JPH09203322A - Two cycle engine with supercharger provided with rotary valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to perform supercharging in a two cycle engine in which the supercharging is regarded as difficult to perform, by controlling the valve-opening timing of a rotary valve provided at a cylinder head. SOLUTION: A rotary valve 8 rotating in synchronizm with a main shaft of an engine is provided at a cylinder head 4. After an exhaust passage 6 is opened, the rotary valve 8 is opened to allow the fresh air sent from a supercharger through the inside of the rotary valve 8 and the following valve scavenging passages 10 (10a, 10b), a combustion chamber 3 to flow into a cylinder 1 to scavenge it, and the rotary valve 8 is closed enough later after the exhaust passage 9 is closed. A rotating body 11 having a control part 12 which is in close-contact or in contact with the inner peripheral surface of the shaft of the rotary valve is provided in the shaft of the rotary valve 8. The timing of starting the connection between the inside of the rotary valve 8 and the combustion chamber 3, namely the valve-opening timing of the rotary valve 8 is controlled by turning the control part 12. When supercharging is performed, the valve-opening timing of the rotary valve 8 is delayed in a low speed area, and hastened in a high speed area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-cycle engine with a supercharger equipped with a rotary valve, and to supercharging the engine by controlling the valve opening timing of the rotary valve.

[0002]

2. Description of the Related Art Generally, in a two-cycle engine, the exhaust passage and the scavenging passage are opened on the inner peripheral surface of the cylinder, and the former is closed later than the latter, so that the supercharging pressure escapes and the engine is supercharged. I couldn't do it. Even if the exhaust passage is closed earlier than the scavenging passage by some method, it is difficult to perform supercharging because the boost pressure escapes into the exhaust passage while both are open in the low speed range. It was This tendency was particularly remarkable when a mechanical drive positive displacement supercharger such as a roots type was used as the supercharger.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a wide range from low speed to high speed for a 2-cycle engine in which supercharging is difficult by controlling the valve opening timing of a rotary valve provided in a cylinder head. It is in the place where it is possible to supercharge.

[0004]

In order to solve the drawbacks of the prior art, the present invention provides a cylinder head with a rotary valve that rotates in synchronization with the main shaft of an engine, and opens the rotary valve after the exhaust passage is opened. Then, fresh air is introduced into the cylinder through the internal scavenging passage and the combustion chamber from the shaft of the rotary valve to the scavenging passage and the exhaust passage is closed. In the shaft of the rotary valve,
The rotary body is provided with a control unit that is in close contact with or in contact with the inner peripheral surface of the shaft, and when the control unit is rotated, the communication start timing between the inside of the rotary valve shaft and the combustion chamber, that is, the valve opening timing of the rotary valve. When performing the supercharging by controlling, the valve opening timing of the rotary valve is controlled to be late in the low speed range and early in the high speed range.

[0005]

