JP2000240502A - Cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deformation generated on a bore wall of a cylinder block at the time of fastening a heat bolt, and prevent an increase in the consumption of oil. SOLUTION: This cylinder block 1 has a bore wall 11, and a deck 12 formed on an upper end of the bore wall 11 in the form of a flange. A bolt hole 124 is formed on the deck 12 for fixing a cylinder head with heat bolt. In such a case, a thin portion 121 having thickness less than the other portion 122 is formed between the bolt hole 124 and the bore wall 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block capable of reducing deformation of a bore wall of a cylinder block when tightening a head bolt.

[0002]

2. Description of the Related Art FIG.
This will be described with reference to FIG. The cylinder block 9 is
As shown in FIGS. 10 and 11, a bore wall 91 and a deck portion 92 provided in a flange shape at the upper end thereof are provided. The deck portion 92 is provided with a bolt hole 924 for screwing the head bolt 4 for fixing the cylinder head. The thickness of the deck portion 92 is substantially uniform. In addition, the above-mentioned bore wall 91
Is provided with an engine outer wall 93, between which a water jacket 6 for cooling the bore wall 91 is provided.
Is arranged.

[0003] The cylinder block 9 is constructed as shown in FIG.
As shown in FIG. 2, the cylinder head 5 is disposed on the upper surface of the deck 92 via the head gasket 3, and the cylinder head 5 is used with the cylinder head 5 fixed with the head bolts 4. The head gasket 3 has a bore bead portion 31 having substantially the same shape as the cross section of the bore wall 91. The bore bead portion 31 is slightly thicker and more rigid than other portions. In addition, FIG. 10 is AA in FIG.
FIG. 12 shows a cross section, and FIG. 12 shows a BB cross section in FIG.

[0004]

However, the conventional cylinder block has the following problems. That is, when the head bolt 4 is tightened, as shown in FIG.
A moment is applied to the deck portion 92 with the bore bead portion 31 of the head gasket 3 as a fulcrum and the head bolt 4 as a power point. Thus, as shown on the right side of FIG.
The neighborhood is deformed upward. With this deformation, the bore wall 91 formed integrally with the deck portion 92 is deformed outward in the radial direction.

On the other hand, other general portions of the deck portion 92, for example, portions located between adjacent bolt holes 924 and 924 are hardly subjected to a moment by the head bolt 4 as shown in the left side of FIG. , The upward deformation is relatively small. Therefore, the deformation of the bore wall 91 outward in the radial direction is very small. Therefore, as shown in FIG. 13, the bore wall 91 is locally deformed and the roundness is deteriorated, so that the sealing property between the bore wall and the piston ring is reduced, and the oil consumption is increased. There's a problem.

[0006] To solve this, Japanese Patent Laid-Open No. 6-2130 is disclosed.
As disclosed in Japanese Patent Application Laid-Open No. 64-213065 and Japanese Patent Application Laid-Open No. 6-213065, there is a method of increasing the rigidity of the deck portion 92 to increase the rigidity of the deck portion 92 to suppress the deformation by increasing the thickness of the portion. Are known.

However, in this case, the passage area of the engine cooling water in the water jacket 6 is reduced.
The cooling effect of the bore wall 91 is hindered. In particular,
Since the temperature of the bore wall 91 is likely to be higher in an upper portion closer to the deck portion 92, if the cooling effect of the bore wall 91 is hindered, seizure occurs with the piston ring, and the sealing performance deteriorates. Oil consumption may be further increased. Further, when the temperature of the bore wall 91 rises, the amount of oil evaporation increases, and the oil consumption further increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a cylinder block capable of reducing deformation of a bore wall of a cylinder block when a head bolt is tightened and preventing an increase in oil consumption. Things.

[0009]

According to a first aspect of the present invention, there is provided a bore wall, and a deck portion provided in a flange shape at an upper end portion of the bore wall, and a head bolt for fixing a cylinder head is provided on the deck portion. In a cylinder block provided with a bolt hole for screwing, a thin portion having a smaller thickness than other general portions is provided between the bolt hole and the bore wall in the deck portion. A cylinder block characterized by the above.

