Engine

Abstract

To solve a problem that a pocket part of an upward-facing opening exists at an upper part of an exhaust manifold attachment surface and water accumulating in the pocket part causes corrosion with a simple structure.SOLUTION: In a portion between adjacent exhaust ports 4 on an exhaust side surface of a cylinder head 2, a recessed part 24 recessed downward relative to an exhaust manifold attachment surface 5 exists and the recessed part 24 is closed by a gasket 6 to form a pocket part 25. An opening 26 is formed at a portion, which is located at a lower end of the recessed part 24, of the gasket 6, and a portion, which corresponds to the recessed part 24, of a flange plate 9 of an exhaust manifold 7 is formed as a relief surface 28 which does not adhere to the gasket 6. A gap 29 communicating with the opening 26 is formed between the gasket 6 and the relief surface 28. Water in the pocket part 25 flows downward from the opening 26 through the gap 29. Thus, corrosion of a member does not occur.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an engine in which an exhaust manifold is fixed to a cylinder head via a gasket.

Background Art

[0002] When fixing an exhaust manifold to the exhaust side surface of a cylinder head, an adapter for cooling exhaust gas with cooling water may be interposed between the exhaust side surface and the exhaust manifold. In this case, however, cooling water may leak from the cooling water inlet of the adapter. Therefore, Patent Document 1 discloses that in order to prevent the cooling water leaking from the adapter from flowing down to the exhaust manifold and impairing the aesthetic appearance, the exhaust manifold is formed in a bifurcated shape to allow the cooling water to flow down to the bifurcated portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Now, in a multi-cylinder engine using an external exhaust manifold, an exhaust manifold mounting surface is formed on the exhaust side surface of the cylinder head. The exhaust manifold mounting surface is long in the crankshaft axis direction so as to surround a group of exhaust ports, and the exhaust manifold is fixed to this exhaust manifold mounting surface via a gasket.

[0005] The exhaust manifold mounting surface of the cylinder head is formed as a flat surface. However, in the exhaust side surface, excluding the exhaust manifold mounting surface, there are irregularities due to the structure of the exhaust passage, the structure of the water jacket, etc. There may be a valley-shaped recess in the portion between adjacent exhaust ports, with the upper end of the exhaust manifold mounting surface being scooped downward. Then, an upward pocket portion is formed between the recess of the cylinder head and the gasket.

[0006] In an engine for an automobile, when driving, rainwater may enter the pocket portion, or water splashed up by the wheels during driving in the crown water channel may enter the pocket portion, or washing water may enter the pocket portion. Therefore, there was a risk that water would accumulate in the pocket portion and corrode the cylinder head, the gasket, and the exhaust manifold.

[0007] The present invention aims to improve such a situation.

Means for Solving the Problem

[0008] The present invention relates to "an engine having a cylinder head with an exhaust manifold mounting surface formed on the exhaust side surface and an exhaust manifold whose flange plate is fixed to the exhaust manifold mounting surface via a gasket, wherein a valley-shaped recess opening upward is formed in the exhaust manifold mounting surface, and an upward-opening pocket portion is formed by the recess being blocked by the gasket." Regarding such an engine, this engine, as described in claim 1, "an opening communicating with at least the lower end of the pocket portion is formed in the gasket being and a gap communicating with the opening and opening at least downward is formed between the flange plate of the exhaust manifold and the gasket formed, said gap the flange plate of the exhaust manifold a part of the gasket in a direction away from"formed by being offset" It has the following structure.

[0009] The invention of the present application also includes the configuration of claim 2. This invention "The pocket portion is located between adjacent exhaust ports, and the lower end of the pocket portion and the opening are below the exhaust manifold mounting surface upper end of the cylinder head." It has the following structure.

[0010] In the invention of the present application, the opening of the gasket may be a hole having a closed inner circumference or an upwardly opening cut groove. In any case, the opening only needs to communicate with the lower end of the pocket portion, and the size and shape can be arbitrarily set.

Advantages of the Invention

[0011] In the invention of the present application, due to the formation of a recess in the exhaust manifold mounting surface of the cylinder head, a pocket portion is formed between the cylinder head and the gasket. Even if water enters this pocket portion, the water flows downward through the gap from the opening located at the lower end of the pocket portion, and water does not accumulate in the pocket portion. Therefore, corrosion of the cylinder head, gasket, and exhaust manifold can be prevented.

