A vehicle comprising a sound insulation structure

Abstract

 The present invention relates to a vehicle (1) comprising a sound insulation structure (50) for a forced air cooling engine for motorcycle (1) which can attain both guidance of cooling air and sound insulation with one component without increasing the number of components. Here, a generally bowl-like sound insulation cover (50), which has a side peripheral wall (50a) surrounding an external peripheral part of an air suction port of an air shroud and an external side wall blocking a vehicle exterior side of the side peripheral wall, is attached to the vehicle exterior side of the air suction port (45a), openings of a generally oblong rectangular shape extending in a longitudinal direction of vehicle are formed in the external side wall, louvers (54) extending obliquely upward to an inner side in a crankshaft direction are formed at lower edges of the opening, and upper edges of the louvers (54) are located at a height substantially the same as that of upper edges of the openings.

Description

[0001] The present invention relates to a vehicle, in particular a motorcycle, comprising a sound insulation structure for a forced air cooling engine.

[0002] For example, in a scooter type motorcycle, a swing type engine unit including a forced air cooling engine and a V belt type continuously variable transmission may be mounted. In this type of forced air cooling engine, the circumference of a cylinder head including an external end of a crankshaft is surrounded by an air shroud substantially airtightly, an air suction port is formed in a part of the air shroud facing the external end of the crankshaft, and a cooling fan is attached to the external end of the crankshaft. Then, cooling air is sucked from the air suction port by the cooling fan to be forcibly supplied to the circumference of the cylinder head.

[0003] Incidentally, in the above-mentioned forced air cooling engine, since noises due to suction sound of the cooling fan at the time of normal drive including idling causes a problem, the noises are prevented from leaking to the outside of a vehicle as much as possible. Therefore, there have been proposed a forced air cooling engine with a structure in which an air suction port of an air shroud is covered by an external cover, see JP-B-6-29552, and a forced air cooling engine with a structure in which a suction port of an air shroud is covered by a cover to which a sound absorbing material is adhered, see JP-A-06-212995.

[0004] However, in the sound insulation structure described in the above-mentioned gazettes issued in the past, there is a problem in that the external cover or the cover serving as a sound barrier and an air guide (louver) for guiding the air into the air shroud are separate components, and the number of components is increased. In addition, there is a problem in that the number of components increases so much more for adhering the sound absorbing material to an inner surface of the cover.

[0005] The present invention has been devised in view of the above-mentioned circumstances, and it is an object of the present invention to provide a vehicle comprising a sound insulation structure for a forced air cooling engine, wherein the sound insulation structure is improved in cooling characteristic and production cost thereof.

[0006] The objective is solved according to the present invention by a vehicle, in particular a motorcycle, comprising a sound insulation structure for a forced air cooling engine, wherein said sound insulation structure comprises a sound insulation cover, and said sound insulation cover comprises wind introducing means at different side walls side walls thereof.

[0007] Preferred, said side walls are angled to each other.

[0008] According to a preferred embodiment, said wind introducing means are formed by a running wind introducing port and openings, wherein said running wind introducing port is arranged in a driving direction and said openings are arranged perpendicularly thereto.

[0009] Thus, said sound insulation structure can attain both the guiding of cooling air and the sound insulation with one component without increasing the number of components.

[0010] According to still a further preferred embodiment, said sound insulation cover is generally bowl-like, and said side walls consist of a side peripheral wall and of a cover-like external side wall, wherein said openings are provided on said cover-like external side wall.

[0011] According to another preferred embodiment, said openings are generally oblong rectangular-shaped and extend in a longitudinal direction of said sound insulation cover.

[0012] According to a further preferred embodiment, louvers extending obliquely upward to an inner side of said sound insulation cover are provided, wherein said louvers are formed at lower edges of said openings, and upper edges of said louvers are located at a height substantially the same as that of upper edges of said openings.

[0013] Thus, the engine is not visible by a view from above of the sound insulation cover and foreign bodies are prevented from entering the sound insulation cover.

