JP2012246831A - Cooling structure for internal combustion engine, cylinder block, and method for manufacturing cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure for an internal combustion engine that can improve cooling effect around a coolant path which is formed as a branch path which is branched off from a coolant jacket in cast parts, in the internal combustion engine including cast parts subjected to impregnation processing in bodies, and to provide the cylinder block and a method for manufacturing the cylinder block.SOLUTION: Inter-bore cooling channels 22 are formed in inter-cylinder bore regions 21 in the cylinder block 11. The cylinder block 11 is cast and subsequently subjected to resin impregnation processing. Thus, resin which is impregnated into the molded nest 27 and cured seals a leakage path formed of the molded nest 27. A resin film 50 which is formed by the resin impregnation processing is removed from an inner circumferential surface of the inter-bore cooling channels 22. A metal material of the cylinder block 11 is exposed on the inner circumferential surface.

Description

  The present invention relates to a cooling structure for an internal combustion engine in which a cooling fluid passage branched from a cooling fluid jacket is formed in a cast part constituting a main body of the internal combustion engine such as a cylinder block, a cylinder block, and a method for manufacturing the cylinder block.

  For example, in Patent Documents 1 and 2, an inter-bore cooling water passage (cooling fluid passage) that branches from a water jacket (cooling fluid jacket) is formed between cylinder bores of cylinders arranged in series in a bank of an internal combustion engine. A cooling structure for an internal combustion engine is disclosed in which the cooling performance of the internal combustion engine is improved by flowing a coolant (cooling water) through the cooling water passage. In Patent Document 1, the amount of coolant flowing between cylinder bores is adjusted according to the combustion timing between cylinders. In Patent Document 2, in particular, in order to ensure the roundness of the cylinder bore, the flow rate of the coolant flowing between all the cylinder bores is increased to enhance the cooling effect in the area between all the cylinder bores.

  Moreover, main body parts, such as a cylinder block which comprises the main body of an internal combustion engine, are normally manufactured by die-casting (for example, aluminum die-casting). In this type of die-casting part, it is inevitable that a casting hole (a small bubble group) is generated with a certain probability. For example, if there is a cast hole between cylinder bores in a cylinder block, there is a possibility that a leak path is formed by a cast hole connecting the cooling water channel between the bores to the cylinder liner interface (interface between the cylinder block and the cylinder liner). Then, the coolant leaks from the leak path through the cylinder liner interface into the combustion chamber and the crankcase, which may cause engine malfunction.

  For this reason, resin impregnation processing is performed on die-cast parts such as cylinder blocks in order to seal a leak path due to a cast hole (for example, Patent Documents 3 to 5). In resin impregnation processing, impregnation treatment in which die cast casting parts such as cylinder blocks are immersed in resin liquid under reduced pressure and impregnated with resin liquid in the casting cavity, and after draining and washing, the resin liquid impregnated in the casting cavity is cured. A hardening process (for example, thermosetting) is performed, and a leak path by a cast hole is sealed.

JP 2007-247523 A (5th and 6th pages, FIGS. 2, 3 and 5) Japanese Patent Laying-Open No. 2005-325712 (Pages 4, 5 and FIGS. 3 and 4) JP 7-216411 A JP-A-5-237726 JP 2002-011563 A

  By the way, in an engine equipped with a supercharger, the combustion chamber temperature tends to be relatively high during engine operation. For this reason, the interbore cooling water passage that passes through the region between the cylinder bores functions effectively in enhancing the cooling effect. However, conventionally, a resin film left by the resin impregnation process is formed on the inner peripheral surface of the cooling water channel between the bores. This resin film has a lower thermal conductivity than a metal such as aluminum, which is a material for forming a cylinder block, and iron (cast iron), which is a material for forming a cylinder liner. For this reason, even if it is a comparatively thin resin film, the heat | fever of the area | region between cylinder bores is hard to be transmitted to a cooling water, and causes the cooling effect of the area | region between cylinder bores to fall. In particular, the area between the cylinder bores is considerably narrow and the cooling water passage between the bores is also very thin (for example, 0.5 to 3 mm in diameter). Therefore, the flow rate of the coolant flowing through the cooling water passage between the bores is relatively small, and There is a request to increase the cooling effect as much as possible. In addition, in order to improve the cooling performance of the predetermined part of the internal combustion engine body in addition to the inter-bore cooling water passage, there is a similar request for other coolant passages formed by branching from the water jacket.

  The present invention has been made in order to solve the above-described problems, and an object thereof is an internal combustion engine including an impregnated cast part in a main body as a branch branched from a coolant jacket to the cast part. An object of the present invention is to provide a cooling structure for an internal combustion engine, a cylinder block, and a method for manufacturing the cylinder block, which can enhance the cooling effect around the formed coolant passage.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to a first aspect of the present invention, in a liquid-cooled internal combustion engine having at least one bank in which a plurality of cylinders are arranged in series, a coolant provided so as to surround a plurality of cylinder bores forming the plurality of cylinders. A cooling structure for an internal combustion engine having a jacket, wherein the main body of the internal combustion engine includes a cast part in which at least a part of the coolant jacket is formed, and the cast part serves as a branch of the coolant jacket. A cooling liquid passage is provided, an impregnation treatment for impregnating an impregnation liquid made of an organic material or an inorganic material, and a curing treatment for curing the impregnation liquid are performed, and at least one of the inner peripheral surfaces of the cooling liquid passage is provided. The gist of the part is that the impregnating material formed by curing the impregnating liquid is removed and the forming material of the cast part is exposed.

