Motorcycle

Abstract: The invention increases the capacity of an engine intake system and the capacity of a housing box without raising a height of a seat. To achieve this, in a motorcycle (10), a crank case (52), an engine (16) extending a cylinder (54) forward from the crank case (52), and a housing box (21) are arranged under a seat (22). An intake passage (98) is extended rearward from the above of the cylinder (54), an intake port (96a) of the intake passage (98) is connected to an air chamber (47), and an intake port (47a) of the air chamber (47) is connected to an air cleaner (45) through a communication path (46). The air chamber (47) is arranged upward of the crank case (52). The housing box (21) is arranged rearward of the air chamber (47). The air cleaner (45) is arranged sideways of the housing box (21).

Description: SPECIFICATION The present invention relates to an arranging construction of an engine intake system and a housing box of a motorcycle. In some of motorcycles, an engine and a housing box are arranged under a seat as in a scooter type motorcycle. For the motorcycle of this kind, there has been known, for example, Japanese Patent No. 2525573 Publication "Air cleaner case for a scooter type vehicle" (hereinafter referred to as "prior art"). In the aforementioned prior art, as shown in FIG. 2 of the Publication thereof, an air cleaner case 29 is arranged at the rear of an engine body 25 (numeral is cited from those described in the Publication, and the same is true for the following), chambers 41 and 42 are arranged in front of the engine body 25, the chamber 42 is connected to the air cleaner case 29 through a connecting tube 37, the chamber 41 is provided integral with the chamber 42, and an intake port of the engine body 25 is connected to the chamber 41 through a carburetor 27. Further, in the aforementioned prior art, as shown in Fig. 1 of the publication, a power unit 13 having a power transmission device incorporated in the engine is mounted on a body frame 2 under a tandem seat 24 so as to be swung up and down. In the aforementioned prior art, preferably, the engine intake systems such as the air cleaner case 29 and the chambers 41 and 42 are of a relatively large capacity in order to sufficiently exhibit the performance of the engine body 25. Incidentally, in the scooter type motorcycle as in the aforementioned prior art, a housing box not shown is often arranged under the tandem seat 24. Preferably, the housing box is also large in housing capacity in term of a role. However, an arranging space under the seat is limited. When the large capacity engine intake systems and the large capacity housing box are arranged under the seat, the tandem seat 24 is unavoidably raised in order to secure the arranging space. The tandem seat 24 cannot be raised or lowered simply due to the foot-landing performance. EP 1 162 135 A2 as prior art in the sense of Art. 54(3) EPC, discloses an air cleaner and an air chamber connected by communication path to the side face of the air chamber. US 5 433 286 A discloses a motorcycle in accordance with the preamble of claim 1. There, no air chamber is provided between the engine and the air cleaner, and the air cleaner is disposed on the same side as the power transmission mechanism. JP 62 223 448 A discloses an air chamber between the engine and an air cleaner, but no housing box above the engine. It is therefore an object of the present invention to provide the technique capable of increasing the capacity of an engine intake system or the capacity of a housing box and the suspension stroke of the rear wheel without making a height of a seat higher. For achieving the aforementioned object, according to claim 1, there is provided a motorcycle in which a crank case, an engine with a cylinder extended forward from a crank case, a power transmission mechanism supporting a rear wheel and mounted to be swung up and down on one side of the motorcycle, and a housing box are arranged under a seat, wherein an intake passage is extended rearward from an upper part of said cylinder, and an air cleaner is arranged sideways of said housing box, characterized in that an air chamber arranged above said crank case is connected to an intake port of said intake passage, said housing box is arranged rearward of said air chamber, and said air cleaner and said air chamber are connected by a communication path to the rear side of the air chamber, wherein the air cleaner is disposed on the side of the motorcycle opposite the power transmission mechanism. The cylinder is extended forward from the crank case, a space above the crank case can be secured. The air chamber is arranged in this surplus space, the housing box is arranged in the surplus space rearward of the air chamber, and the air cleaner is arranged in the surplus space sideways of the housing box. Further, the surplus space above the cylinder is utilized to extend the intake passage rearward from the above of the cylinder, and the air chamber is connected to the intake port of the intake passage. And the air cleaner is connected to the air chamber by the communication path. As