JP2676234B2 - Body frame of motorcycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle body frame of a motorcycle that is integrally formed by casting.

(Prior Art) Conventionally, a casting frame of this type has been disclosed in, for example, Japanese Patent Laid-Open No. 61-1293.
The one described in Japanese Patent No. 83 is known. This is a vehicle body frame comprising a head pipe portion and a body frame portion extending backward and downward in a U-shape from the head pipe portion,
The centerline of the vehicle body is divided into two parts symmetrically including the head pipe with the split surface as a split surface, and the two parts are cast and formed, and both are integrally connected by bolt connection, and various stays are attached.

(Problems to be Solved by the Invention) In the cast body frame, the front portion is bolted through a flange formed in the head pipe portion, and the rear portion is bolted through a cross member. Therefore, despite the cast molding, the number of man-hours in the assembling process such as the machining of these bolt holes, the attachment of cross members, and the attachment of various stays increases, which leads to a decrease in productivity, and the head pipe portion is also divided into two parts. As a result, the accuracy of the head pipe portion is difficult to obtain, and a patch or the like is required to maintain the strength, resulting in an increase in weight.

The present invention pays attention to the recent progress in casting technology and welding technology, considers the improvement of the accuracy and strength of the body frame in the split structure, achieves the weight reduction, and reduces the number of parts as much as possible. An object of the present invention is to provide a body frame of a motorcycle that improves productivity and achieves cost reduction.

(Means for Solving the Problem) As described in claim 1, the first means for solving the above-mentioned problem is to provide a head pipe part and a pair of left and right body frame parts extending rearward from the head pipe part. In the vehicle body frame of the motorcycle, the vehicle body frame is composed of divided frames divided by casting in the left-right direction, and one of the divided frames is a head pipe part at the front end of the main body frame part. Is a continuous casting structure, the other split frame is a casting structure having a split surface for connecting to the head pipe portion at the front end of the main body frame portion, and both split frames are integrally joined. It is a vehicle body frame of a motorcycle.

Also, the second means is as described in claim 2,
The cross member is integrally cast-molded on at least one of the divided frames according to claim 1,
A vehicle body frame of a motorcycle, wherein the cross member is joined to opposing split frame sides.

A third means is the casting structure according to claim 1, wherein the main body frame portion is a hollow body having a vertically long longitudinal section, and the left and right walls thereof are connected by a plurality of plate-shaped ribs. The vehicle body frame of the motorcycle, characterized in that

A fourth means is, as described in claim 4, in claim 3, wherein the rib has a bottom side at a portion connected to a wall on a vehicle body center side and a top side at a portion connected to an outer side wall. ,
A vehicle body frame of a motorcycle, characterized in that it has a substantially trapezoidal plate shape.

(Operation) According to the means of the first aspect, by joining the left and right divided frames, it is possible to obtain the vehicle body frame made of a cast body and in which the head pipe is not divided. Since the head pipe is not divided, the frame joint structure is simplified, the number of parts is small, and the weight is reduced.

According to the means of claim 2, in claim 1, the joining via the cross member is added to the joining of the left and right divided frames.

According to the third aspect of the present invention, in the first aspect, the main body frame portion is a hollow tube, but is reinforced by a plurality of plate-shaped ribs to increase rigidity.

According to the means of claim 4, in claim 3, the portion where the rib connects to the outer wall is the top side of the trapezoid,
Since the length is shorter than the bottom side, the sink mark generated during cooling during casting is small and the outer wall is formed smoothly.

(Embodiment) Referring to FIG. 1 to FIG. 5, reference numeral 1 denotes a vehicle body frame, and the vehicle body frame 1 has a head pipe portion 2 at a front portion and an inverted U-shape from a head pipe portion 2 to a lower rear portion. It is composed of an extending main body frame portion 3 and is cast into two parts on the right and left sides with the center line X of the vehicle body as a split surface 4.

The body frame 1 is a divided left frame 5
And the right frame 6 are made of light alloy that is divided into two parts on the left and right, and the split surface 4 is located in the center of the vehicle body behind the head pipe part 2 while avoiding the head pipe part 2 in the front part 1a. It is provided in a dogleg shape diagonally forward from the line X, and is provided on the center line X at the center of the first cross member 7 at the intermediate portion 1b and at the center of the second cross member 8 at the rear portion 1c. Four
To assemble the body frame 1 by welding.

The left and right frames 5 and 6 are provided with a plurality of engine mounts 9 which are engine stays on the lower side, a pair of seat frame mounting bosses 10 and 10 on the upper side, and the second lower frame.
Stand attachment holes 11 and 11 are formed in the cross member 8 respectively, and an opening 12 for a wire or a harness is formed in the left frame 5 on the left side of the head pipe portion 2.
A part of the first cross member 7 is solidly formed in the right frame 6 to form a mounting member hole 13 for a damper constituting a rear suspension.

