JP3029946B2 - Scavenging chamber structure of diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scavenging device for a two-cycle diesel engine mainly used as a marine engine.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 7 is a schematic view of a scavenging flow in a cross section including a cylinder axis of a two-cycle diesel engine, FIG. 8 is a cross-sectional view perpendicular to the cylinder axis of a scavenging chamber in a conventional two-cycle diesel engine, and FIG. It is sectional drawing which shows the state of the scavenging flow in the said conventional diesel engine.

In FIG. 7, 1 is a cylinder liner, 2 is an exhaust valve, 3 is a piston, 4 is a scavenging flow, and 5 is a scavenging port. In order to give swirling flow to the scavenging air during the scavenging stroke, a plurality of scavenging ports 5 are arranged in the circumferential direction of the cylinder liner 1 and have an appropriate twist angle. In the diesel engine, if the flow rate of the air flowing into the scavenging port 5 is uniform in the circumferential direction, the inflow speed is also uniform in the circumferential direction. As shown in FIG. 7, the swirl axis of the swirl in the cylinder is It is almost equal to the axis of the liner.

In FIG. 8, which is a cross section perpendicular to the axis of the cylinder liner 1, 1 is a cylinder liner, 5 is a scavenging port, 6 is a cylinder jacket, 7 is a scavenging trunk, 10
Is a scavenging chamber, and 8 is an air inlet for connecting the scavenging chamber 10 and the scavenging trunk 7. 8 and 9, the scavenging ports 5 are uniformly arranged in the circumferential direction, and are inclined in one direction as shown in the direction of the scavenging flow 9 flowing into the scavenging chamber 10 from the scavenging trunk. Perforated. 11 is the center of the swirl.

[0005]

However, in the scavenging chamber structure of the conventional diesel engine, only one inflow passage from the scavenging trunk 7 to the scavenging chamber 10 of the cylinder jacket 6 can be arranged. Therefore, as shown by E in FIG. 9, the flow 9 of the scavenging gas flows between the scavenging port 5 facing the inflow direction of the scavenging gas and the scavenging port 5 not facing shown by F in the drawing. The inflow velocity as shown causes imbalance. As a result, the swirl center 1 formed in the cylinder
1 is pressed by scavenging gas having a high inflow velocity flowing from the scavenging port 5 at the E position and is eccentric in the direction of the F position as shown in the figure, so that scavenging efficiency is deteriorated and engine performance is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the problems of the conventional apparatus, remove eccentricity of a swirl center in a cylinder, and smoothly perform an exhaust gas exchange action by scavenging, thereby improving engine performance. To provide a scavenging chamber structure for an engine.

[0007]

The scavenging chamber structure of a diesel engine according to the present invention is characterized in that the scavenging air flowing into each scavenging port 5 near the scavenging air inlet 15 from the scavenging trunk 7 to the scavenging chamber 10 in the cylinder jacket 6 is provided. The control plate 12 for equalizing the inflow speed is set at r = 0.6 with respect to the center of the cylinder liner 1.
~ 1.5 and the control plate area f = 0.4 ~ 1.7.

Here, r: (R / b) dimensionless distance of the control plate from the cylinder center f: (F / S) dimensionless area of the rectifier plate R: absolute distance from the cylinder center to the control plate F: rectifier plate B: Internal diameter of cylinder S: Total passage area of scavenging port

[0009]

Since the control plate 12 is installed near the scavenging air inlet 15 which connects the scavenging trunk 7 and the scavenging chamber 10, scavenging gas flowing from the scavenging trunk 7 into the scavenging chamber 10 is controlled by the control plate 12
Is rectified.

Further, by setting the position and area of the control plate within a predetermined range, it is possible to prevent the flow rate of scavenging air from decreasing and the scavenging air from flowing directly into the scavenging port.