  According to this configuration, a cooling fluid passage serving as a branch of the cooling fluid jacket is provided in the cast part that constitutes the main body of the internal combustion engine and in which at least a part of the cooling fluid jacket is formed. Furthermore, the casting part having the cooling liquid passage is subjected to an impregnation treatment for impregnating an impregnation liquid made of an organic material or an inorganic material and a curing treatment for curing the impregnation liquid after the impregnation treatment. The leak path by the generated casting hole is sealed with the impregnating material (the impregnating liquid is hardened). Further, the impregnating material is removed from at least a part of the inner peripheral surface of the coolant passage of the cast part, and the forming material (metal material) of the cast part is exposed. That is, an impregnation material (for example, an organic material film or an inorganic material film) that prevents heat conduction does not exist on at least a part of the inner peripheral surface of the coolant passage. For this reason, the heat transferred from the cylinder (combustion chamber) to the cast part during the operation of the internal combustion engine is quickly conducted on at least a part of the inner peripheral surface of the coolant passage, and is efficiently transferred to the coolant in the coolant passage. Communicated. Therefore, the cooling effect around the coolant passage formed as the branch of the coolant jacket in the internal combustion engine including the cast part subjected to the impregnation process can be enhanced.

According to a second aspect of the present invention, in the cooling structure for an internal combustion engine according to the first aspect, the coolant passage is an inter-bore coolant passage formed between the cylinder bores.
According to this configuration, the heat of the portion between the cylinder bores is quickly conducted to at least the portion of the inner peripheral surface of the inter-bore coolant passage (coolant passage) where the impregnating material has been removed, and the inter-bore coolant passage Heat transfer to the inside coolant is performed efficiently. For this reason, the part between each cylinder bore can be cooled efficiently.

According to a third aspect of the present invention, in the cooling structure for an internal combustion engine according to the first or second aspect, the coolant passage is a straight hole.
According to this configuration, since the coolant passage is a straight hole, the removal tool is easily inserted into the coolant passage to remove the impregnating material from the inner peripheral surface.

According to a fourth aspect of the present invention, in the internal combustion engine cooling structure according to any one of the first to third aspects, at least a part of the inner peripheral surface of the coolant passage is polished.
According to this configuration, since at least a part of the inner peripheral surface of the coolant passage is polished, the desired impregnating material can be obtained without removing most of the forming material (metal material) of the cast part as compared with cutting. Can be selectively removed.

  The invention according to claim 5 is a cylinder block constituting a main body of the internal combustion engine, and the cylinder block is a cast part in the cooling structure of the internal combustion engine according to any one of claims 1 to 4. It is composed.

According to this configuration, it is possible to increase the cooling efficiency by the coolant flowing through the coolant passage while sealing the leak route caused by the cast hole generated along with the casting of the cylinder block.
The invention according to claim 6 comprises a main body of a liquid-cooled internal combustion engine having at least one bank in which a plurality of cylinders are arranged in series, and is provided so as to surround a plurality of cylinder bores forming the plurality of cylinders. A method of manufacturing a cylinder block having a coolant jacket, wherein the cylinder block having the coolant jacket is cast and a coolant passage serving as a branch of the coolant jacket is provided in the cylinder block. A manufacturing process for manufacturing, an impregnation process for impregnating the cylinder block with an impregnation liquid composed of an organic material or an inorganic material, a curing process for curing the impregnation liquid impregnated in the cylinder block, and an inner peripheral surface of the cooling liquid passage The impregnating material formed by curing the impregnating liquid is removed from at least a part of A removal step of exposing the formed material of the block, further comprising a a gist.

  According to this method, in the manufacturing process, the cylinder block is manufactured in a form in which a cooling liquid passage serving as a branch of the cooling liquid jacket is provided with casting in a form having a cooling liquid jacket. At this time, the coolant passage may be formed, for example, by casting using a core, or may be formed by processing (for example, drilling) the cylinder block after casting. In the impregnation step, the cylinder block is impregnated with an impregnation liquid made of an organic material or an inorganic material. As a result, the impregnating liquid is impregnated into the cast hole in the cylinder block. In the curing step, the impregnating liquid impregnated in the cylinder block is cured. At this time, the impregnation liquid impregnated in the casting hole is cured, thereby sealing the leakage path by the casting hole. Further, the entire surface of the cylinder block including the inner peripheral surface of the coolant passage and the inner peripheral surface of the coolant jacket is covered with an impregnation material (for example, a film) formed by curing the impregnation liquid. In the removing step, the impregnating material is removed from at least a part of the inner peripheral surface of the coolant passage, and the cylinder block forming material (metal material) is exposed to the at least part. For this reason, it is possible to enhance the cooling effect of the peripheral portion of the coolant passage provided as a branch of the coolant jacket, while sealing the leak route caused by the cast hole generated with the casting of the cylinder block.

  A seventh aspect of the present invention is the cylinder block manufacturing method according to the sixth aspect, wherein the manufacturing step includes a casting step of casting the cylinder block and the cooling in a region between the cylinder bores in the cylinder block. A passage forming step of forming an inter-bore coolant passage as a liquid passage by drilling.

  According to this method, the cylinder block having the coolant jacket is cast in the manufacturing process. In the passage forming step, an inter-bore coolant passage as a coolant passage is formed by drilling in a region between the cylinder bores in the cylinder block. Since the coolant passage between the bores is drilled, the mold apparatus can have a simple structure as compared with the case where the coolant passage is formed by casting using a core. In addition, since the drilled coolant passage between the bores is a straight hole, when the removal tool is inserted into the coolant passage between the bores in the removal process, the removal tool is not evenly contacted or biased against the inner peripheral surface. The impregnating material can be removed with little pressing. During operation of the internal combustion engine, the heat in the region between the cylinder bores is efficiently conducted to at least the portion of the inner peripheral surface of the inter-bore coolant passage where the impregnating material has been removed, and the coolant in the inter-bore coolant passage. Therefore, the portion between each cylinder bore can be efficiently cooled.

According to an eighth aspect of the present invention, in the cylinder block manufacturing method according to the sixth or seventh aspect, in the removing step, an inner peripheral surface of the coolant passage is polished.
According to this method, in the removing step, the impregnated material formed on the inner peripheral surface of the coolant passage is removed by polishing. Since it is polishing, the impregnating material is scraped off from the surface side little by little. For this reason, compared with cutting, the target impregnating material can be selectively removed while suppressing the removal amount of the forming material of the cylinder block to zero or as little as possible.

