JPH09242570A - Spark ignition type two-stroke internal combustion engine with combustion control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim at the combustion of the fresh air inside of a combustion chamber by self-ignition, namely, to aim at the combustion in the active thermal atmosphere at the time of low-load operation. SOLUTION: In a spark ignition type two-stroke internal combustion engine with combustion control device, which control the area of an inlet of an exhaust passage or the area of an opening of a passage inside of the exhaust passage by driving an exhaust control valve in response to the internal combustion engine speed or the open degree of a throttle valve and which burns the fresh air inside of the combustion chamber with self-ignition at the time of low-load operation, combustion chamber volume adjusting means 19, 20 for increasing and decreasing the volume of a combustion chamber 16 in response to the operation condition of the internal combustion engine 1 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark ignition type two-stroke internal combustion engine with a combustion control device, which is designed to cause fresh air in a combustion chamber to perform self-ignition combustion, that is, to perform active heat atmosphere combustion at least during low load operation. is there.

[0002]

2. Description of the Related Art In a conventional spark ignition type two-stroke internal combustion engine, an exhaust passage and a scavenging passage which are opened and closed by a piston are formed in an inner peripheral surface of a cylinder hole, and fresh air prepressed in a crank chamber is scavenging passage. Is supplied to the combustion chamber at the top of the cylinder hole, the burnt gas in the combustion chamber is discharged from the exhaust passage to the exhaust passage, and the fresh air compressed in the combustion chamber is ignited by the spark plug. It was

In such a conventional spark ignition type two-stroke internal combustion engine, when the exhaust passage is made thicker in order to set the output and efficiency in the high speed and high load operation region to a high level or more,
In the low load operation range, the amount of unburned hydrocarbons in the exhaust gas increased due to blow-through of fresh air and unstable combustion, and fuel consumption deteriorated.

In order to solve this, the exhaust control valve is driven at an exhaust opening ratio according to the internal combustion engine speed and the throttle valve opening degree, so that at least in the low load operation range.
Properly control the pressure in the combustion chamber when the exhaust opening is blocked by the piston, activate the fresh air in the combustion chamber by the thermal energy of the burnt gas remaining in the combustion chamber, and refresh the combustion chamber at the desired ignition timing for operating the internal combustion engine. The applicant has applied for the development of an internal combustion engine capable of self-igniting air (Japanese Patent Application Laid-Open No. 7-71279).

[0005]

In the spark ignition type two-stroke internal combustion engine with the combustion control device, when the throttle valve opening is small such as in the idling operation range, even if the exhaust control valve is throttled, Even if an attempt is made to self-ignite the fresh air by increasing the temperature of the burnt gas by increasing the residual amount of burnt gas burned in the combustion chamber, if the throttle valve is throttled, Correspondingly, the amount of combustion supply is small, and the fresh air containing the residual burned gas in the combustion chamber may not reach the self-ignition temperature, and the fresh air may not be self-ignited.

In an attempt to improve this, when the stroke volume is kept constant and the volume of the combustion chamber is decreased to increase the apparent compression ratio and increase the temperature of the combustion chamber near the top dead center, a high load is applied. Knocking is likely to occur during operation, which is not suitable for practical use.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a spark ignition type 2 with a combustion control device which overcomes the above problems.
According to the improvement of the stroke internal combustion engine, the exhaust control valve is driven to control the exhaust passage inlet or the passage opening area in the exhaust passage in accordance with at least the internal combustion engine speed or the throttle valve opening degree, and at least during low load operation. A spark-ignition two-stroke internal combustion engine with a combustion control device for burning fresh air in a combustion chamber by self-ignition, comprising combustion chamber volume adjusting means for increasing or decreasing the volume of the combustion chamber according to the operating condition of the internal combustion engine. It is characterized by that.

Since the present invention is constructed as described above, during low load operation in which the throttle valve is throttled and the supply air amount and combustion supply amount are small, particularly during idling operation,
By reducing the volume of the combustion chamber by the combustion chamber volume adjusting means and increasing the compression ratio, fresh air containing residual burned gas in the combustion chamber is strongly adiabatically compressed,
The fresh air in the combustion chamber is self-ignited and can be burned in an active heat atmosphere, so that the emission of unburned hydrocarbons is suppressed and the fuel consumption is improved.

Further, according to the present invention, in a normal operating state in which the throttle valve is opened, particularly in a high load low speed operating state where knocking is likely to occur, the combustion chamber volume is increased by the combustion chamber volume adjusting means to reduce the compression ratio. By doing so, knocking can be avoided, and quiet and fuel-efficient driving can be performed.

