JPH109043A - Cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a cold shut when a covering is formed, as well as to prevent a crack generated to the covering to cover the connections of the cylinder liners, and a relief to the covering, in a cylinder block casting the liner connections. SOLUTION: In a cylinder block 11 in which a liner connection body 15 is casted together with the molding of a block main body 38, and the upper end fances of the first and the second connections of the cylinder liners 21 are made to be covered by the coverings 41 at the main body 38 side, a recess 36 is formed to the upper end face of the connection to be a part of the above connection, and the projection 42 of a covering piece 41a to be a part of the covering 41, is fitted to the recess 36, so as to prevent the generation of crack of the covering 41. And the recess 36 and the projection 42 prevent the separation of the first and the second connections by the engaging relation of the engaging projection and the engaging groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block of an engine, and more particularly, to a cylinder block in which a problem that occurs in a cylinder block in which a cylinder liner is cast is solved, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a cylinder block for a multi-cylinder internal combustion engine, there is a cylinder block 83 in which a liner connecting body 82 is cast in a block body 81 as shown in FIG. The connected liner 82 is a component made of a hard particle composite aluminum alloy obtained by extrusion molding, and is configured by connecting cylinder liners 84 corresponding to the number of cylinders in series at a connecting portion 85. In order to obtain the cylinder block 83 in which the liner connection body 82 is cast, the following steps are performed.
First, the liner connector 82 is placed in a casting mold, and a molten metal such as an aluminum alloy is poured into the casting mold. When the molten metal cools and hardens, the liner connector 82
Is obtained, and the block main body 81 is obtained. And
The inner peripheral surface of the cylinder liner 84 is cut again to form the cylinder bores # 1 and # 2, whereby the cylinder block 83 is obtained.

Generally, an upper end surface 82a of a liner connector 82 is cast in a block body 81. Since the head gasket (not shown) is mounted on the upper surface of the cylinder block 83, the upper end surface 82a of the liner connector 82
Are not exposed on the upper surface side of the block body 81 to enhance the sealing performance of the head gasket. Therefore, the upper end surface 82a of the liner connector 82 is covered with the covering portion 86 of the block body 81 (the molten metal at the stage of casting).
Covered by As shown in FIG. 25, the covering portion 86 is formed so as to protrude from the upper end edge of the outer peripheral wall 87 surrounding the liner connection body 82 toward the inner periphery.
6 is integrated with the outer peripheral wall 87. However, as shown in FIG. 24, the cylinder bores # 1, #
2, that is, in the connecting portion 85 of the liner connecting body 82, the outer peripheral wall 87 of the block body 81 and the thin covering piece 8
We are in contact only at 6a. The covering piece 86a is connected to the connecting portion 8
5 is arranged on the upper end surface 85a and is formed in a thin plate shape (thickness of about 3 to 8 mm) apart from the inner peripheral wall 87.

[0004]

In the cooling process, the block body 81 hardens while shrinking (about 0.6%).
A tensile stress (thermal stress) is generated in the block body 81 made of an aluminum alloy having a large coefficient of thermal expansion due to the difference between the materials. Covering portion 8 covering upper end surface 82a of liner connector 82
6, tensile stress is also generated, but the portion of the connecting portion 85 protruding from the inner peripheral wall 87 other than the upper end surface 85a is formed continuously with the inner peripheral wall 87, so that the generated stress can be dispersed. . However, the covering piece 86a covering the upper end surface 85a of the connecting portion 85 is on the narrow connecting portion 85, and as shown in FIG. 24, has a very small thickness and a small cross-sectional area. Accordingly, since the tensile stress applied to the covering piece 86a cannot be sufficiently dispersed, a crack F may be generated in the covering piece 86a exceeding the strength limit value.

[0005] Further, in the amount of elongation caused by thermal expansion during actual operation, the covering piece 86a on the connecting portion 85 made of an aluminum alloy is larger than the connecting portion 85 of the cylinder liner 83 made of a hard particle composite aluminum alloy. In particular, FIG.
3, the covering piece 86a covering the upper end surface 85a of the connecting portion 85 extends due to insufficient cross-sectional area in the P direction (a direction orthogonal to the line connecting the center lines L of the cylinder bores # 1 and # 2). As a result, the covering piece 86a relatively extends beyond the connecting portion 85 and the connecting portion 8
There was a possibility that a problem of rising from the position No. 5 would occur.

[0006] As shown in FIG. 26, at the time of casting, the covering piece 86 a is attached to the inner peripheral wall 8 surrounding the liner connecting body 82.
The molten metal No. 7 rises and is formed so as to wrap around from the left and right in the figure. Therefore, a hot spot Q is formed on the coating piece 86a, and the hot spot Q may become a starting point of the crack when a tensile stress is generated in the coating piece 86a.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to provide a cylinder block in which a liner connection body is cast, and a cover for covering a connection portion of each cylinder liner. A second object of the present invention is to provide a cylinder block capable of preventing the occurrence of cracks and a method of manufacturing the same. Third
It is an object of the present invention to provide a method of manufacturing a cylinder block in which a hot junction is not formed when forming a covering portion.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a liner connecting body to which a cylinder liner is connected is cast together with the molding of the block body, and at least a connecting portion of each of the cylinder liners is connected. In the cylinder block configured such that the cylinder head side end surface is covered by the covering portion of the block body, a recess is formed in the cylinder head side end surface of the connecting portion, and the fitting formed in the covering portion in the recess. The gist is that the parts have been fitted. With such a configuration, the fitting portion of the covering portion is fitted into the concave portion formed on the cylinder head side end surface of the connecting portion of each cylinder liner. As a result, the cross-sectional area of the covering portion that covers the connecting portion of the cylinder liner is increased by the area of the fitting portion as compared with the case without the concave portion, and the tensile stress generated at the same portion in the cooling process causes insufficient cross-sectional area. Never be.

