JP2005090287A - Cylinder block for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize force holding a sleeve, by uniformizing wall thickness of cast thick parts of a cast cylinder block to eliminate solidifying time difference between cast thick parts in casting, in the cast cylinder block made from light alloy with which a sleeve is cast integrally. <P>SOLUTION: The iron cylinder sleeve 2 is cast integrally with an aluminum alloy cylinder block 1, and bolt holes 3a to 3d for tightening the cylinder block 1 are formed in an aluminum casting part covering an outer peripheral part 2a of the sleeve. Connection parts are wide and thick cast connection parts 6a to 6d and connects surrounding parts of the bolt holes 3a to 3d with the outer peripheral part 2a of the sleeve. Thinned parts 8a to 8d are formed in the wide and thick cast connection parts 6a to 6d to uniformize the wall thickness of the aluminum casting part covering the peripheral part 2a of the sleeve. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a cylinder block for an internal combustion engine, and in particular, an improvement of an air-cooled internal combustion engine cylinder block that focuses on eliminating thermal distortion in an Al alloy cylinder block in which an iron sleeve is integrally cast. Regarding technology.

A general cylinder block for an internal combustion engine has an outer shape as shown in the perspective view of FIG. 7, and many of them are made of an iron (cast iron) sleeve having a round cross section made of an Al alloy. It is manufactured by integrally casting with a light alloy such as aluminum alloy or by pressing a steel (cast iron) sleeve into a cylinder block cast with a light alloy such as an Al alloy. Sufficient consideration has not been given to the uniform thickness in consideration of the thermal influence in the light alloy casting portion around the sleeve to be wrapped.
Generally, the periphery of the tightening bolt hole used for tightening the cylinder block to the crankcase and cylinder head is a thick cast part because there is a demand for increased rigidity for tightening the cylinder block. In the structure where the position of the tightening bolt hole is away from the end, there is a tendency that the periphery of the bolt hole becomes a wide thick cast part, and the thickness of the light alloy cast part in which the sleeve is cast is increased depending on the location. They are different (for example, see Patent Document 1).
Under such circumstances, in a cylinder block in which a cast iron cylinder sleeve is cast with a light alloy cylinder barrel, a boss portion is projected from the outer periphery of the cast iron cylinder sleeve, and a cylinder block tightening bolt hole is formed in this boss portion. In some cases, the rigidity of the periphery of the tightening bolt hole is enhanced, thereby bringing the outer peripheral portion of the cylinder block sleeve and the tightening bolt hole close to each other, resulting in a reduction in the cast portion having a wide and thick wall. (For example, refer to Patent Document 2).
Japanese Utility Model Publication No. 62-175249 (first page, FIG. 1) Japanese Utility Model Publication No. 63-119849 (pages 1 and 2; FIGS. 1 and 2)

In the cylinder block 01 of the invention described in Patent Document 1 shown in FIG. 5, the sleeve 02 is press-fitted into the cylinder block 01 cast from a light alloy, but from the outer peripheral portion 02 a of the sleeve 02. The positions of the tightening bolt holes 03a to 03d are away from the sleeve outer peripheral portion 02a. In such a casting cylinder block 01, the thickness of the light alloy cast portion such as an Al alloy covering the sleeve outer peripheral portion 02a is as shown in the figure. The thick cast parts 04a to 04d are extremely wide at the periphery of the tightening bolt holes 03a to 03d. Further, the thick cast parts 04a to 04b around the tightening bolt holes 03a to 03d and the outer peripheral part 02a of the sleeve. The casting parts that communicate with each other are also wide and thick casting communication parts 06a to 06d.

The presence of the above-mentioned wide and thick cast part in the light alloy casting of the cylinder block causes a variation in the thickness in the light alloy cast part such as an Al alloy that wraps around the outer peripheral part of the sleeve. The increase in non-uniformity increases the time difference of the solidification time of the light alloy cast part such as Al alloy during the casting of the cylinder block, and the increase in the solidification time is caused by the shrinkage in the thick cast part in the light alloy cast part. So-called sink marks are generated, thermal strain remains, and a non-uniform force acts on the sleeve whose outer peripheral portion is covered by the light alloy casting portion, thereby adversely affecting the sleeve. In particular, when the sleeve made of iron (cast iron) is integrally cast into the cylinder block, the effect is significant, and the unevenness of the force that covers the sleeve is due to high heat generation during engine operation, etc. In addition, there is a risk of increasing the distortion of the cylinder hole (cylinder bore).