As described above, according to the present invention, it is possible to improve the fuel consumption and suppress the emission of unburned hydrocarbons by expanding the active heat atmosphere combustion region while avoiding knocking.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention shown in FIGS. 1 and 2 will be described below. Spark ignition type two-stroke internal combustion engine 1 equipped with the combustion control device of the present invention
Is mounted on a motorcycle (not shown). In the spark ignition type two-stroke internal combustion engine 1, a cylinder block 3 and a cylinder head 4 are provided above the crankcase 2.
Are sequentially overlapped and are integrally connected to each other, and the throttle valve opening and the internal combustion engine speed during no-load operation have characteristics as shown by Z curves in FIGS. 5 and 6. There is.

A piston 6 is vertically slidably fitted in a cylinder hole 5 formed in the cylinder block 3, and the piston 6 and the crankshaft 8 are connected to each other by a connecting rod 7. The crankshaft 8 is driven to rotate in association with the elevation of the.

Further, the crank chamber 9 in the crankcase 2
Is formed in the intake passage 10, a carburetor (not shown) and a reed valve 11 are provided in series in the intake passage 10, and a scavenging port 12 is opened in the inner peripheral surface of the cylinder hole 5 and An exhaust port 13 is opened above the port 12, and the scavenging port 12 communicates with the crank chamber 9 through a scavenging passage 14, and the exhaust port 13 communicates with an exhaust passage 15.

Furthermore, the combustion chamber 16 above the cylinder hole 5
A spark plug 17 is provided at the top of the, and the fresh air mixed with the fuel by a carburetor (not shown) is sucked into the crank chamber 9 having a negative pressure in the ascending stroke through the reed valve 11 and in the descending stroke. When the piston 6 descends and the scavenging port 12 is opened while being compressed, the compressed fresh air is discharged from the scavenging passage 14 into the combustion chamber.
Part of the burned gas in the combustion chamber 16 supplied to the inside of the combustion chamber 16 is discharged from the exhaust port 13 into the exhaust passage 15 by the introduction of the compressed fresh air, and the scavenging port 12 and then the exhaust port 13 due to the rise of the piston 6. Is closed, the air-fuel mixture in the combustion chamber 16 is compressed by the rise of the piston 6, and self-ignition is performed near the top dead center by the thermal energy of the spark plug 17 or the residual gas of the previous cycle. .

Further, a cylindrical recess 18 which is adjacent to the spark plug 17 and communicates with the combustion chamber 16 is formed in the cylinder head 4, and a rotary valve body 19 is rotatably fitted in the cylindrical recess 18 and the rotary valve A recess 20 is formed in the body 19, and the rotary valve body 19
Is a sensor (not shown) that is connected to a movable piece (not shown) of a solenoid via a lever (not shown) and detects the rotational speed of the spark ignition two-stroke internal combustion engine 1 and the opening of a throttle valve (not shown). Is provided,
A computer that receives both of these detection signals and performs the following operations is provided, and as shown in FIG.
When the engine speed of the spark ignition two-stroke internal combustion engine 1 is less than 5000 rpm and the throttle valve opening is less than 8% in the operating region A, the solenoid is turned on and, as shown in FIG. The recess 20 of the valve body 19 is sealed and cut off from the combustion chamber 16, the volume of the combustion chamber 16 is reduced, and the combustion chamber 16 is reduced.
When the apparent compression ratio of 16 is set to about 8 and the operating region B other than the operating region A of FIG. 7 is used, the solenoid is not turned on, and the rotary valve body 19 is turned on as shown in FIG.
The recess 20 is communicated with the combustion chamber 16 through the opening 21, the volume of the combustion chamber 16 is expanded, and the apparent compression ratio of the combustion chamber 16 is approximately 6
Is set to

In the spark ignition type two-stroke internal combustion engine 1, when the recess 20 of the rotary valve body 19 is communicated with the combustion chamber 16 through the opening 21 and the apparent compression ratio is set to about 6, the activation is activated. The hot atmosphere combustion region X is within the range shown in FIG. 5, and the recess 20 of the rotary valve body 19 is the combustion chamber.
When the apparent compression ratio is set to about 8 by cutting off against 16, the active-heat atmosphere combustion region Y has the characteristic of being enlarged in FIG.

In addition, when the ignition switch is cut off in the operating state of the spark ignition type two-stroke internal combustion engine 1, the exhaust control valve 24 is opened upward or the solenoid is turned off so that the apparent appearance of the combustion chamber 16 is reduced. The compression ratio is set to 6, or the throttle valve is throttled further than the idle throttle opening of 5%.

Further, a valve body accommodating recess 22 is formed above the exhaust passage 15, and a shaft 23 penetrating the cylinder block 3 parallel to the crankshaft 8 is provided downstream of the valve body accommodating recess 22.
The base portion of the exhaust control valve 24 is pivotally supported by the vertical swingable.

