JP6834166B2 - Engine cylinder head - Google Patents

Description

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

Conventionally, a cylinder head and an exhaust system manifold have been integrally formed so that a plurality of exhaust ports connected to the combustion chamber of an engine merge in the cylinder head. In such a cylinder head, the distance between the exhaust purification catalyst interposed in the exhaust system and the engine is shortened, so that the exhaust purification performance can be improved and the length of the exhaust system itself is shortened. It has the advantages of reducing exhaust pressure loss and facilitating space saving of the engine. On the other hand, such a cylinder head has a drawback that it tends to receive high temperature due to exhaust heat as compared with a cylinder head having a manifold separately provided. Therefore, it has been proposed to improve the cooling performance by circulating the engine cooling water around the exhaust port or near the outlet of the manifold (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-309158

By the way, the vicinity of the outlet of the manifold built in the cylinder head is a portion where the exhaust gas flowing through each exhaust port gathers, so that the temperature tends to be particularly high. On the other hand, if a flow path through which cooling water flows is provided near the outlet, the cooling property of this portion can be ensured. However, since the temperature changes significantly in the vicinity of this outlet, simply providing a cooling passage may affect the cooling performance of other parts of the manifold.

This case was devised in view of such a problem, and one of the purposes is to provide a cylinder head of an engine capable of stabilizing the cooling performance of the entire manifold. Not limited to this purpose, it is also an action and effect derived by each configuration shown in the embodiment for carrying out the invention described later, and it is also for another purpose of this case to exert an action and effect that cannot be obtained by the conventional technique. is there.

(1) The cylinder head of the engine disclosed here is a cylinder head having a built-in manifold of the exhaust system of the engine, and two coolings arranged so as to allow cooling water to flow inside and sandwich the manifold from above and below. The passage and the cooling water flow through the inside, branch off from the cooling passage located on one side of the manifold in the vertical direction, and do not merge with the cooling passage located on the other side in the vertical direction. It is provided with a branch cooling passage that passes around the collecting portion outlet portion and joins the one cooling passage so as to pass through the other side of the collecting portion outlet portion in the vertical direction of the manifold.

(2) It is preferable that one of the cooling passages has a guide portion for guiding the cooling water to the branch cooling passage.
(3) It is preferable that the cooling water in the one cooling passage circulates 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 arranged on the downstream side of the inlet portion of the branch cooling passage in the flow direction of the cooling water, and is projected inward from the outer wall portion of the cylinder head forming the one cooling passage. It is preferable to provide it as a protrusion.

(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 are arranged below the opening.
(5) The branch cooling passage branches from the lower cooling passage arranged along the lower surface of the manifold, and joins the lower cooling passage through the opening side of the upper screw hole. Is preferable.
(6) Alternatively, it is preferable that the branch cooling passage branches from the upper cooling passage arranged along the upper surface of the manifold and then merges.

Since the branched cooling passage that passes around the outlet of the collecting portion of the manifold returns to the branched cooling passage, it is possible to suppress changes in the cooling water temperature in the two cooling passages. As a result, the cooling performance of the entire manifold can be stabilized.

It is a perspective view which illustrates the cylinder head and the cylinder block of the engine which concerns on embodiment. It is a schematic vertical sectional view of an engine. It is a horizontal sectional view which shows the shape of the exhaust port in a cylinder head. It is a perspective view which shows the cooling passage of the exhaust side in a cylinder head. (A) is a horizontal sectional view showing the upper part (upper cooling passage) of the cooling passage of FIG. 4, and (B) is a horizontal sectional view showing the lower part (lower cooling passage) of the cooling passage of FIG. (A) is a view of the fastening surface of the cylinder head viewed from the front, and (B) is a schematic view for explaining the configuration of the cooling passage of FIG. 6 (A). It is a schematic diagram for demonstrating the structure of the cooling passage provided in the cylinder head which concerns on a modification.

The cylinder head of the engine as an embodiment will be described with reference to the drawings. Each of the embodiments shown below is merely an example, and there is no intention of excluding the application of various modifications and techniques not specified in each of the following embodiments. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed, or can be combined as appropriate.