According to the second aspect of the present invention, the liner connecting body to which the cylinder liner is connected is cast together with the molding of the block body, and at least the cylinder head side end surface of the connecting portion of each of the cylinder liners is covered with the covering portion of the block body. In the cylinder block configured so as to be covered by the cover, the gist is that an engagement means for preventing separation between the connection portion and the covering portion covering the connection portion is formed. With such a configuration, since the connection portion of each of the cylinder liners and the covering portion covering the connection portion are engaged by the engagement means, the covering portion does not separate from the connection portion.

According to the third aspect of the present invention, an engaging means for preventing separation between the connecting portion and the covering portion covering the connecting portion is formed, and the fitting portion of the covering portion is provided on each cylinder liner. Are connected to concave portions formed on the cylinder head side end surface of the connecting portion. Therefore, the operation of claim 2 is produced in addition to the operation of claim 1.

According to a fourth aspect of the present invention, there is provided the method of manufacturing a cylinder block according to the first aspect, wherein a concave portion communicating with the runner on the crankshaft side is formed in an end surface of the connecting portion of each cylinder liner on the cylinder head side. The gist of the present invention is that the recess is filled with the molten metal through the runner to form a fitting portion, and the cast-out portion of each cylinder liner is formed by the molten metal flowing out of the recess. With such a configuration, the fitting portion is formed of the molten metal filled in the concave portion.
Then, since the cast-in portion of each cylinder liner is formed by the molten metal flowing out of the concave portion, the covering portion covering the connecting portion of the cylinder liner is formed of the molten metal flowing from the concave portion, so that there is no boundary. Therefore, the covering portion covering the connecting portion of the cylinder liner does not become a starting point of the crack.

According to the fifth aspect of the present invention, the liner connecting body to which the cylinder liner is connected is cast together with the molding of the block main body, and at least the cylinder head side end surface of the connecting portion of each of the cylinder liners is covered by the covering portion of the block main body. In the cylinder block configured so as to be covered by the cover, the covering portion covering the connecting portion of each of the cylinder liners is formed by removing a raised portion raised from the deck surface of the block body. In such a configuration, a raised portion is formed in a state of a block coarse material,
The raised portion is removed after cooling. Accordingly, the tensile stress is reduced by the raised portion, and cracks in the covering portion at the raised portion position can be suppressed.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the protruding portion is formed in a mountain shape having a larger swelling amount toward a center. Therefore, it shrinks largely toward the center where the amount of protrusion is large, and the tensile stress is further reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, Embodiment 1 in which a cylinder block of the present invention is embodied will be described with reference to FIGS. FIG. 7 shows a cylinder block 11 for an in-line four-cylinder engine. As shown in FIG.
In the engine E whose component is
A cylinder head 13 is mounted on an upper part of the cylinder 1 via a head gasket 12, and an oil pan (not shown) is mounted on a lower part of the block 11. The lower part of the block 11 is a crankcase 14, in which a journal 19 for supporting a crankshaft is formed. The cylinder block 11 includes a liner connection body 15 having the same number of cylinder bores # 1, # 2, # 3, and # 4 as the number of cylinders. In each of the cylinder bores # 1 to # 4, a piston 17 on which a piston ring 16 is mounted is reciprocally accommodated. The upper space of each of the cylinder bores # 1 to # 4 has a combustion chamber 18 for burning a mixture of fuel and air.
A part of.

First, the liner connector 15 constituting the cylinder block 11 will be described. As shown in FIGS. 1 and 3, the liner connector 15 is a first cylinder liner 2.
1, a second cylinder liner 22, a third cylinder liner 23, and a fourth cylinder liner 24 are connected to each other. Each cylinder liner 21-24 is made of silicon, iron, copper,
It is composed of a liner material including a matrix powder such as magnesium, manganese, nickel, and aluminum, alumina (AI ₂ O ₃ ), and graphite powder. Each of the cylinder liners 21 to 24 has a center line L of an outer peripheral surface 25 and an inner peripheral surface 2.
6 is a cylindrical body whose center line L2 coincides, and is formed by extrusion. Cylinder bores # 1, # 2, # 3, and # 4 are formed in each of the cylinder liners 21 to 24 by cutting and grinding.

The positions of the cylinder liners 21 to 24 opposite to each other with respect to the center line L are a first connecting portion 31 and a second connecting portion 32 which are connecting portions. The first connecting portion 31 is provided with a first ridge 33 projecting outward from the outer peripheral surface 25, and the first ridge 33 is provided with the center lines L, L.
It extends in the up-down direction in parallel with 2. 2nd connection part 3
2 is provided with a pair of second ridges 34 projecting outward from the outer peripheral surface 25. The second ridges 34 extend vertically in parallel with the center line L at positions separated from each other. The first protrusions 33 of the adjacent cylindrical portions 28 (29, 30) are fitted between the two second protrusions 32, and are fixed by the silicone-based adhesive C to form the connection portions 3.
5 are formed. The cylinder liners 21 to 24 are connected in series by the connecting portion 35 to form a liner connector 15.
Is configured.

As shown in FIG. 4, the upper end surface 35a of the connecting portion 35 has a Q direction (each cylinder bore # 1, # 2, # 3).
A concave portion 36 extending in a direction perpendicular to the line connecting the center line L of # 4 is provided. The long side edge 36a of the concave portion 36 is curved along the inner peripheral surface 26 of each of the cylinder liners 21 to 24, and the concave portion 36 has a drum-shaped planar shape. The length of the recess 36 is the same as the width of the first protrusion 33. The depth of the recess 36 is approximately the same as the width between the adjacent cylinder bores # 1, # 2, # 3, and # 4. A pair of engaging ridges 37 projecting inward from each other along the longitudinal direction is provided at the upper edge of the concave portion 36.