[0014] According to another preferred embodiment, said side peripheral wall of said sound insulation cover is substantially parallel to a rear edge of a body cover of said vehicle, so that foreign bodies are also prevented from entering inside of the sound insulation cover.

[0015] According to a further preferred embodiment, a body frame of said vehicle is located in front of said running wind introducing port of said sound insulation cover.

[0016] According to a further preferred embodiment, an air shroud airtightly surrounds a cylinder block and a cylinder head and comprises a cooling air suction portion formed in a part of said air shroud and a cooling air discharge port formed in a part of said cylinder block, wherein said sound insulation cover covers said cooling air suction port of said air shroud.

[0017] According to a further preferred embodiment, a flat section for avoiding interference with an exhaust pipe is formed on a lower surface of said side peripheral wall of said sound insulation cover, so that the sound insulation cover is protected from damage through the heat of the exhaust pipe.

[0018] Preferred, the sound insulation cover is attached to the outside of the suction port of the air shroud, the rectangular openings extending in the longitudinal direction of the vehicle are formed on the external side wall of the sound insulation cover, the louvers extending obliquely upward to the inner side in the crankshaft direction are formed at the lower edges of the openings. Therefore, the cooling air is sucked into the air shroud from the openings along the louvers, and the cooling air can be sent to a cylinder section smoothly. On the other hand, since noises due to suction sound or the like of the cooling fan are discharged downward to the outside of the vehicle along the louvers after hitting the inner surface on the external side wall of the sound insulation cover, the noises can be discharged toward a direction in which the noises fades away from a rider and can be reduced. As a result, both the guidance of the cooling air and the reduction of noises can be achieved by one sound insulation cover without increasing the number of parts, and the sound absorbing material can be made unnecessary, whereby increase in cost can be controlled.

[0019] In addition, since the upper edges of the louvers are located at the height substantially the same as that of the upper edges of the openings, the openings can be substantially covered by the louvers, and the cooling fan in the sound insulation cover is never seen from upper and side positions of the vehicle, whereby deterioration of an appearance in the case in which the openings are formed on the external side wall of the sound insulation cover can be controlled.

[0020] Moreover, since the running wind introducing port, which is opened toward the front of the vehicle, is formed on the side peripheral wall of the sound insulation cover, cooling water during traveling can be introduced into the air shroud together with the cooling air from the openings of the external side wall, whereby a cooling efficiency of the engine can be improved. In addition, since fan noises from the running wind introducing port tend to be absorbed by running wind sucked from the running wind introducing port, noises can be reduced.

[0021] Additionally, since the running wind introducing port is opened in the body cover, and the peripheral edge of the running wind introducing port is formed so as to be in parallel with the rear edge of the body cover, the running wind introducing port is never seen from the sides of the vehicle, whereby deterioration of an appearance can be prevented. In addition, since fan noises are discharged into the body cover from the running wind introducing port, the fan noises are hardly heard from the outside, as a result, noises can be reduced and, moreover, suction sound of running wind can be prevented from leaking to the outside.

[0022] Furthermore, since the body frame is located in front of the running wind introducing port, a foreign body can be prevented from entering the sound insulation cover from the running wind introducing port without providing the specific shield.

[0023] Further preferred embodiments of the present invention are laid down in the further subclaims.

[0024] In the following, the present invention is explained in greater detail by means of several embodiments thereof in conjunction with the accompanying drawings, wherein:

Fig. 1

is a side view of a scooter type motorcycle mounted with a forced air cooling engine according to an embodiment of the present invention;

Fig. 2

is a sectional plan view of the forced air cooling engine;

Fig. 3

is a side view of a sound insulation cover mounted on the forced air cooling engine;

Fig. 4

is a rear view showing a mounting state of the sound insulation cover;

Fig. 5

is a bottom view showing the mounting state of the sound insulation cover;

Fig. 6

is a side view of the sound insulation cover;

Fig. 7

is a sectional view (sectional view along line VII-VII of Fig. 6) of the sound insulation cover; and

Fig. 8

is a sectional view (sectional view along line VIII-VIII of Fig. 6) of the sound insulation cover.

