JPH11210751A - Cylinder block made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate and ensure the holding of a crank journal bearing member inside a mold. SOLUTION: In a cylinder block 3 made of an aluminum alloy, in which a bulkhead 6 separating crank chambers 5 from one another is integrally formed inward of a skirt part 4 and a crank journal bearing member 1 made of cast iron is cast at the lower end of the bulkhead 6, at least one end 14 of the crank journal bearing member 1 is projected through the skirt part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy cylinder block in which a cast iron crank journal bearing member is cast into the lower end of a bulkhead.

[0002]

2. Description of the Related Art It is well known that a cylinder block is formed of an aluminum alloy in order to reduce the weight of an engine. On the other hand, the crank journal portion that supports the crank journal may be formed of cast iron in order to secure its rigidity.

[0003] Specifically, a bulkhead for partitioning each crank chamber is integrally formed inside a skirt portion below a cylinder block made of an aluminum alloy, and a crank journal bearing member made of cast iron is provided at a lower end portion of the bulkhead. It is designed to be cast. Here, as a conventional structure, both ends of the crank journal bearing member are buried inside the walls of the skirt portions on both sides, and the periphery thereof is covered with an aluminum alloy.

[0004]

When the cylinder block is formed, the cylinder block is cast in a direction in which the crankshaft extends vertically. Therefore, the cast iron crank journal bearing member to be cast must be held in the mold. Therefore, in the conventional support structure of the crank journal bearing member, since the crank journal bearing member is covered with an aluminum alloy, it cannot be directly fixed to the mold, and a pin or a wire is used for the core. Thus, the crank journal bearing member is fixed.

However, when the pin is fixed by using a pin, the insertion hole of the pin must be formed in the crank journal bearing member, so that the number of working steps increases and the rigidity of the crank journal bearing member decreases. There was a problem that would. Further, in the case of fixing using a wire, there is a problem that it takes time and effort to fix, and the crank journal bearing member is displaced in the mold during casting.

[0006] Therefore, it is conceivable to lay the cylinder block in such a direction that the crankshaft becomes horizontal, place the crank journal bearing member on the core, and perform casting. However, considering the workability of the lower end surface of the bulkhead after casting, it is desirable that the lower surface of the crank journal bearing member is covered with aluminum, so the crank journal bearing member must be held slightly floating from the core. Must. Therefore, if the crank journal bearing member is placed, the molten metal does not flow to the lower surface of the crank journal bearing member, and this method cannot be adopted after all, so the crank journal bearing member is fixed to the core using a pin or a wire. And the above-described problem occurs.

The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to provide an aluminum alloy cylinder capable of easily and reliably holding a crank journal bearing member in a mold. Is to provide blocks.

[0008]

In order to solve the above-mentioned problems,
The present invention provides an aluminum alloy cylinder block obtained by integrally forming a bulkhead that partitions each crank chamber inside a skirt portion, and casting a cast iron crank journal bearing member at a lower end portion of the bulkhead. At least one end of the crank journal bearing member is projected through the skirt portion.

According to the above construction, at the time of casting of the cylinder block, at least one end of the crank journal bearing member projecting through the skirt portion can be held by the mold, so that the holding is easy and reliable. can do.

[0010] Preferably, one end of the crank journal bearing member protrudes into a concave portion formed on the outer surface of the skirt portion, and the concave portion is closed by a sealing member.

According to this, the lubricating oil leaking from the crank chamber to the outside of the cylinder head through the joint surface between the crank journal bearing member and the bulk head during operation of the engine can be sealed by the sealing member. Oil leakage can be prevented.

[0012] In addition, if the crank journal bearing member is formed with a tapered portion whose cross section is reduced downward, and the bulkhead is formed so as to cover the tapered portion, the wedge is formed. The effect can improve the binding.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway front view showing an embodiment of an aluminum alloy cylinder block according to the present invention, FIG. 2 is a side view showing a recess, and FIG. 3 is a sectional view taken along line AA of FIG. It is.

As shown in FIG. 1, a bulkhead 6 for partitioning each crank chamber 5 is integrally formed inside a skirt portion 4 formed below a cylinder block 3 made of an aluminum alloy of a V-type engine. I have. A crank journal bearing member 1 for supporting a crank journal 9 of a crankshaft is cast into a lower end of the bulkhead 6.

