area of the front opening portion is smaller than an opening area of the rear opening portion. 5. The body frame structure for a motorcycle according to claim 4, wherein the rear opening portion opens from a fastening portion between the crankcase and the main frame to above the cylinder head portion. The motorcycle according to claim 3, wherein the main frame is fastened to a cylinder portion in addition to the crankcase, and the front end of the seat rail is fastened and supported together at a fastening portion with the cylinder portion. Body frame structure.

Images