[0025] Figs. 1 to 8 are views for explaining a sound insulation structure for a forced air cooling engine according to one embodiment of the present invention. Fig. 1 is a side view of a scooter type motorcycle mounted with the forced air cooling engine, Fig. 2 is a sectional plan view of the forced air cooling engine, Figs. 3, 4, and 5 are a side view, a rear view, and a bottom view showing a mounting state of a sound insulation cover, respectively, Fig. 6 is a side view of the sound insulation cover, and Figs. 7 and 8 are sectional views (sectional views along line VII-VII and line VIII-VIII of Fig. 6) of the sound insulation cover.

[0026] In the figures, reference numeral 1 denotes a scooter type motorcycle, which is schematically of a structure in which a front fork 3 is supported pivotably to the left and right on a front end of an underbone type body frame 2 by a head pipe (not shown), a front wheel 4 is disposed at a lower end of the front fork 3, a steering handlebar 5 is disposed at an upper end thereof, a seat 6 is disposed in a central part in a longitudinal direction of the body frame 2, a swing type engine unit 7 is disposed under the seat 6 so as to be able to swing vertically, and a rear wheel 8 is disposed at a rear end of the engine unit 7.

[0027] A front side of the front fork 3 of the body frame 2 is surrounded by a front cover 9 and a rear side thereof is surrounded by a leg shield 10, and the steering handlebar 5 is surrounded by a handle cover 11. In addition, a foot board 12 on which rider's feed are placed is disposed at a lower end of the leg shield 10, and a lower part of the seat 6 is surrounded by left and right side covers 13.

[0028] The side covers 13 are divided into under covers 14 covering a lower side of the foot board 12 and upper covers 15 covering the lower part of the seat 6. Rear edges 13a of the side covers 13 rise obliquely upward from rear ends of the under covers 14 to central parts in the longitudinal direction of lower edges of the side covers 13.

[0029] The engine unit 7 is of a structure in which a V belt type continuously variable transmission 21 is integrally coupled to a left side part in a vehicle width direction of a forced air cooling engine 20.

[0030] This forced air cooling engine 20 is an engine of a two cycle single cylinder type and is of a structure in which a cylinder block 24 with plural cooling fins 24a integrally formed is coupled to a front side mating surface of a crank case 23 containing a crankshaft 22, which is arranged horizontally in the vehicle width direction and a cylinder head 25 is coupled to the cylinder block 24. A piston 27, which is coupled to the crankshaft 22 via a connecting rod 26, is slidably inserted and arranged in the cylinder block 24, and an ignition plug 28 is inserted in the cylinder head 25.

[0031] An exhaust port (not shown) is opened in a lower surface wall of the cylinder block 24, and an exhaust pipe 29 is connected to the exhaust port. This exhaust pipe 29 extends to the right side in the crankshaft direction through a lower side of the crank case 23 from the cylinder block 24 and extends in a rear direction of the vehicle from the right side end, and a muffler 29a, which is disposed on the right side of the rear wheel 8, is connected to the rear end.

[0032] A transmission case 30 extending to the rear of the vehicle is integrally formed on the left side part in the crankshaft direction of the crank case 23, and a case cover 31 is bolted and fixed to the vehicle exterior side of the transmission case 30. The -V belt type continuously variable transmission 21 is contained in a belt chamber formed by the transmission case 30 and the case cover 31.

[0033] This continuously variable transmission 21 is formed in a structure in which a V belt 36 is wound around a drive pulley 33, which is attached to a left side end of the crankshaft 22, and a driven pulley 35, which is attached to a transmission shaft 34 disposed in parallel with the crankshaft 22 at a rear end of the transmission case 30, and a centrifugal clutch 37 is attached to an outer side of the driven pulley 35 on the transmission shaft 34. In addition, a rear wheel drive shaft 41, to which the rear wheel 8 is adhered with the intervention of a deceleration mechanism 40, is disposed in parallel with the crankshaft 22 behind the transmission shaft 34. Further, rotation of the crankshaft 22 is constantly transmitted from the drive pulley 33 to the driven pulley 35 and, when the rotation of the crankshaft 22 increases, rotation of the driven pulley 35 is transmitted to the transmission shaft 34 via the centrifugal clutch 37 and is transmitted from the transmission shaft 34 to the rear wheel drive shaft 41 via the deceleration mechanism 40.