Next, the block body 38 constituting the cylinder block 11 will be described. The block body 38 is obtained by pouring a molten metal made of an aluminum alloy into a casting mold (not shown), and then cooling and hardening. As shown in FIG. 7, the liner connection body 15 is cast in the block body 38. Cylinder bores # 1 and # 2 are formed by cutting the inner peripheral surfaces of the cylinder liners 21 to 24 that are cast into the block body 38. Further, the cylinder block 11 is obtained by cutting the head bolt hole 44.

The block body 38 has an inner peripheral wall 39 which is in close contact with and surrounds the liner connector 15.
On the outer peripheral side of the inner peripheral wall 39, each of the cylinder bores # 1 to #
Water jacket 40 is formed so as to surround 4. The water jacket 40 is the block body 3
8 and a water channel for cooling the liner connector 15. A ring-shaped covering portion 41 is provided on the inner periphery of the upper edge of the inner peripheral wall 39.
Are formed to protrude, and each cylinder liner 21 to 2
4 covers the entire upper end surfaces 21a to 24a. The first
On the upper end surfaces 31a and 32a of the second connecting portions 31 and 32 (on the upper end surface 35a of the connecting portion 35), a coating piece 41a forming a part of the coating portion 41 not directly in contact with the inner peripheral wall 39 is arranged. Has been established. On the back surface of the covering piece 41a, a convex portion 42 as a fitting portion is formed. An engagement groove 43 is formed at the base of the protrusion 42 to engage the engagement protrusion 37 of the recess 36. The shape of the convex portion 42 in which the engaging groove 43 is formed corresponds to the shape of the concave portion 36 in which the engaging ridge 37 is formed, and both are fitted without any gap. The concave portion 36 and the convex portion 42 are formed with cylinder bores # of cylinder liners 21 to 24 on both sides thereof.
1, # 2, # 3, and # 4 are arranged equidistant from the center line L.

Next, the operation of the thus configured cylinder block 11 will be described. The liner connector 15 is set in a casting mold, and a molten metal such as an aluminum alloy is poured into the casting mold. Then, when the molten metal is cooled and hardened, a block main body 38 in which the above-described liner connection body 15 is cast is obtained. Here, the liner connector 15 is cast into the block body 81, and the upper end surface 15 a is covered by the covering portion 41 of the block body 38. The covering piece 41a on the upper end surfaces 31a and 32a does not contact with the inner peripheral wall 39 like other parts of the covering portion 41 other than the covering piece 41a. However, as shown in FIG. 6, the unit area of the covering piece 41 a cut along a plane parallel to the straight line R connecting the center lines L of the cylinder bores # 1, # 2, # 3, # 4 is equal to the unit area of the projection 42. Only increase. Therefore, the covering piece 41a
When the molten metal becomes hardened by cooling, Q in FIG.
The tensile stress (thermal stress) generated in the direction does not result in insufficient cross-sectional area and does not cause cracking. In addition, due to thermal expansion during actual operation, the amount of elongation of the covering piece 41a made of an aluminum alloy is larger than that of the first and second connecting portions 31 and 32 made of the liner material. However, since the engaging projection 37 protruding from the concave portion 36 on the connecting portion 35 and the engaging groove 43 concave from the convex portion 42 on the back surface of the covering piece 41a are in an engaged state, the upper end surface 31a, The covering piece 41a on 32a (upper end surface 35a) does not rise.

With this configuration, the first embodiment has the following effects. (1) Covering piece 4 covering first and second connecting portions 31 and 32
By forming the convex part 42 on the back surface of 1a, the covering piece 41a
Can be enlarged. Therefore, even if the connecting portions 31 and 32 are formed to have the same width as that of the related art, the possibility of cracking due to tensile stress is reduced.

(2) In order to increase the sectional area of the connecting portions 31 and 32, the width of the connecting portions 31 and 32 is increased or
Means for projecting the upper surface side of 1a is also conceivable. But,
The widening leads to an increase in the size of the liner connector 15, and
When projecting the upper surface side of 1a, the head gasket 12
In some cases may cause a decrease in the sealing performance of the device. With the above-described configuration, the cracks can be prevented without increasing the width of the connecting portions 31 and 32 to secure the cross-sectional area. As a result, the length of the liner connecting body 15 is shortened, and the cylinder is pulled. This contributes to making the block 11 lightweight and compact. In addition, since the upper surface side of the covering piece 41a does not need to project, the sealing performance of the head gasket 12 on the cylinder block 11 does not deteriorate.

(3) The first and the second are determined by the engagement relationship between the engagement protrusion 37 protruding from the recess 36 of the connection portion 35 and the engagement groove 43 recessed from the protrusion 42 on the back surface of the covering piece 41a. It is possible to prevent the covering portion 40 on the second connecting portions 31 and 32 from rising due to thermal expansion. Therefore, the sealing performance of the head gasket mounted on the upper surface of the cylinder block 11 is enhanced.

(4) The convex portion 42 of the covering piece 41a secures a cross-sectional area and is securely fitted into the concave portion 36 of the connecting portion 35 in an uneven relationship. Therefore, the covering piece 41
and the rigidity around the upper end surface 35a of the connecting portion 35 (the upper end surfaces of the first and second connecting portions 31 and 32) is increased, so that cracks are less likely to occur than simply caused by an increase in cross-sectional area. In addition, the connecting portion 35 is made of first and second members having high rigidity.
The projections 33 and 34 make it more difficult for cracks to occur.

(5) The protrusions 42 and the recesses 36 have cylinder bores # 1, # 2 of the cylinder liners 21 to 24 on both sides thereof.
Since they are arranged equidistant from the center lines L of # 3 and # 4 and the distribution of stress is equalized, the covering piece 41a and the upper end surface 35a of the connecting portion 35 (the first and second connecting portions 31, 32
The rigidity around the upper surface increases. The long side edge 36 a of the concave portion 36 is curved along the inner peripheral surface 26 of the adjacent cylindrical portion 27. Therefore, the concave portion 36 and the cylinder bores # 1, #
The intervals between # 2, # 3, and # 4 are constant, and the dispersion of stress around the concave portion 36 is equalized. (Embodiment 2) Hereinafter, Embodiment 2 that embodies a cylinder block of the present invention will be described with reference to FIGS. The cylinder block 11 according to the second embodiment is also a component that forms an engine similarly to the first embodiment. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. First, the liner connector 15 constituting the cylinder block 11 will be described. The cylinder liners 21 to 24 have a cylindrical portion 27,
First to third connecting portions 45 and 4 which are connecting portions forming a part thereof
6, 47.