[1. overall structure]
The cylinder head 1 of the present embodiment is an exhaust manifold integrated cylinder head having a built-in exhaust system manifold (multi-branch pipe), and is attached to the cylinder block 2 of the water-cooled multi-cylinder engine 10. In the following description, the side where the cylinder block 2 is fixed to the cylinder head 1 is downward, and the opposite side is upward. A plurality of cylinders 3 are arranged in a row inside the engine 10. An example shown in FIG. 1 is a three-cylinder (# 1, # 2, # 3 in order from the front side) engine 10 in which three cylinders 3 are arranged in series. Hereinafter, the rowing direction of the cylinder 3 is represented by reference numeral L.

As shown in FIGS. 1 and 2, a cooling passage 30 (water jacket) dug in a curved surface along the cylinder surface 3B is formed around the cylinder 3. The upper part of the cooling passage 30 is opened on the upper surface of the cylinder block 2 and communicates with the cooling passage 4 (4B) on the exhaust side and the cooling passage 5 on the intake side formed inside the cylinder head 1, respectively. As a result, the outer peripheral portion of the exhaust port 6 is also cooled by the 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 designated, but these cooling passages 4 and 5 are integrated inside the cylinder head 1. Provided.

As shown in FIG. 2, a recess serving as a ceiling surface 3A (ceiling surface of a combustion chamber) is formed on the lower surface of the cylinder head 1, and an exhaust port 6 is connected to each combustion chamber. The exhaust port 6 is a multi-branch type exhaust flow path that functions as a manifold of the exhaust system. 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 inside the cylinder head 1. Hereinafter, the integrated portion of the exhaust port 6 will be referred to as an exhaust collecting portion 6A.

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

As shown in FIG. 6A, a flange portion 15 having a flat fastening surface 15A perpendicular to the flow direction of the exhaust gas is formed around the exhaust port 7. The flange portion 15 is a portion where an exhaust pipe (including a pipe material for connection with a catalyst device, a turbocharger, etc.) on the downstream side (not shown) 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 top, bottom, left, and right 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 provided 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 perpendicular to the fastening surface 15A. The positions of the boss portions 19 are set at predetermined intervals 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 are formed on the lower side of the fastening surface 15A arranged in an annular shape.

The upper boss portion 19 (screw hole 20) is arranged above the exhaust port 7 (substantially directly 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 two lower boss portions 19 (screw holes 20) are arranged on the left and right sides of the exhaust port 7 (approximately equidistant from the center point P of the exhaust port 7) below the exhaust port 7. Of these boss portions 19, the boss portion 19 located on the upper side is formed so that the upper end of each boss portion 19 bulges slightly above the upper surface 14A of the overhanging portion 14. On the other hand, in the boss portion 19 located on the lower side, the lower end of each boss portion 19 substantially coincides with the lower surface 14B of the overhanging portion 14 (so that the lower end does not protrude downward from the lower surface 14B of the overhanging portion 14). It is formed.

[2. Cooling passage]
FIG. 4 illustrates the shape of the cooling passage 4 (water jacket) on the exhaust side inside the cylinder head 1. The exhaust port 6 is sandwiched between the cylinder head 1 as a cooling passage 4 through which cooling water for cooling the periphery of the exhaust port 6 (the manifold of the exhaust system 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 4C for cooling the collecting portion outlet portion 6B of the exhaust port 6.

In the cylinder head 1 of the present embodiment, a cooling water inlet 44 to 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. Therefore, the cooling water flows from the front side to the rear side in each of the cooling passages 4A and 4B. The upper cooling passage 4A and the lower cooling passage 4B of the exhaust port 6 are arranged along the upper surface and the lower surface of the exhaust port 6. 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 of each other in the overhanging portion 14, and are substantially relative to the upper surface 14A and the lower surface 14B of the overhanging portion 14. It is provided in a plane so as to be parallel.