And although the viewpoint of the removal of the bad influence by the presence of the above-mentioned wide and thick cast part is not certain, in the cylinder block 01 of the invention described in Patent Document 2 shown in FIG. 6, the cast sleeve 02 made of cast iron Boss portions 04a to 04d having bolt holes (bolt holes) 03a to 03d for fastening the block 01 are provided on the outer peripheral portion, thereby ensuring the rigidity of the peripheral portions of the bolt holes 03a to 03d. A structure has been disclosed in which 03a to 03d are brought close to the sleeve outer peripheral portion 02a, and as a result, a cast portion having a wide wall thickness is eliminated. However, the cylinder block 01 requires a sleeve 02 having a special structure in which the sleeve 02 is provided with boss portions 04a to 04d for the fastening bolt holes 03a to 03d.

In the situation as described above, a cylinder block made of a light alloy such as an Al alloy having an iron (cast iron) cast-in cylinder sleeve is premised, and a simple structural change and good casting work are maintained. Among them, the time difference in solidification of the cast alloy at the time of casting is eliminated, there is no thermal distortion in casting, the casting sleeve can be held with a uniform force, and the cylinder hole ( Development of the cylinder block in which the cylinder bore) does not deform is awaited.

The present invention relates to an improved structure of a cylinder block for an internal combustion engine for solving the above-described problem, and in a cylinder block for an internal combustion engine in which an iron cylinder sleeve is integrally cast, the width around the cylinder block tightening bolt hole is wide. A thinned portion is provided in a wide and thick cast connecting portion that communicates between a thick cast portion and a thick cast portion in the vicinity of the outer periphery of the sleeve, and the thinned portion is a hollow hole. Further, it is characterized in that the thinned portion is thinned from the lateral direction of the wide and thick cast connecting portion.

The invention according to claim 1 of the present invention is characterized in that the wide and thick cast connecting portion that communicates between the wide and thick cast portion around the cylinder block tightening bolt hole and the thick cast portion near the outer periphery of the sleeve. Since the punched portion is provided, the thickness of the cast portion around the sleeve surrounding the cylinder sleeve can be made uniform, and the difference in the solidification time of the cast portion at the time of casting is eliminated, so that the solidification in the cast portion is eliminated. It is possible to prevent the occurrence of thermal distortion and sink due to the time difference.

Accordingly, since the Al casting part around the sleeve can hold the sleeve evenly, the iron sleeve is uniformly thermally expanded together with the casting part at a high temperature during engine operation. As a result, the consumption of oil and the amount of blow-by gas can be reduced, and the occurrence of piston slap noise and the like is suppressed.

In the invention according to claim 2 of the present invention, in the invention according to claim 1, since the lightening portion is a lightening hole, in addition to the effect in the invention according to claim 1, Since the holes are integrally formed during casting and a relatively simple structure called a hollow hole is adopted, the time difference between the solidification of the cast part while minimizing the strength drop due to the hollow part without impairing the workability in casting. Can be eliminated.

The invention according to claim 3 of the present invention is the invention according to claim 1, wherein in the invention according to claim 1, the thinning portion is thinned from the lateral direction of the wide and thick casting connecting portion. In addition to the above-described effects, the adoption of a simple blanking structure can eliminate the time difference in solidification of the cast part without impairing the workability in casting.

  This is implemented in a cylinder block of an internal combustion engine in which an Fc cylinder sleeve is cast in an Al alloy casting part.

A first embodiment of the present invention will be described with reference to the drawings.
First, the structure of the cylinder block portion 10 to be improved in the present embodiment and its peripheral structure will be described.

FIG. 1 shows a cylinder block portion 10 in an internal combustion engine E and a partial structure in the vicinity thereof.
1, the lower portion of the cylinder block portion 10 is tightened to the crankcase portion 20 and the upper portion thereof is tightened to the cylinder head portion 30. As a result, the crankcase portion 20, the cylinder block portion 10 and the cylinder head 30 are mutually connected. It is tightened integrally with stud bolt B.

A crankshaft 21 illustrated in part in the crankcase portion 20 is rotatably supported via a bearing 22, and a ball bearing 22a is used as a left-side bearing in FIG. A part of the roller bearing 22b used as the bearing 22 is illustrated. A connecting rod 23 is attached to the crankpin 21a of the crankshaft 21 via a large end 23a, and a piston is attached to a small end (not shown) of the connecting rod 23a via a piston pin. Reciprocatingly slides in a cylinder hole 2 (see FIG. 2) formed in the cylinder block 10. These structures are already well known.

