JPH1191674A - Engine for autobicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen the exhaust system and improve mass concentration, and improve exhaust gas cooling performance by water-cooling in an engine for a single or multiple cylinder motor bicycle. SOLUTION: The length of a straight exhaust system from an exhaust port 24 is ensured by slanting a cylinder 3 to the back, attaching an exhaust manifold 13 to the front wall of a cylinder head 4, and connecting an exhaust pipe 14. Slanting the cylinder 3 to the back allows cooling water to be supplied to the exhaust port 24 from the inside of the cylinder head 4, and the exhaust gas is cooled by the cooling water ducts 32 in the exhaust manifold 13. Furthermore, a starter 19 or balancer is arranged in a space S3 created below the exhaust manifold 13 by slanting the cylinder to the back.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for a single-cylinder or parallel-cylinder motorcycle.

[0002]

2. Description of the Related Art FIG. 4 shows a motorcycle equipped with a conventional engine of this kind, and has an engine 1 having a plurality of parallel cylinders.
Is a crankcase 2 having a transmission case portion 2a in order from the bottom, a cylinder 3, a cylinder head 4,
A head cover 5 and the like are provided, and are supported by the frame 7. The center line C of the cylinder 3 is inclined forward at a constant angle θ1 with respect to a vertical line H passing through the crankshaft center O.
G1 indicates the position of the center of gravity of the actual motorcycle as a whole, and G2 indicates the position of the center of gravity of the engine alone.

FIG. 5 is an enlarged side view of the single engine shown in FIG. 4. An exhaust manifold 13 is provided at an exhaust outlet 24 formed on the front wall of the cylinder head 4 and faces forward and downward. Is connected to an exhaust pipe 14 for each cylinder. Each exhaust pipe 14 extends downward as shown in FIG. 4 and passes rearward below a lower side of the crankcase 2 to be connected to a silencer 15. .

In FIG. 5, a cooling water inlet 16 is provided at a lower portion of a front wall of the cylinder 3 and is connected to a cooling water pump 12 of a transmission case 2a via a cooling water hose 17. Further, a starter (starting motor) 19 is arranged at the rear end of the upper surface of the transmission case 2a.

[0005] In addition to the engine in which the cylinder is arranged in the forward inclination position as described above, there is also an engine in which the cylinder is arranged in the rear inclination position as disclosed in JP-A-63-145189. An exhaust outlet is formed on the rear wall of the cylinder head, and is connected to an exhaust system.

[0006]

The motorcycle equipped with the forward leaning type engine shown in FIGS. 4 and 5 has the following problems. (1) Due to the forward inclination type, the cylinder head 4 approaches the radiator 9 side in front and the space between the radiator 9 and the cylinder head 4 becomes narrower.
Is bent immediately downward from the exhaust outlet 24. For this reason, the length of the exhaust pipe 14 cannot be made long, and no improvement in torque at medium and low speeds can be expected.

(2) Even if water is sent to the exhaust system to cool the exhaust gas with water, the cooling water flows downward because the cylinder is tilted forward, and it is difficult to cool the exhaust system with water. . As a result, the back pressure in the exhaust pipe cannot be reduced.

(3) There is a space S1 as shown by oblique lines above the head cover 5, but in order to secure workability when performing maintenance on the components inside the head cover 5, the space S1 is required.
There is not much space for other parts on 1 and this is wasted space.

(4) The center of gravity G2 of the engine itself is located diagonally behind and behind the crankshaft center O as shown in FIG. 4 because the cylinder is in the forward leaning position, and the center of gravity of the entire actual vehicle when mounted on the actual vehicle The horizontal distance d1 from G1 is large.

[0010] Motorcycles equipped with the latter rearward tilting engine have the following problems. (1) Since the exhaust system is connected by providing an exhaust outlet on the rear wall of the cylinder head, the length of the exhaust system becomes very short.

(2) Since the exhaust pipe is disposed in the narrow space behind the cylinder head, the piping is complicated, and the mounting operation is difficult. In addition, since the exhaust system is disposed behind the cylinder head, the cooling effect of the exhaust gas by the traveling wind cannot be expected.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 of the present application is directed to a single-cylinder or parallel-multiple-cylinder motorcycle engine in which a cylinder is tilted rearward and a cylinder head is mounted. An exhaust manifold is provided on the front wall to connect the exhaust system.

According to a second aspect of the present invention, in the motorcycle engine according to the first aspect, a cooling water passage communicating with a cooling water outlet of a cylinder head is formed in the exhaust manifold. I have.

According to a third aspect of the present invention, in the motorcycle engine according to the second aspect, a starter or a balancer is disposed below the exhaust manifold.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a parallel 4 to which the present invention is applied.
It is a left side view of a motorcycle equipped with a cylinder engine,
Parts having the same names as those in FIG. 4 are denoted by the same reference numerals,
In the case of the same structure, the description is omitted. The frame 7 includes a front frame portion 7a extending rearward and downward from the head pipe 8, an intermediate frame portion 7b extending downward from the rear end of the front frame portion 7a, and a rear frame portion extending upward and rearward. 7c, the engine 1 is supported by the front frame portion 7a and the intermediate frame portion 7b via an appropriate mounting bracket or the like. A radiator 9 is disposed in front of the engine, and a fuel tank 10 is provided on the front frame portion 7a.
However, the sheet 11 is placed on the rear frame portion 7c.