[0034] Next, the sound insulation structure of the above-mentioned forced air cooling engine 20 will be described.

[0035] An air shroud 45, which airtightly surrounds the cylinder block 24 and the cylinder head 25, is attached and fixed to a part extending from a right side end of the crankshaft 22 including the right side end to the cylinder block 24 and the cylinder head 25. A cooling air suction portion 45a is formed in a part of this air shroud 45 facing the right side end in the crankshaft direction, and a cooling air discharge port 45b is formed in a part of the cylinder block 24 facing the cooling fins 24a.

[0036] A generator 47 is mounted on the right side end of the crankshaft 22 so as to rotate together with the crankshaft 22, and a cooling fan 46 is formed on an external surface of the generator 47. When the cooling fan 46 rotates according to the rotation of the crankshaft 22, cooling air is sucked from the cooling air suction portion 45a, and this cooling air flows inside the air shroud 45 while cooling the cylinder block 24 and the cylinder head 25 and is discharged to the outside from the discharge port 45b (see arrow of Fig. 2).

[0037] A sound insulation cover 50 is disposed on the vehicle exterior side in the crankshaft direction of the cooling air suction port 45a of the air shroud 45. This sound insulation cover 50 is a substantially bowl-like cover constituted by integrally forming a side peripheral wall 50a, which is formed so as to airtightly surround an external peripheral part of the cooling air suction port 45a, and a cover-like external side wall 50b, which blocks the vehicle exterior side of the side peripheral wall 50a. Flange section 50c are formed at an opening edge of the side peripheral wall 50a. Each of these flange sections 50c is fastened and fixed to a boss section 45d of the air shroud 45 by a fixing screw 51.

[0038] A flat section 50d for avoiding interference with the exhaust pipe 29 is formed on a lower surface of the side peripheral wall 50a of the sound insulation cover 50. Consequently, the sound insulation cover 50 is prevented from being overheated by heat from the exhaust pipe 29.

[0039] A running wind introducing port 50e, which opens toward the front of the vehicle, is formed on the side peripheral wall 50a of the sound insulation cover 50. This running wind introducing port 50e inclines so as to define an angle of approximately 25 degrees with respect to a vertical line, and opens into the side covers 13. In addition, when viewed from the side of the vehicle, a peripheral part of the running wind introducing port 50e is in parallel with the rear edges 13a of the side covers 13.

[0040] In addition, a seat rail section 2a of the body frame 2 is arranged in front of the running wind introducing port 50e. Here, although not shown, the body frame 2 mainly includes an under pipe section extending from the head pipe in the lower rear direction, a foot rest section extending in the rear direction from a rear end of the under pipe section substantially horizontally, and the seat rail section 2a extending obliquely upward from a rear end of the foot rest section.

[0041] Four openings 52, 53 extending in the longitudinal direction of the vehicle are formed in parallel in the vertical direction on the external side wall 50b of the sound insulation cover 50. Among them, the upper three openings 52 are formed so as to generally have an oblong rectangular shape, and the opening 53 at the lowermost end is formed so as to generally have an arc shape.

[0042] At lower edges 52a of the respective rectangular openings 52, louvers 54, which extend obliquely upward to the inner side in the crankshaft direction, that is, into the sound insulation cover 50, are integrally formed. An inclination angle of the respective louvers 54 is set to generally 50 to 60 degrees. Moreover, upper edges 54a of the respective louvers 54 are set in a position of the same height as the upper edges 52b of the rectangular openings 52. Consequently, when viewed from upper and side positions outside the vehicle, the respective rectangular openings 52 are blocked by the louvers 54.

