JPH0968015A - Rotary valve device for two-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide freedom to set the opening/closing timing of an exhaust passage and a scavenging passage and reduce non-scavenging passing loss of fresh air without causing the lowering of output so as to dissolve uneven combustion peculiar to two cycles and to heighten the rigidity of a cylinder. SOLUTION: A cylinder head 4 is provided with a rotary valve 10 having rotatory-sliding faces 11, 12 disposed in a mutually facing state and fixed firmly and rigidly to a shaft. Sealing means S, S' are provided on the combustion chamber 3 side so as to adhere closely to the rotatory-sliding faces 11, 12. In-valve communicating passages 13, 14 (13', 14') formed at the rotary valve 10 are communicated with the sealing means S, S' with the rotation of the rotary valve 10 rotated synchronously with a main shaft of an engine. In (a), fresh air is thereby made flow in to scavange burnt gas, and in (d), burnt gas in a cylinder 1 is exhausted through the in-valve communicating passages 13', 14'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary valve device for a two-cycle engine, and relates to a rotary valve device for setting the opening / closing timing of a scavenging passage or an exhaust passage and giving a degree of freedom to prevent fresh air from passing through.

[0002]

2. Description of the Related Art Generally, in a two-cycle engine, a scavenging passage and an exhaust passage are open to an inner peripheral surface of a cylinder, and their opening / closing timings are symmetrical with respect to a bottom dead center position (for example, an exhaust passage, The opening time of the scavenging passage is 8 before bottom dead center.
If it is set to 0 ° and 60 °, the closing time will inevitably be 80 ° and 60 ° after bottom dead center, respectively, and it is unavoidable to pass fresh air. To suppress the passage of fresh air, the exhaust passage should be closed as soon as possible, or the scavenging passage should be opened as late as possible. Invite. The higher the output engine, the earlier it was necessary to open the exhaust passage and the scavenging passage. Therefore, a large amount of fresh air was passed, and the fuel efficiency and exhaust gas characteristics were deteriorated.
Further, in the two-cycle engine, a large amount of burned gas is present in the low load region, uncomfortable irregular combustion is accompanied, and the exhaust passage and the scavenging passage reduce the rigidity of the cylinder.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a degree of freedom in setting the opening and closing timings of the exhaust passage and the scavenging passage to reduce the fresh air passing loss without lowering the output, and to reduce the two-cycle cycle. It is intended to provide a structure capable of eliminating the irregular combustion peculiar to the engine and increasing the rigidity of the cylinder.

[0004]

SUMMARY OF THE INVENTION In order to solve the drawbacks of the prior art, the present invention provides a rotary valve having a rotary sliding surface which is disposed so as to face each other and is fixed rigidly and rigidly to each shaft. The head is equipped with sealing means on the combustion chamber side so as to be in close contact with the respective rotary sliding surfaces to seal the pressure inside the combustion chamber, and the rotary valve is rotated in accordance with the rotation of the rotary valve rotating in synchronization with the main shaft of the engine. By connecting the formed in-valve communication passages to the respective sealing means, fresh air is introduced into the cylinder through the respective in-valve communication passages to scavenge burned gas, or The burned gas is configured to be discharged through each of the valve communication passages.

[0005]

