JP2017190731A - Cylinder head for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize cooling performance of an entire manifold.SOLUTION: A cylinder head incorporating a manifold of an exhaust system of an engine includes cooling passages 4A, 4B, and 4C in which cooling water flows. The two cooling passages 4A and 4B of them are arranged to vertically fasten the manifold, and the remaining cooling passage 4C is a branch cooling passage which branches off from one of the cooling passages 4A and 4B and joins with the original cooling passages 4A and 4B after flowing around an outlet of a manifold collection portion.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a cylinder head incorporating a manifold of an engine exhaust system.

  2. Description of the Related Art Conventionally, a cylinder head and an exhaust manifold are integrally formed so that a plurality of exhaust ports connected to a combustion chamber of an engine merge in the cylinder head. In such a cylinder head, since the distance between the exhaust purification catalyst interposed in the exhaust system and the engine is shortened, the exhaust purification performance can be improved and the length of the exhaust system itself is shortened. There are advantages that the pressure loss of the exhaust gas is reduced and the engine space can be saved easily. On the other hand, in such a cylinder head, there is a problem that it is likely to become high temperature due to exhaust heat as compared with a cylinder head separately provided. Thus, it has been proposed to improve the cooling performance by circulating engine cooling water around the exhaust port or near the outlet of the manifold (see Patent Document 1).

JP 2008-309158 A

  By the way, the vicinity of the outlet of the manifold built in the cylinder head is a portion where the exhaust that has circulated through the exhaust ports gathers, and therefore, it tends to be particularly hot. On the other hand, if a flow path through which cooling water flows is provided in the vicinity of the outlet, the cooling performance of this portion can be ensured. However, since the temperature change in the vicinity of the outlet is large, simply providing a cooling passage may affect the cooling performance of other parts of the manifold.

  The present invention has been devised in view of such a problem, and an object thereof is to provide an engine cylinder head that can stabilize the cooling performance of the entire manifold. The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and has another function and effect that cannot be obtained by conventional techniques. is there.

  (1) An engine cylinder head disclosed herein is a cylinder head having a built-in manifold of an engine exhaust system, in which two coolants are arranged so that cooling water flows through the manifold and sandwiches the manifold from above and below. A branch, a cooling passage through which the cooling water circulates, branches from one of the two cooling passages, and merges with the one cooling passage through the periphery of the outlet portion of the manifold. Is provided.

(2) It is preferable that said one cooling channel | path has a guide part which guides the said cooling water to the said branch cooling channel | path.
(3) It is preferable that the cooling water in the one cooling passage flows from one of the front side and the rear side of the engine to the other (from one side to the other side). In this case, the guide portion is disposed downstream of the inlet portion of the branch cooling passage in the flow direction of the cooling water, and protrudes inward from the outer wall portion of the cylinder head forming the one cooling passage. It is preferable that the protrusion is provided.

(4) It is preferable to provide a screw hole drilled in the fastening surface between the cylinder head and the exhaust pipe. In this case, it is preferable that one screw hole is arranged above the opening at the downstream end of the manifold, and two screw holes are arranged below the opening.
(5) The branch cooling passage branches off from a lower cooling passage disposed along the lower surface of the manifold, and joins the lower cooling passage through the opening side of the upper screw hole. Is preferred.
(6) Alternatively, it is preferable that the branch cooling passages merge after branching from an upper cooling passage disposed along the upper surface of the manifold.

  Since the branch cooling passage that passes around the manifold outlet portion of the manifold returns to the branched cooling passage, changes in the cooling water temperature in the two cooling passages can be suppressed. Thereby, the cooling property of the whole manifold can be stabilized.

1 is a perspective view illustrating a cylinder head and a cylinder block of an engine according to an embodiment. It is a typical longitudinal section of an engine. It is a horizontal sectional view showing the shape of the exhaust port in the cylinder head. It is a perspective view which shows the cooling passage by the side of the exhaust in a cylinder head. (A) is a horizontal sectional view showing the upper part (upper cooling passage) of the cooling passage in FIG. 4, and (B) is a horizontal sectional view showing the lower part (lower cooling passage) of the cooling passage in FIG. (A) is the figure which looked at the fastening surface of the cylinder head from the front, (B) is a schematic diagram for demonstrating the structure of the cooling channel | path of FIG. 6 (A). It is a schematic diagram for demonstrating the structure of the cooling channel | path provided in the cylinder head which concerns on a modification.

