JP4008095B2 - Body frame structure of motorcycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a body frame structure of a motorcycle, and more particularly to a structure of a side frame thereof.
[0002]
[Prior art]
The body frame of the motorcycle includes a main frame that extends substantially horizontally behind the engine to support the fuel tank, a center frame that is disposed vertically from the rear to the rear of the engine, and the center frame. A seat rail that extends rearward from the upper portion of the seat substantially horizontally to support the seat, and a side frame that is provided obliquely upward from the lower portion of the center frame and connected to the seat rail, and pivots to the lower portion of the center frame. It is known that a part is provided and a front end part of a rear fork is pivotally attached to the pivot part so as to be swingable in the vertical direction.
[0003]
[Problems to be solved by the invention]
By the way, the side frames are provided as a pair of left and right, and each crosses the rear fork in a side view. For this reason, a space is required between the left and right side frames so that the front part of the rear fork can pass in the front-rear direction, and as a result, the rear fork front part is approximately the total thickness of the left and right side frames. It will project to the side rather than the width, and the vehicle width will increase accordingly.
[0004]
Therefore, a side frame structure that can make the vehicle body as slim as possible is desired. On the other hand, the vehicle body rigidity and strength must be maintained at a predetermined level. The present invention satisfies this requirement.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a first invention relating to a body frame of a motorcycle according to the present application includes a pivot shaft that is provided at a substantially central portion of the vehicle body and rotatably supports a front end portion of a rear fork, An automatic 2 provided with a seat rail that extends upward to the rear of the vehicle body and supports the seat, and a side frame that extends obliquely upward while crossing the side of the rear fork from below the pivot shaft and contacts the seat rail In the vehicle body frame structure of the wheel car, a recess is formed inside a portion intersecting the rear fork in a side view of the side frame, and a bracket is brought into contact with the vicinity of the recess ,
The bracket is a plate-like member, and one side portion is longer than the length of the concave portion forming portion, and the one side portion is in contact with the outer peripheral portion of the concave portion forming portion and is welded .
[0006]
According to a second invention, in the first invention, the bracket is a step bracket, and the step is supported here.
[0007]
【The invention's effect】
Since a recess that allows the front part of the rear fork to pass in the front-rear direction is provided in the inner part of the side frame that intersects the rear fork in a side view, the side frame extends from the left and right sides toward the side of the rear fork. It can be brought to the center of the car. Accordingly, the vehicle body width can be reduced accordingly.
[0008]
Further, since the bracket is attached in the vicinity of the recessed portion forming portion, the recessed portion of the side frame can be reinforced by the bracket, and the vehicle body rigidity and strength can be maintained even though the recessed portion is formed.
[0009]
In addition, if this bracket is used as a step bracket, it is a part that is usually equipped with a step. Therefore, the step bracket for supporting this step can be used effectively with multiple functions, increasing the number of parts. Can be prevented.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, the structure of a motorcycle to which the embodiment is applied will be outlined. FIG. 2 is a left side view in the traveling direction of the appearance of the motorcycle, and FIG. 3 is a side view of the entire body frame. The motorcycle is configured as an American type, and includes a front wheel 1 and a rear wheel that form a long wheel base. 2. It has characteristic structures such as a front fork 3 having a large caster angle, a drop handle 4, a teardrop type fuel tank 5, a tandem seat 6 having a relatively low mounting position, and a backrest 7 provided at the rear part thereof.
[0011]
The engine 8 disposed between the front and rear wheels is a horizontal engine in which an air-cooled cylinder portion 9 is laid substantially horizontally in the front-rear direction. The engine 8 sucks air-fuel mixture from a carburetor 10 disposed above the cylinder portion 9 and is exhausted through an exhaust pipe 11 and a muffler 12 that extend rearward from the lower portion of the cylinder portion 9.
[0012]
The carburetor 10 is supplied with fuel from the fuel tank 5 and is supplied with fresh air from the rear air cleaner 13. The carburetor 10 is disposed in a space sandwiched between a pair of left and right front side covers 14 provided below the fuel tank 5.
[0013]
The front side cover 14 is provided in a space below the front portion of the fuel tank 5 and above the cylinder portion 9, and the front end portion covers the side of the horn 15, and various electrical components are placed between the horn 15 and the vaporizer 10. It comes to arrange. The horn 15 is also an electrical component.
