JPS62113824A - Intake scavenge system preceding air scavenge action for two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the blow-bye of fuel for improving thermal efficiency by forming a scavenge passage in a dual passage structure where only the upper portion of passages is communicated by a partition so that air is inducted from one passage to fill up the other passage which is communicated with a crank room. CONSTITUTION:A cylinder 1 is formed with a scavenge passage 2 having two flow paths A and B where a partition is provided for communicating them with each other by an upper section C. And a check valve 5 is provided to an air suction port 4. When a check room 7 becomes negative in pressure with a piston 6 elevated, air at atmospheric pressure flows in from a flow path A' via the flow path B toward the crank room 7. Then air from the flow path A is turned over int the upper section C for filling the flow path B' with air required for preceding a scavenge action toward the direction to the crank room 7. On the other hand, a mixture is supplied to the crank room 7 from a carburator 8 via one side 9 of the check valve 5 where a ratio of the mixture to the volume of preceding air is regulated by matching between the carburator 8 and the sluice section of the check valve 5.

Description

DETAILED DESCRIPTION OF THE INVENTION As a means to prevent air-fuel mixture blow-through during high loads, which is a drawback of crank chamber compressor mixed two-cycle engines, air scavenging is performed in advance of air-fuel mixture scavenging.
It is thought that if the residual gas is removed by air, the blow-through of the air-fuel mixture that is subsequently supplied will be reduced, thereby improving fuel efficiency and reducing exhaust gas components. This predicts the remaining amount of air that was previously supplied into the cylinder,
The next air-fuel mixture to be supplied is one with high fuel density, and if there is some remaining amount of preceding air in the cylinder, it is possible to form a comprehensive mixture ratio and air supply ratio in the cylinder even by reducing that amount. This is based on the idea that the proportion of air-fuel mixture blowing at the front of the air-fuel mixture, which conventionally accompanies air-fuel mixture scavenging, will be reduced.

However, this method requires the formation of an air feeding device and an air flow path, and although it is complicated, it is ineffective and increases the cost.Therefore, there is no practical example yet.

The inventor previously confirmed this effect using a gas engine (published patent publication No. 58-5423).

The present invention provides a concrete method that can effectively solve the problems described above with a simple structure, and improves engine thermal efficiency by controlling fuel blow-through without impairing the features of a two-stroke premix engine with a simple structure. The purpose is to reduce harmful components in exhaust gas. Another purpose is to construct a vine circuit that performs air intake or scavenging during the casting or die-casting process in order to improve the performance of the engine without increasing the machining process or the number of parts during production. .

The present invention provides a two-stroke engine for crank chamber compression premixing, in which an air intake passage is formed closer to the cylinder scavenging passage than a check valve provided near the intake hole of the crankcase, and this is used as the cylinder mixture scavenging passage. They communicate in parallel near the cylinder scavenging holes in the scavenging air passage, and the negative and positive crank chambers allow air to fill up to the scavenging passage near the crankcase, allowing air to be supplied into the cylinders in advance before the air-fuel mixture is supplied from the crank chamber. The scavenging air passage structure of the cylinder is made into a double structure with partition walls etc. as shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings.

It is installed in cylinder (1)! @Airway (2) is partition m
The ASB has a double channel structure having (3), and is connected through the upper (0) point. There is a check valve (5) in the air intake port (4), and now the piston (6)
) rises, the crank chamber (7) becomes negative pressure, so B
Atmospheric pressure air flows from the A' flow path toward the crank chamber through the flow path. The A path is an air suction flow path, and the air from the A path is reversed at the zero point, and the B' flow path is filled with air necessary for advance scavenging in the direction of the crank chamber (7).

On the other hand, inside the crank chamber (7) there is a carburetor (marked with a check valve (5)).
) The air-fuel mixture is supplied through one side (9) of the air gap, and the ratio of this mixing percentage to the preceding air layer is determined by matching the carburetor with the check valve partition as shown in Figure 1. With a check valve structure, the air-fuel mixture is mainly used at low loads (low supply air ratio), and at high loads (
For a high air supply ratio), adjustments such as increasing the amount of preceding air can be easily made.

