JP7688062B2 - engine - Google Patents

Description

This invention relates to an engine in which an exhaust manifold is fixed to a cylinder head via a gasket.

When fixing the exhaust manifold to the exhaust side of the cylinder head, an adapter is sometimes placed between the exhaust side and the exhaust manifold to cool the exhaust gas with cooling water. In this case, however, the 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 running down into the exhaust manifold and damaging the aesthetic appearance, the exhaust manifold is formed in a bifurcated shape and the cooling water is made to flow down the bifurcated part.

JP 2011-208604 A

In a multi-cylinder engine that uses an external exhaust manifold, an exhaust manifold mounting surface is formed on the exhaust side of the cylinder head. The exhaust manifold mounting surface is elongated in the crankshaft direction so as to surround the group of exhaust ports, and the exhaust manifold is fixed to this exhaust manifold mounting surface via a gasket.

The exhaust manifold mounting surface of the cylinder head is formed as a flat surface, but the exhaust side surface, excluding the exhaust manifold mounting surface, has unevenness due to the structure of the exhaust passage and the structure of the water jacket, and there may be a valley-shaped recess between adjacent exhaust ports, where the upper end of the exhaust manifold mounting surface is carved downward, and this forms an upward-facing pocket between the recess of the cylinder head and the gasket.

In automobile engines, rainwater can get into the pockets while the vehicle is driving, water splashed up by the wheels while driving on flooded roads can get into the pockets, and cleaning water can get into the pockets. This can cause water to accumulate in the pockets, corroding the cylinder head, gaskets, and exhaust manifold.

The objective of the present invention is to improve this current situation.

The present invention relates to
"A cylinder head having an exhaust manifold mounting surface formed on the exhaust side, and an exhaust manifold having a flange plate fixed to the exhaust manifold mounting surface via a gasket,
An upwardly opening valley-shaped recess is formed in the exhaust manifold mounting surface, and an upwardly opening pocket is formed by sealing the recess with the gasket.
The engine has the following features as claimed in claim 1:
"An opening is formed in the gasket that is in communication with at least the lower end of the pocket portion, and a gap is formed between the flange plate of the exhaust manifold and the gasket that is in communication with the opening and that is open at least downward,
The gap is formed by displacing a portion of the exhaust manifold flange plate in a direction away from the gasket."
The structure is as follows.

The present invention also includes the configuration of claim 2, and the present invention is as follows:
"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 structure is as follows.

In the present invention, the opening of the gasket may be a hole with a closed inner circumference, or a cut groove that opens upward. In either case, the opening only needs to be connected to the lower end of the pocket, and the size and shape can be set as desired.

In the present invention, a pocket is formed between the cylinder head and the gasket due to the formation of a recess on the exhaust manifold mounting surface of the cylinder head. Even if water gets into this pocket, it flows downward through the gap from the opening located at the bottom end of the pocket, and water does not accumulate in the pocket. This prevents corrosion of the cylinder head, gasket, and exhaust manifold.

In the exhaust side of the cylinder head, recesses often exist between adjacent exhaust ports in the upper part of the exhaust manifold mounting surface due to the need to form the material around the exhaust port with an equal thickness. Claim 2 applies to this form, and while providing a rational structure for the cylinder head, it is possible to prevent corrosion caused by water accumulating in the pocket. Therefore, it is highly applicable to reality.

FIG. 2 is a partial side view of an embodiment. FIG. 2 is a partial side view of the cylinder head according to the embodiment. 1A is a front view of the gasket seen from the outside side, and FIG. 1B is a rear view of the exhaust manifold. 3A is a cross-sectional view taken along line IVA-IVA in FIG. 1 and FIG. 2, and FIG. 3B is a cross-sectional view taken along line IVB-IVB in FIG. 2 and FIG. 3B.

Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a three-cylinder engine for an automobile. With regard to engines, the crankshaft direction is often referred to as the front-rear direction, and this common terminology is followed in this embodiment. The direction facing the exhaust side of the cylinder head is the side view direction. In this embodiment, the engine has the crankshaft oriented long in the width direction of the vehicle body, with the exhaust side facing the front of the vehicle body, and is therefore placed in the engine room at the front of the vehicle body in a horizontally mounted, front-exhaust state.

(1) Basic structure As shown in Figures 1 and 4(A), the engine comprises a cylinder block 1, a cylinder head 2 fixed to the upper surface of the cylinder block 1, and a head cover 3 fixed to the upper surface of the cylinder head 2. As shown in Figure 2, three exhaust ports 4 are formed side by side in the crankshaft direction on the exhaust side of the cylinder head 2, and a flat exhaust manifold mounting surface 5 that surrounds the three exhaust ports 4 is formed on the exhaust side and extends in the front-to-rear direction. In Figure 3(B), the exhaust manifold mounting surface 5 is shown with parallel diagonal lines to clarify the range. The parallel diagonal lines in Figure 2 also indicate flat surfaces.

The 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 from the side by a heat shield (insulator) 8.

As can be seen from Fig. 1, the exhaust manifold 7 has a flange plate 9 that overlaps the gasket 6 and three branch pipes 10 joined to it, and the three branch pipes 10 are gathered into one, and an upper cone part of a catalyst case 12 is joined to a collecting part 11. As can be seen from Fig. 4(A), the hollow part consisting of the branch pipes 10 and collecting part 11 is made by overlapping two plates, one on the front and one on the back, and flange-shaped edge pieces 13 formed on the two plates are fixed by welding.

The upper cone of the catalyst case 12 is provided with a boss 14 for mounting an O2 sensor. As can be seen from FIG. 4(A), the base 15 provided in the assembly section 11 of the exhaust manifold 7 is for mounting the heat shield 8.

