JPS60261920A - Vortex chamber type diesel engine - Google Patents

Abstract

PURPOSE:To prevent atomized fuel from adhering to the inner wall of a counter injection port and to reform fuel to reduce the amount of generated smoke, by forming the cross-section of the counter injection port in a substantially circular shape, and by setting a specific relationship between the cross-sectional area and length of the counter injection port. CONSTITUTION:Atomized fuel injected from a fuel injection valve 7 is led by a vortex stream and impinges upon a glow plug 11 so that it drops in a substantially vertical direction along the direction of the vortex stream. However due to a delay in ignition it passes through a counter injection port 10 in an atomized condition. In this arrangement, the cross-sectioned shape of the counter injection port 10 is formed to be substantially circular to facilitate the passage of atomized fuel therethrough, and the relationship between the cross-sectional area S and length L of the counter injection port is set such as, S/L>0.5 to reduce the amount of generated smoke. That is, the relationship of S/L>0.5 allows the passage length to be short with respect to the passage cross-sectional area so that fuel is directly fed into a main chamber without adhering to the inner wall 10A of the counter injection port. Therefore, fuel adhered to the inner wall 10A of the counter injection port 10 is prevented from being burnt with some delay so that the counter injection port 10 may attain its inherent purpose, and therefore, combustion may be carried out within the main chamber to reduce the amount of generated smoke.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an improvement of a swirl chamber type diesel engine, and more specifically, an improvement of a swirl chamber type diesel engine having a plurality of nozzles communicating between a swirl chamber and a main chamber. Regarding.

(Prior art) The swirl chamber type is known as a combustion chamber type suitable for high-speed diesel engines, but in order to further improve its combustion properties, multiple nozzles are provided to communicate the swirl chamber and the main chamber. (For example, Japanese Patent Application Laid-Open No. 57-1721
(See No. 23).

To explain this with reference to FIG. 5, the vortex chamber 1 is formed between the engine cylinder Rad 2 and the 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 room 6.

The main nozzle 4 has an opening on the swirl chamber 1 side opening in the tangential direction of the swirl chamber 1, and an opening on the main chamber 6 side opening slightly toward the center of the cylinder. The gas jet 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 into the main chamber 6 during the ignition delay. I'm here.

According to such a combustion chamber, fuel is supplied not only to the swirl chamber 1 but also to the main chamber 6 where the gas flow is moderate through the sub-nozzle 5, and combustion progresses in both, so that the total amount of injected fuel is It is known that the maximum combustion temperature is suppressed compared to the case where fuel is supplied to only one swirl chamber and combusted, and as a result, the amount of NOx, which is a harmful substance, generated is reduced.

(Problem to be solved by the invention) By the way, the appropriate amount of fuel to be supplied to the main chamber 1 may be small;
Since the amount of fuel injected through the sub-nozzle 5 is determined by the cross-sectional area of the sub-nozzle 5, the cross-sectional area of the sub-nozzle cannot be set so large.

For this reason, in the sub-nozzle 5 having a narrow passage cross-sectional area, the sprayed fuel tends to adhere to the inner wall 5A, especially in a high load region where the fuel injection amount increases, and the passage length is smaller than the passage cross-sectional area. If it is long, it will encourage the tendency to stick.

If the fuel adheres to the inner wall 5A in this way, it is conceivable that the combustion condition will worsen and the amount of smoke generated will increase because there is not enough oxygen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diesel engine in which a sub-nozzle is shaped so that fuel can easily pass through the sub-nozzle to prevent fuel from adhering to the inner wall of the sub-nozzle.

(Means for Solving the Problems) The present invention provides a swirl chamber facing the fuel injection valve in the engine shilling head, and combines the swirl chamber and the main chamber with one main injection valve and the fuel injection valve. The present invention is based on a swirl chamber type diesel engine that communicates through a sub-nozzle opening in the injection direction.

In the present invention, the cross section of the sub-nozzle is formed into a generally circular shape,
The ratio S/L of the cross-sectional area S of one nozzle to the length L of the sub-nozzle is set to be greater than 0.5.

(Function) With this setting, even if the passage cross-sectional area is small, the passage length becomes short, making it easier for the sprayed fuel to pass through the auxiliary nozzle, and even in a high load range, the sprayed fuel adheres to the inner wall of the nozzle. It will be supplied to the main room without doing anything.

(Example) Figure tjS1 is a longitudinal sectional view showing a swirl chamber according to an example of the present invention.

