JPS5835225A - Spark-ignition 2-cycle engine - Google Patents

Abstract

PURPOSE:To reduce the mixing of exhaust to fresh air and increase scavenge efficiency, in a uniflow unsymmetrical scavenging 2-cycle engine of overhead intake-scavenge valve type, by causing a positive swirl flow of the fresh air and performing scavenging action at replacement of scavenged air with the fresh air. CONSTITUTION:A combustion and swirl forming chamber 7 is provided in a cylinder head part to cause a positive swirl flow of fresh air and perform scavenging action at replacement of scavenged air with the fresh air. A piston 2 is lowered, if exhaust ports 12 in the lower wall of a cylinder 1 are opened, exhaust is discharged to the outside of the cylinder rapidly at a time. Thereafter, overhead intake and scavenge valves 4 are opened to a position about half the chamber 7, and replacement of scavenged air with fresh air, provided with a swirl, can be performed in the chamber 7 till the exhaust ports 12 are closed, after closing of the exhaust ports 12, the intake and scavenge valves 4 are closed to transfer the piston to a compression stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spark-ignition two-stroke engine having a vortex flow and a high-speed combustion chamber.

In recent years, due to global energy shortages, the price of crude oil has skyrocketed, and the development of alternative energy sources has become increasingly serious, making energy conservation a major social issue. In addition, automobiles and the like are increasingly required to have engines with higher thermal efficiency.

On the other hand, pollution caused by automobile exhaust gas has become a social problem, and in order to purify the exhaust gas in general-purpose 4-stroke engines, many people are asking whether the fuel is diluted as much as possible during general use to reduce unburned components in the exhaust gas. It has become to.

When the air-fuel ratio is reduced in this way, the flame propagation speed becomes slower. Therefore, it is necessary to add a swirl (rotating flow) during intake, to create a sub-combustion chamber, and use jets and squish from the sub-combustion chamber to stir combustion as quickly as possible, and to increase the distance of flame propagation in the combustion chamber. The aim is to improve fuel efficiency by eliminating the traditional shape of the combustion chamber, and as a result, we have succeeded in achieving considerable results.

However, in the case of a 4+J cycle engine, the piston speed is high, so the combustion process time is short, and the ignition timing must be advanced, and the exhaust valve begins to open early (on average, around 55 degrees before bottom dead center). 4-stroke engines have their own drawbacks, such as the high inertia of the connecting rod.

Furthermore, since combustion is slow in the case of Diegel engines, there is a deficiency in the ability to burn quickly near top dead center, which is the ideal for piston strokes.

As proof of this, it has been found that increasing the speed causes incomplete combustion.

In the case of a two-stroke engine, unlike a four-stroke engine, it does not have an independent exhaust stroke, so its scavenging efficiency greatly affects performance.

Scavenging methods can be roughly divided into loop scavenging, cross scavenging, and uniflow scavenging. In loop scavenging and cross scavenging, the exhaust hole must be installed at a relatively high position in the cylinder, so the effective stroke of the piston is It has the disadvantage that it tends to become shorter. On the other hand, the Coniflo scavenging system has a valve exhaust type in which exhaust gas is discharged from a valve in the cylinder head and fresh air is supplied through a scavenging hole in the lower wall of the cylinder; There is a valve operated type in which the exhaust gas is discharged from one hole in the cylinder.In the valve exhaust type, the valve is heated by the high temperature exhaust gas, causing the valve to sag, and a large amount of exhaust gas must be discharged through an overhead valve. Therefore, it is necessary to use a large valve with a large exhaust capacity compared to the fresh air capacity, and to increase the number of T and L valves! In this point valve pumping type, the exhaust hole is opened by the piston, so the hole area increases rapidly and ideal lJI air is ejected, and the overhead valve is cooled and heated by fresh air. However, since the shadow of the scavenging air flow is created at the bottom of the valve, there is a drawback that fresh air and exhaust air are mixed due to the vortex flow, reducing the scavenging efficiency.

The present invention aims to improve the shortcomings of general-purpose engines as described in -F, and to provide an excellent engine that incorporates the advantages of each engine as much as possible.・This engine is basically a spark ignition two-stroke engine with an overhead valve intake system.

In the valve scavenging type of the Coniflo scavenging system, the mixing of the exhaust gas due to the vortices that cause the shadow of the scavenging air flow on the valve 1 side is eliminated by a specially shaped combustion chamber formed at the bottom of the overhead intake air valve. In addition, it is a spark ignition type, and the rotation speed is half that of a 4-cycle engine.
Although it is a 2υ cycle engine, each stroke can take a long time to operate efficiently, and the compression ratio is near the top dead center, where the fuel is injected in layers, so the heat of compression causes spontaneous ignition. ^ Compression ratio and 1 to the extent that it does not cause
In addition, due to the low rotational speed and the large exhaust hole, the position of the exhaust hole can be set low, resulting in high suction and scavenging efficiency, and the effective stroke can be set as long as possible. Like a diesel engine, it does not throttle the air supply, so it has a large torque even at low speeds under partial load, making it suitable for use in a wide range of applications, including passenger cars, buses, and trucks.