Furthermore, a flat elongated hole 25 is formed at the tip of the exhaust control valve 24 along the flat surface of the exhaust control valve 24, and is rotatable on both sides of the exhaust passage 15 about an axis parallel to the crankshaft 8. The rotary body 26 is fitted to the rotary shaft 26, and both ends of the connecting shaft 27 loosely fitted in the flat elongated hole 25 of the exhaust control valve 24 are the rotary body 26.
It is eccentrically attached to 26 and is integrally fitted.

Moreover, the rotating body 26 is connected to a governor (not shown) which operates by detecting the rotational speed of the crankshaft 8, and when the rotational speed of the crankshaft 8 is low, as shown in FIG. The exhaust control valve 24 swings downward, and when the rotational speed of the crankshaft 8 is high, the rotating body 26 rotates counterclockwise, and the exhaust control valve 24 moves upward as shown in FIG. It is designed to oscillate (the rotation control of the rotating body 26 does not depend on the governor,
The rotor 26 is rotated by an exhaust control servomotor controlled by a CPU control signal that receives input signals such as the rotation speed of the crankshaft 8, the throttle valve opening, and the supply pressure, and calculates based on a required control map. It may be controlled).

The embodiment illustrated in FIGS. 1 and 2 is
Since it is configured as described above, the following operation is performed. That is, at the time of start-up, the engine is in a no-load operation state, so a throttle valve (not shown) is opened, and the engine speed increases along the Z curve of FIGS. 5 and 6 as the opening degree increases. Since the opening degree of is less than 8%, the engine speed is less than 5000 rotations, the recess 20 of the rotary valve body 19 is blocked from the combustion chamber 16, and the exhaust control valve 24 is tilted downward. The apparent compression ratio is switched to 8 by the volume reduction of the combustion chamber 16, and the closing timing of the exhaust port 13 in the ascending stroke of the piston 6 is advanced.
As a result of advancing the opening start timing of the exhaust port 13 in the descending stroke of the piston 6, even if the combustion chamber 16 is at a low temperature, the fresh air is heated to a sufficiently high temperature by the large adiabatic compression due to the high compression ratio and activated Combustion in a hot atmosphere is promoted, emission of unburned hydrocarbons is suppressed, and combustion is improved.

Further, in a normal operating state in which a throttle valve (not shown) is opened by 8% or more, a high load operating state, or a high-speed operating state in which the engine speed exceeds 5000 rpm, FIG.
As shown in FIG. 4, the exhaust control valve 24 is tilted upward, and the recess 20 of the rotary valve body 19 is communicated with the combustion chamber 16 through the opening 21, so that the volume of the combustion chamber 16 is expanded. The opening start timing of the exhaust port 13 in the ascending stroke of the piston 6 is delayed, and the opening start timing of the exhaust port 13 in the descending stroke of the piston 6 is advanced.
Since the apparent compression ratio is maintained at a low level by the volume increase of 16, a large amount of gas exchange can be smoothly performed without causing knocking, and it is possible to increase the output quietly.

As described above, in the conventional two-stroke internal combustion engine, in the vicinity of the idle set point where the throttle opening is reduced to about 5%, the two-stroke internal combustion engine with an apparent compression ratio of 6 performs active heat atmosphere combustion. However, in the embodiment shown in FIGS. 1 and 2, the rotary valve body 19 has a large amount of unburned hydrocarbons and is liable to cause irregular combustion, as shown in FIG. And the apparent compression ratio is increased to 8, the active heat atmosphere combustion region is expanded from the range shown in FIG. 5 to the range shown in FIG. 6, so that the active heat atmosphere combustion can be performed. In addition to improving fuel efficiency, stable driving conditions can be obtained.

In the embodiment shown in FIGS. 1 and 2, the apparent compression ratio is changed stepwise by providing a plurality of rotary valve elements 19 each having a different volume of the recess 20 and selectively opening and closing them. be able to.

In the embodiment shown in FIGS. 1 and 2, the rotation of the rotary valve body 19 increases or decreases the combustion chamber 16, but as shown in FIG. 3, the recess 28 communicating with the combustion chamber 16 is used. May be formed in the cylinder head 4, and a shutter valve 30 that is opened and closed by a valve opening / closing drive means such as a solenoid (not shown) may be provided in the opening 29 of the recess 28. In the embodiment shown in FIG. The same effects as those of the illustrated embodiment can be obtained.

A combustion controller may be constructed as shown in FIG. That is, a sub cylinder hole 31 communicating with the cylinder hole 5 is formed in the cylinder head 4, a sub piston 32 is slidably fitted in the sub cylinder hole 31, and an outer end of the sub cylinder hole 31 is covered with a lid 33. The pressure chamber 34 may be sealed to form a hydraulic chamber 34, and pressure oil may be supplied to and discharged from the hydraulic chamber 34 to increase or decrease the volume of the sub chamber 35 of the sub cylinder hole 31, and thus the volume of the combustion chamber 16. In this embodiment, the apparent compression ratio can be continuously changed in addition to the effect similar to that of the above embodiment.

