Title of Invention

BODY FRAME FOR MOTORCYCLE

Abstract

A body frame (F) for a motorcycle, comprising a pipe-like main frame part (2) and a pivotally supporting frame part (3) extending downward from the rear end part of the main frame part (2). The left side half parts of the main frame part (2) and the pivotally supporting frame part (3) are formed of a semi-cylindrical left side frame half body (27L) formed of a series of plate members, and the right side half parts thereof are formed of a semi-cylindrical right side frame half body (27R) formed of a series of plate members. The opposed end parts of these left side frame half body (27L) and the right side frame half body (27R) are connected to each other to form a continuous hollow structure. In this case, each of the frame half bodies (27L, 27R) is formed by pressing a plate-like blank connected body. Thus, the number of components can be reduced, welding workability can be increased, and the yielding of materials can be increased.

Full Text

DESCRIPTION BODY FRAME FOR MOTORCYCLE TECHNICAL FIELD [0001] The present invention relates to an improvement of a body frame for a motorcycle, the body frame including one pipe-shaped main frame portion equipped with a head pipe at the front end, and a pivot-supporting frame portion extending downward from a rear end portion of the main frame portion and supporting a pivot for supporting a rear fork. BACKGROUND ART [0002] Such a body frame for motorcycle is already known, as disclosed in Patent Publication 1. Patent Publication 1: Japanese Patent No. 3548173 DISCLOSURE OF INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0003] In the body frame for a motorcycle disclosed in Patent Publication 1, the main frame portion is formed from a pipe material, and a pair of left and right pivot-supporting frame portions, which are flat plates, are welded to left and right faces on opposite sides of a rear end portion of the main frame portion. In this way, since the main frame portion, which is formed from the pipe material, and the pivot-supporting frame portions, which are formed from a plurality of plate materials, have different structures, the number of constituent members of the body frame increases and, moreover, since there is no continuity between the main frame portion and the pivot-supporting frame portion, welding thereof is time consuming. [0004] The present invention has been accomplished in the light of such circumstances, and it is an object thereof to provide a body frame for motorcycle that enables the number of constituent members to be reduced, the welding workability to be enhanced, and the material yield to be improved. MEANS FOR SOLVING THE PROBLEMS [0005] In order to attain the above object, according to a first aspect of the present invention, there is provided a body frame for a motorcycle, comprising one pipe-shaped main frame portion equipped with a head pipe at the front end, and a pivot-supporting frame portion extending downward from a rear end portion of the main frame portion and supporting a pivot for supporting a rear fork, characterized in that left halves of the main frame portion and the pivot-supporting frame portion are formed from a continuous semi-tubular left frame half formed by pressing a plate-form joined-body blank in which a plate-form first blank on the main frame portion side and a plate-form second blank on the pivot-supporting frame portion side are welded to each other, right halves of the main frame portion and the pivot-supporting frame portion are similarly formed from a continuous semi-tubular right frame half formed by pressing a plate-form joined-body blank in which a plate-form first blank on the main frame portion side and a plate-form second blank on the pivot-supporting frame portion side are welded to each other, one of opposing edges of the left frame half and the right frame half having an opened-out shape via a step, the opposing edges are welded to each other so that the opened-out opposing edge accommodates the other opposing edge so as to form a continuous hollow structure, the plate thickness of the second blank in each of the frame halves being thicker than that of each of the first blanks, and in a joint between the first blank and the second blank of each frame half, outer faces being connected so as to be flush and inner faces being connected via a step therebetween. [0006] (deleted) [0007] Further, according to a second aspect of the present invention, in addition to the first aspect, left and right branching portions branching obliquely rearward are formed on an upper part of the pivot-supporting frame portion, and the branching portions are connected to each other via a connecting plate. [0008] According to a third aspect of the present invention, in addition to the first or second aspect, a pair of left and right hollow seat rail portions are provided