JPH0144753Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial application field This invention provides a transmission device on one side of the engine, especially the crankshaft, and a timing transmission for driving the valve train camshaft on the other side. This invention relates to an operating noise reduction device for an engine in which a mechanism, an AC generator, and a cooling fan are arranged side by side from the inside.

(2) Prior Art Conventionally, in the above type of engine, a fan cover is provided to cover the outer periphery of the cooling fan, and a suction port is opened in the cover opposite to the suction portion of the cooling fan. There is.

(3) Problems to be solved by the invention By the way, in the above-mentioned conventional engine, when a timing transmission mechanism consisting of, for example, a sprocket and a chain is used, operating noise such as the meshing sound of the sprocket and chain is generated by the fan cover. There is a problem in that the air passes through the inlet and emanates to the outside, causing unpleasant noise. Therefore, in the past, AC
It is known that the generator side is a wet type to reduce the operating noise, but this method has another disadvantage of increasing power loss due to oil agitation, which causes a decrease in fuel efficiency. Another option is to use a silent chain for the timing transmission mechanism, but this requires a separate chain drive system to drive other auxiliary equipment such as the oil pump, making the overall structure complex and costly. This will cause another problem.

The present invention was developed in view of the above circumstances, and an object of the present invention is to provide an engine operating noise reduction device that can effectively reduce the noise from the timing transmission mechanism with an extremely simple structure. That is.

B. Structure of the invention (1) Means for solving the problem In order to achieve the above object, the invention provides a transmission device on one side of the crankshaft, and a timing adjustment device for driving the valve train camshaft on the other side. A transmission mechanism, an AC generator, and a cooling fan are arranged side by side in order from the inside, and a fan cover provided to cover the outer periphery of the cooling fan has a suction port opening opposite to the suction portion of the cooling fan. In this engine, a side cover is attached to the opening side of the crankcase located between the timing transmission mechanism and the AC generator, and a side cover is attached to the inside of the fan cover in cooperation with the side cover. A sound insulating cover is provided for suppressing the propagation of operating noise of the timing transmission mechanism toward the suction port, and this sound insulating cover covers a first portion surrounding the outer circumferential surface of the AC generator and a first portion surrounding the cooling and a second part interposed between the fan and the AC generator.

(2) Function The side cover and the sound insulating cover cooperate with each other to effectively suppress the operation noise of the timing transmission mechanism from being propagated to the cooling fan suction port side. It is possible to suppress the radiation from the suction port to the outside as much as possible.

In particular, the second part of the sound insulation cover, which is interposed between the cooling fan and the AC generator, prevents mud, water, etc. that entered with the air from the cooling fan suction port from adhering to the outside surface of the AC generator. prevent it from happening.

(3) Embodiment Hereinafter, an embodiment in which the device of the present invention is implemented in a scooter type motorcycle will be described with reference to the drawings.

In addition, in the following explanation, "left, right", "top, bottom"
refers to the direction of movement of the motorcycle.

In Fig. 1, a body frame F of a scooter-type motorcycle has a gooseneck-shaped rear frame 1.
It is equipped with a rear wheel W under this rear frame 1.
A power unit P for driving is provided. The front part of the power unit P is pivotally supported 3 on the front part of the rear frame 1 via an anti-vibration link 2, and the rear end is suspended on the upper part of the rear frame 1 via a rear suspension 4.

The power unit P is a four-cycle engine 5.
and a transmission part 6 connected thereto, and a carburetor 7 connected to the intake port of the engine 5 is located on the transmission part 6. The engine 5 is also covered by upper and lower shrouds 8 and 9 and a fan cover 10. The crankcase 11 of the engine 5 has left and right crankcase halves 11l, 11.
The left crankcase half 11l extends rearward, and its rear half constitutes a transmission case 12. The opening outer surfaces of the left crankcase half 11l and the transmission case 12 are covered with a synthetic resin transmission case cover 13, and the transmission case cover 13 is attached to the left crankcase half 11l by a plurality of bolts 14. Fixed.

