JP2015094261A - Cylinder block and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder block having a lower manufacturing cost for allowing easy molding of a semifinished product of which spiracle machining sites are made thinner by an ordinary casting and molding machine and still greatly reducing a machine working time to form spiracles passing through the molded product, and to provide a method of manufacturing the same.SOLUTION: The cylinder block includes a cylinder forming part 12 and a crank chamber forming part 13, the crank chamber forming part 13 having partition wall portions 18 for partitioning a plurality of crank chambers 14, and spiracle forming portions 20 in which spiracles 41 communicating the adjacent crank chambers 14 with each other are formed by machine work, each of the spiracle forming portions 20 being formed thinner than each of the partition wall portions 18.

Description

  The present invention relates to a cylinder block and a method for manufacturing the same, and more particularly to a cylinder block in which a breathing hole for communicating the crank chambers on both sides with each other is formed in an upper portion of a partition wall that defines a plurality of crank chambers.

  In many cylinder blocks of a multi-cylinder internal combustion engine, a journal portion of a crankshaft is supported by partition portions that define a plurality of crank chambers, and a breathing hole is provided in the partition portion to reduce pumping loss.

  As a cylinder block of such an internal combustion engine, for example, a plurality of cylinders are provided while providing a step between a cylinder wall portion between adjacent cylinders in each bank and a partition wall portion that partitions adjacent cylinders on the lower end side thereof. There is known one in which a breathing hole is formed by drilling on the same plane as the center (see, for example, Patent Document 1).

  Also, the shape of the opening of the breathing hole is an ellipse with a major axis in the direction of maximum load parallel to the axial direction of the cylinder, or a contour in which the breathing hole has two straight portions parallel to the cylinder center plane. (See, for example, Patent Documents 2 and 3).

JP 2009-114985 A JP 05-157005 A JP 2009-275539 A

  However, in the conventional cylinder block and the manufacturing method thereof as described above, if the breathing hole is to be cast in die-cast molding or the like, the stroke of the punch pin becomes large and the mold becomes large. Thus, a normal casting machine could not be used. Therefore, it has been very difficult to cast the breathing hole.

  Also, by providing a stepped wall surface located on one end side of the breathing hole by the lower end of the cylinder wall of the cylinder, the cutting distance of the breathing hole could be reduced to some extent, but the wall thickness (wall thickness) Since the cutting distance on the partition wall side between the large crank chambers is large, the machining time cannot be shortened sufficiently.

  Furthermore, it is desirable to make the breathing hole large to some extent, but when there are a plurality of cylinder rows (banks) such as a V-type engine, the arrangement and casting of the oil passages (lubricating / cooling oil passages) inside them Due to the necessity of securing the hot water around the molten metal at the time of molding, the space for opening the breathing hole is limited, and a small-diameter breathing hole corresponding to each bank is often formed. In that case, the linear motion direction of the crank core that forms the crank chamber at the time of die casting molding and the linear motion direction of the bore pin that forms the bore portion of each cylinder differ depending on the lateral inclination angle of the bank. It was difficult to cast a circular breathing hole without making a cut part. Therefore, it is necessary not only to increase the size of the mold, but also to make the breathing hole irregular by changing the cross-sectional shape of the core pin (non-circular), which is disadvantageous in terms of strength and cost of the core pin.

  The present invention has been made in view of the conventional problems as described above, and can easily form a semi-finished product with a thinned breathing hole processed part using a normal casting machine, and the molded product It is an object of the present invention to provide a cylinder block with a low manufacturing cost and a manufacturing method thereof that can significantly reduce the machining time for forming a breathing hole.

  In order to solve the above problems, the cylinder block according to the present invention includes (1) a cylinder forming portion that forms a plurality of cylinders, and a cylinder forming portion that forms a plurality of crank chambers corresponding to the plurality of cylinders. An integrally formed crank chamber forming portion, and the crank chamber forming portion is adjacent to a partition wall portion defining a pair of crank chambers corresponding to a pair of adjacent cylinders among the plurality of cylinders. A breathing hole forming part in which the breathing holes communicating with each other are formed by machining, and the thickness of the breathing hole forming part is smaller than the thickness of the partition wall part.

  With this configuration, the cutting distance for forming the breathing hole is shortened by the amount that the thickness of the breathing hole forming portion is thinner than the thickness of the partition wall portion. Therefore, the axial length of the breathing hole corresponding to the cutting distance can be sufficiently shortened. Moreover, the entire shape of the cylinder block can be easily formed using a normal casting machine without casting the breathing hole, and the machining time of the breathing hole for the molded product can be greatly shortened. It becomes a cylinder block.

  In the cylinder block of the present invention, (2) the cylinder forming portion may constitute a plurality of banks that form a V-shaped intersection with each other.

  With this configuration, even for a cylinder block of a V-type internal combustion engine, a semi-finished product can be easily formed using a normal casting machine, and machining time for forming a breathing hole through the molded product can be reduced. It can be greatly shortened. Also, the breathing hole can be easily made circular.