so as to be connested to the rear end of an upper part of the pivot-supporting frame portion. the seat rail portions being formed by welding together opposing edges of an outer half and an inner half each made of a plate material. [0009] According to a fourth aspect of the present invention, in addition to the first or second aspect, a pair of left and right seat rail portions each made of a pipe material are provided so as to be connected to the rear end of an upper part of the pivot-supporting frame portion. [0010] According to a fifth aspect of the present invention, in addition to the third aspect, a third blank corresponding to the outer half of each seat rail portion is welded to each joined-body blank, and when forming the frame half by pressing, the outer half is formed at the same time. [0011] According to a sixth aspect of the present invention, in addition to any one of the first to fifth aspects, opposing edges of the left and right frame halves are superimposed on and welded to each other with one of the frame halves on the inside and the other on the outside. [0012] According to a seventh aspect of the present invention, in addition to any one of the first to sixth aspects, a plurality of blanks forming each joined-body blank are joined together by laser welding, and an end portion of the joint is subjected to MIG welding. [0013] According to an eighth aspect of the present invention, in addition to any one of the first to seventh aspects, all of the plurality of blanks forming each joined-body blank are provided with a press reference hole used when pressing. [0014] According to a ninth aspect of the present invention, in addition to any one of the first to eighth aspects, a component mounting boss with a female thread provided on an inner peripheral face is fonned by fianging on a side wall of the frame half. EFFECTS OF THE INVENTION [0015] In accordance with the first aspect of the present invention, since each of the left and right frame halves is formed as a continuous semi-tubular shaped body formed by pressing the plate-fomi joined-body blank in which the plate-form first blank on the main frame portion side and the plate-fonn second blank on the pivot-supporting frame portion side are welded to each other, each frame half can be obtained from a plate material with good yield and, moreover, since the main frame portion and the pivot-supporting frame portion are formed as a continuous hollow structure by welding the left and right semi-tubular frame halves, the body frame can be formed from a small number of constituent members, that is, the left and right semi-tubular frame halves; moreover, the joints of the left and right semi-tubular frame halves are continuous, thus making the welding work thereof easy. Furthermore, in the continuous hollow structure formed from the main frame portion and the pivot-supporting frame portion, stress can easily be dispersed effectively, the concentration of stress is suppressed, and it is therefore possible to cut back on reinforcing members and achieve a light weight. Furthemiore, since the plate thickness of the second blank is set thicker than that of the first blank, high strength can be imparted to the pivot-supporting frame portion, and it is therefore possible for the pivot-supporting frame portion to withstand a large load from the engine and the rear fork without specially reinforcing it or with less reinforcement, thus contributing to a further decrease in the weight of the body frame. Moreover, since one of the opposing edges of the left frame half and the right frame half has an opened-out shape via a step, and the opposing edges are welded to each other so that the opened-out opposing edge accommodates the other opposing edge so as to form a continuous hollow structure, the joint between the opposing edges does not extend outward, thus preventing the frame from becoming large. Furthermore, since in the joint between the first blank and the second blank of each frame half, the outer faces are connected so as to be flush and the inner faces are connected via a step therebetween, even though blanks having different plate thicknesses are used, a step formed in the joint due to the difference in plate thickness is provided on the inner faces and hidden from the outside, thus ensuring that a good appearance is obtained due to the flush outer faces. Because of this, stress generated when pressing the joined-body blank formed by welding these blanks together can be alleviated and the rigidity of the frame can be enhanced. [0016] (deleted) [0017] Moreover, in accordance with the second aspect of the present invention, use of the connecting plate enables a large section modulus to be imparted to the pivot-supporting frame portion while enabling deep drawing of the left and right halves of the pivot-supporting frame portion to be avoided, thereby enhancing the