  A cylinder head of an engine as an embodiment will be described with reference to the drawings. Each embodiment shown below is only an example, and there is no intention of excluding various modifications and application of technology that are not clearly shown in each of the following embodiments. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit thereof. Further, they can be selected as necessary, or can be appropriately combined.

[1. overall structure]
The cylinder head 1 of this embodiment is an exhaust manifold integrated cylinder head incorporating an exhaust system manifold (multi-branch pipe), and is attached to a cylinder block 2 of a water-cooled multi-cylinder engine 10. In the following description, the side on which the cylinder block 2 is fixed with respect to the cylinder head 1 is defined as the lower side, and the opposite side is defined as the upper side. A plurality of cylinders 3 are arranged in a row inside the engine 10. The example shown in FIG. 1 is an engine 10 of three cylinders (# 1, # 2, # 3 in order from the front side) in which three cylinders 3 are arranged in series. Hereinafter, the arrangement direction of the cylinders 3 is represented by a symbol L.

  As shown in FIGS. 1 and 2, a cooling passage 30 (water jacket) dug into a curved surface along the cylindrical surface 3 </ b> B is formed around the cylinder 3. The upper side of the cooling passage 30 is opened at the upper surface of the cylinder block 2 and communicates with an exhaust side cooling passage 4 (4B) and an intake side cooling passage 5 formed inside the cylinder head 1, respectively. Thereby, the outer peripheral portion of the exhaust port 6 is also cooled by engine cooling water (hereinafter referred to as “cooling water”). Here, for convenience, the cooling passages 4 and 5 on the cylinder head 1 side are divided into an exhaust side and an intake side and are provided with reference numerals, but these cooling passages 4 and 5 are integrated into the inside of the cylinder head 1. Provided.

  As shown in FIG. 2, a recess is formed on the lower surface of the cylinder head 1 as a ceiling surface 3A (ceiling surface of the combustion chamber), and an exhaust port 6 is connected to each combustion chamber. The exhaust port 6 is a multi-branch type exhaust passage that functions as an exhaust system manifold. As shown in FIG. 3, the upstream end of the exhaust port 6 has a shape branched into six and is connected to each exhaust valve hole 12. On the other hand, the downstream side of the exhaust port 6 has a shape in which individual passages are integrated into one inside the cylinder head 1. Hereinafter, the aggregated portion of the exhaust ports 6 is referred to as an exhaust collecting portion 6A.

  Here, of the imaginary lines extending horizontally through the center of the # 2 cylinder, a straight line perpendicular to the cylinder row direction L is defined as “center line C of engine 10”. On the other hand, it is disposed at a position offset to the rear side of the engine 10. Similarly, a single opening (hereinafter referred to as “exhaust port 7”) that becomes the downstream end of the exhaust collecting portion 6A is also provided at a position offset from the center line C to the rear side. 1 to 3, the side wall 8 on the exhaust side is provided with an overhanging portion 14 that bulges out in a half-moon shape toward the outside of the cylinder head 1 so as to surround the entire exhaust port 6. It is done.

  As shown in FIG. 6 (A), a flange portion 15 having a flat fastening surface 15A perpendicular to the flow direction of the exhaust is formed around the exhaust port 7. The flange portion 15 is a portion to which a downstream exhaust pipe (not shown) (including a pipe for connection with a catalyst device, a turbocharger, etc.) is fastened and fixed. The fastening surface 15A of the flange portion 15 is provided around the exhaust port 7 so as to surround the upper, lower, left, and right sides of the exhaust port 7 in an annular shape.

