JP2000205037A - Cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce engine noise originating from the vibration of the lateral outer walls of cylinder blocks. SOLUTION: A cylinder block 1 includes a bulkhead 10 that connects lateral outer walls 5 and forms a bearing portion 13 for the crankshaft and that contains a cast preform 16 consisting of reinforcing fibers 18 and extending between the lateral outer walls 5. Upon its casting, the preform 16 is impregnated with the molten metal or is combined with it integrally into fiber-reinforced metal(FRM). The bulkhead 10 thereby improves in rigidity to reduce the vibration of the lateral outer walls 5 or reduce the engine noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylinder block applied to a diesel engine or the like.

[0002]

2. Description of the Related Art In general, a cylinder block made of an aluminum alloy, which is advantageous in terms of weight, is frequently used in a gasoline engine, and its use is increasing in the field of a diesel engine in order to promote weight reduction.

[0003]

However, if a high combustion chamber pressure acts as in a turbocharged diesel engine, a problem similar to that of a gasoline engine arises when aluminum alloy is used. . Also, due to the difference in material strength between cast iron and aluminum alloy, the left and right outer walls are vibrated by the vibration generated by combustion in aluminum alloy, generating noise to the outside.

[0004] The combustion pressure acts as a high load on the crankshaft from the piston via the connecting rod. Supporting this crankshaft is a bulkhead adjacent to the cylinder bore. If the strength and rigidity of the bulkhead are insufficient, film vibrations occur on the left and right outer walls of the cylinder block, especially on the skirt portion where the oil pan is attached, and this is a source of engine noise.

Accordingly, an object of the present invention is to reduce engine noise caused by such vibration of the left and right outer walls.

[0006]

According to the present invention, there is provided a cylinder block in which a preform made of reinforced fiber and traversing the left and right outer walls is mounted on a bulkhead connecting left and right outer walls and forming a bearing portion of a crankshaft. It is cast.

[0007] When the preform is cast, the preform is impregnated with a molten metal, and these are integrally combined to form a fiber reinforced metal (FRM). As a result, the rigidity of the bulkhead is increased, vibration of the left and right outer walls is suppressed, and engine noise can be reduced.

Here, it is preferable that the reinforcing fibers are oriented in a direction crossing the left and right outer walls.

Preferably, the cylinder block is made of an aluminum alloy.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, a cylinder block 1 according to the present embodiment is made of an aluminum alloy and is applied to a diesel engine with a supercharger. A plurality (here, three) of cylinder bores 2 are formed in the cylinder block 1 along the front-back direction (the left-right direction in FIG. 2). The cylinder bore 2 is formed by an inner surface of a cylindrical portion 3 that hangs from the top of the cylinder block 1. A water jacket portion 4 for flowing cooling water is formed within the thickness of the cylindrical portion 3. Outer walls 5 are respectively provided on the left and right outer sides of the cylindrical portion 3 so as to be separated from the cylindrical portion 3. The outer wall 5 has a boss hole 6 for attaching auxiliary equipment, a cooling fin 7, and the like integrally formed on an outer surface of the outer wall 5 over the entire height direction of the cylinder block 1.

The reason why the outer wall 5 is separated from the cylindrical portion 3 is that the outer wall 5 is used as a noise prevention cover so that the combustion vibration generated in the cylindrical portion 3 is not directly transmitted to the outer wall 5. For use, the blow-by gas is caused to flow through the gap 8 between the outer wall 5 and the cylindrical portion 3 to cool the cylindrical portion 3 with oil. A through hole 9 is provided in the upper part of the gap 8 so that blow-by gas in the crank chamber is extracted to an upper valve operating chamber. The top surface of the cylinder block 1 is continuous with a substantially constant thickness over the entire surface except for a portion including the cylinder bore 2 and the through hole 9.

A bulkhead (partition) 10 for connecting the left and right outer walls 5 is integrally provided at a position between the cylinder bores 2 and at a position at the front and rear ends of the cylinder block. That is, the bulkheads 10 are provided adjacent to the front and rear of each cylinder bore 2 and partition the cylinder block 1 for each cylinder.
The upper part 11 of the bulkhead 10 has a cylinder bore 2
And a part of the cylindrical portion 3. In addition, a lower portion 12 located below the cylinder bore 2 forms a bearing 13 of a crankshaft (not shown).