5 (A) and 5 (B) show cross-sectional views of the upper and lower cooling passages 4A and 4B cut by a plane substantially parallel to the upper surface 14A and the lower surface 14B of the overhanging portion 14. The alternate long and short dash line in FIGS. 5A and 5B corresponds to the contour of the ceiling surface 3A of the cylinder 3. Each of the cooling passages 4A and 4B in the overhanging portion 14 has a shape in which the cooling water meanders while branching or merging and flows to the rear side. Further, as shown in FIG. 6A, the upper cooling passage 4A of the present embodiment is arranged below the screw hole 20 so as not to interfere with the upper screw hole 20 provided on the fastening surface 15A. To. 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 is one of the flow paths that branches from one of the upper and lower cooling passages 4A and 4B, passes around the collecting portion outlet portion 6B of the exhaust port 6, and joins the original cooling passages 4A and 4B. It is a part, and the cooling water flows through the inside to cool the collecting part outlet part 6B of the exhaust port 6. As shown in FIG. 3, the collecting portion outlet portion 6B referred to here means a portion closer to the downstream side of the exhaust collecting portion 6A and 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 around the collecting portion outlet portion 6B of the exhaust port 6, and is again on the lower side. It joins 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 the cooling water of the lower cooling passage 4B again. Join in. Specifically, the branch cooling passage 4C branches from the exhaust port 7 side of the front side boss portion 19 in the lower cooling passage 4B, and is on the front side, upper side, and rear side of the collecting portion outlet portion 6B of the exhaust port 6. After passing through in this order, they merge at the exhaust port 7 side of the rear side boss portion 19 in the lower cooling passage 4B. The branch cooling passage 4C of the present embodiment is formed so that the cross-sectional area of the passage is substantially constant.

In the branch cooling passage 4C, two portions extending in the vertical direction (hereinafter referred to as "vertical passages 41 and 42") are between the lower boss portion 19 and the exhaust port 7 when viewed from the front of the fastening surface 15A. It is provided to pass through. Further, the branch cooling passage 4C is provided so that a portion passing above the exhaust port 6 (hereinafter referred to as “horizontal passage 43”) passes through the exhaust port 7 side with respect to the upper boss portion 19. By such an arrangement of the branch cooling passage 4C, the heat of the exhaust gas from the exhaust port 7 is suppressed from being transferred to the screw holes 20 of each boss portion 19.

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

The branch cooling passage 4C is formed so as not to merge with 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 vicinity of the collecting portion outlet 6B of the exhaust port 6 in a direction away from the exhaust port 7. The lateral passage 43 of the branch cooling passage 4C is arranged in the portion of. 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 (horizontal 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 by, for example, drilling holes from the upper surface or the 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 part (hereinafter referred to as "branch flow") branched from the flow of cooling water (hereinafter referred to as "mainstream") flowing through the lower cooling passage 4B flows into the inlet portion 4d. The cooling water flowing through the branch cooling passage 4C flows out from the outlet portion 4e and joins the flow of the cooling water flowing through the lower cooling passage 4B. The inlet portion 4d and the outlet portion 4e of the present embodiment are arranged 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 holes 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 the bypassed portion (hereinafter referred to as “detour portion 46”).

The lower cooling passage 4B of the present embodiment is provided with a guide portion 17 for guiding 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) with respect to the inlet portion 4d, and is an outer wall portion (that is, an overhanging portion 14) of the cylinder head 1 forming the lower cooling passage 4B. 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 4d.

As shown in FIG. 5B, the guide portion 17 of the present embodiment projects obliquely from the outer wall portion of the cylinder head 1 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 path having a substantially constant flow path cross-sectional area with the bypass portion 46. As a result, the flow of the cooling water from the front side is smoothly guided to the inlet portion 4d. Further, the guide portion 17 is provided so as to narrow the cross-sectional area of the main stream 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 stream and the split stream, increase the flow velocity of the main stream, and secure the flow rate of the split stream.

[3. Action, effect]
(1) According to the cylinder head 1 described above, the branch cooling passage 4C can cool the collecting portion outlet 6B of the exhaust port 6 (manifold), so that the exhaust discharged from the exhaust port 6 is efficiently cooled. be able to. Further, since the branched cooling passage 4C is configured to branch from one of the two cooling passages 4A and 4B and then return to the original cooling passages 4A and 4B, the cooling water temperature in the two cooling passages 4A and 4B It is possible to suppress the change of. As a result, the cooling performance of the entire exhaust port 6 (entire manifold) can be stabilized. Since the cylinder head 1 described above has two cooling passages 4A and 4B arranged so as to sandwich the exhaust port 6 above and below, the cooling efficiency around the exhaust port 6 built in the cylinder head 1 can be improved. Can be improved.