Although only a part of the cowling 21 is shown by an imaginary line, the cowling 21 covers the front and right and left sides of the vehicle body.
A traveling wind intake opening (not shown) for taking traveling wind into the radiator 9 side is formed on a front surface that covers the front wheel 22.

The engine 1 includes, in order from the bottom, a crankcase 2 having a transmission case portion 2a, a cylinder (cylinder block) 3 having four cylinders, a cylinder head 4, and a head cover 5.
An oil pan 6 is provided below. G1 indicates the position of the center of gravity of the actual motorcycle, G2 indicates the position of the center of gravity of the engine alone, and its horizontal distance d2 is smaller than that of FIG. 4 because the cylinder 3 is tilted backward. It is getting shorter.

In FIG. 2 showing the engine alone, the crankcase 2, the cylinder 3 and the cylinder head 4 are connected by a common head bolt 25, and the cylinder 3
Is provided in an inclined posture in which its center line C is inclined rearward at a constant angle θ2 with respect to a vertical line H passing through the crankshaft center O. The inclination angle θ2 is preferably 30 ° to 40 °, and in such an angle range, the cylinder 3 and the transmission case portion 2a do not interfere with each other, and a wide space is secured on the front side of the cylinder 3 and the cylinder head 4. it can.

At the lower part of the rear wall of the cylinder 3, a cooling water inlet 1
6 is provided, and is connected via a cooling water hose 17 to a cooling water pump 12 provided on a side wall of the transmission case 2a. An exhaust outlet 24 is formed on the front wall of the cylinder head 4 and a cooling water outlet 26 is formed around the exhaust outlet. In the wall of the cylinder 3 and the wall of the cylinder head 4, a cooling water inlet 16 at the rear lower end is provided.
A cooling water passage is formed from the cooling water outlet 26 to the cooling water outlet 26 at the front upper end to cool water around the cylinder liner, around the combustion chamber, around the intake and exhaust holes in the head, and the like.

The cooling water outlet 26 is slightly upward,
An exhaust manifold 13 extending forward is provided on this mounting surface.
Are fastened by bolts 30 via gaskets or seals. The exhaust manifold 13 is slightly inclined forward with respect to the horizontal line. 29 is a screw boss formed on the exhaust outlet 24.

As shown in FIG. 3, the exhaust manifold 13 has an exhaust passage 31 for each cylinder and a cooling water passage 32 surrounding the exhaust passage 31. The exhaust manifold 13 projects upward from the front end upper wall. A cooling water outlet cylindrical portion 33 is formed.

In FIG. 2, an exhaust passage 31 penetrates to the front end of the exhaust manifold 13, and a cooling water passage 32 indicated by oblique lines communicates with the cooling water outlet 26 of the cylinder head 4 and extends to near the front end. Cooling water outlet tube 3
3 The cooling water outlet cylindrical portion 33 communicates with a thermostat 39 at the upper front through a connecting pipe 38.

The front end surface 40 of the exhaust manifold 13 is a slightly downwardly inclined surface, and the exhaust pipe 14 is connected to the front end inclined surface 40 by bolts 41.
Reference numeral 42 denotes a screw boss portion formed on the front end inclined surface 40.

In FIG. 1, an ignition coil 44 and an igniter 45 are disposed in a space S2 above the exhaust manifold 13, and the exhaust manifold 13
A starter 19 is disposed below the starter 19. The starter 19 is accommodated in a “F” -shaped space S 3 formed by the exhaust manifold 13 and the front wall of the cylinder 3, and is located behind the front end wall of the crankcase 2.

Each exhaust pipe 14 is connected to the exhaust manifold 1
3 extends downward between the radiator 9 and the engine 1 from the front end, bends rearward at a position lower than the crankcase 2, and passes rearward below the crankcase 2.
Near the position P1 in the middle of the passage, they are gathered into two gathering pipes, and near the rear lower end position P2 of the crankcase 2 are gathered into one gathering pipe. I have.

The cooling water outlet 48 of the radiator 9 is connected to the cooling water pump 12 via a cooling water pipe 49.

As for the length of the exhaust system, at least the length corresponding to the exhaust passage length A of the exhaust manifold 13 in FIG. 2 is longer than that of the conventional forward tilt type.

During traveling, traveling wind is taken in from the traveling wind intake opening of the cowling 21 shown in FIG. 1 to cool the radiator 9 and to operate the exhaust manifold 13 and the space S2 thereabove.
The ignition coil 44 and the igniter 45 are also cooled, and the starter 1
9 is also cooled.

