JPH0318678Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to a cylinder block for a seawater-cooled internal combustion engine mounted on an outboard motor.

Conventionally, mixed fuel two-stroke gasoline engines have been mainly used as internal combustion engines for outboard motors mounted on the sterns of small boats.

This is because outboard motors need to be lightweight and compact, and diesel engines, which are heavy and have a large exterior, are rarely used.
In recent years, due to the remarkable rise in the price of gasoline fuel, it has been desired to adopt a diesel engine as an internal combustion engine for an outboard motor.

When a diesel engine is used as an internal combustion engine for an outboard motor, it is heavier than a gasoline engine, and
There is a problem that the external size is quite large, so making the cylinder block, the main part of the internal combustion engine, compact and lightweight has become an important issue in popularizing outboard diesel engines. Therefore, the above purpose can be achieved by integrally casting the cylinder head and cylinder block from aluminum.

On the other hand, the water jacket formed around the cylinder liner was conventionally provided along the entire length of the cylinder liner from the cylinder head side at the top to the crankcase side at the bottom, but it In the case of a seawater cooling type, the temperature of the cooling water can usually only be raised to 40 to 50 degrees Celsius; if the temperature is raised higher than that, salt in the seawater will precipitate and adhere to the walls of the swimsuit, causing heat build-up. There is a problem that the conductivity deteriorates, so it is not recommended to install the water jacket part into which such low-temperature cooling water is introduced below the top surface of the piston in the cylinder liner when the piston is at its lowest point. There is a problem in that the lower part of the cylinder liner is supercooled, causing distortion in the cylinder liner.

Therefore, for the above reasons, distortion of the cylinder liner can be prevented by providing the water jacket around the cylinder liner only from near the top surface of the piston when the piston is at its lowest point to the upper part of the cylinder head side. . Furthermore, a main gear lary hole parallel to the crankshaft is provided near the bottom of this swimsuit section.
Since we have provided an oil hole that reaches the lubricating part of the main bearing from this main gear lary hole, it is possible to provide the main gear lary hole far above the normal position on the cylinder liner outer circumference, and from this main gear lary hole, oil for lubricating the main bearing can be provided. Even if the hole is provided diagonally, there is no risk that the main bearing bolt hole and the oil hole will intersect, and the oil hole can be formed by a single straight passage, making the oil hole construction simple. Become.

Generally, in the case of a cylinder block made of cast aluminum, the strength of the main bearing bolt hole is lower than that of a cylinder block made of cast iron, so the threaded part must also be 1.5 to 2 times as long as that of a cylinder block made of cast iron. There is also
If the unthreaded part of the main bearing bolt on the mating surface side of the main bearing is made as long as possible, the contact pressure applied to the mating surface of the main bearing when tightened with the above thread can be dispersed over a long distance. Therefore, in the case of an aluminum cast cylinder block, it is necessary to drill a very long main bearing bolt hole, but according to the present invention, even if the main bearing bolt hole is long (deep), the main bearing bolt hole can be made long (deep). It is possible to have a structure in which the bearing bolt hole and the oil hole do not intersect.

As mentioned above, the present invention was developed with the aim of making the cylinder block of an internal combustion engine lighter, more compact, and higher in performance.
The purpose is to provide a compact cylinder block.

That is, the present invention is an aluminum seawater-cooled diesel engine in which the cylinder head, cylinder block, and upper half of the crankcase are integrally cast. The main gear hole for lubrication of the main bearing of the diesel engine is formed only in the upper part of the cylinder head side from the vicinity of the top surface of the piston when it is at its lowest point. An oil hole provided in parallel to the crankshaft near the bottom of the suit part and communicating between the main gear lary hole and the main bearing;
It is characterized by being formed by a single linear passage diagonally bored into the cylinder block.

An embodiment of the present invention will be described below with reference to the drawings. The schematic side view of FIG. The diesel engine 2, which is an internal combustion engine for this outboard motor, rotates the propeller screw 4 provided at the bottom of the drive unit 3 to propel the small boat in the direction of arrow A. The outboard motor is operated by moving a steering handle 5 protruding from the front of the outboard motor left and right on the boat.

Next, FIG. 2 is a plan sectional view of the cylinder block 6 inside the diesel engine 2 shown in FIG. 1 taken along the line I--I, and FIG. 3 is a plan view of FIG. 2 viewed from below.

This cylinder block 6 is connected to the cylinder head 7.
The cylinder head 7 has a unit injector insertion hole 9 and a cam chamber 10, and the cylinder block 6 has a cylinder liner for two cylinders. 14 is fitted.

Further, a water jacket part 12 is formed from the outer periphery of the cylinder liner 14 to communicate with the cylinder head 7, and the water jacket part 12 is connected to the cylinder liner 1 shown in FIG.
It is formed only in the upper part of the cylinder head 7 side from the vicinity of the top surface of the piston 13 when it is at its lowest position as shown by the broken line sliding inside the piston 4, and from the top surface of the piston 13 to the crankcase 8 side there is is not formed.

