JP2002138897A - Cylinder block structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit a liner displacement caused by a displacement of an outer wall part of a cylinder block at the time of tightening a cylinder head. SOLUTION: A gap R1 having a predetermined length as an inhibition part for inhibiting that a displacement caused by a tightening of a long size bolt is transmitted to a liner 3 is formed on a press-fit part of an outer wall part 2b of a cylinder block 2 and the liner 3 corresponding to a position where the long size bolt is tightened to a head tightening hole 4. The gap R1 is formed on a lower part in a longitudinal direction of the liner 3 from a stepped part 3c, i.e. the thickest part of the outer wall part 2b of the cylinder head 2 and is formed on the outer wall part 2b of the cylinder block 2 and/or the liner 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block structure of an engine for suppressing displacement of a liner caused by fastening a cylinder head to a cylinder block.

[0002]

2. Description of the Related Art A conventional cylinder block structure of an engine is formed by press-fitting a liner made of cast iron into an outer wall portion of a cylinder block made of an aluminum alloy. For example, Japanese Unexamined Patent Publication No. Hei 6-63825 discloses that the upper part is made thicker and the lower part is made thinner in the length direction of the liner to form a step on the outer wall portion of the liner, and that the press-fit allowance at the lower part of the liner is increased. A structure in which the mounting strength and the accuracy by press-fitting are improved.

[0003]

In the structure described in the above publication, a fastening hole for fastening the cylinder block is formed in the outer wall of the cylinder block on the outer periphery of the liner,
The cylinder block and the cylinder head are fixed by inserting bolts into the fastening holes and fastening. However,
Due to the fastening of the fastening holes and the bolts, the outer wall of the cylinder block is displaced as shown in FIG. 4B, and the liner is displaced following this displacement.

When the thickness of the outer wall of the cylinder block is greater than a predetermined thickness in a direction perpendicular to the center axis of the liner, the cylinder block shrinks around the liner center axis at extremely low temperatures. However, there is a problem that the liner is displaced following this.

[0005] Due to such displacement of the liner, when the piston ring of the piston is located at the displaced portion, the blow-by gas increases, or the lower portion of the piston or wear between the piston ring and the liner is locally generated. Problems such as an increase in noise occur.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a cylinder block structure of an engine capable of suppressing displacement of a liner due to displacement of an outer wall portion of a cylinder block when the cylinder block and a cylinder head are fastened. That is.

[0007]

In order to solve the above-mentioned problems and achieve the object, a cylinder block structure of an engine according to the present invention includes a cylinder block made of light metal and an outer wall portion of the cylinder block. A liner forming a cylinder bore, and the cylinder block comprises:
In order to perform fastening with the cylinder head, a fastening hole formed in the length direction of the liner is provided in an outer wall portion of the cylinder block near the liner, and a bolt is inserted through the fastening hole.
In the cylinder block structure of the engine in which the cylinder head is fixed to the cylinder block by being fastened, in a fitting portion between the outer wall portion of the cylinder block and the liner located near a fastening portion between the fastening hole and the bolt,
A suppressing portion is provided for suppressing the deformation due to the bolt fastening being transmitted to the liner.

Preferably, the suppressing portion is a gap formed in an outer wall portion of the cylinder block or the liner.

[0009] Preferably, the suppressor reduces the concentration of the light metal material in the space formed in the outer wall of the cylinder block or the liner.

[0010] Preferably, the liner corresponding to a fastening portion between the fastening hole and the bolt is thin, and an upper portion of the liner in the longitudinal direction of the fastening portion is formed thick.

Preferably, the thickness of the liner above the fastening portion between the fastening hole and the bolt in the longitudinal direction of the liner is smaller than the thickness of the outer wall portion of the surrounding cylinder block.

A cylinder block structure of an engine according to the present invention includes a cylinder block made of light metal, and a liner fitted to an outer wall of the cylinder block to form a cylinder bore. In order to perform fastening, the cylinder block has an fastening hole formed in the length direction of the liner in the outer wall of the cylinder block near the liner, and a bolt is inserted into the fastening hole and fastened to fix the cylinder head to the cylinder block. In the cylinder block structure of the engine, the thickness of the outer wall portion of the cylinder block in the direction perpendicular to the center axis of the liner is greater than or equal to a predetermined thickness in a centrifugal direction from the center axis. The deformation due to the bolt fastening is transmitted to the liner at the fitting portion between the outer wall portion of the and the liner. It was provided to suppress suppressing portion from that.