  In order to solve the above-described problem, a cylinder block manufacturing method according to the present invention includes (3) a cylinder forming portion that forms a plurality of cylinders, and a crank chamber formation that forms a plurality of crank chambers corresponding to the plurality of cylinders. A partition for partitioning a pair of crank chambers corresponding to a pair of adjacent cylinders among a plurality of cylinders, and a breathing hole for communicating the adjacent crank chambers with each other. A method of manufacturing a cylinder block having a breathing hole forming part, wherein the breathing hole forming part is integrally formed with the breathing hole forming part and the partition wall part of the crank chamber forming part. A thin wall portion corresponding to the hole forming portion and a thick wall portion corresponding to the partition wall portion are formed, and the thin hole portion is machined to form a machined hole that forms a part of the breathing hole. It is.

  With this configuration, a thin-walled portion corresponding to the breathing hole forming portion and a thick-walled portion corresponding to the partition wall portion are formed when casting the semi-finished product, and the thickness of the thin wall portion is thinner than the thickness of the partition wall portion. By shortening the cutting distance for forming the breathing hole by the amount, the cutting distance of the breathing hole can be sufficiently shortened. Moreover, a semi-finished product can be easily molded using a normal casting machine without casting the breathing hole, and the machining time of the breathing hole for the molded product can be greatly shortened. can do.

  According to the present invention, a semi-finished product having a thinned breathing hole machining part is formed using an ordinary casting machine without casting a breathing hole, and machining for forming a breathing hole through the molded product is performed. Since the time can be greatly shortened, it is possible to provide a cylinder block with a low manufacturing cost and a manufacturing method thereof.

It is a principal part expanded sectional view of the cylinder block of the internal combustion engine which concerns on one Embodiment of this invention. It is a principal part schematic sectional drawing at the time of the process of the cylinder block of the internal combustion engine which concerns on one Embodiment of this invention. It is a partial expanded sectional view of the breathing hole vicinity of the cylinder block of the internal combustion engine which concerns on one Embodiment of this invention. 1 is a schematic top view of a cylinder block of an internal combustion engine according to an embodiment of the present invention. It is a VV arrow sectional view of Drawing 4. FIG. 6 is an arrow view in the VI direction of FIG. 5. 7A is an arrow view in the VIIA direction of FIG. 6, and FIG. 7B is an arrow view in the VIIB direction of FIG. It is a principal part schematic sectional drawing at the time of the process of the cylinder block of the internal combustion engine which concerns on other embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(One embodiment)
1 to 7 show a schematic configuration of a cylinder block according to an embodiment of the present invention and a schematic configuration of a part of a casting mold used for manufacturing the cylinder block. The cylinder block of the present embodiment constitutes a main part of an engine block of a V-type multi-cylinder internal combustion engine, for example, a V-type 6-cylinder engine, and is a half formed by die casting which is a kind of casting molding. It is manufactured by machining a product.

  First, the configuration of the present embodiment will be described.

  As shown in FIGS. 1, 4, and 5, the cylinder block 10 of the present embodiment includes an upper cylinder forming portion 12 that forms a plurality of cylinders 11, and a plurality of crank chambers 14 that correspond to the plurality of cylinders 11. The lower crank chamber forming portion 13 is formed.

  The cylinder block 10 is obtained by integrally casting a cylinder forming portion 12 and a crank chamber forming portion 13 by die casting, and is made of, for example, an aluminum alloy.

  As shown in FIGS. 4 to 7, the plurality of cylinders 11 have a plurality of cylinder bores 15 formed in the cylinder forming portion 12, and each cylinder bore 15 is a high-rigidity cylinder liner (not shown) at the time of die casting. Is formed by casting. In each cylinder bore 15, as indicated by a virtual line in FIG. 1, a piston 31 is accommodated so as to be slidable back and forth.

  The cylinder forming unit 12 includes a pair of banks 21A and 21B, each of which forms a plurality of, for example, three cylinders 11 in series (in-line) so as to form substantially the same lateral inclination angle in opposite directions. 21A and 21B form a substantially V shape. Further, oil passages 12w (see FIG. 5) for supplying lubricating / cooling oil to the sliding portions are formed in the vicinity of the substantially V-shaped valley.

  As shown in FIGS. 4 and 6, each of the banks 21 </ b> A and 21 </ b> B includes three cylindrical cylindrical wall portions 22 in which the cylinder liners are cast to form the cylinder bores 15 of the three cylinders 11, and cylinders. A water jacket portion 23 formed around the wall portion 22 and an outer wall portion 24 surrounding the cylindrical wall portion 22 and the water jacket portion 23 are provided. The three cylindrical wall portions 22 of the banks 21A and 21B are integrally coupled to each other at a pair of adjacent portions adjacent to each other.

