JP4784634B2 - cylinder head - Google Patents

Description

  The present invention relates to a cylinder head.

  The exhaust ports of adjacent cylinders are gathered at the exhaust collecting part in the cylinder head, and a partition wall for separating the exhaust ports of these adjacent cylinders extends from between these adjacent cylinders to the exhaust collecting part. A cylinder head in which a head bolt insertion hole is formed in the wall and an oil passage is formed in the partition wall between the front end of the partition wall facing the exhaust collecting portion and the head bolt insertion hole is known ( (See Patent Document 1). In an internal combustion engine equipped with this cylinder head, the temperature of the exhaust collecting portion where the exhaust gas discharged from each cylinder gathers is particularly high, so the temperature near the tip of the partition wall facing this exhaust collecting portion is the highest. . Therefore, in this internal combustion engine, the temperature of the inner peripheral surface of the oil passage formed in the partition wall is increased, so that the oil flowing in the oil passage is quickly heated at a low temperature.

On the other hand, in an internal combustion engine equipped with this cylinder head, there is a risk of oil overheating. Therefore, a cylinder head in which a cooling water passage is formed in the partition wall adjacent to the oil passage is known (see Patent Document 2). In the internal combustion engine having this cylinder head, the oil passage is cooled by the cooling water flowing in the cooling water passage, so that the oil is prevented from overheating.
Japanese Patent No. 3605521 JP 2002-70641 A

  As described above, when the cylinder head described in Patent Document 1 is used, the oil flowing in the oil passage is overheated, and there is a problem that the oil is seized on the inner peripheral surface of the oil passage. In addition, when the cylinder head described in Patent Document 2 is used, the temperature of the inner peripheral surface of the oil passage located on the cooling water passage side decreases, but the inside of the oil passage located on the opposite side of the cooling water passage is reduced. Since no means for suppressing heat transfer is provided between the peripheral surface and the front end of the partition wall, the inner peripheral surface of the oil passage located on the opposite side of the cooling water passage is overheated, so that the oil is There arises a problem that seizure occurs on the inner peripheral surface of the passage.

  Further, in the cylinder heads described in Patent Documents 1 and 2, since no particular attention is paid to suppressing heat transfer to the head bolt insertion hole boss formed in the partition wall, the cylinder head is formed in the partition wall. The temperature of the head bolt insertion hole boss is considerably higher than that of other head bolt insertion hole bosses. As a result, the head bolt insertion hole boss formed in the partition wall expands greatly compared to other head bolt insertion hole bosses, so that the head bolt insertion hole boss formed in the partition wall is greatly compressed. There is a problem that stress is generated and thus the durability of the head bolt insertion hole boss formed in the partition wall is lowered.

  In order to solve the above problem, according to the present invention, the exhaust ports of adjacent cylinders are gathered at the exhaust collecting portion in the cylinder head, and the partition walls for partitioning the exhaust ports of these adjacent cylinders are adjacent to each other. The head bolt insertion hole is formed in this partition wall from between the cylinders to be exhausted, and the oil in the partition wall between the front end of the partition wall facing the exhaust collection part and the head bolt insertion hole In the cylinder head in which the passage is formed, a heat insulating layer is formed in the partition wall between the tip of the partition wall and the oil passage, and an oil passage is formed in the central portion of the heat insulating layer. The head bolt insertion hole boss portion on the tip end side extends in an arc around the axis of the head bolt insertion hole along substantially the outer periphery of the boss.

  Since a heat insulating layer is formed between the front end of the partition wall and the oil passage, heat transfer from the front end of the partition wall to the oil passage is blocked or suppressed by the heat insulating layer, so that the oil in the oil passage is It is possible to prevent seizure on the inner peripheral surface of the oil passage. Also, when viewed from the cylinder head side, the oil passage forms a heat transfer absorption layer. Accordingly, in the present invention, the heat insulating layer and the heat transfer absorption layer are arranged in series between the partition wall tip and the head bolt insertion hole, so that heat is transferred from the partition wall tip to the head bolt insertion hole. Thus, the durability of the head bolt insertion hole boss can be improved.