In FIG. 1, the reference numeral 24 attached to the crankshaft 21 is a cam chain drive sprocket, which passes from the crankcase portion 20 through the cylinder block portion 10 to the cylinder head portion 30. The extending member 25 is a cam chain guide.

FIG. 2 shows a cross-sectional view in the transverse direction at the center in the up-down direction of the cylinder block 1 before the improvement for the lightening of the cylinder block portion 10 of the internal combustion engine E is performed. The cylinder block 1 has a substantially rectangular outer shape having two long side surfaces A1 and A2 and two short side surfaces B1 and B2 in a cross-sectional view, and the contour of the outer shape itself is substantially the same. The cylinder block 1 is formed by fins F for air cooling.

The cooling fins F are respectively arranged from the outer periphery of the cylinder block 1, that is, from the long side surface and the short side surface of the cylinder block 1, in a plurality of planes arranged at predetermined intervals substantially parallel to the cross section shown in FIG. A plurality of lateral fins F1 (refer to FIG. 1) extending outward and perpendicular to the lateral fins F1, from the outer periphery of the block 1, that is, from the long side and the short side of the cylinder block 1 Each of the plurality of vertical fins F2 extends outward and connects the upper and lower horizontal fins F1.

A cylinder hole 1a is formed in a substantially central portion of the cylinder block 1, and this cylinder hole 1a penetrates the cylinder block 1 in the longitudinal direction. As is well known and as described above, the hole 1a is formed in the cylinder block 1a. It is a hole 1a provided for sliding fitting of a piston (not shown). An opening 1b penetrating the cylinder block 1 in the longitudinal direction is also formed between the cylinder hole 1a and one short side surface B2 forming the substantially rectangular outer shape of the cylinder block 1. The portion 1b is an opening 1b provided for rotational movement of a cam chain (not shown).

By the way, the cylinder block 1 is made of an Al alloy, manufactured by casting, and a cylindrical cylinder sleeve 2 made of iron, for example, Fc, whose cross section is a perfect circle is cast together with the Al alloy at the time of casting. As shown in FIG. 2, the cylinder block 1 has a longitudinal direction so as to open at a substantially central portion of the block 1 in the horizontal sectional view of the central portion in the vertical direction as described above. A cylinder hole 1a for a piston (not shown) is provided through the substantially central portion. For this purpose, the Fc cylinder sleeve 2 is integrally cast in the substantially central portion of the cylinder block 1.

The entire periphery of the cylinder sleeve 2 is completely covered with an Al alloy casting, and the cylinder sleeve 2 is stretched at equal intervals in the longitudinal direction (longitudinal direction) of the outer periphery 2a. A plurality of rib-like protrusions 2b are provided, and the rib-like protrusions 2b contribute to strengthening of casting with an Al alloy in casting.

Two pairs of bolt holes 3a, 3c and 3b, 3d are formed so as to face each other across the cylinder hole 1a of the cylinder sleeve 2, and these bolt holes 3a to 3d form a pair. That is, 3a, 3c and 3b, 3d are formed symmetrically with respect to the cylinder hole 1a, and these bolt holes 3a to 3d are close to approximately 90 ° with the center O of the cylinder hole 1a as the rotation axis. They are formed on lines L1 to L4 extending from the center O and extending radially outward at an angular interval.

These bolt holes 3a to 3d penetrate the cylinder block 1 in the longitudinal direction of the block 1, and these four bolt holes 3a to 3d serve as the cylinder block portion 10 in the internal combustion engine E described above. It is a bolt hole provided in the stud bolt B for fastening to the crankcase part 20 and the cylinder block 30 (see FIG. 1).

Since the four bolt holes 3a, 3b, 3c, 3d used for the tightening of the cylinder block 1 by the stud bolt B are used for the tightening by the bolt B, the strength is maintained and the tightening is stable. In order to increase the degree, the cast parts 4a to 4d are wide and thick, and the wide and thick cast parts 4a to 4d are widened to the thick cast parts 5a to 5d that directly hold the outer peripheral part 2a of the cylinder sleeve 2. It is communicated via thick-walled casting communication parts 6a to 6d.

