JPS61232321A - Scavenged gas controller for uniflow scavenging type internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve combustion efficiency over a wide range by securing the proper scavenging area and the strength of swirl in accordance with the engine operation condition by installing a swirl controller for partially opening and closing a scavenging hole from the lower part onto the outer peripheral part of a cylinder in rotatable and slidable ways. CONSTITUTION:A scavenging hole 41 is directed in the eccentric direction with respect to the axis center of a cylinder 4 so that a proper swirl is generated in the flow of scavenged gas. The inflow angles thetaa and thetab in the upper and lower parts of the scavenging hole 41 are set in the following relation: thetaa>thetab. In the above, a variable swirl apparatus 7 is installed, and a control part 71 for partially covering and opening and closing the scavenging hole 41 is installed. The driving part 72 of the above-described apparatus 7 is driven by a motor 74 through a hook 73. When the variable swirl apparatus 7 is shifted, for example, leftward, and the lower part area of the scavenging hole 41 is largely covered by the control part 71, the area of the part where the inflow angle thetaa of the upper part is large increases, and the scavenged gas in a strong swirl can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scavenging control device for a two-stroke uniflow scavenging diesel engine.

[Conventional technology]

FIG. 3 shows the general structure of the upper part of the cylinder, etc. of a conventional two-stroke uniflow scavenging diesel engine.

In FIG. 3, 1 is a cylinder cover, 2 is an exhaust valve, 3 is a fuel injection valve, 4 is a cylinder liner, 41 is a scavenging hole, 5 is a piston, and 6 is a scavenging chamber. .

Next, the operation of the conventional example will be explained.

When the piston 5 rises, the gas in the combustion chamber surrounded by the cylinder cover 1, exhaust valve, cylinder liner 4, and piston 5 is compressed and heated to a high temperature. Fuel is injected from the fuel injection valve 3, ignites, and burns. When the pressure in the room increases,
The piston 5 is pushed down, transmits its work to a crankshaft (not shown), and takes it out as power to the outside.

When the piston 5 descends, the exhaust valve first opens, and the combustion gas in the combustion chamber flows out to an exhaust pipe (not shown).The pressure in the combustion chamber drops, and when the pressure in the combustion chamber 6 reaches the same level as that in the scavenging chamber 6, the piston 5 opens the scavenging hole 41 provided at the bottom of the liner. When the scavenging hole 41 opens, fresh air flows from the scavenging chamber 6 to the scavenging hole 4.
1 and flows into the cylinder 4, the combustion gas is pushed out to the exhaust hole and scavenged. When the piston 5 passes through the bottom dead center and rises again to close the scavenging hole 41, the inflow of fresh air and the scavenging end.

FIG. 4 shows an example of this scavenging hole 41, and the scavenging hole 41 is oriented eccentrically with respect to the axis of the cylinder 4 so as to give an appropriate swirl to the flow of scavenging air.

In the example shown in the figure, the inflow angles at the upper and lower parts of the scavenging hole 41 are different, such as θ, T and 08B (θ, T upper part> θ
88 lower part).

This causes the scavenging hole 4 to be moved by the piston 5 in the cylinder.
The strength of the swirling flow is changed depending on whether the number of openings is only in the upper part or in the case where all the holes are opened, thereby improving the scavenging efficiency and the combustion efficiency during combustion.

[Problem that the invention seeks to solve]

Although the above-described structure is intended to improve scavenging efficiency and combustion efficiency, the area and inflow angle of the scavenging holes are constant regardless of the rotational speed and load of the engine.

For this reason, even in areas where the air flow rate is low during partial loads, the scavenging holes are wide open and the strength of the swirl remains unchanged.

Therefore, the scavenging efficiency is insufficient, and moreover, the air utilization rate for combustion does not increase and combustion often deteriorates.