Next, as described above, the water jacket portion 12 provided on the outer circumference of the cylinder liner 14 of the cylinder block 6 is
A main gear lary hole 16 is provided near the bottom of the main gear lary hole 16 in parallel to the vertical crankshaft 11 shown by the dashed line in FIG.
The oil hole 17 for lubrication of the main bearing 15 of this diesel engine 2 that supports the crankshaft 11 is
It is diagonally bored in the cylinder block 6, and the main gear lary hole 16 communicates with the lubricating part of the main bearing 15.

In the cylinder block 6 of the present invention having the above-mentioned configuration, the swimsuit portion 12 is connected to the cylinder liner 14.
Since it is provided only at a relatively upper portion of the outer periphery, there is no swimsuit portion in approximately the lower half of the cylinder block 6. Therefore, the main gear lary hole 16 can be positioned much closer to the cylinder head 7 than the conventional position. As shown in FIG. 2, even if the oil hole 17 extending from the main gear lary hole 16 to the lubricating part of the main bearing 15 is drilled diagonally in a single straight line, it is not provided on the mating surface of the main bearing shown by arrow M. Since there is no risk of penetrating the main bearing bolt hole 18, the main bearing bolt hole 18 can be made sufficiently long, and as a result, the main bearing bolt hole 18 can be made sufficiently long.
8, the threaded portion shown by 18A can be made sufficiently long even considering the strength of the thread as the aluminum cylinder block 6, and the threaded part shown by 18B on the mating surface M side of the main bearing is not threaded. The design can also be made relatively long, so that when a main bearing bolt (not shown) is tightened at the threaded part 18A, the surface pressure on the mating surface M of the main bearing can be dispersed over a long distance.

Further, the water jacket part 12 is provided only at the upper part of the cylinder liner 14 that is heated the most during operation of the diesel engine 2, and the water jacket part 12 is provided at the lower part of the cylinder liner 14 where the temperature is low.
Since this is not provided, overcooling in the lower part of the cylinder liner 14 can be prevented.

Furthermore, when the cylinder head 7 is integrally cast with the cylinder block 6 as in the present invention, the water jacket 12 is cast over the entire length from the cylinder head 7 side to the crankcase 8 side of the cylinder liner 14, as in the conventional case. If such a core is provided, the core at the time of casting will be very long and large, and in order to make the diesel engine 2 lighter and more compact, it is necessary to It is also necessary to make the thickness as thin as possible,
It is extremely difficult to manufacture such a thin and long core.

Furthermore, in the area indicated by arrows X and Y in FIG. If the distance to the bottom of the cast member 14 is long and the thickness t of the core is small, there is a problem that the core is likely to break and that it is difficult to remove sand from the water jacket part 12 after casting, and the casting accuracy also decreases. However, there was a problem in that the defective rate also increased.

However, in the present invention, since the water jacket portion 12 is provided only from the intermediate position of the cylinder liner to the cylinder head 7 side, the above-mentioned problems during casting can be solved.

Therefore, if the cylinder block of the present invention is applied to a seawater-cooled outboard internal combustion engine, overcooling of the lower part of the cylinder liner, where the temperature does not rise much, can be prevented, and distortion of the cylinder liner can be prevented. Even when the cylinder head and cylinder block are integrally cast, the casting becomes easier.
Moreover, there is an effect that casting accuracy is improved and the defective rate is reduced.

In addition, since the main gear lary hole can be provided in the upper part of the cylinder liner, the length of the main bearing bolt hole can be made sufficiently long, and even in an aluminum cylinder block, the main bearing bolt hole can have sufficient strength. can.

In particular, by applying the present invention, it is possible to use an aluminum cylinder block, and the cylinder block can be made lighter and more compact, allowing diesel engines to be used as internal combustion engines for outboard motors. It is extremely effective in doing so.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of an outboard motor for a small boat equipped with a diesel engine having a cylinder block to which an embodiment of the present invention is applied, and Fig. 2 shows the cylinder block inside the diesel engine shown in Fig. 1. I-
FIG. 3 is a plan view of FIG. 2 viewed from below. 6...Cylinder block, 7...Cylinder head, 11...Crankshaft, 12...Water jacket, 13
...Piston, 14...Cylinder liner, 15...
...Main bearing, 17...Oil hole, 18...Main bearing bolt.

Claims (1)

[Scope of utility model registration request] In an aluminum seawater-cooled diesel engine in which the cylinder head, cylinder block, and upper half of the crankcase are integrally cast, the water jacket provided on the outer periphery of the cylinder liner is connected to the lowest position of the piston that slides inside the cylinder liner. The main gear hole for lubricating the main bearing of the diesel engine is formed only in the upper part of the cylinder head side from near the top surface of the piston. The oil hole is provided near the bottom parallel to the crankshaft and connects the main gear lary hole and the main bearing, and is formed by a single linear passage diagonally bored in the cylinder block. Aluminum seawater cooled diesel engine cylinder block.