US3752129A - Two-cycle internal combustion engines - Google Patents

Two-cycle internal combustion engines Download PDF

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Publication number
US3752129A
US3752129A US00232569A US3752129DA US3752129A US 3752129 A US3752129 A US 3752129A US 00232569 A US00232569 A US 00232569A US 3752129D A US3752129D A US 3752129DA US 3752129 A US3752129 A US 3752129A
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United States
Prior art keywords
cylinder
port
scavenging
mixture
charging
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Expired - Lifetime
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US00232569A
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English (en)
Inventor
T Kobayashi
H Inaga
K Nakagawa
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Kioritz Corp
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Kyoritsu Noki Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B25/00—Engines characterised by using fresh charge for scavenging cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2700/00—Measures relating to the combustion process without indication of the kind of fuel or with more than one fuel
    • F02B2700/03—Two stroke engines
    • F02B2700/037—Scavenging or charging channels or openings

Definitions

  • This invention relates to two-cycle internal combustion engines of the type in which a mixture is sucked into a crank case through a reed valve, and more particularly to improvements in the scavenging system of such engines.
  • the primary object of the invention is to improve the scavenging and charging effects of twocycle internal combustion engines and thereby to increase the engine output.
  • a scavenging stroke is an operational phase of a cylinder in which the combustion gas remaining in the combustion chamber of the cylinder is scavenged and replaced by a fresh mixture, and in order to exhaust the residual combustion gas effectively, it has been a conventional practice to utilize the pulsation in the exhaust system including the exhaust pipe, the muffler, etc., to create scavenging flows within the combustion chamber by forced charging means, to utilize a jet of mixture injected from an additional charging port, or to use all of the above-mentioned methods in combination.
  • the present invention contemplates the provision of a two-cycle internal combustion engine which is free of such disadvantages.
  • a main scavenging port (passage), an auxiliary scavenging port (passage) and a charging port (passage) are provided in the wall of a cylinder for the specific purposes to be attained thereby.
  • the charging port is located at the diametrically opposite position to the exhaust port.
  • At least one main scavenging port and at least one auxiliary scavenging port are provided symmetrically on each side of a vertical plane which contains a straight line interconnecting the centers of said charging port and exhaust port, and extends along the axis of the cylinder, and the directions of said main and auxiliary scavenging ports are so established that the jets of mixture injected from said ports may intersect each other in a predetermined region in the combustion chamber of the cylinder, which is located at a position more than the half of the distance between the center of the cylinder and the charging port distant from said center of the cylinder toward said charging port.
  • the direction of the charging port is so established that the jet of mixture injected from said port may be directed toward a space slightly above the region of intersection of the aforesaid scavenging flows and provide a uni-flow along the upper side of said scavenging flows, without directly crossing said scavenging flows.
  • the positional relation of the auxiliary and main scavenging ports circumferentially of the cylinder wall is such that said auxiliary scavenging port is closer to the charging port than said main scavenging port.
  • reed valve means is disposed in that side of the crank case where the tangential component of rotational force of the crankshaft is directed toward the cylinder skirt and at a position adjacent said cylinder skirt, and the other open ends of the charging and auxiliary passages are located circumferentially of said cylinder skirt and at positions in the proximity of said reed valve means.
  • the jets of mixture injected from the main and auxiliary scavenging ports intersect each other in the predetermined region located in the deep portion of the combustion chamber and furthermore the jet of mixture injected from the charging port is directed to a portion slightly above said region of intersection and flows along the upper side of said main and auxiliary scavenging flows, the resultant flow sufficiently reaches the deep of the combustion chamber while swirling, so that the combustion gas remaining in the deep portion as well as other portion can be substantially completely scavenged. Therefore, the scavenging and charging effects of the two-cycle internal combustion engine can be improved.
  • the transverse sectional areas of the auxiliary scavenging port and charging port are made smaller than that of the main scavenging port so as to increase the velocity of mixture injected therefrom, the scattering of the scavenging mixture can be prevented and a desired scavenging flow can be secured. Particularly, the scavenging during high speed operation of the engine can be achieved positively and effectively.
  • FIG. 1 is a vertical sectional view of a two-cycle internal combustion engine according to the present invention
  • FIG. 2 is a plan view of the cylinder mounting face of the crank case of the internal combustion engine shown in FIG. 1 exemplified as a two cylinders type;
  • FIG. 3 is a vertical sectional view of the cylinder of the two-cycle internal combustion engine
  • FIG. 4 is a vertical sectional view of the reed valve means
  • FIG. 5 is a transverse sectional view of the cylinder of a single cylinder, two-cycle internal combustion engine according to the invention.
  • FIG. 6 is a transverse sectional view of a multicylinder, two-cycle internal combustion engine according to the invention.