The ``0'' embodiment is applied to a device in which the vortex chamber is formed into a flat cylindrical shape in order to increase the directionality of the vortex chamber υ.

That is, the swirl chamber 1 is formed by a right cylindrical surface IA in which the main jet i]4 is opened, and two side planes (not shown) that are orthogonal to the central axis of this right cylindrical surface IA and are substantially parallel to each other. ing.

The main nozzle 4 is formed tangentially to the swirl chamber 1 , whereas the small-diameter auxiliary nozzle 10 is formed to substantially coincide with the central injection axis of the fuel injection valve 7 facing the swirl chamber 1 .

20 The cross section of the sub-nozzle 10 is formed into a circular shape with a small ratio of circumferential length to area.

Further, the ratio S/L of the sub-nozzle cross-sectional area S to the sub-nozzle length L is set to J:' such that it is larger than 0.5.

In addition, 2 is a sill head, 3 is a mouthpiece, 1°A is an inner wall of a sub-nozzle, and 11 is a glow plug.

To explain the effect of the above configuration, the forced flow that flows into the swirl chamber 1 through the main nozzle 4 during the compression process flows into the right cylindrical surface IA from the tangential direction to form a swirl, but the vortex flow is Since it is guided by a lateral plane substantially perpendicular to the center of rotation and maintains strong directionality, a sufficient vortex state is maintained even under the influence of counterflow from the sub-nozzle 1o. That is, the atomized fuel injected from the fuel injection valve 7 hits the glow plug 10 due to this vortex and falls generally vertically along the direction of the vortex, but because of the ignition delay, it passes through the sub-nozzle 10 in a spray state. do.

In this case, the ease with which the sprayed fuel passes through the sub-nozzle 10 is related to the shape of the sub-nozzle 10 and S/L1.

For example, the cross-sectional shape that is easy to pass through is circular, and J, ta,
Regarding S/I-, exhaust characteristics when changing S/L are shown in FIGS. 3 and 4.

Note that these figures were created based on actual measurements when S was kept constant and L was varied in FIG. 2.

From Figure 3, in the high load range, the amount of smoke generated is S/
As I increases, it decreases, so it can be seen that by making S/L larger than 0.5, the amount of smoke generated can be reduced regardless of the high load range.

Note that the formation of the sub-nozzle 1o does not affect the amount of NOx, which is another exhaust component (115).
(See Figure 4). Further, the set values of S/T- may be set according to exhaust regulation values.

That is, when S/L is larger than 0.5, the passage length becomes shorter than the passage cross-sectional area, and the atomized fuel reaches the inner wall 10 of the sub-nozzle.
It is supplied to the main room without adhering to A.

Therefore, the fuel attached to the inner wall 10A of the auxiliary nozzle 10A does not become an afterthought, and the 1i (i nozzle 10 plays the final role and combustion takes place in the main chamber.
It can reduce smoke.

(Effects of the Invention) The present invention has a sub-nozzle cross section approximately circular in shape, and has a relationship between the sub-nozzle cross-sectional area S and the sub-nozzle length I such that S/L>0.5. By setting this, it is possible to prevent the sprayed fuel from landing on the inner wall of the sub-nozzle, thereby achieving a reduction in the amount of smoke generated due to improved combustion.

[Brief explanation of the drawing]

#S1 is a vertical sectional view of the combustion chamber of one embodiment of the present invention,
The figure is a longitudinal sectional view of a plurality of nozzle ports. FIGS. 3 and 4 are smoke and NOx exhaust characteristic diagrams, respectively. FIG. 5 is a longitudinal sectional view of a conventional combustion chamber. 1... Vortex chamber, 2... Cylinder head, 3... Mouthpiece, 4... Main nozzle port, 5.10... Sub-nozzle port, 5A, I
OA...Sub-injection 11 inner wall, 7...Fuel injection valve. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Restoration Political Council

Claims (1)

[Claims] A vortex chamber in which a vortex chamber facing a fuel injection valve is provided in the ennon cylinder head, and the vortex chamber and the main chamber are communicated via a sub-nozzle opening in the injection direction of the fuel injection valve in addition to the main nozzle. In the type diesel engine, the cross-section of the sub-nozzle is approximately circular, and rIRvk is set between the cross-sectional area S of the sub-nozzle and the length L of the sub-nozzle such that S/L>0.5. Swirl chamber diesel engine.