Preferably, the thickness of the outer wall of the cylinder block on one side with respect to the length direction of the liner is smaller than the thickness of the outer wall of the cylinder block on the other side.

[0014]

As described above, according to the first aspect of the present invention, the deformation due to the bolt fastening occurs at the fitting portion between the outer wall portion of the cylinder block and the liner corresponding to the fastening portion between the fastening hole and the bolt. The provision of the suppressing portion that suppresses transmission to the liner can suppress displacement of the liner due to displacement of the outer wall of the cylinder block when the cylinder block and the cylinder head are fastened.

According to the second aspect of the present invention, since the suppressing portion is a gap formed in the outer wall portion or the liner of the cylinder block, the displacement of the outer wall portion of the cylinder block when the cylinder block and the cylinder head are fastened. And the displacement of the liner can be suppressed.

According to the third aspect of the present invention, since the concentration of the light metal material in the space formed in the outer wall of the cylinder block or in the liner is reduced, the post-processing for forming the restriction is performed. Is unnecessary and can be integrally formed, so that mass productivity can be improved.

According to the fourth aspect of the present invention, the liner corresponding to the fastening portion between the fastening hole and the bolt is made thin, and the upper portion in the length direction of the liner from the fastening portion is made thick. The displacement of the upper portion of the liner due to fastening with the cylinder head can be suppressed while reducing the weight of the liner.

According to the fifth aspect of the present invention, the thickness of the liner above the fastening portion between the fastening hole and the bolt in the longitudinal direction of the liner is smaller than the thickness of the outer wall of the surrounding cylinder block. Thus, the displacement of the upper portion of the liner due to fastening with the cylinder head can be suppressed while reducing the weight of the liner.

According to the sixth aspect of the present invention, the thickness of the outer wall portion of the cylinder block in the direction perpendicular to the center axis of the liner is more than a predetermined thickness in the centrifugal direction from the center axis. At the fitting part of the outer wall part and the liner,
By providing a restraining portion that suppresses the deformation due to bolt fastening from being transmitted to the liner, the shrinkage is absorbed by the restraining portion at the thick wall portion of the outer wall portion where the shrinkage increases at extremely low temperatures of the cylinder block. Can be suppressed, and it is not necessary to provide a gap between the piston ring and the inner wall of the liner in consideration of contraction in advance.

According to the seventh aspect of the invention, the thickness of the outer wall of the cylinder block on one side with respect to the length direction of the liner is smaller than the thickness of the outer wall of the cylinder block on the other side. In the thick part of the outer wall where the shrinkage increases when the block is extremely low temperature, the shrinkage can be absorbed by the suppressor to suppress the displacement of the liner. There is no need to provide a gap in the space.

[0021]

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

The embodiment described below is an example of a means for realizing the present invention, and the present invention can be applied to a modification or a modification of the following embodiment without departing from the gist of the present invention. .

FIG. 1 is a plan view of a cylinder block according to the present embodiment. FIG. 2 is a sectional view taken along line II of FIG. FIG. 3 is a sectional view taken along line II-II of FIG. FIG. 4 is a diagram showing a main part of a cross section taken along line III-III of FIG.

As shown in FIGS. 1 to 4, as an example of this embodiment, an in-line multi-cylinder diesel engine 1 for an automobile
The engine 1 includes an aluminum alloy cylinder block 2 in which four cylinders L1 to L4 are arranged in series.

A cylinder head (not shown) is fastened to an upper end (top deck) 2a of the cylinder block 2 by long bolts, and a cast iron liner 3 forming a cylinder bore is press-fitted to an outer wall 2b of the cylinder block 2. ing.

The liner 3 forms each cylinder of the cylinder block 2, and a piston 5 is slidably inserted into the inner wall 3a of each cylinder (liner 3).

A bearing cap 8 for supporting the crankshaft 7 is mounted in the crankcase 2d of the cylinder block 2. The bearing cap 8 is fastened to the cylinder block 2 by a plurality of long bolts 9.

