JP2544909B2 - Air cleaner mounting structure for scooter type motorcycles - Google Patents

Description

The present invention relates to an air cleaner mounting structure for a scooter type motorcycle in which a forced air-cooled engine is housed in a rear cover.

[Conventional technology]

In this type of scooter-type motorcycle, a cooling air-blowing fan is attached to the crankshaft, and a forced air-cooling engine that blows the wind generated by this fan to the engine to cool it is used. It is generally housed in a rear cover that opens only downward. The shroud that covers the fan and the engine cylinder to form the air guide passage is formed so that the cooling air flows in the vehicle width direction. That is, after the cooling air taken in from one side of the vehicle body is made to flow across the cylinder, it is blown out from the opposite side surface of the vehicle body.

[Problems to be Solved by the Invention]

However, in such a structure, there is a problem that the air cleaner has to be arranged behind the engine and on the side of the rear wheel, and the capacity cannot be increased. This is because the accommodation space in the rear cover is narrowed at the rear part. That is, the rear cover is generally formed so that its cross-sectional shape becomes smaller toward the rear, and the cushion unit for suspending the rear wheels is housed in the rear portion, so that the air cleaner is arranged so as to avoid interference with these members. It is necessary to install it. In addition, the air cleaner may absorb the hot air after cooling the engine to reduce the intake efficiency of intake air, that is, the engine performance.

[Means for solving the problem]

The present invention has been made in view of the above circumstances, and provides an air cleaner mounting structure for a scooter type motorcycle in which the capacity of the air cleaner can be increased and hot air of heat that cools the engine is less likely to be sucked into the air cleaner. .

The scooter-type motorcycle air cleaner mounting structure according to the present invention has a low footrest between the handle and the seat, and covers the cooling air blower fan at the end of the cylinder and the crankshaft below the seat. A forced air-cooled engine having a shroud that forms a wind guide path and a cooling air blower fan in this engine extend rearward from a side opposite to the crankshaft direction and support a rear wheel at a rear end. And a swing type power unit in which the front portion is pivotally supported on the vehicle body frame and the rear end portion of the transmission case is connected to the vehicle body frame via a shock absorber, and is arranged downward from the lower edge of the seat. A rear cover, which extends backward to cover the upper periphery of the power unit and is continuous with the footrest, is formed in a rearward tapered shape in a plan view, and an air cleaner is arranged in the rear cover. In the cooter type motorcycle, the air cleaner has a structure that covers the cylinder over substantially the entire area when viewed from the side of the vehicle body, and is in close contact with a side surface of the shroud that is on the transmission case side of the downstream portion that covers the cylinder. The mouth is opened toward the inside of the vehicle body, and the intake opening and the exhaust opening of the shroud are opened on one side and the other side partitioned by the cylinder of the engine.

[Operation] In the present invention, the rear cover and the cushion unit are prevented from interfering with the air cleaner by accommodating the air cleaner in the front portion of the rear cover, which has a large cross-sectional shape. Further, the cylinder and the air cleaner are interposed between the intake port of the air cleaner and the exhaust port of the shroud.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.
FIG. 1 is a plan view showing a part of a motorcycle in which an air cleaner mounting structure for a scooter type motorcycle according to the present invention is implemented, FIG. 2 is a side view of the same, and FIG.
A cross-sectional view taken along the line I-III shown by reference numeral 1 in FIG. 2 shows a scooter type motorcycle. This motorcycle 1
Has a low-foot rest 4 between the handle 2 and the seat 3, and a rear cover 5 is provided at the rear of the rear cover 5, the upper part of which is closed by the seat 3 and which is opened substantially only downward.
Like the conventional one, the rear cover 5 is formed in a rearward tapered shape in a plan view so that the cross-sectional shape of the front part is relatively large and decreases toward the rear part. Further, the rear cover 5 is formed so as to extend downward from the lower edge of the seat to cover the upper periphery of a power unit described later and to be continuous with the footrest 4.

Reference numeral 10 denotes a forced air-cooled engine housed in the rear cover 5, which constitutes a swing-type power unit together with a transmission case 12 that houses a power transmission mechanism 11 that integrally extends from the side to the rear and transmits the engine power. In order to function as a component for suspending the rear wheel 13, the front portion of the body frame is connected via a pivot 14 and the rear end of the transmission case 12 is connected via a cushion unit 15 to the body frame. Is pivotally supported up and down. Further, the engine 10 is a crank chamber precompression type two-cycle engine, and a cylinder 20 is disposed in a substantially vertical direction immediately before the rear wheel 13. Reference numeral 21 denotes a crankshaft connected to a piston 23 via a connecting rod 22, and a shaft in the vehicle width direction via bearings 26, 26 press-fitted and fixed to cylindrical portions 25a, 25b formed integrally with a crankcase 24. It is hung. An exhaust pipe 27 extends obliquely downward from the front surface of the cylinder 20, extends rearward under the engine 10, and is supported below the rear cover 5 and to the side of the rear wheel 13. Connected to the muffler 28.

