JPH10329776A - Car body frame structure for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fasten a cast frame to an engine. SOLUTION: A cast frame integrated with a head pipe 2 and a main frame 3 is formed by casting and a separate engine bracket 5 is fastened to the rear end part of the main frame 3. The main frame 3 and the engine bracket 5 are fastened to the engine 13 by fastening parts 16, 17, and 18. The fastening member 16 out of them is a direct fitting part, and the main frame 3 and the engine bracket 5 are fastened to each other by this fastening member 16. The fastening members 17, 18 which are indirect fitting parts fasten the engine bracket 5 to the engine 13 so as to fasten the main frame 3 of the cast frame 1 to the engine 13 via the engine bracket 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body frame structure for a motorcycle, and more particularly to a structure for fastening to an engine using a cast frame.

[0002]

2. Description of the Related Art Japanese Utility Model Registration No. 251877 discloses that a main frame portion including a head pipe is formed as a wide hollow monocoque frame having a width substantially equal to a vehicle body width, a pivot plate is welded to a rear end thereof, and an automatic engine supporting an engine is provided. The body frame structure of the motorcycle is shown.

[0003]

By the way, in the structure in which the pivot plate is welded to the monocoque frame as in the above-mentioned conventional example, finishing of the welded portion and dimensional correction by thermal distortion are required, and the number of man-hours is increased.

On the other hand, it is conceivable to integrally cast the pivot plate with the main frame. In this case, however, it is difficult to optimize the rigidity balance by directly fastening the engine to the engine, and to absorb a mounting error due to shape deformation due to casting. The structure for performing the operation becomes complicated.

On the other hand, if a pivot plate having a flat shape is simply manufactured as a separate bracket, and the main frame and the engine are fastened via this bracket, the torsional rigidity is reduced by the fastening portion. Would.

Accordingly, an object of the present invention is to provide a vehicle body frame structure capable of fastening a cast frame to an engine while maintaining rigidity balance.

[0007]

In order to solve the above-mentioned problems, a motorcycle body frame structure according to the present invention comprises a head pipe for supporting front wheels so as to be steerable, and a main frame extending rearward from the head pipe. A head frame and a main frame are formed as an integral casting frame by casting, and the engine bracket to be fastened to the engine is formed in a substantially stepped shape. And the engine bracket is fastened to a part of the casting frame at a step portion thereof.

At this time, the engine bracket and a part of the casting frame can be fastened together to the engine.

Further, the fastening direction between the main frame and the engine bracket may be perpendicular to the fastening direction of the engine bracket to the engine.

[0010]

According to the present invention, when the casting frame is fastened to the step portion of the separate engine bracket and the engine bracket is fastened to the engine, the step-like engine bracket is reinforced by the step portion. Stiffness balance can be properly maintained.

In addition, since the molding distortion of the casting frame can be absorbed by the interposition of the separate engine bracket, the casting frame can be fastened to the engine. In addition, the casting frame stabilizes the quality and reduces the number of working steps.

Further, if the fastening portion of the engine is formed as a jointed structure of the cast frame engine bracket, the number of fastening points can be reduced and the fastening rigidity can be easily secured.

Further, if the fastening direction of the casting frame and the engine bracket is made orthogonal to the fastening direction with respect to each engine, the rigidity of the engine bracket is increased, and the rigidity balance is further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view of an external appearance of a casting frame according to the present invention (a motorcycle mounted with the same is also shown). FIG. 2 is a casting frame along line 2-2 in FIG. FIG. 3 is a cross-sectional view of the vehicle body frame in a state where the lid is mounted along the line 3-3 in FIG. 4, and FIG. 4 is a view in the direction indicated by the arrow X in FIG. 3 (the lid and the air filter are removed). FIG. 5 is a sectional view taken along line 5-5 of FIG.

In these figures, a cast frame 1 formed by using an appropriate light alloy such as aluminum is composed of a head pipe 2 of a front wheel, and a main frame 3 extending diagonally downward in a pair of right and left behind the front pipe. A substantially dish-shaped portion 4 located between the left and right main frames 3 is integrally formed.

At the rear ends of the left and right main frames 3,
An engine bracket 5 manufactured separately by appropriate means such as casting is fastened in a manner described later.

The substantially dish-shaped portion 4 has a substantially dish shape with an open top, and a separate lid 6 is attached to the opening, so that the internal space is used as an air cleaner space 7, and an air filter 8 is provided here. Is installed. The peripheral edge of the lid 6 is sealed and attached to the opening edge on the substantially dish-shaped portion 4 side.

The inside of the space 7 for the air cleaner is formed by an air filter 8 into an annular wall 9 formed at the center of the inside of the substantially dish-shaped portion 4.
Dirty room 7a
And a clean room 7b.

In a clean room 7b, an intake pipe 11 of a carburetor 10 supported on the bottom of the substantially dish-shaped portion 4 is accommodated, and in the dirty room 7a, the carburetor 1 is held at the bottom of the substantially dish-shaped portion 4.
An upper end portion of the intake duct 12 provided to open downward to a position forward from 0 protrudes.

