JP4153643B2 - Layered scavenging two-cycle engine and disc valve device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a crankcase compression type stratified scavenging two-cycle engine, and more particularly, to an air-leading stratified scavenging two-cycle engine configured to perform pre-scavenging using scavenging air and a disk valve of the two-cycle engine.
[0002]
[Prior art]
  In a conventional two-cycle engine, when the piston moves to the top dead center, the crank chamber formed in the crankcase becomes negative pressure, and the air-fuel mixture is sucked into the crank chamber, and the piston is lowered. When moving in the direction of the dead center, the air-fuel mixture compressed in the crank chamber is introduced from the crank chamber into the combustion chamber when the scavenging port is opened, and is filled into the combustion chamber while pushing out the combustion gas. In this scavenging stroke, since the open sections of the scavenging port and the exhaust port overlap in a wide range, about 30% of the air-fuel mixture is blown out together with the combustion gas, which is an excessive amount of THC (total hydrocarbons). ) This is the main cause of emissions and waste of fuel.
[0003]
  In order to reduce the blow-through of the air-fuel mixture, an air-leading laminar scavenging method is provided. In such a scavenging system, the air-fuel mixture is filled into the crank chamber during the intake stroke toward the top dead center, and at the same time, air is sucked into the crank chamber through the scavenging passage connected to the scavenging port and then filled into the scavenging passage. When the scavenging port opens during the combustion and exhaust stroke, the air in the scavenging passage is introduced into the combustion chamber prior to the air-fuel mixture, scavenging the combustion exhaust gas, and then the air-fuel mixture burns. It is introduced indoors. In such a scavenging system, the blow-through of the air-fuel mixture is greatly reduced to about one third of that of the conventional engine.
[0004]
  Japanese Laid-Open Patent Application No. 10-252565 discloses a structure in which a fuel control valve of a carburetor and an air control valve are integrated with respect to such an air lead type stratified scavenging two-cycle engine.
[0005]
  In the air-driven stratified scavenging engine according to the prior art, the passage for supplying the leading air introduced from the air control valve to the cylinder and the crank chamber is branched downstream from the air control valve to the same number (2 to 3) as the scavenging ports. And, it is connected to the scavenging port passage of the cylinder with a tube such as rubber, and is configured to lead to a passage provided in the cylinder and the crankcase through a reed valve provided in each scavenging passage.
[0006]
  The air introduced from the air control valve is once sucked into the crank chamber during the cylinder compression stroke of the piston, and leads the scavenged air from the scavenging port into the combustion chamber during the scavenging of the piston downward stroke.
[0007]
  In addition, in the conventional technique proposed in Japanese Patent Laid-Open No. 7-139358, an air passage that opens at a position close to the scavenging port is provided in the scavenging passage, a check valve is provided in the air passage, and the air passage is further provided in the air passage. A control valve is provided, and the control valve is interlocked with the throttle operation of the engine. In such an engine, when the piston moves up, the crank chamber becomes negative pressure, and the air-fuel mixture is sucked into the crank chamber from the air-fuel mixture supply port, and at the same time, air is sucked by opening the check valve from the air passage. Air enters all or part of the passage. Next, when the scavenging port is opened during the lowering of the piston in the combustion and exhaust strokes, air is first jetted into the combustion chamber, and then the air-fuel mixture is supplied.
[0008]
  In such prior art, air is supplied from the scavenging port earlier into the combustion chamber and scavenged early in the scavenging process so as to reduce the blow-through of the air-fuel mixture to the exhaust port, and is slightly delayed from this scavenging air. Supply means for feeding the air-fuel mixture in the crank chamber from the scavenging port into the combustion chamber is provided.
[0009]
[Problems to be solved by the invention]
  Such an air-leading stratified scavenging two-cycle engine can reduce the amount of air-fuel mixture blown off with the combustion gas, eliminate excessive THC (total hydrocarbons) emission, and suppress waste of fuel.
  However, in the air leading type stratified scavenging two-cycle engine proposed in Japanese Patent Laid-Open No. 10-252565, the structure of the leading air passage is provided with the same number of rubber tubes and reed valves as the scavenging ports. It has a structure. For this reason, the number of parts is large, the number of assembly steps is increased, and the cost is increased. In addition, since such an air passage pipe is provided outside the cylinder, the axial dimension of the engine is increased.
[0010]
  Also, in a two-cycle engine, during low load operation including idling operation, the amount of air is suppressed to stabilize combustion as a rich mixture ratio, and during high load operation, a relatively thin mixture ratio is used to reduce fuel consumption and exhaust gas. However, in the prior art proposed in Japanese Patent Application Laid-Open No. 7-139358, the flow rate of air supplied from the air supply passage during the scavenging action depends on the engine operation. It is not controlled to respond appropriately to the condition.