  As shown in FIGS. 4 and 5, the crank chamber forming portion 13 includes a ceiling wall portion 16 that couples adjacent portions of the pair of banks 21 </ b> A and 21 </ b> B, and outer walls separated from each other of the pair of banks 21 </ b> A and 21 </ b> B. A skirt portion 17 extending obliquely downward from the inner side, and a plurality of, for example, three, inner and lower partition walls 18 that define and form three crank chambers 14 inside the skirt portion 17. ing. The crank chamber forming portion 13 has a breathing hole forming portion 20 in which breathing holes 41 and 42, which will be described later, are formed by machining so that adjacent crank chambers 14 communicate with each other.

  The three crank chambers 14 are positioned below the cylinder bores 15 of each pair of cylinders 11 that are adjacent in the longitudinal direction of the pair of banks 21A and 21B (the axial direction of the journal portion of the crankshaft).

  At least one, for example, two inner partition walls 18 are integrally connected to the outer partition wall 19 via the skirt portion 17, and each pair of cylinders 11 adjacent to each other in the bank longitudinal direction among the plurality of cylinders 11. The journal portion 33 of the crankshaft 32 is rotatably supported between the pair of cylinders 11 while the pair of crank chambers 14 corresponding to the above are partitioned from each other.

  The crankshaft 32 has a plurality of, for example, three crankpins 34 that are equiangularly spaced, for example, and the base ends of a pair of connecting rods 35A and 35B are adjacently coupled to each of the crankpins 34, Each crank pin 34 is connected to journal portions 33 on both sides thereof via crank arms 36A and 36B on both ends of the crank pin 34. Further, the connecting rods 35A and 35B are coupled to the pistons 31 in the two cylinders 11 corresponding to the same crank chamber 14 at the respective leading ends. Then, the pistons 31 in the six cylinders 11 sequentially explode (expand) from the first cylinder C1 to the sixth cylinder C6 shown in FIG. 4, for example, with a phase difference of 120 ° (= 720 ° / number of cylinders). At this time, the crankshaft 32 rotates so as to be able to output rotational power.

  The outer partition wall portion 19 is positioned on both ends of the cylinder block 10 in the axial direction of the journal portion 33 of the crankshaft 32, and rotatably supports the journal portions 33 on both ends of the crankshaft 32.

  The pair of banks 21 </ b> A and 21 </ b> B each extend in a direction parallel to the axis of the journal portion 33 of the crankshaft 32 (hereinafter referred to as the front-rear direction).

  When manufacturing such a cylinder block 10, the entire configuration of the manufacturing equipment is not shown, but as shown in FIGS. 2 and 5, one molding having a crank core 101 corresponding to the shape of the crank chamber forming portion 13. A molded product 10M, which is a semi-finished product (a blank before machining), is formed by using a mold, for example, a fixed mold, and the other mold having a plurality of bore pins 102 corresponding to the shape of the cylinder forming portion 12, for example, a movable mold. Die-cast.

  And a part with high required dimensional accuracy is machined with respect to the molded product 10M, and as shown in FIGS. 3 and 5, a machined hole 41a which is a main part (part) of the breathing holes 41 and 42 is used. 42a are formed to penetrate therethrough.

  That is, as shown in FIG. 6, a pair of crank chambers 14 adjacent to each other with the partition wall 18 therebetween are provided on the upper portions of the inner partition walls 18 adjacent to the cylinder forming portion 12. A pair of breathing holes 41 and 42 are formed so as to communicate with each other on the lower side of the cylinder 11.

  These breathing holes 41 and 42 are mutually arranged on or near two virtual planes P1 and P2 (see FIG. 5; cylinder center arrangement plane) where the central axes of the cylinders 11 of the pair of banks 21A and 21B are arranged. Has been. The plurality of breathing holes 41 formed in the plurality of adjacent inner partition walls 18 are located on the same straight line, and the plurality of breathing holes 42 formed in the plurality of adjacent inner partition walls 18 are The plurality of breathing holes 41 are located on the same straight line parallel to the central axis.

  And the main part of these breathing holes 41 and 42 is circular machined holes 41a and 42a which processed upper part 18a of inner partition part 18 with tool T which is a cutting tool, respectively.

  In the banks 21A and 21B, the central axis positions of the plurality of cylinders 11 in the axial direction of the journal portion 33 of the crankshaft 32 are shifted from each other. The pistons 31 in the pair of cylinders 11 corresponding to the same crank chamber 14 are adjacent to the same crank pin 34 of the crankshaft 32 via connecting rods 35A and 35B as shown in FIG. It is connected.

  The upper portion 18a of the inner partition wall 18 is on one end side in the central axis direction of each of the breathing holes 41, 42, for example, on the right side of the breathing holes 41, 42 in FIGS. 1 and 3, and in the longitudinal direction of each bank 21A, 21B. Are exposed in the radial region of the cylinder bore 15 of one cylinder 11 (for example, the third cylinder C3 of the first cylinder C1 and the third cylinder C3 in FIG. 4) of each pair of cylinders 11 adjacent to each other. The inside of the radial region of the cylinder bore 15 is a region radially inward from the inner peripheral wall surface 15 f of the cylinder bore 15.