The outside air drawn into the dirty room 7a from the intake duct 12 is purified by the air filter 8,
The air is sent from the clean room 7b to the engine 13 through the intake pipe 11 and the carburetor 10.

The engine 13 is a horizontally opposed two-cylinder water-cooled engine. A front end of a rear arm 15 constituting a rear wheel suspension device is swingably mounted on a mounting portion 14 projecting rearward from a rear end of a crankcase. (FIG. 1).

The rear part of the engine 13 is
And fastening members 16 and 17 to the engine bracket 5.
And 18 are fastened. The upper part of the engine 13 is supported by an engine hanger 19 attached to an intermediate part of the main frame 3.

As is apparent from FIGS. 3 to 5, the left and right main frames 3 each have a substantially U-shaped cross section opened upward, and have an outer wall 20, an inner wall 21, and a bottom wall 22. The inner wall 21 is higher than the outer wall 20 and also serves as a part of the peripheral wall of the substantially dish-shaped portion 4.

A mounting hole 22a is formed in an intermediate portion of the bottom wall 22 of the main frame 3, and a bent upper portion 19a of the engine hanger 19 is overlapped with the mounting hole 22a and fastened with a bolt 23a and a nut 23b. The upper part 19a is the inner wall 2
1 is inserted into the inside through a hole 21a formed in the lower part of FIG. 1 (FIG. 5).

Bosses 24 and 25 are formed integrally with the bottom wall 22 at the rear of the main frame, and are respectively provided with bolt through holes 24a and 25 having their axes oriented in the vertical direction when the vehicle body is completed.
a is formed. A boss 26 is integrally formed on the inner wall 21 where the fastening member 16 is fastened to project toward the center of the vehicle body (FIG. 4).

The peripheral wall of the substantially dish-shaped portion 4 is formed by the left and right inner walls 2.
1 and a front wall 27 and a rear wall 28 integrally formed with the casting frame, and a boss 30 for mounting the lid 6 is formed on the bottom 29 so as to protrude forward and backward with the annular wall 9 interposed therebetween. Have been.

At the rear part of the bottom part 29, a part is bent downward to provide a minimum part 31, where a drain pipe 32 is attached.
With this drain pipe 32, the water accumulated inside is drained substantially below the dish-shaped portion 4.

In addition, a suction port 29a, a discharge port 29b, and a drain port 29c are formed in the bottom portion 29, and the suction duct 12, the suction pipe 11, and the drain pipe 32 are directly attached to these openings, respectively (FIG. 3). And 4).

As shown in FIGS. 3 to 5, the shaft hole 2a of the head pipe 2, the inner and outer walls 20 of the main frame 3,
21, a concave space 3a formed therebetween, the annular wall 9 and its ribs 9a and 9b, a front wall 27 and a rear wall 28 of the substantially dish-shaped portion 4, and a concave space 27 between the front wall 27 and the head pipe 2.
a, boss 30 and its ribs 30a, 30b and bottom 2
The ribs 29d, 29e and the bosses 24 and 25 in the concave space 3a are integrally formed along the same die-cutting direction. It is parallel to the center line C (FIG. 3).

The engine bracket 5 has a substantially stair-like shape as a whole so that it goes deeper into the center of the vehicle body toward the upper part (FIG. 4), and its middle part is vertically aligned with the rear end of the bottom wall 22 constituting the main frame 3. Forming a stepped portion 33 that overlaps with
Here, it is fastened with a bolt 34a and a nut 34b (FIG. 2).

Further, the upper portion 35 extends inside the inner wall 21 to the height of the boss 26, and a through hole 35a is formed therein.
6 is formed so as to coincide with the shaft hole. The through hole 35a is a fastening hole 1 threaded on an inner surface formed across the rear upper mounting portion 13a of the engine 13 in the vehicle width direction.
3b (FIG. 2).

The rear upper mounting portion 13a of the engine 13 and the pair of engine brackets 5 attached to the left and right sides thereof are inserted between the left and right bosses 26, and the holes are aligned so that the fastening member 16 is moved from one of the bosses 26. The main frame 3 and the engine bracket 5 are jointly fastened to the engine 13 by being fastened to the other side with the nut 36, and this fastening portion is directly a mounting portion.

The lower part 3 is located between the left and right engine brackets 5.
7 are located on both sides of a rear lower mounting portion 13c formed at a lower portion of the engine 13, and through holes 37a formed here are provided.
Correspond to the right and left fastening holes 13d formed in the vehicle width direction of the rear lower attachment portion 13c.

Therefore, the fastening hole 1 of the rear lower mounting portion 13c is provided.
The lower portion 37 of the left and right engine brackets 5 is fixed to the rear lower mounting portion 13 of the engine 13 by aligning the 3d with the left and right through holes 37a and fastening the respective portions with the fastening members 18.
c.

The same applies to the fastening structure by the fastening member 17, and each fastening portion by these fastening members 17 and 18 constitutes an indirect mounting portion.

The direction in which the main frame 3 and the engine bracket 5 are fastened by the bolts 34a is orthogonal to the directions in which the main frame 3 and the engine bracket 5 are fastened to the engine 13 by the fastening members 16 to 18. .