rigidity effectively. [0018] Furthermore, in accordance with the third aspect of the present invention, since sections from the main frame portion to the seat rail portion form a continuous hollow structure, it is possible to reduce the number of constituent members of the body frame, increase the material yield, enhance the welding workability, and disperse the stress. [0019] Moreover, in accordance with the fourth aspect of the present invention, since the pair of left and right seat rail portions, which are made of a pipe material, are provided so as to be connected to the rear end of the upper part of the pivot- supporting frame portion, it is possible to easily cope with various changes to the specification of the seat rail portion. [0020] Furthermore, in accordance with the fifth aspect of the present invention, forming each of the frame halves from the first to the third blanks enables the material yield to be improved and, moreover, selecting materials having different qualities and plate thicknesses for the first, second, and third blanks according to the function and properties of the main frame portion, the pivot-supporting frame portion, and the seat rail portion enables a light-weight, high-performance body frame to be obtained. [0021] In accordance with the sixth aspect of the present invention, the position of welding between the two frame halves is fixed even in a state in which the two frame halves are vertically inverted, thus contributing to an improvement in the welding workability. [0022] Furthermore, in accordance with the seventh aspect of the present invention, the end portion of the laser-welded joints can be reinforced. [0023] Moreover, in accordance with the eighth aspect of the present invention, by fitting the positioning pin of the mold into the reference hole of each blank when pressing the joined-body blank, not only can a predetermined shape be given to each blank, but it is also possible to minimize the load imposed on the laser-welded joint. [0024] Furthermore, in accordance with the ninth aspect of the present invention, unlike a conventional arrangement it is not necessary to provide a weld nut for mounting a component on the side wall of the body frame, thereby contributing to a reduction in cost. BRIEF DESCRIPTION OF DRAWINGS [0025] [FIG. 1] FIG. 1 is a side view of a motorcycle equipped with the body frame of the present invention (first embodiment). [FIG. 2] FIG. 2 is a perspective view of the body frame (first embodiment). [FIG/3] ' FIG. 3 is an exploded perspective view of the body frame (first embodiment). [FIG. 4] FIG. 4 is a side view of the body frame (first embodiment). [FIG. 5] FIG. 5 is a plan view of the body frame (first embodiment). [FIG. 6] FIG. 6 is a rear view of the body frame (first embodiment). [FIG. 7] FIG. 7 is an enlarged sectional view along line 7-7 in FIG. 4 (first embodiment). [FIG. 8] FIG. 8 is an enlarged sectional view along line 8-8 in FIG. 4 (first embodiment). [FIG. 9] FIG. 9 is an enlarged sectional view along line 9-9 in FIG. 4 (first embodiment). [FIG. 10] FIG. 10 is an enlarged sectional view along line 10-10 in FIG. 4 (first embodiment). [FIG. 11] FIG. 11 is an enlarged sectional view along line 11-11 in FIG. 4 (first embodiment). [FIG. 12] FIG. 12 is an enlarged sectional view along line 12-12 in FIG. 1 (first embodiment). [FIG. 13] FIG. 13 is an enlarged sectional view along line 13-13 in FIG. 4 (first embodiment). [FIG. 14] FIG. 14 is a sectional view along line 14-14 in FIG. 13 (first embodiment). [FIG. 15] FIG. 15 is a plan view of a joined-body blank, which is a material for each of left and right frame halves (first embodiment). EXPLANATION OF REFERENCE NUMERALS AND CHARACTERS [0026] F Body frame M Motorcycle 1 Head pipe 2 Main frame portion 3 ' Pivot-supporting frame portion 4 Seat rail portion 4A Outer half 4B Inner half 8 Rear fork 9 Pivot shaft 27L Left frame half 27R Right frame half 027L Joined-body blank corresponding to left frame half 027R Joined-body blank corresponding to right frame half 28 Connecting plate 31 First blank 32 Second blank 33 Third blank 34 Joint between first and second blanks 35 Joint between second and third blanks 37 to 39 Press reference hole 43 Component mounting boss 43 Female thread BEST MODE FOR CARRYING OUT THE INVENTION [0027] A mode for carrying out the present invention is explained below by reference to a preferred embodiment shown in the attached drawings. EMBODIMENT 1 [0028] In FIG. 1, a body frame F of a motorcycle M is formed from one pipe-shaped main frame portion 2 that in going reanA/ard from a head pipe 1 is inclined downward, a pivot-supporting frame portion 3 extending downward from a rear end portion of the main frame portion 2, and a pair of left and right seat rail portions 4 and 4 each formed from an inclined portion 4s extending upward and reanward from an upper portion of the