JPH09193873A - Motorcycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine for a motorcycle which can be realize a compact engine and improve assembly and maintenance properties of a cooling pump. SOLUTION: When an engine for motorcycle provided with a cooling pump 23 for circulating cooling water, a self-starting motor 22 for start, and a balancer shaft 21 is constituted, the balancer shaft 21 is arranged in parallel with a crankshaft 7 below the crankshaft 7, and the cooling pump 23 and the self- starting motor 22 are arranged in such a manner that they form the same axis and are in parallel with the balancer shaft 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle engine, and more particularly to an improvement in the arrangement structure of a cooling pump, a starter motor and a balancer shaft.

[0002]

2. Description of the Related Art In an engine mounted on a motorcycle, engine components such as a starter cell motor, a balancer shaft, a cooling water circulation cooling pump, etc. must be compactly arranged in view of their applications. An example of such an arrangement structure has been proposed in Japanese Patent Laid-Open No. 5-231478. In this engine, a balancer shaft is arranged in front of the crankshaft, a cooling pump is arranged below the balancer shaft in parallel with the crankshaft, and a starter motor is arranged in parallel with the crankshaft below the crankcase behind the cooling pump. The structure is arranged in. Further, the pump cover having the discharge port of the cooling pump is arranged on the left side of the mating surface of the crankcase cover, that is, near the center of the crankcase width direction and facing the left side.

[0003]

However, in the arrangement structure of the above-mentioned conventional publication, since the cooling pump and the starter motor are arranged in parallel, the side view when the engine is viewed in the crankshaft direction becomes large, and it cannot be made compact. There is a problem. Further, in the conventional structure, since the pump cover is arranged closer to the center of the crankcase, there is a problem in that the cooling pump can be easily assembled from the side of the engine and maintainability is low.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object thereof is to provide a motorcycle engine in which engine components can be compactly arranged and the pump cover can be assembled and maintained easily. I am trying.

[0005]

According to a first aspect of the present invention, in a motorcycle engine including a cooling water circulation cooling pump, a starter cell motor, and a vibration isolation balancer shaft, the balancer shaft is provided below the crankshaft. It is characterized in that the cooling pump and the cell motor are arranged substantially parallel to each other on the front side of the front wall of the crankcase so as to be parallel to the crankshaft and parallel to the balancer shaft.

According to a second aspect of the present invention, in the first aspect, the cooling pump is arranged such that a pump cover having a suction port and a discharge port is located on the side opposite to the starter motor with respect to the pump body. The balancer shaft and the cooling pump are connected via an idler shaft provided therebetween.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are claims 1 and 2.
2 is a diagram for explaining a motorcycle engine according to an embodiment of the invention of FIG. 2, and FIG. 1 and FIG. 2 are a sectional side view and a sectional plan development view of the engine, respectively.

In the figure, reference numeral 1 is a motorcycle engine, and the engine 1 is a water-cooled two-cycle engine mounted on a vehicle body frame with the axis of the cylinder bore (cylinder axis) inclined about 35 degrees toward the front side of the vehicle body. In the engine 1, the cylinder body 3 is laminated on the upper mating surface of the crankcase 2, and the cylinder head 4 is laminated and fastened on the upper mating surface of the cylinder body 3, so that the piston 5 is slidable in the cylinder bore of the cylinder body 3. The piston 5 is inserted and connected to the crank pin 8 of the crank shaft 7 by the connecting rod 6. Further, a combustion recess 4a is provided in the lower mating surface of the cylinder head 4, and the recess 4a is provided.
The electrode of the spark plug 9 is exposed inside.

The inside of the crankcase 2 is divided by a partition wall 2c into a crank chamber 2a for accommodating the crank shaft 7 and a shift chamber 2b for accommodating the transmission mechanism 10. The crankshaft 7 has a boss portion 2e formed on the partition wall 2c.
Are rotatably supported by bearings 11a, 11a.

The transmission mechanism 10 rotates the change shaft 10c so that the main shaft 10a and the drive shaft 1 are rotated.
By changing the combination of transmission gears 0b, the engine speed is changed and transmitted to the rear wheels from the drive shaft 10b through a chain (not shown).

An exhaust port 12 communicating with the cylinder bore is formed in the front wall of the cylinder body 3, and an exhaust pipe 13 is connected to an external connection opening of the exhaust port 12. The cylinder body 3 has a crank chamber 2a.
And a plurality of scavenging ports 15 that communicate the inside of the cylinder bore
Are formed.

An intake opening 2d communicating with the crank chamber 2a is formed in the upper wall of the back surface (rear side) of the crankcase 2, and a reed valve 16 is inserted in the opening 2d. The reed valve 16 is of a single-open type having only a valve plate that opens upward. When the piston 5 rises, the crank chamber 2a automatically becomes negative pressure, and air is introduced. To prevent blowback of air. A carburetor 17 is connected to the upstream side of the reed valve 16 of the intake opening 2d, and an air cleaner is connected to the upstream side of the carburetor 17.

A centrifugal auto clutch 20 is mounted on the right end of the crankshaft 7 as seen in the traveling direction of the vehicle.
The output gear 20b of the output shaft 20a of the clutch 20 meshes with the input gear of the main shaft 10a of the speed change mechanism 10.

A balancer shaft 21 is arranged below the crank shaft 7 in parallel therewith. The balancer shaft 21 is axially supported by bearings 11b and 11b arranged on the boss portion 2e for the crank bearing 11a, and a pair of balance weights 21 are provided outside the bearings 11b and 11b.
a and 21b. The balance weight 21a,
Since 21b is located outside the boss 2e, the balance shaft 21 can be arranged close to the crankshaft 7 without causing the problem of interference between the balance weights 21a and 21b.

