JP7626084B2 - Internal combustion engine - Google Patents

Description

This disclosure relates to an internal combustion engine.

Conventionally, internal combustion engines are known that have a chamber plate disposed between the piston and the cylinder head and protruding toward the inside of the cylinder (see, for example, the fuel impingement member in Patent Document 1).

JP 10-227217 A

Patent document 1 discloses an internal combustion engine in which a combustion chamber is formed between a cylinder head and a protrusion on a chamber plate. For this reason, the internal combustion engine of Patent document 1 causes fuel to collide with the chamber plate and diffuse. In an internal combustion engine with this structure, it is difficult to raise the piston top surface toward the cylinder head because it is obstructed by the chamber plate. This makes it difficult to change the compression ratio. In order to be able to change the compression ratio, it is preferable to diffuse the fuel using the piston top surface in addition to the protrusion.

The present disclosure aims to provide an internal combustion engine that can smoothly guide fuel from the piston top surface to the protrusion.

The internal combustion engine of the present disclosure is an internal combustion engine having a cylinder block having a cylinder, a cylinder head, a piston that slides in the cylinder, and a fuel injection valve that is disposed in the cylinder and injects fuel into the cylinder, and is equipped with a step portion formed around a top surface of the piston and having a lower step surface that slopes down from the top surface toward the opposite side of the cylinder head, a protrusion that is disposed on the cylinder head side of the lower step surface of the step portion at the top dead center of the piston and protrudes toward the inside of the cylinder, and an inclined portion that is located closer to the center of the piston than the step portion, is disposed on the top surface of the piston , and inclines from the inside to the outside of the cylinder and toward the cylinder head so as to extend toward the protrusion.

In this internal combustion engine, fuel supplied to the cylinder is guided from the top surface of the piston to the protrusion, which disperses the fuel. This makes it easy to change the shape of the top surface of the piston. This also makes it easy to change the compression ratio. As a result, combustion in the internal combustion engine is improved.

This disclosure provides an internal combustion engine that can smoothly guide fuel from the piston top surface to the protrusion.

1 is a cross-sectional view of an internal combustion engine according to an embodiment of the present disclosure. FIG. 4 is a close-up view of a piston and protrusion according to an embodiment of the present disclosure. FIG. 13 is an enlarged view of a piston and a protrusion according to another embodiment.

An embodiment of the present disclosure will be described below with reference to the drawings.

As shown in FIG. 1, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 4, a piston 6, a chamber plate 8, a cylinder head gasket 10, and a fuel injection valve 12.

The cylinder block 2 has a cylinder 21. The cylinder head 4 is fixed above the cylinder block 2 with a cylinder head gasket 10 and a chamber plate 8 sandwiched therebetween. A fuel injection valve 12, an intake valve 41, an exhaust valve 42, and the like are arranged in the cylinder head 4. The internal combustion engine 1 of this embodiment is a diesel engine that injects fuel directly into the cylinder 21. The internal combustion engine 1 of this embodiment will be described using an example in which the cylinders 21 are arranged in the vertical direction.

As shown in FIG. 2, the piston 6 has an inclined portion 61 and a step portion 62. The piston 6 slides inside the cylinder 21. The inclined portion 61 is arranged around the top surface 6a of the cylindrical piston 6. The inclined portion 61 extends toward a protrusion 81 of the chamber plate 8 described later and is inclined toward the cylinder head 4. In other words, the inclined portion 61 extends from the inside to the outside of the cylinder 21 and extends toward the upper part of the internal combustion engine 1. The inclined portion 61 is provided with an R surface 61a that matches the curvature of a curved surface 82 formed on the protrusion 81 of the chamber plate described later.

The step 62 is formed around the top surface 6a and has a lower step surface 62a that slopes down from the top surface 6a toward the opposite side of the cylinder head 4. The step 62 is formed so that the side surface 62b is located closer to the center of the cylinder 21 than the protrusion 8a of the chamber plate.

At the top dead center of the piston 6, the center of the top surface 6a of the piston 6 is located closer to the cylinder head 4 than the lower end of the protrusion 81. Specifically, the top surface 6a of the piston 6 forms a squish 63 that slopes from approximately the center of the cylinder 21 toward the intake side where the intake valve 41 is located, and toward the exhaust side where the exhaust valve 42 is located, toward the opposite side to the cylinder head 4 (downward in this embodiment). The squish 63 forms a ridgeline near the center of the cylinder 21, and is formed at a position where the height of the ridgeline is higher than the lower surface of the chamber plate 8. This increases the compression ratio.

The chamber plate 8 has a protrusion 81 and a curved surface 82. In this embodiment, two protrusions 81 are formed on either side of the curved surface 82, one on the cylinder block 2 side and one on the cylinder head 4 side. The chamber plate 8 is a plate-shaped member made of a metal such as stainless steel.