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

1 is a cylinder, 2 is a piston, 3 is a squish portion of the cylinder head, and an intake valve 4 is provided above the squish portion 3.

The intake/return valve 4 is normally pressed onto the valve seat 5 by a spring.
Controlling the warm canister air entering the expansion chamber 8 from the suction trachea 6? l
φ. Reference numeral 7 denotes a special bowl-shaped combustion chamber/vortex forming chamber formed between the intake air valve 4 and the expansion chamber 8, the entire wall surface of which is an arcuate surface, and the opening is slightly constricted and elongated. Reference numeral 9 denotes a fuel supply passage connected to this combustion chamber/vortex type IIA to 7. Inside this passage 9, there is a fuel injection valve 10 and a spark plug 1 below it.
Attach 1. 12 is an exhaust hole provided in the lower wall of the cylinder and communicates with 1 exhaust pipe 13.

The present invention is constructed as described above, and its operation will be explained next.

The present invention is a spark ignition type 4-cycle engine with half speed 1&C.
Based on the stroke diagram shown in FIG. 4, the compression stroke will be explained. The fuel injection valve 10 is opened during the engagement phase of the compression stroke to inject fuel. Here, the fuel is first injected into the combustion chamber/vortex forming chamber 7 through the passage 9, and then flows into the expansion chamber 8 in the form of a layer. Immediately after the fuel injection valve 10 is closed and the fuel is injected, a spark is ignited by the spark plug 11 just before top dead center, resulting in rapid stratified combustion due to high compression τ and high vortex flow, squish, etc. Then, when the piston 2 descends and the exhaust hole 12 in the lower cylinder wall is opened, the exhaust gas is discharged out of the cylinder at once.
is opened to about half of the combustion chamber/vortex forming chamber 7, scavenging fresh air is exchanged with a vortex in the combustion chamber/vortex forming chamber 7 until the exhaust port 12 is closed, and after the exhaust port 12 is closed, Then, a slight supercharging is performed, the intake air valve 4 is closed, the engine moves to the compression stroke, and the same cycle as described above is repeated.

As described above, the present invention provides a special bowl-shaped combustion chamber/vortex forming chamber in the cylinder head part, and actively generates a vortex of fresh air in the combustion chamber/vortex forming chamber when C1 scavenging fresh air is replaced. Since it has a scavenging effect, there is less mixing of fresh air exhaust, and it also performs rapid stratified combustion in the combustion chamber and vortex forming chamber of the fuel injection and ignition shaft, resulting in ideal combustion. , has high thermal efficiency, and has a configuration that does not restrict supply air, so it has large torque even at low speeds under partial load, and because of its high temperature and high compression ratio, it can use a variety of fuels and has a low rotational speed. It has excellent effects such as less mechanical loss due to the inertia of the piston connecting rod.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a vertical cross-sectional view of a cylinder, FIG. 2 is a front view of the cylinder head and end, FIG. 3 is a perspective view of the cylinder head, and FIG. 4 is a stroke diagram. It is. 1...Cylinder, 2...Piston, 3.
...Squish part, 4...Suction and scavenging valve, 5...
Valve seat, 6... Intake air pipe, 7... Combustion chamber/vortex forming chamber, 8... Expansion chamber, 9... Fuel supply passage, 10... Fuel injection valve, 11... Ignition Plug, 12...Exhaust hole, 13...Exhaust pipe. Patent Applicant Agent Name Section 20!1 Body 3 (!1 $1 Figure Procedure Amendment (Spontaneous) October 5th, 1980 Indication of the case of Mr. Haruki Shimada, Commissioner of the Japan Patent Office 1983 Patent Application No. 183877
Title of the invention Relationship to the case of person who amends a spark-ignition two-stroke engine Patent applicant, agent
Person 〒050 Date of amendment order Showa year Month Date Subject of amendment Detailed explanation of the invention in the specification Procedural amendment rejected 1982 2 [19 Haruki Shimada, Commissioner of the Patent Office 1, Indication of the case 1988 Special Permission No. f3887
2. Title of the invention Spark-ignition two-cycle engine 3. Relationship with the case of the person making the amendment Patent Applicant 4, Representative
Mr. 〒650 7. Amendment) Contents I will revise the attached document.

Claims (1)

[Claims] In the UNIFLO asymmetrical scavenging type overhead scavenging air valve type two-stroke engine, a fuel injection valve and a spark plug are installed below it, and a special bowl-shaped swirl forming chamber that communicates with the expansion chamber is formed at the bottom of the overhead intake valve. A spark-ignition two-stroke engine that generates a rotating vortex when the engine is activated.