JP2593868B2 - Motorcycle frame structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motorcycle frame structure in which a frame and an engine are integrated to reduce the weight.

[Prior art and its problems] Generally, motorcycles are equipped with an engine on a rigid frame. In order to improve performance, the weight of the vehicle is reduced, and the frame is made lighter by using a light alloy. However, there is a limit to the weight reduction in the case where the engine is mounted on the frame. Particularly, in the case of a small-sized one, an engine in a frame is disclosed in JP-A-59-77991.
It is limited to small motorcycles and is not suitable for medium or larger vehicles.

Japanese Patent Application Laid-Open No. 62-59184 (prior art 1) and Japanese Patent Application Laid-Open No. 53-1 disclose a technique for increasing the rigidity of the body frame and reducing the weight by using the engine itself as a part of the frame.
No. 42739 (prior art 2) and JP-A-63-151592 (prior art 3).

However, in the prior art 1, since the down frame extends to the vicinity of the crankcase and the front frame extends to the transmission case, the frame length becomes longer and there is room for further improvement in terms of rigidity. Further, in the prior art 2, since the frame is mounted on the engine and the gearbox, there is a problem in terms of rigidity and difficulty in mounting. Further, in the prior arts 1 and 3, the engine is mounted on the frame from both sides of the engine block. When the engine has a large displacement and the left and right width of the multi-cylinder is large, the frame protrudes right and left. . A problem arises in that the slimness of the left and right width of the motorcycle is hindered.

[Object of the invention]

The present invention forms a frame integral with the engine by bisecting the frame back and forth and connecting it to the engine between them, thereby achieving a large weight reduction of the vehicle body and a reduction in manufacturing cost, and a rigidity. It is an object of the present invention to obtain a motorcycle frame structure in which the right and left width can be reduced even if the engine has a multi-cylinder engine.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a motorcycle in which a cylinder including a cylinder (2) and a cylinder head (3) is erected from a front portion of an engine case (1) to a front upper direction, and a front fork ( 13) A head pipe (4) with a steering hole (5) for attaching
H) and a front frame (4) formed integrally with a leg (6) extending left and right rearward and downward from the head pipe (4H), and together with the leg (4) of the front frame (4). The left and right widths of the lower end (6A) of 6) are formed substantially equal to the cylinder head (3), and the lower ends of the legs (6A, 6F, 6R) project from the upper and lower surfaces of the cylinder head (3). Department (3
F, 3R), and further, a rear frame (8) having left and right vertical frames (9) separate from the front frame (4) is vertically fastened to the left and right vertical frames (9). Part (11U,
11B), the upper and lower sides of the rear part (1R) of the engine case (1) are fastened and connected. A pivot (PC) for supporting the swing arm (14) is provided in the center of the vertical frame (9). 6A) Lower part (11) of front part (6F) and lower part of vertical frame (9)
B), and the axis passing through the rear end (6R) of the leg lower end (6A) and the upper fastening portion (11U) of the vertical frame (9) respectively (C,
B) and (H) in the center of the head pipe (4H)
C) and an axis (A) passing through the pivot (PC) is positioned so as to be sandwiched between the axes (C, B).

It should be noted that the front and rear legs (6) of the front frame (4) can be integrally formed with the front and rear direction air guide holes (15).

〔Example〕

 Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

1 to 4 show an embodiment of the present invention.

The motorcycle engine of the embodiment has an engine case 1
A transmission is built in the rear part of the engine case 1, and a cylinder composed of a cylinder 2 and a cylinder head 3 is erected from the front part of the engine case 1 to the front upper side, and is a type generally used for motorcycles. The engine is supported and fastened to the front frame 4.

The front frame 4 is integrally cast of a light alloy, and has a head pipe portion 4H having a steering hole 5 for attaching a front fork 13 at a front end thereof, and leg portions 6 extending left and right rearward and downward from the head pipe portion 4H. Are integrally formed. At the same time, the left and right widths of the lower end 6A of the leg 6 of the front frame 4 are formed substantially equal to the cylinder head 3, and the front and rear 6F and 6R of the lower end 6A of the leg 6 project from the front and rear of the upper surface of the cylinder head 3. Sections 3F and 3R are connected by bolts.

In this case, assembling accuracy is maintained by using the knock pin 7 as shown in FIG.

The rear frame 8 is separate from the front frame 4 and is formed by welding a rear pipe 10 made of a pipe to left and right vertical frames 9 formed by casting or the like with a light alloy.

The rear frame 8 is fastened and connected to the upper and lower portions of the rear portion 1R of the engine case 1 by upper and lower bolts 11U and 11B of the left and right vertical frames 9. A pivot PC for supporting a swing arm (rear hawk) 14 is provided at the center of the vertical frame 9. And
The leg lower end 6A, the front part 6F and the lower bolt 11 of the vertical frame 9
B, and the axis passing through the rear end 6R of the leg lower end 6A and the upper bolt 11U of the vertical frame 9 are denoted by C and B, respectively, the axis A passing through the center HC of the head pipe portion 4H and the pivot PC is the axis C , And B.

In this case, as shown in FIG. 4, the bolts 11U and 11B are formed with thick portions 12 and tightly fitted into the bolt holes to maintain assembly accuracy.

A front fork 13 is attached to the steering hole 5,
The wing arms 14 are attached to the left and right vertical frames 9.

5 and 6 show another embodiment of the present invention. In this case, the front and rear legs 6 of the front frame 4 are integrally provided with the air guide holes 15 of the front and rear method at the time of casting.
At 16 the front cowling 17 is connected so as to open to the front, and at the rear the hose 18 is connected and the air cleaner
Guide 19 near the inlet 20. Others are the same as those shown in FIGS. 1 to 4.