On the front side of the front wall 2f of the crankcase 2, a starting cell motor 22 is arranged so that its drive shaft 22a faces the left side of the vehicle body and is parallel to the crankshaft 7. The starter motor 22 is located at the center of the crankshaft 7 in the axial direction, and the drive gear 22b is always meshed with the ring gear 7a of the crankshaft 7 with the reduction gear group 24 interposed. The ring gear 7a is connected to the crankshaft 7 via a one-way clutch 7b. Therefore, for example, when the motor is rotated, the drive gear is moved in the axial direction so as to mesh with the ring gear (dive-in method). It is possible to reduce the axial distance between the gear 22a and the ring gear 7a, so that the starter motor 22 can be arranged to the left in the figure accordingly.

A cooling pump 23 is arranged on the right side of the starter motor 22. The cooling pump 23 is arranged such that the pump drive shaft 23a is substantially coaxial with the drive shaft 22a of the starter motor 22 and is parallel to the balancer shaft 21. A drive gear 26 is attached and fixed to the left end of the pump drive shaft 23a in the figure, and an impeller 23c is attached and fixed to the right end of the pump drive shaft 23a. The pump drive shaft 23a and the balancer shaft 21
An idler shaft 25 is arranged in parallel with the balancer shaft 21, and the drive gear 26 of the pump drive shaft 23a is disposed between the idler shaft 25 and the balancer shaft 21.
Engages with a drive gear 29 of the crankshaft 7 via an idler gear 27 and balancer gears 28a and 28b. The balancer gears 28a and 28b are the balancer shaft 21.
It is fitted with a spline.

The casing of the cooling pump 23 is a pump body 23b integrally formed with the crankcase cover.
And located on the right side of the pump main body 23b on the opposite side of the starter motor 22 from the discharge port 30a of the pump 23.
And a pump cover 30 having a suction port 30b. The pump cover 30 is detachably attached to the pump body 23b. Discharge port 30 of this pump cover 30
A cooling water hose 31 for sending the cooling water is connected to a, and a cooling water hose (not shown) for sucking the cooling water from the radiator is connected to the suction port 30b.

Next, the function and effect of this embodiment will be described. According to the present embodiment, the starter motor 22 and the cooling pump 23 are arranged on the front side of the front wall 2f of the crankcase 2, and both 22 and 23 are arranged substantially coaxially. Compared with this, the sand view of the engine can be made smaller and the engine can be made compact.

The pump cover 3 of the cooling pump 23 is also provided.
Since 0 is attached to the pump body 23b on the opposite side of the starter motor 22, that is, near the right side portion, the cooling pump 23 can be assembled and inspected and maintained from the right side of the vehicle to facilitate the assembly and maintenance work. Can be carried out and the workability can be improved.

Further, since the drive gear 22b of the starter motor 22 is connected to the crankshaft 7 via the ring gear 7a with a one-way clutch, the axial distance between the two gears 22b and 7a can be narrowed as compared with the so-called jump type. From this point, the starter motor 22 can be arranged closer to the outside (left side), and an arrangement space can be secured when the cooling pump 23 is coaxially arranged.

Furthermore, the rotation of the crankshaft 7 is arranged in parallel below the balancer shaft 21 and the idler shaft 2.
Since it is transmitted to the cooling pump 23 via 5,
A large space can be secured near the right end of the crankshaft 7, and the large-diameter centrifugal clutch 20 can be arranged without any trouble.

Further, since the balance weights 21a and 21b of the balancer shaft 21 are located on both outer sides of the crank chamber 2a in the axial direction, the balance weights 21a and 21b can be brought close to the crankshaft 7 while ensuring a rotation space. The engine can be made compact from this point as well.

[0023]

According to the invention of claim 1, the balancer shaft is arranged below the crankshaft in parallel with the crankshaft, and the cooling pump and the starter motor are substantially coaxial with the front side of the front wall of the crankcase. Since they are arranged, there is an effect that the engine size when viewed from the side can be reduced and the engine can be made compact.

According to the second aspect of the present invention, the pump cover of the cooling pump is arranged so as to be located on the opposite side of the pump body with respect to the pump body, and the cooling pump is connected to the balancer shaft via the idler shaft. This has the effect of improving the assembly and maintainability of the cooling pump while improving the efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional side view for explaining an engine for a motorcycle according to an embodiment of the present invention.

FIG. 2 is a sectional plan development view of the engine.

[Explanation of symbols]

 1 Water-cooled 2-cycle engine 2 Crankcase 2f Front wall 7 Crankshaft 21 Balancer shaft 22 Cell motor 23 Cooling pump 25 Idler shaft 30 Pump cover 30a Discharge port

Claims (2)

[Claims] 1. A motorcycle engine comprising a cooling water circulation cooling pump, a starting cell motor and a vibration isolation balancer shaft, wherein the balancer shaft is arranged below the crank shaft in parallel with the crank shaft, and An engine for a motorcycle, wherein the cooling pump and the starter motor are arranged on the front side of the front wall so as to be substantially coaxial with each other and parallel to the balancer shaft. 2. The cooling pump according to claim 1, wherein
A pump cover having a suction port and a discharge port is disposed on the opposite side of the pump body from the pump body, and the balancer shaft and the cooling pump are connected via an idler shaft interposed therebetween. A motorcycle engine characterized by being used.