JPS6115217Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion chamber shape that improves combustion by increasing air utilization in a diesel engine equipped with a swirl chamber.

In a swirl chamber type diesel engine, the piston is pushed into the swirl chamber during the compression stroke to form a swirl, and fuel is injected here to create a mixed gas with air, increasing the chance of contact between the fuel and air to improve ignitability and combustion. We aim to improve The ignited combustion flame is then pushed out from the vortex chamber through the communication hole, expands into the main chamber, and produces output.

Therefore, the forced vortex flow in the vortex chamber is made effective by supplying new air one after another to the injected fuel and the fuel adhering to the wall of the vortex chamber to improve the mixing of air and fuel. In addition to making the pushing vortex sufficiently strong, it is also desirable to form a small turbulence in the vortex (see JP-A-52-29512 and JP-A-52-29513).

In addition, small turbulence is applied to the flame flow from the vortex chamber to the piston cavity through the communication hole in order to disturb the flame and mix the unburned components and new air. It is better to make it and mix it well.

In view of the above, the present invention provides a combustion chamber in which a plurality of step-like uneven surfaces substantially perpendicular to the flame flow are formed on a part of the inner wall of the piston cavity.

Embodiments of the present invention will be described below based on the drawings.

FIGS. 1A and 1B show an embodiment of the present invention, in which a cylinder head 1 and a mouthpiece 2 press-fitted therein form a swirl chamber 3 and a communicating hole 4. FIG. A main chamber 8 surrounded by the lower surface of the cylinder head 1, the cylinder 6 of the cylinder block 5, and the top surface of the piston 7 communicates with the swirl chamber 3 through the communication hole 4. The communication hole 4 is oriented tangentially to the inner wall of the swirl chamber 3. The inner wall of the cavity 31 formed on the top surface of the piston 7 is formed with a plurality of step-like uneven surfaces 32 substantially perpendicular to the flame injection direction. During the compression stroke of the piston 7, compressed air is forced into the swirl chamber 3 through the communication hole 4,
A vortex A is formed by being guided by the inner wall of the vortex chamber. The fuel injected from the fuel injection valve 14 toward the swirl A ignites within the swirl chamber 3 . The combustion flame is ejected from the communication hole 4 into the cavity 31 of the piston 7, but a small turbulence D of the flame is generated by the uneven surface 32 of the cavity 31, which causes the surrounding air to be drawn in and cause the flame to explode. It is mixed with unburned components and burned. Therefore, the amount of unburned components produced is reduced, and the HC emissions of the swirl chamber type diesel engine can be reduced, resulting in improved fuel efficiency and increased output. The planar shape of the piston cavity 31 is circular as in this embodiment, and its inner wall is formed with a step-like uneven surface 32, and a fan-shaped cavity 33 is formed as shown in FIGS. 2A and B. It may also be a step-like uneven surface 34 that is parallel to orthogonal to the flame injection direction C. Of course, other shapes such as a cloverleaf cavity or the like may be used to spread the sprayed flame throughout the main chamber as much as possible.

Incidentally, the uneven surface that creates small disturbances in the flow may be provided in the vortex chamber or the communication hole, in which case the size of the uneven surface in each part is left to the discretion of the design.

As described above, according to the present invention, the inner wall of the piston cavity is provided with a large number of concave and convex portions that are substantially orthogonal to the gas flow to disrupt the gas flow. Therefore, good mixing of unburned fuel and air is achieved, improving air utilization and improving combustion.

[Brief explanation of the drawing]

FIG. 1A is a longitudinal cross-sectional view of a combustion chamber according to one embodiment of the present invention, FIG. 1B is a plan view of FIG. 1A, and FIGS. 2A and B show other embodiments of the present invention. FIG. 2 is a vertical sectional view and a plan view. 7... Piston, 8... Main chamber, 14... Fuel injection valve, 32, 34... Uneven surface, 31, 33... Cavity, A... Vortex, C... Flame flow, D... Small turbulence.

Claims (1)

[Scope of utility model registration request] A diesel engine with a swirl chamber, characterized in that a plurality of step-like uneven surfaces substantially orthogonal to the flame injection direction are formed on a part of the inner wall of the cavity formed on the top wall of the piston. .