JPH11182252A - Two-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure smooth operation of a piston, etc., and perform effective operation of an engine by providing an exhaust rotary valve in an exhaust port provided on the top surface of an engine combustion chamber and providing a suction rotary valve in an intake port of a crank case. SOLUTION: In an engine 1 having a combustion chamber 2, a crank case 3, and a scavenge passage 4, a piston 5 is provided liftably, and a crankshaft 71 is rotated through a connecting rod 6 by reciprocating motion of the piston 5. Respective rotary valves 81, 91 for intake and exhaust are provided in an intake port 8 and an exhaust port 9 of the engine 1 respectively. The respective rotary valves 81, 91 have through holes 81a, 91a penetrating in the diameter direction, and when the through holes 81a, 91a coincide with the intake and exhaust ports 8, 9 respectively, introduction of fresh air and exhaust of combustion gas are performed. These rotary valves 81, 91 are interlock-rotated through a chain 10 by rotation of a chain gear 72 on the crankshaft 71.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke engine for the purpose of efficiently exhausting combustion gas and improving the combustion effect.

[0002]

2. Description of the Related Art Conventionally, various configurations and systems of a two-stroke engine aiming at efficient exhaust of combustion gas and improvement of a combustion effect have been proposed. Among them, the inventions having the same mechanism are listed as follows.

(1) There is a two-stroke internal combustion engine disclosed in JP-A-4-1416. The present invention has a configuration in which an exhaust port and a cylinder scavenging port are provided on the same side with respect to the center of a cylinder, and a rotary valve is provided in the cylinder scavenging port so that the port is opened so that the port opens upward from below the cylinder. Yes, intended for efficient exhaust of combustion gases.

(2) There is an engine control device disclosed in Japanese Patent Application Laid-Open No. 4-128824. The present invention provides a supercharging pressure adjusting means for adjusting a supercharging pressure by an intake supercharging means, and an exhaust timing variable means for varying a closing timing of an exhaust port. And stratified combustion is effectively performed at a low load, and uniform combustion is performed at a high load to improve the combustion effect.

(3) There is a two-stroke diesel engine disclosed in Japanese Patent Application Laid-Open No. 4-86327. The present invention provides a configuration in which a crank passage of each cylinder communicates with a communication passage, and a control valve for communicating and shutting off the crank chamber of each cylinder is provided in the communication passage, and the control valve is controlled in a low / medium load operation range. It is intended to reduce the emission of harmful components such as NOx and the knocking noise in the low / medium load operation range.

[0006]

As described in the specification, the above-mentioned inventions can be fully understood that each of them has been improved, has a novel structure, and has advantageous effects. However, on the other hand, the following problems are conceivable. That is,
The effect achieved by each invention is one-sided,
As described above, there are problems such as not being sufficient to expect an overall effect such as at least improvement of the exhaust and combustion effects, or not being structurally devised.

The inventions of Documents (2) and (3) have a structure in which the control of the engine is automatically controlled, and have a characteristic that they can be controlled by catching delicate timing, but the structure is complicated and the cost is high. Problems.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to simplify the structure and improve the exhaust and combustion effects efficiently, and to ensure the smooth and smooth operation of a piston and a rotary valve for intake and exhaust. It is intended to ensure efficient rotation of the engine.

According to a first aspect of the present invention, there is provided an exhaust port provided on the top surface of a combustion chamber of an engine having a built-in piston, an exhaust rotary valve provided in the exhaust port, and facing the combustion chamber. A two-stroke engine comprising a spark plug, a scavenging passage communicating the crank chamber of the engine with the combustion chamber, and a rotary valve for intake provided in an intake port of the crank chamber.

[0010] The present invention is intended to ensure reliable and smooth operation of the intake / exhaust rotary valve to ensure efficient rotation of the engine.

A second aspect of the present invention is a two-stroke engine having a structure in which a rotary valve for intake and exhaust is opened by a half rotation of a crank.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a rotary gear for driving a rotary valve fixed to a crankshaft (a chain gear can be replaced with another rotating medium such as a spur gear, a pulley, and the like). And an exhaust valve chain gear (hereinafter, referred to as a second chain gear) fixed to a shaft of a rotary valve for an intake valve (hereinafter, referred to as a first chain gear). Yes.)
Are linked by a chain (a chain can be replaced by another suspension medium such as a belt. The same applies to the following).
The second chain gear is rotated at a constant speed. The number of revolutions of the first and second chain gears is set to half of that of the rotary valve driving chain gear.

The operation state will be described below. As shown in FIG. 2A, when the piston is located before the bottom dead center (shown by reference to FIG. 4), the exhaust port is opened and the combustion gas in the combustion chamber is opened. Is exhausted. On the other hand, the intake port is closed.
Thereafter, as shown in FIG. 2B, when the piston is at the bottom dead center (see FIG. 4), the exhaust port is open and the combustion gas is continuously exhausted. Since the combustion chamber and the crank chamber communicate with each other through the scavenging passage, the compressed mixed gas in the crank chamber is sent to the combustion chamber through the scavenging passage. Then, as shown in FIG. 3C, when the crank is located after the bottom dead center (shown by reference to FIG. 4), the exhaust port is closed, and preparation for an explosion to be described later is started. Further, the opening of the intake port starts, and the mixed gas is introduced into the crank chamber.
It should be noted that the exhaust port is closed almost simultaneously with the scavenging passage so as to secure a long compression time and generate a strong driving force (see FIG. 4). Then, as shown in FIG.
At a stage where the crank has reached about 1/2 of the vertical dead center, the intake port is opened and the mixed gas is introduced into the crank chamber. Then, when the piston reaches just before top dead center (Fig. 4
Shown for reference. ), An explosion occurs through the spark plug. As shown in FIG. 4E, when the top dead center is reached, the explosion reaches its peak (indicated by FIG. 4). Also, the intake port is closed. At this time, an overlap state is generated between the compression and the explosion. Thereafter, as shown in FIG. 2 (f), the ignition combustion of the piston continues about 1/2 before the vertical dead center (shown by reference to FIG. 4). The intake / exhaust ports are closed. One stroke is completed by such operations and procedures. Thereafter, the operations and procedures are sequentially repeated to perform smooth and efficient combustion and generate a predetermined engine torque.