The crankshaft 1 of the engine 5 is located in the transmission chamber C surrounded by the left crankcase half 11l, the transmission case 12, and the transmission case cover 13.
5 and a transmission shaft 16 rotatably supported by the transmission case 12, a conventionally known belt type continuously variable transmission T is provided. This continuously variable transmission T includes a drive-side variable diameter pulley 17 provided on the left end of the crankshaft 15, a driven-side variable diameter pulley 18 provided on the transmission shaft 16, and a drive-side variable diameter pulley 18 that is suspended between the two pulleys 17 and 18. It is composed of a V-belt 19. Further, a conventionally known starting clutch Cl is provided at the end of the transmission shaft 16 in parallel with the driven variable pulley 18. Furthermore, at the rear end of the transmission case 12,
An axle shaft 20 parallel to the transmission shaft 16 is rotatably supported, and the transmission shaft 16 and the axle shaft 20 are interlocked and connected via a conventionally known reduction gear mechanism 21. A rear wheel W is attached to the outer protruding end of the transmission case 12 of the axle 20.
is fixed.

The rotation of the crankshaft 15 of the engine 5 is transmitted to the rear wheels W via the continuously variable transmission T, the starting clutch Cl, and the reduction gear mechanism 21. Since the aforementioned transmission system is conventionally known, detailed explanation thereof will be omitted.

On the right side of the crankshaft 15 is a timing transmission mechanism for driving a valve train camshaft 22 on the upper part of the engine 5.
A Tr is provided, and an AC generator G is connected to the right end of the crankshaft 15.

The timing transmission mechanism Tr includes a drive sprocket 24 fixed to the crankshaft 15 as usual, and a driven sprocket 25 fixed to the valve drive camshaft 22.
and an endless timing chain 26 that is suspended between both sprockets 24 and 25, and the rotation of the crankshaft 15 is transmitted to the valve train camshaft 22 at a rotation ratio of 1/2 of the rotation of the crankshaft 15. communicated. Further, in the vicinity of the crankshaft 15, the crankcase 1
1 is an oil pump 2 consisting of a trochoid pump.
7 is provided, and the drive shaft 2 of this oil pump 27
A driving sprocket 29 is fixed to 8, and this sprocket 29 is connected to the timing transmission mechanism.
It is engaged with the back side of the timing chain 26 of the Tr and is driven by the timing chain 26.

A side cover 30 is fixed with bolts 31 to the open side surface of the right crankcase half 11r. The right end of the crankshaft 15 passes through the center of the side cover 30 via an oil seal 32, and the AC generator G is connected to the right end of the crankshaft 15 on the outside of the side cover 30.
are connected. Therefore, the side cover 30 partitions the timing transmission mechanism Tr and the AC generator G. The stator 33 of the AC generator G is fixed to the side cover 30 with bolts 34, and its rotor 35 is fixed to the end of the crankshaft 15. An engine cooling fan 36 projecting outward is fixed to the outer surface of the rotor 35 with screws 37. The outer periphery of AC generator G is
The sound insulating cover 38 is surrounded by a cylindrical portion 38a, and the outer end of the cylindrical portion 38a includes:
A flange-shaped portion 38b interposed between the outer end surface of the AC generator G and the cooling fan 36 is integrally provided. Furthermore, the outer periphery of the cooling fan 36 is covered with the fan cover 10 together with the AC generator G. Thus, the cylindrical portion 38a of the sound insulating cover 38 constitutes the first portion of the present invention, and the flange-shaped portion 38b constitutes the second portion of the present invention.

As shown in FIG. 5, the lower part of the fan cover 10 and the sound insulation cover 38 are connected to the side cover 30.
They are secured together by bolts 39. A suction port 40 is opened in the fan cover 10 so as to face the suction portion of the cooling fan 36, and a filter 41 is attached to the suction port 40.

In the figure, 42 is an ignition pulser, and 43 is a timing chain tensioner.

Next, the operation of the embodiment of the present invention will be explained.