As shown in FIG. 8, in the second embodiment, not all the cylinder liners 21 to 24 have the same shape, but the second cylinder liner 22 and the third cylinder liner 22 located in the middle. Only 23 have the same shape as each other. Therefore, the liner connector 15 is constituted by three types of cylinder liners having different shapes.

A part of the cylindrical portions 27 of the first cylinder liner 21 and the fourth cylinder liner 24 is
It has been. A first joint 48 projects outwardly from the first and fourth connecting portions 45, and the joint 48 extends vertically in parallel with the center line L of each of the cylinder liners 21 to 24. Have been. The positions opposite to each other with respect to the center line L of the cylindrical portion 27 of the second cylinder liner 22 and the third cylinder liner 23 are second and third connecting portions 46 and 47. Second and third joints 49, 50 project outwardly from the connecting portions 46, 47, respectively. The joints 49, 50 are connected to the respective cylinder liners 21-2.
4 extend in the vertical direction in parallel with the center line L. A flat joint surface 51 is formed on the front surface of each of the joints 48, 49, 50.

The first connecting portion 45 of the first cylinder liner 21 is connected to the second connecting portion 46 of the second cylinder liner 22. First joint portion 48 of first connecting portion 45
A pair of grooves 52 extending along the center line L
Are formed, and the first joint portion 4 of the second connecting portion 46 is formed.
A pair of ridges 53 formed on the joint surface 51 of FIG. Third connecting portion 47 of second cylinder liner 22
Is connected to the second connecting portion 46 of the third cylinder liner 22. Similarly to the above, the groove 52 of the third connecting portion 47 and the ridge 53 of the second connecting portion 46 are fitted. The third connecting portion 47 of the third cylinder liner 23 is connected to the first connecting portion 45 of the fourth cylinder liner 24. Similarly to the above, the second connecting portion 46 is inserted into the groove 52 of the third connecting portion 47.
Are fitted. Each cylinder liner 21 to
The connecting portions 45, 46, 47 of the 24 are fixed with an adhesive C.

An inter-bore cooling water passage 54 communicating with the water jacket 40 is formed between the cylinder liners 21 to 24. The distance from each inter-bore cooling water passage 54 to each of the cylinder bores # 1 to # 4 on both sides is equal, and the cooling water flowing through the cooling water passage 54 causes each cylinder liner 2
1 to 24 are cooled evenly.

As shown in FIGS. 9 to 11, concave portions 55 are formed in the upper end surfaces 48a and 49a of the first and second joints 48 and 49 between the first cylinder liner 21 and the second cylinder liner 22, respectively. Have been. The long side edge 55a of the concave portion 55 is curved along the inner peripheral surface 26 of each of the cylinder liners 21 to 24, and the concave portion 55 has a drum-shaped planar shape. The length of the concave portion 55 is slightly shorter than the interval between the pair of ridges 53 formed on the joint surface 51. The depth of the concave portion 55 is approximately the same as the width between the adjacent cylinder bores # 1 and # 2. A pair of engaging ridges 56 projecting inward from each other along the longitudinal direction is provided at the upper edge of the concave portion 55. Although not shown, the second and third cylinder liners 2
The recesses 55 having the same shape are formed in the second and third cylinder liners 23 and 24 as well.

Next, the block body 38 constituting the cylinder block 11 will be described. The method of manufacturing the block body 38 and the cylinder block 11 is the same as that of the first embodiment, and a description thereof will be omitted.

A covering portion 57 is formed on the inner periphery of the upper end edge of the inner peripheral wall 39 so as to project therefrom, and covers the entire upper end surfaces 21a to 24a of the cylinder liners 21 to 24. The joint 4
On the upper end surfaces 48a, 49a, 50a of 8, 49, 50, a coating piece 57a forming a part of the coating portion 57 which is not directly in contact with the inner peripheral wall 39 is formed. On the back surface of the covering piece 57a, a convex portion 58 as a fitting portion is formed. At the base of the projection 58, the engagement groove 5 with which the engagement ridge 56 of the recess 55 is engaged.
9 are formed. The convex portion 5 having the engaging groove 59 formed therein
The shape of 8 corresponds to the shape of the concave portion 55 in which the engaging ridge 56 is formed, and both are fitted without any gap. The concave portion 55 and the convex portion 58 are disposed equidistant from the center line L1 of the cylinder bores # 1, # 2, # 3, and # 4 of the cylinder liners 21 to 24 on both sides thereof. A communication hole 60 is formed near both ends of the covering piece 57a to allow the cooling water passage 54 between the bore and the water jacket 40 to communicate with each other.

The operation of the second embodiment is the same as that of the first embodiment. The second embodiment is similar to the first embodiment (1) to (1).
The same effect as (5) is achieved. (Embodiment 3) Hereinafter, Embodiment 3 which embodies a cylinder block of the present invention will be described with reference to FIGS. The cylinder block 11 according to the third embodiment is also a component constituting an engine, similarly to the first and second embodiments. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and illustration or description thereof is omitted, and only essential parts are illustrated and described.