  • FIG. 7 is a view similar to FIG. 6 but additionally showing the arrangement of the crank shaft within the crank case.
  • FIG. 1 there is shown a two-cycle internal combustion engine according to the present invention, in which numeral 1 designates a cylinder, and 2 and 3 designate upper and lower parts of a crank case respectively.
  • the upper part 2 of the crank case is formed with reed valve chambers 24 for mounting reed valve means 9 therein, and a mixture from a carbureter (not shown) is sucked into the crank case through said reed valve means.
  • Numeral 8 designates a crank shaft which rotates in the direction of the arrow A or in a counterclockwise direction. Therefore, the reed valve means 9 are provided within the crank case on the side where the tangential component of rotational force of the crank shaft 8 is directed toward a cylinder skirt 19, and at locations adjacent said cylinder skirt respectively.
  • crank case As seen in FIG. 2, in the cylinder mounting face 20 of the crank case is formed with cutouts 16" and 17" for communication with a main scavenging passage, an auxiliary scavenging passage and a charging passage respectively, which are formed in the wall of the cylinder 1.
  • the crank case shown in FIG. 2 is of a two-cylinder, two-cycle internal combustion engine, and vertical planes X-X of symmetry of the port arrangements for the respective cylinders are inclined symmetrically with respect to a vertical plane S--S through the center of the crank case, for the purpose of reducing the distance between the axes of the two cylinders arranged side by side and thereby reducing the lateral width of the internal combustion engine (crank case).
  • Numeral 26 designates cavities for mounting the cylinders 1 therein and 24 designates the profiles of the reed valve chamber formed in the crank case 2 for mounting the reed valve means therein. From the position of the chamber 24 in the circumferential direction of the cylinder, it will be understood that each reed valve means is arranged adjacent the auxiliary scavenging passage and charging passage.
  • the reed valve means 9 proper is shown in FIG. 4.
  • the reed valve means includes a box body 18 having an isosceles-triangular cross section and projecting into the crank case, and plate valve elements 10 coven ing a plurality of openings formed in the chevronshaped wall of said box body.
  • the plate valve elements 10 are biased against the chevron-shaped surface of the box body by means of limiting plates 11 and secured at one end to the box body 18 by means of set screws 21, respectively.
  • the limiting plates 11 limit the amount of deformation of the plate valve elements 10 or the degree of opening of the valve means, and also prevent irregular operations of said plate valve elements caused by vibrations, etc.
  • the plate valve elements 10 are opened toward downstream (the arrow B in FIG. 4 indicates the flow direction of mixture), but are tightly seated on the surface of the box body 18 when the pressure on the downstream side or interior of the crank case is relatively high, thereby interrupting the supply of mixture. Thus, the back flow of the mixture can be completely prevented.
  • FIGS. 5 and 45 are transverse sectional views of the cylinder of the two-cycle internal combustion engine of the invention, taken along the line Z-Z of FIG. I, respectively.
  • FIG. 5 is of the engine having a single cylinder
  • FIG. 6 is of the engine having a multiplicity of cylinders.
  • FIG. 7 is a transverse sectional view similar to FIG. 6 but with parts within the crank case, such as the crank shaft, added thereto as seen through the cylinder, to facilitate understanding of the positional relation between the crank shaft 8, and the auxiliary scavenging passages 16' and the charging passages 17' and further the main scavenging passages 15'.
  • the cylinder 1 is formed with an exhaust port 14 and a charging port 17 at the diametrically opposite position to said exhaust port. It is also provided with main scavenging ports 15 and auxiliary scavenging ports 16 on both sides of the vertical plane X-X which includes the straight line connecting the centers of the exhaust port 14 and charging port 17 and extending along the axis of the cylinder, and in symmetrical relation with respect to said vertical line.
  • the positional relation in the circumferential direction of the cylinder of the auxiliary scavenging ports 16 and main scavenging ports 15 is such that said auxiliary scavenging ports are located closer to the charging port 17 than said main scavenging ports.
  • the directions of these main scavenging ports 15 and auxiliary scavenging ports 16 are so established that the mixture may be injected from these ports upwardly at an angle of about 15 to the transverse sectional plane of the cylinder 1 and further the jets of mixture from all of these ports may intersect each other in the region indicated by character 0 in FIG. 5.
  • the region 0 when viewed from the upper side of the cylinder is located on the diameter of the cylinder contained in the aforesaid vertical plane X-X and at a position more than the half of the distance between the center of the cylinder and the charging port distant from said cylinder center toward said charging port. According to the experiment conducted by the present inventor, the best result was obtained when the region 0 was set in an area defined by l/D 0.2 wherein D is the diameter of the cylinder and l is the distance between said region and the charging port.
  • the positional relation of these ports is such that the jet of mixture injected from the main scavenging port on one side of the vertical plane X-X and the jet of mixture injected from the auxiliary scavenging port on the other side of said vertical plane are opposed by each other and collide against each other on a substantially straight line.
  • the internal angle or with respect to the center of cylinder defined by the jets of mixture injected from the main scavenging ports on both sides of the vertical plane X-X and crossing in the region 0 was set at about l25 and the external angle B with respect to the center of cylinder, defined by the jets of mixture injected from the auxiliary scavenging ports on both sides of said vertical plane and crossing in the region 0, was set at about 147".