The most remarkable feature of the present invention is that the thin portion is provided at a portion of the deck portion where deformation is large, and the thin portion absorbs the deformation of the bore wall at the time of tightening the head bolt. That is.

Next, the operation of the present invention will be described. In the present invention, the thin portion is provided between the bolt hole and the bore wall in the deck portion. Therefore, even if a moment is applied to the deck portion when tightening the head bolt, the transmission of the moment is suppressed by deformation of the thin portion, and deformation of the bore wall outward in the radial direction is absorbed.

Therefore, similarly to the general portion of the deck portion, the deformation of the bore wall is very small, so that the local deformation of the bore wall is reduced and the roundness is improved. Thereby, the sealing performance between the bore wall and the piston ring can be improved, and an increase in oil consumption can be prevented. Therefore, oil consumption can be reduced as compared with the conventional case.

Further, since the thickness of the deck portion is not increased, for example, when cooling the outside of the upper end portion of the bore wall, the area of the cooling passage does not decrease. Therefore, the cooling effect of the bore wall is not hindered. The method of cooling the bore wall is not limited to a water-cooling method using a water jacket or the like, but may be an air-cooling method.

Next, it is preferable that the thin portion is provided on the upper surface of the deck portion. In this case, the thin portion can be provided, for example, by forming a groove on the lower surface of the deck portion at a position corresponding to the thin portion. In addition, for example, when cooling the upper end of the bore wall, the area of the cooling passage increases due to the presence of the groove, and the cooling performance of the bore wall is further improved. Therefore, since the temperature of the bore wall can be further reduced as compared with the conventional case, the amount of oil evaporation can be suppressed, and the oil consumption can be reduced.

As a method of providing the thin portion on the upper surface of the deck, for example, when manufacturing a cylinder block by casting, an upper portion of a core abutting on an outer peripheral surface of the bore wall and a lower surface of the deck portion is provided. There is a method of forming a projection in advance. According to this method, the groove can be easily formed by the presence of the protrusion,
Thereby, the thin portion can be formed.

Next, the thin portion may be provided on the lower surface of the deck portion. In this case, the thin portion can be formed after the cylinder block is cast by subjecting the upper surface of the deck portion to a groove corresponding to the thin portion by, for example, electric discharge machining, milling or the like. Therefore, even when the cylinder block core has a complicated shape and casting is difficult, the thin portion can be easily formed. Note that the thin portion can be formed when the cylinder block is cast, similarly to the case where the thin portion is provided on the upper surface of the deck portion.

Next, as in the fourth aspect of the present invention, it is preferable that a smooth curve is formed between the thin portion and the general portion (FIG. 7). In this case, the deformation of the bore wall is further uniformed in the circumferential direction, and the roundness of the bore wall can be further increased.

Next, as in the fifth aspect of the present invention, it is preferable that an engine outer wall is provided outside the bore wall, and a water jacket is provided between the two. In this case, by cooling the bore wall by the water jacket and improving the cooling performance of the bore wall,
By suppressing the amount of oil evaporation, oil consumption can be further reduced as compared with the conventional case.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A cylinder block according to an embodiment of the present invention will be described.
This will be described with reference to FIGS. In this example, the series 4
1 shows a cylinder block applied to a cylinder engine. The cylinder block 1 of the present embodiment has a
It has a bore wall 11 and a deck portion 12 provided in a flange shape at an upper end portion of the bore wall 11, and a bolt hole 124 for screwing a head bolt 4 for fixing a cylinder head to the deck portion 12 is provided. It becomes. In the deck section 12, between the bolt hole 124 and the bore wall 11, a thin section 121 having a smaller thickness than other general sections 122 is provided.

The details will be described below. The four bore walls 11 are arranged in series with their respective axes being parallel. As shown in FIG. 1, each bore wall 11 has a combustion chamber 10 therein, and a piston (not shown) is reciprocally disposed in the combustion chamber 10. The above bore wall 1
The space between 1 and the piston is sealed by a piston ring. An engine outer wall 13 is provided outside the bore wall 11, and a water jacket 6 is provided between the two.