The cylinder head is provided with a rotary valve, and the supercharging period is set in advance by delaying the closing timing of this rotary valve sufficiently later than that of the exhaust passage. In the shaft of the rotary valve,
A rotating body having a control unit that comes into close contact with or comes into contact with the inner peripheral surface of the shaft is provided, and by controlling the control unit of the rotating body, the start timing of communication between the shaft of the rotary valve and the combustion chamber is controlled.
Control the opening timing of the rotary valve. When supercharging, the valve opening timing of the rotary valve is delayed in the low speed range,
If the optimum control is performed so that the speed becomes faster in the high speed range, it is possible to prevent fresh air from escaping into the exhaust passage, so that supercharging is performed during the supercharging period.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows an embodiment of a two-cycle engine with a supercharger equipped with a rotary valve according to the present invention, in which a rotary valve 8 provided on a cylinder head 4 is a main shaft (crankshaft) of the engine. It rotates synchronously and is driven through the chain and sprocket 5 at a speed ratio of 1: 1 of the rotation of the engine main shaft (1
It is also possible to reduce the speed to / 2 and drive). The rotary valve 8 has rotary sliding surfaces 9 which are arranged so as to face each other. If the rotary sliding surfaces 9 are perpendicular to the axis, the rotary valve 8 has a radial axis due to gas pressure. No load is applied. The combustion chamber 3 is provided with a seal device S that allows fresh air to pass through, and seals the pressure inside the combustion chamber by bringing them into close contact with the rotary sliding surface 9, and the in-valve scavenging ventilation 10 formed in the rotary valve 8 is used. By communicating with the combustion chamber 3, fresh air is allowed to flow into the cylinder 1 through the scavenging passage 7, the shaft of the rotary valve 8 and the combustion chamber 3. As a result, the combustion gas in the cylinder 1 is expelled from the exhaust passage 6, and the scavenging process proceeds. When the exhaust passage 6 is closed as the piston 2 subsequently rises (the rotary valve 8 is also closed thereafter), the charge air in the cylinder 1 is compressed, ignited near the top dead center and burned, and the explosive force is increased. To occur. As a result, when the piston 2 descends and the exhaust passage 6 is opened, the combustion gas in the cylinder 1 is discharged, and the inside of the cylinder 1 is scavenged by the subsequent scavenging process. The sealing device S has a sealing tube a with no abutment.
(The outer circumference has a slight gap with the surrounding wall surface), the seal ring b (the outer circumference is attached to the surrounding wall surface), and the pressing spring c. Special closed-type abutment (known)
It is preferable to use. The rotation sliding surface 9 is lubricated by the oil contained in the fresh air. Next, inside the shaft of the rotary valve 8, there is provided a rotating body 11 having a control unit 12 that comes into close contact with or contacts the inner peripheral surface of the shaft. That is, the control unit 12 of the rotating body is brought into close contact with the inner peripheral surface of the shaft of the rotary valve 8 (giving a minute gap between them), or a slit 16 is formed as shown in FIG. By the action, the inner peripheral surface of the rotary valve 8 is lightly contacted. Although the rotary body 11 does not rotate together with the rotary valve 8, the rotary body 8 is rotated to an arbitrary position to control the valve opening timing of the rotary valve 8. The scavenging passage 7 is connected to a supercharger (generally a positive displacement type such as a roots type, a centrifugal type and further an exhaust turbo type can be considered), and a mixture with air or fuel is pumped. Explaining in detail with the above configuration, the exhaust passage 6 opens at a crank angle of, for example, 50 ° before bottom dead center, closes at 50 ° after bottom dead center, and the rotary valve 8 opens at, for example, 30 ° before bottom dead center ( (Communication between the shaft of the rotary valve 8 and the combustion chamber 3 is started), and the valve is closed (the communication is cut off) at 85 ° after the bottom dead center, and the exhaust passage 6 is closed until the rotary valve 8 is closed. The 35 ° period is set in advance as a supercharging period. In this case, although the exhaust period is as short as 100 °, unlike the conventional case, only the exhaust passage 6 is open in the cylinder 1, so the opening area should be 1.5 to 2 times or more larger. Can give a sufficient angular area. Next, the supercharging of the engine will be described. In the low speed range, the control unit 12 of the rotating body is rotated to the position shown in FIG. As a result, even if the communication between the in-valve scavenging passage 10 and the combustion chamber 3 (seal device S) has already started, the communication between the in-valve scavenging passage 10 and the inside of the shaft of the rotary valve 8 is blocked by the control unit 12. Therefore, the communication between the inside of the shaft of the rotary valve 8 and the combustion chamber 3, that is, the valve opening timing of the rotary valve 8 is delayed, for example, 10 ° after bottom dead center, and blow-through of fresh air is prevented (rotary valve 8 The valve closing time does not change). In this case, the crank angle is 40 ° from the start of scavenging (opening the rotary valve) to closing the exhaust passage, and after the exhaust passage 6 is closed, supercharging is performed during the supercharging period of 35 °.
In the present invention, since fresh air is a uniflow type in which fresh air flows from the combustion chamber 3 side to the exhaust passage 6 side, there is a characteristic that there is essentially little fresh air blow-through. In the medium speed range during supercharging of the engine, the control unit 12 is located in a position further rotated in the right rotation direction, whereby the valve opening timing of the rotary valve 8 is advanced, a sufficient scavenging engine is provided, and supercharging is also efficient. Will be performed. Control unit 1 in the high speed range
