JPH06248953A - Piston for reciprocating internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a piston for an reciprocating internal combustion engine, having high thermal efficiency and low pollution, by providing a simple air passage in a piston in a direct injection type diesel engine to promote sufficient mixing between air and fuel spray. CONSTITUTION:In a direct injection type diesel engine having a cavity (combustion chamber) 9 on the top part of a piston 8, an air passage 10, communicating between the piston top surface and the wall surface of the combustion chamber 9, is provided coaxially to the injection direction of fuel spray 7.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to reciprocating internal combustion engines.

[0002]

2. Description of the Related Art A conventional piston 08 is shown in FIG.
Is an example of a reciprocating internal combustion engine in which the gas in the cylinder 06 is compressed by and the fuel is directly injected from the fuel injection valve 01 into the combustion chamber (cavity) 09 of the piston. 0 in the figure
1 is a fuel injection valve, 02 is an air supply pipe, 03 is an air supply valve, 04 is an exhaust pipe, 05 is an exhaust valve, 06 is a cylinder, 07 is fuel spray, 08 is a piston, and 09 is a combustion chamber.

Next, the operation of the conventional example will be described.
When the air supply valve 02 is opened, the piston 08 descends and sucks air into the cylinder 06. Next, when the air supply valve 03 is closed and the piston 08 rises, the air in the cylinder 06 is adiabatically compressed and becomes high temperature and high pressure. When the fuel spray 07 is injected into the combustion chamber from the fuel injection valve 01 when the piston 08 is near the top dead center, the fuel and the compressed air of high temperature and high pressure are mixed and self-ignited to start combustion.

[0004]

However, the above conventional example has the following problems. That is, since the combustion mode of the direct injection type diesel engine is diffusion combustion in which fuel and air proceed while mixing with each other, intake of air into the combustion chamber is very important for complete combustion. Also from the viewpoint of low pollution, it is essential to increase the amount of air introduced into the fuel spray in order to promote the oxidation of soot. On the other hand, in the above-mentioned conventional example, since the momentum associated with the fuel injection has a great influence on the mixing of fuel and air, a means for increasing the injection pressure is taken, but there is a limit to the increase in the pressure and an increase in cost. Is also connected.

An object of the present invention is to solve the problems of the conventional device, to promote the mixing of fuel and air without making a great change to the engine itself, and to improve the engine performance. In providing the piston.

[0006]

A piston for a reciprocating internal combustion engine of the present invention is a direct injection type reciprocating internal combustion engine in which a piston 8 for compressing gas in a cylinder communicates a piston top surface with a wall surface of a combustion chamber 9. It is characterized in that the passage 10 is provided coaxially with the injection direction of the fuel spray 7.

[0007]

The piston 8 ejects the air in the cylinder through the air passage 10 into the combustion chamber 9 during the compression stroke. At this time, since the discharge direction of the air passage 10 to the combustion chamber is provided coaxially with the injection direction of the fuel spray 7, the air and the fuel collide with each other so as to face each other, and have a function of promoting the mixing of the fuel and the air. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a fuel injection valve, 2 is an air supply pipe,
3 is an air supply valve, 4 is an exhaust pipe, 5 is an exhaust valve, 6 is a cylinder,
7 is a fuel spray, 8 is a piston, 9 is a combustion chamber, and 10 is an air passage. The piston 8 of the direct injection diesel engine according to the present invention is provided with an air passage 10 that communicates the piston top surface with the wall surface of the combustion chamber 9, and further, the center of the combustion chamber outlet side is the injection of the fuel spray 7. Its feature is that it is opened in the same direction as the direction.

Next, the operation of the above embodiment will be described.
When the air supply valve 3 opens first and the piston 8 descends, air is sucked into the cylinder. Next, the air supply valve 3 is closed and the piston 8
As a result, the compression stroke occurs, and the air in the cylinder is adiabatically compressed to high temperature and high pressure. When the piston 8 approaches the top dead center, fuel is injected from the fuel injection valve 1. At the same time, as the piston 8 rises, compressed air is ejected into the combustion chamber 9 through the air passage 10. Since the outlet of the air passage 10 on the combustion chamber side is provided coaxially with the fuel injection direction, the air flow collides with the tip of the fuel spray in such a manner that the air flow opposes and mixes well with the air. A heat-efficient and low-pollution engine can be realized.

[0010]

Since the present invention is configured as described above, in a direct injection diesel engine in which the piston top surface forms a combustion chamber cavity, the high temperature high pressure air in the cylinder during the compression stroke causes the air passage 10 of the piston to flow. Through the combustion chamber 9
Since it flows into the inside and collides against the fuel spray, the mixture of fuel and air is promoted, and high efficiency and low pollution combustion can be achieved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an internal combustion engine including a piston according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of part II in FIG.

FIG. 3 is a prior art example of FIG. 1.

[Explanation of symbols]

 7 fuel spray, 8 piston, 9 combustion chamber, 10 air passage.

Claims (1)

[Claims] 1. In a direct injection reciprocating internal combustion engine, a fuel spray (7) is provided in an air passage (10) which connects a piston top surface and a wall surface of a combustion chamber (9) to a piston (8) which compresses gas in a cylinder. ) The piston for a reciprocating internal combustion engine, which is provided coaxially with the injection direction.