JPS6196129A - Two-cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduced the blow-by of an air-fuel mixture due to scavenging in time of high load, by scavenging the inside of a cylinder with air out of an air blower driven by exhaust energy, in advance of feeding each cylinder with the air-fuel mixture by dint of pressure inside a crankcase. CONSTITUTION:With a piston 1 going down, first an exhaust port 2 is made to open, driving a turbine 3 by a spout of sudden exhaust gas, and air is fed, with pressure, to an accumulator 5 by a blower 4 situated on the same axis. Next, air is fed to the inside of a cylinder 8 from a preceding scavenging air port 7 through a control valve 6, and combustion inert gas is scavenged. Successively an air-fuel mixture feed port 9 is opened, and an air-fuel mixture is fed to the cylinder 8. At this time, pre-cycle combustion gas inside the cylinder 8 is pushed out most of it by the preceding air scavenging, and air is charged instead so that a little quantity of relatively thick mixture in fuel density is supplied in consequence whereby it is able to respond to the load required by an engine.

Description

Detailed Description of the Invention A two-stroke engine with premixed crank chamber has advantages over a four-stroke engine, such as a simpler structure, lower cost, and higher specific output. As a result, more fresh air blows through, resulting in poor fuel efficiency and increased MO in the exhaust gas.
However, when the load is low, there is a large amount of residual inert gas in the cylinder, which inhibits combustion, leading to misfires and unstable combustion.

The present invention mainly aims to reduce the air-fuel mixture blow-through caused by scavenging at high loads (high air supply ratios), which is a drawback of two-cycle engines, and also reduces the pump work required for scavenging, which extends over the entire operating range of S2-cycle engines. The purpose is to improve combustion, increase thermal efficiency, and reduce exhaust pollution.

The cause of air-fuel mixture blow-by in a two-stroke engine with a crank chamber compressor mixture is that during the scavenging stroke, the air-fuel mixture (gas) expels the residual combustion gas (gas) in the cylinder, which is ineffective due to mixing and diffusion in the boundary layer between the gases. This is because it is difficult to control the flow of scavenging air that passes through the exhaust hole, which limits operability and thermal efficiency. As the amount increases, fuel efficiency and exhaust gas components worsen, and even if you try to reduce blow-through by suppressing the air supply ratio, the amount of reverberant inert gas increases, inhibiting combustion and reducing both fuel efficiency and drivability. By performing preliminary scavenging using accumulated air driven by exhaust energy and then supplying the air-fuel mixture or fuel into the cylinder, this drawback in engines can be virtually eliminated, and the blow-by of the air-fuel mixture (fuel) can be virtually eliminated. It is characterized by enabling stratified distribution of density and by eliminating combustion inert gas from the previous cycle as much as possible to maintain stable operability over the entire engine operating range and improve thermal efficiency. It is.

The main f! of the present invention! The A-unit configuration consists of a blower that is driven by exhaust energy in a two-stroke internal combustion engine, an air pressure storage chamber to temporarily hold the pressurized air, and a supply of the pressured air according to engine rotation and load. An embodiment of the present invention comprising an air flow control valve for supplying fuel or air-fuel mixture to the cylinder in advance and an air scavenging flow path for supplying fuel or air-fuel mixture in advance to the cylinder will be described with reference to FIG. 1.
, in Fig. 2, the exhaust hole (2) first opens as the piston (1) descends, the turbine (5) is driven by the sudden jet of exhaust gas, and the air is pumped into the pressure accumulation chamber (5) by the IK feeder C4) located on the same axis. ). The air flow rate and timing are adjusted by a control valve (6) that operates in synchronization with the engine rotation, and the air enters the cylinder (8) through the advance scavenging air hole (7) that opens next when the piston (1) descends. It performs a scavenging action to expel the combustion inert gas that is supplied and remains after pulldown. In this case, part of the air (the leading part,
(near the exhaust hole) is short-circuited to the exhaust hole and blows through into the exhaust, but this does not cause engine loss. Next, the mixture supply hole (9) is opened and the mixture is supplied into the cylinder (a), but in this case, most of the previous cycle combustion gas in the cylinder is removed by the preceding air scavenging. is pushed out,
Instead, because it is filled with air, the required engine load can be met by supplying a small amount of a relatively intoxicating mixture of fuel density.