[0011]
  For this reason, the air amount tends to increase during low load operation including idling operation, so it is difficult to stabilize the combustion as a rich mixture ratio by limiting the air amount, and harmful in exhaust gas during high load operation. It is difficult to operate in such a way as to reduce the fuel consumption rate while maintaining a low mixing ratio so as to reduce unnecessary emissions.
[0012]
  In view of the problems of the prior art, the first aspect of the present invention is to simplify the structure of the scavenging passage of the stratified scavenging two-cycle engine, reduce the size and weight of the engine, reduce the number of parts and the number of assembly steps, and reduce the manufacturing cost. The purpose.
[0013]
[0014]
  Also,By using a disc valve that is opened and closed by the crank web, the timing of starting and ending the intake of the scavenging leading air is optimized to improve combustion and reduce harmful emissions in the exhaust gas.2The purpose.
[0015]
[Means for Solving the Problems]
  In order to solve such a problem, the present invention provides, as an invention according to claim 1, an exhaust port and a scavenging port provided on the side of the cylinder, and an intake port that opens when the piston rises and supplies air-fuel mixture into the crank chamber. In the air-leading stratified scavenging two-cycle engine having a scavenging passage connected to the scavenging port and an air supply port for supplying scavenging air from an air cleaner to the scavenging passage, the scavenging passage is connected to the air supply port. An air passage and an air-fuel mixture passage communicating with the intake port are provided in parallel inside the air passage, and the air that is provided on the connection portion side of the air passage of the insulator to the scavenging passage and is directed to the scavenging passage side And a scavenging passage that is provided in walls on both sides of the crankcase and that forms a pair that opens into the crank chamber. The scavenging passage on the crankcase side connected to the part is connected to the left and right branch passages formed in the walls on both sides of the cylinder and connected to the scavenging port at one end. An air supply passage provided on the outlet side of the check valve and a left and right air branch passage connecting the left and right scavenging branch passages are formed in the wall of the section.An opening end face of the scavenging passage opening of the crankcase is formed at an end face perpendicular to the crank shaft center, and a minute gap is formed between the end face perpendicular to the crank shaft center of the crank web of the crank shaft and the open end face. Forming a disc valve in which the area of the scavenging passage opening is changed by rotation of the crank web, and the shape of the scavenging passage opening is formed by the crank web according to the rotation of the crank web. It is formed so as to gradually widen along the rotation direction of the crank web so that the area to be opened becomes large.A stratified scavenging two-cycle engine is proposed.
  According to a second aspect of the present invention, an exhaust port and a scavenging port are provided on the side of the cylinder, connected to the scavenging port, and an intake port that opens when the piston rises to supply air-fuel mixture into the crank chamber. In an air lead type stratified scavenging two-cycle engine having a scavenging passage and an air supply port for supplying scavenging air from an air cleaner to the scavenging passage, the air passage is connected to the air supply port and communicates with the intake port An air-fuel mixture passage arranged in parallel inside, and a check that is provided on the connection portion side of the air passage of the insulator to the scavenging passage and allows only the air flow toward the scavenging passage The scavenging passage is provided in a wall on both sides of the crankcase, and is connected to a pair of scavenging passage openings that open to the crank chamber. In the scavenging passage on the gas side, left and right branch passages are formed in the walls on both sides of the cylinder and one end is connected to the scavenging port, and further, in the walls on both sides of the cylinder An air supply passage provided on the outlet side of the check valve and a left and right air branch passage connecting the left and right scavenging branch passages are formed, and an opening end face of the scavenging passage opening of the crankcase is formed. The scavenging passage is formed on an end surface perpendicular to the crank shaft center, and a minute gap is formed between the end surface perpendicular to the crank shaft center of the crank web of the crank shaft and the open end surface. The disc valve is configured to change the area of the opening, and the scavenging passage opening is opened in an arc shape having substantially the same width along the rotation direction of the crank web, and further from the opening. Extend in the direction of rotation proposes a stratified scavenging two-cycle engine and characterized by having a large opening area as a whole have the cutout portion recessed to the open end face.
[0016]
  Claims 1 and 2According to this invention, since the scavenging passage is formed in a pair in the side wall of the crankcase and the side wall of the cylinder, it becomes a scavenging passage having a long length, and the air filled in the long scavenging passage As a result of the leading scavenging action, the air-fuel mixture is supplied after the air scavenging action is sufficiently performed, and the air blow-through of the air-fuel mixture is suppressed.
[0017]
  Further, since all the scavenging passages and air passages are formed in the crankcase and the cylinder, the external piping for forming the air passage and its accessory parts are not required, the number of parts is reduced and the number of assembly steps is reduced. .
[0018]
  Claim6The invention described in claim 1Or 2The scavenging branch passages and the air branch passages formed on both sides of the cylinder are surrounded by substantially parallel passage walls in the same direction.