  FIG. 1 shows a plan sectional view of a cylinder head 1 that is integrally cast from, for example, an aluminum alloy. 1 indicate the positions of the first cylinder # 1, the second cylinder # 2, the third cylinder # 3, and the fourth cylinder # 4. Accordingly, the cylinders shown in FIG. It can be seen that the internal combustion engine provided with the head 1 is an in-line four-cylinder internal combustion engine. In FIG. 1, 2 indicates a valve port opened and closed by an intake valve, and 3 indicates a valve port opened and closed by an exhaust valve. Therefore, it can be seen that each cylinder # 1, # 2, # 3, # 4 has a pair of intake valves and a pair of exhaust valves.

  The cylinder head 1 is actually formed with a cooling water passage extending along a complicated path, a support portion for a valve mechanism, an insertion portion for a spark plug, an insertion portion for a fuel injection valve, etc. These are omitted.

  In the cylinder head 1, an intake port 4 for each cylinder # 1, # 2, # 3, and # 4 and an exhaust port 5 for each cylinder # 1, # 2, # 3, and # 4 are formed. As can be seen from FIG. 1, each intake port 4 and each exhaust port 5 are arranged symmetrically with respect to a symmetry plane KK passing through the center of the longitudinal axis of the cylinder head 1 and perpendicular to the longitudinal axis of the cylinder head 1. Further, all the exhaust ports 5 are gathered in the exhaust collecting portion 6.

  As shown in FIG. 1, a partition wall 7 for partitioning the exhaust ports 5 of the adjacent cylinders # 1 and # 2 extends from the adjacent first cylinder # 1 and the second cylinder # 2 to the exhaust collecting portion 6. A partition wall 8 for partitioning the exhaust ports 5 of the adjacent cylinders # 2 and # 3 extends from the adjacent second cylinder # 2 and the third cylinder # 3 to the exhaust collecting portion 6 and adjacent to each other. A partition wall 9 for partitioning the exhaust ports 5 of the adjacent cylinders # 3 and # 4 extends from the third cylinder # 3 and the fourth cylinder # 4 to the exhaust collecting portion 6.

  On the intake port 4 side, five head bolt insertion holes 10 are formed on the cylinder head 1 in a straight line so as to be positioned on both sides of each intake port 4, and on the exhaust port 5 side, five The head bolt insertion holes 11 a, 11 b, 11 c, 11 d, 11 e are formed in the cylinder head 1 so as to be aligned in a straight line so as to be located on both sides of each exhaust port 5. Of the five head bolt insertion holes on the exhaust port 5 side, three head bolt insertion holes 11b, 11c, and 11d are formed in the corresponding partition walls 7, 8, and 9, respectively. The holes 11a and 11e are formed outside the intake port group.

  An oil passage 12 is formed in the vicinity of the head bolt insertion holes 11a and 11e formed outside the intake port group, and the oil passage 13 is also formed in the vicinity of the head bolt insertion hole 11c formed in the partition wall 8. Is formed. The oil passages 12 and 13 are formed in the vicinity of the head bolt insertion holes 11a, 11c and 11e in this way, respectively, because the cylinder head 1 is moved by the head bolts inserted into the head bolt insertion holes 10 and 11a to 11e. This is because oil in the oil passages 12 and 13 is prevented from leaking from between the cylinder head 1 and the cylinder block when fastened on the cylinder block. That is, there is no gap between the pressure contact surfaces of the cylinder head 1 and the cylinder block around the head bolt, so that if these oil passages are formed in the cylinder head 1 and the cylinder block in the vicinity of the head bolt, the oil passages are aligned. This is because oil does not leak from the connecting portion of the passage.

  As described above, when the temperature of the oil passage rises, the oil is baked on the inner peripheral surface of the oil passage. Further, when the temperature around the head bolt insertion hole rises, a large compressive stress is generated around the head bolt insertion hole, so that the durability around the head bolt insertion hole is lowered. By the way, exhaust gas is sequentially discharged from each cylinder # 1, # 2, # 3, # 4 during one cycle, and the temperature increases as the number of times of contact with the exhaust gas sequentially discharged from each cylinder increases. Become.

  From this point of view, the partition wall 7 comes into contact with the exhaust gas exhausted from the first cylinder # 1 and the exhaust gas exhausted from the second cylinder # 2, so that the partition wall 7 is twice in one cycle. Contact with exhaust gas. Similarly, the partition wall 9 contacts the exhaust gas twice during one cycle. On the other hand, the front end of the partition wall 8 comes into contact with the exhaust gas discharged from all the cylinders # 1, # 2, # 3, and # 4, so that it comes into contact with the exhaust gas four times during one cycle. Therefore, the temperature at the tip of the partition wall 8 is the highest in the cylinder head 1.