pivot-supporting frame portion 3 and a horizontal portion 4h extending horizontally from an upper end portion of the inclined portion 4s, the head pipe 1 supporting a steering stem 6a of a front fork 6 that supports a front wheel 5f, and handlebars 7 being connected to the upper end of the steering stem 6a. A pivot shaft 9 is fixedly provided on the pivot-supporting frame portion 3, a rear fork 8 that axially supports a rear wheel 5r being vertically swingably supported by the pivot shat 9. An engine E positioned between the front wheel 5f and the rear wheel 5r is mounted on the main frame portion 2 and the pivot-supporting frame portion 3, the power thereof being transmitted to the rear wheel 5r via a chain transmission system 11. A rear cushion 12 is disposed between the rear fork 8 and the seat rail portions 4 and 4. [0029] A luggage box 15 is mounted on upper faces of the pivot-supporting frame portion 3 and the inclined portion 4s of each of the seat rail portions 4, a fuel tank 16 is mounted on an upper face of the horizontal portion 4h, and a pillion rider seat 17 is hinged on a front end portion of the luggage box 15 so that the upper faces of the luggage box 15 and the fuel tank 16 can be opened and closed. [0030] A body cover 18 covering the body frame F and a cylinder part of the engine E is mounted on the body frame F, and a pair of left and right leg shields 19 are provided so as to be connected to the front end of the body cover 18. [0031] In FIG. 1, reference numeral 20 denotes a front fender, 21 denotes a rear fender, 22 denotes a main step, 23 denotes a pillion step, 24 denotes a main stand, and 25 denotes a side stand. [0032] The body frame F is now explained in detail. [0033] First, in FIG. 2 to FIG. 6, left halves of the main frame portion 2 and the pivot-supporting frame portion 3 of the body frame F and an outer half 4A of the left seat rail portion 4 are formed from a semi-tubular left frame half 27L made of a series of metal plate materials, and right halves of the main frame portion 2 and the pivot-supporting frame portion 3 and an outer half 4A of the right seat rail portion 4 are similarly formed from a semi-tubular right frame half 27R made of a series of metal plate materials. Opposing edges, in the main frame portion 2 and the pivot- supf3orting frame portion 3, of the left frame half 27L and the right frame half 27R are joined to each other by MIG welding. Reference numerals 36 denote the MIG welding portions. In this way, the main frame portion 2 and the pivot-supporting frame portion 3 form one continuous hollow structure. [0034] As shown in FIG. 7 and FIG. 8, when welding the two frame halves 27L and 27R together, the opposing edges of the two frame halves 27L and 27R are superimposed on each other and welded with one of the frame halves 27L and 27R on the inside and the other on the outside. By so doing, the position of welding between the two frame halves 27L and 27R is fixed even in a state in which the two frame halves 27L and 27R are vertically inverted, and welding work can easily be carried out. [0035] Referring again to FIG. 2 to FIG. 6, left and right branching portions 3a and 3a branching obliquely rearward are formed in an upper part of the pivot-supporting frame portion 3, these branching portions 3a and 3a being connected to each other via a connecting plate 28. Use of the connecting plate 28 enables a large section modulus to be imparted to the pivot-supporting frame portion 3 while enabling deep drawing of the left and right halves of the pivot-supporting frame portion 3 to be avoided, thereby enhancing the rigidity effectively. Each of the branching portions 3a and 3a and the connecting plate 28 are joined by MIG welding. [0036] A plurality of reinforcing ribs 29 extending in the lateral direction are press molded in the connecting plate 28, these reinforcing ribs 29 increasing the rigidity of the connecting plate 28, thus, the pivot-supporting frame portion 3, and suppressing the generation of vibrational noise. [0037] The left and right seat rail portions 4 and 4 are each formed so as to be hollow by joining opposing edges of the semi-tubular outer half 4A and a semi-tubular inner half 4B by MIG welding (the MIG welding portions here are also denoted by reference numerals 36) (see FIG. 11), the front ends of the outer halves 4A are welded to the rear ends of the branching portions 3a and 3a, and the front ends of the inner halves 48 are welded to the rear end of the connecting plate 28. In this arrangement, the positions of the welding portions of the front ends of the outer half 4A and the inner half 4B are set so as to be displaced from each other in the longitudinal direction of the seat rail portion 4. By so doing, the concentration of stress at the base portion of the seat rail portion 4 can be alleviated. [0038] As shown in FIG. 15, each of the frame halves 27L