  A ninth aspect of the present invention is the method of manufacturing a cylinder block according to the eighth aspect, wherein in the removing step, abrasive particles are attached to a cylindrical fibrous portion provided on a rotating shaft. And inserting the fibrous portion having an outer diameter substantially the same as the inner diameter of the coolant passage into the coolant passage while rotating the rotating shaft of the polishing tool. To polish.

  According to the method, in the removing step, the inner diameter of the coolant passage is rotated while rotating the rotating shaft using a polishing tool in which abrasive grains are attached to a cylindrical fibrous portion provided on the rotating shaft. By inserting fibrous portions having substantially the same outer diameter into the coolant passage, the interior of the coolant passage is polished and the impregnating material is removed. Even if the coolant passage has a relatively small diameter such as a drill hole, the impregnation material in the coolant passage can be removed while being relatively simple and suppressing the removal amount of the forming material of the cylinder block to zero or as little as possible.

1 is a perspective view of an engine to which an internal combustion engine cooling structure in one embodiment is applied. The top view of a cylinder block. Sectional drawing of the engine in the AA line in FIG. The flowchart which shows the manufacturing method of a cylinder block. (A)-(c) The schematic cross section which shows the formation method of the cooling water channel between bores. (A)-(f) The schematic diagram which shows the manufacturing method of a cylinder block. Sectional drawing which shows the grinding | polishing process of the cooling water channel between bores. (A) Cross-bore cooling water channel in polishing process, (b) Cross sectional view showing cooling water channel between bores after polishing.

An embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, an engine 10 as an internal combustion engine includes a cylinder block 11 and a cylinder head 12. The engine 10 of the present embodiment is a multi-cylinder engine having a bank in which a plurality (N) of cylinders # 1 to #N (four cylinders # 1 to # 4 in the example of FIG. 1) are arranged in series. In the bank of the cylinder block 11, a plurality of (for example, four) cylinder bores 13 forming the cylinders # 1 to # 4 are provided in a state of being arranged in series.

  As shown in FIGS. 1 and 2, the cylinder block 11 has a block-side water that is a portion on the cylinder block 11 side of a water jacket 14 as a coolant jacket having a shape surrounding the periphery of the plurality of cylinder bores 13. A jacket 15 is formed. Furthermore, the cylinder block 11 is provided with an inlet 16 for introducing cooling water from the outside into the block-side water jacket 15. In this embodiment, an open deck type in which the block-side water jacket 15 is opened on the deck surface 17 located on the cylinder head 12 side is employed as the cylinder block 11. The cylinder head 12 is formed with a head-side water jacket 28 (see FIG. 3) that communicates with the block-side water jacket 15 and constitutes the water jacket 14 together with the block-side water jacket 15.

  The cylinder block 11 is made of aluminum or aluminum alloy, and is manufactured by die casting. A cylindrical cylinder liner 18 made of, for example, cast iron is cast on the inner peripheral portion of the bore of the cylinder block 11, and a cylinder bore 13 is formed inside the cylinder liner 18. In the present embodiment, the cylinder block 11 corresponds to a cast part that constitutes the main body of the internal combustion engine.

  As shown in FIG. 1, a part of the coolant (here, coolant) introduced into the block-side water jacket 15 from the inlet 16 provided on the cylinder # 1 side in the cylinder block 11 is block-side water. The jacket 15 flows along the arrangement of the cylinder bores 13 to the cylinder # 4. Further, as shown by an arrow S at the upstream position of the cylinder # 1 from the block-side water jacket 15, a part of the coolant that has risen toward the cylinder head 12 moves downstream in the cylinder head 12 (rightward in FIG. 1). Flowing. The coolant that has risen toward the cylinder head 12 as indicated by the arrow T from the block-side water jacket 15 at the downstream side of the cylinder # 4 and the coolant that has flowed downstream in the cylinder head 12 merge to form the radiator side. Is discharged. Such a coolant flow is generated by driving a coolant pump (here, a water pump) (not shown).

  Between the two adjacent cylinder bores 13 of the N (four in this example) cylinder bores 13 arranged in series, a total (N-1) (for example, three) inter-cylinder bore region 21 exists. To do. The inter-cylinder bore region 21 is a region sandwiched between two adjacent cylinder bores 13 and 13 and is likely to be heated to a high temperature. Therefore, each inter-cylinder bore region 21 has an inter-bore cooling water passage 22 as an inter-bore coolant passage. Is provided. In addition, the area | region 21 between cylinder bores in this embodiment points out the casting part among the cylinder bores 13. FIG. For this reason, in the cylinder block 11 of this example having the cylinder liner 18, the inter-cylinder bore region 21 refers to a region between the outer peripheral surfaces of the adjacent cylinder liners 18.

  Each cylinder bore 13 is for accommodating a piston in a reciprocable manner. The space above each piston in each cylinder bore 13 constitutes a part of a combustion chamber for burning a fuel / air mixture. The adjacent cylinder bores 13 and 13 are close to each other, and the interval is, for example, about 4 to 8 mm.

  During operation of the engine 10, the air-fuel mixture explodes and burns in the combustion chamber, and heat is generated accordingly. This heat raises the temperature around the combustion chamber. Since the space above the piston in the cylinder liner 18 forms a combustion chamber, the upper portion of the cylinder liner 18 is particularly hot.

  In the inter-cylinder bore region 21, a hole communicating from the deck surface 17 to the block-side water jacket 15 is opened with a tool such as a drill, and the drill bore (usually referred to as “drill path”) forms an inter-bore cooling water passage 22. ing. The inter-bore cooling water passage 22 is formed by an oblique path extending in a direction orthogonal to the cylinder arrangement direction while inclining with respect to the bore axis direction (direction perpendicular to the paper in FIG. 2) in the inter-cylinder bore region 21. In this embodiment, the plurality of inter-bore cooling water passages 22 are all formed to have the same diameter D. Of course, the cooling water channel 22 between the bores may have a plurality of different diameters D. Further, the interbore cooling water passage 22 is provided at a position corresponding to an upper portion of the cylinder liner 18 that is particularly hot in the height direction of the cylinder block 11.