That is, the bearing portion 13 has a semicircular bearing surface 14 in the center of the lower surface thereof, and the cap mounting surfaces 1 on both left and right sides thereof.
5, a crank cap (not shown) is fastened to the cap mounting surface 15, and a semi-circular bearing surface 14 and a semi-circular bearing surface of the crank cap facing the semi-circular bearing surface form a circular bearing surface. Surface supports the crankshaft. The bearing part 13 is a cap mounting surface 15
From the height position of the cylinder bore 2 to the height position of the lower end of the cylinder bore 2. Below the cap mounting surface 15, the lower portion 12 does not connect the left and right outer walls 5,
They are merely fixed to the inner surfaces of the outer walls 5 in a rib shape. As a result, a space for inserting the crank cap is secured.

The bulkhead 10 has a basically constant thickness H.
However, as shown in FIG. 2, in the upper portion 11, a portion forming the cylinder bore 2 is partially thinned. FIG. 2 is a cross section taken along a plane including all of the center of the crankshaft and the center of the cylinder bore.

Here, the cylinder block 1 is made by die casting (pressure casting). At this time, a preform 16 made of reinforcing fibers is simultaneously cast into the bearing 13.

The preform 16 is a kind of a preformed body obtained by solidifying a myriad of reinforcing fibers into a predetermined shape with a binder. Types of reinforcing fibers include ceramic fibers, carbon fibers, glass fibers, and alumina powder. In addition, examples of the type of the binder include a resin material such as an epoxy resin. The preform 16 is manufactured in advance before casting the cylinder block. The whole of the preform 16 is formed in a substantially flat plate trapezoidal shape, and a semicircular notch 17 for avoiding the semicircular bearing surface 14 of the cylinder block 1 is provided in the lower center.
The preform 16 after casting is in a state of being set up in a horizontally long state, and crosses the left and right outer walls 5 of the cylinder block 1 over the entire left and right length of the bearing portion 13. Here, long fibers are used for the reinforcing fibers 18, and all the reinforcing fibers 18 are oriented in a direction crossing the left and right outer walls 5 as shown in the figure.
The preform 16 after casting is completely buried in the bearing portion 13 so as to leave the aluminum alloy in the outer periphery.

According to this, the gap between the reinforcing fibers 18 is impregnated with the molten metal at the same time as the casting of the preform 16, and these are integrally combined to form a fiber reinforced metal (FRM).
As a result, the rigidity of the bearing portion 13 of the bulkhead 10 is increased, and further reinforcement of the left and right outer walls 5 is achieved, and the vibration of the left and right outer walls 5, particularly the film vibration of the skirt portion, is suppressed.
Engine noise can be reduced.

Further, the support rigidity of the crankshaft is improved, and the contact with the crank journal is improved, so that the rotational vibration can be reduced. Further, the thermal expansion of the semi-circular bearing surface 14 of the cylinder block 1 is suppressed, and the oil film thickness between the semicircular bearing surface 14 and the crank journal can be appropriately maintained.

In particular, since the reinforcing fibers 18 are oriented in the direction transverse to the left and right outer walls 5, the tensile and compressive strengths in the transverse direction are greatly improved, which is very advantageous for reducing the vibration of the outer walls 5 in this direction. Become. Needless to say, the reinforcing fibers 18 may use short fibers (whiskers) instead of long fibers, and in this case, the orientation does not have to be such.

As described above, the embodiments of the present invention are not limited to those described above. For example, the cylinder block may be made of cast iron instead of aluminum alloy, may be made by low-pressure casting instead of die casting, or may be applied to other than a turbocharged diesel engine.

[0022]

In summary, according to the present invention, an excellent effect of reducing engine noise caused by vibration of the left and right outer walls can be exhibited.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 5 Outer wall 10 Bulkhead 13 Bearing part 16 Preform 18 Reinforcing fiber

Claims (3)

[Claims] 1. A cylinder block in which a preform made of a reinforcing fiber and traversing the left and right outer walls is cast into a bulkhead connecting the left and right outer walls and forming a bearing portion of a crankshaft. 2. The cylinder block according to claim 1, wherein the reinforcing fibers are oriented in a direction transverse to the left and right outer walls. 3. The cylinder block according to claim 1, wherein the cylinder block is made of an aluminum alloy.