Further, the main body frame portion 3 is formed in a hollow tubular shape having a vertically long cross section, and as shown in FIG. 5, a plurality of ribs 14 are provided inside the hollow portion to prevent plate noise, and
The shape of 14 is formed into a substantially trapezoidal shape in which the portion connected to the wall of the body frame portion 3 on the center side of the vehicle body is the bottom side and the portion connected to the outer side wall is the top side, and a so-called sink mark during casting is formed. The outer surface of the frame body has a smooth finish so as not to be generated on the outer wall.

Incidentally, as shown in FIG. 6, the split surface 4 of the front portion 1a of the vehicle body frame 1 may be formed in a straight line oblique to the center line X of the vehicle body.

According to the above configuration, the main body frame portion 3 is provided on the head pipe portion 2, both cross members 7, 8 and the engine mount 9.
The vehicle body frame 1 can be assembled by merely abutting and welding the left and right frames 5 and 6 which are integrally cast-molded with each other.

In addition, by incorporating the head pipe portion 2 that receives the most load and impact from the vehicle length direction into one of the frames 5,
Since the machining accuracy of the head pipe portion 2 can be easily obtained, and the split surface 4 in the front portion 1a of the vehicle body frame 1 is provided in a V shape avoiding the head pipe portion 2,
A shearing force due to the stress can be prevented from being applied along the split surface, and a reinforcing member such as a patch, which is capable of avoiding the stress concentration on the head pipe portion 2, is unnecessary, and the front of the vehicle body frame 1 is eliminated. The weight of the part can be reduced.

(Effect of the invention) As described above, according to the invention of claim 1, one divided frame in which the head pipe portion and the main body frame portion are integrally cast, and the other divided frame in which only the main body frame portion is cast, Since the vehicle body frame is formed only by joining the left and right members, the number of parts can be reduced, the joining work can be reduced, and the number of assembling steps can be reduced to achieve cost reduction. Further, by integrally casting the head pipe portion with one of the main body frame portions and assembling it into one of the divided frames, it is possible to improve the processing accuracy of the head pipe portion and reduce the weight of the front portion of the vehicle body frame.

Further, according to the invention of claim 2, by integrally casting including the cross member, it is possible to further reduce the number of parts and the cost.

According to the means of claim 3, since the main body frame portion is a vertically long hollow body, the strength against vertical loads is high,
The lateral ribs also improve the strength against lateral loads and torsional loads in addition to the vertical loads.

According to the means of claim 4, the length of the portion where the rib connects to the inner wall of the main body frame portion is large because it is the base of the trapezoid, so the connection strength is large and the rib rigidity is high. .
Further, since the short portion on the top side of the rib is connected to the outer side wall, it is difficult for the molten metal to be pulled by cooling the molten metal during casting, and the outer surface of the wall is kept smooth.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the first invention, FIG. 2 is a plan view of a front portion of a vehicle body frame, and FIG. 3 is III-I of FIG.
II sectional view, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along the line VV of FIG. 1, and FIG. 6 is a modification of the front split surface of the vehicle body frame. FIG. 1 …… Body frame 2 …… Head pipe part 3 …… Body frame part 4 …… Cleaving surface 5 …… Left frame (divided frame) 6 …… Right frame (divided frame) 7,8 …… Cross member 9 …… Engine mount X …… Center line

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 61-6084 (JP, A) JP 59-77991 (JP, A) JP 62-31576 (JP, A)

Claims (4)

(57) [Claims] 1. An automatic machine 2 comprising a head pipe part and a pair of left and right body frame parts extending rearward from the head pipe part.
In a vehicle body frame of a wheeled vehicle, the vehicle body frame is formed by casting and is divided into left and right divided frames, and one of the divided frames is integrally formed with a head pipe portion at the front end of the main body frame portion. A continuous casting structure, the other split frame is a casting structure having a split surface for connecting to the head pipe part at the front end of the main body frame part, and both split frames are integrally joined, Body frame of a motorcycle. 2. The automatic device according to claim 1, wherein a cross member is integrally cast-molded on at least one of the divided frames, and the cross member is joined to the opposing divided frame side. Body frame of a wheeled vehicle. 3. The casting structure according to claim 1, wherein the main body frame portion is a hollow body having a vertically long vertical cross section, and left and right walls thereof are connected by a plurality of plate-shaped ribs.
Body frame for motorcycles. 4. The plate according to claim 3, wherein the rib has a substantially trapezoidal plate shape having a bottom side as a portion connected to a wall on the center side of the vehicle body and a top side as a portion connected to an outer side wall. A characteristic body frame of a motorcycle.