The cylinder liners 21 to 24 (however, only the cylinder liners 21 and 22 are shown) are
And first and second connecting portions 3 which are connecting portions forming a part thereof
1, 32. Each cylinder liner 21-2
4 is connected by the first and second connection portions 31 and 32 to form the liner connection body 15. A large number of ribs 61 extending parallel to the center line L are formed on the outer periphery of the cylindrical portion 27. The positions opposite to each other with respect to the center line L of the cylinder liners 21 to 24 are a first connection portion 31 and a second connection portion 32 which are connection portions. The first connecting portion 31 is provided with a pair of first protrusions 33 projecting outward from the outer peripheral surface 25, and the protrusions 33 extend in the vertical direction in parallel with the center line L. I have. The second connecting portion 32 is provided with a second ridge 34 protruding outward from the outer peripheral surface 25, and the ridge 34 extends in a vertical direction in parallel with the center line L.

As shown in FIG. 14, the distance between the outer wall surfaces of the first ridges 33 is substantially equal to the distance between the inner wall surfaces of the second ridges 34, and both the first ridges 33 are provided. 33 is both second ridges 34
They are arranged in a fitted state between them. As a result, the recess 6 surrounded by the first ridges 33 and the second ridges 34
2 is formed between the first and second connecting portions 31 and 32.
The recess 62 extends from the upper end to the lower end of the cylinder liners 21 to 24.

Next, the block body 38 constituting the cylinder block 11 will be described. The block body 38 is obtained by pouring a molten metal made of an aluminum alloy into a casting mold 65 described below, and then cooling and hardening the metal. As shown in FIG. 7, the liner connection body 15 is cast in the block body 38, and the cylinder liners 21 to 2 are formed.
The inner peripheral surface of No. 4 is subjected to cutting to make cylinder bores # 1 and # 2
Is obtained.

The block body 38 is formed with an inner peripheral wall 39 which is a cast-in portion which is in close contact with and surrounds the liner connector 15. A coating portion 41 is provided on the inner periphery of the upper edge of the inner peripheral wall 39.
Are formed to protrude, and each cylinder liner 21 to 2
4 covers the entire upper end surfaces 21a to 24a. The first
And a covering piece 41 forming a part of a covering portion 41 not directly in contact with the inner peripheral wall 39 on the upper end surfaces of the second connecting portions 31 and 32.
a is provided. On the back surface of the covering piece 41a, a fitting portion 63 fitted in the concave portion 62 without a gap is formed. The fitting part 63 is connected to the covering part 41 at the upper part,
The lower part is connected to the journal 19.

Next, the cylinder block 1 of the third embodiment
1 will be described. Liner connector 15
(A) of disposing in a casting mold and (B) of molding the block body 38.

Step (A) of Placing Liner Linkage 15 In this step (A), a casting mold 65 shown in FIGS. 15 and 16 is used. The casting die 65 includes an upper fixed die 66, a first side movable die 67, a second side movable die 68, a lower movable die 69, and a positioning and holding mechanism 70. Holes 71 corresponding to the number of cylinder liners 21 to 24 (four in the third embodiment) are provided in the upper fixed die 66. A molding protrusion 72 for molding a water jacket is formed on the lower surface of the upper fixed die 66.

The first side movable die 67 is disposed on the left side of the forming protrusion 72 in the figure, and the second side movable die 68 is disposed on the right side, and reciprocates in the horizontal direction. The lower movable mold 69 reciprocates vertically and approaches and separates from the upper fixed mold 66. The positioning and holding mechanism 70 is for positioning and holding the liner connector 15 disposed on the casting mold 65.

The liner connector 15 is attached to such a casting mold 65.
In order to dispose the movable molds 66 to 69, the movable molds 66 to 69 are separated from each other (the mold is opened), the liner connector 15 is mounted on the positioning mechanism 69, and the movable molds 66 to 69 are moved again in the direction of the forming protrusion 72 (approaching). ) To close the mold.

Step (B) of Forming Block Body 38 In this step, the liner connector 15 is used as an insert.
This is cast with an aluminum alloy.
Depending on the step (A), the liner connector 15 and each of the dies 66 to 6
9, a cavity 73 for molding the block body 38 is formed. A molten metal material (molten metal) is poured into the cavity 73 through the runner 74 of the lower movable mold 69.

The molten metal introduced from the runner 74 is filled in the crankcase area 73a in the cavity 73,
As shown in FIG. 18, journal areas 7 are formed at a total of five places (only three places are shown) at three places between the cylinder liners 21 to 24 and two places at both end positions of the liner connector 15.
3b. Next, the molten metal rises using each journal area 73b as a runner, and the liner cast-in area 73 is filled.
c. Here, when the molten metal ascending using the concave portion 62 as a runner reaches the upper fixed die 66, it flows out from the covering piece 41a to the surrounding liner cast-in area 73c as shown by the broken line in FIG. That is, the hot water flows into the concave portion 62 before the inner peripheral wall 39 where the liner is cast. Then, the molten metal overflowing from the covering piece 41a merges with the molten metal rising in the liner cast-in area 73c.

The metal material poured into the cavity 73 in this way hardens with shrinkage of about 0.6%. And each cylinder liner 2 of the taken out block coarse material
The inner peripheral surfaces of Nos. 1 to 24 are cut and the head bolt holes 4
4 is cut to obtain a cylinder block 11. Here, as shown in FIG. 17, a tensile stress (thermal stress) in the S direction is generated in the covering piece 41a when contracted. However, since the covering piece 41a is formed integrally with the fitting portion 63, the sectional area does not become insufficient, and the tensile stress is reduced.

Further, since the covering piece 41a is formed integrally with the fitting portion 63 by the molten metal flowing from the concave portion 61,
There is no hot spring. With this configuration, the manufacturing method according to the third embodiment has the following effects.

(1) Since the covering piece 41a is formed integrally with the fitting portion 63 by the molten metal rising in the concave portion 62, the sectional area does not become insufficient, and the cracking of the covering piece 41a due to tensile stress is prevented. .