In other words, in order to improve the efficiency of an engine, it is necessary to have an appropriate scavenging area and swirl strength for the load rotational speed or outside air conditions, and in general, a partial load requires a strong swirl, but there is a drawback that it cannot cope with it. be.

An object of the present invention is to provide a scavenging control device for a uniflow scavenging internal combustion engine that eliminates the drawbacks of the conventional device and can achieve high performance over a wide range.

[Failure to solve the problem]

The scavenging control device for a uniflow scavenging internal combustion engine according to the present invention has a scavenging hole whose inflow angle is narrower at the upper part of the hole and smaller at the lower part, and at the same time reduces the scavenging area by closing from the lower part during partial load. The above object can be achieved by making the swirl strength variable to match the load and rotation speed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In the figure, 4 is a cylinder liner, 41 is a scavenging hole, and as in FIG.
In the case where T>θSB, a variable swirl device 7 is installed, and this variable swirl device 7 is provided with a scavenging hole inlet area control section 71 that opens and closes the scavenging hole by partially covering the scavenging hole. There is. 72 is variable swirl device 7
In the drive unit, 73 is the pawl, and 74 is a motor that moves the pawl 73 from side to side.

In the case shown in the figure, the variable swirl device 7 is configured such that a groove is provided at the lower part of the scavenging hole 41 of the cylinder liner 4, and it is configured to be able to fit into this groove and slide. There is.

Next, the operation of the above embodiment will be explained.

FIG. 2 shows three positional relationships when the variable swirl device 7 is operated.

FIG. 2(a) shows the position of the swirl control devices 7, 71 when the engine output is in the normal output or high load range, and exhibits the same performance as the conventional device shown in FIG. 4.

FIG. 2(b) shows a state in which the variable swirl device 7 is moved to the left by the motor 74 and the drive device 72, and the lower part of the scavenging hole 41 is partially covered by the area control section 71. In this state, the flow rate increases in the portion of the scavenging hole 41 that has a large ability to generate swirl, and the swirl becomes stronger.

FIG. 2(c) shows a state in which the variable swirl device 7 is moved further to the left, and the lower area of the scavenging hole 41 is covered even more by 71, and the area of the upper part where the inflow angle is large is increased, resulting in a strong swirl. You can get scavenging air.

As described above, by appropriately controlling the swirl control device in the low speed, low load and low speed, high load ranges according to the engine load/rotation speed, an appropriate scavenging hole area and scavenging swirl can be obtained. .

〔Effect of the invention〕

As described above, the scavenging air control device for a uniflow scavenging internal combustion engine of the present invention strengthens the swirl to improve scavenging efficiency in the low power range where the amount of air used is less than that at high load, and also improves the combustion efficiency by strong swirl. The air utilization rate can be improved and the combustion performance can be improved, and as a result, a two-stroke uniflow scavenging internal combustion engine with high combustion efficiency over a wide range can be realized.

[Brief explanation of drawings]

FIG. 1(,) is a front view of a scavenging control device for a two-stroke uniflow scavenging internal combustion engine according to the present invention, FIG. 1(b) is a sectional view taken along line A-A in FIG. 1(a), and FIG. is an explanatory diagram of the operation of the scavenging type control device, Figures 3 and 4 are conventional examples, Figure 3 is a longitudinal sectional view of a two-stroke uniflow scavenging type diesel engine, Figure 4 (,) is a front view of the cylinder litchi, and Figure 4 is a front view of the cylinder litchi. Figure (b) is a sectional view taken along line BB in Figure 4 (,). 4...Cylinder, 41...Scavenging hole, 7.71...
Scavenging control device, 72, 73, 74... drive device. Figure 1

Claims (1)

[Claims] In a two-stroke uniflow scavenging internal combustion engine, the uniflow scavenging type is equipped with a swirl control device that partially opens and closes the scavenging hole from the bottom of the hole and is rotatably and slidably attached to the outer circumference of the cylinder, as well as a drive device that drives the control device. Scavenging control device for internal combustion engines.