  In the present embodiment, the upper portions 18a of the pair of inner partition walls 18 adjacent to each other with the same crank chamber 14 therebetween are spaced apart from each other by an angular interval corresponding to the intersection angle of the banks 21A and 21B. 14 are exposed in the radial region of the cylinder bore 15 of a pair of cylinders 11 (for example, the third cylinder C3 and the fourth cylinder C4 in FIG. 4).

  As shown in FIG. 4, the upper portion 19 a of the outer partition wall portion 19 is partially exposed in the radial region of the cylinder bore 15 of the cylinder 11 located on the end side in the longitudinal direction of the bank 21 </ b> A or 21 </ b> B.

  As shown in FIGS. 4 to 7, a part of the breathing holes 41 and 42 is formed in the upper portions 18 a of the pair of inner partition walls 18 exposed in the pair of cylinder bores 15 corresponding to the same crank chamber 14. The lower stepped wall surface located on the journal portion 33 side in the periphery of the machined holes 41a, 42a on one end side of the breathing holes 41, 42 (see FIG. 7A) with respect to the machined holes 41a, 42a formed. 18c is formed. The journal part 33 side means the bearing surfaces 18b and 19b that hold the journal part 33 in the inner partition part 18 and the outer partition part 19.

  Further, the tool 19 for machining the machined hole 41a or 42a of the breathing hole 41 or 42 also on the upper part 19a of the outer partition wall 19 exposed in the cylinder bore 15 on the longitudinal end side of the bank 21A or 21B. A lower step wall surface 19c (see FIG. 4) located on the journal portion 33 side is formed.

  Here, the lower stepped wall surface 18c is located in the vicinity of the corresponding machining hole 41a or 42a, for example, in the vicinity of the machining hole 41a as shown in FIG. A concave portion 18e having an open concave shape is provided, and both sides of the concave portion 18e are substantially flat as shown in FIG. Although not shown in detail, the lower stepped wall surface 19c also has a concave portion that forms a concave shape that opens upward so as to be positioned closer to the journal portion 33 than the tool T for machining the corresponding machining hole 41a or 42a. The both sides of the concave portion are substantially flat.

  These lower stepped wall surfaces 18c and 19c are substantially formed by partially projecting the lower end surface portion of the bore pin 102 in the vicinity of the inner partition wall portion 18 and the outer partition wall portion 19 in the molded product 10M, as shown in FIG. It is formed at a position in contact with a substantially flat lower end surface 102b and a semi-cylindrical convex surface 102c of a lemon-shaped (cross-sectional shape surrounded by an arc and a chord) 102p.

  More specifically, as shown in FIGS. 3 and 6, in the lower stepped wall surface 18c, the exposed surface main portion 18c1 exposed in the radial region of the cylinder bore 15 has the machining holes 41a and 42a machined. Located below the surface. Further, a peripheral portion 18c2 surrounding the main portion 18c1 is located at substantially the same height as the machining surfaces of the machining holes 41a and 42a.

  Therefore, the main portion 18c1 of the lower stepped wall surface 18c does not come into contact with the tool T during machining of the machining holes 41a and 42a, and remains a cast surface.

  In addition, a substantially semicircular portion 18r adjacent to the moving region of the tool T during machining of the machining holes 41a and 42a in the peripheral portion 18c2 is a substantially semicircular burr-like thin wall that can protrude into the moving region of the tool T. The portion B (the portion where the molten metal has entered the gap between the side wall surface 101e of the crank core 101 and the flat side wall surface 102e of the projecting portion 102p of the bore pin 102) is pushed by the tip of the tool T and dropped off. Yes.

  On the other hand, on the other end side in the central axis direction of each of the breathing holes 41, 42, for example, on the left side of the breathing holes 41, 42 in FIG. 1 and FIG. The upper step wall surface 22d located on the side away from the journal portion 33 in the periphery of the machined holes 41a and 42a (see FIGS. 5 and 7B) is formed.

  The lower step wall surfaces 18c and 19c and the upper step wall surface 22d are curved around the central axis of the machining holes 41a and 42a in the vicinity of the machining holes 41a and 42a, respectively. At the time of die casting, a cast surface is formed by a mold as a part of the surface of the molded product 10M.

  Furthermore, on the other end side of the breathing holes 41 and 42, the other cylinder 11 (for example, the first cylinder C1 and the third cylinder in FIG. 4) of each pair of cylinders 11 adjacent in the longitudinal direction of the banks 21A and 21B. A connecting wall portion 45 is formed below the cylindrical wall portion 22 in the first cylinder C1) of C3 so as to extend to the upper side and both sides of the periphery of the machined holes 41a and 42a of the breathing hole forming portion 20.