[0012] In the exhaust side portion of the cylinder head, due to the need to form the meat portion around the exhaust port with equal thickness, etc., there are often recesses between adjacent exhaust ports in the upper part of the exhaust manifold mounting surface. Claim 2 is applied to this form, and while making the cylinder head have a reasonable structure, it can prevent corrosion caused by water accumulating in the pocket portion. Therefore, it has high practical applicability.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0014] Next, embodiments of the present invention will be described with reference to the drawings. This embodiment is applied to a three-cylinder engine for an automobile. Regarding the engine, the crankshaft axis direction is often referred to as the front-rear direction, and this common naming convention is also followed in this embodiment. The direction facing the exhaust side surface of the cylinder head is the side view direction. The engine of this embodiment has a crankshaft in a posture that is long in the vehicle body width direction and the exhaust side surface is directed forward of the vehicle body. Therefore, it is arranged in the engine room at the front of the vehicle body in a state of transverse front exhaust.

[0015] (1). Basic Structure As shown in FIGS. 1 and 4(A), the engine includes a cylinder block 1, a cylinder head 2 fixed to the upper surface thereof, and a head cover 3 fixed to the upper surface of the cylinder head 2. As shown in FIG. 2, on the exhaust side surface of the cylinder head 2 three exhaust ports 4 are formed side by side in the crankshaft axis direction, and on the exhaust side surface, a flat exhaust manifold mounting surface 5 surrounding the three exhaust ports 4 is formed in a state that is long in the front-rear direction. In FIG. 3(B), parallel oblique lines are shown on the exhaust manifold mounting surface 5 to clarify the range. The parallel oblique lines in FIG. 2 also indicate a flat surface.

[0016] And an exhaust manifold 7 is fixed to the exhaust manifold mounting surface 5 via a gasket 6 made of metal or inorganic material. As shown in FIG. 4(A), the exhaust manifold 7 is surrounded by a heat shield (insulator) 8 from the side.

[0017] As can be understood from FIG. 1, the exhaust manifold 7 has a flange plate 9 that overlaps the gasket 6 and three branch pipes 10 joined thereto. The three branch pipes 10 converge into one and join the upper cone portion of the catalyst case 12 to the converging portion 11. As can be understood from FIG. 4(A), the hollow portion formed by the branch pipes 10 and the converging portion 11 is made by overlapping two sheets of plate material, the two sheets of plate material formed in are fixed by welding the flange-shaped edge pieces 13.

[0018] Note that a boss portion 14 for attaching an O2 sensor is provided on the upper cone portion of the catalyst case 12. Further, the pedestal 15 provided on the converging portion 11 of the exhaust manifold 7 is for attaching the heat shield plate 8, as can be understood from FIG. 4(A).

[0019] As can be understood from FIGS. 1 and 2, the flange plate 9 of the exhaust manifold 7 is fixed to the exhaust manifold mounting surface 5 of the cylinder head 2 with bolts 16 at a total of five locations, three at the upper part and two at the lower part. Therefore, five boss portions 17 that are flush with the exhaust manifold mounting surface 5 are formed on the exhaust side surface of the cylinder head 2 so as to protrude upward and outward, and tap holes 18 are formed in each boss portion 17.

[0020] In FIG. 1, the bolt 16 is shown simplified as a hexagonal bolt, but actually, as shown in FIG. 4(A), a stud bolt is used as the bolt 16, and the exhaust manifold 7 is fixed with nuts 16a screwed onto the stud bolts. As shown in FIG. 1, bracket pieces 19 in an inclined posture are fixed by welding to the upper end and the left and right ends of the flange plate 9 of the exhaust manifold 7. The bracket pieces 19 are for attaching the heat shield plate 8. Therefore, the heat shield plate 8 is fixed to the exhaust manifold 7 at a total of three locations, two at the upper part and one at the lower part. Note that the heat shield plate 8 is fixed with the stud bolts 20 and nuts 21 shown in FIG. 1.

[0021] (2). Drainage structure As can be understood from FIGS. 2 and 4(A), upper and lower water jackets 22 and 23 are formed inside the portion of the cylinder head 2 between adjacent exhaust ports 4. At the location of the upper water jacket 22, a valley-shaped recess 24 that is recessed inward is formed on the exhaust side surface of the cylinder head 2, and the lower end 24a of the recess 24 extends to a position slightly higher than the vertical middle height of the exhaust port 4. For this reason, the recess 24 is formed in a state of entering downward from the upper surface of the exhaust manifold mounting surface 5.

[0022] On the other hand, as shown in FIG. 3(A), the gasket 6 is formed to cover the entire exhaust manifold mounting surface 5, and the flange plate 9 of the exhaust manifold 7 is also in substantially the same form as the gasket 6. For this reason, the recess 24 is blocked by the gasket 6, and a pocket portion 25 that opens upward is formed.

[0023] For this reason, there is a risk that rainwater may enter the pocket portion 25 during rainy driving, water splashed up by the wheels during driving on a crown waterway may enter the pocket portion 25, or cleaning water during high-pressure cleaning may enter the pocket portion 25. Then, there is a risk that the cylinder head 2, the gasket 6, and the flange plate 9 may corrode over a long period of use.

