JPS6121549Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a combustion chamber structure.

In the combustion chamber structure of a direct injection diesel engine that has a cavity formed at the top of the piston, this invention rotates the polygonal plane parallel to the top of the piston in the same direction as the swirl while the piston moves in a direction perpendicular to the top of the piston. The main feature of this combustion chamber is a combustion chamber structure that is characterized by having a cavity that is twisted inside, and one embodiment thereof will be described in detail below with reference to FIGS. 1 to 5.

Reference numeral 2 indicates a combustion chamber of a direct injection diesel engine, which is formed by a cylinder head 4, a cylinder block 6, and a piston 8.

A substantially rectangular plane 12 parallel to the piston top surface 10 is attached to the top of the piston 8 in a direction perpendicular to the piston top surface 10 while being rotated in the same rotational direction as a swirl (arrow A) formed by a known method. Cavity 14 screwed into piston 8
is formed.

The structure 16 corresponding to the space forming the cavity 14 will be further explained in accordance with FIGS. It is continuous in the height h direction while rotating at an even pitch, that is, all cross sections parallel to the upper surface 18 or the lower surface 20 have the same shape as the upper surface 18 or the lower surface 20. In the illustrated case, where the angle α formed by the upper surface 18 and the lower surface 20 and the height are h, the pitch p is p=2π/α·h. α is preferably π/2 or less.

The structure 16 is further provided with an auxiliary body 22 below the lower surface 20 to give roundness to the overall shape. Reference numeral 24 denotes a fuel injection nozzle fixed to the cylinder head 4, and four injection holes 26, 26, . Preferably, it is set in the range of angle α from the corner vicinity 28 of the plane 12 to the downstream side in the swirl direction.

The operation of the combustion chamber 2 with the above configuration will be explained below.

A swirl (arrow A) is generated in the cavity 14 by a well-known means during the suction stroke of the piston 8, and during the compression stroke, air between the piston top surface 10 and the cylinder head 4 flows into the cavity 14 as a squish. to strengthen the swirl.

When fuel is injected into the cavity 14,
Since the cavity 14 is formed into a screw shape, the fuel that collides with the peripheral wall is reflected and diffused in the screw direction, that is, it flows along the flow of the swirl in a direction that strengthens the swirl, and flows into the cavity 14.
It is introduced toward the bottom wall.

Therefore, near the compression top dead center, fuel is prevented from jumping into the space between the piston top surface 10 and the cylinder head 4, and generation of white smoke due to cooling of the fuel spray in this space is prevented. or,
Since the injected fuel is reflected at a high flow velocity in the screwing direction, the fuel and air are mixed well, combustion can be performed rapidly, and the air utilization rate is improved. Therefore, according to this embodiment, the injected fuel is efficiently mixed with air in the cavity 14 and combusted, so that generation of white smoke is effectively prevented, and combustion is improved, resulting in an increase in output fuel efficiency. be effective.

Further, the cavity 14 is extremely easily formed by a core having the shape of the structure 16 when the piston 8 is cast, and the core can be easily removed by twisting after casting, so that it is extremely easy to work. It has a certain effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of the present invention;
2 is an explanatory cross-sectional view of FIG. 1, FIG. 3 is a schematic explanatory view of the structure forming the cavity, FIG. 4 is an explanatory view of FIG.
It is a cross-sectional explanatory view. 2... Combustion chamber, 8... Piston, 14... Cavity, 16... Structure.

Claims (1)

[Scope of utility model registration request] In the combustion chamber structure of a direct injection diesel engine that has a cavity formed at the top of the piston, a polygonal plane parallel to the top of the piston is rotated in the same direction as the swirl and twisted inside the piston in a direction perpendicular to the top of the piston. The combustion chamber structure is characterized by a cavity with a deep shape.