Therefore, as in the prior art, the scavenging air does not flow directly from the scavenging trunk 7 into the scavenging port 5 of the cylinder liner at the position E in FIG. As a result, the eccentricity of the swirl center in the cylinder liner is removed, and the scavenging efficiency and the engine performance of the engine can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the drawing, 1 is a cylinder liner, 3 is a piston, 5 is a scavenging port formed in the lower part of the cylinder liner 1 at equal intervals in the circumferential direction, 6 is a cylinder jacket, and 7 is pressure feed from a supercharger (not shown). The scavenging trunk in which the scavenging air to be stored is stored, and 10 is a scavenging port 5 for each cylinder.
And a scavenging chamber (piston underside chamber) defined for each cylinder.

FIGS. 2A and 2B show a first embodiment of the present invention. In FIG. 2, reference numeral 15 denotes a scavenging air inlet which communicates the scavenging trunk 7 with the scavenging chamber 10 of each cylinder. A control plate 12 for controlling a scavenging flow is provided at the scavenging air inlet 15.

The mounting position and area of the control plate 12 are set as follows. Mounting position of control plate: r (see FIG. 2) r = R / b = 0.6 to 1.5 where r: dimensionless distance of control plate from cylinder center 1C R: distance from cylinder center 1C to control plate Absolute distance (shortest distance) b: Inner diameter of cylinder

Area of control plate: ff = F / S = 0.4 to 1.7 where f: dimensionless area of control plate F: absolute area of control plate S: total passage area of scavenging port 5

The control plate 12 is shown in FIGS.
(B) As shown in the figure, it has a height that covers the entire height of the scavenging port 5 in the projection in the cylinder axis direction.

In the first embodiment shown in FIG. 2, scavenging air introduced into the scavenging trunk 7 from a feeder (not shown) is mainly scavenged from between the upper and lower ends of the control plate 12 and the scavenging air inlet 15. After flowing into the chamber 10, it is diffused in the scavenging chamber 10 along the outer periphery of the cylinder liner 1, and flows into the cylinder from the scavenging port 5 together with the opening of the scavenging port 5.

A description will now be given of the basis for setting the mounting position and area of the control plate 12 and the operation thereof. When the distance from the control plate 12 to the cylinder liner 1 is small, the control plate 12
In such a case, the scavenging air flowing into the scavenging port 5 opposite to the above is suppressed more than necessary, and the inflow speed of the scavenging air decreases. On the other hand, when the distance from the control plate 12 to the cylinder liner 1 is large, it is not possible to suppress scavenging air from directly flowing into the scavenging port 5 facing the control plate 12. Therefore, it is necessary to keep the distance from the control plate 12 to the cylinder liner 1 within a range that does not cause the above-described problem.

FIGS. 5 and 6 show changes in the engine efficiency when the distance from the control plate 12 to the cylinder liner 1 is changed when the first embodiment is applied to an actual diesel engine. In FIG. 5, the distance from control plate 12 to cylinder liner 1 is represented by dimensionless distance r (r = R / b) of control plate 12 from the center of the cylinder. The engine efficiency is represented by the fuel consumption rate of the engine (hereinafter referred to as fuel efficiency).

According to the results of this experiment, the distance r was set to 0.7 to
When it is set to around 0.85, the engine efficiency is most improved. However, according to experimental results in other application examples, the distance r is 0.6 to
It is preferable to install within the range of 1.5.

Next, the area of the control plate 12 will be described.
When the area of the control plate 12 is smaller than the passage area of the scavenging port 5, it is not possible to suppress the scavenging air from flowing directly into the scavenging port 5. Conversely, if the area of the control plate 12 is large, the scavenging that is going to flow into the scavenging port 5 facing the control plate 12 will be suppressed more than necessary, and the inflow speed will decrease. Therefore, it is necessary to set the area of the control plate 12 in a range that does not cause the above-described problem.

FIG. 6 shows a change in engine efficiency when the area of the rectifying plate 12 is changed when this embodiment is applied to an actual diesel engine. 6, the area of the control plate 12 is represented by a dimensionless area f (f = F / S). The engine efficiency is represented by the fuel efficiency of the engine. According to this result, when the area f is around 0.5 to 0.6, the engine efficiency is most improved. However, according to the experimental results in other application examples, the area f is 0.4 to 1.7. It is preferable to set it in the range.