In this case, a part of the air that is previously supplied into the cylinder is inevitably exhausted together with the exhaust gas, but a part of it remains in the cylinder. Therefore, the amount of mixture 'A' to be supplied into the cylinder after air scavenging and its fuel density are required to be relatively dense in order to achieve the overall air ratio in the cylinder. It is obvious that the target output can be maintained with a reduced amount of scavenging air, and the conventional head mixing blowout (head throughput loss) associated with a high supply air ratio is reduced.

It is known that in conventional two-stroke premix engines, the amount of dead air-fuel mixture at high loads reaches as much as 30%.
ing. The causes of this are as mentioned above: ■ The leading air-fuel mixture is dispersed into the residual gas in the cylinder, gets mixed up, and jumps out into the exhaust system with exhaust gas, and is discharged ineffectively. There are three known causes: short-circuiting and ineffective exhaustion, and ■ until the piston rises and closes the exhaust hole, the air-fuel mixture supplied into the cylinder overflows with the remaining gas, but the present invention As shown in Figure 1, by applying the air advance method and forming an air layer on the exhaust port side, the ineffective blow-through of fuel components due to the three major blow-throughs mentioned above is greatly reduced, improving the thermal efficiency of the engine. However, a major effect of the present invention is that the scales also reduce harmful components in exhaust gas.

Another object of the present invention is to easily put this effective method into practical use.As shown in Fig. 1, the circuit configuration is performed by aligning the cylinder and the crankcase in the die-casting or molding process. In addition to minimizing the machining process, as shown in Figure 1, one carburetor and one check valve body are separated to enable separate supply of air and mixture, thereby minimizing increases in product costs. This is also a feature of the present invention and can be said to be an effect that cannot be overlooked.

Although the embodiments of the present invention have been shown for a crank chamber indenter mixed two-stroke scavenging type engine, the present invention can also be applied to other loop scavenging types or two-near zero scavenging types without being particularly restricted depending on the type of fuel. It is a vine that increases the effect by applying it.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a crank chamber compression two-cycle engine showing an embodiment of the present invention, and FIGS. 2 and 3 are cylinder cross-sectional views showing an example of the partition structure of the scavenging passage. ... Cylinder, (2) ... Preceding air scavenging flow path, (3) ... Partition wall, (4) ... Air intake flow path, (5) ... Check valve body, (6 ]...Piston, (7)...Crank chamber, (8)-...Amar/l
/ type carburetor, (9) ...Mixture check valve, (10)
... Air check valve, A-A' ... Air flow path, B
, B/...Mixture flow path that leads air. Figure 1

Claims (4)

[Claims] (1) In a two-stroke engine that performs scavenging with air prior to the air-fuel mixture, the scavenging passage provided in the cylinder has a double structure with only the upper part communicating through a partition wall, and one of the divided passages is Air is introduced and the other flow path leading to the crank chamber is filled with this air, and the air and mixture supply circuit is configured so that the air can be supplied into the cylinder before the mixture is scavenged into the cylinder. A crank chamber compression two-stroke internal combustion engine characterized by a structure in which cylinders and crankcases are aligned. (2) The above-mentioned patent claim is characterized in that a plurality of scavenging passages for supplying the air-fuel mixture generated in the crank chamber into the cylinder are formed on the side opposite to the exhaust hole, separate from the preceding air scavenging passage. A two-stroke internal combustion engine according to range (1). (3) Connect one carburetor body and one check valve body,
Claim (1) characterized in that the air-fuel mixture can be supplied in the direction of the crank chamber and the air can be supplied in the direction of the cylinder.
- The two-stroke internal combustion engine described in (2). (4) Set the flow path volume for advance air scavenging to 20 to 4 of the cylinder volume.
The two-stroke internal combustion engine according to claims (1) and (2), characterized in that the flow path length is within the range of 0% and the length of the flow path is longer than the piston stroke.