JPS622265Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a swirl chamber type diesel engine, and more particularly to an improvement of a combustion chamber that improves combustion by providing a plurality of nozzles that communicate the swirl chamber and the main chamber.

The swirl chamber type is known as a type of combustion chamber suitable for high-speed diesel engines, but in order to further improve its combustion properties, a combustion chamber with multiple nozzles communicating between the swirl chamber and the main chamber has been proposed. (For example, Japanese Patent Application Laid-Open No. 51-105509).

To explain this with reference to FIG. 1, the vortex chamber 1 is formed in a substantially spherical shape between an engine cylinder head 2 and a mouthpiece 3 fitted from the bottom surface thereof, and has a main nozzle 4 and a relatively small diameter auxiliary nozzle 5. It communicates with the main room 6 via.

The main injection port 4 has an opening 4A on the swirl chamber 1 side opening in the tangential direction of the spherical swirl chamber 1, and an opening 4B on the main chamber 6 side opening slightly toward the center of the cylinder. The gas jet from 1 is ejected toward the center of the main chamber 6. On the other hand, the small-diameter sub-nozzle 5 opens along the injection direction of the fuel injection valve 7 facing the swirl chamber 1, so that a part of the injected fuel flows out into the main chamber 6 during the ignition delay. It is set as.

According to such a combustion chamber, not only the vortex chamber 1 but also the main chamber 6 in which gas flows gently through the sub-nozzle 5
Since fuel is supplied to both chambers and combustion proceeds in both chambers, the maximum combustion temperature is suppressed compared to when the entire amount of injected fuel is supplied only to swirl chamber 1 and combusted, resulting in the generation of NOx, which is a harmful substance. It is known that the amount decreases.

However, on the other hand, the fuel flowing out into the main chamber 6 through the sub-nozzle 5 is combusted while being exposed to the gas jet with low oxygen concentration from the main nozzle 4. Another problem is that in the load range, air is not sufficiently utilized in the main chamber 6 and a large amount of smoke is likely to be generated.

The present invention focuses on these problems and aims to solve the above conventional problems by heating the sub-nozzle with an electric heating element to promote vaporization of the fuel flowing into the main chamber.

The present invention will be explained below based on the embodiment shown in FIG. Note that portions corresponding to those in FIG. 1 are designated by the same reference numerals.

In the present invention, the inner wall surface 5A of the sub-nozzle 5 is formed of an electric heating element 8 as shown in the drawing. In this embodiment, the electric heating element 8 is formed by holding a coiled nichrome wire 8A with an insulator 8B such as ceramic.

The electric heating element 8 (nichrome wire 8A) is energized under predetermined operating conditions to heat the sub-nozzle 5, but in this embodiment, the load condition is detected by the control lever angle of the fuel injection pump (not shown). A load sensor 10 and a control circuit 12 that switches on/off between the electric heating element 8 and the battery 11 based on a signal from the load sensor 10 are provided, and the electric heating element 8 is switched on and off only when the engine is under a certain high load state. It is designed to be energized. Of course, the power may be turned on all the time during operation.

When the ambient temperature or the temperature of the inner wall surface 5A of the sub-nozzle 5 is increased in this way, the fuel from the fuel injection valve 7 is heated when passing through the high-temperature sub-nozzle 5, becomes high temperature, and partially becomes gas. Main room 6
gushes out. Therefore, mixing of fuel and air in the main chamber 6 is promoted, and combustion becomes active. As a result, the amount of smoke generated is reduced.

As described above, according to the present invention, it is possible to improve the combustion of a swirl chamber type diesel engine provided with a sub-nozzle, and to suppress the occurrence of smoke, which is a problem particularly in a high-load operating range.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional example, and FIG. 2 is a longitudinal sectional view of an embodiment of the present invention. 1... Vortex chamber, 2... Cylinder head, 4...
Main nozzle, 5... Sub-nozzle, 5A... Inner wall surface of sub-nozzle, 6... Main chamber, 7... Fuel injection valve, 8... Electric heating element.

Claims (1)

[Scope of utility model registration request] In a diesel engine, a swirl chamber with a fuel injection valve facing the engine cylinder head is provided, and the swirl chamber and the main chamber are communicated through a sub-nozzle opening in the injection direction of the fuel injection valve in addition to the main nozzle. The inner wall surface of the sub-nozzle is formed of an electric heating element, and a control circuit is provided to energize the electric heating element in predetermined operating conditions including relatively high load conditions, and the fuel is supplied from the sub-nozzle to the main chamber. A whirlpool chamber type diesel engine characterized by heating.