 Next, the operation of the embodiment will be described.

The frame is divided into a front frame 4 and a rear frame 8, and each is connected to the cylinder head 3 of the engine and the engine case 1 by bolts. Also, the front frame 4
Is easy to obtain accuracy because of integral molding by integral casting.
Also, the rigid engine case 1 and cylinder head 3
As a part of the frame, the upper pipe and the lower pipe of the frame can be omitted, the weight can be greatly reduced, and the cost can be reduced. Also, since the lower end 6A of the leg 6 of the front frame 4 is bolted to the mounting portions 3F and 3R projecting forward and backward of the cylinder head 3, a wide span for fixing the front frame 4 and the engine in the front-rear direction can be obtained. Therefore, the fixing (connection) rigidity is improved.

Further, since the left and right widths of the lower ends 6A of the leg portions 6 of the front frame 4 are formed substantially equal to the cylinder head 3, the body width can be reduced in the case of a multi-cylinder engine.

In addition, since the axis A passing through the center HC of the head pipe portion 4H and the pivot PC is located between the axes B and C, the front frame 4 has a lean size, and the front frame is downsized. The rigidity of the entire vehicle also contributes to improvement. That is, the swing arm is fixed and the head pipe 4H is twisted to check the torsional rigidity of the frame. Then, the torsion is centered on the axis A, but this axis A is the axis B,
Since it is sandwiched between C, the torsional force is applied to the sides of the axes B and C almost equally without any bias, and therefore, the rigidity of the entire vehicle body can be increased by supporting each of the fastening portions on the axis. It will improve.

Also, the accuracy of the connecting portion can be kept high by fitting the knock pin 7 and the thick portion 12 of the bolts 11U and 11B. Usually, frames made by pipe welding need to correct welding distortion, but this is not necessary.

In another embodiment shown in FIG. 5 and FIG. 6, the front and rear legs 6 of the front frame 4 are provided with front-rear direction ventilation holes 15 and hoses 16 and 18 are connected back and forth, so that the traveling wind is reduced. Can be guided to the air cleaner 19, so that absorption of hot air near the engine can be reduced, and the intake air temperature can be lowered.
Further, the air guide holes 15 can be formed at the time of casting the front frame 4 and can be inexpensive.

[Effects of the Invention] As described above, according to the present invention, since the front frame 4 is integrally formed by integral casting, accuracy can be easily obtained.
In addition, the rigid engine case 1 and the cylinder head become a part of the frame, so that the upper pipe and the lower pipe of the frame can be omitted, the weight can be reduced significantly, and the cost can be reduced. Also, the assembling accuracy can be increased, and there is no need to correct the shape as in a welding frame.

Also, since the lower ends of the legs of the front frame 4 are fastened to the mounting portions projecting forward and backward of the cylinder head with bolts or the like, the front frame 4 and the engine can be secured in a wide span in the front-rear direction. (Connection) rigidity is improved.

Further, since the left and right widths of the lower ends of the legs of the front frame 4 are formed substantially equal to the cylinder head 3, the width of the vehicle body can be reduced in the case of a multi-cylinder engine.

Further, since the axis A passing through the center HC of the head pipe portion 4H and the pivot PC is sandwiched between the axes B and C, the front frame 4 has a lean size and the front frame can be downsized. The overall rigidity also contributes to improvement. That is, the swing arm is fixed and the head pipe 4H is twisted to check the torsional rigidity of the frame. Then, the torsion is centered on the axis A, but this axis A is the axis B, C
, The torsional force is applied to both sides of the axis B and C almost equally without any bias, and therefore, the rigidity of the entire vehicle body is improved because it can be supported by the respective fastening parts on the axis. Is what you do.

Further, since the front frame 4 can be disassembled, the engine inspection and maintenance can be easily performed.

Also, by integrally forming the air guide holes on the left and right of the front frame legs, fresh air can be guided to the air cleaner, the absorption of hot air can be reduced, and the air guide holes are provided integrally with the front frame 4. It is inexpensive and can save space.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a side view, FIG. 2 is a plan view, FIG. 3 is a partially enlarged longitudinal sectional view of a front frame connecting portion, and FIG. The figure is an enlarged vertical sectional view of the rear frame connecting portion, FIGS. 5 and 6 show another embodiment of the present invention, FIG. 5 is a side view, and FIG. 6 is a plan view. 1 ... Engine case, 3 ... Cylinder head, 4 ...
... front frame, 5 ... steering hole, 6 ... legs, 8
…… Rear frame, 9 …… Vertical frame, 10 …… Rear pipe,
13 ... Front Hawk, 14 ... Swing Arm (Rear Hawk),
15 ... air vent.

Claims (2)

(57) [Claims] 1. A motorcycle in which a cylinder comprising a cylinder and a cylinder head is erected from a front part of an engine case to a front upper part, a head pipe part having a steering hole for attaching a front fork at a front end, and the head pipe part. A front frame integrally formed with legs extending left, right, rear and downward from the front frame, and the left and right widths of the lower ends of the legs of the front frame are formed substantially equal to the cylinder head. The rear frame having left and right vertical frames separate from the front frame is connected with the engine by the upper and lower fastening portions of the left and right vertical frames. Tighten and connect at the top and bottom of the rear part of the case, and provide a pivot for pivoting the swing arm at the center of the vertical frame. When the axes passing through the fastening portion, and the rear end of the lower end of the leg portion and the upper fastening portion of the vertical frame are respectively C and B, the axis A passing through the center of the head pipe portion and the pivot is the axis C and B. A motorcycle frame structure characterized by being sandwiched between the frames. 2. The motorcycle frame structure according to claim 1, wherein front and rear wind guide holes are integrally formed on both sides of the front frame.