2 is set in the range of θ, whereby the valve opening timing of the rotary valve 8 becomes a normal state (30 ° before bottom dead center), and supercharging is efficiently performed. In order to reduce the throttling resistance by the control unit 12 when the communication between the in-valve scavenging passage 10 and the inside of the shaft of the rotary valve 8 is started, it is connected to the rotating body 11 of the in-valve scavenging passage 10 in FIG. The part may be enlarged in the axial direction as shown by the chain double-dashed line. By the way, in FIG. 1B, the in-valve scavenging passage 10 is communicated with the combustion chamber 3 (sealing device S) until the in-valve scavenging passage 10 communicates with the shaft of the rotary valve 8. The fresh air inside may mix with the burnt gas in the combustion chamber 3 and may adversely affect the scavenging action. To prevent this, the fresh air mixed with the burnt gas in the in-valve scavenging passage 10 should be used. It is preferable to reduce the amount by some method, and as shown in FIG. 1C, the in-valve scavenging passage 10 on the downstream side of the rotating body 11 is divided by the separation wall 14 (10a, 10a).
b), and the volume of the portion that does not communicate with the inside of the shaft of the rotary valve 8 while communicating with the combustion chamber 3 in the scavenging passage in the valve is reduced by separating the control portion 12 of the rotating body and the separation wall 14 (valve). It is preferable that the internal scavenging passage 10 be reduced in size from the entire volume to 10a). In this case, in FIG. 1B, even if the in-valve scavenging passage 10 communicates with the shaft of the rotary valve 8, there is throttling resistance by the control unit 12 immediately after, so that the separation wall 14 is the rotary of the combustion chamber 3 as shown in the figure. When approaching the part connected to the valve 8 (the part where the sealing device S is), the scavenging passage 10 in the valve on the delay side of the separation wall 14
It is desirable to form the control unit 12 (to reduce the central angle of the control unit 12) so that b has a sufficiently large communication cross-sectional area and communicates with the inside of the shaft of the rotary valve 8. Further, in this case, when the separation wall 14 passes through a portion of the combustion chamber 3 that is connected to the rotary valve 8 (a portion where the sealing device S is present),
As shown in (a), the scavenging passages 10 in the valve on both sides of the separating wall 14
It is desirable to allow fresh air to flow into the cylinder 1 from a and 10b. In FIG. 1 (c), the scavenging passage 1 in the valve
2 shows the moment when 0a communicates with the combustion chamber 3 (sealing device S).
As shown in (b), the communication between the rotary valve 8 and the shaft is controlled by the control unit 1.
2 blocked). FIG. 1D shows the present invention implemented by a cylindrical rotary valve. The rotary valve 8 is opened after an exhaust passage (not shown) is opened and is closed with a sufficient delay after the exhaust passage is closed. By rotating the control unit 12 of the rotating body, the communication start timing between the inside of the shaft of the rotary valve 8 and the combustion chamber 3 is controlled, and thus the valve opening timing of the rotary valve is controlled. In supercharging, the valve opening timing of the rotary valve 8 is controlled to be late in the low speed range and early in the high speed range.
Also in this case, as described above, as shown in FIG.
The valve exhaust passage on the further downstream side is divided by the separation wall 14 (divided into 10a and 10b) to control the volume of the portion of the valve scavenging passage that does not communicate with the combustion chamber 3 but does not communicate with the shaft of the rotary valve 8. It is desirable to make it small so that it can be made smaller by separating it with the portion 12 and the separating wall 14, and when the separating wall 14 approaches the portion of the combustion chamber 3 connected to the rotary valve 8 (the portion where the sealing device S is located). It is desirable to form the control unit 12 so that the in-valve scavenging passage 10b on the delay side of the separation wall 14 communicates with the inside of the shaft of the rotary valve 8 with a sufficiently large communication cross-sectional area. Further, as shown in FIG. 2D, when the separation wall 14 passes through the portion of the combustion chamber 3 connected to the rotary valve 8 (the portion where the sealing device S is located), the separation wall 1
It is desirable to form the control unit 12 so that fresh air can flow into the cylinder 1 from the in-valve scavenging passages 10a and 10b on both sides of the control valve 4. What carried out the present invention by the spherical rotary valve is shown in FIG. Since this is basically the same as that of the cylindrical rotary valve, the description is omitted. The present invention can be applied not only to the spark ignition engine but also to the compression ignition engine as shown in FIG. 1 (f), and a cylindrical valve is used as the rotary valve 8, for example. Reference numeral 15 is a fuel injection valve, and the piston 2 at the top dead center position is indicated by a chain double-dashed line.
In the present invention, the exhaust passage 6 is preferably opened on the inner peripheral surface of the cylinder 1, but may be formed in the rotary valve 8 itself as shown in FIG. FIG. 2F shows the rotary valve 8 when the rotary valve 8 in FIG. 1C is driven at a speed that is half of the rotation of the engine main shaft. FIG.
(H) is a case where the present invention is applied to a multi-cylinder (for example, two-cylinder) engine, and the rotating body 11 provided in the shaft of the rotary valve 8 of the multi-cylinder is an integral type in which each is integrated. Reference numeral 17 denotes a separating portion, which is formed on the rotating body 11 and separates the inside of the shaft of the rotary valve 8 into spaces for each cylinder. Each space is supplied with fuel from a fuel injection valve or Connecting the vaporizers to each frees you from the problems of fuel distribution. FIG. 3 shows a method for driving the rotating body 11 described with reference to FIGS. 1 and 2. A rotation speed signal obtained from a rotation speed sensor 18 for detecting an engine rotation speed is input to a microcomputer 19 and calculated. An output signal is sent to the servo motor 20. This output signal follows the relationship between the engine rotation speed stored in advance in the microcomputer 19 and the desired amount of rotation of the rotating body 11. The output signal drives the servomotor 20 and causes the engine speed to pass through the worm gear 21. At the time of supply, the rotating body 11 is optimally controlled according to the engine rotation speed. In this case, a signal from an accelerator opening sensor (not shown) may be input to the microcomputer 19 to control the rotating body 11 more finely. In addition, although not particularly shown, the rotating body 1 is provided by a flyweight that rotates together with the main shaft of the engine.
A method of driving 1 is also conceivable.

