JPS60122264A - Intake device for two-cylinder and two-cycle engine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a crank chamber compression type two-cylinder two-stroke engine.

(Prior art) A crank chamber in which each cylinder with a phase difference of 180° is provided with an intake pipe and a carburetor on the same side and in parallel, and each intake pipe communicates with the crank chamber of the corresponding cylinder through a valve. In a compression two-cylinder two-stroke engine, the intake stroke to the crank chamber is shifted by 1/2 of the 360° engine cycle, so the pressure state in the intake pipe of one cylinder is exactly the same as the pressure state in the intake pipe of the other cylinder. The relationship is the opposite. However, in the past, the relationship between the pressures in the two classes of trachea was not used at all, so the intake air repeatedly flowed and stopped in the intake pipe of each cylinder, and during the intake stroke, due to the inertia of the intake air that had previously stopped, The start-up of the engine rotation was delayed, the charging efficiency decreased, and the engine output was not sufficiently increased. Also, even if reed pulp is used in addition to piston pulp or rotary pulp for the valve in the intake pipe, blowback due to the reed dance phenomenon during high-speed rotation is unavoidable. It could not be used because of the adjacent cylinder in the stroke, and this was also a hindrance in the direction of output.

In the case of a cylinder, there is a phase difference between the air column vibrations in each cylinder. For example, during the intake stroke of the second cylinder, the pressure in the intake pipe of the first cylinder is higher than the pressure in the intake pipe of the second cylinder. Taking advantage of the fact that the pressure is high over a wide range and has an opposite pressure relationship during the intake of the first cylinder, the two classes of trachea are connected with a balance tube, and even after the intake stroke of one cylinder is completed, the pressure of that cylinder side is The intake air in the intake pipe is sent to the other cylinder side through the balance tube, and the flow state of the intake air is continued.
The aim is to be able to simultaneously supply the gas to the other cylinder.

(1 (5) of the invention) Invention iJ: Each cylinder with a difference of 4 points of 1.800 is provided with an intake 811 and a carburetor on the same side and in parallel, and each intake pipe has a valve between the cylinders. An intake system for a two-cylinder, two-stroke engine characterized by connecting the crank to the crank chamber of the corresponding cylinder with a balance tube to both intake pipes.
It is. If each intake pipe is connected to the balance tube-C in this way, the vibrations within each intake pipe will interfere with each other.
Pressure fluctuations are reduced, and a relatively stable mixture ratio (air-fuel ratio) can be obtained from the carburetor installed in each intake pipe. Also, higher pressure acts on the intake pipe from other cylinders during the intake stroke,
The rise of the flow velocity at the start of intake is improved, the blowback from one cylinder can be actively sucked into the other cylinder, and blowback to the carburetor side is prevented. Furthermore, since the air-fuel mixture is supplied to each cylinder from both the intake pipe and the balance tube, the carburetor can be made smaller, and acceleration performance can be expected to be improved by reducing the carburetor bore. Intake passage resistance is also reduced.

(Example) Next, it will be explained with reference to the drawings. The first cylinder E+ is the first cylinder, B
2 is the second cylinder, and the second cylinder corresponds to each part of the first cylinder E+.
Each part of the cylinder Ez is indicated by the same symbol with a dash (''). In the figure, 1 (also 1') indicates the cylinder;
2 is a piston, 3 is a combustion chamber above the piston, and 4 is a spark plug. Reference numeral 5 denotes an exhaust port, which is opened and closed by the pinuton 2 toward the combustion chamber 3 and communicates with an exhaust pipe 6. The scavenging hole 7 is also opened and closed by the piston 2, and communicates with the crank chamber 1o in the crankcase 9 through the scavenging passage 8. The intake air O1l opened on the inner surface of the cylinder 1 is also opened and closed by the piston 2, and cooperates with the piston 2 to form a piston valve. 12 is an intake pipe dedicated to the first cylinder E1, 13 is a carburetor also dedicated to the first cylinder E1, and 14 is an air cleaner, which can also be used as the one for the second cylinder E2. 15 is a piston pin, 16 is a connecting rod, 17 is a crank pin, and ]8 is a crankshaft. The second cylinder T322 has the same structure as the first cylinder E1 except for a phase difference of 180 degrees.

Reference numeral 20 denotes a balance tube that also serves as an intake pipe, one end of which opens at a portion of the intake pipe J2 close to the intake port 11, and the other end of which opens at a location close to the intake port 11' of the intake pipe 12'.
,ing. The balance tube 20 is designed to be thick enough to serve as an intake pipe and as short as possible.