[0014]
The engine 8 is supported by a front portion of a vehicle body frame having a substantially loop shape in a side view (FIG. 2), and the front portion includes a head pipe 16, an upper pipe 17, a lower pipe 18, and a pivot plate 20, and the upper pipe 17 Extends rearward from the head pipe 16 along the center of the vehicle body to support the fuel tank 5, and is bent at substantially the center of the vehicle body and extends downward to be connected to the pivot plate 20. The upper pipe 17 is a frame member of a backbone type, and a part of the main frame and the center frame are integrated.
[0015]
The lower pipe 18 is provided as a pair of left and right, extends from the head pipe 16 in the vehicle width direction and extends downward, bends below the cylinder portion 9 and further toward the rear, and overlaps the side of the pivot plate 20 in a side view. And is connected to a cross pipe 21 (FIG. 2) extending through the pivot plate 20 and extending in the vehicle width direction.
[0016]
The rear portion of the vehicle body frame extends from the bent portion of the upper pipe 17 in a pair of left and right sides substantially horizontally and supports the tandem seat 6, and the lower pipe 18 continues from the side of the pivot plate 20 obliquely. A side frame 23 that extends rearward and connects to an intermediate portion of the seat rail 22 has a substantially truss shape.
[0017]
The pivot plate 20 supports the front end portion of the rear fork 24 so as to be swingable in the vertical direction by the pivot shaft 25. The rear fork 24 extends rearward and the rear wheel 2 is rotatably supported at the rear end portion. The A shock absorber 26 is provided between the connecting portion of the seat rail 22 and the side frame 23 and the rear end portion of the rear fork 24.
[0018]
The rear wheel 2 is chain-driven by a chain 29 wound between a driven sprocket 27 concentrically provided on a side surface thereof and a drive sprocket 28 of the engine 8.
[0019]
The front fork 3 is a known telescopic type, and an upper portion thereof is rotatably supported on the head pipe 16 via a bottom bridge 30 and a top bridge 31. A bullet-type headlight 32 and a pair of left and right front blinkers 33 are supported on the bottom bridge 30, and a meter 34 is supported on the top bridge 31.
[0020]
In the figure, reference numeral 35 denotes a front fender, 36 denotes a front number plate, 37 denotes a carrier, 38 denotes a rear fender, 39 denotes a tail lamp, 40 denotes a mud guard, 41 denotes a rear winker, and 42 denotes a rear number plate.
[0021]
Further, 43 is a change pedal, which is provided at a forward position below the cylinder portion 9. 44 is a rider step, 45 is a main stand, 46 is a step bracket attached to the side frame 23, and a tandem step 47 is attached to the rear end thereof.
[0022]
Next, the side frame will be described. 1 is a plan view showing the relationship between a side frame and a rear fork, FIG. 4 is a side view of a portion of the side frame that intersects the rear fork, and FIG. 5 is a sectional view taken along line 5-5 of FIG. The side frame is a pair of round pipes provided on the left and right sides, and a concave portion 50 that is flattened by press molding is formed inside a portion that intersects the rear fork 24 in a side view.
[0023]
The range in which the concave portion 50 is formed is a portion in which the boss portion 51 of the rear fork 24 can be passed in the front-rear direction when the vehicle body is assembled (or disassembled, hereinafter the same). The boss portion 51 of the rear fork 24 is attached to each front end portion of a pair of left and right arm portions 52, and has a maximum width D0 on the front side of the vehicle body from the portion intersecting the side frame. Reference numeral 53 denotes a cross member that connects the left and right arm portions 52.
[0024]
The left and right boss portions 51 sandwich both end portions of the pivot pipe 54 provided on the pivot plate 20, and pass through the long bolt-shaped pivot shaft 25 passed from one side to the left and right boss portions 51 and the pivot pipe 54. The rear fork 24 is swingably supported on the pivot plate 20 by fastening with the nut 55 on the other boss portion 51 side.