[0019]
  According to this invention, since the passage walls of the scavenging and air branch passages are formed integrally and substantially in parallel with the cylinder, the slide mold of the cylinder mold can be integrated with the mold structure. Can be simplified and the manufacturing cost of the mold can be reduced.
[0020]
  Claim1, 2The described invention,in frontThe opening end surface of the scavenging passage opening of the crankcase is formed at an end surface perpendicular to the crank shaft center, and a minute gap is formed between the end surface perpendicular to the crank shaft center of the crank web of the crank shaft and the open end surface. The disk valve is formed so that the area of the scavenging passage opening is changed by the rotation of the crank web.
[0021]
  TakeConstitutionAccording to the present invention, the disc valve is formed by the crankcase scavenging passage opening and the crank web that are open in the crank chamber, reduce the gap between the side surface of the crankcase and the crank web, and open to the crank chamber. Therefore, the scavenging air blowing speed from the scavenging port can be suppressed, and the amount of air-fuel mixture caught in the exhaust gas can be further reduced.
[0022]
  Also, by opening / closing the scavenging passage opening of the disc valve, after the scavenging port is opened, the scavenging passage opening is opened to delay the scavenging start timing, and before the scavenging port is closed, the scavenging passage opening is closed to advance the scavenging end timing. Therefore, the scavenging timing can be optimized while maintaining the shape and size of the scavenging port at the optimum values.
[0023]
  And claims1Described inventionBeforeThe scavenging passage opening is opened by the crank web as the crank web rotates.mouthIt is formed to expand in the rotation direction so that the area to be formed becomes large.
[0024]
  According to this invention, the opening area of the scavenging passage opening gradually increases with the rotation of the crank web, thereby suppressing the scavenging speed flowing from the opening through the scavenging passage into the combustion chamber from the scavenging port. By doing so, the amount of air-fuel mixture caught in the exhaust gas is reduced, and blow-through of the air-fuel mixture can be suppressed.
[0025]
  Claim2Described inventionBeforeThe scavenging passage opening is not opened in an arc shape having substantially the same width in the rotation direction of the crank web.Furthermore, it has a notch part extending in the counter-rotating direction from the opening and having the opening end face recessed, and has a large opening area as a whole.
[0026]
  According to this invention, the volume ratio in the crank chamber of the disc valve increases, and the compression rate is improved.
[0027]
  Claim3The described invention is claimed.1,2, the disk valve is configured to be able to control the start and end timings of the scavenging air (leading air) to the cylinder according to the opening and closing timing of the scavenging passage opening.
[0028]
  According to such an invention, it is difficult to control the amount and timing of the leading air when the leading air is sucked by the negative pressure of the crank chamber as in the prior art. By controlling the start and end timing of the intake of air into the cylinder, it is possible to control the amount of leading air and the intake timing, thereby reducing unburned hydrocarbons in the exhaust gas and reducing the fuel consumption rate.
[0029]
  Claim4, 5The described invention relates to an invention of a disc valve device that is applied to a piston valve type two-cycle engine in addition to the air-leading stratified scavenging two-cycle engine,The invention according to claim 4An exhaust port and a scavenging port are provided on the side of the cylinder, and includes an intake port that opens when the piston rises and supplies an air-fuel mixture into the crank chamber, and a scavenging passage connected to the scavenging port. A scavenging passage on the crankcase side provided in a wall on both sides of the crankcase and connected to a pair of scavenging passage openings opening in the crank chamber is formed in a wall on both sides of the cylinder. In the two-cycle engine formed by connecting the left and right branch passages, one end of which is connected to the scavenging port, the opening end surface of the scavenging passage opening of the crankcase is formed as an end surface perpendicular to the crankshaft center, A minute gap is formed between an end surface of the crank web of the crank shaft perpendicular to the crank shaft center and the open end surface, and the scavenging passage is opened by rotation of the crank web. Configure the disk valve area parts is made to change, the disc valve, the opening and closing timing of the scavenging passage opening is capable of controlling the suction start and end timing to the scavenging of the cylinder,The shape of the scavenging passage opening is formed so as to gradually widen along the rotation direction of the crank web so that the area opened by the crank web increases as the crank web rotates. BecomeIt is in the disk valve apparatus of the stratified scavenging two-cycle engine characterized by this.