(2) The amount of elongation of the covering piece 41a made of an aluminum alloy becomes larger than that of the first and second connecting portions 31 and 32 made of the liner material due to thermal expansion during actual operation. However, the covering piece 41a is integrated with the fitting portion 63, and the covering piece 41a is connected to the first and second connecting portions 31,3.
2 does not rise from the upper end surface.

(3) The covering piece 41a is formed only of the molten metal flowing from the concave portion 61. The molten metal rising in the liner cast-in area 73c does not hit the covering piece 41a to form a molten metal boundary. Therefore, the covering piece 4
Even if a tensile stress occurs in 1a, no crack is formed starting from the hot water boundary. (Embodiment 4) Hereinafter, Embodiment 4 which embodies a cylinder block of the present invention will be described with reference to FIGS. The cylinder block 11 according to the fourth embodiment is also a component that constitutes the engine similarly to the first to third embodiments.
In the fourth embodiment, the description of the same components as those in the first embodiment is omitted.

As shown in FIGS. 19 and 20, unlike the first embodiment, no recess 36 is formed in the upper end surface 35a of the connecting portion 35 in the fourth embodiment. That is, the upper end surfaces 21a to 24a of the cylinder liners 21 to 24 are formed in a planar shape.

In the fourth embodiment, a molten metal is poured into a casting mold (not shown), and the molten metal hardens to
5 is formed into a block coarse material BB. A raised portion 75 is formed in the covering portion 41 of the block coarse material BB at the position of the connection portion 35. The raised portion 75 is composed of an inclined portion 76 formed so as to gradually increase toward the connecting portion 35, and a top portion 77 formed thickest with respect to other portions at the center of the connecting portion 35. The inclined portions 76 are formed at four positions on the covering portion 41 near the connecting portion 35, and are connected to the top portion 76 at the upper edge of the inclined portion 76. Therefore, the raised portion 7 of the covering portion 41
5 has a Mt. Fuji shape as a whole when viewed from the side as shown in FIG.

Then, a cutting line C is cut by a cutting jig (not shown).
The raised portion 75 is cut so that the deck surface of the block body 38 and the covering portion 41 are flush with each other. With the raised portion 75 cut off, the covering piece 4 is formed on the upper end surface 35a of the connecting portion 35.
1a is formed. And, each cylinder liner 21-2
The inner peripheral surface of No. 4 is cut, and the head bolt hole 44 is further cut to obtain the cylinder block 11.

FIG. 21 shows the direction of stress generated when the molten metal shrinks due to cooling and hardening, and is particularly generated on the covering piece 41a near the upper end surface 35a of the connection portion 35.
For comparison (a), the conventional cylinder block 83,
(B) Cylinder block 11 of another example and (c) three cylinder blocks 11 of the fourth embodiment. However, the raised portions 75 in (b) and (c) are in a stage before being deleted. FIG. 22A shows these (A) to (C).
23B is a graph showing the residual stress levels measured at the measurement positions I, II, and III shown in FIG. 22B at the stage when each block main body is processed into a cylinder block. This measurement was performed by removing the raised portion 75 of (b) and (c).

In the cylinder block 83 of the comparative example (a), the cross-sectional area of the covering portion 86 is small,
The coating piece 86a in the vicinity of “a” also has the same cross-sectional area as the other coating portion 86. Therefore, a crack cannot be formed because of the tensile stress caused by the contraction of the molten metal indicated by the white arrow. That is, as shown in the graph, each measurement position I, II,
III shows a high residual stress, and a stress higher than the tensile strength of the aluminum alloy is generated at the measurement position II.

The cylinder block 11 of another example (b) has a covering portion 41 on which a raised portion 75 having no inclined portion 76 is formed at the stage of the block coarse material BB. Therefore, the cross-sectional area of the covering piece 41a and the surrounding covering portion 41 increases, and cracks are less likely to occur during cooling as compared with the cylinder block 83 of the comparative example (a). Furthermore, the raised portion 75 has a larger mass during cooling than the surrounding covering portion 41, and therefore contracts in the center direction, effectively canceling the tensile stress. Therefore, in the other example (B), even if the covering piece 41a has the same thickness as that of the comparative example (A), the direction of hot water flow during cooling is toward the center of the raised portion 75 (black in FIG. 21 (B)). (In the direction of the arrow), the tensile stress is reduced and cracks are unlikely to occur.

Cylinder block 1 of this embodiment (c)
In FIG. 1, near the center of the connection portion 35 at the stage of the block coarse material BB,
That is, the cross-sectional area of the covering portion 41 is increased at the top portion 76, and cracks are less likely to occur as compared with the comparative example (A). Compared with another example (b), the raised portion 75 has a Mt. Fuji shape, and the molten metal contracts toward the center with a large cross-sectional area at the position of the raised portion 75 during cooling, so that the molten metal is effectively canceled with the tensile stress. Here, since the raised portion 75 of another example (b) does not have the inclined portion 76 and has a uniform thickness, the contraction force toward the center is not as strong as in the present embodiment (c). However, in the present embodiment (c), the entire raised portion 75 contracts greatly toward the center as compared with the other example (b). Therefore, in the covering piece 41a having the same thickness as that of the comparative example (a) after removing the raised portion 75 in the present embodiment (c), the amount of stress offset by the tensile stress is larger than another example (b).

As described above, since the shrinking force (flow of hot water at the time of cooling) of the raised portion 75 in the center direction is larger than that of the comparative example (a), the other example (b) and the present embodiment (c) Even if the raised portion 75 after curing is deleted, the residual tensile stress is reduced.

With this configuration, the cylinder block 11 according to the manufacturing method of the fourth embodiment has the following effects. (1) Since the raised portion 75 is formed, the contraction force toward the center thereof is large, and the residual tensile stress is reduced in the cylinder block 11 in which the raised portion 75 is not cured after curing.
Cracks are less likely to occur.

(2) Since the raised portion 75 has a Mt. Fuji shape, the residual tensile stress is further reduced and cracks are less likely to occur as compared with the other example (b). As described above, the embodiment has been described in the present invention, but the present embodiment can be implemented by being changed to another mode.