  The flange portion 15 is provided with a plurality of boss portions 19 for attaching fasteners such as bolts and screws. Each boss portion 19 is formed with a screw hole 20 having a groove on the inner cylinder surface to be screwed with the fastener. The drilling direction of the screw hole 20 is a direction perpendicular to the fastening surface 15A. The position of the boss portion 19 is set at a predetermined interval in the circumferential direction of the exhaust port 7. In the example shown in FIG. 6A, one boss portion 19 is formed on the upper side and two boss portions 19 on the lower side of the annularly arranged fastening surface 15A.

  The upper boss portion 19 (screw hole 20) is disposed above the exhaust port 7 (substantially above the center point P of the exhaust port 7 when the fastening surface 15A is viewed from the front). On the other hand, the lower two boss portions 19 (screw holes 20) are arranged on the left and right sides of the exhaust port 7 below the exhaust port 7 (substantially equidistant from the center point P of the exhaust port 7). Of these boss portions 19, the boss portions 19 located on the upper side are formed such that the upper ends of the boss portions 19 bulge slightly upward from the upper surface 14 </ b> A of the overhang portion 14. On the other hand, the lower boss part 19 is such that the lower end of each boss part 19 substantially coincides with the lower surface 14B of the overhanging part 14 (so as not to protrude downward from the lower surface 14B of the overhanging part 14). It is formed.

[2. Cooling passage]
The shape of the cooling passage 4 (water jacket) on the exhaust side inside the cylinder head 1 is illustrated in FIG. In the cylinder head 1, the exhaust port 6 is sandwiched from above and below as a cooling passage 4 through which cooling water for cooling around the exhaust port 6 (exhaust system manifold built in the cylinder head 1) flows. Two arranged cooling passages 4A and 4B are provided. Further, the cylinder head 1 is provided with a branch cooling passage 4 </ b> C for cooling the collecting portion outlet portion 6 </ b> B of the exhaust port 6.

  In the cylinder head 1 of the present embodiment, a cooling water inlet 44 through which cooling water is supplied from the water pump side is provided on the front side of the engine 10, and a cooling water outlet 45 is provided on the rear side. Accordingly, cooling water flows through the cooling passages 4A and 4B from the front side toward the rear side. The upper cooling passage 4A and the lower cooling passage 4B of the exhaust port 6 are disposed along the upper surface and the lower surface of the exhaust port 6, respectively. These cooling passages 4A and 4B are provided in communication with each other in the vicinity of the ceiling surface 3A of the cylinder 3, are independent from each other in the overhanging portion 14, and are substantially independent of the upper surface 14A and the lower surface 14B of the overhanging portion 14, respectively. It is provided in a planar shape that is parallel.

  5A and 5B show cross-sectional views in which the upper and lower cooling passages 4A and 4B are cut along a plane substantially parallel to the upper surface 14A and the lower surface 14B of the overhanging portion 14, respectively. 5A and 5B correspond to the outline of the ceiling surface 3A of the cylinder 3. Each of the cooling passages 4A and 4B in the overhanging portion 14 has such a shape that the cooling water meanders while flowing or merging and flows to the rear side. Further, as shown in FIG. 6A, the upper cooling passage 4A of the present embodiment is disposed below the screw hole 20 so as not to interfere with the upper screw hole 20 provided in the fastening surface 15A. The On the other hand, the lower cooling passage 4B is provided at a position where it interferes with the lower screw hole 20 when viewed from the front of the fastening surface 15A.

  The branch cooling passage 4C branches from one of the upper and lower cooling passages 4A and 4B, and passes through the periphery of the collecting portion outlet portion 6B of the exhaust port 6 to join the original cooling passages 4A and 4B. It is a part, and the collection part exit part 6B of the exhaust port 6 is cooled by circulating the cooling water inside. As shown in FIG. 3, the collecting portion outlet portion 6 </ b> B here means a portion closer to the downstream side of the exhaust collecting portion 6 </ b> A and a portion immediately upstream of the exhaust port 7.