  According to a fifth aspect of the present invention, an exhaust port and a scavenging port are provided on the side of the cylinder, connected to the scavenging port, and an intake port that opens when the piston rises and supplies an air-fuel mixture into the crank chamber. A scavenging passage, and the scavenging passage is provided in a wall on both sides of the crankcase and connected to a scavenging passage opening that forms a pair that opens into the crank chamber. In the two-cycle engine formed in the walls on both sides of the cylinder and connected to the left and right branch passages, one end of which is connected to the scavenging port, the opening end surface of the scavenging passage opening of the crankcase is cranked. The crank web is formed on an end face perpendicular to the shaft center, and a minute gap is formed between the end face perpendicular to the crank shaft center of the crank web of the crankshaft and the open end face. The disc valve is configured such that the area of the scavenging passage opening is changed by rotation, and the disc valve is configured to be able to control the start and end timing of the scavenging of the scavenging gas to the cylinder according to the opening / closing timing of the scavenging passage opening. The scavenging passage opening is opened in an arc shape having substantially the same width in the rotation direction of the crank web, and further has a notch that extends from the opening in the counter-rotation direction and has the opening end face recessed. The disk valve device of a stratified scavenging two-cycle engine is characterized by having a large opening area as a whole.
[0030]
  Claims 4 and 5Also in such an invention, the claims1, 2Similar to the described invention, it is possible to reduce unburned hydrocarbons in the exhaust gas and reduce the fuel consumption rate.
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. Absent.
[0038]
  FIG. 1 shows the present invention.The fruitFIG. 2 is a perspective view showing a structure of a scavenging passage and an air passage provided in the cylinder and the crankcase, FIG. Figure 32FIG. 4 is an explanatory view showing the relationship between the crank web and the scavenging passage in the first embodiment of the disc valve, and FIG. 5 is a cross-sectional view taken along line AA of FIG. Figure6FIG. 4 is a view corresponding to FIG. 4, showing a second embodiment of the disk valve.7FIG. 6 is a view corresponding to FIG. 5 (a cross-sectional view taken along line AA in FIG. 1).
[0039]
  1 to 5, 2 is a cylinder, 4 is a piston, 6 is a crankshaft, 6 a is a crank web constituting the crankshaft 6, 5 is a crankcase, and 3 is a connecting connecting the piston 4 and the crankshaft 6. A rod, 7 is a cylinder head, 8 is a spark plug, 11 is an air cleaner, and 12 is a vaporizer. Reference numeral 25 denotes a combustion chamber, 5a denotes a crank chamber formed inside the crankcase 5, and 15b and 15 denote air-fuel mixture passages connecting the carburetor 12 and the crank chamber 5a. Reference numeral 13 a denotes an exhaust port opened at the side of the cylinder 2 and connected to the exhaust pipe 13.
[0040]
  Reference numeral 9a denotes scavenging ports provided on the left and right sides of the exhaust port 13a of the cylinder 2 so as to face two portions substantially perpendicular to the exhaust port 13a. As shown in FIG. 2, each of the scavenging ports 9a forming a pair includes a scavenging branch passage 109e that forms a pair in the cylinder 2 in an oblique direction, and a pair of scavenging passages 109f that is a confluence of the scavenging passages. The crankcase 5 communicates with the crank chamber 5a through a pair of scavenging passages 109d formed in an arc shape in the walls on both sides of the crankcase 5 and paired scavenging passage openings 109b and 109b.
[0041]
  As shown in FIG. 5, the scavenging passage openings 109b and 109b can be opened and closed by the crank web 6a of the crankshaft 6, and in the direction of the crankshaft 60 as shown in FIG. The end face 6d of the web 6a is close to each other with a minute gap, and the end face 6d of the crank web 6a constitutes a disc valve that controls opening and closing of the openings 109b and 109b. Further, as shown in FIG. 4, the scavenging passage openings 109b and 109b are gradually increased in opening area by the crank web 6a with respect to the rotational direction N of the crankshaft 6 in the direction perpendicular to the crankshaft 60. In order to open, the width of the side opened first by the crank web 6a is small, and it is formed in a tapered shape in the lower part gradually becoming wider.
[0042]
  Figure6-7Shows a second embodiment of the disk valve. In this embodiment, the scavenging passage opening 109b is concentric with the crank chamber 5a and opened in an arc shape having substantially the same width in the rotation direction of the crank web 6a.
The opening 109b is7As shown in FIG. 5, the cutout portion 109c extending in the counter-rotating direction from the communicating portion to the scavenging passage 109d is formed, and an opening portion having a large opening area as a whole is formed.
[0043]
  Reference numeral 10 denotes an air supply chamber provided inside the side portion of the cylinder 2. The upstream side is connected to an air passage 10b in an insulator 30, which will be described later, and the downstream side is connected to a pair of air branch passages 10a. As shown in FIG. 2, the air branch passage 10a communicates with a pair of scavenging passages 109f and a pair of scavenging branch passages 109e.
  The air supply chamber 10 is provided with a check valve 16 that allows only the flow toward the air branch passages 10a and 10a at the openings to the left and right air branch passages 10a and 10a.