described above, the engine intake system comprising the air cleaner, the communication path, the air chamber and the intake passage, and the housing box can be arranged effectively making us of the surplus space under the seat. The present invention exhibits the following effect by the provision of the aforementioned structure. According to the claim 1, the cylinder is extended forward from the crank case whereby the air chamber is arranged in the space formed upward of the crank case, the housing box is arranged in the surplus space rearward of the air chamber, and the air cleaner is arranged in the surplus space sideways of the housing box, and in addition, the intake passage is extended rearward from the above of the cylinder making use of the surplus space upward of the cylinder, the air chamber is connected to the intake port of the intake passage, and the air cleaner is connected to the air chamber by the communication path. As described, the engine intake system comprising the air cleaner, the communication path, the air chamber and the intake passage and the housing box can be arranged making effective use of the surplus space under the seat. Therefore, the engine intake system and the housing box can be arranged at the optimum position so that they are not interfered with each other. Accordingly, the capacity of the engine intake system as well as the capacity of the housing box can be increased without raising the height of the seat. FIG. 1 is a left side view of a motorcycle according to the present invention. FIG. 2 is a left side view of an engine and a power transmission mechanism according to the present invention. FIG. 3 is a sectional view taken on line 3-3 of FIG. 2. FIG. 4 is a left side view of an engine and an intake system of an engine according to the present invention. FIG. 5 is a plan view of an intake system of an engine and a housing box according to the present invention. The embodiments of the present invention will be described hereinafter with reference to the accompanying drawings. With respect to "front", "rear", "left", "right", "upper" and "lower", Fr, Rr, L, R, and CL indicate front side, rear side, left side, right side, and body center (width center), respectively, in accordance with the direction as viewed from a rider. It is noted that the figures are to be viewed from the direction of reference characters. FIG. 1 is a left side view of a motorcycle according to the present invention. A motorcycle 10 is a scooter type motorcycle principally comprising: a body frame 11, a front fork 13 mounted on a head pipe 12 of the body frame 11, a front wheel 14 mounted on the front fork 13, a handlebar 15 connected of the front fork 13, an engine 16 mounted on the rear part of the body frame 11, a power transmission mechanism 17 mounted to be swung up and down on the engine 16, a rear wheel 18 mounted on the power transmission mechanism 17, a rear cushion unit 19 having a rear end of the power transmission mechanism 17 suspended on the body frame 11, a housing box 21 mounted on the rear upper part of the body frame 11, and a seat 22 arranged on the housing box 21 and mounted to be opened and closed. The seat 22 is a tandem seat. In the motorcycle 10, the body frame 11 is covered with a body cover 30. The body cover 30 comprises a front cover 31 covering the front part of the head pipe 12, an inner cover 32 covering the rear part of the front cover 31, left and right floor steps 33 on which feet of a rider are put, left and right floor skirts 34 extended downward from the outer edge of the floor steps 33, a center cover 35 extended rearward from the inner cover 32 to cover the longitudinal center of the body frame 11, and a rear cover 36 extended rearward from the center cover 35 to cover the rear part of the body frame 11. In the figure, numeral 37 indicates a handlebar cover; 38 a front fender; 39 a rear fender; 41 a window screen, 42 a radiator for cooling an engine; 43 a fuel tank; 44 a step for an occupant; 45 an air cleaner; 46 a connecting tube; 47 an air chamber; 48 an exhaust pipe for an engine; and 49 a muffler for exhaust, respectively. FIG. 2 is a left side view of the engine and the power transmission mechanism according to the present invention. The engine 16 is a 4-cycle 2-cylinder type water cooling engine having a cylinder 54 extended forward from a crank case 52. L1 indicates an axis of the cylinder 54. FIG. 3 is a sectional view taken on line 3-3 of FIG. 2. A case portion of the engine 16 comprises a crank case 52 having left and right case halves 51L and 51R connected by a bolt, a cylinder block 53 connected by a bolt to the front part of the crank case 52, left and right two cylinders 54 and 54 provided within the cylinder block 53, a cylinder head 55 connected by a bolt to the front part of the cylinder block 53, combustion chambers 56 and 56 formed in the cylinder head 55, a head cover 57 connected by a bolt to the front part of the cylinder head 55, and a valve gear chamber 58 formed between the cylinder head 55 and the head cover 57. Further, the engine 16 comprises a crank shaft 61 mounted rotatably on the crank case 52 and