The wide and thick cast connecting portions 6a to 6d that connect the wide and thick cast portions 4a to 4d around the bolt holes 3a to 3d and the thick cast portions 5a to 5d near the cylinder sleeve outer peripheral portion 2a are shown in FIG. As shown in FIG. 2, a gentle curve is drawn. As a result, the four wide and thick cast forming portions 7a to 7d formed by connecting these are radially outward from the center O of the cylinder sleeve 2, respectively. The four lines L1 to L4 extending in the direction of the line extend on the lines L1 to L4 with a wide shape symmetrically or substantially symmetrically across the lines.

And, the fastening bolt holes 3a to 3d of the stud bolt B are formed at the respective tip portions of the wide and thick cast forming portions 7a to 7d extending on the four lines L1 to L4, As can be understood from FIG. 2, the wide and thick cast forming portions 7a to 7d extending on these four lines L1 to L4 are considerably wider than the widths of other Al alloy cast portions enclosing the cylinder sleeve 2. A thick part is formed.

The cylinder block 1 before improvement in the first embodiment has the above-described structure. In the first embodiment, as shown in FIG. 3, in order to eliminate the adverse thermal effects during casting in the cylinder block 1. In order to make the thickness uniform in the Al alloy casting part, the improvement is made with the viewpoint of making the thickness uniform in the Al alloy casting part surrounding the cylinder sleeve 2 made of Fc. The following improved structure of the cylinder block 1 is employed.

That is, as described above, the cylinder block 1 is formed with the wide and thick cast forming portions 7a to 7d extending on the four lines L1 to L4, respectively, and this wide and thick cast forming portion 7a. 7d is a substantially intermediate portion between the thick cast portions 4a to 4d in the periphery of the stud bolt B tightening bolt holes 3a to 3d and the cast portions 5a to 5d in the vicinity of the outer peripheral portion 2a of the cylinder sleeve 2. The thinned portions 8a to 8d are formed at substantially intermediate portions of the wide and thick cast connecting portions 6a to 6d that connect the two.

As shown in FIG. 1, the thinned portions 8 a to 8 d have a predetermined depth so as to face each other from the upper surface portion of the cylinder block 1 and from the lower surface portion toward the longitudinal direction of the cylinder block 1. The extending hole 9a to 9d is formed as an extending hole 9a to 9d, and the hole 9a to 9d has a cross-sectional shape similar to a ridge with a slightly constricted center (see FIG. 3). However, the cross-sectional shape of the holes 9a to 9d is an example, and the cross-sectional shape of the hollow holes 9a to 9d is of course not limited to this shape. In consideration of workability and the like in casting, an optimum shape is selected.

In the first embodiment, the wide and thick cast forming portions 7a to 7d of the Al alloy cast portion around the sleeve 2 surrounding the cylinder sleeve 2 made of Fc, that is, the periphery of the fastening bolt holes 3a to 3d of the stud bolt B Since the thick and thick cast connecting portions 6a to 6d connecting the wide and thick cast portions 4a to 4d and the cast portions 5a to 5d in the vicinity of the outer peripheral portion 2a of the sleeve 2 are formed with the hollow holes 9a to 9d. Compared with the cylinder block 1 before the improvement shown in FIG. 2, the thickness of the Al alloy cast part in the peripheral part of the cylinder sleeve 2 can be made uniform.

Therefore, the time difference in the solidification of the Al alloy due to the difference in the thickness of the Al alloy cast part during the casting of the cylinder block 1 can be almost completely eliminated, and the occurrence of thermal distortion in the casting is suppressed, and the thick cast part is obtained. The occurrence of sink marks is suppressed, the force of the cast part of the Al alloy holding the Fc cylinder sleeve 2 is made uniform, and the cylinder hole 1a (cylinder bore) is deformed or distorted at high temperatures during engine operation. Is prevented.

The second embodiment differs from the first embodiment in the thickness of the aluminum alloy cast portion in the cylinder block 1 in which the Fc cylinder sleeve 2 is cast, but the other structural portions are not substantially different. Hereinafter, the second embodiment will be described with reference to FIG. 4 focusing on the structure of the thinned portions 8a to 8d of the Al alloy cast portion in the cylinder block 1 in which the Fc cylinder sleeve 2 is cast. In addition, the same code | symbol is used about the structural member substantially the same as the structural member in Example 1. FIG.