[0044]
  As shown in FIGS. 2 to 3, the paired air branch passages 10 a and 10 a and the scavenging branch passage 109 e are formed by a passage wall 109 h protruding integrally with the cylinder 2 from the side of the cylinder 2. 109i is formed substantially symmetrically with respect to the cylinder center axis 50. The two passage walls 109h and 109i are formed in parallel to each other so that the integral mold can be pulled out from the cylinder 2 side to the side.
[0045]
  Reference numeral 30 denotes an insulator for thermally shutting off the engine body side and the intake system, and the insulator 30 is bolted to the side surface of the cylinder 2. The air passage 10b is formed on the upper side of the insulator 30, and the air-fuel mixture passage 15b is formed on the lower side.
  The upstream side of the mixture passage 15b communicates with a throttle valve 14 for controlling the mixture flow rate in the carburetor 12, and the downstream side communicates with the crank chamber 5a via an intake port 15a.
  Reference numeral 110 denotes an air passage pipe integrated with the carburetor 12 that connects the air cleaner 11 and the insulator 30. The air passage pipe 110 is provided with an air control valve 20 that changes the air passage area. The throttle valve 14 of the vaporizer 12 is interlocked with the throttle valve 14.
[0046]
  When the air-leading stratified scavenging two-cycle engine having such a configuration is operated, when the piston 4 is lowered by the combustion pressure in the combustion chamber 25 and the exhaust port 13a is opened as shown in FIG. The combustion gas (exhaust gas) is discharged to the exhaust pipe 13 through the exhaust port 13a, and discharged to the outside air through a muffler (not shown).
  When the piston 4 is further lowered, the left and right scavenging ports 9a, 9a are opened, and the air stored in the scavenging branch passage 109e flows into the combustion chamber 25 as shown by the arrows in FIG. Push to the exhaust port 13a side.
[0047]
  Next, the air-fuel mixture accumulated in the crank chamber 5a passes through the scavenging passage openings 109b and 109b, the scavenging passages 109d and 109d, and the scavenging branch passages 109e and 109e, respectively, and passes through the scavenging ports 9a and 9a to the combustion chamber 25. Flows in.
  When the piston 4 is lowered and is at the bottom dead center as shown in FIG. 3, the exhaust port 13a, the two scavenging ports 9a, 9a are open, and supply of air and air-fuel mixture into the combustion chamber 25 is performed. Is or is about to exit. When the piston 4 rises from the bottom dead center, the scavenging ports 9a and 9a are closed by the piston 4 and the inside of the crank chamber 5a becomes a sealed space, and expansion, that is, a pressure drop starts.
[0048]
  When the piston 4 is further raised, the exhaust port 13a is closed, and the compression of the mixed gas in the combustion chamber 25 starts, while the pressure in the crank chamber 5a further decreases due to the increase in the volume of the crank chamber 5a due to the rise of the piston 4. . As shown in FIG. 2, when the piston 4 is further raised, an intake port 15a formed on the side surface of the cylinder 2 opens, and an air-fuel mixture generated by the carburetor 12 and controlled in flow rate by the throttle valve 14 is indicated by an arrow in FIG. As described above, the air-fuel mixture passages 15b and 15 are supplied into the crank chamber 5a through the intake port 15a.
[0049]
  The pressure drop in the crank chamber 5a is also transmitted to the left and right air branch passages 10a and 10a via the scavenging passage openings 109b and 109b, the scavenging passages 109d and 109d, and the scavenging branch passages 109e and 109e. 16 opens, and the air supplied into the air supply chamber 10 through the check valve 16 by the action described later flows into the crank chamber 5a.
[0050]
  Here, the scavenging branch passages 109e and 109e, the scavenging passages 109f and 109f, and the scavenging passages 109d and 109d, which form a pair from the scavenging ports 9a and 9a to the crank chamber 5a, have a length as shown in FIG. Since a long scavenging passage is formed, the air supplied to the scavenging passage is filled in such a long scavenging passage.
[0051]
  When the piston 4 reaches the vicinity of the compression top dead center, a spark is discharged into the combustion chamber 25 by the spark plug 8, and the compressed air-fuel mixture is ignited and burned. Due to this combustion, the piston 4 is pushed down by the generated pressure, and rotational torque is generated in the crankshaft 6.
[0052]
  When the piston 4 descends and the exhaust port 13a opens, the combustion gas in the combustion chamber 25 flows from the exhaust port 13a to the exhaust pipe 13, and then is discharged to the outside through a muffler (not shown).
  On the other hand, as the piston 4 descends, the gas in the crank chamber 5 a is compressed on the back side of the piston 4. When the piston 4 is further lowered and the side scavenging ports 9a and 9a are opened, the air-fuel mixture supplied into the crank chamber 5a as described above forms a pair of scavenging passage openings 109b and 109b, The scavenging passages 109d and 109d, the scavenging passages 109f and 109f, and the scavenging branch passages 109e and 109e are blown into the combustion chamber 25 from the scavenging ports 9a and 9a, and the combustion gas (exhaust gas) in the combustion chamber 25 is exhausted. The scavenging action of pushing out from the port 13a is performed.