The cooling water discharged from the radiator 9 is supplied into the cylinder 3 from the cooling water inlet 16 at the lower rear end of the cylinder by the cooling water pump 12 shown in FIG. After cooling to the vicinity of the exhaust hole and the like, the exhaust gas enters the cooling water passage 32 in the exhaust manifold 13 from the cooling water outlet 26 and cools the exhaust gas while flowing forward. At this time, since the exhaust manifold 13 is slightly upwardly inclined, the cooling water that has exchanged heat with the exhaust gas flows smoothly to the high front, and the cooling water outlet cylinder 33 at the front upper end connects to the thermostat 3.
It is returned to 9.

When the maintenance work inside the head cover 5 is performed, the head cover 5 can be exposed upward by, for example, removing the fuel tank 10, so that the head cover 5 is not obstructed by the ignition unit 44 or the ignition coil 45 or the like. Instead, the head cover 5 can be removed from the cylinder head 4 to check and repair each mechanism such as the intake / exhaust valve or the cam.

[0031]

[Other embodiments]

(1) The present invention can be applied to a single cylinder engine, a parallel two-cylinder engine, or a parallel three-cylinder engine. Of course, the present invention can be applied to an engine having five or more parallel cylinders.

(2) Although the embodiment of FIG. 1 has a structure in which the starter 19 is disposed in the lower space S3 of the exhaust manifold 13, a balancer may be disposed.

(3) The upper space S of the exhaust manifold 13
2 includes an ignition coil 44 and an igniter 4
In addition to 5, various electric components can be arranged.

[0034]

According to the first to third aspects of the present invention, (1) the cylinder 3 of the engine 1 is tilted rearward and the exhaust manifold 13 is provided on the front wall of the cylinder head 4; The exhaust outlet 24 of the cylinder head 4 moves rearward as compared with the tilt type. As a result, the length of the exhaust system, in particular, the length of a straight exhaust system forward from the exhaust outlet 24 of the cylinder head 4 can be increased, and the back pressure of the exhaust system can be reduced. Can be improved.

(2) By setting the cylinder 3 in the rearwardly inclined posture, a space S2 is formed above and in front of the cylinder head 4. Even if various components are disposed in the space S2, there is no problem in attaching and detaching the head cover 5. . That is, in the case of the conventional forward tilt type, a wasteful space is secured above the head cover in order to secure workability when performing maintenance on the components in the head cover. The space S2 formed above and in front of the head 4 can be effectively used for arranging various components. Moreover,
The various components arranged in the space S2 can be actively cooled using the traveling wind from the front.

(3) When the cylinder 3 is inclined backward, the center of gravity G2 of the engine alone moves rearward as shown in FIG. 1, so that the position of the center of gravity G1 of the entire vehicle when mounted on the actual vehicle is different from that of the entire vehicle. The horizontal distance d2 is reduced, and mass concentration can be achieved.

(4) By setting the cylinder 3 in the rearwardly inclined posture, the space on the front side of the cylinder head 4 is widened, and the exhaust system is arranged here, so that piping work is easy.

According to the second and third aspects of the present invention, since the cylinder 3 of the engine 1 is in the rearwardly inclined posture,
In the cylinder head 4, since the front surface on which the exhaust outlet 24 is formed faces upward and the exhaust outlet 24 moves to the uppermost end of the cylinder head 4, cooling after cooling the cylinder head 4 is performed. It is possible to smoothly feed water to the exhaust outlet 24, and in addition, since the cooling water passage 32 communicating with the cooling water outlet 26 of the cylinder head 4 is formed in the exhaust manifold 13, Exhaust gas immediately after exhaust can be sufficiently cooled with water, the exhaust pipe pressure (back pressure) can be reduced, and the torque at medium and low speeds can be further improved.

According to the third aspect of the present invention, the cylinder 3
When the starter 19 or the balancer is arranged in the space S3 formed below the exhaust manifold 13 by setting the rearwardly inclined posture, the space S3 can be effectively used for arranging parts and cooling by traveling wind. Can also be done.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle equipped with a parallel four-cylinder engine to which the present invention is applied.

FIG. 2 is a left side view of the engine alone of FIG. 1;

FIG. 3 is a rear view of the exhaust manifold (III-III in FIG. 2).
FIG.

FIG. 4 is a left side view of a motorcycle equipped with a conventional engine.

FIG. 5 is a left side view of the engine shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Crankcase 3 Cylinder 4 Cylinder head 13 Exhaust manifold 14 Exhaust pipe (exhaust system constituent member) 19 Starter 24 Exhaust outlet 26 Cooling water outlet 31 Exhaust passage 32 Cooling water passage 44 Ignition coil 45 Ignition

Claims (3)

[Claims] 1. An engine for a motorcycle having a single cylinder or a plurality of parallel cylinders, wherein a cylinder is inclined rearward and an exhaust manifold is provided on a front wall of a cylinder head to connect an exhaust system. Engine for motorcycles. 2. A cooling water outlet portion is formed in a front wall of a cylinder head, and a cooling water passage communicating with the cooling water outlet portion is formed in an exhaust manifold. Engine for motorcycles. 3. The motorcycle engine according to claim 2, wherein a starter or a balancer is disposed in a space formed below the exhaust manifold.