extended to left and right, cylinders 54 and 54 connected to the crank shaft 61 through connecting rods 62 and 62, pistons 63 and 63 which reciprocates within the cylinders 54 and 54, respectively, and a valve gear mechanism 64 housed in the valve gear chamber 58. A generator cover 66 is connected by a bolt to the right side part of the right case half body 51R to form a generator housing chamber 67 between the right case half body 51R and the generator cover 66 to house the generator 68 in the generator housing chamber 67. The generator 68 is connected to the right side part of the crank shaft 61. Since the generator cover 66 is secured to the crank case 52, the generator cover 66 is a part of the crank case 52, in the present invention. The power transmission mechanism 17 comprises a transmission mechanism case 72 having the front part mounted so as to be swung up and down on the left case half body 51L through a bearing 71 and extending rearward, a case cover 73 for closing a side opening of the transmission mechanism case 72, a transmission mechanism housing chamber 74 formed between the transmission mechanism case 72 and the case cover 73, and a transmission mechanism 75 housed in the transmission mechanism housing chamber 74. The transmission mechanism case 72 is formed with a boss part 76 projected on the width center side from the longitudinal halfway. The transmission mechanism 75 is a combined structure of a belt type variable transmission mechanism 75A connected to the crank shaft 61 and a gear mechanism 75B connected to the belt type variable transmission mechanism 75A, in which a rear wheel axle 77 is connected to the output side of the gear mechanism 75B, the rear wheel axle 77 being supported rotatably. Numeral 78 indicates a cover. On the other hand, the generator cover 66 has a front arm 81 mounted so as to be swung up and down. More specifically, a support shaft 82 is provided integrally on the front part of the front arm 81, and the support shaft 82 is supported rotatably on the generator cover 66 through a bearing 83. The front arm 81 extends rearward, a boss part 84 is projected on the width center side along the rear part of the crank case 52 from the rear end thereof, and the boss part 76 of the transmission mechanism case 72 is connected by bolts 85 and 85 to the boss part 84. Further, the front arm 81 has a rear arm 86 connected by a bolt 87. The rear arm 86 extends rearward, and the rear wheel axle 77 is supported rotatably by the rear end part thereof. The combined structure of the transmission mechanism case 72 and the front and rear arms 81 and 86 as described above forms a rear fork 88 having a generally H-shape as viewed from a plane. Accordingly, the front part of the rear fork 88 supporting the rear wheel 18 through the rear wheel axle 77 can be mounted so as to be swung up and down on the crank case 52. The rear fork 88 coincides a center P1 of the crank shaft 61 with a swing center P2. P3 indicates a center of the rear wheel axle 77. This figure further shows that on the rear end of the transmission mechanism case 72 and on the rear end of the rear arm 86 are provided brackets 89 and 89, respectively, for connecting lower parts of left and right rear cushion units 19 and 19. Hereupon, a description will be continued returning to FIG. 2 once. The cylinder head 55 has an intake port 92 provided with an intake valve 91 continuous to a combustion chamber 56 and an exhaust port 94 provided with an exhaust valve 93 continuous to the combustion chamber 56 formed integrally. When the engine 16 is viewed sideways, the intake port 92 is an upward opening, and the exhaust port 94 is a downward opening. An inlet pipe 95 connected to the intake port 92 extends rearward of the cylinder head 55, and a throttle valve 96 is connected to the rear end (upstream side) thereof. The upstream end of the throttle valve 96 is directed rearward. The inlet pipe 95 has a fuel injection device (injector) 97 for injecting fuel toward the intake valve 91 mounted thereon. The combined structure of the intake port 92, the inlet pipe 95 and the throttle valve 96 as described above forms an intake passage 98. In other words, the intake passage 98 is extended rearward from the above of the cylinder 54, and the intake port of the intake passage 98 is directed rearward. Numerals 59 and 59 indicate cam shafts of the valve gear mechanism 64. FIG. 4 is a left side view of the engine and the intake system of the engine showing that the engine 16 and the housing box 21 are arranged under the seat 22, and that the air chamber 47 is arranged upward of the crank case 52. The intake system 90 of the engine 16 (hereinafter referred to as "engine intake system 90") is that an intake port 47a of the air chamber 47 is connected to an outlet 45a of the air cleaner 45 through the connecting tube 46 as a communication path, and an upstream end 96a of the throttle valve 96, that is, an intake port of the intake passage 98 is connected to an outlet 47b of the air chamber 47 so as to introduce outside air into the combustion chambers 56 and 56 (see FIG. 2). FIG. 5 is a plan view of the intake