FIG. 4A shows a rotary valve used for exhaust. The rotary valve 8'opens before the scavenging passage 7'and closes earlier than the exhaust passage 7 '. For example, the rotary valve 8'. Is opened at 80 ° before bottom dead center in the crank angle, closed at 30 ° after bottom dead center, and the scavenging passage 7 ′ is opened at 60 ° before bottom dead center.
It is closed at 60 ° after bottom dead center, and the period of 30 ° from the closing of the rotary valve 8'to the closing of the scavenging passage 7'is a supercharging period. By rotating the control unit 12 'of the rotating body 11' provided in the shaft of the rotary valve 8 ', the valve closing timing of the rotary valve 8' (in the shaft of the rotary valve 8'and in the combustion chamber 3 '
The timing of closing the communication with is controlled, and when performing supercharging, the valve closing timing of the rotary valve 8'is controlled to be early in the low speed range (for example, 20 ° before bottom dead center) and delayed in the high speed range. Of. As a result, fresh air from the scavenging passage 7'does not escape into the shaft of the rotary valve 8 ', so supercharging is performed. Also in this case, as shown in FIG. 4 (b), the in-valve exhaust passage 10 'is divided by the separating wall 14', and when the separating wall 14 'approaches the portion of the combustion chamber 3 connected to the rotary valve 8, the separating wall 14'. It is desirable to form the control portion 12 'so that the in-valve exhaust passage 10'a on the leading side of the valve communicates with the inside of the shaft of the rotary valve 8'with a sufficiently large communication cross-sectional area. When the separation wall 14 'communicates with the portion of the combustion chamber 3 connected to the rotary valve 8', the control portion 12 'is arranged so that exhaust gas can flow out from the valve exhaust passages 10a', 10b 'on both sides of the separation wall 14'. Is desirable.