  Accordingly, the oil in the oil passage 13 formed in the partition wall 8 is most easily seized on the inner peripheral surface of the oil passage 13 in the oil passage, and is formed in the partition wall 8 in the head bolt insertion hole. The strength around the head bolt insertion hole 11c is most likely to deteriorate. Therefore, in the present invention, in particular, the temperature around the oil passage 13 and the head bolt insertion hole 11c formed in the partition wall 8 is suppressed from increasing.

  2 shows an enlarged view around the partition wall 8 of FIG. 1, and FIG. 3 shows a cross-sectional view taken along line III-III of FIG. 2 and 3, the cylinder head 1 is placed on the cylinder block 14, and the cylinder head 1 is fastened on the cylinder block 14 by the head bolt 15 inserted into the head bolt insertion hole 11c. ing. A head bolt similar to the head bolt 15 shown in FIG. 3 is also inserted into the other head bolt insertion holes 10, 11a, 11b, 11d, and 11e.

  As shown in FIGS. 2 and 3, according to the present invention, the heat insulating layer 16 is formed between the front end 8 a of the partition wall 8 facing the exhaust collecting portion 6 and the oil passage 13. More specifically, a boss portion of the head bolt insertion hole 11c is formed around the head bolt insertion hole 11c, and the boss portion 17 on the partition wall front end portion 8a side is substantially half a circumference around the axis of the head bolt insertion hole 11c. It has a hollow cylindrical shape extending over the entire area.

  As shown in FIG. 2, a thin partition wall 19 is formed around the boss portion 17 so as to extend in an arc around the axis of the head bolt insertion hole 11c with a certain distance from the semi-cylindrical outer peripheral surface 18 of the boss portion 17. In the embodiment shown in FIGS. 2 and 3, the thin partition wall 19 is formed integrally with the cylinder head 1. The oil passage 13 is formed between the semicylindrical outer peripheral surface 18 of the boss portion 17 and the thin partition wall 19, and the oil passage 13 extends along the semicylindrical outer peripheral surface 18 of the boss portion 17 with the head bolt insertion hole 11 c. Is extending in an arc around the entire axis.

  On the other hand, the heat insulating layer 16 extends around the axis of the head bolt insertion hole 11c along the outer peripheral edge of the oil passage 13 on the partition wall front end 8a side. Specifically, the heat insulating layer 16 extends along the outer peripheral surface of the thin partition wall 19 around the axis of the head bolt insertion hole 11c.

  As shown in FIG. 3, the upper end portion of the thin partition wall 19 protrudes upward from the upper wall surface of the cylinder head 1 so that the oil guided onto the cylinder head 1 can be captured in the oil passage 13. The lower end of 13 communicates with an oil passage 20 formed in the cylinder block 14. On the other hand, in the embodiment shown in FIG. 2 and FIG. 3, the heat insulating layer 16 includes a blow-by gas passage, and the blow-by gas passage 16 communicates with the blow-by gas passage 21 of the cylinder block 14.

  As shown in FIGS. 1 to 3, according to the present invention, a heat insulating layer 16 that completely covers the partition wall tip 8 a side of the oil passage 13 is formed between the tip 8 a of the partition wall 8 and the oil passage 13. Therefore, the heat transfer from the partition wall tip 8a toward the oil passage 13 is blocked or suppressed by the heat insulating layer 16, so that the oil in the oil passage 13 is baked on the inner peripheral surface of the oil passage 13. Can be prevented.

  Further, when viewed from the cylinder head 1 side, the oil passage 13 forms a heat transfer absorption layer. Accordingly, in the present invention, since the heat insulating layer 16 and the heat transfer layer 13 are arranged in series between the partition wall tip 8a and the head bolt insertion hole 11c, the partition wall tip 8a and around the head bolt insertion hole 11c are formed. Heat transfer to the is suppressed. In addition, since the heat insulating layer 16 and the heat transfer layer 13 extend so as to completely cover the exhaust assembly 6 side of the boss portion 17, heat transfer from the partition wall tip 8a to the periphery of the head bolt insertion hole 11c is large. Therefore, the durability of the boss portion 17 of the head bolt insertion hole 11c can be improved.

