JP2012112332A - Cylinder block of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize a temperature distribution around a cylinder bore by forming an anodic oxide coating on a sidewall of a water jacket.SOLUTION: Since a water jacket 13 is formed on a cylinder block 11 so as to surround a cylinder bore 14 where a piston 15 slides, the cylinder block 11 having a temperature raised by an operation of an internal combustion engine is cooled by cooling water flowing through the water jacket 13, wherein an anodic oxide coating 21 superior in heat conductivity is formed on a sidewall 13a of the water jacket 13. Since the height H of the anodic oxide coating 21 in a high temperature part of the sidewall 13 is higher than the height H of the anodic oxide coating 31 in a low-temperature part, the calorific value released from the high temperature part to the cooling water is larger than that from the low-temperature part to the cooling water. Accordingly, a temperature of each part of the cylinder bore 14 is equalized to maintain circularity, and sliding resistance of the piston 15 relative to the cylinder bore 14 is reduced.

Description

  In the present invention, a cylinder bore in which a piston slides and a water jacket surrounding the cylinder bore are formed in the cylinder block, a cylinder head is provided on one end side in the cylinder axis direction of the cylinder block, and the cylinder axis direction of the cylinder block The present invention relates to a cylinder block of an internal combustion engine in which a crankcase is provided on the other end side.

  By forming an anodic oxide coating on the side wall of the water jacket of the cylinder head of the internal combustion engine, the heat transfer efficiency between the side wall of the cylinder head and the cooling water is increased, so that the cylinder head can be efficiently cooled by the water jacket. This is known from the following patent document 1.

JP 2009-209883 A

  By the way, the temperature distribution around the cylinder bore formed in the cylinder block of the internal combustion engine is not uniform, and is not uniform in the cylinder axial direction or the circumferential direction. There is a problem of increased friction. When the anodized film described in Patent Document 1 is applied to the side wall of the water jacket around the cylinder bore, cooling around the cylinder bore can be promoted, but the cylinder axial direction or circumferential direction is not uniform. Therefore, it is difficult to sufficiently reduce the friction between the cylinder bore and the piston.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to make the temperature distribution around the cylinder bore uniform by forming an anodized film on the side wall of the water jacket.

  In order to achieve the above object, according to the first aspect of the present invention, a cylinder bore in which a piston slides and a water jacket surrounding the cylinder bore are formed in the cylinder block, and a cylinder axial direction of the cylinder block is formed. In a cylinder block of an internal combustion engine in which a cylinder head is provided on one end side and a crankcase is provided on the other end side in the cylinder axial direction of the cylinder block, an anodized film is formed on the side wall of the water jacket, and the high temperature of the side wall A cylinder block of an internal combustion engine is proposed in which the amount of the anodized film in the part is larger than the amount of the anodized film in the low temperature part of the side wall.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the amount of the anodic oxide coating on the cylinder head side in the cylinder axial direction is determined by the amount of the anode on the crankcase side in the cylinder axial direction. A cylinder block of an internal combustion engine is proposed, characterized in that it is greater than the amount of oxide film.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, the cylinder block has one side of the cylinder row line on the intake side and the other side of the cylinder row line on the exhaust side, A cylinder block of an internal combustion engine is proposed in which the amount of the anodic oxide coating on the exhaust side of the block is greater than the amount of the anodic oxide coating on the intake side of the cylinder block.

  According to the invention described in claim 4, in addition to the structure of claim 1, the amount of the anodized film of the water jacket facing the opposing portions of the two cylinder bores may be in a portion other than the opposing portions. A cylinder block for an internal combustion engine is proposed in which the amount of the anodic oxide coating on the water jacket is larger.

  According to the invention described in claim 5, in addition to the configuration of claim 1, the water jacket includes a cooling water inlet and a cooling water outlet, and the anodized film on the cooling water outlet side of the water jacket. A cylinder block of an internal combustion engine is proposed in which the amount of is larger than the amount of the anodic oxide coating on the cooling water inlet side.

  According to the invention described in claim 6, in addition to the structure of any one of claims 1 to 5, an anodized film is also formed on the cylinder bore in addition to the side wall of the water jacket. A cylinder block for an internal combustion engine is proposed.

  According to the first aspect of the present invention, since the water jacket is formed in the cylinder block so as to surround the cylinder bore in which the piston slides, the cylinder block whose temperature has increased due to the operation of the internal combustion engine is cooled with the coolant flowing through the water jacket. To be cooled. At this time, an anodic oxide film having excellent heat conductivity is formed on the side wall of the water jacket, and the amount of the anodic oxide film in the high temperature part of the side wall is larger than the amount of the anodic oxide film in the low temperature part of the side wall. The amount of heat released from the water jacket to the water jacket water is made larger than the amount of heat released from the low temperature part to the water jacket water, so that the temperature of each part of the cylinder bore is made uniform and roundness is maintained, and the piston slides against the cylinder bore. Resistance can be reduced.