and 27R uses as a starting material a corresponding plate-form joined-body blank (hereinafter, called a tailored blank) 027L or 027R. These tailored blanks 027L and 027R are formed by joining to each other by laser butt-welding a plate-form first blank 31 corresponding to the left or right half of the main frame portion 2, a plate-fonn second blank 32 corresponding to the left or right half of the pivot-supporting frame portion 3, and a plate-form third blank 33 corresponding to the outer half 4A of the corresponding one of the seat rail portions 4, the left and right tailored blanks 27L and 27R being formed so as to be symmetrical to each other. By press forming these left and right tailored blanks 027L and 027R symmetrically, continuous left and right semi-tubular frame halves 27L and 27R are formed. In the figures, reference numeral 34 denotes a laser-welded joint between the first and second blanks 31 and 32, and reference numeral 35 denotes a laser-welded joint between the second and third blanks 32 and 33. [0039] The first to the third blanks 31 to 33 are each provided with one or a plurality of press reference holes 37 to 39 (see FIG. 4 and FIG. 15); during press forming, by fitting positioning pins of a mold into these reference holes 37 to 39, when subjecting the tailored blanks 027L and 027R to press forming, not only can a predetermined shape be given to each of the blanks 31 to 33, but it is also possible to minimize the load imposed on the laser-welded joints 34 and 35. In the case of the illustrated example, the press reference hole 37 of the first blank 31 employs a though hole for mounting the rod-shaped member 41, and the press reference hole 38 of the second blank 32 employs a though hole for mounting the pivot shaft 9. It is desirable that when carrying out press forming the heat input side of the laser-welded joints 34 and 35 is arranged to be on the inside of the body frame F. [0040] Forming each of the frame halves 27L and 27R with the first to the third blanks 31 to 33 in this way naturally enables the material yield to be improved, and selecting materials having different qualities and plate thicknesses for the first to the third blanks 31 to 33 according to the function and properties of the main frame portion 2, the pivot-supporting frame portion 3, and the seat rail portion 4 enables light weight and high performance to be obtained for the body frame F. [0041] As the second blank 32, a material having a thicker plate thickness than that of the first and third blanks 31 and 33 is selected (see FIG. 9). Since this imparts a higher strength to the pivot-supporting frame portion 3, it is possible for it to withstand a large load from the engine E and the rear fork 8 without specially reinforcing it, or with less reinforcement, thus contributing to a further decrease in the weight of the body frame F. Moreover, since the body frame F, which is formed from the left and right frame halves 27L and 27R, is a continuous hollow structure that includes the main frame portion 2, the pivot-supporting frame portion 3, and the seat rail portions 4 and 4, the body frame F can be formed from a small number of constituent members, that is, the left and right semi-tubular frame halves 27L and 27R and, moreover, since the joints of the left and right semi-tubular frame halves 27L and 27R are continuous, welding work therefor can easily be carried out. Moreover, in the continuous hollow structure that includes the main frame portion 2, the pivot-supporting frame portion 3, and the seat rail portions 4 and 4, stress can be dispersed effectively, the concentration of stress is suppressed, and it is therefore possible to cut back on reinforcing members and achieve a light weight. [0042] Referring again to FIG. 2 to FIG. 6, in the tailored blank, which is the starting material for each of the frame halves 27L and 27R, the laser-welded joint 34 of the first blank 31 and the second blank 32, which have different plate thicknesses, is formed as shown in FIG. 4 so as to be inclined relative to a central line 40 of the main frame portion 2 or, as shown by the broken line, in a peak shape. By so doing, the section modulus gradually changes from the main frame portion 2 to the pivot-supporting frame portion 3, and stress concentration occurring in the joint 34 is V alleviated. Furthermore, the inside and outside of an end portion of the laser-welded joint 34 are subjected to MIG welding. This is effective in reinforcing the end portion of the joint 34. That is. in general, with regard to a laser-welded joint, a welding start portion is cut off after welding in order to achieve uniformity of welding strength. In contrast, in this embodiment, by MIG welding to the end of the laser-welded joint 34, it is unnecessary to cut off a welding start portion, the strength of the joint 34 increases, and at the same time the material yield