Figure 3 shows the intake pipe internal pressures of both cylinders E+ and B2. In the figure, 1' and nC are intake ports open;
1-)C is the bottom dead center, and TI')C is the second dead center. As is clear from this figure, in a two-cylinder engine with a phase difference of 1.80°, the intake period (engineering no.
Compared to the intake pipe internal pressure of the two medium-temperature cylinders ■I]2, the intake pipe internal pressure of the first cylinder E1 is high over a fairly wide crank angle range shown by the hatching, so /Clanance tube 20 (Figure 1) During this period, flow occurs from the first cylinder side intake pipe 12 through the balance tube 20 to the second cylinder side intake pipe 12', and the intake pipe 12' flows to the second cylinder E2.
The air-fuel mixture is supplied from both the balance tube 20 and the balance tube 20. During the intake period of the first cylinder E1, the excess air-fuel mixture passes through the balance tube 20 from the second cylinder side and enters the first cylinder E1.
Supplied to the cylinder.

(Operation) Next, the general operation will be explained. From the state shown in Figure 1, the crankshaft 18 rotates in the direction of the arrow, and the piston 2 reaches the top dead center =
When the predetermined position of L is reached, the air-fuel mixture that has been compressed in the P combustion chamber 3 is ignited and burned by the spark from the spark plug 4.
Explosive pressure is applied to piston 2. During the downward stroke of the piston 2 past the top dead center, the exhaust port 5 is opened by the piston 2.
When the combustion chamber 3 opens, the combustion gas in the combustion chamber 3 is discharged to the exhaust pipe 6,
The pressure inside the combustion chamber 3 is reduced. Air intake (E 1
1 is closed, fresh air in the crank chamber 10 is pre-pressurized by the lowering of the piston 2, and when the scavenging hole 7 is opened by the piston 2, a scavenging action is performed. Immediately before the intake port 11 is closed by the piston 2, the fresh air that has started to be pre-pressurized in the crank chamber IO is blown back into the intake pipe 12, and the intake pipe 12
Due to the water hammer effect of the intake air flowing in the direction of the intake port 11, air column vibrations with large pressure fluctuations occur in the intake pipe 12 (3rd
figure). And in the first cylinder: After the + intake port 11 is closed,
The pressure inside the intake pipe 12 changes as shown in Fig. 3 until the piston 2 passes the bottom dead center and the intake pipe II opens again.
Since the second cylinder E2, which has a different phase of 800 degrees, is exactly in the intake period (InO to InC), the first
Crank angle range with high pressure on the cylinder side (hatched part)
At this time, the air-fuel mixture including blowback flows from the intake pipe 12 through the balance tube 2o to the intake pipe 12'. Piston 2
On the other hand, during the intake period when the intake port IJ is opened by the piston 2, during the stroke where the
The air-fuel mixture including blowback is supplied from the intake pipe 12' of the cylinder E2 through the balance tube 2o and the intake pipe 12 to the crank chamber 1o.

(Effects of the Invention) As explained above, according to the present invention, each intake pipe 12.1
Since there is a phase shift in the telephone pole vibration of 2', each intake pipe 1
2.12' are communicated through the balance tube 20 to interfere with each other's vibrations, reducing pressure fluctuations in the intake pipe, and achieving a relatively stable mixing ratio (
air-fuel ratio). Furthermore, positive pressure from other cylinders is applied to the intake pipe during the intake stroke to continue the flow state in the intake pipe, and furthermore, to supply blowback from other cylinders,
This increases the rise in flow velocity at the start of intake, and together with the substantial increase in the area of the intake passage, it is possible to improve the output performance of the engine. Each cylinder is supplied with air-fuel mixture from both a dedicated intake pipe and a balance tube, so the bore of the dedicated carburetor can be made smaller, creating a good air-fuel mixture even at low speeds and improving acceleration. do. It also reduces the cost of the vaporizer.

[Brief explanation of drawings]

Fig. 1 is a structural schematic diagram of a two-cylinder engine to which the present invention is applied, with cross sections perpendicular to the crankshaft of each cylinder arranged side by side, Fig. 2 is a schematic cross-sectional view taken along line A-A in Fig. 1, and Fig. 3 is a crank angle diagram. 2 is a graph showing changes in intake pipe internal pressure with respect to FIG. 2
・Piston (pinuton valve), lO・・crank chamber (
Pre-pressure chamber), 11... Intake port, 12... Intake pipe, 13
...Carburetor, 20...Balance tube, E]...1st cylinder, E2...2nd cylinder Patent applicant Kawasaki Heavy Industries, Ltd.

Claims (1)

[Claims] A two-cylinder crank chamber compression type in which each cylinder has an intake pipe and a carburetor on the same side and in parallel with a phase difference of 180°, and each intake pipe communicates with the crank chamber of the corresponding cylinder through a valve. An intake system for a two-cylinder two-stroke engine, characterized in that both tracheas of the two-stroke engine are connected by a balance tube.