As can be seen from Figures 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 top and two at the bottom. Therefore, on the exhaust side of the cylinder head 2, five bosses 17 that are flush with the exhaust manifold mounting surface 5 are formed in a state that they protrude outward above and below, and tapped holes 18 are formed in each boss 17.

In Fig. 1, the bolts 16 are simplified and shown as hexagonal bolts, but in reality, as shown in Fig. 4(A), stud bolts are used for the bolts 16, and the exhaust manifold 7 is fixed with nuts 16a screwed onto the stud bolts. As shown in Fig. 1, inclined bracket pieces 19 are fixed by welding to the upper and 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 three points, two at the top and one at the bottom. The heat shield plate 8 is fixed with stud bolts 20 and nuts 21 shown in Fig. 1.

2 and 4(A), upper and lower water jackets 22, 23 are formed inside the cylinder head 2 in the area between adjacent exhaust ports 4, and at the upper water jacket 22, a valley-shaped recess 24 is formed in the exhaust side of the cylinder head 2 as if carved inward, and the lower end 24a of the recess 24 extends to a position slightly higher than the upper-lower midpoint of the exhaust port 4. For this reason, the recess 24 is formed in a state that extends downward from the upper surface of the exhaust manifold mounting surface 5.

On the other hand, as shown in FIG. 3(A), the gasket 6 is formed so as to cover the entire exhaust manifold mounting surface 5, and the flange plate 9 of the exhaust manifold 7 has almost the same shape as the gasket 6. Therefore, the recess 24 is blocked by the gasket 6, and a pocket portion 25 that opens upward is formed.

For this reason, there is a risk that rainwater may get into the pocket portion 25 when driving in the rain, that water splashed up by the wheels may get into the pocket portion 25 when driving on a flooded road, or that cleaning water may get into the pocket portion 25 when using a high-pressure cleaner. This may cause corrosion of the cylinder head 2, gasket 6, and flange plate 9 over a long period of use.

In this embodiment, first, an opening (through hole) 26 is opened in the gasket 6 at a portion facing the lower end 24a of the recess 24 of the cylinder head 2, while for the flange plate 9 of the exhaust manifold 7, the overlapping surface 27 that overlaps with the gasket 6 is separated for each exhaust port 4 periphery, and the portion between adjacent overlapping surfaces 27 is made into an escape surface 28 that is offset in a direction away from the gasket 6, and a gap 29 that is open above and below and communicates with the opening 26 is formed between the gasket 6 and the escape surface 28.

As can be seen from Figures 3 and 4(B), the flange plate 9 has an outward reinforcing rib 30 formed on its outer periphery. The flange plate 9 is formed by bending and protruding a single sheet of material, and the overlapping surface 27 is formed by protruding (bulging) the sheet of material in the opposite direction to the reinforcing rib 30.

Therefore, the relief surface 28 of the flange plate 9 remains as a blank 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 formed in the outward protruding portion 31. Naturally, the gasket 6 also has a bolt insertion hole 32. Naturally, the gasket 6 and the flange plate 9 of the exhaust manifold 7 also have a through hole 4a that communicates with the exhaust port 4.

As described above, the lower end of the pocket portion 25 is connected to the opening 26 and gap 29 of the gasket 6, so even if water gets into the pocket portion 25, the water does not accumulate in the pocket portion 25 but flows downward to the exhaust manifold 7. This prevents corrosion of the cylinder head 2, gasket 6, and exhaust manifold 7.

In the embodiment, the relief surface 28 spreads in the outer circumferential direction of the flange plate 9, which is due to the fact that each overlapping surface 27 is formed to have as equal a width as possible, thereby making the surface pressure of each overlapping surface 27 uniform after fastening. Therefore, although the gap 29 is open in both the upper and lower directions, if it is also open upward, an air vent effect is produced, so that the left-right width of the gap 29 can be made as small as possible while improving water drainage. In addition, if each overlapping surface 27 is independent for each exhaust port 4, there is also the advantage that machining errors in the flange plate 9 can be absorbed and the adhesion (sealing) to the exhaust manifold mounting surface 5 can be improved.

The overlapping surfaces 27 protrude from the relief surfaces 28, and in this embodiment, the rigidity of each overlapping surface 27 is significantly increased due to the rib effect, further improving the sealing performance between the gasket 6 and the exhaust port 4.

Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, the engines to which the invention is applied are not limited to three cylinders, and the invention can be widely applied to multi-cylinder engines with two or four or more cylinders. Furthermore, the opening does not have to be a small circular hole, and it is also possible to form it in the form of a cut groove that opens upward in a shape similar to the recess 24, or to form a hole of an appropriate size that is not a small hole.

The present invention can be embodied in an engine, and therefore has industrial applicability.

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 Tapped hole 22, 23 Water jacket 24 Recess 24a Lower end 25 Pocket portion 26 Opening 27 Overlap surface 28 Relief surface 29 Gap (flow passage)
32 Bolt insertion hole

Claims (2)

a cylinder head having an exhaust manifold mounting surface formed on an exhaust side thereof, and an exhaust manifold having a flange plate fixed to the exhaust manifold mounting surface via a gasket,
an engine in which a valley-shaped recess that opens upward is formed in the exhaust manifold mounting surface, and an upwardly opening pocket portion is formed by closing the recess with the gasket,
an opening is formed in the gasket, the opening communicating with at least a lower end of the pocket portion, and a gap communicating with the opening and opening at least downward is formed between a flange plate of the exhaust manifold and the gasket,
The gap is formed by displacing a portion of a flange plate of the exhaust manifold in a direction away from the gasket.
engine. The pocket portion is located between adjacent exhaust ports, and a lower end of the pocket portion and the opening are located below an upper end of the exhaust manifold mounting surface.
2. An engine as claimed in claim 1.

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