JPH022894Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for a water-cooled two-stroke internal combustion engine, which improves the cooling effect.

In conventional water-cooled two-stroke internal combustion engines, in order to arrange the scavenging passage, a water jacket is formed on the outer wall of the cylinder from almost above the scavenging passage to the cylinder head, and the cooling water is circulated so that the cylinder comes into direct contact with the combustion gas. The outer wall is cooled to reduce thermal distortion of the cylinder, and the temperature rise of fresh air flowing into the cylinder during the scavenging stroke is suppressed to improve the filling efficiency of fresh air.

However, in the conventional cooling structure described above, the outer wall of the scavenging passage only relies on air cooling and is not forcedly cooled, so the temperature of the outer wall of the scavenging passage fluctuates depending on various conditions such as engine speed and outside temperature. There was a problem where the fresh air temperature became unstable.

The present invention was developed in view of the above problems, and is a cooling system for a water-cooled two-stroke internal combustion engine that is equipped with a water pump and a radiator and circulates cooling water through a water jacket formed on the outer wall of the engine. A first water jacket is formed on the outer wall of the upper part of the cylinder, and a second water jacket is formed on the outer wall of the upper part of the cylinder, and the first and second water jackets communicate with each other through a communication path, and the first water jacket is connected to the water pump. In addition, by connecting the second water jacket to the radiator, the temperature of the intake fresh air passing through the scavenging passage is stabilized and lowered, increasing the efficiency with which intake air is filled into the cylinders and improving engine output. Water cooling type 2
The object of the present invention is to provide a cooling device for a cycle internal combustion engine.

Embodiments of the present invention will be described below based on the drawings.

1 and 3 show a two-stroke internal combustion engine according to the present invention, in which an engine body 1 is made up of a cylinder head 2, a cylinder block 3, and a crankcase 4 joined together. cylinder block 3
A cylinder sleeve 3a is fitted into the center hole to form a cylinder 3b, and an ignition plug 6 is screwed into the cylinder head 2, the tip of which faces the combustion chamber 5 above the cylinder 3b. A piston 7 is fitted into the cylinder 3b, and a piston pin (not shown) of the piston 7 and a crank pin (not shown) of a disc-shaped crank web 8a attached to a crankshaft 8 pivotally supported in the crankcase 4. (not shown) by a connecting rod 9, and the reciprocating motion of the piston 7 is converted into rotation of the crankshaft 8 via the connecting rod 9. An ACG rotor 10 is attached to the crankshaft 8. An intake passage 11 is opened in the crankcase 4 in a direction perpendicular to the crankshaft 8, and an exhaust passage 12 is located at a predetermined position above the cylinder 3b, spaced upward from the intake passage 11 and facing the intake passage 11.
is opened. A pair of scavenging passages 13 are formed in the outer wall of the cylinder block 3 and the crankcase 4 at positions facing each other in parallel with the crankshaft 8 of the cylinder 3b, communicating the crankcase 4 and a predetermined position above the cylinder 3b.

Above the scavenging passage 13, a first water jacket 14 is formed within the outer walls of the cylinder block 3 and cylinder head 2 at a position surrounding the cylinder 3a, as in the prior art. Furthermore, a second water jacket 15 is formed within the outer wall of the crankcase 4 at a position surrounding the scavenging passage 13. A communication passage 16 that communicates the first and second water jackets 14 and 15 with each other is formed in the outer walls of the crankcase 4 and the cylinder block 3, and the communication passage 16 also connects to the scavenging passage 13. It also serves as a water jacket. A water pump 18 driven by the crankshaft 8 via gears 17 that mesh with each other is disposed in the crankcase 4, and a discharge port 18a of the water pump 18 is connected to the cooling water inlet 15a of the second water jacket 15 and It is connected with a hose 19. On the other hand, the cooling water outlet 14a of the first water jacket 14 is connected to the inlet 21a of the radiator 21 through a water hose 20, and the outlet 21a of the radiator 21
b is connected to the suction port 18b of the water pump 18 through a water hose 22.

In addition, in the above, the first and second water jackets 14, 15 and the communication passage 16 are connected to the cylinder 3b.
The cooling water inlet 15a of the second water jacket 15 and the discharge port 18a of the water pump 18 and the cooling water inlet 15a of the second water jacket 15 may be formed so as to surround the entire circumference or partially surround the periphery. The water passage by the water hose 19 that connects the crankcase 4 may be formed integrally with the wall of the lower part of the crankcase 4 to cool the lower part of the crankcase 4.

In the above configuration, when the crankshaft 8 rotates when the engine 1 starts, and the water pump 18 is driven by the mutually meshing gears 17, the cooling water flows from the discharge port 18a through the water hose 19 to the second water jacket 15. Inflow. The cooling water flowing into the second water jacket 15 cools the scavenging passage 13 and the lower part of the side wall of the cylinder 3b, and then
The air cools the upper part of the scavenging passage 13 while ascending through the communication passage 16, and flows into the first water jacket 14 to cool the upper part of the cylinder 3b. The cooling water whose temperature has increased in this way is sent to the radiator 21 through the water hose 20, where it is cooled by heat exchange with the outside air, and then returned through the water hose 22 to the inlet port 18b of the water pump 18, and the above circulation is repeated. As a result, the intake fresh air is cooled by cooling water in the scavenging passage 13, and its temperature is stabilized and lowered.

As explained above, according to the present invention, in a cooling device for a water-cooled two-stroke internal combustion engine that includes a water pump and a radiator and circulates cooling water through a water jacket formed on the outer wall of the engine,
A first water jacket is formed on the outer wall of the scavenging passage of the engine, and a second water jacket is formed on the outer wall of the upper part of the cylinder, and the first and second water jackets communicate with each other through a communication passage. 1
Attach the water jacket to the water pump and
By connecting a water jacket to the radiator, fresh intake air is forcibly cooled by cooling water in the scavenging passage, so temperature fluctuations due to engine speed and outside temperature are suppressed, and the temperature is stabilized and lowered. , the cylinder filling efficiency is increased and the engine output is improved. Furthermore, since the distance between the water pump and the water jacket inlet is shortened, the piping is simplified.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view, FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIG. 3 is a cross-sectional view taken along the - line in FIG. . 1... Engine body, 14... First water jacket, 15... Second water jacket, 1
6...Communication path, 18...Water pump, 21...
...radiator.

Claims (1)

[Scope of utility model registration request] An engine body formed by integrally joining a cylinder head, a cylinder block, and a crankcase, a water pump, a radiator, a first water jacket formed within the outer walls of the cylinder head and cylinder block, and the cylinder block. and a scavenging passage formed in the outer wall of these across the crankcase, and in which cooling water is circulated through the water jacket. A second water jacket is formed within the outer wall of the crankcase, and the first and second water jackets communicate with each other through a communication passage formed across the crankcase and the cylinder block. A cooling device for a water-cooled two-stroke internal combustion engine, characterized in that a water jacket is connected to the radiator, and the second water jacket is connected to the water pump.