  Next, the inter-bore cooling water passage 22 and the surrounding structure will be described. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, that is, a cross-sectional view in which a region between cylinder bores is cut in a direction orthogonal to the cylinder arrangement direction. Here, since the inter-bore cooling water passages 22 have basically the same structure, the inter-bore cooling water passages 22 formed in the inter-cylinder bore region 21 between the cylinders # 2 and # 3 will be described below.

  In the cross section shown in FIG. 3, a pair of block-side water jackets 15 are positioned on both sides in the arrangement direction of the cylinder bores 13 (see FIG. 2) (both left and right sides in FIG. 3). In FIG. 3, assuming that the space between the pair of block-side water jackets 15 is the inner side, one end portion (left end portion in FIG. 3) of the interbore cooling water passage 22 is one on the deck surface 17 of the cylinder block 11 (left side in FIG. 3). The block side water jacket 15 opens at a position near the inside of the opening. The inter-bore cooling water channel 22 extends substantially linearly in an oblique direction that is displaced in both the bore axial direction (downward in FIG. 3) and the direction orthogonal to the cylinder arrangement direction (left-right direction in FIG. 3). ing. The opposite end (the right end in FIG. 3) of the interbore cooling water passage 22 communicates with the other (the right side in FIG. 3) block-side water jacket 15. Since the interbore cooling water passage 22 of this embodiment is a drill hole, it extends in a straight line.

  As shown in FIG. 3, the engine 10 is joined by fastening bolts 29 with the cylinder block 11 and the cylinder head 12 sandwiching the gasket 25 disposed on the deck surface 17 of the cylinder block 11. It is constituted by. A through hole 25 a is formed in the gasket 25 at a position corresponding to the opening on the head side (left side in FIG. 3) of the inter-bore cooling water passage 22. The cylinder head 12 is formed with a communication hole 12a that opens at a position corresponding to the through hole 25a and a head-side water jacket 28 that communicates with the communication hole 12a. The communication hole 12a is formed with the same diameter as the diameter D (see FIG. 2) of the inter-bore cooling water passage 22, or a larger diameter or a slightly smaller diameter. Therefore, other than the arrows S and T in FIG. 1, the coolant flows from the block-side water jacket 15 to the head-side water jacket 28 (FIG. 3) through the inter-bore cooling water passages 22 in the cylinder bore regions 21. It is like that.

  Then, in FIG. 3, the coolant 21 flows between the right block side water jacket 15 through the inter-bore cooling water passage 22 and the head side water jacket 28 through the through hole 25a and the communication hole 12a, whereby the cylinder bore region 21 is cooled. . For this reason, the temperature around the cylinders # 1 to # 4 during the operation of the engine 10 is suppressed to be lower than the assumed reference temperature.

  As shown in FIG. 5, in the die-cast cast cylinder block 11, a plurality of minute bubbles generated by entraining air bubbles in the process of press-fitting molten metal (aluminum combined financial liquid) into a mold. There is a possibility that there is a cast hole 27 that is a gathering. This type of casting hole 27 may cause a leakage path of the coolant.

  As shown in FIG. 5, the inter-bore cooling water passage 22 is formed so as to pass through the center of the width of the inter-cylinder bore region 21, but it does not deviate in the cylinder arrangement direction (the left-right direction in FIG. 5) within the processing tolerance. Inevitable. For example, when the formation position of the inter-bore cooling water passage 22 deviates by a distance within the machining tolerance in the cylinder arrangement direction with respect to the center of the width of the inter-cylinder bore region 21, the inner circumference of the cylinder block 11 on the cylinder bore 13 side on the deviated side The surface, that is, the interface between the cylinder block 11 and the cylinder liner 18 (hereinafter referred to as “liner interface 26”) and the inter-bore cooling water passage 22 approach each other.

  In this case, if there is a cast hole 27 between the inter-bore cooling water channel 22 and the liner interface 26 on the approaching side, there is a possibility that a leak path due to the cast hole 27 is formed in the inter-bore cooling water channel 22 and the liner interface 26. is there. For this reason, the cylinder block 11 after die casting is subjected to resin impregnation processing (organic impregnation processing) in order to impregnate the casting cavity 27 with synthetic resin and seal the leak path.

  In the cylinder bore region 21 of the present embodiment, the width of the narrowest portion is a value within a range of 2 to 6 mm, for example. The diameter D of the cooling water passage 22 between the bores is the minimum distance (for example, 0) required for the strength (thickness) between the cooling water passage 22 between the bores and the liner interface 26 even when the processing tolerance is shifted to the maximum. .. value in the range of 2 to 0.5 mm) or more. In this example, the inter-bore cooling water channel 22 has a diameter D within a range of 0.5 to 3 mm, for example. The interbore cooling water passage 22 of this example has a diameter D that is not more than half the width of the narrowest portion of the inter-cylinder bore region 21. Of course, if the required strength is ensured, a diameter D exceeding half the width of the narrowest portion can be adopted.

  When this kind of resin impregnation processing is performed, as shown in FIG. 5B, the leakage path by the casting cavity 27 is sealed because the casting cavity 27 is filled with the resin, but the cooling water channel 22 between the bores in the cylinder block 11 is sealed. The entire surface including the inner peripheral surface and the inner peripheral surface of the block-side water jacket 15 is coated with a resin film 50, for example. The resin film 50 is formed by non-uniform film thickness because the resin liquid remaining on the cylinder block 11 after the liquid drainage treatment or post-cleaning is performed after the impregnation treatment.

  Therefore, in the heat conduction path from the heat generated in the combustion chambers of the cylinders # 1 to # 4 from the liner interface 26 to the inner peripheral surface (coolant interface) of the interbore cooling water passage 22 through the cylinder bore region 21. The resin (resin film 50) formed on the inner peripheral surface of the inter-bore cooling water channel 22 causes a significant decrease in thermal conductivity. For example, the thermal conductivity of a thermosetting resin (impregnating material) is about 0.15 (W / m · K), and the thermal conductivity of an aluminum alloy (for example, ADT4) is about 96 (W / m · K). For this reason, in this embodiment, this type of resin film 50 is removed from the inner peripheral surface of the inter-bore cooling water channel 22.