The valve provided on the cylinder head is synchronously driven by the main shaft of the engine through a chain, a sprocket and the like. Since the combustion chamber side is provided with the sealing means that is in close contact with the rotary sliding surfaces of the rotary valve, the pressure inside the combustion chamber is reliably sealed. Further, by connecting the in-valve communication passages formed in the rotary valve to the respective sealing means, fresh air can be introduced into the cylinder through the respective in-valve communication passages to scavenge burned gas. Alternatively, the burnt gas in the cylinder is configured to be discharged through each of the valve communication passages. The opening / closing timing of the rotary valve can be freely set regardless of the piston position. Therefore, the opening / closing timing of the exhaust passage or the scavenging passage can be asymmetrical with respect to the bottom dead center, and the exhaust passage can be closed early or the scavenging passage can be closed without reducing the exhaust period or the scavenging period. Since it can be opened late, the fresh air is blocked.
Further, in the present invention, the flow at the time of scavenging is a uniflow type in one direction, so the fuel distribution in the combustion chamber is uneven, and it is possible to greatly improve the ignitability by placing the spark plug in the portion where much fuel is distributed. it can. Further, in the present invention, since the exhaust passage or the scavenging passage is moved to the cylinder head side, the rigidity of the cylinder becomes extremely high.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a rotary valve device for a two-cycle engine according to the present invention. First, in FIG. 1 (a), the rotary valves 10 provided on the cylinder head 4 are arranged so that they face each other. It has moving surfaces 11 and 12, and is rigidly and rigidly fixed to the shaft (the rotary sliding surfaces 11 and 12 are perpendicular to the axis in the figure). 1 is a cylinder, 2 is a piston, and a rotary valve 1
0 is, for example, a chain depending on the main shaft (crank shaft) of the engine,
It is driven through the sprocket 5 and rotates in synchronization with the main shaft of the engine. Reference numerals 6 and 7 denote bearings (rolling bearings) that support the rotary valve 10 and include oil seals. The rotary valve 10 is normally supported by bearings 6 and 7, but when the rotary sliding surfaces 11 and 12 are perpendicular to the axis as shown in the figure, the rotary valve 10 is not subjected to a radial load due to the gas pressure in the combustion chamber. Therefore, the inner wall surface of the cylinder head 4 surrounding the rotary valve 10 and the outer periphery of the shaft may be supported as a plain bearing. The cylinder head 4 is a rotary valve 10
Due to the assembling, the line is divided by the line AA '. The combustion chamber 3 side is provided with sealing means S, S'for passing fresh air, and the pressure inside the combustion chamber is sealed by bringing them into close contact with the rotary sliding surfaces 11, 12 and is formed in the rotary valve 10. By connecting the in-valve communication passages 13 and 14 to the sealing means S and S'respectively (opening the scavenging passage 9), fresh air is allowed to flow into the cylinder 1 via the in-valve communication passages 13 and 14. . In order to make it easy to understand, FIG. 1B shows a schematic view of the rotary valve 10 when viewed from the axial direction (the figure shows the rotary valve 10 at 1 / th of rotation of the engine main shaft).
This is an example of driving by decelerating to 2, but in the case of 1/1 constant speed driving, it becomes as shown in FIG. At this time, the fresh air that has passed through the sealing means S and S ′ merges with each other and heads into the cylinder 1 (thickens the flow) to enhance the scavenging efficiency. When the fresh air thus flows into the cylinder 1, the burnt gas in the cylinder 1 is expelled from the exhaust passage 8 (opening on the inner peripheral surface of the cylinder before the drawing), and the scavenging process is completed. When the exhaust passage 8 is closed as the piston 2 subsequently rises (the communication between the sealing means S, S'and the in-valve communication passages 13, 14 is also cut off), the fresh air in the cylinder 1 is compressed and top dead. Around the point, the ignition plug ignites and burns to generate an explosive force. When the piston 2 descends and the exhaust passage 8 is opened by this, the combustion gas in the cylinder 1 is discharged, and the above-mentioned scavenging process causes the above-mentioned scavenging. Thus, the inside of the cylinder 1 is scavenged. The fresh air supplied into the cylinder 1 is introduced into a crank chamber (not shown) from a vaporizer or the like via a reed valve, and the scavenging passage 9
Through the valve communication passages 13 and 14. The fresh air supplied to the cylinder 1 needs to be pre-pressurized, and a crank chamber is normally used. However, when a scavenging pump (roots type or the like) is separately provided, the scavenging passage 9 is used for this scavenging pump. Make them connect. By the above, each rotation explosive force is obtained. Next, the sealing means S (S ') is a seal body 15 (15') and a seal ring 16 (16 ') having no abutment.
And a spring 17 for pressing these against the rotary sliding surface 11 (12)
(17 ') and the sealing means S
If the axial play of (S ') is made small, the pressure in the combustion chamber rises and it easily comes into close contact with the rotary sliding surface 11 (12).
The spring 17 (17 ') is unnecessary. Seal ring 16
For (16 '), it is desirable (known) to use a hermetically-sealed abutment having a special abutment as shown in FIG. 2 (a) or (b), and its outer periphery is a correspondingly processed wall surface. It sticks. Further, the seal body 15 (15 ') is the rotary sliding surface 1
Since it is necessary to properly follow and closely adhere to the surface runout of 1 (12) and the like, a slight gap is provided between the outer circumference and the corresponding wall surface. The sealing means S is shown in FIG.
As shown in FIG. 2D, the seal body 15 and the diaphragm seal 18 may be used and the elastic force of the diaphragm seal 18 may bring the seal body 15 into close contact with the rotary sliding surface 11 for sealing. A seal ring 19 may be fitted on the outer circumference of the above to closely contact the rotary sliding surface 11 for sealing. The seal body 15 is rotated and slidable by the gas pressure while sufficiently securing the strength, that is, the wall thickness of the seal body 15.
In order to reduce the pressing force applied to the seal body 15, it is conceivable to chamfer the seal body 15 as shown in FIG. 2 (e) (because the effective pressure receiving area of the seal body 15 is reduced by the amount corresponding to the chamfer). If necessary, the seal body 15 may be formed with a collar 20 as shown in FIG. By the way, the seal body 15
Since the rotary valve 10 also tries to rotate itself by the rotation of the rotary valve 10, a protrusion 21 may be formed as shown in FIG. The above also applies to the sealing means S '. The lubrication between the seal means S (S ') and the rotary sliding surface 11 (12) is performed by the lubrication oil contained in the fresh air in the two-cycle engine because the lubrication oil is generally contained therein.