can be improved. Such a technique can also be applied to the joint 35 between the second and third blanks 32 and 33. [0043] In the main frame portion 2, the cross section, as shown in FIG. 7 and FIG. 8, is a polygon, and is an octagon in the illustrated example. Moreover, its cross-sectional area is a minimum in a longitudinally middle section of the main frame portion 2 and increases toward the front and the rear. This can impart to each portion of the main frame portion 2 a strength corresponding to the bending moment acting thereon, and by selecting the number of corners of the polygonal cross section the rigidity of the main frame portion 2 can easily be set. Such an arrangement of the main frame portion 2 can easily be achieved by joining opposing edges of the left and right semi-tubular frame halves 27L and 27R. This can also eliminate the need for welding a gusset between the head pipe 1 and the main frame portion 2. [0044] As shown in FIG. 4 and FIG. 7, in a front end portion of the main frame portion 2 where there is a relatively large cross-sectional area, left and right side walls are integrally connected via the rod-shaped member 41 running therethrough, thereby strengthening the rigidity of the front end portion of the main frame portion 2 and suppressing vibrational noise. Threaded holes 41a and 41a are formed in two end portions of this rod-shaped member 41, which project from opposite outside faces of the main frame portion 2, and they are used for mounting, for example, the body cover 18. [0045] As shown in FIG. 2 to FIG. 4 and FIG. 8, a plate-form engine hanger 44 is welded to each of left and right side faces of the rear end portion of the nfiain frame portion 2. This engine hanger 44 is therefore positioned further fonA^ard than the joint 34 between the first and second blanks 31 and 32. This engine hanger 44 is provided for supporting an upper part of the engine E. A front wall of the pivot-supporting frame portion 3 is open in a portion beneath a portion connected to the main frame portion 2, and a pair of upper and lower engine mounting holes 46 and 46 are provided in left and right side walls of the pivot-supporting frame portion 3 in the vicinity of this open portion 45. These mounting holes 46 and 46 are provided for mounting a rear part of the engine E that is inserted into the open portion 45. By so doing, it is possible by means of the main frame portion 2 and the pivot-supporting frame portion 3 to disperse and support the load of the engine E acting on the body frame F, thus alleviating the concentration of stress at the joint 34, and it is also possible to use the engine E as a strengthening member for the pivot-supporting frame portion 3. A stay 42 for supporting the body cover 18 is attached to the engine hanger 44. [0046] The plate thickness of the plate-form engine hanger 44 is set the same as that of the pivot-supporting frame portion 3. The plate thickness of the engine hanger 44 is therefore thicker than the plate thickness of the main frame portion 2, and it is thus possible to obtain a high strength engine hanger 44. Moreover, since the shape of the pivot-supporting frame portion 3 is relatively complicated, when stamping the second blank 32, which is a starting material, large pieces of scrap are produced, and since the engine hanger 44 can be obtained by using the scrap, the material yield can be improved. [0047] As shown in FIG. 10, component mounting bosses 43 with a female thread 43a provided on an inner peripheral face are formed by flanging in portions of the side wall of each of the frame halves 27L and 27R, and various components are joined thereto by bolting. Unlike a conventional arrangement it is therefore unnecessary to use a weld nut for mounting a component, thus contributing to a V reduction in cost. An insertion-fixing hole 63 for a clamper 62 supporting a wire harness 61 is provided in the frame half on the side opposite to the component mounting boss 43. [0048] As shown in FIG. 2, FIG. 4, and FIG. 5, the left and right seat rail portions 4 and 4 are connected to each other in their middle sections and rear end portions via a pair of front and rear cross members 57 and 58. A support platform 59 is projectingly provided on an upper part of the inclined portion 4s of each of the seat rail portions 4, and the fuel tank 16 is mounted on the support platforms 59 and bosses 56 and 56 provided on upper faces of rear parts of the left and right seat rail portions 4 and 4. They are also used for supporting the seat 17. [0049] As shown in FIG. 4 and FIG. 11, a bracket 60 is welded to each of the left and right side faces of each of the seat rail portions 4 throughout a section from the inclined portion 4s to the horizontal portion 4h, and this bracket 60 is used for supporting an upper end portion of the rear cushion 12. By setting the plate thickness of this bracket 