The skirt 4 is formed at the lower end of the cylinder block 3 on both sides along the longitudinal direction. The bulkhead 6 is continuously joined to the inner surface of the skirt portion 4 on both sides and the upper surface of the crankcase 5 at a position where the crank journal 9 of the crankshaft is located,
An aluminum alloy is formed integrally with the skirt portion 4 so as to cover the upper side of the crank journal 9.

The crank journal bearing member 1 is made of cast iron in order to secure its rigidity, and has a coefficient of thermal expansion substantially equal to that of the crankshaft. The crank journal bearing member 1 is composed of a rod-shaped member 8 having a tapered portion (see FIG. 3) 7 whose cross section is reduced downward over the entire length, and a central portion thereof is a crank journal 9.
Is curved in a semicircular shape along the outer circumference of the.

The crank journal bearing member 1 extends in the width direction of the cylinder block 3, and its substantially entire length is cast into the bulkhead 6. The lower end surface 10 of the crank journal bearing member 1 is covered with a slightly thick aluminum forming the lower end surface of the bulkhead 6.

On the upper surface of the curved portion 25 at the center of the crank journal bearing member 1, two projecting portions 27 each having a hole 26 are integrally formed at a distance from each other. When it is inserted, the molten aluminum flows into the hole 26 to improve the coupling force between the crank journal bearing member 1 and the bulkhead 6.

In this embodiment, both ends 14, 15 of the crank journal bearing member 1 penetrate the skirt portion 4 and protrude outside the cylinder block.

A ring-shaped boss 18 surrounding the projection 16 of the end 14 of the crank journal bearing member 1 is formed on the left skirt portion 4 in the drawing, and a concave portion defined by the boss 18 is formed. The projection 16 is arranged in the inside 17. Further, a concave portion 19 is formed in the skirt portion 4 on the right side in the figure by depressing the outer surface thereof in a circular shape, and the protruding portion 16 is arranged in the concave portion 19.

A sealing cup (sealing member) 21 is fitted into each of the recesses 17 and 19, and during operation after assembly of the engine, the skirt portion 4 and the bulkhead 6 are joined to the crank journal bearing member 1 during operation. The lubricating oil in the crank chamber 5 that seeps out of the surface 22 can be sealed. The outer peripheral surface 23 of the sealing cup 21 is formed in a cup shape along the inner peripheral surface 24 of the concave portions 17, 19.
19 is closed.

The sealing member may be solid, and its fixing method is not limited to fitting, but may be screwing.

Next, a method for casting the aluminum alloy cylinder block 3 according to the present invention will be described.

FIG. 4 is a horizontal sectional view showing a mold and the like when the cylinder block 3 is cast. In this figure, it is a cross-sectional view of the mold and the like as viewed from above, where the cylinder bore portion is a cross-sectional line passing through the center of the cylinder bore, while the crank chamber portion is a cross-sectional line passing through the center of the bulkhead 6. is there.

As shown in FIG. 4, the mold 31 is
2 and movable mold 33 and a plurality of movable molds 34a, 34b, 34
c, 34d. The fixed mold 32 shown on the left side of the figure is a mold for molding the left side surface of the cylinder block 3, and has a projection 35 having a circular cross section for molding the concave portion 17. A hole 36 having the same cross section as the crank journal bearing member 1 is formed. The hole 36 allows the end 14 of the crank journal bearing member 1 to be fitted and held securely. The movable mold 33 shown on the right side in the drawing is also similar to the fixed mold 32,
This is a mold for molding the right side surface of the cylinder block 3, and is formed with a projection 38 having a circular cross section for molding the concave portion 19, and the end 39 of the crank journal bearing member 1 is securely secured by a hole 39 at the tip thereof. Can be held.

There is a slight gap between the crank chamber side movable mold 34a and the lower end of the crank journal bearing member 1 so that molten aluminum can enter.

In order to cast the cylinder block 3, first, the end 14 of the crank journal bearing member 1 is inserted and fixed in the hole 36 of the projection 35 of the fixed mold 32. Next, the crank chamber side movable mold 34a is moved to a predetermined position. Finally, the movable mold 33 is moved to a predetermined position, and the setting of the mold 31 is completed. At this time, the right end 15 of the crank journal bearing member 1 is
And is fixed by being inserted into the hole 39 of the projection 38.