A. In the first embodiment, the cylinder liners 21 to 24 obtained by extrusion molding are connected at the connection portion 35 to form the liner connection body 15. In the second embodiment, each of the cylinder liners 21 to 24 is
The liner connector 15 was configured by being connected at 49 and 50. However, the liner connection 15 is
1 to 24 may be integrally connected from the beginning without being connected later. Further, the inter-bore cooling water passage 54 of the second embodiment does not necessarily have to be formed. In short, it is sufficient that a connecting portion is formed between the cylinder liners 21 to 24.

B. For example, the width of the concave portion 36 formed in the connecting portion 35 of the cylinder liners 21 to 24 of the first embodiment is increased to fill the entire width of the first connecting portion 31 and the second connecting portion 32, that is, the cylinder bores # 1 and # You may make it communicate between two. Further, the long side edge 36 of the concave portions 36, 55
The lengths, widths and depths of the concave portions 36 and 55 are determined according to the magnitude of the tensile stress and the standard of the cylinder block 11, for example, a and 55a need not be curved along the inner peripheral surface 26 of the cylinder liners 21 to 24. Can be changed as needed.

C. The length, shape, and position of the engaging ridges 37, 56 and the engaging grooves 42, 59, which are the engaging means, can be appropriately changed according to the magnitude of the tensile stress and the standard of the cylinder block 11.

D. In the third embodiment, as shown in FIG. 15, the liner connector 15 is arranged so that the crankcase 14 is formed on the lower side when the block body 38 is cast.
The molten metal is filled from the lower runner 74 side. However, it is possible to freely change the arrangement position of the liner connector 15 and the filling direction of the molten metal.

E. In the fourth embodiment, the flat top 77
The raised portion 75 has the shape of a mountain having the shape of Mt. Fuji, but may have the shape of a pointed mountain having no flat portion. Further, even if the connecting portion 35 does not have a mountain shape as in another example (b),
It is only necessary to provide a raised portion 75 for increasing the cross-sectional area of the upper end surface 35a.

F. The material of the liner connection body 15 may be cast iron, alloy cast iron, or MMC (metal composite material). g. In the first and second embodiments, the cylinder block 11 is for an in-line four-cylinder engine. However, the present invention is not limited to this, and any cylinder block having two or more cylinders is applicable. In addition, the present embodiment can be freely modified and implemented without departing from the spirit thereof.

Further, other technical ideas grasped by the above embodiments will be described below together with their effects. (1) In the cylinder block according to claim 1 or 3, the positions of the concave portion and the convex portion are arranged at an equal distance from the center of the bore of the cylinder liner on both sides of the connecting portion. By doing so, the tensile stress is evenly distributed around the connection portion and the periphery of the connection portion, and the rigidity is improved.

(2) In the cylinder block according to the first aspect, the cylinder liners are connected and connected by a connecting portion having a connecting structure, and a concave portion is formed on an end surface of the connecting portion on the cylinder head side. A projection formed on the covering portion is fitted to the cylinder block. In this case, the connection structure (corresponding to the first ridge 33 and the second ridge 34 in the first embodiment, and the groove 62 and the ridge 63 in the second embodiment) increases the rigidity of the connection portion. At the same time, the rigidity is further improved due to the unevenness.

(3) In the cylinder block according to the third aspect, each cylinder liner is connected and connected by a connecting portion having a connecting structure, and a concave portion is formed on an end surface of the connecting portion on the cylinder head side. A cylinder block formed by fitting a fitting portion (a convex portion in the first embodiment) formed on the covering portion. This way,
Connection structure (in the first embodiment, the first ridge 33 and the second
(Corresponding to the groove 62 and the protrusion 63 in the second embodiment), the rigidity of the connecting portion is increased, and the rigidity is further improved due to the unevenness. In addition, the rigidity is improved by the engagement means.

(4) In the cylinder block of at least one of claim 1, claim 3, claim (2) or claim (3), the outer periphery of the concave portion and the fitting portion is formed along the inner peripheral surface of the cylinder liner. A cylinder block characterized by being curved. In this case, the stress around the concave portion and the convex portion can be evenly distributed.

(5) The liner connected body to which the cylinder liner is connected is cast together with the molding of the block main body, and at least the cylinder head side end face of the connecting portion of each of the cylinder liners is covered by the covering portion of the block main body. In the cylinder block, a concave portion communicating with the runner on the crankshaft side is formed on the cylinder head side end surface of the connecting portion of each cylinder liner, and the molten metal is filled into the concave portion through the runner to form a shape corresponding to the concave portion. A cylinder block having a fitting portion.

In this manner, the covering piece is formed integrally with the fitting portion by the molten metal rising in the concave portion, so that the sectional area does not become insufficient, and cracking of the covering piece due to tensile stress is prevented. Further, the covering piece is integrated with the fitting portion, so that the covering piece does not rise from the upper end surface of the connecting portion. Also, it is difficult to form a hot spring.

(6) The liner connected body to which the cylinder liner is connected is formed and cast together with the molding of the block body, and at least the cylinder head side end surface of the connecting portion of each of the cylinder liners is covered with the covering portion of the block body. A method for manufacturing a cylinder block, comprising: forming a coating portion covering a connecting portion of each of the cylinder liners by swelling from a deck surface of the block body; and removing the swelled portion after cooling. Production method. With this configuration, the raised portion is formed in the block body, so that the shrinking force in the central direction is large, and the residual tensile stress of the cylinder block from which the raised portion is removed after curing is reduced, so that the crack is less likely to occur.・ Effective.

[0072]

As described above in detail, according to the first aspect of the present invention, a concave portion is formed on the connecting portion side of the cylinder block, and a fitting portion corresponding to the concave portion is formed on the covering portion side. Since the cross-sectional area of the covering portion that covers the cover is increased, the tensile stress can be dispersed, and cracks in the covering portion due to the stress can be suppressed.