In the outer wall portion 2b of the cylinder head 2, a head fastening hole radially disposed near the outer periphery of the liner 3 as viewed from the top deck 2a and extending in the length direction of the liner 3 for fastening with the cylinder head. The cylinder head is fixed to the cylinder block 2 by inserting a long bolt through the head fastening hole 4 and fastening the bolt with a predetermined torque.

A step 3c is formed in the outer peripheral portion 3b of the liner 3 at a predetermined position in the longitudinal direction of the liner 3, and the head fastening hole 4 and the long bolt are fastened with the step 3c as a boundary. The lower part t2 is formed thinner than the position where the screw groove 4a is formed, and the upper part t1 is formed thicker than the position where the screw groove 4a is formed.

A step 2c is formed on the outer wall 2b of the cylinder block 2 in contact with the step 3c of the liner 3 corresponding to the shape of the outer periphery 3b of the liner 3.
The upper part t1 is formed thick with the boundary of c, and the lower part t2 is formed thin.

Incidentally, the piston ring descends to a height corresponding to the step 3c which is hard to the sliding movement of the piston.

With this structure, while the weight of the liner 3 is reduced, the upper part t2 of the liner 3 is fastened by fastening to the cylinder head.
Can be suppressed.

The thickness of the liner 3 in the upper part t1 of the liner 3 in the longitudinal direction from the position where the head fastening hole 4 and the long bolt are fastened is the thickness of the outer wall 2b of the cylinder block 2 around the liner 3. The water jacket 6 is formed between the liner 3 and the outer wall portion 2b separated from the liner 3 so as to be smaller than t3.

On the lower side of the water jet,
A groove 11 for cooling the liner 3 with oil splashed by rotation of the crankshaft is formed.

With this structure, the weight of the liner 3 is reduced, and the lower part t2 of the liner 3 is fastened to the cylinder head.
Can be suppressed.

In this embodiment, the head fastening holes 4
As a suppressing portion that suppresses transmission of displacement due to fastening of the long bolt to the liner 3 at a press-fit portion between the outer wall portion 2b of the cylinder block 2 and the liner 3 corresponding to a position where the long bolt is fastened. A gap R1 having a predetermined length (in FIG. 4, at least the height at which the outer wall portion 2 is displaced in the plus direction toward the liner side at least below the engine than the step portion 2c) is formed.

The gap R1 extends from the step 3c, which is the thickest portion of the outer wall 2b of the cylinder head 2, to the liner 3
And is formed on the outer wall 2 b and / or the liner 3 of the cylinder block 2. Also,
The gap R1 should have a depth t4ha and an interval equal to or greater than the displacement amount, preferably 20 μm or more, and the upper limit may be several 100 μm or less. Further, the screw groove 4a formed in the head fastening hole 4 shrinks by several millimeters downward from the step portion 3c in a region t5 corresponding to the height region of the deck portion 11a in a direction perpendicular to the sliding direction of the piston. It is formed so as to penetrate from the lower end of the shrinkage allowance to the lower end of the outer wall portion 2b, leaving the allowance 4b.

Instead of the gap R1, a nickel porous body or the like which is hardly impregnated with the aluminum alloy melt is cast into a portion corresponding to the gap formed in the outer wall portion 2b of the cylinder block 2 or the liner 3 as a suppressing portion. Even if the concentration of the aluminum alloy in the portion is reduced, it is effective to suppress the displacement of the liner 3.

Even if the gap R1 is provided uniformly around the entire outer wall 2b of the cylinder block 2 and / or the outer periphery 3b of the liner 3, it is only partially provided near the portion where the long bolt is fastened. May be provided.

According to this configuration, post-processing for forming the gap is not required, and the liner can be integrally manufactured without press-fitting the liner, so that mass productivity is further improved. .

As shown in FIG. 4B, the head fastening holes 4
The displacement of the outer wall portion 2b of the cylinder block 2 that occurs when the long bolt is fastened to the liner 3 becomes large near the step portion 3c which is the thickest portion of the outer wall portion 2b of the cylinder head 2. Greatly affects the sealing property between the inner wall 3a and the piston ring and the sliding property with the piston skirt.

According to the above configuration, the fastening strength is increased by arranging the step 3c at the position where the displacement of the outer wall 2b of the cylinder block 2 is maximum, and the displacement of the outer wall 2b is absorbed by the gap R1. Therefore, the displacement of the liner 3 can be suppressed without transmitting the displacement to the liner 3.