Now, when the engine 5 is operated and the crankshaft 15 rotates, the rotation timing transmission mechanism Tr is activated.
The valve train camshaft 22 and the oil pump 27 are driven, and the AC generator G and the cooling fan 36 are also rotated. The rotation of the cooling fan 36 draws cold outside air into the fan cover 10 through the suction port 40, and the engine 5 can be forcibly air-cooled. In addition, the outside air sucked into the fan cover 10 is guided by the smooth outer surface of the sound insulating cover 38, flows with little resistance, and is guided to the heated portion of the engine 5, thereby effectively cooling the heated portion.

By the way, when the timing transmission mechanism Tr operates,
Operating noises such as driving and meshing noises between the driven sprockets 24 and 25 and the timing chain 26 are generated. In this case, if we consider a conventional system without the side cover 30 and the sound insulation cover 38, the operating noise bypasses the AC generator G and radiates to the outside through the suction port 40 of the cooling fan 36. This was a cause of noise generation, but in this embodiment, the side cover 30 and the sound insulation cover 38
This blocks the operating noise such as the meshing sound and makes it difficult for the operating noise to be transmitted to the suction port 40, so that it is possible to effectively prevent the operating noise from emanating to the outside through the suction port 40.

C. Effects of the invention As described above, according to the invention, a transmission device is provided on one side of the crankshaft, and a timing transmission mechanism for driving the valve train camshaft, an AC generator, and a cooling fan are installed on the other side from the inside. In an engine in which a suction port is opened facing the suction portion of the cooling fan, the fan cover, which is arranged in parallel and provided so as to cover the outer circumferential portion of the cooling fan, has the timing transmission mechanism and the AC
A side cover is attached to the opening side of the crankcase, which is located between the generator and the fan cover. A sound insulating cover is provided to suppress propagation to the mouth side, and the sound insulating cover surrounds the outer peripheral surface of the AC generator.
Since the second part is interposed between the cooling fan and the AC generator, the operation noise of the timing transmission mechanism is prevented from being propagated to the cooling fan suction port side by the side cover and the sound insulating cover. Therefore, it is possible to suppress the above-mentioned operating noise from being emitted from the cooling fan suction port to the outside as much as possible, and effectively reduce the generation of noise caused by the operating noise. can do. In particular, the second part of the sound insulation cover, which is interposed between the cooling fan and the AC generator, prevents mud, water, etc. that entered with the air from the cooling fan suction port from adhering to the outside surface of the AC generator. In addition, since the sound insulation cover is also used as a means to prevent mud, water, etc. from adhering to the AC generator, the structure of the device can be simplified and costs can be reduced. This is something that can contribute.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of a motorcycle equipped with an engine equipped with the device of the present invention, FIG. 2 is a view taken along the line shown in FIG.
4 is an enlarged sectional view taken along the line in FIG. 1, and FIG. 5 is an enlarged sectional view taken along the line shown in FIG. 1. G...AC generator, T...belt type continuously variable transmission as a transmission device, Tr...timing transmission mechanism, 10...fan cover, 11...crank case, 15...crankshaft, 22...valve drive camshaft, 30... side cover,
36...Cooling fan, 38...Sound insulation cover, 38a...
A cylindrical part as a first part, 38b... a flange-shaped part as a second part, 40... a suction port.

Claims (1)

[Scope of utility model registration request] A transmission device T is provided on one side of the crankshaft 15, and a timing transmission mechanism for driving the valve camshaft is provided on the other side.
Tr, AC generator G, and cooling fan 36 are arranged side by side in order from the inside, and a fan cover 10 provided to cover the outer circumference of the cooling fan 36 has a suction port opposite to the suction portion of the cooling fan 36. In the engine having an opening of 40, the timing transmission mechanism
A side cover 30 is attached to the opening side of the crankcase 11 located between the Tr and the AC generator G, and the timing control is provided inside the fan cover 10 in cooperation with the side cover 30. A sound insulating cover 38 is provided to suppress the propagation of the operating sound of the transmission mechanism Tr toward the suction port 40 side, and this sound insulating cover 38
The engine includes a first portion 38a surrounding the outer peripheral surface of the AC generator G, and a second portion 38b interposed between the cooling fan 36 and the AC generator G. Driving noise reduction device.