  As shown in FIGS. 6A and 6B, the branch cooling passage 4C of the present embodiment branches from the lower cooling passage 4B, passes through the periphery of the collecting portion outlet portion 6B of the exhaust port 6, and again returns to the lower side. It merges with the cooling passage 4B. That is, a part of the cooling water flowing through the lower cooling passage 4B flows into the branch cooling passage 4C, cools the collecting portion outlet portion 6B of the exhaust port 6, and then again cools the cooling water in the lower cooling passage 4B. To join. Specifically, the branch cooling passage 4C is branched from the exhaust port 7 side with respect to the front boss portion 19 in the lower cooling passage 4B, and the front side, the upper side, and the rear side of the collective portion outlet portion 6B of the exhaust port 6 After passing through in this order, they merge on the exhaust port 7 side with respect to the rear boss portion 19 in the lower cooling passage 4B. The branch cooling passage 4 </ b> C of the present embodiment has a substantially constant flow passage cross-sectional area.

  The branch cooling passage 4C has two portions (hereinafter, referred to as “vertical passages 41 and 42”) extending in the vertical direction between the lower boss portion 19 and the exhaust port 7 as viewed from the front of the fastening surface 15A. It is provided to pass through. Further, the branch cooling passage 4C is provided such that a portion passing through the upper side of the exhaust port 6 (hereinafter referred to as “lateral passage 43”) passes through the exhaust port 7 side of the upper boss portion 19. With such an arrangement of the branch cooling passage 4 </ b> C, the heat of the exhaust from the exhaust port 7 is suppressed from being transmitted to the screw holes 20 of the boss portions 19.

  Note that the branch cooling passage 4C of the present embodiment is inclined with respect to the lower cooling passage 4B so that the distance between the left and right of the two vertical passages 41 and 42 becomes narrower toward the upper side (in a C shape). ) Is provided. That is, by the branch cooling passage 4C, an isosceles trapezoidal channel whose upper base is shorter than the lower base when viewed from the front of the fastening surface 15A is formed around the collecting portion outlet portion 6B of the exhaust port 6. Even with such a shape, the cooling water easily flows into the branch cooling passage 4C.

  The branch cooling passage 4C is formed so as not to join the upper cooling passage 4A. In the present embodiment, as shown in FIG. 5A, the upper cooling passage 4A is formed in a concave shape in the direction away from the exhaust port 7 in the vicinity of the collective portion outlet portion 6B of the exhaust port 6, and this concave shape The lateral passage 43 of the branch cooling passage 4 </ b> C is disposed in this portion. A wall portion 18 through which cooling water does not flow is provided between the upper cooling passage 4A and the branch cooling passage 4C (lateral passage 43). The branch cooling passage 4C is isolated from the upper cooling passage 4A by the wall portion 18. The branch cooling passage 4C of the present embodiment is formed, for example, by drilling from the upper surface or lower surface of the overhanging portion 14 and from the rear side of the engine 10 and sealing unnecessary openings with plugs.

  As shown in FIGS. 5B and 6B, the lower cooling passage 4B is provided with an inlet portion 4d and an outlet portion 4e of the branch cooling passage 4C. A portion (hereinafter referred to as “divided flow”) branched from the flow of cooling water flowing through the lower cooling passage 4B (hereinafter referred to as “main flow”) flows into the inlet portion 4d. From the outlet 4e, the cooling water that has flowed through the branch cooling passage 4C flows out, and merges with the cooling water that flows through the lower cooling passage 4B. The inlet portion 4d and the outlet portion 4e of the present embodiment are disposed between the two screw holes 20 provided on the lower side of the fastening surface 15A and outside the cylinder head 1 from the tip of the screw hole 20. The lower cooling passage 4B has a shape that bypasses the screw hole 20 on the front side, and the inlet portion 4d is located at the tip of this bypassed portion (hereinafter referred to as “the bypass portion 46”).

  The lower cooling passage 4B of the present embodiment is provided with a guide portion 17 that guides the cooling water to the branch cooling passage 4C. The guide portion 17 is arranged on the cooling water outlet 45 side (downstream side in the flow direction of the cooling water) from the inlet portion 4d, and the outer wall portion of the cylinder head 1 that forms the lower cooling passage 4B (that is, the extension portion 14). It is provided as a protrusion protruding inward from the side wall portion. As shown in FIG. 4, since the cooling water does not flow at the position where the guide portion 17 is provided, the guide portion 17 forms a flow path toward the inlet portion 4 d.