The step 2c of the cylinder block 2
With respect to a direction perpendicular to the central axis L of the liner 3,
The outer wall portion 2b of the cylinder block 2 has a thickness greater than a predetermined thickness in the centrifugal direction from the center axis L, and a gap R
By providing 1, even when the thick portion of the outer wall portion 2 b that shrinks greatly at a very low temperature of the cylinder block 2, that is, the thick portion near the step portion 2 c shrinks at a very low temperature, the gap R 1 The displacement of the liner 3 can be suppressed by absorbing the contraction, and there is no need to provide a gap between the piston ring and the inner wall of the liner in consideration of the contraction in advance.

Since the head fastening holes 4 are arranged on the outer wall 2b of the cylinder head 2 at substantially 90 ° intervals around the outer peripheral portion 3b of the liner 3, when the cylinder block 2 and the cylinder head are fastened to each other. The displacement of the liner 3 causes a fourth deformation which affects the sealing performance of the oil ring. However, by providing the gap R1, the fourth deformation of the liner 3 can be reduced to prevent deterioration of the oil consumption and the like. .

It should be noted that the present invention can be applied to a modification or a modification of the above embodiment without departing from the gist of the invention.

For example, the present invention is applicable not only to diesel engines but also to gasoline engines and other internal combustion engines.

[Brief description of the drawings]

FIG. 1 is a plan view of a cylinder block according to the present embodiment.

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

FIG. 3 is a sectional view taken along line II-II of FIG.

FIG. 4 is a diagram showing a main part of a section taken along line III-III of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 3 Liner 4 Head fastening hole 5 Piston 6 Water jacket 7 Crankshaft 8 Bearing cap R1 Clearance

Claims (7)

[Claims] 1. A cylinder block made of light metal, and a liner fitted to an outer wall of the cylinder block to form a cylinder bore. The cylinder block is used for fastening with a cylinder head. In a cylinder block structure of an engine having a fastening hole formed in a length direction of the liner in a nearby cylinder block outer wall portion, a bolt is inserted into the fastening hole, and the cylinder head is fixed to the cylinder block by fastening. At a fitting portion between the outer wall portion of the cylinder block and the liner, which is located near a fastening portion between the fastening hole and the bolt, a suppressing portion that suppresses transmission of deformation due to the bolt fastening to the liner is provided. A cylinder block structure for an engine. 2. The cylinder block structure for an engine according to claim 1, wherein the suppressing portion is a gap formed in an outer wall portion of the cylinder block or the liner. 3. The cylinder block structure of an engine according to claim 1, wherein the suppression portion reduces the concentration of a light metal material in an outer wall portion of the cylinder block or a space formed in the liner. . 4. The liner corresponding to a fastening portion between the fastening hole and the bolt is made thin, and an upper portion of the liner in the length direction from the fastening portion is made thick. The engine cylinder block structure according to claim 1. 5. A thickness of the liner above a fastening portion between the fastening hole and the bolt in a longitudinal direction of the liner,
2. The engine cylinder block structure according to claim 1, wherein the thickness of the cylinder block is smaller than the thickness of the outer wall of the surrounding cylinder block. 6. A cylinder block made of light metal, and a liner fitted to an outer wall portion of the cylinder block to form a cylinder bore, wherein the cylinder block is used for fastening with a cylinder head. In a cylinder block structure of an engine, which has a fastening hole formed in the length direction of the liner in a nearby cylinder block outer wall portion, a bolt is inserted into the fastening hole, and the cylinder head is fixed to the cylinder block by fastening. In a direction perpendicular to the center axis of the liner, the outer wall of the cylinder block and the liner are formed such that the thickness of the outer wall of the cylinder block is greater than or equal to a predetermined thickness in a centrifugal direction from the center axis. The fitting portion is provided with a suppressing portion that suppresses transmission of the deformation due to the bolt fastening to the liner. A cylinder block structure of the engine to be. 7. The wall thickness of the outer wall of the cylinder block on one side with respect to the length direction of the liner is smaller than the thickness of the outer wall of the cylinder block on the other side. The cylinder block structure of the engine according to the above.