JPS5913319Y2 - cylinder block of internal combustion engine - Google Patents

Description

[Detailed description of the invention] This invention relates to cylinder blocks for diesel, gasoline, and gas internal combustion engines that have a press-fit dry cylinder liner, and prevents gaps between each part of the cylinder liner and the piston from becoming too large or too small. The purpose is to suppress lubricant consumption and blow μ・i, as well as prevent piston seizure.

1 is a vertical cross-sectional partial view of a conventional example of a vertical internal combustion engine.

This will be explained with reference to FIGS. 1 and 2. In the cylinder block having a press-fit dry cylinder liner, which is the subject of the present invention, an annular hollow part for the cooling water passage 2 is provided inside the cylinder block 1 as shown in Fig. 1, and a thin cylinder liner is provided on the entire inner cylindrical surface of the block 1. 3 is press fit.

A shock is applied to the lower end 5 of the liner 3 due to the fluttering (oscillation) of the piston 6 at bottom dead center, but the liner 3 has a small wall thickness and its own strength is low, so it cannot withstand the above shock. It is necessary to support the liner lower end 5 with the cylinder block 1.

Therefore, when block 1 is compared with block 1a having wet liner 3a of FIG. 2, cylinder liner 3a of FIG.
The length L of the liner supporting portion of the block 1 shown in FIG. 1 is increased compared to the case where the lower end portion 5a does not need to be supported by the block 1a due to its large wall thickness and strength.

In order to suppress the weight increase due to the increase in length L, the first
The cooling water channel 2 shown in the figure extends further downward than the cooling water channel 2a shown in FIG.

However, according to the structure shown in FIG. 1, the lower part 7 of the liner that is away from the combustion chamber 10 is cooled by the cooling water W to the same extent as the upper part 8 of the liner facing the combustion chamber 10, so the lower part 7 is supercooled and thermally expands. The amount becomes small, and the gap between the lower part 7 and the piston 6 becomes too small, which may cause seizure of the piston 6.

In addition, since the upper part 8 has a higher temperature than the lower part 7 and has a larger amount of thermal expansion, if the gap between the lower part 7 and the piston 6 is set large enough to prevent the above-mentioned seizure, the upper part 8 and the piston 6
If the gap between the two becomes too large, the lubricating oil in the crank chamber 11 will easily rise up into the combustion chamber 10 through the gap, resulting in an increase in lubricant consumption. In other words, the problem of blow-by occurs.

Moreover, since the amount of cooling water W increases, the warm-up time becomes longer, and in the case of a direct injection engine, the piston 6 is supercooled at low speed and low output at the start of operation, and the exhaust gas is exhausted due to poor combustion. Blue-white smoke and strange smells are generated inside.

In order to solve the above-mentioned conventional problems, the present invention forms an annular hollow part for the cooling water channel only in the thick-walled interior of the cylinder head side of the cylinder block, and the thick-walled part of the cylinder block adjacent to the above-mentioned hollow part on the crank chamber side. This is a device in which an annular or partially annular cavity into which no cooling water is introduced is provided in the thick interior, and will be explained with reference to FIGS. 3 and 4 as follows.

In FIG. 3, which is a partial vertical cross-sectional view, the outer cylindrical surface of the thin cylinder liner 20 is press-fitted into the inner cylindrical surface of the cylinder pull 21 over its entire length.

An annular hollow part 25 for a cooling channel is formed within the wall thickness of the upper part of the block 21 (portion on the cylinder head 22 side), and an annular hollow part 25 is formed within the wall thickness corresponding to the lower part 26 of the liner 20 (the hollow part 25
A cavity 28 is provided within the wall thickness on the side of the crank chamber 27 adjacent to the crank chamber 27.

30 is an inner wall 31 and an outer wall 32 of the cavity 28 (both block 2
1), and are provided at positions corresponding to the lower end portions 33 of the liner.

As shown in FIG. 4, which is a partial cross-sectional view taken along IV-IV in FIG. 3, the illustrated embodiment is intended for a multi-cylinder engine, in which case
No cavities 28 are formed in the partitions 35 between two adjacent cylinders, each cavity 28 extending partially annularly between adjacent partitions 35. It is continuous with the cavity 28.