[0053]
  During the scavenging action, the check valves 16 are opened as described above, so that the scavenging passages 109d and 109d, the scavenging passages 109f and 109f, and the scavenging branch passages 109e and 109e are initially filled with air. Therefore, within a certain period from the start of the scavenging action, the scavenging action is performed by the air from the scavenging ports 9a, 9a into the combustion chamber 25, and then the air-fuel mixture in the crank chamber 5a becomes the scavenging passages 109d, 109f, scavenging. The scavenging ports 9a and 9a are blown into the combustion chamber 25 through the branch passage 109e.
  The above process is repeated to operate the engine and generate power.
[0054]
  In such an air lead type stratified scavenging two-cycle engine, as shown in FIGS. 1 to 3, scavenging passages 109 d and 109 d provided in the crankcase 5 are provided symmetrically with respect to the cylinder center axis 50 on both side surfaces of the crankcase 5. The scavenging passage openings 109b and 109b are also opened to the crank chamber 5a symmetrically with respect to the cylinder central axis 50.
[0055]
  Then, as shown in FIG. 5, the clearance between the end surface 109g of the opening 109b and the end surface 6d of the crank web 6a is reduced so that the scavenging passage openings 109b and 109b on the crankcase 5 side and the crank webs 6a and 6a A disk valve is formed. FIG. 4 shows a state where the scavenging passage opening 6b is gradually opened by the rotational position of the crank web 6a in the crank chamber 5a. By changing the position of the scavenging passage openings 109b and 109b along the rotation direction N of the crankshaft 6, and by changing the timing of the scavenging blowout from the scavenging ports 9a and 9a, further, as shown in FIG. As described above, the shape of the scavenging passage openings 109b and 109b is tapered so that the opening area gradually increases when the crank webs 6a and 6a rotate, thereby reducing the scavenging speed from the exhaust gas. It is possible to further reduce the amount of air-fuel mixture involved in the gas.
[0056]
  In addition, the scavenging passage openings 109b and 109b are opened after the scavenging ports 9a and 9a are opened to delay the scavenging start timing, and the scavenging passage openings 109b and 109b are closed before the scavenging ports 9a and 9a are closed. As a result, the scavenging timing can be optimized while maintaining the shape and size of the scavenging ports 9a, 9a at the optimum values.
[0057]
  Further, the disk valve can control the start and end timings of the leading air (scavenging air) to the cylinder 2 by the opening and closing timing of the scavenging passage openings 109b and 109b.
  That is, it is possible to control the start timing of the leading air intake by the timing when the crank webs 6a, 6a open the scavenging passage openings 109b, 109b, and the end timing of the scavenging air intake by the closing timing. .
[0058]
  However, when the leading air is sucked by the negative pressure of the crank chamber as in the prior art, the amount and leading timing of the leading air are difficult to control. Since the start and end timing of intake into the cylinder 2 can be controlled, the amount of leading air and the intake timing can be controlled, and unburned hydrocarbons in the exhaust gas can be reduced and the fuel consumption rate can be reduced.
[0059]
  If the disc valve is configured as in the first embodiment shown in FIGS. 4 to 5, the opening areas of the scavenging passage openings 109b and 109b gradually increase as the crank web crank webs 6a and 6a rotate. Thus, by controlling the scavenging speed that flows out from the openings 109b and 109b through the scavenging passages 109d and 109d into the combustion chamber 25 from the scavenging ports 9a and 9a, Decrease.
[0060]
  Also, the disc valve6-7If the disk valve is configured as shown in the second embodiment, the disk valve forms an opening having a large opening area as a whole, so that the volume ratio of the disk valve in the crank chamber 5a increases and compression is performed. The rate is improved.
[0061]
  Further, in the air-leading stratified scavenging two-cycle engine according to the embodiment, an air branch passage 10a provided in the cylinder 2 and a scavenging branch passage 109e to the scavenging port 9a of the cylinder 2 are shown in FIG. Since the structure is surrounded by parallel passage walls 109h and 109i in the same direction, the slide mold of the cylinder mold can be integrated, thereby simplifying the mold structure and reducing the manufacturing cost. can do.
[0062]
[0063]
[0064]
[0065]
[0066]
[0067]
[0068]
[0069]
[0070]
[0071]
[0072]
[0073]
[0074]
[0075]
[0076]
[0077]
[0078]
[0079]
[0080]
【The invention's effect】
  As described above, according to the present invention, since all the scavenging passages and air passages are formed in the crankcase and in the cylinder, the external piping for air passage formation and its accessory parts are not required, and the number of parts is reduced. The number of assembly steps can be reduced, and the engine can be reduced in weight and size.