[0043] In addition, at a lower edge 53a of the arc-shaped opening 53, a louver 55, which extends vertically upward after extending in the rear direction from the lower edge 53a, is formed, and an upper edge 55a of the louver 55 is located at a height which is the same as that of the upper edge 53b of the arc-shaped opening 53.

[0044] Next, actions and advantages of this embodiment will be described.

[0045] During engine drive, the cooling fan 46 rotates in accordance with the rotation of the crankshaft 22 and, at the time of idling drive, cooling air is mainly sucked from the respective openings 52, 53 of the sound insulation cover 50. On the other hand, suction sound of the cooling fan 46 hits the inner surface of the louvers 54 and the inner surface of the external side wall 50b and is discharged downward to the outside of the vehicle from the rectangular openings 52 along the external surface of the louver 54 located on the lower side of the sound insulation cover 50.

[0046] At the time of traveling, the rotation of the cooling fan 46 increases as the rotation of the crankshaft 22 increases, whereby cooling air is sucked from the respective openings 52, 53 of the sound insulation cover 50 and, at the same time, running wind is sucked from the running wind introducing port 50e. In this case, noises of the running wind introducing port 50e are shut up in the sound insulation cover 50 by the cooling air sucked from the introducing port 50e, and discharge of the noises to the outside can be controlled.

[0047] In this way, according to the sound insulation structure of this embodiment, the bowl-like sound insulation cover 50 having the side peripheral wall 50a and the external side wall 50b is attached to the vehicle exterior side of the cooling air suction port 45a of the air shroud 45, the oblong rectangular openings 52 extending in the longitudinal direction of the vehicle are formed on the external side wall 50b of the sound insulation cover 50, and the louvers 54 extending obliquely upward into the sound insulation cover 50 are integrally formed at lower edges 52a of the respective rectangular openings 52. Therefore, cooling air is introduced into the sound insulation cover 50 from the respective openings 52 along the louvers 54, supplied to the cooling fins 24a of the cylinder head 24 through the air shroud 45, and discharged to the outside from the discharge port 45b after heat exchange is performed.

[0048] On the other hand, noises such as suction sound generated by the cooling fan 46 and engine sound hit the inner surfaces of the louvers 54 and the external side wall 50b of the sound insulation cover 50 and, then, are discharged downward to the outside of the vehicle from the openings 52 along the respective louvers 54, whereby the noises can be discharged toward the ground receding into the distance from the rider and can be reduced substantially. As a result, both the guidance of the cooling air and the reduction of noises can be achieved by one sound insulation cover 50 without increasing the number of components, and cost can be reduced compared with the conventional case in which two components are mounted.

[0049] In addition, since the upper edges 54a of the respective louvers 54 are located at the height substantially the same as that of the upper edges 52b of the rectangular openings 52, the openings 52 can be covered substantially by the louvers 54, and the cooling fan 46 in the sound insulation cover 50 is never seen from upper and side positions of the vehicle, whereby deterioration of an appearance caused by forming the openings 52 can be prevented.

[0050] In this embodiment, since the running wind introducing port 50e opening to the front of the vehicle is formed in the side peripheral wall 50a of the sound insulation cover 50, cooling air during traveling can be introduced into the air shroud 45 together with cooling air from the respective openings 52 of the external side wall 50b, and a cooling efficiency of the engine 20 can be improved.

[0051] In addition, fan noises or the like from the running wind introducing port 50e can be shut up in the sound insulation cover 50 by running wind sucked from the introducing port 50e, an effect of reducing noises can be improved.

[0052] In this embodiment, since the peripheral edge of the running wind introducing port 50e is formed so as to be parallel with the rear edges 13a of the side covers 13, and the running wind introducing port 50e is also opened into the side covers 13, the running wind introducing port 50e is never seen from the sides of the vehicle, whereby deterioration of an appearance can be prevented, and suction sound of running wind can be prevented from leaking to the outside.

