JPS6183473A - Crankcase of motorcycle - Google Patents

Abstract

PURPOSE:To reduce a lateral width in the bottom part of a crankcase and place an exhaust pipe in a high position without an increase of the total width of an engine, by coating both side surfaces of the crankcase with a cover in a connection surface tilting in the rear downward. CONSTITUTION:When both sides of a crankcase 7, connected with a cylinder 1 in its bottom, are coated with covers 8, the crankcase 7, setting an opening surface in its both sides to a connection surface 10 tilting to the inner toward the bottom, is coated with the cover 8 in said connection surface 10. The cover 8, providing in its bottom part a recess 9, arranges in this part an exhaust pipe 6b. In this way, an autobicycle, not protruding the exhaust pipe 6b to the outside from the total width of the crankcase 7, enables the minimum above- ground height Hb to be increased while a bank angle thetab to be spread.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) This invention relates to a crank case for a motorcycle that houses a crank, a transmission structure, and the like.

[Technical background of the invention and its problems]

The engine of a motorcycle is usually mounted in the center of the vehicle body, with one crankcase connected to the bottom of the cylinder.
It extends in the u direction and houses a crank, a 1-transmission mechanism, and the like. This crankcase is formed by casting, and is divided into several parts due to mold handling or the assembly of shafts and gears. What does it consist of?
There is 1 letter. On the other hand, the exhaust pipe is led out from the front side of the cylinder, extends downward, passes below the crankcase, and is guided rearward.

The arrangement is shown in FIG. The figure shows the engine from the rear. 1 shows the cylinders (multi-cylinder), 2 shows the intake port, 3 shows the crankcase alone, 4 shows the oil pan, and 5 shows the cover marked with na. The exhaust pipe 6 is arranged under both sides of the crankcase 3 and on both sides of the oil pan 4 in the most natural form.

As you can see from the above figure, the minimum ground height H is the exhaust fg;
It is determined by the (q position) of 6, so the engine cannot be lowered any further, and the seat height is also determined from the d3. In order to lower
If λ2 is placed in a position away from the crankcase 3 as shown in T; 5a, the engine IIJ will become longer and the bank angle θ may become smaller (θa), which is a problem. Also, as shown by the chain lines in the figure, it is conceivable to recess the lower bottom of both sides of the crankcase and place the exhaust pipe in this part, but since the open surface of the crankcase 3 is narrowed, the gli structure Post-processing or assembly becomes extremely difficult, or the case needs to be divided into smaller parts, resulting in serious problems in terms of productivity, accuracy, and cost.

(Objective of the Invention) The object of the present invention is to improve the above-mentioned problems and to increase the position of the exhaust pipe relative to the crankcase without significantly increasing the width of the engine or reducing productivity. This is to make it possible to do so.

[One degree requirement of the invention] In order to achieve the above object, the crankcase of the automatic two-wheeler I]i of the present invention is constructed by covering both sides with covers, with the joint of both covers facing downward. The crankcase is characterized by being set on an inclined surface that approaches inward, and the width of the lower part of the crankcase is shortened.

In this way, by arranging the exhaust pipes on both sides of the lower part of the crankcase, which has a reduced width, it is possible to increase the minimum height above ground without increasing the overall engine rlJ.

[Embodiments of the Invention] FIG. 2 explains the principle of this invention, and therefore shows the configuration as seen from the rear of the engine.

The open surfaces on both sides of the crankcase unit 7 extending below the cylinder 1 are set as mating surfaces 10 that are inclined downward and inward, and a cover 8 is attached to these mating surfaces. A recess 9 is provided in the lower part of the cover 8, and an exhaust pipe 6b is arranged in this part. As is clear from the figure, the exhaust pipe 6b does not protrude outward beyond the crankcase width, allowing the minimum ground clearance Hb to be increased (conversely, the engine can be lowered), and the bank angle θb
can be expanded. The l711 size of the crankcase unit 7 can be set as large as before, it can be manufactured using a simple type 1, and post-processing and shaft assembly are easy.

Embodiments of the present invention are shown in FIG. 3 and below.

FIG. 3 is a side view of the V-type engine crankcase with the cover removed, and the mating surface 10a for attaching the cover provided on the 17il radiation surface is inclined downwardly and inwardly.

11.12.13 is crankshaft, counter ll1111
, indicates the bearing hole of the drive shaft, , 14 is the mating surface 10a
This is a screw hole placed in the

4, 5, and 6 show a cover, in which a mating V surface 10b inclined downwardly and inwardly corresponding to the mating joint 10a is formed, and a port 1-insertion hole 15 is arranged. The crankcase is completed by separating the two parts 10a and 1Qb and tightening the screws passed through the holes 1-1Φ through holes 15 into the tapped holes 14. As not shown in FIG. 4, the exhaust pipe 6G is disposed in a recess 16 provided on the outside of the lower part of the cover.

The angle of inclination of the mating parts 10a and 10b is practically about 15 degrees so that the shearing force acting on the screw or dowel pin is not too large.

[Effects of the Invention] As mentioned above, the motorcycle crankcase according to the present invention
Alternatively, since the covers on both sides are attached at the mating surfaces that slope rearward and downward, the lower width of the crankcase can be reduced and the II trachea can be placed there, without increasing the size of the entire engine. The relative position of the exhaust pipe with respect to the crankcase can be made high, and the degree of freedom in designing the engine's minimum ground clearance, bank angle, seat height, etc. can be increased. Since the difficulty of post-processing and assembly is the same as before, the engine part can be made lighter and more compact without any cost increase, and the effect is to improve the performance and appearance of the motorcycle.J) real.

[Brief explanation of the drawing]

Fig. 1 is a rear view showing the arrangement of a conventional motorcycle engine part, Fig. 2 is a rear view of the engine part showing the basic structure of the crankcase of the present invention, and Fig. 3 is a rear view of the engine part showing an embodiment of the present invention. Figure 4 is a side view of the lower width of the crankcase shown, Figure 5 is a side view of the cover, and Figure 5 is a longitudinal cross-section taken in the direction of the △-A arrow in Figure 4.
¥:L view, FIG. 6 is a cross-sectional plan view taken along the line B-B in FIG. 4. 1... Cylinder, 6.5a, 6b, 5c... [Hunter, 7... Single crankcase, 8... Cover, 9
, 16... recess, 10a, 10b... mating surface. Applicant's agent Iriko Hatano-l Tsuhitsu 2 Deputy

Claims (1)

[Claims] In a crankcase configured with covers attached to both sides, the mating surfaces of both covers are set to be inclined surfaces where the bottom approaches inward, thereby shortening the width of the lower part of the crankcase. Two-wheeled vehicle crankcase.