[Brief description of drawings]

FIG. 1 is a longitudinal side view of an embodiment of a spark ignition two-stroke internal combustion engine with a combustion control device in a normal operating state according to the present invention.

FIG. 2 is a vertical sectional side view in a low load / low speed operation state in the embodiment of FIG.

FIG. 3 is a vertical cross-sectional side view of a main part of another embodiment.

FIG. 4 is a vertical sectional side view of a main part of still another embodiment.

5 is a characteristic diagram illustrating a boundary between an active heat atmosphere combustion region and a normal combustion region when the rotary valve is opened in a low load / low speed operation state in the embodiment illustrated in FIGS. 1 and 2. FIG.

FIG. 6 is a characteristic diagram illustrating a boundary between an active heat atmosphere combustion region and a normal combustion region when the rotary valve is closed in the embodiment illustrated in FIGS. 1 and 2.

FIG. 7 is a control diagram illustrating a situation of switching a rotary valve in the embodiment illustrated in FIGS. 1 and 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spark ignition type 2-stroke internal combustion engine, 2 ... Crankcase, 3 ... Cylinder block, 4 ... Cylinder head, 5
... Cylinder bore, 6 ... Piston, 7 ... Connecting rod, 8 ... Crankshaft, 9 ... Crank chamber, 10 ... Intake passage, 11 ... Reed valve, 12 ... Scavenging port, 13 ... Exhaust port, 14 ... Scavenging passage, 15 ... Exhaust passage, 16 combustion chamber, 17 spark plug, 18 ...
Cylindrical recess, 19 ... Rotary valve body, 20 ... Recess, 21 ... Opening,
22 ... Valve body accommodating recess, 23 ... Shaft, 24 ... Exhaust control valve, 25 ... Flat elongated hole, 26 ... Rotating body, 27 ... Connecting shaft, 28 ... Recess, 29 ... Opening,
30 shutter valve, 31 ... sub cylinder hole, 32 ... sub piston,
33 ... Lid, 34 ... Hydraulic chamber, 35 ... Sub chamber.

Claims (6)

[Claims] 1. An exhaust control valve is driven to control an exhaust passage inlet or a passage opening area in the exhaust passage in accordance with at least an internal combustion engine rotational speed or a throttle valve opening degree, and at least during low-load operation, the inside of the combustion chamber is controlled. A spark ignition type two-stroke internal combustion engine with a combustion control device for burning fresh air by self-ignition, comprising combustion chamber volume adjusting means for increasing or decreasing the volume of the combustion chamber according to the operating condition of the internal combustion engine. A characteristic spark ignition stroke internal combustion engine. 2. An exhaust control valve is driven to control an exhaust passage inlet or a passage opening area in the exhaust passage in accordance with at least an internal combustion engine speed or a throttle valve opening degree, and at least during low-load operation, the inside of the combustion chamber is controlled. In a spark ignition type two-stroke internal combustion engine with a combustion control device that burns fresh air by self-ignition, the self-ignition timing can be adjusted by increasing or decreasing the volume of the combustion chamber according to the operating condition of the internal combustion engine. A spark ignition type two-stroke internal combustion engine characterized in that 3. The exhaust control valve is driven in accordance with at least the internal combustion engine speed or the throttle valve opening to control the exhaust passage inlet or the passage opening area within the exhaust passage, and at least during low load operation, the inside of the combustion chamber is controlled. In a spark ignition type two-stroke internal combustion engine with a combustion control device for burning fresh air by self-ignition, at least one auxiliary combustion chamber communicating with the main combustion chamber, outside the main combustion chamber at the top of the cylinder, The main combustion chamber and the auxiliary combustion chamber are provided with an opening / closing means that can be opened / closed, and the self-ignition timing can be adjusted by opening / closing the opening / closing means according to the operating condition of the internal combustion engine. A spark ignition type two-stroke internal combustion engine. 4. At least one sub-combustion chamber communicating with the main combustion chamber and an opening / closing means provided to open and close the main combustion chamber and the sub-combustion chamber, outside the main combustion chamber at the top of the cylinder. The spark ignition type two-stroke internal combustion engine according to claim 1 or 2, characterized in that it is provided. 5. The opening / closing means of claim 3 is constituted by at least one rotary valve communicating with the main combustion chamber at the top of the cylinder, and the internal space of the rotary valve body of the rotary valve comprises the opening / closing means of claim 3. The spark ignition type two-stroke internal combustion engine according to claim 3, wherein a sub combustion chamber is formed. 6. The spark ignition type two-stroke internal combustion engine according to claim 3, wherein the opening / closing means according to claim 3 is a poppet valve or a shutter valve.