By utilizing the rotation control and the delicate opening / closing timing of the intake / exhaust rotary valves as described above,
Efficient improvement of exhaust and combustion effects can be achieved. In addition, a reliable and smooth operation and opening / closing timing of the piston and the intake / exhaust rotary valve can be ensured, and efficient rotation of the engine can be ensured. Further, since a smooth transition of the engine torque is achieved, there is a feature that is useful for reducing a shock due to a torque change. By using two scavenging passages (scavenging valves), the mixed gas can be more reliably introduced.

[0015]

An embodiment of the present invention will be described below.

Reference numeral 1 denotes an engine having a combustion chamber 2, a crank chamber 3, and a scavenging passage 4. The engine 1 includes a piston 5
Are provided so as to be movable up and down. The piston 5 is connected to a crank 7 via a connecting rod 6. Therefore, the configuration is such that the piston 5 moves up and down by the rotation of the crank 7.
The intake port 8 and the exhaust port 9 of the engine 1 are provided with a rotary valve 81 for intake and a rotary valve 91 for exhaust (referred to as rotary valves 81 and 91 for intake and exhaust), respectively. This intake
The through holes 81 are provided in the exhaust rotary valves 81 and 91.
a, 91a are opened, and the through holes 81a, 91a are provided.
When a coincides with the intake / exhaust ports 8 and 9, fresh air is introduced or combustion gas is exhausted.

The intake / exhaust rotary valve 8
1 and 91 are configured to make a half rotation with one rotation of the crank 7. For example, a rotary valve driving chain gear 72 provided on a crankshaft 71 is provided with a rotary valve 81 of an intake rotary valve 81. The first chain gear 82 provided on the shaft, the second chain gear 92 provided on the shaft of the exhaust rotary valve 91 and the chain 10 are linked, and one rotation of the rotary valve driving chain gear 72 makes one rotation. , The first chain gear 82 and the second chain gear 92 make a 1/2 rotation.

In the figure, 11 is a spark plug, 12 is a carburetor, 1
Reference numeral 3 denotes a flywheel. Also, intake and exhaust ports 8,
9, a rotary valve 81 for intake and exhaust provided in
Although the airtightness of 91 is not shown, a seal mechanism is provided.

[0019]

According to a first aspect of the present invention, there is provided an engine in which a piston is provided, an exhaust port is provided on a top surface of a combustion chamber of the engine, an exhaust rotary valve is provided, and a spark plug is provided on a top surface of the combustion chamber. This is a two-stroke engine provided with a scavenging passage communicating the crank chamber and the combustion chamber, and a rotary valve for intake provided in an intake port of the crank chamber. Therefore, it is possible to improve the intake / exhaust and combustion effects efficiently by simplifying the structure or to improve the intake / exhaust / combustion effects.
It is characterized in that the exhaust rotary valve can be operated reliably and smoothly to ensure efficient rotation of the engine.

According to a second aspect of the present invention, there is provided a two-stroke engine having a structure in which the intake and exhaust rotary valves are opened by a half rotation of a crank. Therefore, the rotary valve for intake and exhaust can be operated reliably and smoothly, and the engine can be efficiently rotated.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of the entire engine of the present invention.

FIGS. 2A and 2B are schematic diagrams illustrating the operation of the engine of the present invention. FIG. 2A shows a state in which the piston is before BDC, FIG. 2B shows a state in which the piston is in BDC, and FIG. Indicates that the piston has risen from the bottom dead center, and (d) indicates that the piston is approximately 1
(E) shows the state where the piston has reached the top dead center, and (f) shows the state where the piston has fallen from the top dead center.

FIG. 3 is a schematic view showing a cross section of a part of a rotary valve for intake and exhaust of the present invention.

FIG. 4 is a flowchart illustrating the present invention and conventional exhaust and scavenging.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Combustion chamber 3 Crank chamber 4 Scavenging passage 5 Piston 6 Connecting rod 7 Crank 71 Crank shaft 72 Rotary valve drive chain gear 8 Intake port 81 Intake rotary valve 81a Through hole 82 First chain gear (intake valve chain) 9) Exhaust port 91 Rotary valve for exhaust 91a Through hole 92 Second chain gear (chain gear for exhaust valve) 10 Chain 11 Spark plug 12 Vaporizer 13 Flywheel

Claims (2)

[Claims] An exhaust port provided on a top surface of a combustion chamber of an engine having a piston, a rotary valve for exhaust provided in the exhaust port, a spark plug facing the combustion chamber, A two-stroke engine, comprising: a scavenging passage communicating the crank chamber of the engine with the combustion chamber; and a rotary valve for intake provided in an intake port of the crank chamber. 2. The two-stroke engine according to claim 1, wherein the intake and exhaust rotary valves are opened by a half rotation of a crank.