  • the main and auxiliary scavenging ports are arranged as described above, namely the angles a and [3 will become 125 and l47 respectively and the jet of mixture injected from the main scavenging port on one side of. the vertical plane X-X and the jet mixture injectedfrom the auxiliary scavenging port on the other side of said vertical plane will be substantially opposed by each other.
  • the direction of the charging port is so established that the jet mixture injected from said charging port may be directed toward a space slightly above the region 0 and flow along the upper side of the aforesaid scavenging flows in the form of an independent flow without crossing said scavenging flows.
  • a highly satisfactory result was obtained when the main and auxiliary scavenging flows were directed upwardly at an angle of with respect to the transverse sectional plane of the cylinder and the jet of mixture from the charging port was directed upwardly at an angle of about 60 with respect to said transverse sectional plane.
  • the jets of mixture injected from the main scavenging ports of a relatively large capacity and the jets of mixture injected from the auxiliary scavenging ports are cross each other in the region 0, so that the combustion gas in the combustion chamber is urged toward the exhaust port and readily exhausted from said exhaust port.
  • the mixture is injected from the charging port toward the portion slightly above the region 0 and flows as a uni-flow along the upper side of the main and auxiliary scavenging flows and said uni-flow of mixture is urged further upwardly due to the impact pressure of said main and auxiliary scavenging flows and the relatively large volumes (masses) of the same-Therefore, there can be obtained such advantage that the ignition plug and other portions of the cylinder head, which are high in temperature, are cooled directly by the fresh mixture which is relatively low in temperature, brought into contact therewith. Thereafter, this fresh mixture swirls in the upper portion of the combustion chamber, also urging the combustion gas, remaining in said portion, toward the exhausted therefrom, thus ensuring complete discharge of the combustion gas.
  • the scavenging of the cylinders can be achieved satisfactorily, and thereby the exhaust and charging efficiencies can be enhanced and the engine output can be increased, even if the cylinders or combustion chambers are of a shape which is quite undesirable for the smooth flow of scavenging and intake mixture and even when the period of the scavenging stroke is very short during rotation of the engine at a high speed.
  • a mixture suction system comprising the reed valve means which operates automatically in response to the pressure of mixture, and, therefore, back-flow of the mixture can be completely prevented.
  • the reed valve means is disposed in that side of the crank case where the tangential component of rotational force of the crank shaft is directed toward the cylinder skirt, and the openings of the auxiliary scavenging passages and charging passage are lo- "cated peripherally of said cylinder skirt and adjacent said reed valve means, the mixture within the crank case is urged toward and directed into said openings under the influence of said tangential component of rotational force, and thus an additional charging effect can be obtained.
  • the two-cycle internal combustion engine is characterized by the facts that a charging port is provided in the wall of the cylinder at the diametrically opposite position to an exhaust port; that at least one main scavenging port and at least one auxiliary scavenging port are provided on each side of a vertical plane including the straight line connecting the centers of said exhaust port and charging port and extending along the axis, of the cylinder in such a way that said auxiliary scavenging port is closer to said charging port than said main scavenging port; that the directions of said main scavenging port and auxiliary scavenging port are so established that the mixture may be injected from these ports upwardly at an angle of about to the transverse sectional plane of the cylinder and further the jets of mixture from all of these ports may intersect each other in a predetermined region which is located on the diameter of the cylinder contained in said vertical plane and at a position distant from the center of the cylinder toward said charging port; that the direction of said charging port
  • scavenging passage and further the opening of the main scavenging passage are located circumferentially of said cylinder skirt and at positions adjacent said reed valve means, whereby the mixture sucked into the crank case is imparted with a kinetic energy by which said mixture is urged toward and led into said openings, and thus the charging of the mixture into the cylinder is promoted.
  • a two-cycle internal combustion engine with crank case containing a crank shaft in a cylinder comprising a reed valve means for introducing the combustible mixture therethrough disposed in that side of the crank case where the tangential component of rotational force of the crank shaft is directed toward a skirt of the cylinder; a charging port provided in the wall of the cylinder in a diametrically opposite position to an exhaust port; at least one main scavenging port and at least one auxiliary scavenging port provided on each side of a vertical plane containing the straight line connecting the centers of said exhaust port and said charging port and extending along the axis of the cylinder, the relative position of said'main scavenging port and said auxiliary scavenging port being such that said auxiliary scavenging port is closer to said charging port than said main scavenging'port; the directions of said main and auxiliary scavenging ports so established that the mixture may be injected from said ports upwardly at an angle of approximately l5 to the