30 is a boss keyed to one end of the crankshaft 21
Reference numeral 31 denotes a cooling blower fan mounted together with the stator 32a of the generator 32, and 40 denotes a resin shroud that covers the outside of the cooling blower fan 30 and the outside of the cylinder 20 to form a cooling air guide passage. Is. The shroud 40 includes an upstream portion 40a that extends upward from the periphery of the cooling blower fan 30 to the side of the cylinder 20, and an outer portion of the cylinder 20 that extends from the upper portion of the upstream portion 40a in the vehicle width direction. Downstream part covering
It consists of 40b.

The upstream portion 40a has an air intake 41 at a portion facing the cooling blower fan 30. The downstream portion 40b is formed in a box shape that is opened downward, and an exhaust port 42 for blowing out cooling air is opened in the rear surface in the rear direction. The exhaust port 42 is oriented in a direction inclining slightly to the right and inclining downward so that the exhaust gas is blown toward the muffler 28.

Reference numeral 50 denotes an air cleaner having a substantially trapezoidal shape in a side view.The air cleaner 50 faces the cylinder 20 of the engine 10 on the side of the cylinder on the same side as the transmission case 12 and on the side surface of the cylinder 20 in the left-right direction of the vehicle body. As shown in FIG. 1, the shroud 40b is in close contact with the side surface of the downstream portion 40b on the transmission case 12 side. The air cleaner 50 includes a cleaner main body 50a opened leftward and a cover 50b that covers the outside of the cleaner main body 50a, extends in the front-rear direction on the transmission case 12, and is longer in the front-rear direction than the downstream portion 40b. Has been formed.
As shown in FIG. 2, the air cleaner 50 has a structure that covers the cylinder 20 over substantially the entire area when viewed from the side of the vehicle body.

Reference numeral 51 is an intake duct integrally formed in the front part of the cleaner body 50a. The intake duct extends forward of the downstream part 40b and the intake port 52 is opened toward the inside of the vehicle body. On the other hand, the rear portion extends rearward from the downstream portion 40b, and the air outlet 53 is opened on the inner side surface of the cleaner body 50a. Although not shown, a filter element that traps dust in the air is installed inside so as to define an internal space into two chambers.

60 is the air outlet 53 and the crankcase 24 of the engine 10.
It is a carburetor interposed in the middle of an intake passage communicating with the inside, and jets fuel into the air taken into the engine 10 to mix it.

In the air cleaner mounting structure for the scooter type motorcycle thus configured, when the engine 10 is started, intake air is drawn from the intake duct 51 having the intake port 52 opening inward as shown by an arrow A. After flowing into the air cleaner 50 and mixing the fuel in the carburetor 60, the engine 10
Inhaled. At this time, rainwater, mud,
Since it is difficult for dust and the like to enter, these foreign substances are rarely sucked into the air cleaner 50 from the intake port 52. Moreover, since the intake port 52 is opened so as to face the inside of the vehicle body, the dynamic pressure of the traveling wind flowing from the front side to the rear side of the vehicle body during traveling is the intake port 52.
Stable engine performance is obtained because it does not affect the engine.

On the other hand, the cooling air is taken in from the air intake 41 as shown by the arrow B, flows through the shroud 40 to cool the cylinder 20, and is then blown out backward from the exhaust 42. The engine-cooled hot air discharged from the shroud 40 is sucked into the air cleaner 50 because the cylinder 20 of the engine 10 and the air cleaner 50 are interposed between the exhaust port 42 and the intake port 52 of the air cleaner 50. There are few things. Therefore, the intake air can be delivered to the engine 10 with high intake efficiency.
Can be supplied to

The exhaust port 42 of the shroud 40 and the intake port 52 of the air cleaner 50 are arranged on one side and the other side of the cylinder 20.
The air cleaner 50 is designed so that hot air after cooling the engine 10 is not easily sucked into the intake port 52.
Can be disposed so as to face the side surface of the cylinder 20 on the transmission case side, and can be accommodated in the front portion of the rear cover 5, which has a large cross-sectional shape. Therefore,
The air cleaner 50 has a rear cover 5 and a cushion unit 15.
Since it is possible to suppress interference with the air cleaner 50 as compared with the conventional one, the capacity of the air cleaner 50 can be correspondingly increased.

In the above embodiment, an example in which the exhaust port 42 is opened on the rear surface of the downstream portion 40b has been described, but the present invention is not limited to this and may be opened on the front surface. In this case, by pointing in a direction different from the running direction,
The influence of running wind can be reduced. Further, the opening position of the intake port 52 of the air cleaner 50 is not limited to the front side of the cylinder 20 and can be changed as appropriate.