Generally, in a two-stroke premix engine, it is known that the amount of fresh air blown out increases as the air supply ratio increases.

It is also known that an increase in air supply increases pump work and friction loss.

According to the present invention, since the cylinder is filled with advance air, the required performance of the engine can be maintained at a lower air supply ratio (however, the fuel density is high) by reducing the amount of air supplied to the fuel mixture. As a result, the loss of air-fuel mixture blowing, which conventionally increases when high supply gas is achieved, is drastically reduced, and at the same time, the pump work required for conventional high supply unrivaled supply is reduced, resulting in a dramatic improvement in engine thermal efficiency. Furthermore, the concentration of residual gas in the cylinder is significantly reduced by the amount of li in the preceding scavenging air, so an internal cooling effect can be expected and it is also possible to increase the compression ratio, and the synergistic effect is large and the efficiency improvement effect as a heat engine is large. There is something.

In the present invention, when the air-fuel mixture is supplied, the previous cycle combustion gas in the cylinder is already cleaned and the cylinder is filled with air, and the engine can be operated by supplying only fuel.

In the embodiments of the present invention, the configuration characteristics and effects of a crank chamber compression premixed two-stroke engine have been explained.However, in both the fuel injection supply system and the compression ignition combustion system, advance air scavenging using exhaust energy, which is the basis of the present invention, is used. By applying it, it is clear that the pump work required for conventional scavenging is reduced and the efficiency of public institutions is improved.Although the example shows air supply by turbine drive, other methods that utilize exhaust energy It goes without saying that similar effects can be obtained in a complex method, for example.

Another feature of the present invention is that stratified air supply can be easily performed. In other words, the inside of the cylinder is scavenged only with air before fuel is supplied, and by supplying fuel or mixture by any method without coming close to the exhaust hole, a mixture that can be ignited is created near the main stopcock. This makes it possible to form air masses and carry out lean mixture biscuits for the entire cylinder, contributing to improved thermal efficiency.

As mentioned above, the present invention utilizes the energy of exhaust gas that is ineffectively discharged to perform scavenging, which is a characteristic of 2-cycle engines, and the supercharging effect used in 4-cycle engines In other words, when used in conjunction with a crank chamber premix compression cycle, even if the amount of advance scavenging air is relatively small, it prevents the fuel components from blowing through and increases the filling efficiency of the mixture. By eliminating the inert gas in the cylinder, stratified air supply is possible, and the compression ratio can be increased, which improves the specific output and fundamentally changes the heat balance of the engine. , The burden on the exhaust energy conversion equipment system for this purpose is light, and it can be said that it is a major feature that it is advantageous in terms of life and cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional diagram illustrating the equipment configuration near the air-fuel mixture supply hole of a premixed crank chamber pressure W42 cycle engine according to the present invention, and FIG. 2 is a diagram illustrating the configuration in a vertical section centered on the exhaust hole. In the figure, (1)...piston, (2)...exhaust hole, C
3) - Exhaust turbine, (4) Air blower,
(5) --- Air pressure accumulation chamber, <6) --- Movable control valve,
(No...Advanced air scavenging hole, (8)...Cylinder interior, (9)...Mixture supply hole% (1o) - Carburetor, (11)...Ignition plug, Solid line arrow indicates exhaust gas The dotted arrow indicates the scavenging air flow.

Claims (3)

[Claims] (1) A crank chamber compression premix type two-stroke internal combustion engine characterized in that an air blower driven by exhaust energy scavenges the cylinders with air prior to supplying the air-fuel mixture into the cylinders using the crank chamber pressure. (2) A small high-speed two-stroke internal combustion engine characterized by scavenging air in the cylinder with an air blower driven by exhaust energy, and supplying fuel or air-fuel mixture into the cylinder by another device to perform compression ignition combustion. (3) The scope of the patent is characterized in that it is provided with a pressure accumulation part that accumulates pressure of air generated by an exhaust energy-driven blower, and has a movable opening/closing valve that supplies the accumulated air in a metered amount into the cylinder according to the rotation and load of the engine. The two-stroke internal combustion engine according to (1).