Although the rotary valve 10 is used for scavenging in FIG. 1A, it can be used for exhausting as shown in FIG. That is, in FIG. 1D, the rotary valve 10
Is rotated in synchronization with the main shaft of the engine (decelerated to 1/2 in the figure to be driven), and when the pressure in the combustion chamber is sufficiently expanded as the piston 2 descends, the in-valve communication passage 13 'formed in the rotary valve 10 is 14 'communicates with the sealing means S, S'respectively (opens the exhaust passage 8'), discharges the burned gas in the cylinder 1 through the in-valve communication passages 13 ', 14', and scavenges by the subsequent scavenging process. The burned gas is further expelled by the fresh air flowing in from the passage 9'through the valve communication passages 13 'and 14', so that the burned gas is scavenged. When the communication between the in-valve communication passages 13 ', 14' and the sealing means S, S'is cut off as the piston 2 rises (the scavenging passage 9'is also closed), the fresh air in the cylinder 1 is compressed, The piston 2 is ignited and burned near the top dead center to generate an explosive force. Thus, the piston 2 is pushed down. The sealing means S, S'provided on the combustion chamber 3 side so as to be in close contact with the rotary sliding surfaces 11, 12 have the structure described above, but in order to avoid heat damage from the burnt gas discharged, It is desirable to prepare outside the passage.
In this case, if the sealing means S and S ′ are made of a material having a high thermal conductivity such as an Al alloy or a copper alloy, the temperature of each part is lowered,
The compression ratio can be increased. Lubrication between the sealing means S, S'and the rotary sliding surfaces 11, 12 is performed by supplying lubricating oil from a metering pump (not shown) which is metered according to the load. To

FIG. 3 shows various embodiments of the present invention. First, FIG. 3 (a) raises the scavenging passage 9 in FIG. 1 (a) to a high position, and the valve is passed through rotary sliding surfaces 11 and 12. The internal communication passages 13 and 14 are contacted.
In this case, the seal ring 22 is attached to the rotary sliding surface 1 as shown in the drawing.
If it is prepared so as to be in close contact with
Since 14 does not become a calculation element of the crank chamber compression ratio,
A high compression ratio can be adopted. FIG. 3 (B) shows that the scavenging passage 9 independently branched from the crank chamber is connected to the in-valve communication passages 13 and 14, and FIG. 3 (C) shows scavenging into the shaft of the rotary valve 10. The passage 9 is connected. In addition, in FIG. 3B, the scavenging passage 9 may be connected to the end surface of the rotary valve 10 as shown by a chain double-dashed line (a seal ring 22 similar to that in FIG. 3A can be used). Next, FIG. 4 (a) shows the scavenging passage 9 in FIG. 1 (a).
In addition, the throttle valve 23 is provided with a throttle valve 23. When the scavenging passage 9 is throttled by the throttle valve 23, the scavenging is performed slowly, so that the passage of fresh air is completely suppressed.
The throttle valve 23 is controlled according to the operating conditions such as the load of the engine and the rotation speed. For example, the throttle valve 23 is driven by a driving device 24 as shown by an accelerator pedal or a two-dot chain line. For example, a diaphragm device is used as the drive device 24. When the opening degree of the accelerator pedal or the engine rotation speed exceeds a certain value (which should be taken out as an electric signal), the pressure in the crank chamber is introduced to open the throttle valve 23. (These are well-known techniques and will not be described in detail). In any case, the throttle valve 23 must be fully opened in the high load and high speed rotation range.
As described above, the throttle valve 23 completely prevents the fresh air from passing through in the high load / low speed region as well as in the low load region. In the present invention, the rotary sliding surfaces 11 and 12 may have a conical surface shape as shown in FIG. 4B (further, a spherical shape is also conceivable), but the fresh air passing through the sealing means S and S ′ are mutually It is necessary to configure so as to merge (to thicken the flow) toward the inside of the cylinder 1 so as to obtain high scavenging efficiency. In this case, the radial load received by the rotary valve 10 is the rotary sliding surface 11, Since it appears as a component force corresponding to the tilt angle of 12, it is smaller than the cylindrical type and has less friction loss (if the rotary sliding surfaces 11 and 12 are perpendicular to the axis as shown in FIG. Radial load is not received in principle).
In both FIG. 4B and FIG. 1A, it is desirable that the outer diameters of the sealing means S and S'be equal to each other so that thrust is not applied to the rotary valve 10. In FIG. 4 (c), the distance between the sealing means S and S'is increased to about the diameter of the cylinder 1, and the fresh air passing through the sealing means S and S'collides and merges with each other, resulting in an extremely thick flow. Then, it goes to the cylinder 1.