[0081]
  In addition, since the scavenging passages are formed in pairs in the side wall of the crankcase and the side wall of the cylinder, the scavenging passage becomes a long length, and the leading scavenging action is caused by the air filled in the long scavenging passage. Therefore, the air-fuel mixture is supplied after the scavenging action by the air is sufficiently performed, and the blow-through of the air-fuel mixture is suppressed, and the waste of fuel can be reduced.
[0082]
  Also, in the present inventionAccording to this, the openings of the scavenging passages provided on both side surfaces of the crankcase are opened in the crank chamber, and the gap between the side surface of the crankcase and the crank web is made small so that the disc between the crankcase opening and the crank web Since the valve is formed, there is an effect of suppressing the scavenging air blowing speed from the scavenging port and further reducing the amount of air-fuel mixture caught in the exhaust gas.
[0083]
  Also, by opening / closing the scavenging passage opening of the disc valve, after the scavenging port is opened, the scavenging passage opening is opened to delay the scavenging start timing, and before the scavenging port is closed, the scavenging passage opening is closed to advance the scavenging end timing. Therefore, the scavenging timing can be optimized while maintaining the shape and size of the scavenging port at the optimum values.
[0084]
  Claims3With this configuration, by controlling the start and end timing of leading air to the cylinder with the disc valve, it becomes possible to control the amount of leading air and the suction timing, thereby reducing unburned hydrocarbons in the exhaust gas. In addition, the fuel consumption rate can be reduced.
[0085]
  Further claims6According to the invention, since the air branch passage provided in the cylinder and the branch passage to the scavenging port are surrounded by substantially parallel passage walls in the same direction, this scavenging passage portion of the die-cast mold of the cylinder is provided. The slide mold can be integrated, the mold structure can be simplified, and the manufacturing cost can be reduced.
[0086]
[0087]
[0088]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view perpendicular to a crankshaft center including a cylinder central axis of a stratified scavenging two-cycle engine according to a first embodiment of the present invention.The
FIG. 2 is a perspective view showing the arrangement of scavenging passages and air passages in the first embodiment of the present invention.
FIG. 3 is a view corresponding to FIG. 2 for explaining the operation in the first embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a relationship between a crank web and a scavenging passage in the first example of the disc valve in the first embodiment of the present invention.
FIG. 5 is a cross-sectional view taken along line AA in FIG.
[Fig. 6]FIG. 6 is a view corresponding to FIG. 4 showing a second embodiment of the disk valve.
[Fig. 7]FIG. 6 is a view corresponding to FIG. 5 in the second embodiment (a cross-sectional view taken along line AA in FIG. 1).
[Explanation of symbols]
  2 cylinders
  3 Connecting rod
  4 Piston
  5 Crankcase
  5a Crank chamber
  6 Crankshaft
  6a Crank web
  6d Crank web end face
  7 Cylinder head
  8 Spark plug
  9a Scavenging port
  10 Air supply chamber
  10a Air branch passage
  10e Gas passage
  11 Air cleaner
  12 Vaporizer
  13 Exhaust pipe
  13a Exhaust port
  14 Throttle valve
  15, 15b Mixture passage
  15a Inlet
  16 Check valve
  20 Air control valve
  25 Combustion chamber
  30 InsleyT
  50 Cylinder center axis
  60 Crankshaft center
  109b Scavenging passage opening
  109c Notch
  109d, 109f Scavenging passage
  109e Scavenging branch passage
  109g Opening end face
  109h, 109i passage wall
  110 Air passagetube

Claims (6)

An exhaust port and a scavenging port are provided on the cylinder side, an intake port that opens when the piston rises and supplies air-fuel mixture into the crank chamber, a scavenging passage connected to the scavenging port, and an air cleaner to the scavenging passage In an air lead type stratified scavenging two-cycle engine having an air supply port for supplying scavenging air of
An air passage connected to the air supply port and an air-fuel mixture passage communicating with the air intake port are provided inside the insulator, and the air passage of the insulator is provided on the connection side to the scavenging passage. And a check valve that allows only the flow of air toward the scavenging passage, and the scavenging passages are provided in the walls on both sides of the crankcase and form a pair of scavenging openings in the crank chamber. A scavenging passage on the crankcase side connected to the passage opening is connected to left and right branch passages formed in walls on both sides of the cylinder and connected to the scavenging port at one end, and further to the cylinder The air supply passages provided on the outlet side of the check valve and the left and right air branch passages connecting the left and right scavenging branch passages are formed in the walls on both sides of the check valve, and the scavenging of the crankcase Passage open An opening end surface of the portion is formed on an end surface perpendicular to the crank shaft center, and a minute gap is formed between the end surface perpendicular to the crank shaft center of the crank web of the crank shaft and the opening end surface, The disc valve is configured such that the area of the scavenging passage opening is changed by the rotation, and the shape of the scavenging passage opening is increased by the crank web according to the rotation of the crank web. A stratified scavenging two-cycle engine characterized by being formed so as to be gradually widened along the rotation direction of the crank web . An exhaust port and a scavenging port are provided on the cylinder side, an intake port that opens when the piston rises and supplies air-fuel mixture into the crank chamber, a scavenging passage connected to the scavenging port, and an air cleaner to the scavenging passage In an air lead type stratified scavenging two-cycle engine having an air supply port for supplying scavenging air of