According to the second aspect of the present invention, the connection between the connecting portion and the covering portion covering the connecting portion is engaged by the engaging means, so that separation between them can be prevented. According to the third aspect of the present invention, it is possible to prevent the covering portion from being cracked and to prevent the connecting portion and the covering portion covering the connecting portion from separating.

According to the fourth aspect of the present invention, in addition to the effects of the first aspect of the present invention, a crack is less likely to be formed because a hot junction is less likely to occur and a starting point of a crack is eliminated. In the invention of claim 5, the raised portion is formed in the state of the block coarse material, and the raised portion is removed after cooling, so that the tensile stress of the covering portion covering the connecting portion is reduced, and the crack of the covering portion can be suppressed. it can. According to the sixth aspect of the present invention, the effect of suppressing cracks in the covering portion according to the fifth aspect of the present invention is further enhanced.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a cylinder block according to a first embodiment.

FIG. 2 is an enlarged view of a part X1 in FIG. 1;

FIG. 3 is an exploded plan view of the same cylinder liner.

FIG. 4 is a sectional view taken along the line AA of FIG. 5 in a range of an X1 part of FIG. 1;

FIG. 5 is a side sectional view of the connecting portion.

6 is an enlarged view of a part X3 in FIG. 5;

FIG. 7 is a longitudinal sectional view of a cylinder block.

FIG. 8 is a partial plan view of a cylinder block according to a second embodiment.

FIG. 9 is an enlarged plan view of the connecting portion.

10 is a sectional view taken along line BB of FIG. 11 in the range of FIG. 9;

FIG. 11 is a sectional view taken along line CC of FIG. 8;

FIG. 12 is a sectional view taken along line DD of FIG. 8;

FIG. 13 is a partial plan view of a cylinder block according to a third embodiment.

FIG. 14 is an enlarged view of a Y part in FIG. 13;

FIG. 15 is a partial cross-sectional view showing a state where the casting mold is clamped.

FIG. 16 is a partial cross-sectional view showing a state where a block coarse material is formed using a casting mold.

FIG. 17 is a partial cross-sectional view taken along line EE of FIG. 13;

FIG. 18 is a partial plan sectional view showing a state where the liner main body is set in a casting mold.

FIG. 19 is a partial plan view of a cylinder block according to a fourth embodiment.

FIG. 20 is a partial sectional view of a block coarse material.

FIG. 21 is an explanatory diagram illustrating directions of pulling and shrinking of a molten metal during cooling.

FIG. 22A shows measurement positions I, II, and I shown in FIG.
11 is a graph showing the residual stresses of (A) to (C) of II.

FIG. 23 is a partial plan view of a conventional cylinder block.

24 is a partial longitudinal sectional view taken along line GG of FIG.

FIG. 25 is a partial longitudinal sectional view taken along line HH of FIG. 23;

FIG. 26 is a partial longitudinal sectional view illustrating the flow of molten metal in a conventional cylinder block.

[Explanation of symbols]

15 ... liner connection body, 21, 22, 23, 24 ... cylinder liner, 31 ... first connection part as connection part, 32 ... second connection part as connection part, 33 ... third connection part as connection part,
Reference numeral 34 denotes a fourth connecting portion serving as a connecting portion, 35 denotes a connecting portion serving as a part of the connecting portion, 36 denotes a concave portion, 37 denotes an engaging ridge serving as an engaging means,
38 block main body, 41 covering part, 41a covering piece as covering part, 42 convex part as fitting part, 43 ... engaging groove as engaging means, 45 ... first connecting part as connecting part, 46 ... Second connecting portion as a connecting portion, 47... Third connecting portion as a connecting portion, 4
8: a fourth connecting portion as a connecting portion; 48, a first connecting portion as a part of the connecting portion; 49, a second connecting portion as a part of the connecting portion;
50: a third joining portion which is a part of the connecting portion; 55: a concave portion;
Reference numeral 6 denotes an engaging ridge as an engaging means, 57 a covering portion, 57a a covering piece as a covering portion, 58 a convex portion as a fitting portion, 59 an engaging groove as an engaging means, 62 a concave portion, 63 fitting. Joint part, 75 ... excitement part.

Claims (6)

[Claims] 1. A liner connecting body to which a cylinder liner is connected is molded together with a block main body, and at least a cylinder head side end surface of a connecting portion of each of the cylinder liners is covered by a covering portion of the block main body. A cylinder block, wherein a concave portion is formed in an end surface of a cylinder head side of the connecting portion, and a fitting portion formed in the covering portion is fitted into the concave portion. 2. A liner connected body to which a cylinder liner is connected is cast together with the molding of the block main body, and at least a cylinder head side end face of a connecting portion of each of the cylinder liners is covered with a covering portion of the block main body. A cylinder block, wherein an engagement means for preventing separation between the connection portion and a covering portion covering the connection portion is formed in the cylinder block. 3. The cylinder block according to claim 1, wherein the engagement means is disposed between the recess and the fitting part. 4. The method for manufacturing a cylinder block according to claim 1, wherein a concave portion communicating with a runner on a crankshaft side is formed in an end face on a cylinder head side of a connecting portion of each cylinder liner, and the runner is formed through the runner. A method for manufacturing a cylinder block, characterized in that a recess is filled with molten metal to form a fitting portion, and a cast-in portion of each cylinder liner is formed by molten metal flowing out of the recess. 5. A liner connected body to which a cylinder liner is connected is cast together with the molding of the block main body, and at least a cylinder head side end face of a connecting portion of each of the cylinder liners is covered by a covering portion of the block main body. In the cylinder block, the covering portion covering the connecting portion of each of the cylinder liners is formed by removing a raised portion raised from a deck surface of the block body. 6. A cylinder block according to claim 5, wherein said projecting portion has a mountain-like shape with a larger bulging amount toward a center.