  As shown in FIG. 5 (B), the guide portion 17 of the present embodiment projects from the outer wall portion of the cylinder head 1 in an oblique direction toward the front side. The surface of the guide portion 17 on the inlet portion 4d side is curved so as to form a flow passage having a substantially constant flow passage cross-sectional area with the bypass portion 46. Thereby, the flow of the cooling water from the front side is smoothly guided to the inlet 4d. Furthermore, the guide portion 17 is provided so as to narrow the main channel cross-sectional area of the lower cooling passage 4B. As described above, the guide portion 17 of the present embodiment is configured to divide the flow of the cooling water flowing through the lower cooling passage 4B into the main flow and the split flow, increase the main flow velocity, and ensure the flow rate of the split flow.

[3. Action, effect]
(1) According to the cylinder head 1 described above, the outlet portion 6B of the exhaust port 6 (manifold) can be cooled by the branch cooling passage 4C, so that the exhaust discharged from the exhaust port 6 is efficiently cooled. be able to. Further, since the branch cooling passage 4C is branched from one of the two cooling passages 4A and 4B and then returns to the original cooling passage 4A and 4B, the cooling water temperature in the two cooling passages 4A and 4B. Can be suppressed. Thereby, the cooling property of the whole exhaust port 6 (the whole manifold) can be stabilized. In the cylinder head 1 described above, since the two cooling passages 4A and 4B are arranged so as to sandwich the exhaust port 6 between the upper and lower sides, the cooling efficiency around the exhaust port 6 built in the cylinder head 1 is improved. Can be improved.

(2) In the cylinder head 1 described above, the lower cooling passage 4B where the branch cooling passage 4C branches and merges has the guide portion 17 for guiding the cooling water to the branch cooling passage 4C. Cooling water can easily flow in, and the cooling efficiency of exhaust can be improved.
(3) Further, the above-described guide portion 17 is disposed downstream of the inlet portion 4d of the branch cooling passage 4C in the flow direction of the cooling water and inward from the outer wall portion of the cylinder head 1 forming the lower cooling passage 4B. It is provided as a protruding protrusion. For this reason, the cooling water can be efficiently guided to the inlet portion 4d of the branch cooling passage 4C, and the exhaust cooling efficiency can be further improved.

  (4) In the cylinder head 1 described above, one screw hole 20 formed in the fastening surface 15A of the flange portion 15 is disposed on the upper side of the exhaust port 7 and two on the lower side. A fastener is fastened to the screw hole 20. In the cylinder head 1 described above, the periphery of the collective portion outlet portion 6B of the exhaust port 6 is cooled by the cooling water flowing through the branch cooling passage 4C, so that the periphery of the screw hole 20 can also be cooled. The tightening force of the tool can be improved. In the cylinder head 1 described above, one screw hole 20 is provided on the upper side and two screw holes 20 on the lower side, so that the exhaust pipe can be fastened with a minimum number of fasteners.

  (5) The above-described branch cooling passage 4C branches off from the lower cooling passage 4B arranged along the lower surface of the exhaust port 6, and passes through the exhaust port 7 side of the upper screw hole 20 and passes through the lower cooling passage. Join 4B. That is, the lateral passage 43 is disposed between the upper screw hole 20 and the collecting portion outlet portion 6 </ b> B of the exhaust port 6. For this reason, while being able to suppress transmission of the heat of the exhaust_gas | exhaustion discharged | emitted from the exhaust port 7, the cooling efficiency of the screw hole 20 can be improved and the fastening force of a fastener can be improved more.

[4. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
The configuration of the branch cooling passage 4C described above is an example, and is not limited to the above. For example, the two vertical passages 41 and 42 may be provided in a direction orthogonal to the lower cooling passage 4B. One or both of the inlet portion 4d and the outlet portion 4e may be provided on the outer side (front side and rear side) of the lower screw hole 20. The lateral passage 43 may be disposed above or below the upper cooling passage 4A, or may be provided at a position that interferes with the upper screw hole 20 when viewed from the front of the fastening surface 15A. Good.