Further, the plurality of ribs 30 are arranged radially.

Note that in the case of a single cylinder engine, the cross-sectional shape of the cavity 28 may be annular.

In FIG. 3, the upper part 36 of the liner facing the combustion chamber 38 is adjacent to the cooling water W, so it is actively cooled and the upper part 36 of the liner faces the combustion chamber 38.
6 will not be overheated and undergo extremely large thermal expansion, and the gap between it and the piston 37 will not become excessive.

Since the liner lower part 26 which is away from the combustion chamber 38 is also away from the cooling water W, the amount of thermal expansion will not become extremely small due to supercooling, and the gap between it and the piston 37 will not become too small.

In this way, the gaps between the upper part 36, the lower part 26, and the piston 37 are made uniform to a substantially constant predetermined value, so that the crank chamber 27
The lubricating oil inside the combustion chamber 38 and the crank chamber 2
Intrusion (blow-by) of exhaust gas into the piston 7 is suppressed, and seizure of the piston 37 is also prevented.

Since the amount of cooling water W is small, the temperature of each part rises to the appropriate temperature in a short period of time at startup.

By providing the cavity 28, weight reduction has been achieved,
Also, since the lower end of the inner wall 31 is reinforced with ribs 30,
Even if an impact is applied to the liner lower end 33 due to the fluttering of the piston 37 at the bottom dead center, the liner lower end 33 and the inner wall 31 will not be damaged.

As explained above, according to the present invention, the cavity 28 is provided in the cylinder block portion corresponding to the liner lower part 26, so that the gaps between each part of the liner 20 and the piston 37 are approximately equalized, reducing lubricating oil consumption and blow piping. In addition, seizure of the piston 37 can be prevented.

Furthermore, the amount of cooling water can be reduced to shorten the warm-up operation time, and the piston 37 can be prevented from being overcooled, thereby suppressing the generation of blue-white smoke and strange odors at the time of startup.

For example, the air (described later) in the cavity 28 has a greater sound insulation effect than the cooling water W, so it is possible to effectively prevent impact noise caused by the fluttering of the piston 37 at bottom dead center from being transmitted to the outside. can.

Since the rib 30 is provided at the lower end of the cavity 28, weight reduction can be achieved and strength reduction can be prevented.

Opening the lower part of the cavity 28 as in the illustrated embodiment facilitates sand removal (or die cutting) during casting, and the manufacture of the cavity 28 is simplified.

Note that when embodying the present invention, it is also possible to arrange a lightweight filler (such as a resin) in the cavity 28 with heat transfer characteristics different from that of air to adjust the degree of cooling of the liner lower part 26.

The rib 30 can also be provided in an annular or partially annular shape so as to close the lower part of the cavity 28, and in that case, sand for casting can be left in the cavity 28.

Note that leaving the sand will increase the weight somewhat, but since sand is lighter compared to the material of the block 21, the purpose of weight reduction is achieved.

If the vertical length of the cavity 28 is long, another rib may be provided above the rib 30.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional partial views of the conventional example, FIG. 3 is a vertical cross-sectional partial view of the embodiment of the present invention, and FIG. 4 is a partial vertical cross-sectional view of the conventional example.
FIG. 20...Cylinder liner, 21...Cylinder block, 22...Cylinder head, 2
5...Hollow part, 27...Crank chamber,
28...Cavity, 30...Rib, 31.
...Inner wall, 32...Outer wall.

Claims (1)

[Scope of utility model registration request] The entire outer cylindrical surface of the cylinder liner is press-fitted into the inner cylindrical surface of the cylinder block, and an annular hollow part for a cooling waterway is formed in the thick inside of the cylinder head side of the cylinder block, and the crank is adjacent to the hollow part of the cylinder block. A cylinder block for an internal combustion engine, characterized in that an annular or partially annular cavity into which cooling water is not introduced is provided inside the thick wall of the chamber side, and the inner wall and outer wall of the cavity are connected by a rib at the end on the crank chamber side.