  4 and 5 show another embodiment. In this embodiment, a heat insulating layer 22 extending in an arc shape is formed along the semicylindrical outer peripheral surface of the boss portion 17 around the semicircular circumference around the axis of the head bolt insertion hole 11c. An oil passage 23 is formed in the bottom. Therefore, also in this embodiment, the heat insulating layer 22 is formed between the tip 8a of the partition wall 8 and the oil passage 23.

  As can be seen from FIGS. 4 and 5, the heat insulating layer 22 is filled with a heat insulating material, and the oil passage 23 is formed in the heat insulating material. Further, upstanding ribs 24 extending along the outer peripheral edge of the heat insulating layer 22 are formed on the cylinder head 1 in order to capture oil.

  Also in this embodiment, since the heat insulating layer 22 is formed between the tip 8a of the partition wall 8 and the oil passage 23, the heat transfer from the partition wall tip 8a toward the oil passage 23 is blocked or prevented by the heat insulating layer 22. Thus, it is possible to prevent the oil in the oil passage 23 from being seized on the inner peripheral surface of the oil passage 23. Also in this embodiment, since the heat insulating layer 22 and the transfer heat absorption layer 23 are arranged in series between the partition wall tip 8a and the head bolt insertion hole 11c, the head bolt insertion hole 11c extends from the partition wall tip 8a. The transfer of heat to the surroundings is suppressed, and thus the durability of the boss portion 17 can be improved.

  6 and 7 show still another embodiment. Also in this embodiment, a heat insulating layer 25 extending in an arc shape is formed along the semicylindrical outer peripheral surface 18 of the boss portion 17 around the axis of the head bolt insertion hole 11c, and the center of the heat insulating layer 25 is formed. An oil passage 26 is formed in the part. Therefore, also in this embodiment, the heat insulating layer 25 is formed between the front end 8a of the partition wall 8 and the oil passage 26.

  As shown in FIGS. 6 and 7, in this embodiment, the oil passage 26 is formed in a pipe 27 extending through the central portion of the heat insulating layer 25, and the heat insulating layer 25 around the pipe 27 is made up of a space. Also in this embodiment, since the heat insulating layer 25 is formed between the tip 8a of the partition wall 8 and the oil passage 26, the heat transfer from the partition wall tip 8a toward the oil passage 26 is blocked or blocked by the heat insulating layer 25. Thus, the oil in the oil passage 26 can be prevented from being seized on the inner peripheral surface of the oil passage 26. Also in this embodiment, since the heat insulating layer 25 and the heat transfer heat absorbing layer 26 are arranged in series between the partition wall tip 8a and the head bolt insertion hole 11c, the partition wall tip 8a extends from the head bolt insertion hole. The transmission of heat around 11c is suppressed, and thus the durability of the boss portion 17 can be improved.

It is a plane sectional view of a cylinder head. It is an enlarged view around the partition wall 8 of FIG. It is sectional drawing seen along the III-III line of FIG. It is a plane sectional view of another example of cylinder head 1 showing the partition wall 8 circumference. It is sectional drawing seen along the VV line of FIG. FIG. 10 is a plan sectional view of still another embodiment of the cylinder head 1 showing the periphery of the partition wall 8. It is sectional drawing seen along the VII-VII line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 4 Intake port 5 Exhaust port 6 Exhaust collection part 7, 8, 9 Partition wall 10,11a, 11b, 11c, 11d, 11e Head bolt insertion hole 12,13,23,26 Oil passage 16,22,25 Thermal insulation layer

Claims (3)

  The exhaust ports of adjacent cylinders are gathered at an exhaust collecting portion in the cylinder head, and a partition wall for partitioning the exhaust ports of the adjacent cylinders extends from between the adjacent cylinders to the exhaust collecting portion, A cylinder head in which a head bolt insertion hole is formed in the partition wall, and an oil passage is formed in the partition wall between the front end portion of the partition wall facing the exhaust collecting portion and the head bolt insertion hole. A heat insulating layer is formed in the partition wall between the front end portion of the partition wall and the oil passage, and the oil passage is formed in a central portion of the heat insulating layer, and the heat insulating layer is on the front end portion side of the partition wall. A cylinder head extending in an arc around the axis of the head bolt insertion hole along substantially the outer circumference of the boss of the head bolt insertion hole.   The cylinder head according to claim 1, wherein the heat insulating layer is filled with a heat insulating material, and the oil passage is formed in the heat insulating material.   The cylinder head according to claim 1, wherein the oil passage is formed in a pipe extending through a central portion of the heat insulating layer, and the heat insulating layer around the pipe is a space.

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