  Further, as shown in FIG. 7, the branch cooling passage 4C may not be branched from the downstream cooling passage 4B. That is, the cylinder head 1 may have a branch cooling passage 4C ′ that branches from the upper cooling passage 4A and joins the upper cooling passage 4A again through the periphery of the outlet portion 6B of the exhaust port 6. In this case, the upper cooling passage 4A is provided with an inlet portion 4d 'and an outlet portion 4e' of the branch cooling passage 4C '. Since the temperature of the cooling water flowing through the upper cooling passage 4A tends to be lower than the temperature of the cooling water flowing through the lower cooling passage 4B, the cooling efficiency of the exhaust is improved by providing the branch cooling passage 4C ′. be able to.

  In the case of this configuration, by providing a guide portion 17 similar to the guide portion 17 described above in the upper cooling passage 4A, the inflow of cooling water to the branch cooling passage 4C ′ can be promoted. However, the structure of the guide part 17 mentioned above is an example, Comprising: It is not restricted to what was mentioned above. Moreover, the guide part 17 is not an essential structure and can be omitted. When the guide portion 17 is omitted, for example, the opening area of the inlet portion 4d of the branch cooling passage 4C may be increased so that the cooling water can easily flow. Further, the flow passage cross-sectional area of the branch cooling passage 4C may not be constant, and for example, the flow passage cross-sectional areas of the vertical passages 41 and 42 may be formed so as to gradually decrease toward the outlet side.

Further, the positional relationship between the upper and lower cooling passages 4A and 4B and the boss portion 19 (screw hole 20) is not limited to that described above. For example, when viewed from the front of the fastening surface 15A, the upper cooling passage 4A may be disposed at a position where it interferes with the upper screw hole 20, or may be disposed above the upper screw hole 20. Similarly, the lower cooling passage 4 </ b> B may be disposed at a position where it does not interfere with the lower screw hole 20.
The shape of the flange portion 15 and the arrangement and number of the boss portions 19 (screw holes 20) are not limited to those described above. Further, the flow direction of the cooling water in the cooling passages 4A and 4B may be a direction from the rear side to the front side. Further, the number of cylinders of the engine 10 and the position of the exhaust port 7 of the cylinder head 1 are not limited to the above-described configuration.

DESCRIPTION OF SYMBOLS 1 Cylinder head 4 Exhaust side cooling path 4A Upper side cooling path 4B Lower side cooling path 4C, 4C 'Branch cooling path 4d, 4d' Inlet part 4e, 4e 'Outlet part 6 Exhaust port (manifold)
6B Collecting part outlet part 7 Exhaust port (opening)
10 Engine 15A Fastening surface 17 Guide part 18 Wall part 20 Screw hole

Claims (6)

In the cylinder head with a built-in engine exhaust manifold,
Two cooling passages arranged so that the cooling water circulates inside and sandwiches the manifold from above and below,
A branch cooling passage through which the cooling water circulates, branches from one of the two cooling passages, and merges with the one cooling passage through the periphery of the manifold outlet portion;
An engine cylinder head, comprising: 2. The engine cylinder head according to claim 1, wherein the one cooling passage has a guide portion that guides the cooling water to the branch cooling passage. 3. The cooling water in the one cooling passage flows from one of the front side and the rear side of the engine to the other;
The guide portion is disposed on the downstream side in the flow direction of the cooling water from the inlet portion of the branch cooling passage, and is a protrusion protruding inward from the outer wall portion of the cylinder head forming the one cooling passage. The cylinder head of the engine according to claim 2, wherein the cylinder head is provided. A screw hole drilled in the fastening surface of the cylinder head and the exhaust pipe;
One of the screw holes is disposed above the opening at the downstream end of the manifold, and two are disposed below the opening. 4. The cylinder head of the engine according to item 1. The branch cooling passage branches from a lower cooling passage disposed along the lower surface of the manifold, and merges with the lower cooling passage through the opening side of the upper screw hole. The cylinder head of the engine according to claim 4. 5. The engine cylinder head according to claim 1, wherein the branch cooling passage joins after branching from an upper cooling passage disposed along the upper surface of the manifold.

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