<Manufacturing method>
Next, a method for manufacturing the cylinder block 11 will be described. FIG. 4 is a flowchart showing each process when the cylinder block 11 is manufactured. Hereinafter, the manufacturing method of the cylinder block 11 will be described with reference to FIGS.

  First, in step S1, die casting of the cylinder block 11 is performed (casting step). The cylinder block 11 has a structure in which a cylinder liner 18 is cast. In die casting, a cylinder liner 18 is press-fitted and held in a liner holder provided on one of a pair of molds (a fixed mold and a movable mold), and a gap is formed between the liner holder and the cylinder liner 18 in a clamped state. In this state, the molten metal is poured into the cylinder liner outer peripheral cavity, and after solidification, the mold is opened and the cylinder block 11 is removed from the mold.

  In the next step S2, a hole communicating with the block-side water jacket 15 is formed in a portion corresponding to the cylinder bore region 21 on the deck surface 17 of the cylinder block 11 by a drilling process using a drill device, and a drill path is formed by the hole. An inter-bore cooling water passage 22 is formed (passage forming step). In the present embodiment, the manufacturing process includes steps S1 and S2.

  FIG. 5A shows a cross section of the inter-cylinder bore region 21 in which the inter-bore cooling water channel 22 formed by a drill pass is formed after die casting. As shown in FIG. 5A, a large number of constricted (mushroom-shaped) protrusions 18a are formed on the outer peripheral surface of the cylinder liner 18 over almost the entire area. 18a is engaged with the cylinder block 11 by meshing. In the example shown in FIG. 5A, a cast hole 27 is formed between the inter-bore cooling water channel 22 and the liner interface 26 in the inter-cylinder bore region 21, and the cast hole 27 may become a coolant leakage path. There is.

  Returning to FIG. 4, in the next step S3, pre-cleaning is performed. That is, as shown in FIG. 6A, the plurality of cylinder blocks 11 are stored in the basket 31, and the plurality of cylinder blocks 11 are pre-cleaned by immersing the basket 31 in the cleaning liquid 33 in the liquid tank 32. .

  In the next step S4, pressure reduction is performed. That is, as shown in FIG. 6B, a basket 31 containing a plurality of cylinder blocks 11 is housed in a decompression tank 35 and sealed with a lid, and the inside of the decompression tank 35 is decompressed in this sealed state.

  In the next step S5, resin impregnation is performed. That is, as shown in FIG. 6C, a resin liquid 36 (impregnation liquid) in an amount that allows the entire cylinder block 11 to be immersed in the decompression tank 35 in a decompressed state is poured. The resin liquid 36 in this example is made of a thermosetting resin liquid before curing. Since the resin liquid 36 is poured under reduced pressure, the resin liquid 36 is impregnated into the pores such as the cooling water passage 22 between the bores of the cylinder block 11 and the casting cavity 27. In addition, after pouring the resin liquid 36 as needed, you may perform pressure reduction further.

  When the resin impregnation is completed, in the next step S6, the basket 31 taken out from the decompression tank 35 is accommodated in the centrifuge 37, and the liquid is removed by a centrifuge action (FIG. 6 (d)). As a result, the excess resin liquid 36 adhering to the surface of the cylinder block 11 (including the concave portion and the inner peripheral surface of the hole) is removed.

  In the next step S7, post-cleaning is performed. That is, as shown in FIG. 6 (e), by immersing a basket 31 containing a plurality of cylinder blocks 11 after resin impregnation and draining in a cleaning liquid 39 in a liquid tank 38, the plurality of cylinder blocks 11 are Wash. In the present embodiment, the processes of steps S3 to S7 correspond to an impregnation step.

  In the next step S8, heat treatment is performed. That is, as shown in FIG. 6 (f), a plurality of cylinder blocks 11 housed in the basket 31 are immersed in hot water 41 of the heating tank 40, and the resin liquid impregnated in the cylinder block 11 is thermally cured (curing step). ). In the heating tank 40, the temperature of the hot water 41 is controlled to a set temperature equal to or higher than the thermosetting temperature of the resin liquid. In the state where the resin impregnation process including the resin impregnation process and the heat treatment (thermosetting process) is finished, as shown in FIG. 5B, the resin liquid impregnated in the casting cavity 27 is cured, and the cooling water channel between the bores A leak path by the cast hole 27 between the liner 22 and the liner interface 26 is sealed. At this time, a resin film 50 (impregnating material) made of a cured resin is formed on the entire surface of the cylinder block 11 including the inner peripheral surface of the inter-bore cooling water passage 22. The resin film 50 has a thickness in the range of 20 to 200 μm, for example. The resin film 50 is relatively thin, and even if the resin film 50 remains, the necessary flow path diameter of the interbore cooling water path 22 is ensured. For this reason, conventionally, the manufacture of the cylinder block 11 has been completed through the steps up to here. Although not shown in FIGS. 5B and 5C, the resin film 50 is also formed on the deck surface 17.

  In the present embodiment, in step S9, the resin in the inter-bore cooling water channel 22 is removed (removal step). In this embodiment, the polishing tool 51 shown in FIGS. 7 and 8A is used as the removal tool, and the resin film 50 is removed by polishing the inner peripheral surface of the interbore cooling water channel 22. Here, the polishing is adopted because the resin film 50 can be scraped off little by little from the surface side, and the removal amount of the metal (for example, aluminum alloy) which is a forming material of the cylinder block 11 is suppressed to zero or as little as possible while the resin is removed. This is because the film 50 can be selectively removed.