60 the same as that of the outer and inner halves 4A and 4B of each of the seat rail portions 4, the bracket 60 can be obtained from scrap produced when stamping the outer and inner halves 4A and 4B from starting material, thus improving the material yield. [0050] As shown in FIG. 1 and FIG. 12, the luggage box 15 is placed on an upper face of the connecting plate 28 so that a pair of left and right mount rubbers 52 and 52 are held therebetween, and by screwing a pair of bolts 53 and 53 running through a base wall of the luggage box 15 and the mount rubbers 52 and 52 into a pair of left and right weld nuts 54 and 54 provided on a lower face of the connecting plate 28, the luggage box 15 is resiliently supported by the connecting plate 28. In this arrangement, distance collars 55 and 55 fitted around the outer periphery of the bolts 53 and 53 are disposed between a head part of each of the bolts 53 and 53 and the connecting plate 28 so that an excessive compressive load does not act on the mount rubbers 52 and 52. In this way, since the connecting plate 28 functions as a support member for the luggage box 15 while forming a ceiling part of the pivot-supporting frame portion 3, the arrangement can be simplified. [0051] As shown in FIG. 4 and FIG. 6, the pivot shaft 9 is welded to the left and right side walls of the pivot-supporting frame portion 3 so as to run therethrough, thereby increasing the strength of the pivot-supporting frame portion 3. The rear fork 8 is vertically swingably supported by opposite end portions of the pivot shaft 9 projecting outside from the left and right side walls of the pivot-supporting frame portion 3. [0052] As shown in FIG. 4, FIG. 13, and FIG. 14, a pair of stand support bosses 48 and 48* projecting inward and supporting opposite end portions of a pivot 47 of the main stand 24 are formed integrally with the left and right side walls of a lower end portion of the pivot-supporting frame portion 3, and these stand support bosses 48 and 48' are formed by flanging. In this arrangement, one flat wall 48a or a pair of opposing flat walls 48a are formed on the left stand support boss 48, and the flat wall 48a is superimposed on a flat face 47a formed on the outer periphery of the pivot 47 at a predetermined position, thus preventing the pivot 47 from rotating. It is therefore unnecessary to provide a special detent member between the pivot 47 and the stand support boss 48, thus reducing the number of components. [0053] The right hand end portion of the pivot 47 is also used for supporting a brake pedal 49. A split pin 50 or a circlip is mounted on an outer end portion of the pivot 47 projecting outward from the left stand support boss 48 in order to prevent the pivot 47 from falling out. [0054] An embodiment of the present invention is explained above, but the present invention is not limited to the above-mentioned embodiment and may be modified in a variety of ways as long as the modifications do not depart from the spirit and scope of the present invention. For example, when auxiliary equipment other than the luggage box 15, such as the fuel tank 16, is disposed above the connecting plate 28, the connecting plate 28 may also be used as a member for supporting the auxiliary equipment. Furthermore, instead of the left and right split seat rail portions 4, a seat rail portion made of a pipe material may be used. CLAIMS [1] (amended) A body frame for a motorcycle, comprising one pipe-shaped main frame portion (2) equipped with a head pipe (1) at the front end, and a pivot-supporting frame portion (3) extending downward from a rear end portion of the main frame portion (2) and supporting a pivot (9) for supporting a rear fork (8), characterized in that left halves of the main frame portion (2) and the pivot-supporting frame portion (3) are formed from a continuous semi-tubular left frame half (27L) formed by pressing a plate-form joined-body blank (027L) in which a plate-form first blank (31) on the main frame portion (2) side and a plate-form second blank (32) on the pivot-supporting frame portion (3) side are welded to each other, right halves of the main frame portion (2) and the pivot-supporting frame portion (3) are similarly formed from a continuous semi-tubular right frame half (27R) formed by pressing a plate-form joined-body blank (027R) in which a plate-form first blank (31) on the main frame portion (2) side and a plate-form second blank (32) on the pivot-supporting frame portion (3) side are welded to each other, one of opposing edges of the left frame half (27L) and the right frame half (27R) having an opened-out shape via a step, the opposing edges are welded to each other so that the opened-out opposing edge accommodates the other opposing edge so as to form a continuous hollow structure, the plate thickness of the second blank (32) in each of the frame halves (27L, 27R) being