〔The invention's effect〕

As described above, the air cleaner mounting structure for the scooter type motorcycle according to the present invention has a structure in which the air cleaner covers the engine cylinder over substantially the entire area when viewed from the side of the vehicle body, and the cooling air for the cylinder and the crankshaft end is provided. Since the forced air-cooled engine shroud that covers the blower fan is in close contact with the side that is the transmission case side of the cylinder that covers the cylinder, the width of the rear cover gradually narrows toward the rear of the vehicle. Since the air cleaner is housed in the space on the front side of, the air cleaner can be prevented from interfering with the rear cover and the cushion unit, and the capacity of the air cleaner can be increased.

In a swing-type power unit with a forced air-cooled engine, a cylinder is positioned approximately in the center in the vehicle width direction, and the upstream part of the shroud that sends the air sucked in by a blower fan to the cylinder is arranged on one side of this cylinder in the crankshaft direction Therefore, when this power unit is covered with a rear cover, a dead space is a space on the side opposite to the upstream side of the shroud with respect to the cylinder and surrounded by the rear cover and the transmission case. Become.

According to the present invention, the air cleaner is arranged at the dead pace and is brought into close contact with the side surface of the downstream portion of the shroud.
The limited space in the rear cover can be effectively used, and the shroud and the air cleaner having a large volume can be compactly arranged in front of the inner space of the rear cover.

Thus, even if the shroud and the air cleaner are arranged side by side in the vehicle width direction and brought close to each other, the intake port of the air cleaner and the exhaust port of the shroud are opened on one side and the other side partitioned by the cylinder of the engine. Since the configuration is adopted, it is possible to prevent the cooling air discharged from the exhaust port, that is, the hot air after cooling the engine, from being sucked into the intake system from the air cleaner.
This is because the cylinder and the air cleaner are interposed between the intake port and the exhaust port. As described above, by preventing hot air from being sucked into the air cleaner, intake air can be supplied to the engine with high intake efficiency.
Enough engine performance can be secured.

Further, by adopting a configuration in which the side surface of the downstream portion of the shroud is covered by the air cleaner over substantially the entire area as viewed from the side of the vehicle body, an object that substantially functions as a sound insulation wall and is composed of an air cleaner is arranged on the side of the cylinder. Therefore, there is also an effect that the emission of engine noise generated in the cylinder can be reduced. Since the air cleaner can have a large capacity as described above, reduction of intake noise in a lower frequency range and improvement of engine output can be expected as compared with an engine equipped with an air cleaner having a small capacity.

Further, since the intake port of the air cleaner is opened toward the inside of the vehicle body, the air in the rear cover is sucked into the air cleaner when the engine is operated. That is, since it is difficult for rainwater, mud, dust, etc. to enter the inside of the rear cover, these foreign substances are less likely to be sucked into the air cleaner. Moreover, since the dynamic pressure of the traveling wind flowing from the front side to the rear side of the vehicle body during traveling rarely acts on the intake port,
Stable engine performance can be obtained.

In this way, the air in the rear cover is constantly sucked into the air cleaner, and the hot air after cooling the engine does not easily flow to the intake port side. It can prevent from staying.

Therefore, according to the present invention, it is possible to arrange the air cleaner on the side of the cylinder to increase the capacity and to improve the engine performance.

[Brief description of drawings]

FIG. 1 is a plan view showing a part of a motorcycle in which an air cleaner mounting structure for a scooter type motorcycle according to the present invention is implemented, FIG. 2 is a side view of the same, and FIG.
It is a sectional view taken along the line I-III. 5 ... rear cover, 10 ... engine, 20 ... cylinder,
40 …… Shroud, 40b …… Upper shroud, 42 …… Exhaust port, 50 …… Air cleaner, 51 …… Intake duct, 52 ……
Intake port, 60 ... Vaporizer.

Claims (1)

(57) [Claims] 1. A forced air-cooled engine having a low-floor footrest between a handle and a seat, and having a shroud below the seat, the shroud covering a cylinder and a cooling air blowing fan to form an air guide path. In this engine, a swing type power unit is integrally formed with a transmission case that extends rearward from a side opposite to the cooling air blower fan in the crankshaft direction and has a rear end supporting a rear wheel. And a rear end portion of the transmission case connected to the body frame via a shock absorber and extending downward from the lower edge of the seat to cover the upper periphery of the power unit and the footrest. In a scooter-type motorcycle having a rear cover that is tapered in a plan view and has an air cleaner arranged in the rear cover, the air cleaner is connected to the cylinder. The air cleaner has a structure that covers substantially the entire area when viewed from the side of the body, and is in close contact with the side surface on the transmission case side of the downstream portion that covers the cylinder in the shroud, and the intake port of this air cleaner is opened toward the inside of the vehicle body. An air cleaner mounting structure for a scooter type motorcycle, characterized in that an opening and an exhaust opening of the shroud are opened to one side and the other side partitioned by an engine cylinder.