Manufacturing method of cylinder block

Abstract

This allows for securing space for the placement of the cast-out pins. [Solution] The cylinder block 10 has fastening bosses 11 to which external parts are attached. The fastening bosses 11 are boss holes 11H that extend inward from the side surface of the cylinder block 10 and divide the boss hole 11H having a fitting portion 11Ha into which external parts are inserted and an extension portion 11b that extends from the fitting portion 11Ha. The manufacturing method of the cylinder block 10 involves placing a cooling pin CP, which is a cast-out pin configured to be coolable, at a position corresponding to the boss hole 11H and performing casting.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cylinder block.

Background Art

[0002] It is known to use cooling pins, which are casting pins configured to be cooled, in the casting of cylinder blocks. The cooling pins have internal flow paths for a cooling medium such as cooling water. By flowing the cooling medium through the flow paths, the cooling pins are cooled (see, for example, Patent Document 1).

[0003] The cooling pins are arranged, for example, at locations where the cylinder block is to be hollowed out. By performing cooling through the cooling pins, the occurrence of casting defects such as shrinkage cavities in the cylinder block can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] It is necessary to provide a plurality of fastening bosses on the cylinder block. The fastening bosses are structures for attaching external components to the cylinder block and have holes extending from the outer surface of the cylinder block toward the inside. As the cylinder block is downsized along with the downsizing of the engine, when arranging the fastening bosses, it has become difficult to secure space for arranging the cooling pins in some cases.

Means for Solving the Problems

[0006] A method for manufacturing a cylinder block that solves the above problems is a method for manufacturing a cylinder block using casting, wherein the cylinder block has a fastening boss to which an external component is attached, and the fastening boss is a boss hole extending inward from the side surface of the cylinder block, and the boss hole has a fitting portion into which the external component is inserted and an extension portion extending from the fitting portion, and a cast-out pin configured to be coolable is placed at a position corresponding to the boss hole and casting is carried out. [Effects of the Invention]

[0007] This method of manufacturing the cylinder block promotes cooling during casting even within a limited area, thereby suppressing the occurrence of casting defects. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows a portion of the side structure of the cylinder block. [Figure 2] Figure 2 shows the manufacturing process of a cylinder block. [Modes for carrying out the invention]

[0009] An embodiment of a method for manufacturing a cylinder block will be described with reference to the drawings. Figure 1 shows a part of the side structure of the cylinder block 10, and Figure 2 shows the manufacturing process of the cylinder block 10 using the cross-sectional structure of the cylinder block 10 along line 2-2 in Figure 1 and the mold 20 used to manufacture the cylinder block 10.

[0010] The cylinder block 10 constitutes, for example, an inline four-cylinder engine. The cylinder block 10 has a cylinder bore (not shown), a water jacket 15, an upper mounting portion 16, etc., as cast-out holes opening on its upper surface. The cylinder block 10 also has a bearing portion 14 that functions as a crankshaft bearing, a lower mounting portion 17, etc., as recesses or cast-out holes opening on its lower surface. The cylinder head is attached to the upper mounting portion 16 using fixing members such as bolts. A member having a crankshaft bearing structure, such as a bearing cap, is attached to the lower mounting portion 17 using fixing members such as bolts.

[0011] The cylinder block 10 further has a plurality of fastening bosses 11. The fastening bosses 11 are structures for attaching external components such as auxiliary equipment to the outer surface of the cylinder block 10. The fastening bosses 11 define boss holes 11H that extend inward from the side surface of the cylinder block 10. External components are attached to the cylinder block 10 by inserting them into the boss holes 11H. The external components include the equipment to be attached and fastening members such as bolts for securing such equipment.

[0012] The mold 20 comprises a fixed mold 22 and a movable mold 21. The movable mold 21 faces the fixed mold 22 and moves away from the fixed mold 22 when the mold is opened. The mold 20 may further include one or more movable cores 23 that move in a direction different from the movable mold 21. The cylinder block 10 is cast by pouring molten metal material into the cavity 20C, which is partitioned inside the mold 20 by clamping, and allowing it to cool and solidify. Aluminum alloy or cast iron can be used as the metal material. In the parts of the cylinder block 10 that will become the casting holes, components such as casting pins and cores that protrude from the mold 20 into the cavity 20C are placed. Note that, for convenience, these components are not shown in Figure 2.

[0013] For example, the movable mold 21 defines the portion of the cavity 20C corresponding to the upper surface of the cylinder block 10, and the fixed mold 22 defines the portion of the cavity 20C corresponding to the lower surface of the cylinder block 10. The movable core 23 defines the portion of the cavity 20C corresponding to the side surface of the cylinder block 10. However, the mold 20 is not limited to this configuration and should be configured to form a cylinder block 10 of a desired shape.