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
US00232569A 1971-12-17 1972-03-07 Two-cycle internal combustion engines Expired - Lifetime US3752129A (en)

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JP46102483A JPS4867616A (enrdf_load_stackoverflow) 1971-12-17 1971-12-17

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092958A (en) * 1975-09-04 1978-06-06 Brunswick Corporation Internal combustion engine
US4143626A (en) * 1977-10-04 1979-03-13 Performance Industries, Inc. Injector porting for two cycle internal combustion engine
US4161163A (en) * 1972-08-22 1979-07-17 Performance Industries, Inc. Two cycle internal combustion engine
US4180042A (en) * 1978-05-08 1979-12-25 Lloyd David J Fuel-air mixture regulator for internal combustion engines
US4194470A (en) * 1978-03-13 1980-03-25 Magner Richard W Two-cycle internal combustion engine having boost port
US5372105A (en) * 1992-10-08 1994-12-13 Kioritz Corporation Combustion chamber for two-cycle internal combustion engine
US5471960A (en) * 1992-10-08 1995-12-05 Kioritz Corporation Cylinder for two-cycle internal combustion engine
US20040244739A1 (en) * 2002-10-04 2004-12-09 Sheldon John D. Two-stroke engine transfer ports
US20090013982A1 (en) * 2007-06-28 2009-01-15 Tsuneyoshi Yuasa Two-cycle engine cylinder and method for manufacturing the same
CN101839167A (zh) * 2009-03-17 2010-09-22 日立工机株式会社 二冲程发动机和装备有二冲程发动机的动力工具
US20110017183A1 (en) * 2009-07-24 2011-01-27 Yamabiko Corporation Two-stroke internal combustion engine

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61294121A (ja) * 1985-06-21 1986-12-24 Yamaha Motor Co Ltd ２行程エンジンの燃焼室
JP5263709B2 (ja) * 2008-06-13 2013-08-14 日立工機株式会社 ２サイクルエンジン

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4730643U (enrdf_load_stackoverflow) * 1971-04-24 1972-12-07

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161163A (en) * 1972-08-22 1979-07-17 Performance Industries, Inc. Two cycle internal combustion engine
US4092958A (en) * 1975-09-04 1978-06-06 Brunswick Corporation Internal combustion engine
US4143626A (en) * 1977-10-04 1979-03-13 Performance Industries, Inc. Injector porting for two cycle internal combustion engine
US4194470A (en) * 1978-03-13 1980-03-25 Magner Richard W Two-cycle internal combustion engine having boost port
US4180042A (en) * 1978-05-08 1979-12-25 Lloyd David J Fuel-air mixture regulator for internal combustion engines
US5372105A (en) * 1992-10-08 1994-12-13 Kioritz Corporation Combustion chamber for two-cycle internal combustion engine
US5471960A (en) * 1992-10-08 1995-12-05 Kioritz Corporation Cylinder for two-cycle internal combustion engine
US7100550B2 (en) 2002-10-04 2006-09-05 Homelite Technologies, Ltd. Two-stroke engine transfer ports
US20040244739A1 (en) * 2002-10-04 2004-12-09 Sheldon John D. Two-stroke engine transfer ports
US20090013982A1 (en) * 2007-06-28 2009-01-15 Tsuneyoshi Yuasa Two-cycle engine cylinder and method for manufacturing the same
US8146546B2 (en) * 2007-06-28 2012-04-03 Kawasaki Jukogyo Kabushiki Kaisha Two-cycle engine cylinder and method for manufacturing the same
CN101839167A (zh) * 2009-03-17 2010-09-22 日立工机株式会社 二冲程发动机和装备有二冲程发动机的动力工具
US20100236082A1 (en) * 2009-03-17 2010-09-23 Hitachi Koki Co., Ltd. Two-stroke engine and motorized implement equipped with the two-stroke engine
US8550043B2 (en) 2009-03-17 2013-10-08 Hitachi Koki Co., Ltd. Two-stroke engine and motorized implement equipped with the two-stroke engine
CN101839167B (zh) * 2009-03-17 2015-08-26 日立工机株式会社 二冲程发动机和装备有二冲程发动机的动力工具
US20110017183A1 (en) * 2009-07-24 2011-01-27 Yamabiko Corporation Two-stroke internal combustion engine
EP2278137A3 (en) * 2009-07-24 2011-10-19 Yamabiko Corporation Two-stroke internal combustion engine
US8353262B2 (en) 2009-07-24 2013-01-15 Yamabiko Corporation Two-stroke internal combustion engine

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