  The connecting wall portion 45 has upper regions Z1 and Z2 that are separated from the journal portion 33 in the periphery of the breathing holes 41 and 42 from the lower end of the inner wall portion 22a (inner wall portion) of the cylindrical wall portion 22 (see FIGS. 5 and 7). ), And is formed in a substantially horseshoe shape so as to extend toward the inner partition wall 18 side.

  Further, the connecting wall portion 45 is integrally coupled to the inner partition wall portion 18 on both radial sides that are on both sides of each breathing hole 41, 42 (the left-right direction in FIGS. 7A and 7B). ing.

  More specifically, as shown in FIGS. 1, 3, and 6, the connecting wall portion 45 has a single-side wall surface 45 f separated from the lower step wall surface 18 c from the vicinity of the inner peripheral wall surface 15 f of the cylinder bore 15. It is curved while being inclined toward the wall surface of the inner partition wall 18, and has a shape that reinforces the connecting portion between the cylindrical wall portion 22 between the adjacent cylinder bores 15 and the inner partition wall 18. Further, the connecting wall portion 45 has a region 45a extending on the both sides in the radial direction of the breathing holes 41 and 42 and extending in the direction substantially perpendicular to the axis of the cylinder 11 and the lower side of the cylinder 11 in the axial direction. It is thick near the region 45a. This region 45a is located on the one side in the radial direction of the breathing holes 41 and 42 (on the right side in FIG. 7 (b)) on the lower side in the axial direction of the cylinder 11 (same as the axis of the cylinder 11). The region 45a extends from the lower side in the axial direction of the cylinder 11 to the axis of the cylinder 11 on the other side in the radial direction of the breathing holes 41 and 42 (the left side in FIG. 7B). It spreads greatly in a substantially orthogonal direction (left side in the figure).

  Further, as shown in FIG. 2, the connecting wall portion 45 has a part of the outer peripheral portion on the upper end surface 101 u side of the crank core 101 corresponding to each crank chamber 14 being recessed corresponding to the shape of the connecting wall portion 45. The upper stepped wall surface 22d is formed at a position in contact with the outer protruding portion 101a on the upper end side of the crank core 101.

  As a result, the breathing hole forming portion 20 located on the upper side of the crank chamber forming portion 13 at the stage of the molded product 10M is adjacent to the connecting wall portion 45 having a downwardly concave shape on one side of the pair of adjacent crank chambers 14. In the other pair of adjacent crank chambers 14, a substantially disk-shaped thin portion 18 p is formed adjacent to the upper portion 18 a of the partition wall portion 18 having the upward concave portion 18 e. In the cylinder block 10, machining holes 41a and 42a are formed through the thin portion 18p.

  In addition, the substantially disk-shaped thin portion 18p in the upper portion 18a of the partition wall portion 18 inside the molded product 10M before cutting is formed with the substantially flat outer surface 101b of the outer protrusion 101a on the upper end surface 101u side of the crank core 101. The outer peripheral surface 102d near the substantially lemon-shaped protrusion 102p of the bore pin 102 is formed to be substantially flat.

  The breathing hole forming portion 20 in the cylinder block 10 includes an annular thin portion 20a corresponding to the remaining thin portion 18p remaining in the periphery after the drilling of the machined holes 41a and 42a or an annular support portion supporting the thin portion 18p. The annular thin portion 20a is thinner than the inner partition wall 18. Further, the thickness of the annular thin portion 20a is equal to or less than the thickness of the cylindrical wall portion 22 forming the cylinder bore 15.

  One or the other outer partition wall portion 19 is formed with a thin wall portion (not shown) similar to the thin wall portion 18p at the time of die casting on the central axis of either one of the breathing holes 41 and 42. After the hole 41a or 42a is formed through the hole 41a, the hole 41a or 42a may be closed and then closed by a plug or the like. Alternatively, one or the other outer partition wall portion 19 may have a pair of closed portions that are respectively closed by plugs or the like on the central axis of the breathing holes 41 and 42.

  The plurality of inner partition walls 18 are each formed as a part of the molded product 10M, and then the crank cap 48 is fastened with a plurality of bolts and the bearing surface that holds the journal portion 33 on the center side of the crankshaft 32. 18b has been machined. Similarly, the pair of outer partition walls 19 are respectively formed as part of the molded product 10M, and then bolted to a crank cap (not shown) similar to the crank cap 48, and journals on both ends of the crankshaft 32. The bearing surface etc. which hold | maintain the part 33 are machined.

  Next, the manufacturing method of the cylinder block 10 of this embodiment is demonstrated.

  First, one molding die having a crank core 101 corresponding to the shape of the crank chamber forming portion 13, for example, a fixed die, and the other molding die having a plurality of bore pins 102 corresponding to the shape of the cylinder forming portion 12, for example, a movable die. Is used to die-cast a semi-finished molded product 10M integrally including the cylinder wall portion 22 and the partition walls 18 and 19 of the cylinder 11.