  As shown in FIGS. 7 and 8A, the polishing tool 51 used in this embodiment has a large number of thread-like portions 53 extending radially from the rotary shaft 52 in a predetermined region on the tip side of the rotary shaft 52. In addition, it has a cylindrical fibrous portion 55 in which a spherical polishing body 54 is provided at the tip of each thread-like portion 53. The polishing tool 51 is formed by attaching abrasive grains of a predetermined size almost on one surface to the surface of the fibrous portion 55 (that is, the surface of the polishing body 54). As the polishing tool 51, a tool having a fibrous portion 55 having an outer diameter substantially the same as the inner diameter of the interbore cooling water passage 22 is used. At the time of polishing operation, the base of the rotating shaft 52 of the polishing tool 51 is mounted on the chuck portion of a drill device (not shown), and the drill device is driven to rotate the rotating shaft 52 as shown in FIG. The fibrous portion 55 is reciprocated in the axial direction in a state where the fibrous portion 55 is inserted into the interbore cooling water passage 22. As a result, as shown in FIG. 8B, the resin film 50 in the interbore cooling water channel 22 is removed by polishing. For this reason, the inner peripheral surface of the inter-bore cooling water channel 22 is in a state in which the metal (aluminum alloy in this example) that is a material for forming the cylinder block 11 is exposed. In the present embodiment, the resin film 50 is removed in the entire longitudinal direction of the interbore cooling water passage 22.

  Here, the abrasive of the fibrous portion 55 of the polishing tool 51 is easier to grind the resin that is the forming material of the resin film 50 than the metal (aluminum alloy) that is the forming material of the cylinder block 11. For this reason, even if the metal (aluminum alloy) is locally exposed at the end of the polishing process, the removal amount of the metal to be ground is several at most before the polishing of the entire inner peripheral surface of the inter-bore cooling water channel 22 is finished. It can be suppressed to μm or less.

  The cylinder block 11 manufactured by the above manufacturing method is assembled in a state where the crankshaft is supported by the crankcase, and a plurality of pistons each having a connecting rod connected to the crankshaft are accommodated in each cylinder bore 13. The The engine 10 is manufactured by assembling the cylinder head 12 to the deck surface 17 of the cylinder block 11 via the gasket 25. In the engine 10, the block-side water jacket 15 and the head-side water jacket 28 communicate with each other via an inter-bore cooling water passage 22 that passes through each cylinder-bore region 21, a through-hole 25 a, and a communication hole 12 a.

<Action>
Next, the operation of the engine 10 provided with the cylinder block 11 will be described.
During the operation of the engine 10, a coolant pump (water pump) is driven, and coolant is introduced from the inlet 16 shown in FIG. A part of the coolant introduced from the introduction port 16 ascends from the block side water jacket 15 to the cylinder head 12 side as shown by an arrow S in FIG. To the right). The other coolant flows downstream in the block-side water jacket 15 and rises from the downstream position to the cylinder head 12 side as indicated by an arrow T to move downstream in the head-side water jacket 28 (FIG. 1). The cooling water that has flowed in the right direction) is merged and discharged to the radiator side.

  For example, in the engine 10 equipped with a supercharger (not shown), the combustion chambers of the cylinders # 1 to # 4 tend to be relatively hot. However, in the engine 10 of the present embodiment, the inter-cylinder bore regions 21 are cooled by the coolant flowing through the inter-bore cooling water passages 22 formed in the inter-cylinder bore regions 21. The resin film 50 is removed from each of the cooling water passages 22 between the bores, and the metal material (aluminum or aluminum alloy in this example) of the cylinder block 11 is exposed on the inner peripheral surface thereof. For this reason, the heat transferred from the combustion chamber to the inter-cylinder bore region 21 via the cylinder liner 18 is quickly conducted to the inner peripheral surface of the inter-bore cooling water channel 22 and flows from the inner peripheral surface through the inter-bore cooling water channel 22. It is efficiently transmitted to the coolant. As a result, the cooling effect of the inter-cylinder bore region 21 by the coolant flowing through the inter-bore cooling water passage 22 is enhanced, and the inter-cylinder bore region 21 is suppressed to a reference temperature or lower.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) The resin film 50 formed as a result of the resin impregnation process is removed on the inner peripheral surface of the inter-bore cooling water passage 22 formed in the state communicating with the block-side water jacket 15 in the inter-cylinder bore region 21. As a result, in the cylinder block 11, the resin film 50 of the low thermal conductivity material is eliminated from the inner peripheral surface of the inter-bore cooling water channel 22 while sealing the leak path by the casting cavity 27 between the inter-bore cooling water channel 22 and the liner interface 26. be able to. For this reason, heat is easily transferred from the cylinder block 11 to the coolant in the inter-bore cooling water passage 22, and the cooling performance of the inter-cylinder bore region 21 can be enhanced. Accordingly, the inter-cylinder bore region 21 can be effectively cooled by the coolant flowing through the inter-bore cooling water passage 22. For example, the temperature around the cylinders # 1 to # 4 during the operation of the engine 10 can be suppressed below an assumed reference temperature.

  (2) Since polishing is employed to remove the resin film 50, the unnecessary resin film 50 can be removed while maintaining the inner diameter of the inter-bore cooling water channel 22 substantially as designed. Moreover, since it is grinding | polishing, the resin film 50 is scraped off little by little from the surface side. On the other hand, when the cutting which removes the resin film 50 using a cutting tool such as a drill is adopted, there is a possibility that the forming material (for example, aluminum alloy) of the cylinder block 11 which is the base of the resin film 50 is excessively shaved. For this reason, by polishing, it is possible to selectively remove only the resin film 50 to be removed while suppressing the removal amount of the forming material of the cylinder block 11 to zero or as small as possible compared to cutting.