thicker than that of each of the first blanks (31), and in a joint (34) between the first blank (31) and the second blank (32) of each frame half (27L, 27R), outer faces being connected so as to be flush and inner faces being connected via a step therebetween. (amended) The body frame for a motorcycle according to Claim 1, wherein left and right branching portions (3a, 3a) branching obliquely rearward are formed on an upper part of the pivot-supporting frame portion (3), and the branching portions (3a, 3a) are connected to each other via a connecting plate (28). (amended) The body frame for a motorcycle according to Claim 1 or 3, wherein a pair of left and right hollow seat rail portions (4, 4) are provided so as to be connected to the rear end of an upper part of the pivot-supporting frame portion (3), the seat rail portions (4, 4) being formed by welding together opposing edges of an outer half (4A) and an inner half (4B) each made of a plate material, (amended) The body frame for a motorcycle according to Claim 1 or 3, wherein a pair of left and right seat rail portions (4, 4) each made of a pipe material are provided so as to be connected to the rear end of an upper part of the pivot-supporting frame portion (3). 5 The body frame for a motorcycle according to Claim 4, wherein a third blank (33) corresponding to the outer half (4A) of each seat rail portion (4) is welded to each joined-body blank (027L, 027R), and when forming the frame half (27L, 27R) by pressing, the outer half (4A) is formed at the same time. 6 (amended) The body frame for a motorcycle according to any one of Claims 1 and 3 to 6, wherein opposing edges of the left and right frame halves (27L, 27R) are superimposed on and welded to each other with one of the frame halves (27L, 27R) on the inside and the other on the outside. 7 (amended) The body frame for a motorcycle according to any one of Claims 1 and 3 to 7, wherein a plurality of blanks (31, 32, 33) forming each joined-body blank (027L, 027R) are joined together by laser welding, and an end portion of the joint (34, 35) is subjected to MIG welding. ^ [1^] (amended) The body frame for a motorcycle according to any one of Claims 1 and 3 to 8, wherein all of the plurality of blanks (31, 32) forming each joined-body blank (027L, 027R) are provided with a press reference hole (37, 38, 39) used when pressing. 9 (amended) The body frame for a motorcycle according to any one of Claims 1 and 3 to 9, wherein a component mounting boss (43) with a female thread (43a) provided on an inner peripheral face is formed by flanging on a side wall of the frame half (27L, 27R). 10. The body frame for a motorcycle according to any one of Claims 1 and 3 to 9, wherein a component mounting boss (43) with a female thread (43a) provided on an inner peripheral face is formed by flanging on a side wall {48) of attachedto the frame half (27L,27R). [11] The body frame for a motorcycle according to Claim 1, wherein the main frame portion (2) is formed to have a cross section of a polygon. [12] The body frame for a motorcycle according to Claim 1, wherein an engine hanger (44) for supporting an engine (E) is fixed to the side face of the body frame, and the engine hanger (44) is fixed to the side face of the main frame portion (2) while avoiding a joint (34) formed by welding each half of the main frame portion (2) and each half of the pivot-supporting frame portion (3). [13] The body frame for a motorcycle according to Claim 1, wherein the body frame further includes a pair of left and right seat rail portions (4) extending rearward from a rear end of the pivot-supporting frame portion (3), upper portions of the left and right halves of the pivot-supporting frame portion (3) being connected to each other via a connecting plate (28), each of the seat rail portions (4) being formed from an outer half (4A) and an inner half (4B) each made of plate materials joined to each other, a front end of the outer half (4A) being welded to the frame half (27L, 27R) on the outer side, and a front end of the inner half (4B) being welded to the connecting plate (28) at a position displaced from the front end of the outer half (4A).

Documents:

4893-CHENP-2007 AMENDED CLAIMS 22-12-2011.pdf

4893-CHENP-2007 OTHER PATENT DOCUMENT 22-12-2011.pdf

4893-CHENP-2007 CORRESPONDENCE OTHERS 15-04-2011.pdf

4893-CHENP-2007 CORRESPONDENCE OTHERS.pdf

4893-CHENP-2007 CORRESPONDENCE PO.pdf

4893-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 22-12-2011.pdf

4893-CHENP-2007 FORM-3 22-12-2011.pdf

4893-CHENP-2007 POWER OF ATTORNEY 22-12-2011.pdf

4893-chenp-2007-abstract.pdf

4893-chenp-2007-claims.pdf

4893-chenp-2007-correspondnece-others.pdf

4893-chenp-2007-description(complete).pdf

4893-chenp-2007-drawings.pdf

4893-chenp-2007-form 1.pdf

4893-chenp-2007-form 18.pdf

4893-chenp-2007-form 3.pdf

4893-chenp-2007-form 5.pdf

4893-chenp-2007-pct.pdf