As shown in the above embodiment, in the present invention, since the control plate 12 and its mounting position and area are provided within the above-mentioned range, scavenging is concentrated particularly at the position E in the drawing. Inflow is suppressed, the scavenging flow to each scavenging port 5 is equalized, the center of the swirl is eccentric as in the conventional case, and high scavenging efficiency can be maintained without lowering scavenging efficiency.

FIGS. 3A and 3B show a second embodiment of the present invention. In this embodiment, the control plate 12 disposed at the scavenging air inlet 15 is inclined at an angle θ with respect to the inner surface of the partition wall 6a between the scavenging trunk 7 and the scavenging chamber 10, so that the control plate is further controlled. The rectification effect is improved.

FIG. 4 shows a third embodiment of the present invention. First to first
In the second embodiment, when the direction of the scavenging port 5 of the cylinder liner 1 is viewed from the scavenging trunk 7, the scavenging port 5 is positioned so as to be completely hidden by the control plate 12. Is positioned so that the upper part of it is exposed. In this case, the same operation and effect as those of the first and second embodiments can be obtained.

[0026]

According to the present invention, since the scavenging gas flowing from the scavenging trunk into the scavenging chamber is changed in direction by the control plate, the scavenging air flows directly into the scavenging port. Disappears. In particular, since the opening below the control plate at the scavenging flow inlet opening to the scavenging trunk becomes large, the macro scavenging flow mainly flows from the lower opening of the control plate, and the upward flow flows to the scavenging flow from the scavenging port. As the scavenging air is generated and flows in from each scavenging port, the inflow velocity of the scavenging air is made uniform in the circumferential direction, the center of the swirl in the cylinder substantially coincides with the cylinder axis, and the eccentricity of the swirl is eliminated.

Therefore, the exchange of exhaust gas with fresh air by scavenging is smoothly performed, and improvement in engine performance can be expected. In addition, the blow-through of fresh air is reduced by the throttle function of the control plate, the exhaust gas temperature is increased, and the efficiency of the exhaust turbocharger is also increased.
The overall engine performance is improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a cylinder showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the first embodiment of the present invention, which is perpendicular to the cylinder axis.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a view showing a third embodiment of the present invention as viewed from a scavenging air inlet;

FIG. 5 is a diagram showing the operation of the present invention.

FIG. 6 is a diagram showing the operation of the present invention.

FIG. 7 is a schematic sectional view of a cylinder axis showing a conventional example.

FIG. 8 is an equivalent view of FIG. 2 showing a conventional example.

FIG. 9 is an equivalent diagram of FIG. 2 for explaining the operation of the conventional example.

[Explanation of symbols]

 Reference Signs List 1 cylinder liner 3 piston 5 scavenging port 7 scavenging trunk 10 scavenging chamber 12 control plate 15 scavenging air inlet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-365930 (JP, A) JP-A-4-132857 (JP, A) JP-A-64-56914 (JP, A) JP-A-62- 174534 (JP, A) Japanese Utility Model 4-137222 (JP, U) Japanese Utility Model 4-71737 (JP, U) Japanese Utility Model 63-183323 (JP, U) Japanese Utility Model 60-82523 (JP, U) Japanese Utility Model Showa 58-146013 (JP, U) Japanese Utility Model Showa 62-128114 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02F 1/22 F02B 25/04 F02M 35/10

Claims (1)

(57) [Claims] 1. A two-cycle diesel engine in which residual gas in a cylinder is discharged from an exhaust valve provided in an upper part of a cylinder by scavenging introduced from a number of scavenging ports formed in a lower part of a cylinder liner along a circumferential direction. A control plate is provided near the scavenging air inlet that connects the scavenging chamber of each cylinder facing the scavenging port and the scavenging trunk, so that the inflow speed of scavenging gas flowing into each scavenging port is made uniform in the circumferential direction of the cylinder liner 2. The control plate has a dimensionless position r from the center of the cylinder.
Is set to r = R / b = 0.6 to 1.5, and the dimensionless opening area f is set to f = F / S = 0.4 to 1.7 where R is the control plate from the cylinder center. The scavenging chamber structure of a diesel engine, wherein b is the cylinder inner diameter, F is the absolute area of the control plate, and S is the total passage area of the scavenging port.