  (3) A polishing tool 51 having a structure in which abrasive grains are attached to the surface of a cylindrical fibrous portion 55 provided on the rotating shaft 52 was used. In particular, in this example, a structure in which abrasive grains are attached to the surface of a cylindrical fibrous portion 55 in which a spherical abrasive 54 is fixed to the tip of a thread-like portion 53 extending radially from the rotating shaft 52 is used. . The fibrous portion inserted into the inter-bore cooling water channel 22 while rotating the rotating shaft 52 using the polishing tool 51 having the diameter D of the inter-bore cooling water channel 22 and the fibrous portion 55 having substantially the same diameter. The inner peripheral surface of the cooling water channel 22 between the bores is polished by reciprocating 55 in the axial direction (that is, the water channel axis direction), and the resin film 50 is removed. Since the rotary polishing tool 51 is such, the inside of the inter-bore cooling water passage 22 can be uniformly polished in the circumferential direction, and the inner circumference of the inter-bore cooling water passage 22 can be obtained by reciprocating the polishing tool 51 in the axial direction. The surface can be evenly polished in the axial direction. As a result, the resin film 50 can be removed substantially uniformly in a desired region in the longitudinal direction (the entire region in this example) in the inter-bore cooling water channel 22. For example, in the case of a polishing tool having a polishing portion only on one side, the polishing portion hits the inner peripheral surface of the inter-bore cooling water channel 22 and the hitting portion is preferentially polished. In this case, the resin film 50 is removed unevenly and a part thereof remains, or the inner peripheral surface of the inter-bore cooling water passage 22 is excessively shaved, and the aluminum alloy that is a forming material of the cylinder block 11 is scraped unnecessarily. Worry about inconvenience. However, in the present embodiment, the spherical polishing body 54 easily hits the inner peripheral surface of the inter-bore cooling water passage 22 evenly in the circumferential direction, and uniform polishing of the resin film 50 is easy to achieve. For this reason, it is easy to avoid leaving the resin film 50 and excessive scraping of the forming material of the cylinder block 11. Therefore, it is possible to cleanly remove the resin film 50 having low thermal conductivity while keeping the inner diameter of the inter-bore cooling water passage 22 appropriately.

  (4) Since the resin film 50 disappears from the inner peripheral surface of the inter-bore cooling water passage 22 and the metal material is exposed, heat from the combustion chamber side is conducted through the region 21 between the cylinder bores and the inner peripheral surface of the inter-bore cooling water passage 22 ( The thermal conductivity up to the coolant interface is improved. For this reason, the cooling effect of the area 21 between cylinder bores increases, and also in the high output type engine 10, the area 21 between cylinder bores can be hold | maintained below reference temperature. As a result, for example, thermal deterioration of the rubber under the gasket 25 can be suppressed, and occurrence of thermal deformation (out of roundness) of the cylinder bore 13 can be prevented.

  (5) Since the cooling water channel 22 between the bores is a drill hole, it extends linearly. For this reason, the rotary polishing tool 51 into which the cylindrical fibrous portion 55 is inserted can be used. For example, if the cooling water channel between the bores to be polished is bent, even if the polishing tool 51 is used, a part hitting part or a part that is biased is generated, and the resin film 50 can be uniformly removed due to this. Disappear. However, according to the present embodiment, since the interbore cooling water passage 22 is a straight hole, when the fibrous portion 55 of the polishing tool 51 is inserted, the inner peripheral surface is less likely to hit or be biased. The resin film 50 can be removed almost uniformly without bias.

  (6) The cylinder block 11 having the block-side water jacket 15 is manufactured by die casting (casting step (S1)), and the interbore cooling water passage 22 is formed by drilling in the subsequent passage formation step (S2). For this reason, compared with the case where the cooling water channel 22 between the bores is formed by casting, the die device for die casting is relatively simple in structure and operation because the core (for example, the core pin) is unnecessary. be able to.

  (7) Since the resin film 50 is removed only in the inter-bore cooling water passage 22, it is necessary as compared with the case where at least a part of the resin film formed on the surface of the cylinder block 11 other than the inter-bore cooling water passage 22 is removed together. The removal process can be completed relatively easily by keeping the removal area of the resin film as small as possible while ensuring the cooling effect.

The embodiment described above may be modified as follows.
The inter-bore cooling water passage 22 may not be provided in all of the plurality of inter-cylinder bore regions 21, for example, in the configuration of N cylinders # 1 to #N, only one of the (N-1) inter-cylinder bore regions 21 or The configuration in which the inter-bore cooling water channel 22 is provided in only two or only (N−2) may be employed.

  Polishing in the coolant passage is not limited to the method using the polishing tool 51. Sand blasting may be employed in which a relatively fine grain sand is allowed to flow in the coolant passage and the resin film is removed by polishing.

  -Removal of the resin film (impregnating material) in the coolant passage is not limited to polishing but may be cutting. For example, the resin film 50 may be removed by inserting a drill having the same diameter as the drill used when forming the coolant passage into the coolant passage. In this case, it is preferable to perform the cutting process under a condition that the cutting resistance with respect to the forming material (for example, aluminum alloy) of the cylinder block 11 is larger than the cutting resistance with respect to the resin film 50. Alternatively, the resin film 50 may be removed by etching using an etching solution that dissolves the resin but does not dissolve the metal.

  -The casting part which comprises the main body of an internal combustion engine is not limited to the cylinder block 11, The cylinder head 12 may be sufficient. In this case, a cooling fluid passage (an interbore cooling water passage) may be provided in a region between the cylinder bores of the cylinder head 12 and the same processing (impregnation processing and polishing processing in the cooling fluid passage) may be performed.

  The cooling fluid passage is not limited to the inter-bore cooling water passage 22. A coolant passage formed as a branch of the water jacket 14 may be formed in a portion other than the region between the cylinder bores in the cylinder block 11 or the cylinder head 12. Further, it is not essential that the coolant passage as a branch formed in the cylinder block communicates with the block-side water jacket 15. For example, the coolant passage communicates with the head-side water jacket 28 in the assembled state as the engine 10. It may be configured.

  Instead of the configuration in which the resin film 50 is removed in the entire length direction of the inter-bore cooling water channel 22, only a part of the resin film in the entire length direction of the inter-bore cooling water channel 22 may be removed. For example, the resin film may be removed from only a part of the inter-bore cooling water passage 22 that is likely to contribute to improvement of heat conduction. For example, a configuration in which at least one end of both ends of the inter-bore cooling water channel 22 is not polished (removed) may be employed. This is because the block-side water jacket 15 and the communication hole 12a are located in the vicinity of both end portions of the inter-bore cooling water passage 22 so that a relatively high cooling effect can be obtained.

  -You may remove together the resin film 50 formed in parts other than the internal peripheral surface of the cooling water channel 22 between bores. For example, as a part other than the cooling water passage 22 between the bores, other branches and a part or all of the inner peripheral surface of the block-side water jacket 15 can be cited, and these resin films 50 may be removed together. .