When the molded product 10M is cast and formed, the inner partition 18 that is a thick portion is formed, and the pre-machined breathing hole forming portion 20 that has the thin portion 18p is formed.
As the breathing hole forming part 20 before machining, the thin part 18p corresponding to the processed part of the breathing holes 41, 42 and the periphery of the thin part 18p on one end side of the breathing holes 41, 42 with respect to the thin part 18p Lower step wall surface 18c located on the journal portion 33 side, and upper step located on the side away from the journal portion 33 in the periphery of the thin portion 18p on the other end side of the breathing holes 41 and 42 with respect to the thin portion 18p. A wall surface 22d is formed.

  Next, the machined part of the molded product 10M is machined with high required dimensional accuracy, and the machined holes 41a and 42a, which are the main parts (parts) of the breathing holes 41 and 42, are used with a tool T that is a cutting tool. Form through. That is, the thin-walled portion 18p is machined to form the machined holes 41a and 42a forming part of the breathing holes 41 and 42. As a result, the annular thin portion 20a corresponding to the remaining portion of the thin portion 18p remaining around the machined holes 41a and 42a or corresponding to the annular support portion supporting the thin portion 18p from the periphery. The breathing hole forming part 20 having the above is completed.

  Next, the operation of this embodiment will be described.

  As described above, in the cylinder block 10 of the present embodiment, the upper portion 18a of the partition wall 18 is one cylinder 11 out of a pair adjacent in the front-rear direction on one end side of the breathing holes 41, 42, for example, as shown in FIG. As described above, the first cylinder C1 and the third cylinder C3 are exposed in the radius region of the third cylinder C3. And, by the upper portion 18a of the partition wall portion 18, the machining holes 41a, 42a forming part of the breathing holes 41, 42 are out of the periphery of the machining holes 41a, 42a on one end side of the breathing holes 41, 42. A lower step wall surface 18c located on the journal portion 33 side is formed.

  Therefore, the lower stepped wall surface 18c can be formed as a casting surface during casting of the molded product 10M which is a semi-finished product of the cylinder block 10, and the machined holes 41a and 42a are penetrated into the upper portion 18a of the partition wall portion 18 having a large wall thickness. The machining distance for forming is shortened by the lower step wall 18c. That is, the machining time of the machining holes 41a and 42a in the breathing holes 41 and 42 can be sufficiently shortened by the amount that the thickness of the breathing hole forming portion 20 is thinner than the thickness of the inner partition wall portion 18. it can.

  Moreover, the semi-finished molded product 10M in which the breathing hole machining part is thinned can be easily molded using an ordinary die-cast molding machine without casting the breathing holes 41 and 42, and the molded product 10M Since the processing time of the breathing holes 41 and 42 can be greatly shortened, the manufacturing cost of the cylinder block 10 can be reduced.

  In the present embodiment, the cylinder forming portion 12 forms the upper step wall surface on the side away from the journal portion 33 around the machining holes 41a and 42a on the other end side of the breathing holes 41 and 42. . Therefore, the total length of the machining holes 41a and 42a is shortened by the lengths of the lower step wall surface 18c and the upper step wall surface at both ends, and the machining distance and machine of the machining holes 41a and 42a are reduced. Processing time can be greatly reduced.

  Moreover, since the thin-walled portion 18p, which is a cutting part of the machined holes 41a and 42a, can be flattened into a substantially disk shape at the stage of forming the semi-finished product 10M, the biting property of the tool T during the cutting process. As a result, the machining time can be shortened.

  Furthermore, on the other end side of the breathing holes 41 and 42 in the cylinder forming portion 12, the other cylinder 11, for example, the first cylinder C1 and the third cylinder C3 shown in FIG. Of these, the partition wall portion 18 passes through the upper region Z1 or Z2 (see FIG. 7B) away from the journal portion 33 in the periphery of the breathing hole 41 or 42 from the lower end of the inner wall portion 22a of the cylindrical wall portion 22 in the first cylinder C1. A connecting wall portion 45 extending to the side is formed.

  Therefore, the wall thickness in the vicinity of the breathing holes 41 and 42 is increased, and the stress concentration in the vicinity of the breathing holes 41 and 42 is suppressed.

  In addition, in the present embodiment, the connecting wall portion 45 is integrally coupled to the partition wall portion 18 on both radial sides of the breathing holes 41 and 42 in the direction orthogonal to the central axis of the cylinder 11. , 42 in the vicinity of the breathing holes 41, 42, the wall thickness in the vicinity of the breathing holes 41, 42 is increased in a wide range in the upper region Z 1, Z 2, and stress concentration in the vicinity of the breathing holes 41, 42 is effectively suppressed.

  Further, the lower step wall surface 18c and the upper step wall surface 22d are cast surface surfaces formed so as to be bent around the central axis of the machining holes 41a and 42a in the vicinity of the machining holes 41a and 42a. Therefore, the wall thickness in the vicinity of the breathing holes 41 and 42 is sufficiently ensured, and the undulations of the wall surface therefor are formed with a gently curved casting surface, and the stress concentration in the vicinity of the breathing holes 41 and 42 is reduced. More effectively suppressed.