In the second embodiment, the thinned portions 8a to 8d for making the thickness uniform in the cylinder block 1 before improvement shown in FIG. 2 are formed by casting a wide and thick wall on the four lines L1 to L4. The parts 7a to 7d, that is, more specifically, the Al alloy casting parts 5a to 5d near the outer peripheral part 2a of the cylinder sleeve 2 and the wide and thick casting parts around the fastening bolt holes 3a to 3d of the stud bolt B 4a to 4d are different from the first embodiment in that they are the thinned portions 8a to 8d in the wide and thick cast forming portions 7a to 7d connected by the wide and thick cast connecting portions 6a to 6d. There is no place.

As shown in FIG. 4, the thinning in this embodiment is performed at the periphery of the fastening bolt holes 3a to 3d of the stud bolts B of the wide and thick cast forming portions 7a to 7d on the four lines L1 to L4. The thick cast parts 4a to 4d and the wide and thick connecting cast parts 6a to 6d are cut from the lateral direction 8a to 8d so as to reduce the width of the cast parts and reduce the width of the cast parts. Therefore, the thickness variation of the Al alloy casting portion surrounding the cylinder sleeve 2 is suppressed as much as possible to achieve uniformization.

In FIG. 4, only the substantially left half of the cylinder block 1 is illustrated, and only the appearance of the thinned portions 8a and 8d of the wide and thick cast forming portions 7a and 7d on the two lines L1 and L4 is shown. Although shown, the same applies to the thinned portions 8b and 8c of the wide and thick cast forming portions 7b and 7c on the two lines L2 and L3 of the other right half of the cylinder block 1 (not shown).

Since this thinning structure is relatively simple, the thickness of the Al alloy cast portion that wraps around the cylinder sleeve 2 made of iron, that is, Fc without impairing the workability in casting for the thinning. As with the invention in the first embodiment, the cylinder block 1 in which the iron cylinder sleeve 2 having no thermal residual strain in casting is cast can be easily obtained.

  The present invention can be applied to light alloy cast parts such as vehicle parts in which iron members are integrally cast.

It is a sectional side view which shows this cylinder block periphery structure of an internal combustion engine provided with the cylinder block to which the improvement technique of this invention is performed. It is a principal figure which shows the cylinder block cross-sectional structure before the improvement of this invention. It is a principal figure which shows the cylinder block cross-sectional structure to which the improvement of this invention was given. (Example 1) It is a principal figure which shows the cylinder block cross-sectional structure in which another improvement of this invention was given. (Example 2) It is a figure which shows the conventional cylinder block, and is a top view of a cylinder block. It is a figure which shows another conventional cylinder block, and is a top view of a cylinder block. It is a perspective view which shows the conventional common cylinder block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 1a ... Cylinder hole, 1b ... Opening part for cam chain, 2 ... Cylinder sleeve, 2a ... Sleeve outer peripheral part, 2b ... Projection part, 3a, 3b, 3c, 3d, ... tightening bolt holes, 4a, 4b, 4c, 4d ... wide and thick cast parts around the bolt holes, 5a, 5b, 5c, 5d ... near the outer periphery of the sleeve Thick cast parts, 6a, 6b, 6c, 6d ... Wide thick cast connecting parts, 7a, 7b, 7c, 7d ... Wide thick cast forming parts, 8a, 8b, 8c, 8d ..Thickening part, 9a, 9b, 9c, 9d ... Thickening hole, 10 ... Cylinder block part, 20 ... Crank case part, 21 ... Crank shaft, 21a ... Crank pin, 22 ... Bearing, 22a ... Ball bearing, 22b ... Roller bearing, 23 ... Connecting rod, 23a ··· Large end of connecting rod, 24 · · · Sprocket for cam chain drive, 25 · · · Chain guide, 30 · · · Cylinder head, 40 · · · Cylinder head cover, A1, A2 · · · Long side, B · ·・ Stud bolts, B1, B2 ... short side, E ... internal combustion engine, F, F1, F2 ... cooling fins, L1, L2, L3, L4 ... lines.

Claims (3)

In a cylinder block for an internal combustion engine formed by integrally casting an iron cylinder sleeve,
An internal combustion system characterized in that a thickening portion is provided in a wide and thick cast connecting portion that communicates between a thick and thick cast portion around the cylinder block tightening bolt hole and a thick cast portion near the outer periphery of the sleeve. Cylinder block for engine. The cylinder block for an internal combustion engine according to claim 1, wherein the lightening portion is a lightening hole. 2. The cylinder block for an internal combustion engine according to claim 1, wherein the thinned portion is thinned from a lateral direction of a wide and thick cast connecting portion.

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