[0025]
The recess 50 is formed by squashing the inside of the side frame 23 so as to be substantially semicircular, and the interval D1 between the left and right recesses 50 is substantially equal to a degree slightly larger than D0. The distance D2 between the inner portions of the side frames in the vicinity where the recess 50 is not formed is smaller than D1 and D0, and the difference d between D1 and D2 is approximately the radius of the side frames. Further, the lateral width W, which is the distance between the outer peripheral portions of the side frames 23 in the recessed portion 50 forming portion, is larger than D0. However, in the conventional configuration in which the recessed portion 50 is not formed, the tube diameter of the side frame 23 (not crushed) Where W should be a dimension that is at least twice as large as the circular part), W in this embodiment has a smaller dimension.
[0026]
The pivot plate 20 is a member formed by press molding and having a substantially U-shaped cross section toward the front. The pivot pipe 54 passes between the left and right side walls 56 and passes through the side wall 56. The entire circumference is welded to the wall 56 side. The cross pipe 21 (FIG. 3) also passes between the lower portions of the left and right side walls 56, and both ends thereof are connected and integrated to the side frame 23 by welding. It extends forward in a continuous manner.
[0027]
As shown in FIG. 4, one side 60 of the step bracket 46 having a substantially triangular shape in a side view is brought into contact with and welded to the outer periphery of the side frame in which the recess 50 is formed. The step bracket 46 is a molded product by aluminum casting or the like, and as shown in FIG. 5, a concave portion 61 that protrudes inward is formed in the center portion, thereby making it lightweight and highly rigid. In addition, a stay 62 on which a tandem step 47 is supported is provided at the rear end.
[0028]
Next, the operation of this embodiment will be described. In FIG. 1, the recesses 50 are formed in the left and right side frames that intersect the rear fork in a side view so that the distance D1 between the left and right recesses 50 is slightly larger than D0. Can pass through the boss portion 51 which is the maximum width portion at the front end portion.
[0029]
Moreover, since the recess 50 is crushed on the inside of the side frame 23, the side frame 23 can be brought closer to the rear fork 24 from both the left and right sides by the dimension d. The body can be slimmed.
[0030]
In addition, since the portion provided with the recess 50 is reinforced by the step bracket 46, the rigidity and strength of the vehicle body can be maintained at the required levels, despite the slimming by the recess 50. In addition, since the recessed portion 50 is reinforced by using the step bracket 46, it is not necessary to use a special member, and the number of parts can be reduced and the structure and assembly work can be simplified.
[0031]
The present invention is not limited to the above-described embodiment and can be applied in various ways. For example, it can be reinforced by using a dedicated bracket instead of the step bracket 46. The restriction of the shape is reduced and the degree of freedom is increased. In addition, the concave portion can be realized by a change in wall thickness or the like, and the side frame can be a square pipe or a solid member.
[Brief description of the drawings]
FIG. 1 is a plan view showing the relationship between a side frame and a rear fork. FIG. 2 is a left side view in the direction of travel in the appearance of a motorcycle. FIG. 3 is a side view of the entire body frame. FIG. 5 is a cross-sectional view taken along the line 5-5 in FIG.
8: Engine, 17: Head pipe, 18: Upper pipe, 19: Lower pipe, 20: Pivot plate, 21: Hole, 22: Seat rail, 23: Side frame, 24: Rear fork, 25: Pivot shaft, 46 : Step bracket, 47: Step for tandem, 50: Recess, 51: Boss part, 54: Pivot pipe

Claims (3)

A pivot shaft that is provided substantially in the center of the vehicle body and rotatably supports the front end of the rear fork, a seat rail that extends rearward from the rear fork to support the seat, and a rear fork from below the pivot shaft. A body frame structure of a motorcycle including a side frame that extends obliquely upward while crossing the sides of the vehicle and abuts against a seat rail,
A recess is formed inside the portion intersecting the rear fork in a side view of the side frame, and a bracket is abutted in the vicinity of the recess ,
This bracket is a plate-like member, and one side portion is longer than the length of the concave portion forming portion, and this one side portion is in contact with the outer peripheral portion of the concave portion forming portion and welded. The body frame structure of a wheeled vehicle.   The body frame structure for a motorcycle according to claim 1, wherein the bracket is a step bracket, and the step is supported by the bracket.   The body frame structure for a motorcycle according to claim 1, wherein the bracket is formed with irregularities on the one side.

Images