[0009]

According to the present invention, since the cylinder head 4 is provided with the rotary valve 10, the opening / closing timing of the exhaust passage and the scavenging passage can be freely set regardless of the piston position. Therefore, the exhaust passage can be closed early or the scavenging passage can be opened late without reducing the exhaust period or the scavenging period, so that the fresh air passing loss is greatly reduced. Further, as described with reference to FIG. 4A, by providing the throttle valve 23 in the scavenging passage 9, it is possible to completely prevent fresh air from passing through.
Further, in the present invention, the flow at the time of scavenging is a one-way uniflow type, so the fuel distribution in the combustion chamber 3 is biased, and the spark plug is placed in the portion where a large amount of fuel is distributed (Fig. 1 (d)).
Then, it is arranged so as to be as close as possible to the top surface of the piston at the top dead center position.) It is possible to greatly improve ignitability and eliminate irregular combustion. In addition, in the present invention, since either the scavenging passage or the exhaust passage is moved to the cylinder head side, the rigidity of the cylinder 1 is significantly increased, the life of the piston ring and the like is extended, and the inner peripheral surface of the cylinder 1 is opened. There is an advantage that the opening area of the scavenging passage or the exhaust passage can be made sufficiently large. As described above, the friction loss of the rotary valve 10 according to the present invention is small.

[Brief description of drawings]

FIG. 1 is a diagram showing a rotary valve device for a two-cycle engine according to the present invention.

FIG. 2 is a view showing a sealing means.

FIG. 3 is a diagram of various embodiments according to the present invention.

FIG. 4 is a diagram of various embodiments according to the present invention.

[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 and 7 are bearings, 8 is an exhaust passage, 8 is an exhaust passage, 9 is a scavenging passage, 9'is a scavenging passage, 10 is a rotary valve, 11 and 12 are rotary sliding surfaces, 1
3 and 14 are communication passages in the valve, 15 and 15 'are seal bodies, 16
・ 16 'is a seal ring, 17 ・ 17' is a spring, S ・
S'is sealing means, 13 'and 14' are in-valve communication passages, 18
Is a diaphragm seal, 19 is a seal ring, 20 is a collar, 21 is a protrusion, 22 is a seal ring, 23 is a throttle valve, and 24 is a drive device.

Claims (4)

[Claims] 1. A two-cycle engine in which explosive force for each rotation is obtained by a scavenging process for expelling burnt gas by fresh air. The two-cycle engines are arranged so as to face each other and are fixed to each shaft firmly and rigidly. The cylinder head is provided with a rotary valve having a surface, and further, a sealing means is provided on each combustion chamber side so as to be in close contact with each of the rotary sliding surfaces to seal the pressure in the combustion chamber, and fresh air passing through the sealing means is provided. By merging with each other and heading into the cylinder, the in-valve communication passages formed in the rotary valve communicate with the respective sealing means in accordance with the rotation of the rotary valve that rotates in synchronization with the main shaft of the engine. A two-cycle engine is characterized in that fresh air is introduced into the cylinder through each of the valve communication passages to scavenge burned gas in the cylinder. Tari valve device. 2. A two-cycle engine in which explosive force of each rotation is obtained by a scavenging process of expelling burnt gas by fresh air, the rotary slides being arranged to face each other and fixed rigidly and rigidly to respective shafts. A rotary valve having a rotary valve having a surface is provided on the cylinder head, and further, a sealing means is provided on each combustion chamber side so as to be in close contact with each rotary sliding surface to seal the pressure in the combustion chamber and rotate in synchronization with the main shaft of the engine. In accordance with the rotation of, the in-valve communication passages formed in the rotary valve communicate with the respective sealing means to discharge the burnt gas in the cylinder through the respective in-valve communication passages, and by the subsequent scavenging process. A rotary valve device for a two-cycle engine, further characterized in that burned gas is expelled by fresh air through each of the valve communication passages. 3. The rotary valve device for a two-cycle engine according to claim 1 or 2, wherein the rotary sliding surfaces arranged so as to face each other are perpendicular to the axis. 4. A scavenging passage communicating with the in-valve communication passage is provided with a throttle valve, and the throttle valve is controlled according to the operating state of the engine to reduce the fresh air passing loss. Rotary valve device for 2-cycle engine.