As shown in FIGS. 1 and 2, the deck section 12 connects the upper ends of the plurality of bore walls 11 and the engine outer wall 13 to each other. As shown in FIG. 1, the bolt hole 124 is formed below the upper surface of the deck 12 at a connection portion between the deck 12 and the outer wall 13 of the engine. In addition, bolt hole 1
Around the periphery, a bolt boss portion 123 bulging outward and inward of the engine outer wall 13 is provided. As shown in FIG. 2, a plurality of the bolt holes 124 are provided at substantially equal intervals around each combustion chamber 10.

The thin portion 121 is, as shown in FIG.
It is provided on the upper surface of the deck section 12. A groove 129 is formed on the lower surface of the deck portion 12 at a position corresponding to the thin portion 121. In addition, the thin portion 1
As shown in FIG. 2, 21 is arranged along the outer periphery of the bore wall 11 in the vicinity of a straight line connecting each bolt hole 124 and the center of the bore wall 11.

As shown in FIG. 3, the thin portion 121 has the smallest thickness on a straight line connecting each bolt hole 124 and the center of the bore wall 11. As shown in FIG. Also,
An arc-shaped curve and a straight line intersect between the thin portion 121 and the general portion 122. 1 shows a cross section taken along line DD in FIG. 2, and FIG.
The E section is shown.

When manufacturing the cylinder block 1 by casting, the thin portion 121 is formed by forming a projection on an upper part of a core for forming the water jacket 6 in advance. Formed at the time of casting.

As shown in FIGS. 4 and 5, the cylinder block 1 is provided with a cylinder head 5 on the upper surface of the deck section 12 via a head gasket 3 and tightened by a head bolt 4. Cylinder head 5
Is used in a fixed state.

As shown in FIGS. 4 and 5, the head gasket 3 has a through hole 30 communicating with the combustion chamber 10 of the cylinder block 1, and has a bolt hole at a position facing the bolt hole 124 of the deck portion 12. 34. The head gasket 3 is provided around the through hole 30 with a bore bead portion 3 having substantially the same shape as the cross section of the bore wall 11.
One. The bore bead portion 31 is slightly thicker and more rigid than other portions. Also, the cylinder head 5 is
The deck portion 12 has a bolt hole 54 at a position facing the bolt hole 124.

Next, the operation of this embodiment will be described. In this example, as shown in FIGS.
, The thin portion 121 is provided between the bolt hole 124 and the bore wall 11. Therefore, even when a moment is applied to the deck portion 12 when the head bolt 4 is tightened, the vicinity of the bolt boss 123 is deformed upward as shown in FIG.
Due to the deformation of 1, the transmission of the moment to the bore wall 11 is suppressed, and the deformation of the bore wall 11 outward in the radial direction is absorbed.

Therefore, similarly to the general portion 122 of the deck portion 12, the deformation of the bore wall 11 is very small, and as shown in FIG. 6, the local deformation of the bore wall 11 is reduced. Roundness is improved. This gives
Improves the seal between the bore wall and the piston ring,
An increase in oil consumption can be prevented. for that reason,
Oil consumption can be reduced as compared with the conventional case.

As shown in FIGS. 1 and 2, the water jacket 6 is disposed outside the bore wall 11, so that the water jacket 6 cools the bore wall 11, and the bore jacket 11 is cooled. The cooling performance of the wall 11 can be improved.

Further, as shown in FIG.
Reference numeral 21 is provided on the upper surface of the deck portion 12, and the groove portion 129 is formed on the lower surface of the deck portion 12. Therefore, the passage area of the engine cooling water in the water jacket 6 is increased by the groove 129, and the cooling performance of the bore wall 11 is further improved. Therefore, since the temperature of the bore wall 11 can be further reduced as compared with the related art, the amount of oil evaporation can be suppressed, and the oil consumption can be further reduced.

Further, since no special additional parts and additional processing are required to reduce the deformation, the deformation of the bore wall 11 can be reduced at low cost. In addition,
The shape of the thin portion 121 is the same as that of the water jacket 6.
Can be changed by changing the shape of the core for forming.