That is, the crank journal bearing member 1
Are formed so that both end portions 14 and 15 penetrate the skirt portion 4 and protrude to the outside.
The protrusion 35 of the fixed mold 32 and the protrusion 38 of the movable mold 33
And can be securely fixed. That is,
The crank journal bearing member 1 is supported at both ends.

After the mold 31 is set, the fixed mold 3
The molten aluminum is injected and filled through the aluminum channel 43 formed in the movable mold 2 and the crank chamber side movable mold 34a. At this time, since the crank journal bearing member 1 is securely fixed by being sandwiched between the fixed mold 32 and the movable mold 33, the crank journal bearing member 1 is cast at an accurate position without causing displacement. As a result, the lower end surface of the crank journal bearing member 1
It will be covered with aluminum of even thickness.

When the aluminum injection and filling are completed, the mold is opened and the cast product is taken out. Thus, the casting of the crank journal bearing member 1 is completed.

Next, the cast product taken out is finished by machining. In particular, the bearing portion of the cylinder block 3 is important because it affects the performance of the engine. Since the crank journal bearing member 1 is securely fixed, the bearing portion can be formed of aluminum having an even thickness on its surface, and the crank journal bearing member 1 made of cast iron having high hardness is provided on its surface. Since it is only necessary to cut and grind aluminum having a relatively low hardness without appearing, finishing work is facilitated and a long life of a cutting tool or the like can be achieved.

Incidentally, the crank journal bearing member 1
End portions 14 and 15 penetrate the skirt portion 4 and protrude to the outside, so that the lubrication inside the crank chamber 5 from the joint surface 22 between the skirt portion 4 and the bulkhead 6 and the crank journal bearing member 1 is performed. It is possible that some oil seeps out. However, recesses 17 and 19 are formed to cover the projecting portion 16 of the crank journal bearing member 1, and these recesses 17 and 1 are formed.
Since the sealing cup 21 is fitted to 9,
Lubricating oil can be reliably shut off from the outside, and oil leakage can be prevented.

In the above embodiment, both ends 17, 19 of the crank journal bearing member 1 are made to penetrate the skirt portion 4 and protrude to the outside.
Only one end may be projected outside the skirt portion 4. In this case, the protruding end of the crank journal bearing member 1 is supported in a cantilever manner. When the cantilever is supported in this manner, the length of the protrusion 16 of the crank journal bearing member 1 is increased, and the hole 36 of the protrusion 35 of the fixed mold 32 is formed deep. Is firmly fixed by inserting it deeply into the hole 36. This long protruding portion will be cut after completion of casting.

The present invention is not limited to the V-type engine,
It is also possible to apply to other types of engines such as an inline engine and a horizontally opposed engine.

[0036]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) The crank journal bearing member can be easily and reliably held in the mold.

(2) Finishing after casting can be facilitated.

(3) Oil leakage from the crank chamber to the outside can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of an aluminum alloy cylinder block according to the present invention.

FIG. 2 is a side view showing a concave portion.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a horizontal sectional view showing a mold and the like when casting a cylinder block.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crank journal bearing member 3 Cylinder block 4 Skirt part 5 Crank chamber 6 Bulkhead 7 Tapered part 14 End part 15 End part 17 Depression 19 Depression 21 Sealing cup (sealing member)

Claims (3)

[Claims] An aluminum alloy cylinder block in which a bulkhead for partitioning each crank chamber is integrally formed inside a skirt portion, and a cast journal bearing member made of cast iron is cast at a lower end portion of the bulkhead. An aluminum alloy cylinder block, characterized in that at least one end of the crank journal bearing member protrudes through the skirt portion. 2. The aluminum alloy cylinder according to claim 1, wherein one end of said crank journal bearing member projects into a concave portion formed on an outer surface of said skirt portion, and said concave portion is closed by a sealing member. block. 3. The crank journal bearing member according to claim 1, wherein a tapered portion whose cross section is reduced downward is formed, and the bulkhead is formed so as to cover the tapered portion. Cylinder block made of aluminum alloy described in Crab.