  Further, the lower step wall surface 18c has a concave portion 18e that forms a concave shape of an upper opening so as to be positioned closer to the journal portion 33 than the machining holes 41a and 42a in the vicinity of the machining holes 41a and 42a. Therefore, the upper portion 18a of the partition wall portion 18 is securely coupled to the cylindrical wall portion 22 of the one cylinder 11, and the wall thickness in the vicinity of the breathing holes 41 and 42 is sufficiently secured.

  Although the cylinder block 10 is for a V-type engine, the entire shape of the molded product 10M, which is a semi-finished product, can be easily formed using a normal casting machine, and the breathing holes 41 and 42 are formed in the molded product 10M. The machining time for penetrating and forming can be greatly shortened, and the breathing holes 41 and 42 can be easily made circular.

  Thus, in the present embodiment, the molded product 10M, which is a semi-finished product of the cylinder block 10, can be easily molded using a normal casting machine without casting the breathing holes 41 and 42, and the molded product. The machining time for penetrating and forming the breathing holes 41 and 42 for 10M can be greatly shortened. As a result, the cylinder block 10 with a low manufacturing cost can be provided.

  Moreover, in the manufacturing method of the cylinder block 10 of the present embodiment, when the molded product 10 which is a semi-finished product is die-cast, the lower step wall surface 18c and the upper step wall surface 22d The thin portion 18p located between them is formed. Therefore, the cutting distance of the machining hole can be sufficiently shortened by shortening the cutting distance in the upper part of the partition wall portion 18 having a large wall thickness by the lower step wall surface 18c and the upper step wall surface 22d. . Moreover, the molded product 10M can be easily molded using a normal casting machine without casting the breathing holes 41 and 42, and the machining time of the machined holes 41a and 42a for the molded product 10M can be greatly reduced. The cylinder block 10 with low manufacturing cost can be manufactured.

(Other embodiments)
FIG. 8 shows a schematic cross-sectional view of a main part during machining of a cylinder block of an internal combustion engine according to another embodiment of the present invention. The cylinder block 10 of the present embodiment is substantially the same as the cylinder block 10 of the above-described embodiment, but the shape of the semi-finished product at the stage of the molded product 10M is different. Therefore, the same configuration as that of the above-described embodiment will be described using the same reference numerals as the corresponding components of the embodiment shown in FIGS. 1 to 7, and the differences from the embodiment will be described below. Explained.

  As shown in FIG. 8, when manufacturing the cylinder block 10 of the present embodiment, as in the case of the embodiment, one mold having a crank core 101 corresponding to the shape of the crank chamber forming portion 13, for example, a fixed Using a mold and the other mold having a plurality of bore pins 102 corresponding to the shape of the cylinder forming portion 12, for example, a movable mold, a molded product 10M which is a semi-finished product is die-cast.

  However, in the present embodiment, the shapes of the crank core 101 and the plurality of bore pins 102 are different from those of the above-described embodiment.

  Specifically, the lower step wall surfaces 18c and 19c are substantially semi-cylindrical shapes in which the lower end surface portion of the bore pin 102 is partially protruded in the vicinity of the inner partition wall portion 18 and the outer partition wall portion 19 in the molded product 10M. Is formed at a position in contact with the substantially flat lower end surface 112b and the semi-cylindrical convex surface 112c.

  Corresponding to the substantially semi-cylindrical protruding portion 112p of the bore pin 102, the crank core 101 side is also located above the side wall surface 101e and on the upper side wall surface 111f, and the side wall surface 111f is separated from the side wall surface 111f. A stepped wall surface 111g connected to the side wall surface 111e in contact with the portion 18 is provided.

  In this case, the peripheral portion 18c2 on the lower step wall surface 18c can be eliminated. In addition, the substantially semi-circular burr-like thin portion B does not protrude into the moving region of the tool T, and the substantially flat lower end surface 112b and the semi-finished wall surface 111g of the crank core 101 and the protruding portion 112p of the bore pin 102 Although the thin wall portion in which the molten metal has entered the gap between the cylindrical convex surfaces 112c can remain after the die casting, it becomes a thin film shape orthogonal to the central axis of the cylinder 11, so that the crank chamber side or the cylinder bore 15 side Can be removed and deburred easily.

  A substantially disk-shaped thin portion 18p in the upper portion 18a of the partition wall portion 18 inside the molded product 10M corresponding to the portions of the machined holes 41a and 42a before cutting is an outer protrusion on the upper end surface 101u side of the crank core 101. The substantially flat outer surface 101b of 101a and the outer peripheral surface 112d in the vicinity of the substantially cylindrical protrusion 112p of the bore pin 102 are formed to be substantially flat.