[0053] In this embodiment, since the seat rail section 2a of the body frame 2 is arranged in front of the running wind introducing port 50e, a foreign body can be prevented from entering the sound insulation cover 50 from the running wind introducing port 50e without providing the specific shield.

[0054] Moreover, according to further embodiment, in a sound insulation structure for a forced air cooling engine for motorcycle an air suction port is formed in a part of an air shroud, which is formed so as to airtightly surround a cylinder portion including an external end of a crankshaft arranged toward a vehicle width direction, facing an external end of the crankshaft and a cooling fan is attached to the external end of the crankshaft, wherein a generally bowl-like sound insulation cover, which has a side peripheral wall surrounding an external peripheral part of the suction port and an external side wall blocking a vehicle exterior side of the side peripheral wall, is attached to the vehicle exterior side of the air suction port, openings of a generally oblong rectangular shape extending in a longitudinal direction of vehicle are formed in the external side wall, louvers extending obliquely upward to an inner side in a crankshaft direction are formed at lower edges of the openings, and upper edges of the louvers are located at a height substantially the same as that of upper edges of the openings.

[0055] Additionally, a running wind introducing port, which is opened toward the front of the vehicle, is formed in the side peripheral wall of the sound insulation cover.

[0056] Moreover, the running wind introducing port is opened in a body cover and, when viewed from the vehicle exterior side in the crankshaft direction, a peripheral edge of the running wind introducing port is formed so as to be in parallel with a rear edge of the body cover.

[0057] Finally, the body frame is located in front of the running wind introducing port of the sound insulation cover.

Claims

1. A vehicle, in particular a motorcycle, comprising a sound insulation structure for a forced air cooling engine (20), wherein said sound insulation structure comprises a sound insulation cover (50), and said sound insulation cover (50) comprises wind introducing means at different side walls side walls (50a,50b) thereof.

2. A vehicle according to claim 1, characterized in that said side walls (50a,50b) are angled to each other.

3. A vehicle according to claim 1 or 2, characterized in that said wind introducing means are formed by a running wind introducing port (50e) and openings (52,53), wherein said running wind introducing port (50e) is arranged in a driving direction and said openings (52,53) are arranged perpendicularly thereto.

4. A vehicle according to at least one of the claims 1 to 3, characterized in that said sound insulation cover (50) is generally bowl-like, and said side walls (50a,50b) consist of a side peripheral wall (50a) and of a cover-like external side wall (50b), wherein said openings (52,53) are provided on said cover-like external side wall (50b).

5. A vehicle according to claim 3 or 4, characterized in that said openings (52,53) are generally oblong rectangular-shaped and extend in a longitudinal direction of said sound insulation cover (50).

6. A vehicle according to at least one of the claims 3 to 5, characterized by louvers (54,55) extending obliquely upward to an inner side of said sound insulation cover (50), wherein said louvers (54,55) are formed at lower edges (52a,53a) of said openings (52,53), and upper edges (54a,55a) of said louvers (54,55) are located at a height substantially the same as that of upper edges (52b,53b) of said openings (52,53).

7. A vehicle according to at least one of the claims 4 to 6, characterized in that said side peripheral wall (50a) of said sound insulation cover (50) is substantially parallel to a rear edge (13a) of a body cover (13) of said vehicle.

8. A vehicle according to at least one of the claims 3 to 7, characterized in that a body frame (2) of said vehicle is located in front of said running wind introducing port (50e) of said sound insulation cover (50).

9. A vehicle according to at least one of the claims 1 to 8, characterized by an air shroud (45) airtightly surrounding a cylinder block (24) and a cylinder head (25), and comprising a cooling air suction portion (45a) formed in a part of said air shroud (45) and a cooling air discharge port (45b) formed in a part of said cylinder block (24), wherein said sound insulation cover (50) covers said cooling air suction port (45a) of said air shroud (45).

10. A vehicle according to at least one of the claims 4 to 9, characterized by a flat section (50d) for avoiding interference with an exhaust pipe (29) being formed on a lower surface of said side peripheral wall (50a) of said sound insulation cover (50).

Drawing