JPS6218393B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power unit consisting of an engine and a transmission for a motorcycle, and particularly relates to a power unit having a V-shaped cylinder arrangement with a crankshaft oriented left and right with respect to the direction of travel of the vehicle. .

A power unit with such a V-type cylinder arrangement has a large length in the longitudinal direction, and when it is mounted on a motorcycle, the center of gravity of the vehicle tends to move rearward. If this tendency becomes excessive, the load on the rear wheels of the vehicle becomes excessive, causing a phenomenon in which only the rear wheels wear significantly more than the front wheels, which is economically undesirable.

The object of the present invention is to optimize the loads borne by the front and rear wheels in order to eliminate such problems. The present invention will be explained below with reference to the illustrated embodiments. FIG. 1 is a side view of a motorcycle equipped with a power unit having a V-shaped cylinder arrangement. 1 in the diagram
2 is a front wheel, and 2 is a rear wheel. A power unit 4 is suspended from a vehicle frame 5 at an intermediate portion between the two wheels and located below a fuel tank 3. The power unit 4 has a total of four cylinders 7, two at the front and two at the rear across a vertical plane containing the axis C of the crankshaft 6.
8 is an exhaust pipe, and has a muffler 9 at its tail end. 1
Reference numeral 1 denotes an intake pipe which extends upward from the inside of the V-bank of the cylinders 7, 7, and extends into a recess 12 formed on the lower surface of the fuel tank 3.
It opens into the intake silencer box 13 inside. The intake silencer box 13 is further opened to the atmosphere via an air cleaner 14. Reference numeral 15 indicates a mixture generating device such as a carburetor. Therefore, the intake air is air cleaner 1.
4, it is inhaled, passed through, and reaches the sound deadening box 13.
From there, fuel is drawn into the intake pipe 11, and fuel is added to it by the air-fuel mixture generating means 15 to form a mixture, which is drawn into each cylinder 7, burned, and then exhausted through the exhaust pipe 8, and into the atmosphere through the muffler 9. is released.

The inside of the power unit 4 is as shown in FIG.
It consists of each cylinder 7, 7 and a unit case 16 connected to the lower surface thereof, and a crankshaft 6, a reduction shaft 17, a speed change shaft 18, 18, an output shaft 19, etc. are pivotally supported inside. Note that 21 is an intermediate shaft for converting the direction of rotational output. Unit case 16
Furthermore, an oil filter 22 is located in front of the oil filter 22.
and a cooling water pump 23 are arranged on the left and right, and a starter motor 24 is supported below. An oil pan 25 is provided on the lower surface of the center of the unit case 16 so as to protrude downward, and is further bent forward and extends below the oil filter 22 . Therefore, since these heavy parts are placed at the front of the unit case 16, the center of gravity of the power unit is kept relatively forward, and these parts, which tend to become hot, are cooled by the wind when the vehicle is running. .

A muffler 9 is provided on the lower surface of the unit case 16 behind the oil pan 25. As shown in FIG. 3, the muffler 9 has exhaust pipes 8 led from four cylinders 7 gathered together on the lower surface of the unit case 16, muffles the sound in a muffling chamber 9a forming an expansion and contraction chamber, and has a hollow tapered shape. It is discharged into the atmosphere from the exhaust pipe 9b. Therefore, the muffler 9 utilizes the space on the rear lower surface of the unit case 16 to accommodate a relatively heavy muffling chamber 9a, and guides the exhaust gas toward the rear of the vehicle through the hollow and lightweight exhaust pipe 9b. The center of gravity of the exhaust muffler 9 moves forward, and the large-capacity muffling chamber 9a is hidden by the unit case 16, so that the appearance is not spoiled.

As explained above, in a power unit having an engine with a V-shaped cylinder arrangement, the oil filter 22 and the cooling water pump 23 are arranged on the front surface of the unit case 16 extending rearward from the crankshaft 6, while Since the starting motor 24 is supported by the engine, and the oil pan 25 is projected downward from the center of the case 16 and bent further forward, the heavy object of the power unit itself is placed at the front.

Further, the silencer 9 also has a large weight silencing chamber 9a.
Since it is provided on the lower surface of the unit case, the center of gravity of the silencer 9 is also moved forward.

Thus, although the power unit 4 has a V-shaped cylinder arrangement, it has the advantage of being able to be installed without significantly moving the center of gravity of the vehicle rearward.

Note that the intake pipe 11 extends upward from the inside of the V bank, so it is guided rearward to the seat 2.
The center of gravity of the power unit 16 is kept forward compared to a power unit 16 that is connected to the air cleaner below the power unit 6.

[Brief explanation of the drawing]

FIG. 1 is a partial side view of a motorcycle equipped with a power unit according to the present invention, FIG. 2 is an enlarged sectional view of a main part of the power unit, and FIG. 3 is a partial sectional view showing an exhaust pipe. Figure 4 is a front view of the power unit.
FIG. 5 is a plan view thereof. 4... Power unit, 9... Silencer, 16...
Unit case, 24... Starting motor, 25...
Oil pan.

Claims (1)

[Claims] 1 Mounted on a motorcycle with the crankshaft arranged in the left-right direction, the cylinder has a V-shaped arrangement consisting of at least one cylinder inclined forward and one cylinder inclined backward with respect to the vertical plane containing the crankshaft, and the cylinder The oil filter and cooling water pump are placed on the front of the unit case that is connected to the bottom and extends rearward from there, while the starter motor is supported on the bottom surface of the oil pan, which protrudes from the center bottom of the unit case. A power unit that is bent forward from the top and extends below the oil filter and cooling water pump.