The protrusion 81 is positioned closer to the cylinder head 4 than the top dead center position of the step 62 of the piston 6. The protrusion 81 protrudes toward the inside of the cylinder 21. The protrusion 81 on the cylinder block 2 side is accommodated in the step 62 of the piston 6. The curved surface 82 curves from the end 81a of the protrusion 81 on the inside of the cylinder 21 toward the outside of the cylinder 21.

A highly insulating cylinder head gasket 10 is placed between the chamber plate 8 and the cylinder block 2. A highly insulating cylinder head gasket 10 is also placed between the chamber plate 8 and the cylinder head 4. The cylinder head gasket 10 is a gasket with low thermal conductivity, such as graphite, mica, a resin-coated metal gasket, or a resin gasket. This sandwiches the chamber plate 8, which maintains a high temperature state. As a result, the cooling loss of the internal combustion engine 1 can be reduced.

As shown in Figures 1 and 2, by providing the inclined portion 61 and the protrusion 81 of the chamber plate 8 in this way, the fuel spray injected from the fuel injection valve 12 (see M in Figure 1) is pushed up toward the cylinder head 4 along the inclined portion 61, and the spray is smoothly guided toward the chamber plate 8. This makes it possible to prevent the spray from being sucked in between the piston 6 and the protrusion 81.

The spray guided to the chamber plate 8 rises along the curved surface 82 toward the cylinder head 4 and diffuses. In this embodiment, the spray is pushed back toward the inside of the cylinder 21 by the protrusion 81 on the cylinder head 4 side, further diffusing the spray. This improves combustion inside the cylinder 21.

Furthermore, because a labyrinth structure is formed by the step 62 of the piston and the protrusion 81 of the chamber plate 8, oil containing fuel adhering to the chamber plate 8 is less likely to fall onto the wall surface 6b of the piston 6. This makes it possible to prevent oil dilution in the internal combustion engine 1.

In addition, by forming a step 62 on the piston 6, the top surface 6a can be brought closer to the cylinder head 4. This reduces the surface area of the combustion chamber at the top dead center of the piston 6, thereby reducing the cooling loss of the internal combustion engine 1. Furthermore, since the protrusion 81 is accommodated in the step 62, it is easy to change the shape of the top surface 6a. Therefore, it is possible to form a squish 63 as in this embodiment and increase the compression ratio.

As described above, the present disclosure provides an internal combustion engine 1 that can smoothly guide fuel from the top surface 6a of the piston 6 to the protrusion 81.

<Other embodiments>
Although the present embodiment has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

(a) In the above embodiment, two protrusions 81 are provided, one on the cylinder block 2 side and one on the cylinder head 4 side, with the curved surface 82 in between, but the present disclosure is not limited to this. As shown in FIG. 3(a), for example, one protrusion 81 may be provided on the cylinder block 2 side.

(b) In the above embodiment, the chamber plate 8 is provided with a curved surface 82, but the curved surface 82 is not necessarily required. For example, as shown in FIG. 3(b), a linearly inclined inclined surface 282 may be used.

(c) In the above embodiment, an example was described in which the curvatures of the curved surface 82 and the R surface 61a were matched, but the present disclosure is not limited to this. As long as the inclined portion 61 and the protrusion 81 are continuous surfaces, the curvatures of the curved surface 82 and the R surface 61a do not necessarily have to match.

1: internal combustion engine, 2: cylinder block, 4: cylinder head, 6: piston, 6a: top surface, 8: chamber plate, 8a: protrusion, 10: cylinder head gasket, 21: cylinder, 61: inclined portion, 62: step portion, 62a: lower surface, 63: squish, 81: protrusion, 81a: end portion, 82: curved surface

Claims (4)

An internal combustion engine comprising: a cylinder block having a cylinder; a cylinder head; a piston that slides in the cylinder; and a fuel injection valve that is disposed in the cylinder and injects fuel into the cylinder ,
a step portion having a lower step surface formed around a periphery of a top surface of the piston and descending from the top surface toward an opposite side to the cylinder head;
a protrusion that is disposed closer to the cylinder head than the lower surface of the step portion at the top dead center of the piston and protrudes toward the inside of the cylinder;
a sloped portion that is located closer to the center of the piston than the step portion, is disposed on the top surface of the piston, and slopes from the inside to the outside of the cylinder and toward the cylinder head so as to extend toward the protrusion;
An internal combustion engine comprising: At the top dead center of the piston, a lower end of the protrusion fits into the step portion, and the cylinder head side end of the inclined portion and an inner end of the cylinder of the protrusion are at the same height.
2. The internal combustion engine of claim 1. The protrusion has a curved surface that curves from an end of the protrusion on the inside of the cylinder toward the outside of the cylinder.
3. An internal combustion engine according to claim 1 or 2. At the top dead center of the piston, the center of the top surface of the piston is located closer to the cylinder head than the lower end of the protrusion.
An internal combustion engine according to any one of claims 1 to 3.