  According to the second aspect of the present invention, the cylinder block has a high temperature on the cylinder head side in the cylinder axial direction and a low temperature on the crankcase side in the cylinder axial direction. By making it larger than the amount of the anodic oxide coating, the temperature of each part of the cylinder bore can be made uniform and the sliding resistance of the piston can be reduced.

  According to the configuration of claim 3, the cylinder block has a low temperature on the intake side on one side of the cylinder row line and a high temperature on the exhaust side on the other side of the cylinder row line. By making it larger than the amount of the anodic oxide coating on the side, the temperature of each part of the cylinder bore can be made uniform and the sliding resistance of the piston can be reduced.

  Further, according to the configuration of claim 4, the temperature of the cylinder block is high at the facing part of the two cylinder bores and is low at the other part, but the amount of the anodic oxide coating on the water jacket facing the facing part is By making the amount larger than the amount of the anodic oxide coating on the water jacket facing other parts, the temperature of each part of the cylinder bore can be made uniform and the sliding resistance of the piston can be reduced.

  According to the fifth aspect of the present invention, the temperature of the cylinder block is low on the cooling water inlet side of the water jacket where the cooling water temperature is low and high on the cooling water outlet side of the water jacket where the cooling water temperature is high. By making the amount of the anodic oxide coating on the cooling water outlet side larger than the amount of the anodic oxide coating on the cooling water inlet side, the temperature of each part of the cylinder bore can be made uniform and the sliding resistance of the piston can be reduced.

  According to the sixth aspect of the present invention, since the anodic oxide film is formed on the cylinder bore in addition to the side wall of the water jacket, the surface roughness of the cylinder bore can be improved and the sliding resistance of the piston can be further reduced. In addition, the heat of the combustion chamber is hardly transmitted to the cylinder bore by the anodic oxide coating constituting the heat insulating layer, so that the temperature of the combustion chamber can be increased and the energy loss can be reduced. In addition, since the anodized film can be simultaneously formed on both the side wall of the water jacket and the cylinder bore, it is possible to reduce the number of steps for masking the portion where the anodized film is not formed.

The longitudinal cross-sectional view of an internal combustion engine. FIG. 2 is a two-direction arrow view of FIG. 1. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2. The figure which shows distribution of the height of the anodic oxide film along the flow direction of the cooling water of a water jacket. The graph which shows the change of the diameter of the cylinder bore along a cylinder axis.

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

  As shown in FIGS. 1 and 2, four cylinder sleeves 12 are embedded in the cylinder block 11 of the in-line four-cylinder internal combustion engine along the cylinder line L1, and the outer peripheral surfaces of the cylinder sleeves 12 are embedded. A water jacket 13 is formed so as to surround the frame. The cylinder block 11 of the present embodiment is a siamese type, and the water jacket 13 is not formed between adjacent cylinder sleeves 12... Thereby shortening the dimension of the internal combustion engine in the direction of the cylinder row L1. .

  A piston 15 slidably fitted into a cylinder bore 14 formed by the inner peripheral surface of each cylinder sleeve 12 is connected to a crankshaft 17 via a connecting rod 16. A cylinder head 18 is coupled to one end of the cylinder block 11 in the cylinder axis L2 direction, and a combustion chamber 19 is formed between the cylinder block 11 and the cylinder head 18. A crankcase 20 that supports the crankshaft 17 is integrally formed on the other end side of the cylinder block 11 in the direction of the cylinder axis L2.

  A cooling water inlet 11 a to which cooling water is supplied from a water pump is formed at the end of the cylinder block 11 on the timing train side. The cooling water flowing into the water jacket 13 from the cooling water inlet 11 a After flowing to the transmission side along the intake side surface, changing the direction by 180 ° and flowing along the exhaust side surface of the cylinder block 11, from the coolant outlet 18a facing the end of the cylinder block 11 on the timing train side. It flows into the water jacket of the cylinder head 18. A partition plate 23 is attached to the water jacket 13 so as to partition the cooling water inlet 11a and the cooling water outlet 18a.

