JPS5847237Y2 - Cylinder block of side valve type internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a cylinder block used in a side valve type internal combustion engine.

Figure 1 shows a conventional example of this type of side-valve type air-cooled internal combustion engine, in which 1 is the cylinder, 2 is the crank chamber, 3 is the piston, 4 is the cylinder head, 5 is the intake valve, and 6 is the cylinder head. The exhaust valve, T is the crankshaft, 8 is the connecting rod, and 9 is the spark plug.

Normally, in the above-mentioned engine, the cylinder axis 10
and the valve axis lines 11° 12 of the intake valve 5 and exhaust valve 6 are parallel, and these axis lines 10 and 11° 12 are parallel to the cylinder 1.
It is perpendicular to the joint surface 13 with the cylinder head 4, and also forms a space 15 for passing cooling air between the cylinder 1 and the intake/exhaust valve shaft boss 14 in order to cool the cylinder 1. There is.

Therefore, the cylinder axis 10 and the valve axis 1 of the intake and exhaust valves
1.12 It is necessary to take a larger distance t by the amount to form the space 15.1 Furthermore, since the cylinder axis 10 and the valve axis 11.12 are parallel as described above, However, the shape of the combustion chamber 16 becomes flat, which causes problems such as deterioration of suction efficiency and the inability to obtain a large compression ratio, which impedes the ability to increase the output of the engine.

The present invention was developed in view of the above, and aims to improve engine performance by preventing flattening of the combustion chamber of an engine, and to reduce the size of the engine.

For this reason, the present invention makes the valve axis lines of the intake valve and the exhaust valve perpendicular to the joint surface of the cylinder with the cylinder head, and also makes the cylinder axis center line with respect to the valve axis line, between the two axis center lines. It is characterized by being inclined at a constant angle so that the distance decreases from the crankshaft side toward the joint surface side.

One embodiment of the present invention will be described below with reference to FIG. 2. 1 is a cylinder, 2 is a crank case, 3 is a piston,
4 is a cylinder head, 5 is an intake valve, 6 is an exhaust valve, I is a crankshaft, 8 is a connecting rod, 9 is a spark plug, 11 is an intake tappet, 18 is an exhaust pet, 19 is an intake cam, 20 is an exhaust cam It is.

The intake valve 5 and the exhaust valve 6 have their valve axis ill,
12 is disposed perpendicular to the upper surface of the cylinder 1, that is, the joint surface 13 with the cylinder head 4.

Further, the cylinder bore 1a is bored so that its N core line 10 is inclined by a certain angle θ with respect to the valve axis center line 11.12.

The direction of inclination of the axis 10 of the cylinder decreases as the distance between the axis 10 of the cylinder and the valve axis 11, 12 approaches the joint surface 13 from the crankshaft T side. is oriented so that the minimum t1 is reached at .

Note that the distance t1 is appropriately selected within a range where a space 15 for passing cooling air is formed between the cylinder and the valve shaft boss 14.

Further, the upper end edge of the cylinder bore 1a on the side of the intake and exhaust valves 5 and 6 is smoothly connected to the joint surface 13 at a curved surface 21.

The side valve type internal combustion engine equipped with the cylinder block described above is similar to the conventional one because the axis 10 of the cylinder 1 is inclined with respect to the valve axis 11, 12 of the intake valve 5 and exhaust valve 6. Although the space 15 for passing the cooling air is formed, the distance t1 between the two axes on the joint surface 13 is reduced compared to the conventional one, and therefore the combustion chamber 16
The width of the combustion chamber 16 in the t1 direction becomes smaller, and the combustion chamber 16 becomes closer to a spherical combustion chamber instead of becoming flat.

In the above-mentioned engine, when the piston 3 is at the top dead center (the position indicated by the chain line in FIG. 2), the wall area of the combustion chamber is smaller than that of the conventional engine, so a large compression ratio can be achieved.

Furthermore, since the curved surface 21 is provided on the cylinder bore 1a and the upper edge, the flow path resistance of the gas flowing between the upper combustion chamber 16a of the piston 3 and the intake valve 5 and exhaust valve 6 is reduced, especially the intake pressure. Losses are reduced.

In the above cylinder block, since the valve axis lines 11 and 12 of the intake and exhaust valves are perpendicular to the joint surface 13, the valve seats and tappet holes 22 of the intake valves 5 and exhaust valves 6 are machined to the same name. This can be done very easily just like the conventional method.

On the other hand, since the axis 10 of the cylinder is not perpendicular to the joint surface 13, the cylinder bore 1a must be bored in an oblique direction; however, the bore 1a is a single hole, and the valve seat and tappet hole 22 have the same name. The processing is easier than drilling in the diagonal direction, and it is relatively easy to perform the drilling in the same manner as in the conventional case where the drilling is perpendicular to the joint surface 13.

As described above, the cylinder block according to the present invention makes the valve axis lines of the intake valve and the exhaust valve perpendicular to the joint surface of the cylinder with the cylinder head, and the cylinder axis line is made to be perpendicular to the valve axis line. The distance between these axes is inclined at a certain angle so that it decreases as it approaches the joint surface from the crankshaft side, creating a space for cooling air to pass between the cylinder and the intake and exhaust valve shaft bosses. While maintaining this, the distance between the cylinder and the intake and exhaust valves can be narrowed compared to the conventional one, preventing the combustion chamber from becoming flattened and making it closer to a spherical combustion chamber.

Furthermore, since the wall area of the combustion chamber is reduced, the compression ratio of the engine can be increased.

Therefore, it is possible to improve the engine performance and to achieve high output of the engine.

Furthermore, the valve seats and tappet holes of the intake and exhaust valves, which are difficult to machine, are machined perpendicular to the joint surface, as with conventional ones, and the cylinder bores, which are relatively easy to machine, are machined in a direction perpendicular to the valve axis of the intake and exhaust valves. Since the machining is performed at an angle, the above effects can be achieved with almost the same number of machining steps as in the conventional method.

[Brief explanation of drawings]

FIG. 1 is a sectional view taken along the cylinder axis line showing an example of a conventional side valve type internal combustion engine, and FIG. 2 is a view corresponding to FIG. 1 showing an embodiment of the present invention. 1... Cylinder, 1a... Cylinder bore, 2... Crank case, 3... Piston, 4... Cylinder head, 5... ...
・Intake valve, 6...Exhaust valve, 10...Cylinder axis line, 11.12...Valve axis line of intake and exhaust valve, 13... ...Joint surface, 15...Cooling space.

Claims (1)

[Scope of utility model registration request] In a side-valve internal combustion engine in which an intake valve and an exhaust valve are arranged on the side of a cylinder, the valve axis lines of the intake valve and the exhaust valve are respectively perpendicular to the joint surface of the cylinder with the cylinder head, and A side valve characterized in that the axis of the cylinder is inclined at a certain angle with respect to the valve axis so that the distance between the two axes decreases as it approaches the joint surface from the crankshaft side. Cylinder flock of an internal combustion engine.