system of the engine and the housing box according to the present invention showing that the housing box 21 is arranged at the rear of the air chamber 47, and the air cleaner 45 is arranged right sideways of the housing box 21. The air chamber 47 is an air chamber for evenly distributing air from the air cleaner 45 to the two combustion chambers 56 and 56 (see FIG. 3) through left and right two intake passages 98 and 98 branched. Air introduced from the air cleaner 45 by intake negative pressure of the engine enters the combustion chambers 56 and 56 of the engine 16 shown in FIG. 3 in the channel of the connecting tube 46 → air chamber 47 → throttle valves 96, 96 → inlet pipes 95, 95. The foregoing may be summarized as follows: The present invention is characterized in that as shown in FIGS. 4 and 5, (1) the cylinder 54 is extended forward from the crank case 52 to thereby provide the spaces above the crank case 52 and below the seat 22, and the air chamber 47 is arranged in the surplus space; (2) the housing box 21 is arranged in the surplus space rearward of the air chamber 47 and downward of the seat 22; (3) the air cleaner 45 is arranged in the surplus space sideways of the housing box 21 and downward of the seat 22; (4) the intake passage 98 is extended rearward from the above of the cylinder 54 making use of the surplus space formed upward of the cylinder 54 and downward of the seat 22, and the outlet 47b of the air chamber 47 is connected to the intake port 96a of the intake passage 98; and (5) as shown in FIG. 5, the air cleaner 45 and the air chamber 47 are connected by the connecting tube 46 taken around so as to make a detour the front corner of the housing box 21. In this manner, the housing box 21 and the engine intake system 90 can be arranged easily making effective use of the surplus space under the seat 22. Therefore, the housing box 21 and the engine intake system 90 can be arranged at the optimum position so that they are not interfered with each other. Accordingly, the capacity of the engine intake system 90 necessary for exhibiting the performance of the engine 16 can be increased sufficiently. Further, the capacity of the housing box 21 can be also increased. Moreover, the height of the seat 22 need not be raised. Getting on and off of occupants are facilitated by maintaining the height of the seat 22. It is noted in the above-described embodiment of the present invention that the motorcycle 10 is not limited to the scooter type motorcycle. Further, while in the above-described embodiment, the engine 16 is secured to the body frame 11 (vehicle body), the present invention can be also applied to a unit swing type motorcycle 10 (vehicle) in which the engine 16 and the power transmission mechanism 17 (power transmission system) are constituted integrally and supported on the body frame 11 so as to be swung up and down. The invention increases the capacity of an engine intake system and the capacity of a housing box without raising a height of a seat. To achieve this, in a motorcycle 10, a crank case 52, an engine 16 extending a cylinder 54 forward from the crank case 52, and a housing box 21 are arranged under a seat 22. An intake passage 98 is extended rearward from the above of the cylinder 54, an intake port 96a of the intake passage 98 is connected to an air chamber 47, and an intake port 47a of the air chamber 47 is connected to an air cleaner 45 through a communication path 46. The air chamber 47 is arranged upward of the crank case 52. The housing box 21 is arranged rearward of the air chamber 47. The air cleaner 45 is arranged sideways of the housing box 21.

Claims: A motorcycle in which a crank case (52), an engine (16) with a cylinder (54) extended forward from a crank case (52), a power transmission mechanism (17) supporting a rear wheel (18) and mounted to be swung up and down on one side of the motorcycle, and a housing box (21) are arranged under a seat (22), wherein an intake passage (98) is extended rearward from an upper part of said cylinder (54), and an air cleaner (45) is arranged sideways of said housing box (21), characterized in that an air chamber (47) arranged above said crank case (52) is connected to an intake port (47a) of said intake passage (98), said housing box (21) is arranged rearward of said air chamber (47), and said air cleaner (45) and said air chamber (47) are connected by a communication path (46) to the rear side of the air chamber (47), wherein the air cleaner (45) is disposed on the side of the motorcycle opposite the power transmission mechanism (17). Motorcycle according to claim 1, wherein said air chamber (47) is arranged in the middle of the motorcycle on both sides of a width center line (CL) of the motorcycle.

Inventors: KOJIMA MITSURU, MINAMI KASUTAKA, MORIYAMA YUICHI, KOJIMA, MITSURU, MINAMI, KASUTAKA, MORIYAMA, YUICHI, Kojima, Mitsuru, K.K. Honda Gijyutsu Kenkyusho, Minami, Kasutaka, K.K. Honda Gijyutsu Kenkyusho, Moriyama, Yuichi, K.K. Honda Gijyutsu Kenkyusho
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 2001
Main classification: F02M35
IPC codes: F02B61, F02B75, B62J1, F02B67, F02M35, B62J99