JPS59533A - Two-cycle engine - Google Patents

Abstract

PURPOSE:To make it possible to keep a high scavenging pressure at the time of low and medium speed operations of the engine by a method wherein a check valve corresponding to a throttle valve is provided in a scavenging passage close to the opening in the cylinder. CONSTITUTION:A fresh gas sucked into a crank chamber 9 is pressurized within the crank chamer 9 because the check valve 2 for controlling the flow rate of a scavenged fresh gas is provided near the outlet of a scavenging port 1. When the engine is operating at the low and medium speeds with the opening degree of the check valve 2 kept small, the pressurized fresh gas becomes a high speed and high pressure scavenging stream 8 and is fed into the upper part of the cylinder 5. On the other hand, when the engine is rotated at hgih speed and with full load, the opening degree of the check valve 2 becomes large so that the engine maintains the same performance as the conventional engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in two-stroke engines. In general, a major factor that affects the performance and fuel efficiency of a two-stroke engine is the exchange of fresh air and exhaust gas, the so-called scavenging effect.

In conventional engines, the scavenging port that opens into the cylinder does not change its position and has a fixed area, making it difficult to achieve both low-speed performance and high-speed performance.

In addition, irregular combustion at low speeds and low loads, which is characteristic of 2-cycle engines, and large amounts of fresh gas blowing through at medium speeds and heavy loads, etc.
C. This is the fate of two-stroke engines as it increases CO and fuel consumption.

The present invention aims to improve the above-mentioned drawbacks of the conventional engine, and aims to eliminate the above-mentioned drawbacks by increasing the scavenging pressure of the engine, especially during medium-speed and low-speed loads. The throttle valve installed in the carburetor was eliminated, and a throttle valve corresponding to the throttle valve of the carburetor was installed in the scavenging passage near the scavenging port opening into the cylinder, and pressurized fresh gas in the crank chamber was passed through the spark plug. It blows vigorously into nearby cylinders.

The present invention will be explained below with reference to the drawings. FIG. 1 is a block diagram according to the present invention.

Although the method of sucking fresh gas into the engine shown in FIG. 1 is a so-called reed valve method, the present invention is not limited to any method of sucking fresh gas into the crank chamber.

A piston valve method, a rotary disk method, a piston reed valve method, or any other method may be used.

Referring to FIG. 1, the reference numerals are as follows: 1 is a scavenging port, 2 is a throttle valve, 8 is a scavenging flow, and 10 is a carburetor.

FIG. 1 shows the principle of operation of the present invention when the engine is running at low speed.

First, since the engine does not have a throttle valve to control intake air in the carburetor 10 even at low speeds, the maximum amount of fresh gas is taken into the crank chamber 9 as in the case of a conventional engine under full load.

In conventional engines, the fresh air taken into the crank chamber is directly sent into the cylinder from the scavenging port at low speed and low pressure, but in the present invention, the fresh gas taken into the crank chamber 9 is Since the throttle valve 2 that controls the scavenging flow rate is provided near the scavenging port outlet, the gas is pressurized in the crank chamber 9 during medium and low speed rotation when the throttle valve 2 is not opened much. The fresh air gas is throttled by the throttle valve 2 and sent into the upper part of the cylinder 5 as a high-speed, high-pressure scavenging air flow 8.

As shown in the figure, at low speeds, the amount of scavenging gas sent into the cylinder 5 is reduced and only a small amount of scavenging gas 8 is sent into the cylinder 5, so that low speed rotation is maintained.

Furthermore, at medium speeds, the opening degree of the throttle valve 2 is greater than at low speeds, so the amount of scavenged air is greater than at low speeds, so that medium speed rotation is maintained.

At high speeds or under full load, the throttle valve 2, which corresponds to the throttle valve, is fully open or close to fully open, so it has the same performance as a conventional engine.

In FIG. 1, a throttle valve 2 is provided with a plate-shaped plate so as to close a scavenging port, and one end of the throttle valve 2 is connected to a control wire 13.

By operating the control wire 13, the opening degree of the throttle valve 2 is adjusted.

The throttle valve 14 in FIG. 2 is a semicircular opening/closing valve having a diameter approximately twice the inner diameter D of the scavenging port 1.

The throttle valve 14 is connected to a rod 15 and rotates around a shaft 16 to open and close the scavenging port as shown in the figure.

In either of the above valve systems, the shape is such that there is no resistance to the scavenging air flow when fully open, and the shape is such that at medium speeds or lower, the intake air pressure in the crank chamber 9 can be efficiently converted into the speed of the scavenging air flow. It is.

The present invention has significant features that are not found in conventional engines at low and medium speeds, which are practical rotational speeds.

That is, in the present invention, by eliminating the throttle valve in the carburetor and replacing it with a throttle valve near the scavenging port outlet, the maximum intake air amount of the engine can be maintained at all times from low speed to high speed, regardless of the load. It is possible to draw air into the chamber 9.

As a result, high scavenging pressure can be maintained even when the engine is running at low or medium speeds.

In short, in conventional engines, output control was performed by a carburetor, but according to the present invention, output control is performed by a throttle valve installed in the scavenging air port, so the crank chamber is always filled with fresh air gas. This is what we are doing.

Therefore, the scavenging air throttled by the throttle valve 2 can be sent to the vicinity of the upper spark plug of the cylinder 5 at high speed under high scavenging pressure.

As a result, a high-density scavenging air flow can be obtained at low and medium speeds, which enables efficient scavenging and exhaust, thereby ensuring reliable ignition.

That is, reduction of rotational unevenness due to irregular combustion, HC. C.O.
In addition, the torque performance at low and medium speeds is improved, and the engine revs up faster.

Furthermore, since the scavenging air flow reaches the vicinity of the spark plug in a short time, combustion is possible even at a leaner A/F ratio than in the past, which reduces fuel consumption as well as the above effects.

The effects of the present invention have been described above, and furthermore, according to the present invention, unlike conventional engines, the performance of the engine can be improved without sacrificing performance at low speeds, and it has a simple configuration. This is a 2-stroke engine that can take full advantage of the advantages of a 2-stroke engine: light weight, small size, and high performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main structure of the present invention. FIG. 2 is a diagram showing a throttle valve portion provided at the scavenging port, and is a sectional view showing the throttle valve portion having a configuration different from that of the embodiment shown in FIG. 1. Explanation of symbols 1... Scavenging port 2... Throttle valve 3... Spark plug 4... Cylinder head 5... Cylinder 6... Exhaust port 7... Piston 8... Scavenging flow 9... Crank chamber 10... Carburetor 1
1... Reed valve 12... Choke valve 13... Control wire 14... Throttle valve 15... Rod 16...
Axis patent applicant Zen Ishikawa■

Claims (1)

[Claims] In a two-stroke engine, the throttle valve in the carburetor is eliminated so that the crank chamber is constantly filled with fresh air gas, and on the other hand, in the scavenging port that opens into the cylinder, the throttle valve is installed in the scavenging passage adjacent to the opening. A two-cycle engine is equipped with a throttle valve corresponding to the throttle valve, and by opening and closing the throttle valve, a high-speed, high-pressure scavenging air flow is sent into the cylinder to obtain high scavenging efficiency, and the output is adjusted by changing the scavenging flow rate.