It should be noted that, as shown in FIG.
Supports a handle shaft 40 rotatably, supports a handle 41 on an upper portion thereof, and a bottom bridge 4 on a lower portion thereof.
A front wheel 44 is supported via a pair of left and right front forks 43 attached to the front wheel 2. Reference numeral 45 is a radiator,
46 is a front cowl, 47 is a seat, 48 is a side box, and 49 is a rear cover.

Next, the operation of the present embodiment will be described. FIG.
As apparent from FIGS. 3 and 3, when the casting frame 1 is fastened to the engine 13 at the direct mounting portion by the fastening member 17 and at the indirect mounting portion by the same 17 and 18 with the separate engine bracket 5 interposed therebetween, the vehicle body frame The rigidity balance in the whole can be appropriately maintained.

Further, since the molding distortion of the casting frame 1 can be absorbed by the interposition of the separate engine bracket 5, the casting frame 1 can be fastened to the engine 13. In addition, the quality of the casting frame 1 is stabilized, and the number of working steps can be reduced.

Further, since the direct mounting portion has a joint fastening structure of the casting frame 1 and the engine bracket 5, the number of fastening points can be reduced and the fastening rigidity can be easily secured.

In addition, the fastening direction of the bolt 34a, which is the fastening direction of the casting frame 1 and the engine bracket 5, is
Since the fastening directions of the fastening members 16 to 18 which are the fastening directions for the respective engines 13 are orthogonal to each other, the rigidity of the engine bracket 5 is increased, and the rigidity balance is further improved.

Furthermore, this casting frame 1 is
Since the upper and lower dies (not shown) can be formed by simply aligning the upper and lower dies (not shown) from above and below along the center line C of the shaft hole 2a of the head pipe 2 shown in FIG. It will be easier.

Further, since the substantially dish-shaped portion 4 is cast integrally with the main frame 3, the rigidity of the entire casting frame 1 can be increased by the substantially dish-shaped portion 4, and the rigidity is substantially the same as the conventional one. If you do, you can make the whole lighter,
In addition, since welding can be omitted, the weight of the entire body frame can be reduced as much as possible, and the number of manufacturing steps can be reduced.

In addition, the bottom portion 29 of the substantially dish-shaped portion 4
The suction port 29a, the discharge port 29b, and the drain port 29c of the air cleaner are opened, and the duct members (12, 11, 32) are directly attached to these openings. These duct members can be disposed by utilizing the above-mentioned structure, and since they are disposed in a portion that does not significantly affect the appearance, the degree of freedom in layout is increased.

It should be noted that the main frame 3 of the present invention does not necessarily directly support the engine 13, and such another embodiment will be described below. FIGS. 6 and 7 are views corresponding to FIGS. 1 and 2 according to this alternative embodiment, respectively.
However, since this embodiment is substantially the same as the previous embodiment except for a part, the same reference numerals are used for the common parts in the following description, and redundant description is omitted as much as possible.

In this embodiment, only the engine bracket 5 is attached to the engine 13 at the upper portion 35 of the fastening member 1.
6 and a nut 36, and a relief 21b (FIG. 6) is formed on the inner wall 21 of the main frame 3 at the fastening portion.

The main frame 3 is an engine bracket 5
And the step part 33 is fastened with the same structure as the previous embodiment. Therefore, the main frame 3 is fastened only to the engine bracket 5 and is not directly connected to the engine 13.

In this case, if the main frame 3 and the engine bracket 5 are jointly fastened to the engine 13, the rigidity of the fastening portion becomes too high, so that it is difficult to adopt the same structure as in the previous embodiment. Can be balanced.

[Brief description of the drawings]

FIG. 1 is an external side view of a casting frame according to the present invention.

FIG. 2 is a sectional view of the casting frame taken along line 2-2 of FIG. 3;

FIG. 3 is a sectional view of a vehicle body frame to which a lid is attached.

FIG. 4 is a plan view thereof.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is a view similar to FIG. 1 according to another embodiment;

FIG. 7 is a view similar to FIG. 2 according to the embodiment;

[Explanation of symbols]

1: Cast frame, 2: Head pipe, 3: Main frame, 4: Container part, 5: Engine bracket, 13:
Engine, 16, 17, 18: fastening members

Claims (3)

[Claims] 1. A motorcycle body frame for supporting an engine, comprising a head pipe for supporting a front wheel in a steerable manner and a main frame extending rearward from the head pipe, wherein the head pipe and the main frame are connected to each other. In addition to being formed as an integral casting frame by casting, an engine bracket to be fastened to the engine was provided in a substantially stepped manner and separately from the casting frame, and this engine bracket was fastened to a part of the casting frame at the step. A vehicle body frame structure for a motorcycle. 2. The motorcycle body frame structure according to claim 1, wherein said engine bracket and a part of said casting frame are fastened together to an engine. 3. The fastening direction between the main frame and the engine bracket is orthogonal to the fastening direction of the engine bracket to the engine.
Body structure of the motorcycle described in (1).