  FIG. 3 shows a cross section of the cylinder block 11 cut along a cut surface passing through the cylinder axis L2. The side wall 13a on the inner side (cylinder bore 14 side) of the water jacket 13 is connected to the crankcase from the deck surface 11b side of the cylinder block 11. An anodized film 21 is formed to a predetermined height H toward the side 20. The anodic oxide coating 21 is in direct contact with the cooling water inside the water jacket 13. An anodized film 22 is also formed on the cylinder bore 14 of the cylinder sleeve 12. The anodic oxide coating 22 of the cylinder bore 14 is formed over the entire area of the cylinder bore 14, while the anodic oxide coating 21 on the side wall 13 a of the water jacket 13 is formed within a predetermined height H from the deck surface 11 b of the cylinder block 11. .

  The anodic oxide coatings 21 and 22 are made of oxide ceramics or nitride ceramics such as keronite, ceratronic, pyridinium chlorochromium oxide, and the anodizing treatment is performed by immersing the cylinder block 11 as a base material in an electrolytic cell. Is formed. The thickness of the anodic oxide coating 21 on the side wall 13a of the water jacket 13 and the anodic oxide coating 22 on the cylinder bore 14 is several μm to several tens of μm. In FIG.

  FIG. 4 shows the distribution of the height H of the anodic oxide coating 21 on the side wall 13a of the water jacket 13 in the cylinder axis L2 direction, and the solid line corresponds to the anodic oxide coating 21 of the water jacket 13 on the intake side of the cylinder block 11. The broken line corresponds to the anodic oxide coating 21 of the water jacket 13 on the exhaust side of the cylinder block 11.

  Taking the anodic oxide coating 21 on the intake side of the water jacket 13 indicated by a solid line as an example, the height H of the anodic oxide coating 21 in the cylinder axis L2 direction is the both ends of the water jacket 13 in the cylinder row line L1 direction (see FIG. 2). The minimum value H1 is in the vicinity of the portion a and g), and the maximum value H4 is between the center # 2 cylinder and # 3 cylinder (see portion d in FIG. 2), and the outer # 1 cylinder and # 2 cylinder 2 (see part b in FIG. 2) and between the outer # 4 cylinder and # 3 cylinder (see part f in FIG. 2), the maximum value H3 is reached, and an intermediate position between parts b and d (c in FIG. 2). Part) and an intermediate position between the parts f and d (see part e in FIG. 2), the minimum value H2.

  The reason why the height H of the anodic oxide coating 21 is not minimized in the a part and the g part is that the cooling water flow is stagnant in the vicinity of the partition plate 23 inserted in the water jacket 13 (see the a part), and the cooling efficiency is lowered. In addition, since the flow of the cooling water is peeled off at the folded portion (see part g) of the water jacket 13 from the intake side to the exhaust side, the cooling efficiency is lowered. Therefore, the height H of the anodized film 21 is reduced at those portions. This is because it increases locally.

  In the present embodiment, the thickness of the anodic oxide coating 21 is the same in each part.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the internal combustion engine is operated, heat generated by combustion of the air-fuel mixture in the combustion chamber 19 is transmitted from the cylinder bores 14 to the cylinder sleeve 12 and the cylinder block 11. The heat is formed in the water formed in the cylinder block 11. The cylinder sleeves 12 and the cylinder block 11 are cooled by being absorbed by the cooling water flowing through the jacket 13. Although the outer periphery of the cylinder bores 14 is surrounded by the water jacket 13, the temperature of the outer periphery of the cylinder bores 14 becomes uneven for the following reasons.

  That is, as shown in FIG. 2, the position A facing the two cylinder sleeves 12, 12 not only receives heat from both cylinder sleeves 12, 12, but also between the two cylinder sleeves 12, 12. Since the water jacket 13 does not exist and the water jacket 13 closest to the water jacket 13 is bent, the smooth flow of the cooling water is hindered and the heat dissipation is reduced, so that the temperature is increased. In particular, the position A in the center of the cylinder row L1 facing the # 2 cylinder and the # 3 cylinder transfers heat from the # 1 and # 2 cylinders and heat from the # 4 and # 3 cylinders. It becomes the highest temperature.

  On the other hand, the positions B at both ends in the direction of the cylinder line L1 are opposed to only one cylinder sleeve 12, and the cooling water flows smoothly through the water jacket 13, so that the temperature becomes the lowest. Further, at the position C farthest from the cylinder row line L1, the cooling water flows smoothly through the water jacket 13, but receives some heat from the cylinder sleeves 12 and 12 on both sides, so that the temperature becomes an intermediate temperature.

  For this reason, when the temperature of the cylinder bore 14 of each cylinder sleeve 12 becomes uneven in the circumferential direction, the roundness of the cylinder bore 14 is lost, and the sliding resistance of the piston 15 fitted therein increases. There's a problem.