[0014] The manufacturing method of the cylinder block 10 in this embodiment uses a cooling pin CP, which is a cast-out pin configured to be coolable, in the casting process. The cooling pin CP has a flow path for a cooling medium such as cooling water inside. The cooling pin CP is cooled by the flow of the cooling medium through this flow path. For example, the cooling pin CP is connected to a cooling medium supply unit 30, and the supply unit 30 supplies the cooling medium to the cooling pin CP according to the temperature of the cooling pin CP or its surroundings. Note that the structure of the cooling pin CP and the method of controlling the cooling of the cooling pin CP are not limited as long as the cooling pin CP is configured to be coolable.

[0015] The cooling pin CP is positioned at a location corresponding to the fastening boss 11. In other words, during the casting process, the cooling pin CP is inserted into the boss hole 11H. The cooling pin CP only needs to be positioned for at least some of the multiple fastening bosses 11. The fastening boss 11 on which the cooling pin CP is positioned is the target fastening boss 12.

[0016] In at least one of the multiple fastening bosses 11, the target fastening boss 12 has a boss hole length D1 greater than the length D2 required for inserting the external component. In other words, the boss hole 11H extends from the side of the cylinder block 10, through the portion that functions effectively in the fitting between the external component and the fastening boss 11, into the interior of the cylinder block 10. That is, the boss hole 11H of the target fastening boss 12 consists of a fitting portion 11Ha into which the external component is inserted, and an extension portion 11Hb that extends further from the fitting portion 11Ha. The fitting portion 11Ha is a through hole that opens to the side of the cylinder block 10. The length of the fitting portion 11Ha is length D2.

[0017] The above length D2 is, for example, the minimum depth of the pilot hole required for fastening between an external component and the fastening boss 11, and is a length including the effective length of the screw and the clearance in the external component. The length D1 of the boss hole 11H is, for example, 1.5 times or more the length D2, and may be 2.0 times or more the length D2. Also, the maximum diameter of the extended portion 11Hb may be smaller than the maximum diameter of the fitting portion 11Ha.

[0018] When viewed from the side surface of the cylinder block 10, that is, from a position facing the opening surface of the boss hole 11H, the target fastening boss 12 is preferably arranged at the central portion in the vertical direction, and is preferably arranged at the central portion in the left - right direction orthogonal to the vertical direction. At least one target fastening boss 12 is preferably arranged at the central portion in the vertical direction and at the central portion in the left - right direction when viewed from a position facing the side surface of the cylinder block 10.

[0019] <The operation and effect of this embodiment> According to the manufacturing method of this embodiment, since the fastening boss 11 is used as the location for arranging the cooling pin CP, even in the cylinder block 10 with limited physical space, the cooling during casting is promoted by the cooling pin CP, and it is possible to suppress casting defects such as shrinkage cavities. And since the boss hole 11H of the target fastening boss 12 is composed of the fitting portion 11Ha and the extended portion 11Hb, the cooling pin CP can be inserted deeper compared to the case where the boss hole 11H consists only of the fitting portion 11Ha. Therefore, it is possible to promote cooling in a wider range.

[0020] Furthermore, by arranging the target fastening boss 12 at the central portion of the cylinder block 10, it is possible to achieve both the suppression of casting defects by promoting efficient cooling using the cooling pin CP and the accurate mounting of external components.

[0021] <Modification example> The above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0022] · In addition to the position corresponding to the boss hole 11H of the target fastening boss 12, the cooling pins CP may also be arranged at positions different from the positions where the fastening bosses 11 are provided. · The engine constituted by the cylinder block 10 is not limited to an in-line four-cylinder engine, and may be an engine with various cylinder arrangements such as an in-line three-cylinder engine, a V-type six-cylinder engine, etc. The shapes and arrangements of the components other than the above-mentioned target fastening boss 12 in the cylinder block 10, such as the cylinder bore and the water jacket, are arbitrary.

Explanation of Reference Numerals

[0023] CP... Cooling pin, 10... Cylinder block, 11, 12... Fastening boss, 11H... Boss hole, 11Ha... Fitting portion, 11Hb... Extended portion, 20... Mold, 21... Movable mold, 22... Fixed mold, 23... Movable core, 30... Supply portion.

Claims

[Claim 1] A method for manufacturing a cylinder block using casting, The cylinder block has fastening bosses to which external components are attached, The fastening boss is a boss hole extending inward from the side surface of the cylinder block, and the boss hole has a fitting portion into which the external component is inserted and an extension portion extending from the fitting portion, Casting is carried out by placing a cast-out pin, configured to be coolable, at a position corresponding to the boss hole. A method for manufacturing a cylinder block.

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