[0024] Regarding this point, in the present embodiment, first, an opening (through hole) 26 is formed in the portion of the gasket 6 that faces the lower end 24a of the recess 24 of the cylinder head 2. On the other hand, for the flange plate 9 of the exhaust manifold 7, the overlapping surface 27 that overlaps with the gasket 6 is made independent for each exhaust port 4, and the portion between adjacent overlapping surfaces 27 is formed as a relief surface 28 that is displaced in a direction away from the gasket 6, and a gap 29 that communicates with the opening 26 and is vertically opened is formed between the gasket 6 and the relief surface 28.

[0025] As can be understood from FIGS. 3 and 4(B), outward reinforcing ribs 30 are formed on the outer periphery of the flange plate 9. Further, the flange plate 9 is formed by bending and protruding a single material plate, and the overlapping surface 27 is formed by protruding (bulging) the material plate to the side opposite to the reinforcing rib 30.

[0026] Therefore, the relief surface 28 of the flange plate 9 remains as the material plate. Each overlapping surface 27 has an outward protruding portion 31 that overlaps with the boss portion 17 of the cylinder head 2, and a bolt insertion hole 32 is provided in the outward protruding portion 31. Naturally, the gasket 6 also has a bolt insertion hole 32. Also, as a matter of course, the flange plate 9 of the gasket 6 and the exhaust manifold 7 has a through hole 4a communicating with the exhaust port 4.

[0027] As described above, since the lower end of the pocket portion 25, the opening 26 of the gasket 6, and the gap 29 communicate with each other, even if water enters the pocket portion 25, the water does not accumulate in the pocket portion 25 but flows down below the exhaust manifold 7. Therefore, corrosion of the cylinder head 2, the gasket 6, and the exhaust manifold 7 can be prevented.

[0028] In the embodiment, the relief surface 28 extends in the outer peripheral direction of the flange plate 9. This is because each overlapping surface 27 is formed to have as uniform a width as possible to equalize the surface pressure of each overlapping surface 27 after fastening. Therefore, although the gap 29 opens in both the upper and lower directions, if it is also opened upward, an air bleeding effect occurs. Thus, the left - right width of the gap 29 can be made as small as possible while enhancing the water drainage property. Also, when each overlapping surface 27 is independent for each exhaust port 4, there is an advantage that the processing error of the flange plate 9 can be absorbed and the adhesion (sealing property) to the exhaust manifold mounting surface 5 can be improved. also There is.

[0029] The overlapping surface 27 protrudes from the relief surface 28. In this aspect, due to the rib effect, the rigidity of each portion of the overlapping surface 27 is significantly increased, so that the sealing property between the gasket 6 and the exhaust port 4 can be further improved.

[0030] The embodiments of the present invention have been described above. However, the present invention can be embodied in various other ways. For example, the target engine is not limited to a three-cylinder engine, and can be widely applied to a two-cylinder or multi-cylinder engine with four or more cylinders. Further, the opening does not necessarily have to be a circular small hole, and it can also be formed in the form of a cutout groove that is similar to the concave portion 24 and opens upward, or in the form of a hole of an appropriate size that is not a small hole.

Industrial Applicability

[0031] The present invention can be embodied in an engine. Therefore, it can be industrially utilized.

Explanation of Reference Numerals

[0032] 2 Cylinder head 4 Exhaust port 5 Exhaust manifold mounting surface 6 Gasket 7 Exhaust manifold 9 Flange plate 10 Branch pipe 11 Collecting portion 12 Catalyst case 16 Bolt 17 Boss portion 18 Tap hole 22, 23 Water jacket 24 Concave portion 24a Lower end 25 Pocket portion 26 Opening 27 Overlapping surface 28 Relief surface 29 Gap (flow-down passage) 32 Bolt insertion hole

Claims

1. A cylinder head having an exhaust manifold mounting surface formed on an exhaust side surface, and an exhaust manifold whose flange plate is fixed to the exhaust manifold mounting surface via a gasket, wherein a valley-shaped recess opening upward is formed in the exhaust manifold mounting surface, and a pocket portion with an upward opening is formed by closing the recess with the gasket, wherein an opening communicating with at least the lower end of the pocket portion is formed in the gasket, and a gap communicating with the opening and opening at least downward is formed between the flange plate of the exhaust manifold and the gasket, wherein the gap is formed by displacing a part of the flange plate of the exhaust manifold in a direction away from the gasket, an engine.

2. The pocket portion is located between adjacent exhaust ports, and the lower end of the pocket portion and the opening are located below the upper end of the exhaust manifold mounting surface, The engine according to claim 1.

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