  In order to avoid this, in the present embodiment, the amount of the anodic oxide coating 21 on the side wall 13a of the water jacket 13 facing the high temperature portion of the cylinder bore 14 is increased, that is, the anodic oxide coating 21 in the cylinder axis L2 direction. By increasing the height H, the cooling of the high temperature part is promoted, and the amount of the anodic oxide film 21 on the side wall 13a of the water jacket 13 facing the low temperature part of the cylinder bore 14 is reduced. By reducing the height H in the direction of the cylinder axis L2, the cooling of the low temperature part is suppressed, and thereby the temperature distribution in the circumferential direction of each cylinder bore 14 is made uniform.

  To explain this further, since the anodic oxide coating 21 is porous, the cooling water that has entered the micropores boiled by receiving a lot of heat from the surroundings (subcool boiling phenomenon), and heat is transferred from the anodic oxide coating 21. By taking away, the heat transfer property of the side wall 13a of the water jacket 13 is improved. As a result, the greater the amount of the anodic oxide coating 21, that is, the higher the height H of the anodic oxide coating 21 in the cylinder axis L2 direction, the more easily the heat of the cylinder bore 14 is taken away by the cooling water, thereby improving the cooling performance.

  As is apparent from FIG. 4, the amount of the anodic oxide coating 21 is increased at the positions b, d, and f of the water jacket 13 facing the A position where the temperature is high, and a and g of the water jacket 13 facing the B position where the temperature is low. The amount of the anodic oxide coating 21 is reduced at the position, and the amount of the anodic oxide coating 21 is made moderate at the positions c and e of the water jacket 13 facing the C position where the temperature becomes intermediate, so that the cooling corresponding to the temperature of the cylinder bore 14 is achieved. The temperature distribution in the circumferential direction of each cylinder bore 14 can be made uniform by exhibiting the characteristics, the roundness of the cylinder bore 14 can be secured, and the sliding resistance of the piston 15 can be reduced.

  Further, the cooling water flowing in from the cooling water inlet 11a of the water jacket is discharged from the cooling water outlets 18a, after the temperature gradually rises by exchanging heat with the cylinder block 11. Therefore, the temperature on the exhaust side near the cooling water outlet 18a of the cylinder block 11 becomes higher than the temperature on the intake side near the cooling water inlet 11a, so that the temperature distribution of the cylinder bore 14 becomes higher on the exhaust side and lower on the intake side. In the present embodiment, the height H on the exhaust side of the anodic oxide coating 21 of the water jacket 13 (see the broken line in FIG. 4) is higher than the height H on the intake side (see the solid line in FIG. 4). The exhaust side cooling performance can be made higher than the cooling performance on the intake side where the temperature is low, and the temperatures on the intake side and the exhaust side of the cylinder bore 14 can be made uniform.

  In addition, if the height H of the anodic oxide coating 21 of the water jacket 13 is gradually increased from the cooling water inlet 11a toward the cooling water outlet 18a, the cooling effect by the anodic oxide coating 21 is reduced according to the decrease in the cooling water temperature. The temperature of each part of the cylinder bore 14 can be made more uniform.

  Considering the temperature distribution in the cylinder axis L2 direction of each cylinder bore 14, the end on the cylinder head 18 side of the cylinder bore 14 close to the combustion chamber 19 becomes high temperature, and the end on the crankcase 20 side far from the combustion chamber 19 is low temperature. become. Correspondingly, an anodic oxide coating 21 is formed in the entire region in the circumferential direction at the end of the cylinder bore 14 on the side of the cylinder head 18 at a high temperature, and at the end of the cylinder bore 14 at the side of the crankcase 20 at a low temperature. Since the anodic oxide coating 21 is formed only in a part of the circumferential direction (see FIG. 4), the temperature distribution of the cylinder bore 14 can be made uniform in the cylinder axis L2 direction.

  The graph of FIG. 5 shows the amount of deformation (diameter change) in the intake / exhaust direction of the cylinder bore 14 during operation of the internal combustion engine in accordance with the depth from the deck surface 11b of the cylinder block 11 (that is, the height H). It is shown. In contrast to the conventional example indicated by the broken line (without the anodic oxide coating 21), in the present embodiment indicated by the solid line, it can be seen that the diameter of the cylinder bore 14 is uniform in the direction of the cylinder axis L2.

  Further, since the surface roughness of the base material is improved when the anodic oxide coating is formed, the surface roughness of the cylinder bore 14 is improved by the anodic oxide coating 22 formed on the cylinder bore 14, and the sliding of the piston 15 sliding on the cylinder bore 14 is performed. The resistance can be further reduced.