[0008]

According to the present invention, the valve opening timing (exhaust starting timing) of the rotary valve 8 can be freely controlled by rotating the rotating body 11. Therefore, even if the inside of the cylinder 1 is scavenged, the exhaust passage 6 is newly provided. Without blowing air, the cylinder 1 is pressurized to atmospheric pressure or higher during the period from the closing of the exhaust passage 6 to the closing of the rotary valve 8 to supercharge the two-cycle engine, which has been difficult in the past. I can do things. Therefore, the output and torque of the engine can be increased.

[Brief description of drawings]

FIG. 1 is a diagram of a two-cycle engine with a supercharger equipped with a rotary valve according to the present invention.

FIG. 2 is a diagram showing each embodiment of the present invention.

FIG. 3 is a diagram of an apparatus for driving a rotating body.

FIG. 4 is a diagram of a two-cycle engine with a supercharger equipped with an exhaust rotary valve.

[Explanation of symbols]

1 is a cylinder, 2 is a piston, 3 is a combustion chamber, 4 is a cylinder head, 5 is a sprocket, 6 is an exhaust passage, 7 is a scavenging passage, 8 is a rotary valve, 9 is a rotary sliding surface, 10.1
0a and 10b are scavenging passages in the valve, 11 is a rotating body, 12 is a control unit, 13 is a shaft, 14 is a separation wall, 15 is a fuel injection valve, 1
6 is a slit, 17 is a separating part, 18 is a sensor, 19 is a microcomputer, 20 is a servomotor, 21
Is a warm gear, a is a seal tube, b is a seal ring, and c
Is a pressing spring, 8'is a rotary valve, 10 '・ 10'a ・ 1
Reference numeral 0'b is an in-valve exhaust passage, 11 'is a rotating body, 12' is a control part, 14 'is a separating wall, and 7'is a scavenging passage.

Claims (4)

[Claims] 1. In a two-cycle engine with a supercharger having a scavenging process for expelling burnt gas by fresh air, a cylinder head is equipped with a rotary valve that rotates in synchronization with a main shaft of the engine, and after an exhaust passage is opened. By opening the rotary valve, fresh air sent from the turbocharger through the internal scavenging passage and the combustion chamber from the shaft of the rotary valve to the inside of the rotary valve is introduced into the cylinder to scaveng the burned gas and exhaust it. After the passage is closed, the rotary valve is configured to be sufficiently delayed to close the rotary valve, and further, a rotary body having a control unit in the shaft of the rotary valve, the control unit being in intimate contact with or in contact with the outer peripheral surface of the shaft is provided. By rotating the control unit of the moving body, the timing of starting the communication between the inside of the rotary valve shaft and the combustion chamber is controlled, and thus the valve opening timing of the rotary valve is controlled to supercharge the engine. When the rotary valve is opened A 2-cycle engine with a supercharger equipped with a rotary valve characterized by controlling the period to be slow in the low speed range and fast in the high speed range. 2. A rotator is provided with a volume of a portion of the scavenging passage in the valve downstream of the rotator which is divided by a partition wall and which communicates with the combustion chamber of the scavenging passage in the valve but does not communicate with the shaft of the rotary valve. 2. A two-cycle engine with a supercharger equipped with a rotary valve according to claim 1, wherein the two-cycle engine is constructed so that it can be reduced in size by being separated by a control part and a separating wall. 3. When the separation wall approaches a portion of the combustion chamber where it is connected to the rotary valve, the scavenging passage in the valve on the delay side of the separation wall has a sufficiently large communicating cross-sectional area so that the inside of the shaft of the rotary valve A supercharger-equipped two-cycle engine provided with a rotary valve according to claim 2, wherein a control part of the rotating body is formed so as to communicate with the rotary body. 4. A control part of the rotating body is provided so that fresh air can flow into the cylinder from the in-valve scavenging passages on both sides of the separation wall when the separation wall passes through a portion of the combustion chamber connected to the rotary valve. A two-cycle engine with a supercharger, comprising the formed rotary valve according to claim 3.