Embodiment 2 As shown in FIG. 7, this embodiment is an example in which a portion between the thin portion 121 and the general portion 122 is formed in a smooth curved shape.
Other structures are the same as those of the first embodiment. In this example, the moment applied to the deck portion 12 does not cause a sharp difference between the thin portion 121 and the general portion 122. Therefore, the deformation of the bore wall 11 is further uniformed in the circumferential direction, and the bore wall 1 is deformed.
The roundness of 1 can be further increased. In addition, the same effects as those of the first embodiment can be obtained.

Embodiment 3 As shown in FIGS. 8 and 9, the present embodiment uses
Is provided on the lower surface of the deck section 12. Other structures are the same as those of the first embodiment. In this example, the thin portion 121 is provided on the upper surface of the deck portion 12.
By performing groove machining by electric discharge machining at a position corresponding to the above, the thin portion 121 can be formed after the cylinder block is cast. Therefore, even when the cylinder block core has a complicated shape and casting is difficult, the thin portion 121 can be easily formed.

Further, at the stage of trial production of the cylinder block, the thin portion 121 is formed by the above-mentioned electric discharge machining, and after confirming the optimum shape, commercialization by casting can be achieved. Therefore, a cylinder block capable of reducing the deformation of the bore wall can be manufactured at low cost. Further, the thin section 121 can be formed by subjecting the conventional cylinder block 9 to post-processing (groove processing). In addition, the same effects as those of the first embodiment can be obtained.

Whether the thin portion 121 is provided on the upper surface or the lower surface of the deck portion 12 is determined in consideration of, for example, the degree of deformation of the bore wall, the temperature of the bore wall, the shape of the cylinder block, and the like. It can be determined for each engine.

[0036]

As described above, according to the present invention, it is possible to provide a cylinder block capable of reducing deformation occurring in the bore wall of the cylinder block when tightening the head bolt and preventing an increase in oil consumption.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cylinder block according to a first embodiment.

FIG. 2 is a plan view of a cylinder block according to the first embodiment.

FIG. 3 is an explanatory cross-sectional view of a thin portion in a circumferential direction according to the first embodiment.

FIG. 4 is an exploded perspective view of a cylinder head and a head gasket according to the first embodiment.

FIG. 5 is a cross-sectional view of the cylinder block at the time of head bolt tightening in the first embodiment.

FIG. 6 is an explanatory diagram of the roundness of a bore wall at the time of head bolt tightening in the first embodiment.

FIG. 7 is an explanatory cross-sectional view of a thin portion in a circumferential direction in a second embodiment.

FIG. 8 is a sectional view of a cylinder block according to a third embodiment.

FIG. 9 is a cross-sectional view of a cylinder block when a head bolt is tightened in a third embodiment.

FIG. 10 is a sectional view of a cylinder block in a conventional example.

FIG. 11 is a plan view of a cylinder block in a conventional example.

FIG. 12 is a cross-sectional view of a cylinder block when a head bolt is tightened in a conventional example.

FIG. 13 is an explanatory view of the roundness of a bore wall when a head bolt is tightened in a conventional example.

[Explanation of symbols]

 1. . . 10. cylinder block, . . Bore wall, 12. . . Deck part, 121. . . Thin part, 122. . . General part, 124. . . 12. bolt holes, . . 2. engine outer wall, . . 3. head gasket, . . Head bolt, 5. . . 5. cylinder head, . . Water jacket,

Claims (5)

[Claims] 1. A vehicle comprising: a bore wall; and a deck portion provided in a flange shape at an upper end portion of the bore wall, wherein a bolt hole for screwing a head bolt for fixing a cylinder head is provided in the deck portion. A cylinder block, comprising: a thin portion having a smaller thickness than other general portions between the bolt hole and the bore wall in the deck portion. 2. The cylinder block according to claim 1, wherein the thin portion is provided on an upper surface of the deck portion. 3. The cylinder block according to claim 1, wherein the thin portion is provided on a lower surface of the deck portion. 4. The method according to claim 1, wherein:
A cylinder block, characterized in that a smooth curve is formed between the thin portion and the general portion. 5. The method according to claim 1, wherein:
A cylinder block, wherein an engine outer wall is provided outside the bore wall, and a water jacket is provided between the two.