  Further, when the anodic oxide coating 21 is formed on the side wall 13a of the water jacket 13 through which the cooling water flows, the heat transfer performance is improved by the above-described subcool boiling phenomenon, but the cooling water does not contact the anodic oxide coating 22 formed on the cylinder bore 14. Therefore, the subcool boiling phenomenon does not occur, and conversely, the heat insulating property of the cylinder bore 14 is improved by the anodic oxide coating 22. As a result, the heat generated in the combustion chamber 19 becomes difficult to be transmitted to the Linder bore 14 side, so that the temperature of the combustion chamber 19 can be increased and energy loss can be reduced.

  Further, when the anodic oxide coating 21 is formed on the side wall 13a of the water jacket 13, the anodic oxide coating 22 can be formed on the cylinder bore 14 at the same time, thereby reducing the number of steps for masking the portion where the anodic oxide coating is not formed. Work efficiency can be increased.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the amount of the anodic oxide film 21 on the side wall 13a of the water jacket 13 is changed by the height H of the anodic oxide film 21, but this is changed by the thickness of the anodic oxide film 21. Also good. That is, the amount may be increased by increasing the thickness of the anodic oxide coating 21, and may be decreased by reducing the thickness of the anodic oxide coating 21. Furthermore, the region where the anodic oxide coating 21 is formed and the region where the anodic oxide coating 21 is not formed may be alternately arranged, and the amount of the anodic oxide coating 21 may be changed depending on the ratio of the areas of both regions.

  In the embodiment, the anodic oxide film 21 is formed only on the side wall 13a on the inner side (on the cylinder bore 14 side) of the water jacket 13, but the anodic oxide film 21 can be formed on the outer side wall.

  Although the cylinder block 11 of the embodiment is a siamese type, the present invention can also be applied to a cylinder block 11 that is not a siamese type.

  In the embodiments, a multi-cylinder internal combustion engine is illustrated, but the present invention can also be applied to a single-cylinder internal combustion engine.

11 Cylinder block 11a Cooling water inlet 13 Water jacket 13a Side wall 14 Cylinder bore 15 Piston 18 Cylinder head 18a Cooling water outlet 20 Crankcase 21 Anodized film 22 Anodized film L1 Cylinder row line L2 Cylinder axis

Claims (6)

A cylinder bore (14) in which the piston (15) slides and a water jacket (13) surrounding the cylinder bore (14) are formed in the cylinder block (11), and the cylinder axis (L2) of the cylinder block (11) In a cylinder block of an internal combustion engine in which a cylinder head (18) is provided on one end side in the direction and a crankcase (20) is provided on the other end side in the cylinder axis (L2) direction of the cylinder block (11).
An anodized film (21) is formed on the side wall (13a) of the water jacket (13), and the amount of the anodized film (21) in the high temperature part of the side wall (13a) is the low temperature part of the side wall (13a). The cylinder block of the internal combustion engine, wherein the amount is larger than the amount of the anodic oxide coating (21).   The amount of the anodized film (21) on the cylinder head (18) side in the cylinder axis (L2) direction is the amount of the anodized film (21) on the crankcase (20) side in the cylinder axis (L2) direction. The cylinder block of the internal combustion engine according to claim 1, wherein the cylinder block is more than.   In the cylinder block (11), one side of the cylinder row (L1) is an intake side and the other side of the cylinder row (L1) is an exhaust side, and the anodized film on the exhaust side of the cylinder block (11) 2. The cylinder block of the internal combustion engine according to claim 1, wherein the amount of (21) is greater than the amount of the anodic oxide coating (21) on the intake side of the cylinder block (11).   The amount of the anodic oxide coating (21) of the water jacket (13) facing the opposing portions of the two cylinder bores (14) is the same as the anodic oxide coating (21) of the water jacket (13) facing the portion other than the opposing portions. 21. The cylinder block of the internal combustion engine according to claim 1, wherein the cylinder block is larger than 21).   The water jacket (13) includes a cooling water inlet (11a) and a cooling water outlet (18a), and the amount of the anodic oxide coating (21) on the cooling water outlet (18a) side of the water jacket (13) is The cylinder block of the internal combustion engine according to claim 1, characterized in that it is larger than the amount of the anodic oxide coating (21) on the cooling water inlet (11a) side.   The anodic oxide film (22) is formed on the cylinder bore (14) in addition to the side wall (13a) of the water jacket (13), according to any one of claims 1 to 5. A cylinder block of the internal combustion engine described.

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