  The inter-bore cooling water channel 22 is not limited to being composed of one hole, and may be configured by crossing two holes. For example, in FIG. 3, a hole that is bilaterally symmetrical (that is, the inclination is opposite) in the inter-bore cooling water channel 22 is added to cross the inter-bore cooling water channel 22.

The polishing tool 51 used in the removing step (polishing step) may have a configuration in which abrasive grains are attached to the surface of a spiral brush (fibrous portion) wound around the tip of the rotating shaft 52, for example.
-The cylinder liner 18 may be press-fitted into the cylinder block instead of the cast hole. Further, the present invention may be applied to a linerless engine.

  The coolant passage is not limited to a hole formed in a cast part such as the cylinder block 11. For example, a slit-like groove may be formed between adjacent cylinder bores 13 on the deck surface 17 of the cylinder block 11, and an inter-bore cooling water channel may be constituted by this groove.

  The impregnation process is not limited to the organic impregnation process using an organic material such as a resin liquid, and an inorganic impregnation process using an inorganic material may be adopted. An example of a material used in the inorganic impregnation process is water glass. In this case, in the removing step, the cured water glass film formed on the inner peripheral surface of the inter-bore cooling water channel 22 may be removed by polishing using, for example, a polishing tool. The cooling effect of the region 21 between the cylinder bores can be enhanced by removing the water glass film having a lower thermal conductivity than the forming material (metal) of the cylinder block 11. Of course, sandblasting, etching, cutting, or the like may be employed to remove the water glass film.

  -The number of internal combustion engine banks is not limited to one. An engine having at least one bank may be used. For example, it may be employed in a V-type multi-cylinder engine having two banks. It can also be used in engines with more than two banks. When the coolant passage is provided in the inter-cylinder bore region 21, it is preferable that the engine has two or more cylinders in one bank.

  DESCRIPTION OF SYMBOLS 10 ... Engine as an internal combustion engine, 11 ... Cylinder block as a casting part which comprises the main body of an internal combustion engine, 12 ... Cylinder head, 13 ... Cylinder bore, 14 ... Water jacket as a coolant jacket, 15 ... Block side water jacket, DESCRIPTION OF SYMBOLS 16 ... Introduction port, 17 ... Deck surface, 18 ... Cylinder liner, 21 ... Area between cylinder bores, 22 ... Cooling fluid passage and cooling water passage between bores as cooling fluid passage between bores, 25 ... Gasket, 26 ... Liner interface, 27 ... Cast hole, 28 ... head side water jacket, 36 ... resin liquid as impregnating liquid, 50 ... resin film as impregnating material, 51 ... polishing tool as removal tool, 52 ... rotating shaft, 53 ... thread-like part, 54 ... Abrasive body, 55 ... Fibrous part, # 1 to # 4 ... Cylinder, S1 ... Casting process constituting manufacturing process, S2 ... Manufacturing process That path forming step, S3 to S7 ... impregnation step, S8 ... curing step, S9 ... removing step.

Claims (9)

In a liquid-cooled internal combustion engine having at least one bank in which a plurality of cylinders are arranged in series, an internal combustion engine cooling structure having a coolant jacket provided so as to surround a plurality of cylinder bores forming the plurality of cylinders There,
The main body of the internal combustion engine includes a cast part in which at least a part of the coolant jacket is formed. The cast part is provided with a coolant passage serving as a branch of the coolant jacket, and is made of an organic material or an inorganic material. An impregnation treatment for impregnating the impregnation liquid made of the material and a curing treatment for curing the impregnation liquid are performed, and at least a part of the inner peripheral surface of the cooling liquid passage is formed by curing the impregnation liquid. A cooling structure for an internal combustion engine, wherein the impregnating material is removed and the forming material of the cast part is exposed. The internal combustion engine cooling structure according to claim 1,
The cooling structure for an internal combustion engine, wherein the coolant passage is an inter-bore coolant passage formed between the cylinder bores. The cooling structure for an internal combustion engine according to claim 1 or 2,
The cooling structure for an internal combustion engine, wherein the coolant passage is a straight hole. The internal combustion engine cooling structure according to any one of claims 1 to 3,
The cooling structure for an internal combustion engine, wherein at least a part of an inner peripheral surface of the coolant passage is polished. A cylinder block constituting a main body of an internal combustion engine,
A cylinder block comprising the cast part in the cooling structure for an internal combustion engine according to any one of claims 1 to 4. A block-side coolant jacket provided so as to surround a plurality of cylinder bores forming a plurality of cylinder bores, comprising a main body of a liquid-cooled internal combustion engine having at least one bank in which a plurality of cylinders are arranged in series. A cylinder block manufacturing method comprising:
A manufacturing process of casting the cylinder block having the coolant jacket and manufacturing the cylinder block in a form in which a coolant passage serving as a branch of the coolant jacket is provided;
An impregnation step of impregnating the cylinder block with an impregnation liquid made of an organic material or an inorganic material;
A curing step of curing the impregnating liquid impregnated in the cylinder block;
Removing the impregnating material formed by curing the impregnating liquid from at least a part of the inner peripheral surface of the coolant passage to expose the forming material of the cylinder block to the at least part;
A method of manufacturing a cylinder block, comprising: It is a manufacturing method of the cylinder block according to claim 6,
The manufacturing process includes
A casting process for casting the cylinder block;
A passage forming step of forming an inter-bore coolant passage as a coolant passage by drilling in a region between cylinder bores in the cylinder block;
A method of manufacturing a cylinder block, comprising: In the manufacturing method of the cylinder block of Claim 6 or 7,
In the removing step, the inner peripheral surface of the coolant passage is polished. In the manufacturing method of the cylinder block according to claim 8,
In the removing step, using a polishing tool in which abrasive grains are attached to a cylindrical fibrous portion provided on the rotating shaft, the rotating shaft of the polishing tool is rotated and the inner diameter of the coolant passage is adjusted. Cylinder block characterized by inserting said fibrous portion having substantially the same outer diameter into said cooling fluid passage and removing the impregnating material formed on the inner peripheral surface of said cooling fluid passage by polishing Manufacturing method.

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