(2) In the cylinder head 1 described above, since the lower cooling passage 4B to which the branch cooling passage 4C branches and joins has a guide portion 17 for guiding the cooling water to the branch cooling passage 4C, the branch cooling passage 4C has a guide portion 17. The cooling water can easily flow in, and the cooling efficiency of the exhaust can be improved.
(3) Further, the above-mentioned guide portion 17 is arranged on the downstream side in the cooling water flow direction from the inlet portion 4d of the branch cooling passage 4C, and from the outer wall portion of the cylinder head 1 forming the lower cooling passage 4B to the inside. It is provided as a protruding protrusion. Therefore, the cooling water can be efficiently guided to the inlet portion 4d of the branch cooling passage 4C, and the cooling efficiency of the exhaust gas 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 arranged above the exhaust port 7 and two are arranged below the exhaust port 7. The fastener is fastened to the screw hole 20. In the cylinder head 1 described above, since the periphery of the collecting portion outlet portion 6B of the exhaust port 6 is cooled by the cooling water flowing through the branch cooling passage 4C, the periphery of the screw hole 20 can also be cooled, thereby fastening. The tightening force of the tool can be improved. Since the cylinder head 1 described above is provided with one screw hole 20 on the upper side and two screw holes 20 on the lower side of the exhaust port 7, the exhaust pipe can be fastened with the minimum number of fasteners.

(5) The above-mentioned branch cooling passage 4C branches 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 to the lower cooling passage. Join 4B. That is, the lateral passage 43 is arranged between the upper screw hole 20 and the collecting portion outlet portion 6B of the exhaust port 6. Therefore, the heat transfer of the exhaust gas discharged from the exhaust port 7 can be suppressed, the cooling efficiency of the screw hole 20 can be improved, and the tightening force of the fastener can be further improved.

[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 can be variously modified and implemented 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 that described above. For example, the two vertical passages 41 and 42 may be provided in a direction orthogonal to the lower cooling passage 4B. Further, one or both of the inlet portion 4d and the outlet portion 4e may be provided on the outside (front side and rear side) of the lower screw hole 20. Further, the lateral passage 43 may be arranged above or below the upper cooling passage 4A, or may be provided at a position where it 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 does not have to 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, passes around the gathering portion outlet portion 6B of the exhaust port 6, and rejoins the upper cooling passage 4A. 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 the same guide portion 17 as the guide portion 17 described above in the upper cooling passage 4A, the inflow of cooling water into the branch cooling passage 4C'can be promoted. However, the configuration of the guide unit 17 described above is an example, and is not limited to the configuration described above. Further, the guide unit 17 is not an essential configuration 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 into the guide portion 17. Further, the flow path cross-sectional area of the branch cooling passage 4C does not have to be constant, and for example, the flow path 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 arranged at a position where it interferes with the upper screw hole 20, or may be arranged above the upper screw hole 20. Similarly, the lower cooling passage 4B may be arranged 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 the 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.

1 Cylinder head 4 Exhaust side cooling passage 4A Upper cooling passage 4B Lower cooling passage 4C, 4C'Branch cooling passage 4d, 4d' Inlet part 4e, 4e' Outlet part 6 Exhaust port (manifold)
6B Meeting part Exit 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 that incorporates the manifold of the engine exhaust system
Two cooling passages arranged so that the cooling water circulates inside and sandwiches the manifold from above and below,
The cooling water flows through the inside, branches off from the cooling passage located on one side of the manifold in the vertical direction, and does not merge with the cooling passage located on the other side in the vertical direction of the manifold. A branch cooling passage that passes around the collecting portion outlet so as to pass through the other side in the vertical direction of the collecting portion outlet and joins the one cooling passage.
The cylinder head of the engine is characterized by being equipped with. The cylinder head of an engine according to claim 1, wherein one of the cooling passages has a guide portion for guiding the cooling water to the branch cooling passage. 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 arranged on the downstream side in the flow direction of the cooling water from the inlet portion of the branch cooling passage, and serves as a protrusion projecting 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 is provided in the fastening surface between the cylinder head and the exhaust pipe.
Any of claims 1 to 3, characterized in that one screw hole is arranged above the opening at the downstream end of the manifold and two are arranged below the opening. The cylinder head of the engine according to item 1. The branch cooling passage is characterized in that it branches from the lower cooling passage arranged along the lower surface of the manifold and joins the lower cooling passage through the opening side of the upper screw hole. The cylinder head of the engine according to claim 4. The cylinder head of an engine according to any one of claims 1 to 4, wherein the branch cooling passage branches from an upper cooling passage arranged along the upper surface of the manifold and then merges.

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