An air passage connected to the air supply port and an air-fuel mixture passage communicating with the air intake port are provided inside the insulator, and the air passage of the insulator is provided on the connection side to the scavenging passage. And a check valve that allows only the flow of air toward the scavenging passage, and the scavenging passages are provided in the walls on both sides of the crankcase and form a pair of scavenging openings in the crank chamber. A scavenging passage on the crankcase side connected to the passage opening is connected to left and right branch passages formed in walls on both sides of the cylinder and connected to the scavenging port at one end, and further to the cylinder The air supply passages provided on the outlet side of the check valve and the left and right air branch passages connecting the left and right scavenging branch passages are formed in the walls on both sides of the check valve, and the scavenging of the crankcase Passage open An opening end surface of the portion is formed on an end surface perpendicular to the crank shaft center, and a minute gap is formed between the end surface perpendicular to the crank shaft center of the crank web of the crank shaft and the opening end surface, The disc valve is configured such that the area of the scavenging passage opening is changed by the rotation, the scavenging passage opening is opened in an arc shape having substantially the same width along the rotation direction of the crank web, and A stratified scavenging two-stroke cycle engine having a large opening area as a whole, having a cutout portion extending in a counter-rotating direction from the opening and having the opening end face recessed . 3. The disk valve is configured to be able to control start and end timings of the scavenging air (leading air) to the cylinder according to opening and closing timing of the scavenging passage opening. stratified scavenging two-cycle engine. An exhaust port and a scavenging port are provided on the side of the cylinder, and includes an intake port that opens when the piston rises and supplies an air-fuel mixture into the crank chamber, and a scavenging passage connected to the scavenging port. A scavenging passage on the crankcase side provided in a wall on both sides of the crankcase and connected to a pair of scavenging passage openings opening in the crank chamber is formed in a wall on both sides of the cylinder. In a two-cycle engine formed by connecting left and right branch passages, one end of which is connected to the scavenging port,
An opening end surface of the scavenging passage opening of the crankcase is formed at an end surface perpendicular to the crank shaft center, and a minute gap is formed between the end surface perpendicular to the crank shaft center of the crank web of the crank shaft and the opening end surface. Then, a disk valve is configured in which the area of the scavenging passage opening is changed by rotation of the crank web, and the disc valve starts and starts the suction of the scavenging into the cylinder according to the opening and closing timing of the scavenging passage opening. The end timing is configured to be controllable, and the shape of the scavenging passage opening gradually becomes wider along the rotation direction of the crank web so that the area opened by the crank web increases as the crank web rotates. A disk valve device for a stratified scavenging two-cycle engine, wherein the disk valve device is formed so as to expand . An exhaust port and a scavenging port are provided on the side of the cylinder, and includes an intake port that opens when the piston rises and supplies an air-fuel mixture into the crank chamber, and a scavenging passage connected to the scavenging port. A scavenging passage on the crankcase side that is provided in a wall on both sides of the crankcase and is connected to a pair of scavenging passage openings that open to the crank chamber is formed in a wall on both sides of the cylinder. In a two-cycle engine formed by connecting left and right branch passages, one end of which is connected to the scavenging port,
An opening end face of the scavenging passage opening of the crankcase is formed on an end face perpendicular to the crankshaft center, and a minute gap is formed between the end face perpendicular to the crankshaft center of the crank web of the crankshaft and the opening end face. Then, a disk valve is configured in which the area of the scavenging passage opening is changed by rotation of the crank web, and the disc valve starts and starts the suction of the scavenging into the cylinder according to the opening and closing timing of the scavenging passage opening. The scavenging passage opening is formed in an arc shape having substantially the same width in the rotation direction of the crank web, and further, the opening end face is recessed from the opening in the counter-rotation direction. A disc valve device for a stratified scavenging two-cycle engine, characterized by having a large opening area as a whole. The stratified scavenging two-cycle engine according to claim 1 or 2, wherein the scavenging branch passage and the air branch passage formed on both sides of the cylinder are formed by being surrounded by substantially parallel passage walls in the same direction.

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