  Also in the present embodiment, the molded product 10M, which is a semi-finished product of the cylinder block 10, can be easily molded using an ordinary casting machine without casting the breathing holes 41 and 42, and the molded product 10M is breathed. The machining time for penetrating the holes 41 and 42 can be greatly reduced. As a result, the cylinder block 10 with a low manufacturing cost can be provided.

  In each of the above-described embodiments, the internal combustion engine is a V-type 6-cylinder engine. However, the present invention can also be applied to other V-type engines having different numbers of cylinders, and a multi-cylinder other than the V-type. It can also be applied to an internal combustion engine.

  Further, in each of the above-described embodiments, the draft at the time of die casting is not particularly mentioned, but it is needless to say that an appropriate draft can be set at the formation surface of the casting surface.

  Further, the lower step wall surfaces 18c and 19c and the upper step wall surface 22d are cast surfaces that are curved around their central axes in the vicinity of the machining holes 41a and 42a, respectively, but are not necessarily curved. Alternatively, a concave portion with an upper opening or a lower opening may be formed so as to have a substantially rectangular cross section with rounded corners or a polygonal cross section.

  As described above, the present invention can easily mold a semi-finished product using a normal casting machine without casting a breathing hole, and machine processing for forming a breathing hole through the molded product. Since the time can be greatly shortened, it is possible to provide a cylinder block with a low manufacturing cost and a manufacturing method thereof. The present invention as described above is useful for a cylinder block in which a breathing hole for communicating the crank chambers on both sides thereof is formed in the upper part of a partition wall section defining a plurality of crank chambers, and a manufacturing method thereof in general.

  DESCRIPTION OF SYMBOLS 10 ... Cylinder block, 10M ... Molded product (semi-finished product), 11 ... Cylinder, 12 ... Cylinder formation part, 12w ... Oil path, 13 ... Crank chamber formation part, 14 ... Crank chamber, 15 ... Cylinder bore, 15f ... Inner peripheral wall surface (Radius region), 16 ... ceiling wall part, 17 ... skirt part, 18 ... inner partition part, 18a ... upper part, 18b and 19b ... bearing surface, 18c ... lower stepped wall surface, 18c1 ... main part, 18c2 ... surroundings Part, 18e ... concave part (part of the lower stepped wall surface), 18p ... thin wall part (respiratory hole machining part, machined hole cutting part), 18r ... substantially semicircular part, 19 ... outer partition wall part 19a ... upper part, 19c ... lower stepped wall surface, 20 ... breathing hole forming part, 21A, 21B ... bank, 22 ... cylindrical wall part, 22a ... inner wall part (inner wall part), 22d ... upper stepped wall surface, 23 ... Water jacket, 4 ... Outer wall portion, 31 ... Piston, 32 ... Crankshaft, 33 ... Journal portion, 34 ... Crankpin, 35A, 35B ... Connecting rod, 36A, 36B ... Crank arm, 41, 42 ... Breathing hole, 41a, 42a ... Machining Hole 45 ... Connecting wall portion 45a ... Line 45f ... Wall surface 48 ... Crank cap 101 ... Crank core 101a ... External projection 101b ... Outer surface 101e ... Side wall surface 101u ... Upper end surface 102 ... Bore pin, 102b ... lower end surface, 102c ... convex surface, 102d ... outer peripheral surface, 102e ... side wall surface, 102p ... projection, 111e ... side wall surface, 111f ... side wall surface, 111g ... stepped wall surface, 112b ... lower end surface, 112c ... convex surface, 112d ... outer peripheral surface, 112p ... protrusion, C1 ... first cylinder, P1, P2 ... virtual plane (cylinder center arrangement surface), Z1, 2 ... upper region

Claims (3)

A cylinder forming part for forming a plurality of cylinders;
A crank chamber forming portion formed integrally with the cylinder forming portion so as to form a plurality of crank chambers corresponding to the plurality of cylinders,
The crank chamber forming portion is formed by machining to form a partition wall defining a pair of crank chambers corresponding to a pair of adjacent cylinders of the plurality of cylinders, and a breathing hole communicating the adjacent crank chambers with each other. A breathing hole forming part,
A cylinder block, wherein the breathing hole forming portion is formed thinner than the partition wall.   2. The cylinder block according to claim 1, wherein the cylinder forming portion forms a plurality of banks that intersect each other in a V shape. A cylinder forming part that forms a plurality of cylinders, and a crank chamber forming part that forms a plurality of crank chambers corresponding to the plurality of cylinders, wherein the crank chamber forming part is a pair of adjacent cylinders A method of manufacturing a cylinder block having a partition wall section defining a pair of crank chambers corresponding to a cylinder, and a breathing hole forming section in which a breathing hole for communicating adjacent crank chambers is formed.
When casting a semi-finished product integrally having the breathing hole forming part and the partition part of the crank chamber forming part,
A thin portion corresponding to the breathing hole forming portion;
Forming a thick part corresponding to the partition part,
A method of manufacturing a cylinder block, wherein the thinned portion is machined to form a machined hole that forms a part of the breathing hole.

Images